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Lung adenocarcinoma is one of the most fatal types of cancer worldwide, with non-small cell lung cancer being the most common subtype. Therefore, there is need for improved treatment approaches. Tumor growth results from the proliferation of a very small number of tumor stem cells, giving rise to the theory of cancer stem cells (CSCs). Lung CSCs are associated with lung cancer development, and although chemotherapy drugs can inhibit the proliferation of lung cancer cells, they have difficulty acting on lung CSCs. Even if the tumor appears to have disappeared after chemotherapy, the presence of a small number of residual tumor stem cells can lead to cancer recurrence and metastasis. Hence, targeting and eliminating lung CSCs is of significant therapeutic importance. In this study, we cultured A549 cells in sphere-forming conditions using B27, EGF, and bFGF, isolated peripheral blood mononuclear cells (PBMCs), and induced and characterized dendritic cells (DCs). We also isolated and expanded T lymphocytes. DC vaccines were prepared using A549 stem cell lysate or A549 cell lysate for sensitization and compared with non-sensitized DC vaccines. The content of IFN-γ in the supernatant of cultures with vaccines and T cells was measured by ELISA. The cytotoxic effects of the vaccines on A549 cells and stem cells were assessed using the Cytotox96 assay, and the impact of the vaccines on A549 cell migration and apoptosis was evaluated using Transwell assays and flow cytometry. DC vaccines sensitized with human lung CSC lysates induced significant in vitro cytotoxic effects on A549 lung cancer cells and CSCs by T lymphocytes, while not producing immune cytotoxic effects on human airway epithelial cells. Moreover, the immune-killing effect induced by DC vaccines sensitized with lung CSC lysates was superior to that of DC vaccines sensitized with lung cancer cells. [ABSTRACT FROM AUTHOR]

Background: Pituitary adenomas (PAs) are the second most common intracranial tumor. While current diagnostic practices rely primarily on histological testing, they often fail to capture the molecular complexities of pituitary adenomas, underscoring the need for a molecular-based classification to refine therapeutic strategies and prognostic assessments. This study aims to provide a molecularly unbiased classification of pituitary adenomas and explore their unique gene expression patterns and clinical features. Methods: We performed unsupervised hierarchical clustering of the gene expression profiles of 117 PA samples to identify three distinct molecular subtypes. Subsequently, we analyzed the compiled transcriptomic profiles of each individual subtype for pathway enrichment. We also validated the new classification with a validation set containing 158 PAs and 24 pituitary adenoma stem cells (PASCs). Results: Consensus clustering of transcriptomic data from 117 pituitary adenoma (PA) samples identified three distinct molecular subtypes, each showing unique gene expression patterns and associated biological processes: Group I is enriched in signaling pathways, such as the cAMP signaling pathway and the calcium signaling pathway. Group II is primarily related to metabolic processes, including nitrogen metabolism and arginine biosynthesis in cancer. Group III predominantly shows enrichment in immune responses and potential malignant transformation of the disease, especially through cancer-related pathways such as the JAK–STAT signaling pathway and the PI3K–Akt signaling pathway. The immune profiling revealed distinct patterns for each subtype: Group I had higher dendritic cells and fewer CD8+ T cells, Group II had more monocytes and macrophages, and Group III had elevated levels of T cells. Additionally, there were differences in clinical characteristics and prognosis among the subtypes, with Group III having a worse prognosis, despite the smaller tumor size compared to other groups. Notably, differences in PASCs correlated with the molecular subtypes, with Group III stem cells being enriched in tumorigenesis pathways, PI3K–Akt signaling pathway and Ras signaling pathway. Conclusion: Our study introduces a novel molecular classification for pituitary adenomas, independent of traditional histological methods. Each subtype features distinct genetic, molecular, and immunological profiles. We have isolated pituitary adenoma stem-like cells (PASCs), pairing them with tumor tissues for detailed transcriptomic analysis. These PASCs exhibit diverse molecular traits consistent with the new classification. [ABSTRACT FROM AUTHOR]

Acetyl CoA acetyltransferase 1 (ACAT1), a mitochondrial enzyme, is mainly involved in the formation and decomposition of ketones, isoleucine, and fatty acids. Previous clinical studies showed that mutations in the ACAT1 gene lead to ketoacidosis, Notably the role of ACAT1 in human cancer' pathogenesis varies depending on cancer type, and its specific role in gastric cancer remains largely unknown. In the current study, we found that the expression of ACAT1 in primary late-stage gastric cancer tumor tissues was significantly lower than in early-stage tumors. This observation was further confirmed in high-grade gastric cancer cell line MKN45. The expression of CD44 and OCT4 was decreased, while CD24 expression was increased by overexpressing ACAT1 in MKN45 gastric cancer cells. Moreover, the ability of gastric cancer cells to form colonies on soft agar was also reduced by ACAT1 overexpression. Likewise, overexpression of ACAT1 inhibited epithelial mesenchymal transition (EMT) in gastric cancer cells evidenced by increased expression of the epithelial marker E-Cadherin, decreased expression of mesenchymal marker vimentin, and decreased expression levels of SNAI 1/3. In addition, ACAT1 overexpression inhibited cell migration and invasion, improved the response to 5-Fluorouracil (5-FU) and etoposide. In contrast, inhibition of ACAT1 activity promoted the proliferation of gastric cancer cells. The xenotransplantation results in nude mice showed that overexpression of ACAT1 in gastric cancer cells inhibited tumor growth in vivo. In addition, the low expression of ACAT1 in gastric cancer was further validated by searching public databases and conducting bioinformatic analyses. Mechanistically, bioinformatic analysis found that the inhibitory effect of ACAT1 in gastric cancer may be related to the Adipocytokine Signaling Pathway, Ppar Signaling Pathway, Propanoate Metabolism and P53 Signaling Pathway. Correlation analysis indicated ACAT1 mRNA expression was correlated with immune infiltrates. Collectively, our data show that ACAT1 induces pronounced inhibitory effects on gastric cancer initiation and development, which may impact future strategies to treat this aggressive cancer. [ABSTRACT FROM AUTHOR]

Cancer stem cells (CSCs) are a small group of cells found in tumors that have same self-renewing properties as nor‑ mal stem cells. In recent years, with continuous development of science and technology in various aspects, people's research on tumor diseases has been deepened. CSCs has been defined as a key factor in promoting tumor development, especially participating in pro‑ moting tumor recurrence, metastasis, chemotherapy resistance, etc. Currently, CD133 has become one of popular CSCs markers, and can be highly expressed in a variety of CSCs. CD133 is closely related to diagnosis of cancer diseases, and plays an important role in dignosis and drug targeting for gastric cancer, lung cancer, brain tumor, liver cancer, ovarian cancer and colorectal cancer. This article reviews structure, function, immune mechanism escape of CD133, signal pathway of CD133 in tumorigenesis, and correlation of CD133 with various tumors as well. [ABSTRACT FROM AUTHOR]

Abstract Background Pituitary adenomas (PAs) are the second most common intracranial tumor. While current diagnostic practices rely primarily on histological testing, they often fail to capture the molecular complexities of pituitary adenomas, underscoring the need for a molecular-based classification to refine therapeutic strategies and prognostic assessments. This study aims to provide a molecularly unbiased classification of pituitary adenomas and explore their unique gene expression patterns and clinical features. Methods We performed unsupervised hierarchical clustering of the gene expression profiles of 117 PA samples to identify three distinct molecular subtypes. Subsequently, we analyzed the compiled transcriptomic profiles of each individual subtype for pathway enrichment. We also validated the new classification with a validation set containing 158 PAs and 24 pituitary adenoma stem cells (PASCs). Results Consensus clustering of transcriptomic data from 117 pituitary adenoma (PA) samples identified three distinct molecular subtypes, each showing unique gene expression patterns and associated biological processes: Group I is enriched in signaling pathways, such as the cAMP signaling pathway and the calcium signaling pathway. Group II is primarily related to metabolic processes, including nitrogen metabolism and arginine biosynthesis in cancer. Group III predominantly shows enrichment in immune responses and potential malignant transformation of the disease, especially through cancer-related pathways such as the JAK–STAT signaling pathway and the PI3K–Akt signaling pathway. The immune profiling revealed distinct patterns for each subtype: Group I had higher dendritic cells and fewer CD8+ T cells, Group II had more monocytes and macrophages, and Group III had elevated levels of T cells. Additionally, there were differences in clinical characteristics and prognosis among the subtypes, with Group III having a worse prognosis, despite the smaller tumor size compared to other groups. Notably, differences in PASCs correlated with the molecular subtypes, with Group III stem cells being enriched in tumorigenesis pathways, PI3K–Akt signaling pathway and Ras signaling pathway. Conclusion Our study introduces a novel molecular classification for pituitary adenomas, independent of traditional histological methods. Each subtype features distinct genetic, molecular, and immunological profiles. We have isolated pituitary adenoma stem-like cells (PASCs), pairing them with tumor tissues for detailed transcriptomic analysis. These PASCs exhibit diverse molecular traits consistent with the new classification.

As a key factor in tumorigenesis, progression, recurrence and metastasis, the biological properties, metabolic adaptations and immune escape mechanisms of CSCs are the focus of current oncological research. CSCs possess self-renewal, multidirectional differentiation and tumorigenicity, and their mechanisms of action can be elucidated by the clonal evolution, hierarchical model and the dynamic CSCs model, of which the dynamic model is widely recognized due to its better explanation of the function and origin of CSCs. The origin hypothesis of CSCs involves cell-cell fusion, horizontal gene transfer, genomic instability and microenvironmental regulation, which together shape the diversity of CSCs. In terms of classification, CSCs include primary CSCs (pri-CSCs), precancerous stem cells (pre-CSCs), migratory CSCs (mig-CSCs), and chemo-radiotherapy-resistant CSCs (cr-CSCs and rr-CSCs), with each type playing a specific role in tumor progression. Surface markers of CSCs, such as CD24, CD34, CD44, CD90, CD133, CD166, EpCAM, and LGR5, offer the possibility of identifying, isolating, and targeting CSCs, but the instability and heterogeneity of their expression increase the difficulty of treatment. CSCs have adapted to their survival needs through metabolic reprogramming, showing the ability to flexibly switch between glycolysis and oxidative phosphorylation (OXPHOS), as well as adjustments to amino acid and lipid metabolism. The Warburg effect typifies their metabolic profiles, and altered glutamine and fatty acid metabolism further contributes to the rapid proliferation and survival of CSCs. CSCs are able to maintain their stemness by regulating the metabolic networks to maintain their stemness characteristics, enhance antioxidant defences, and adapt to therapeutic stress. Immune escape is another strategy for CSCs to maintain their survival, and CSCs can effectively evade immune surveillance through mechanisms such as upregulating PD-L1 expression and promoting the formation of an immunosuppressive microenvironment. Together, these properties reveal the multidimensional complexity of CSCs, underscoring the importance of a deeper understanding of the biology of CSCs for the development of more effective tumor therapeutic strategies. In the future, therapies targeting CSCs will focus on precise identification of surface markers, intervention of metabolic pathways, and overcoming immune escape, with the aim of improving the relevance and efficacy of cancer treatments, and ultimately improving patient prognosis. [ABSTRACT FROM AUTHOR]

Objective: In the era of image-guided adaptive radiotherapy, definition of the clinical target volume (CTV) is a challenge in various solid tumors, including esophageal cancer (EC). Many tumor microenvironmental factors, e.g., tumor cell proliferation or cancer stem cells, are hypothesized to be involved in microscopic tumor extension (MTE). Therefore, this study assessed the expression of FAK, ILK, CD44, HIF-1α, and Ki67 in EC patients after neoadjuvant radiochemotherapy followed by tumor resection (NRCHT+R) and correlated these markers with the MTE. Methods: Formalin-fixed paraffin-embedded tumor resection specimens of ten EC patients were analyzed using multiplex immunofluorescence staining. Since gold fiducial markers had been endoscopically implanted at the proximal and distal tumor borders prior to NRCHT+R, correlation of the markers with the MTE was feasible. Results: In tumor resection specimens of EC patients, the overall percentages of FAK+, CD44+, HIF-1α+, and Ki67+ cells were higher in tumor nests than in the tumor stroma, with the outcome for Ki67+ cells reaching statistical significance (p < 0.001). Conversely, expression of ILK+ cells was higher in tumor stroma, albeit not statistically significantly. In three patients, MTE beyond the fiducial markers was found, reaching up to 31 mm. Conclusion: Our findings indicate that the overall expression of FAK, HIF-1α, Ki67, and CD44 was higher in tumor nests, whereas that of ILK was higher in tumor stroma. Differences in the TME between patients with residual tumor cells in the original CTV compared to those without were not found. Thus, there is insufficient evidence that the TME influences the required CTV margin on an individual patient basis. Trial registration number and date: BO-EK-148042017 and BO-EK-177042022 on 20.06.2022, DRKS00011886, https://drks.de/search/de/trial/DRKS00011886. [ABSTRACT FROM AUTHOR]

Objective To explore the effects and mechanism of bone morphogenetic protein 9(BMP9) on the stem‐ ness, proliferation and invasion of cancer stem cells (CSCs) in hepatocellular carcinoma (HCC). Methods Normal liv‐ er cells, liver carcinoma cells, and liver carcinoma tumor stem cells in the logarithmic growth phase were selected. RT-qP‐ CR was used to detect BMP9 mRNA expression. Western blotting was used to detect BMP9 protein expression. HepG2- CSCs were transfected with lentiviral interference vectors to knock down BMP9 expression, which were then divided into HepG2-CSCs group and HepG2-CSCs-BMP9 knockdown group. After adding MAPK/ERK signal agonists (DIPQUO), cells were divided into three groups, HepG2-CSCs group, HepG2-CSCs knockdown group, and HepG2-CSCs knockdown+ DIPQUO group. RT-qPCR was used to detect the expression levels of stemness-related molecules CD44, SOX2, and OCT4 in HepG2-CSCs. CCK-8 assay was used to detect cell proliferation ability. Transwell assay was used to detect cell in‐ vasion ability. Western blotting was used to detect the expression of key proteins in the MAPK/ERK pathway. Results Compared with normal liver cells, BMP9 expression was up-regulated in liver carcinoma cells and HepG2-CSCs (P< 0. 05). The BMP9 mRNA and protein expression levels in HepG2-CSCs were higher than those in HepG2 cells (both P< 0. 05). After BMP9 knockdown, the mRNA expression levels of stem cell-related markers CD44, SOX2, and OCT4 in HepG2 CSCs in the HepG2-CSCs-BMP9 knockdown group were lower than those in the HepG2-CSCs group (all P<0. 05). Compared with the HepG2-CSCs group, BMP9 knockdown inhibited the cell proliferation ability of HepG2-CSCs in the HepG2-CSCs-BMP9 knockdown group at 48, 72, and 96 h (all P<0. 05), and inhibited the migration and invasion abili‐ ties of HepG2-CSCs cells (all P<0. 05). Compared with the HepG2-CSCs group, after BMP9 knockdown, the expression levels of p-ERK1/2 and p-MEK1/2 proteins in the HepG2-CSCs-BMP9 knockdown group significantly decreased (all P< 0. 05). After adding DIPQUO, the expression levels of stem cell-related markers CD44, SOX2, and OCT4 mRNA increased in the HepG2-CSCs knockdown+DIPQUO group (all P<0. 05), and the proliferation and invasion abilities of HepG2-CSCs were enhanced (all P<0. 05). Conclusion Knockdown of BMP9 can inhibit the dry maintenance and pro‐ liferation and invasion functions of HepG2 CSCs, and the mechanism may be related to the inhibition of the MAPK/ERK pathway. [ABSTRACT FROM AUTHOR]

Lung cancer is the leading cause of cancer-related death worldwide. Its high mortality is partly due to chronic inflammation that accompanies the disease and stimulates cancer progression. In this review, we analyzed recent studies and highlighted the role of the epithelial–mesenchymal transition (EMT) as a link between inflammation and lung cancer. In the inflammatory tumor microenvironment (iTME), fibroblasts, macrophages, granulocytes, and lymphocytes produce inflammatory mediators, some of which can induce EMT. This leads to increased invasiveness of tumor cells and self-renewal of cancer stem cells (CSCs), which are associated with metastasis and tumor recurrence, respectively. Based on published data, we propose that inflammation-induced EMT may be a potential therapeutic target for the treatment of lung cancer. This prospect is partially realized in the development of EMT inhibitors based on pentacyclic triterpenoids (PTs), described in the second part of our study. PTs reduce the metastatic potential and stemness of tumor cells, making PTs promising candidates for lung cancer therapy. We emphasize that the high diversity of molecular mechanisms underlying inflammation-induced EMT far exceeds those that have been implicated in drug development. Therefore, analysis of information on the relationship between the iTME and EMT is of great interest and may provide ideas for novel treatment approaches for lung cancer. [ABSTRACT FROM AUTHOR]

Background: Gonadotrophic pituitary adenoma is a major subtype of pituitary adenoma in the sellar region, but it is rarely involved in the hypersecretion of hormones into blood; thus, it is commonly regarded as "non-functioning." Its tumorigenic mechanisms remain unknown. The aim of this study was to identify human gonadotrophic pituitary adenoma stem cells (hPASCs) and explore the underlying gene expression profiles. In addition, the potential candidate genes involved in the invasive properties of pituitary adenoma were examined. Methods: The hPASCs from 14 human gonadotrophic pituitary adenoma clinical samples were cultured and verified via immunohistochemistry. Genetic profiling of hPASCs and the matched tumor cells was performed through RNA-sequencing and subjected to enrichment analysis. By aligning the results with public databases, the candidate genes were screened and examined in invasive and non-invasive gonadotrophic pituitary adenomas using Real-time polymerase chain reaction. Results: The hPASCs were successfully isolated and cultured from gonadotrophic pituitary adenoma in vitro, which were identified as positive for generic stem cell markers (Sox2, Oct4, Nestin and CD133) via immunohistochemical staining. The hPASCs could differentiate into the tumor cells expressing follicle-stimulating hormone in the presence of fetal bovine serum in the culture medium. Through RNA-sequencing, 1352 differentially expressed genes were screened and identified significantly enriched in various gene ontologies and important pathways. The expression levels of ANXA2, PMAIP1, SPRY2, C2CD4A, APOD, FGF14 and FKBP10 were significantly upregulated while FNDC5 and MAP3K4 were downregulated in the invasive gonadotrophic pituitary adenomas compared to the non-invasive ones. Conclusion: Genetic profiling of hPASCs may explain the tumorigenesis and invasiveness of gonadotrophic pituitary adenoma. ANXA2 may serve as a potential therapeutic target for the treatment of gonadotrophic pituitary adenoma. [ABSTRACT FROM AUTHOR]

Background: Neurofibroma type I (NF1) often presents with multiple clinical phenotypes due to mutations of NF1 gene. The aim of this study was to determine the phenotypic and therapeutic relevance of tumor microenvironment in NF1 patients. Methods: Tumor stem cells (TSCs) from NF1 were isolated and cultured using fluorescence activated cell sorting (FACS) and colony formation experiments. Then, flow cytometry was used to detect the surface markers, osteogenic and adipogenic differentiation were performed as well. Its tumorigenesis ability was confirmed by subcutaneous tumorigenesis in nude mice. Immunohistochemical staining was performed on neurofibroma tissues from the head and trunk with different phenotypes. The expression of BDNF in neurofibroma tissues was detected by Elisa and immunohistochemical staining. Western Blotting was used to detect the expression of p38 MAPK pathway in TSCs. The effect of BDNF neutralizing antibody on the tumorigenesis of TSCs was observed. Results: Herein, we advocate that NF1 contain a new subgroup of mesenchymal-like neurofibroma stem cells (MNSCs). Such colony-forming MNSCs preserved self-renewal, multiple differentiation and tumorigenic capabilities. More interestingly, the MNSCs isolated from neurofibroma tissues of the same patient with different phenotypes presented site-specific capabilities. Moreover, different levels of brain-derived neurotrophic factor (BDNF) in neurofibroma tissues can impact the MNSCs by activating the TrkB/p38 MAPK pathway. Systemic administration of BDNF neutralizing antibodies inhibited MNSCs’ characteristics. Conclusions: We demonstrated that BDNF can modulate MNSCs and thereby controlling different tumor phenotypes between the head and trunk regions. Application of BDNF neutralizing antibodies may inhibit p38 MAPK pathway, therefore providing a promising strategy for managing NF1.

In our efforts to identify molecules that selectively reduce the expression of BMI1, a stem cell gene, we discovered and characterized the first‐in‐class series of small molecules that modulate the expression of BMI1 protein in cancer cells. Structure–activity and structure–property relationships associated with this series were investigated through medicinal chemistry efforts. These studies revealed important structural features required for achieving anti‐tumor activity and acceptable pharmacokinetic properties within this series. The 4‐CF3−Ph at the left‐side of the molecule, a proper placement of the N‐atom on the six‐membered heterocycle in the middle, combined with a properly substituted C(2)‐methyl benzimidazole on the right‐hand side were required to achieve potency, microsomal stability, and exposure upon oral dosing. A compound (PTC‐02) with acceptable pharmacological properties and efficacious in vivo in several tumor animal models was identified. [ABSTRACT FROM AUTHOR]

Abstract Electromagnetic fields (EMF) are increasing in popularity as a safe and non-invasive therapy. On the one hand, it is widely acknowledged that EMF can regulate the proliferation and differentiation of stem cells, promoting the undifferentiated cells capable of osteogenesis, angiogenesis, and chondroblast differentiation to achieve bone repair purpose. On the other hand, EMF can inhibit tumor stem cells proliferation and promote apoptosis to suppress tumor growth. As an essential second messenger, intracellular calcium plays a role in regulating cell cycle, such as proliferation, differentiation and apoptosis. There is increasing evidence that the modulation of intracellular calcium ion by EMF leads to differential outcomes in different stem cells. This review summarizes the regulation of channels, transporters, and ion pumps by EMF-induced calcium oscillations. It furtherly discusses the role of molecules and pathways activated by EMF-dependent calcium oscillations in promoting bone and cartilage repair and inhibiting tumor stem cells growth.

Abstract Background Gonadotrophic pituitary adenoma is a major subtype of pituitary adenoma in the sellar region, but it is rarely involved in the hypersecretion of hormones into blood; thus, it is commonly regarded as “non-functioning.” Its tumorigenic mechanisms remain unknown. The aim of this study was to identify human gonadotrophic pituitary adenoma stem cells (hPASCs) and explore the underlying gene expression profiles. In addition, the potential candidate genes involved in the invasive properties of pituitary adenoma were examined. Methods The hPASCs from 14 human gonadotrophic pituitary adenoma clinical samples were cultured and verified via immunohistochemistry. Genetic profiling of hPASCs and the matched tumor cells was performed through RNA-sequencing and subjected to enrichment analysis. By aligning the results with public databases, the candidate genes were screened and examined in invasive and non-invasive gonadotrophic pituitary adenomas using Real-time polymerase chain reaction. Results The hPASCs were successfully isolated and cultured from gonadotrophic pituitary adenoma in vitro, which were identified as positive for generic stem cell markers (Sox2, Oct4, Nestin and CD133) via immunohistochemical staining. The hPASCs could differentiate into the tumor cells expressing follicle-stimulating hormone in the presence of fetal bovine serum in the culture medium. Through RNA-sequencing, 1352 differentially expressed genes were screened and identified significantly enriched in various gene ontologies and important pathways. The expression levels of ANXA2, PMAIP1, SPRY2, C2CD4A, APOD, FGF14 and FKBP10 were significantly upregulated while FNDC5 and MAP3K4 were downregulated in the invasive gonadotrophic pituitary adenomas compared to the non-invasive ones. Conclusion Genetic profiling of hPASCs may explain the tumorigenesis and invasiveness of gonadotrophic pituitary adenoma. ANXA2 may serve as a potential therapeutic target for the treatment of gonadotrophic pituitary adenoma.

Objective: Research has suggested that tumor-initiating tumor stem cells are derived from normal stem cells and that tumor cells undergo progressive de-differentiation to achieve a stem cell-like state. Tumor stem cells are characterized by high proliferation ability, high plasticity, expression of multi-drug resistance proteins, and the ability to seed new tumors. Octamer-binding transcription factor 4 (Oct-4) and its activation targets are overexpressed in the tumor stem cells of various types of tumors, and this expression is associated with the pathogenesis, development, and poor prognosis of tumors. The primary objective of this study was to test if a stably transfected with Oct-4 gene cell line, RL95-2/Oct-4, has the characteristics of tumor stem cells. Materials and methods: Human endometrial carcinoma cells (RL95-2) were transfected with a plasmid carrying genes for Oct-4 and green fluorescent protein (GFP). The stably transfected cells, RL95-2/Oct-4, were selected using G418 and observed to express the GFP reporter gene under the control of the Oct-4 promoter. GFP expression levels of RL95-2/Oct-4 cells were measured using flow cytometry. The proliferation potential of cells was determined according to cumulative population doubling and colony-formation efficiency. Gene expression was analyzed using reverse transcription-polymerase chain reaction. Results: RL95-2/Oct-4 cells not only exhibited increased expression of the three most important stem cell genes, Oct-4, Nanog, and Sox2, but also had increased expression of the endometrial tumor stem cell genes CD133 and ALDH1. Furthermore, enhanced expression of these genes in the RL95-2/Oct-4 cells was associated with higher colony-forming ability and growth rate than in parental RL95-2 cells. We also observed that cisplatin induced less cell death in RL95-2/Oct-4 cells than in RL95-2 cells, indicating that RL95-2/Oct-4 cells were more resistant to chemotherapeutic agents. Conclusion: The study findings contribute to investigate the effects of Oct-4 on tumor stem cell origins.

Electromagnetic fields (EMF) are increasing in popularity as a safe and non-invasive therapy. On the one hand, it is widely acknowledged that EMF can regulate the proliferation and differentiation of stem cells, promoting the undifferentiated cells capable of osteogenesis, angiogenesis, and chondroblast differentiation to achieve bone repair purpose. On the other hand, EMF can inhibit tumor stem cells proliferation and promote apoptosis to suppress tumor growth. As an essential second messenger, intracellular calcium plays a role in regulating cell cycle, such as proliferation, differentiation and apoptosis. There is increasing evidence that the modulation of intracellular calcium ion by EMF leads to differential outcomes in different stem cells. This review summarizes the regulation of channels, transporters, and ion pumps by EMF-induced calcium oscillations. It furtherly discusses the role of molecules and pathways activated by EMF-dependent calcium oscillations in promoting bone and cartilage repair and inhibiting tumor stem cells growth. [ABSTRACT FROM AUTHOR]

Background: Effective anti-tumor immune responses are mediated by T cells and require organized, spatially coordinated interactions within the tumor microenvironment (TME). Understanding coordinated T-cell-behavior and deciphering mechanisms of radiotherapy resistance mediated by tumor stem cells will advance risk stratification of oropharyngeal cancer (OPSCC) patients treated with primary chemoradiotherapy (RCTx). Methods: To determine the role of CD8 T cells (CTL) and tumor stem cells for response to RCTx, we employed multiplex immunofluorescence stains on pretreatment biopsy specimens from 86 advanced OPSCC patients and correlated these quantitative data with clinical parameters. Multiplex stains were analyzed at the single-cell level using QuPath and spatial coordination of immune cells within the TME was explored using the R-package Spatstat. Results: Our observations demonstrate that a strong CTL-infiltration into the epithelial tumor compartment (HR for overall survival, OS: 0.35; p<0.001) and the expression of PD-L1 on CTL (HR: 0.36; p<0.001) were both associated with a significantly better response and survival upon RCTx. As expected, p16 expression was a strong predictor of improved OS (HR: 0.38; p=0.002) and correlated with overall CTL infiltration (r: 0.358, p<0.001). By contrast, tumor cell proliferative activity, expression of the tumor stem cell marker CD271 and overall CTL infiltration, regardless of the affected compartment, were not associated with response or survival. Conclusion: In this study, we could demonstrate the clinical relevance of the spatial organization and the phenotype of CD8 T cells within the TME. In particular, we found that the infiltration of CD8 T cells specifically into the tumor cell compartment was an independent predictive marker for response to chemoradiotherapy, which was strongly associated with p16 expression. Meanwhile, tumor cell proliferation and the expression of stem cell markers showed no independent prognostic effect for patients with primary RCTx and thus requires further study. [ABSTRACT FROM AUTHOR]

Glioblastoma is a rapidly progressing tumor quite resistant to conventional treatment. These features are currently assigned to a self-sustaining population of glioblastoma stem cells. Anti-tumor stem cell therapy calls for a new means of treatment. In particular, microRNA-based treatment is a solution, which in turn requires specific carriers for intracellular delivery of functional oligonucleotides. Herein, we report a preclinical in vitro validation of antitumor activity of nanoformulations containing antitumor microRNA miR-34a and microRNA-21 synthetic inhibitor and polycationic phosphorus and carbosilane dendrimers. The testing was carried out in a panel of glioblastoma and glioma cell lines, glioblastoma stem-like cells and induced pluripotent stem cells. We have shown dendrimer-microRNA nanoformulations to induce cell death in a controllable manner, with cytotoxic effects being more pronounced in tumor cells than in non-tumor stem cells. Furthermore, nanoformulations affected the expression of proteins responsible for interactions between the tumor and its immune microenvironment: surface markers (PD-L1, TIM3, CD47) and IL-10. Our findings evidence the potential of dendrimer-based therapeutic constructions for the anti-tumor stem cell therapy worth further investigation. [ABSTRACT FROM AUTHOR]

Lung cancer is the leading cause of cancer-related death worldwide. Its high mortality is partly due to chronic inflammation that accompanies the disease and stimulates cancer progression. In this review, we analyzed recent studies and highlighted the role of the epithelial–mesenchymal transition (EMT) as a link between inflammation and lung cancer. In the inflammatory tumor microenvironment (iTME), fibroblasts, macrophages, granulocytes, and lymphocytes produce inflammatory mediators, some of which can induce EMT. This leads to increased invasiveness of tumor cells and self-renewal of cancer stem cells (CSCs), which are associated with metastasis and tumor recurrence, respectively. Based on published data, we propose that inflammation-induced EMT may be a potential therapeutic target for the treatment of lung cancer. This prospect is partially realized in the development of EMT inhibitors based on pentacyclic triterpenoids (PTs), described in the second part of our study. PTs reduce the metastatic potential and stemness of tumor cells, making PTs promising candidates for lung cancer therapy. We emphasize that the high diversity of molecular mechanisms underlying inflammation-induced EMT far exceeds those that have been implicated in drug development. Therefore, analysis of information on the relationship between the iTME and EMT is of great interest and may provide ideas for novel treatment approaches for lung cancer.

The article presents the discussion on relationship between S1PR expressions and patient survival and clinical manifestations. Topics include predicting the relationship between S1PRs expression levels and patient survival using the univariate Cox proportional hazard regression model; and S1P being produced through the conversion of ceramide into sphingosine by ceramidase, followed by the phosphorylation of sphingosine-by-sphingosine kinase (SK).

The purpose of the study was to mine, compile and analyze the published data on breast cancer (BC) systematization, diagnosis and treatment. In the current review, modern approaches in BC subtypes diagnosis based on genomic profiling, miRNA expression pattern analysis, SNP analysis in BRCA1 and BRCA2 genes, as well as proteomic mapping as essential components of the disease peculiarities improving the prognostic outcome were compiled and analyzed. Further, tumor-initiating stem-like cells as a factor affecting both prognosis and treatment choice for BC are considered and evaluated. And finally, modern principles of enhancing tumor sensitivity to therapeutic effects of anticancer drugs, which comprise the use of cytostatics in condensed modes, combining drugs, which exert different mechanisms of cytotoxicity, as well as the introduction of new chemotherapy drugs into therapeutic practice, including those targeted against the common metabolic pathways both in stem-like and committed breast cancer cells, are compiled and discussed. The analysis indicates that the current paradigm in BC treatment is development and implementation of the newest methods for diagnosis of BC sybtypes, which, being combined with those already implemented, would allow the administration of treatment according to the individual peculiarities of a tumor.

Studying on subclonal evolution of cancer stem cells can help illustrate how the immune system recognizes tumor cells, leading to subclonal treatment by immune-based therapies. Here, we discuss that cancer subclones derived from the patient's head and neck squamous cell carcinoma tumor stem cells can be used for the screening of personalized antitumor immunotherapy and chemotherapy, to maximize benefits and to minimize the adversary effects, toward personalized or precision medicine. We propose a "wait-and-watch" scheme for monitoring a lifetime cancer stem cell subclonal development evolved with local environments to cancer.

Background. Gastric cancer is the second leading cause of cancer-related death due to advanced disease. A special role in the pathogenesis and metastasis of the tumor is assigned to tumor stem cells (TSC ), responsible for resistance to chemotherapy and radiotherapy and causing tumor progression.Objective: to determine the CD 44 and CD 133 markers of TSC in tumor tissues of non-metastatic and metastatic gastric cancer using the immunohistochemical method.Material and Methods. A prospective study of tumors in patients with gastric cancer was conducted: Group 1 – 20 people with T3–4aN0–3M0G2 tumor, average age 58.9 ± 9.7; Group 2 – 20 people with T3–4aN0–3M1G2 tumor, with metastases in the peritoneum, average age 53.4 ± 11.9. The expression of CD 44 and CD 133 in the tumor tissue was determined by immunohistochemistry.Results. Differences were found in the number of tumor cells expressing the CD 44 marker in the presence and absence of metastases in patients with gastric cancer – their number was 10.0 ± 3.08 and 6.0 ± 2.3, respectively. The CD 133 molecule was detected in 100 % of cases having metastases, while in cases having no metastases, the marker was detected only in 80 % of cases. The average percentage of CD 133 + cells was 21.3 ± 11.6 % in patients with metastatic gastric cancer and 10.0 ± 2.4 % in patients having no metastases.Conclusion. The degree of expression of the CD 44 and CD 133 markers had characteristic differences in patients with gastric cancer, which can be used further to explain the results of the treatment and the prognosis of the disease.

This research aims to explore the mechanism by which microRNAs may regulate the biological behavior of tumor cells in ALDH1+ fibrosarcoma. We identified differentially expressed miRNAs in ALDH + NMFH-1 cells, screened genes related to sarcoma metastasis in the TCGA database, and finally obtained key genes regulated by miRNAs that are involved in metastasis. The function and mechanism of these key genes were then validated at the cellular level. Using the ULCAN database, a significant correlation was found between hsa-mir-206 and mortality in sarcoma patients. WGCNA analysis identified 352 genes related to tumor metastasis. Through Venn diagrams, we obtained 15 metastasis-related genes regulated by hsa-mir-206. Survival analysis showed that SYNPO2 expression is significantly correlated with survival rate and is significantly underexpressed in multiple tumors. SYNPO2 showed a negative correlation with macrophages and a positive correlation with CD8+ T cells. After inhibiting the expression of hsa-mir-206 with siRNA plasmids, the mRNA expression of SYNPO2 was significantly upregulated. The results of CCK8 assay, scratch assay, and transwell assay showed that the proliferation and migration ability of NFMH-1 cells were promoted after SYNPO2 was inhibited. ALDH1+ tumor stem cells promote the proliferation and invasion of malignant fibrous histiocytoma cells by inhibiting SYNPO2 through hsa-mir-206. • SYNPO2 expression was low in many tumors. • SYNPO2 was negatively correlated with macrophages in the immune microenvironment. • Hsa-mir-206 promotes the progression of MFH by inhibiting SYNPO2 expression. [ABSTRACT FROM AUTHOR]

Liver cancer, one of the most common types of cancer worldwide, accounts for millions of cases annually. With its multi-target and wide-ranging therapeutic effects, traditional Chinese medicine has emerged as a potential approach for treating various tumors. Codonopsis pilosula , a traditional herb, is known for its anti-inflammatory and antioxidant properties. In this study, we investigated the potential molecular mechanisms of Codonopsis pilosula in regulating the inhibition of CDK1 and the modulation of PDK1/β-catenin, which are involved in hepatocellular carcinoma growth and metastasis. Firstly, we screened the active chemical constituents of Codonopsis pilosula and identified their respective target proteins using the Herb database. Then, we applied the GeneCards database and transcriptome sequencing analysis to screen for critical genes associated with the occurrence and development of liver cancer. The intersection of the target proteins and disease-related genes was used to determine the potential targets of Codonopsis pilosula in hepatocellular carcinoma. Protein-protein interaction analysis and GO/KEGG analysis were subsequently performed to uncover the pathways through which Codonopsis pilosula acts on liver cancer. The Huh-7 cell line, exhibiting the highest sensitivity to Codonopsis pilosula polysaccharide solution (CPP) intervention, was chosen for subsequent studies. Cell viability was evaluated using the CCK-8 assay, colony formation assay was conducted to determine cell proliferation capacity, flow cytometry was used to analyze cell cycle, TUNEL staining was performed to assess cell apoptosis, scratch assay was carried out to evaluate cell migration ability, the expression of EMT-related proteins was detected and analyzed, and cell sphere formation assay was conducted to investigate cell stemness. Finally, a liver cancer animal model was established, and different doses of CPP were administered via gavage the next day. The expression levels of CDK1, PDK1, and β-catenin in mouse liver tissues were detected and analyzed, immunohistochemistry staining was performed to assess the expression of tumor cell proliferation-related proteins Ki67 and PCNA in mouse xenografts, and TUNEL staining was carried out to evaluate cell apoptosis in mouse liver tissues. After intervention with CDK1 expression, the expression levels of CDK1, PDK1, and β-catenin proteins and mRNA in each group of cells were detected using Western blot and RT-qPCR. Through network pharmacology analysis, transcriptome sequencing, and bioinformatics analysis, 35 target genes through which Codonopsis pilosula acts on liver cancer were identified. Among them, CDK1, with the highest degree in the PPI network, was considered an essential target protein for Codonopsis pilosula in treating liver cancer. In vitro cell experiments revealed that CPP could inhibit the expression of CDK1/PDK1/β-catenin signaling axis factors, suppress cell proliferation, decrease cell migration ability, influence the EMT process, and reduce cell stemness by inhibiting CDK1 and affecting the PDK1/β-catenin signaling axis. Similarly, in vivo experiments demonstrated that CPP could regulate the CDK1/PDK1/β-catenin signaling axis, inhibit tumor growth, and induce cell apoptosis. Codonopsis pilosula may inhibit hepatocellular carcinoma growth by suppressing CDK1 and affecting the PDK1/β-catenin signaling axis, limiting cell EMT and reducing cell stemness. These findings provide insights into the potential therapeutic role of Codonopsis pilosula in liver cancer. [Display omitted] [ABSTRACT FROM AUTHOR]

Glioblastoma is a rapidly progressing tumor quite resistant to conventional treatment. These features are currently assigned to a self-sustaining population of glioblastoma stem cells. Anti-tumor stem cell therapy calls for a new means of treatment. In particular, microRNA-based treatment is a solution, which in turn requires specific carriers for intracellular delivery of functional oligonucleotides. Herein, we report a preclinical in vitro validation of antitumor activity of nanoformulations containing antitumor microRNA miR-34a and microRNA-21 synthetic inhibitor and polycationic phosphorus and carbosilane dendrimers. The testing was carried out in a panel of glioblastoma and glioma cell lines, glioblastoma stem-like cells and induced pluripotent stem cells. We have shown dendrimer-microRNA nanoformulations to induce cell death in a controllable manner, with cytotoxic effects being more pronounced in tumor cells than in non-tumor stem cells. Furthermore, nanoformulations affected the expression of proteins responsible for interactions between the tumor and its immune microenvironment: surface markers (PD-L1, TIM3, CD47) and IL-10. Our findings evidence the potential of dendrimer-based therapeutic constructions for the anti-tumor stem cell therapy worth further investigation.

Tumor cells with stem cell properties are considered to play major roles in promoting the development and malignant behavior of aggressive cancers. Therapeutic strategies that efficiently eradicate such tumor stem cells are of highest clinical need. Herein, we performed the validation of the polycationic phosphorus dendrimer-based approach for small interfering RNAs delivery in in vitro stem-like cells as models. As a therapeutic target, we chose Lyn, a member of the Src family kinases as an example of a prominent enzyme class widely discussed as a potent anti-cancer intervention point. Our selection is guided by our discovery that Lyn mRNA expression level in glioma, a class of brain tumors, possesses significant negative clinical predictive value, promoting its potential as a therapeutic target for future molecular-targeted treatments. We then showed that anti-Lyn siRNA, delivered into Lyn-expressing glioma cell model reduces the cell viability, a fact that was not observed in a cell model that lacks Lyn-expression. Furthermore, we have found that the dendrimer itself influences various parameters of the cells such as the expression of surface markers PD-L1, TIM-3 and CD47, targets for immune recognition and other biological processes suggested to be regulating glioblastoma cell invasion. Our findings prove the potential of dendrimer-based platforms for therapeutic applications, which might help to eradicate the population of cancer cells with augmented chemotherapy resistance. Moreover, the results further promote our functional stem cell technology as suitable component in early stage drug development. [ABSTRACT FROM AUTHOR]

Abstract Background/aims The expression levels of long non-coding RNA XIST are significantly associated with paclitaxel (Pac) sensitivity in ovarian cancer, but the mechanism of action remains unclear. Therefore, this experimental design was based on lncRNA XIST analysis to regulate the effect of XIST on the tumor stem cell and paclitaxel sensitivity in ovarian cancer. Methods Sphere assay and fluorescence activated cell sorting (FACS) were used to determine the expression levels of XIST and sensitivity to paclitaxel treatment. The effect of the proliferation was detected by MTT assay. Target gene prediction and screening, luciferase reporter assays were used to validate downstream target genes for lncRNA XIS and KMT2C. The expression of KMT2C was detected by RT-qPCR and Western blotting. RT-qPCR was used to detect the expression of cancer stem cell-associated genes SOX2, OCT4 and Nanog. The tumor changes in mice were detected by in vivo experiments in nude mice. Results There was an inverse correlation between the expression of XIST and cancer stem cell (CD44 + /CD24−) population. XIST promoted methylation of histone H3 methylation at lysine 4 by enhancing the stability of lysine (K)-specific methyltransferase 2C (KMT2C) mRNA. XIST acted on the stability of KMT2C mRNA by directly targeting miR-93-5p. Overexpression of miR-93-5p can reverse the XIST overexpression-induced KMT2C decrease and sphere number increase. Overexpression of KMT2C inhibited XIST silencing-induced proliferation of cancer stem cells, and KMT2C was able to mediate paclitaxel resistance induced by XIST in ovarian cancer. The study found that XIST can affect the expression of KMT2C in the ovarian cancer via targeting miR-93-5p. Conclusion XIST promoted the sensitivity of ovarian cancer stem cells to paclitaxel in a KMT2C-dependent manner.

Objective To explore the method for in vitro culture of an organoid model of nasopharyngeal carcinoma (NPC) and examine its in vitro chemosensitivity profile. Methods Fresh specimens of NPC tissues were obtained from clinical patients during nasopharyngoscopic biopsy or nasal endoscopic surgeries. The tumor tissues were cut into pieces, digested with mixed digestive juice and filtered. The NPC cells were isolated by centrifugation, resuspended with Matrix gel and AMDM/F12, and inoculated in a Petri dish for three-dimensional culture of the organoids. Paraffin sections of the NPC organoids cultured for 5 to 7 d were prepared for morphological examination and immunohistochemistry for Ki67 and CD133, CD44 immunofluorescence assay, and EBER in situ hybridization. The NPC organoids cultured for 5 d were tested for chemosensitivity to paclitaxel, cisplatin, carboplatin, gemcitabine and vinorelbine by assessing the cell viability with neutral red staining following treatments with the drugs. Results The cultured NPC organoids showed obvious nuclear atypia, which was consistent with that of the source NPC tissues. The NPC organoids were strongly positive for CD133 and CD44, suggesting the enrichment of tumor stem cells in the organoids. Nearly 30% of the cells in the organoids were positive for Ki67, indicating the proliferative capacity of the organoids. Chemosensitivity tests showed that the NPC organoids were highly sensitive to carboplatin, cisplatin and vinorelbine, and moderately sensitive to gemcitabine, but with a low sensitivity to tigio. Conclusion We successfully established an in vitro culture system of NPC organoids, which can serve as a new NPC model for testing drug sensitivities.

Objective To investigate the effects and mechanism of salinomycin on the proliferation and apoptosis of breast cancer stem cells. Methods The MCF-7 cells were cultured in vitro to form microspheres, and the third-generation microspheres were added to CD44-FITC and CD24-PE, respectively. The percentage of breast stem cells was detected by flow cytometry. The third-generation microspheric cells were treated with salinomycin（0, 0. 5, 2, 5, 7, and 9 µmol/L） for 12, 24 and 48 h, respectively. MTT assay was used to detect the effect of salinomycin on the proliferation of breast cancer stem cells. The third-generation microspheric cells were treated with salinomycin（0, 2. 5, 5, and 9 µmol/L）for 24 h, and the inverted phase-contrast microscope was used to observe the morphological change of breast cancer stem cells. The third-generation microspheric cells were treated with salinomycin（0, 2, 5, and 9 µmol/L）for 24 h, and FITC-Annexin V/PI apoptosis detection kit and PI staining assay were used to detect the apoptosis rate and cell cycle of the breast cancer stem cells. The third-generation microspheric cells were treated with salinomycin（0, 0. 5, 2, 5, and 9 µmol/L）for 24 h, and Western blotting was used to detect the expression levels of apoptosis-related proteins Caspase-3, Caspase-9, PARP, β-catenin, Survivin, Bcl-2, and Bax. Results Flow cytometry showed that the ratio of CD44+ /CD24-/low breast cancer stem cells in the microspheres was 87. 0%±0. 4%, which was 40. 1%±1. 0% in the MCF-7 cells, with statistically significant difference（P<0. 05）. MTT assay showed that different concentrations of salinomycin could inhibit the activity of breast cancer stem cells, with a concentration- and time-dependent manner（P<0. 05）. The inverted phase-contrast microscope showed that breast cancer microspheres gradually depolymerized after the intervention of salinomycin, the density decreased, the cell size was different and extremely irregular, and granules appeared in the tumor cells, the cells had edema, pyknosis, and cell debris. As the concentration of salinomycin increased, the apoptosis became more and more significant. The apoptosis rate significantly increased as the concentration of salinomycin increased, which was probably accompanied by cell cycle arrest. As the concentration of salinomycin increased, the levels of Caspase-3, Caspase-9, PARP active fragment, and Bax increased, but the expression levels of β-catenin, Survivin and Bcl-2 decreased（all P<0. 05）. Conclusion Salinomycin could inhibit the proliferation and promote apoptosis of breast cancer stem cells probably by inhibiting β-catenin-Survivin-Caspase-3 pathway and interfering with the activity of Wnt signaling pathway. [ABSTRACT FROM AUTHOR]

ObjectivesTo identify key genes involved in vascular invasion in hepatocellular carcinoma (HCC), to describe their regulatory mechanisms, and to explore the immune microenvironment of HCC.MethodologyIn this study, the genome, transcriptome, and immune microenvironment of HCC were assessed by using multi-platform data from The Cancer Genome Atlas (n = 373) and GEO data (GSE149614). The key regulatory networks, transcription factors and core genes related to vascular invasion and prognosis were explored based on the CE mechanism. Survival analysis and gene set enrichment were used to explore pathways related to vascular invasion. Combined with single-cell transcriptome data, the distribution of core gene expression in various cells was observed. Cellular communication analysis was used to identify key cells associated with vascular invasion. Pseudo-temporal locus analysis was used to explore the regulation of core genes in key cell phenotypes. The influence of core genes on current immune checkpoint therapy was evaluated and correlations with tumor stem cell scores were explored.ResultsWe obtained a network containing 1,249 pairs of CE regulatory relationships, including 579 differential proteins, 28 non-coding RNAs, and 37 miRNAs. Three key transcription factors, ILF2, YBX1, and HMGA1, were identified, all regulated by HCG18 lncRNA. ScRNAseq showed that HCG18 co-localized with macrophages and stem cells. CIBERSORTx assessed 22 types of immune cells in HCC and found that HCG18 was positively correlated with M0 macrophages, while being negatively correlated with M1 and M2 macrophages, monocytes, and dendritic cells. Cluster analysis based on patient prognosis suggested that regulating phenotypic transformation of macrophages could be an effective intervention for treating HCC. At the same time, higher expression of HCG18, HMGA1, ILF2, and YBX1 was associated with a higher stem cell score and less tumor differentiation. Pan cancer analysis indicated that high expression of HCG18 implies high sensitivity to immune checkpoint therapy.ConclusionHCG18 participates in vascular invasion of HCC by regulating macrophages and tumor stem cells through three key transcription factors, YBX1, ILF2, and HMGA1.

We have previously generated a mouse model (Ptch1+/−/Tis21KO), which displays high frequency spontaneous medulloblastoma, a pediatric tumor of the cerebellum. Early postnatal cerebellar granule cell precursors (GCPs) of this model show, in consequence of the deletion of Tis21 , a defect of the Cxcl3-dependent migration. We asked whether this migration defect, which forces GCPs to remain in the proliferative area at the cerebellar surface, would be the only inducer of their high frequency transformation. In this report we show, by further bioinformatic analysis of our microarray data of Ptch1+/−/Tis21KO GCPs, that, in addition to the migration defect, they show activation of the PI3K/AKT/mTOR pathway, as the mRNA levels of several activators of this pathway (e.g., Lars , Rraga , Dgkq , Pdgfd) are up-regulated, while some inhibitors (e.g. Smg1) are down-regulated. No such change is observed in the Ptch1+/− or Tis21KO background alone, indicating a peculiar synergy between these two genotypes. Thus we investigated, by mRNA and protein analysis, the role of PI3K/AKT/mTOR signaling in MBs and in nodules from primary Ptch1+/−/Tis21KO MB allografted in the flanks of immunosuppressed mice. Activation of the PI3K/AKT/mTOR pathway is seen in full-blown Ptch1+/−/Tis21KO MBs, relative to Ptch1+/−/Tis21WT MBs. In Ptch1+/−/Tis21KO MBs we observe that the proliferation of neoplastic GCPs increases while apoptosis decreases, in parallel with hyper-phosphorylation of the mTOR target S6, and, to a lower extent, of AKT. In nodules derived from primary Ptch1+/−/Tis21KO MBs, treatment with MEN1611, a novel PI3K inhibitor, causes a dramatic reduction of tumor growth, inhibiting proliferation and, conversely, increasing apoptosis, also of tumor CD15+ stem cells, responsible for long-term relapses. Additionally, the phosphorylation of AKT, S6 and 4EBP1 was significantly inhibited, indicating inactivation of the PI3K/AKT/mTOR pathway. Thus, PI3K/AKT/mTOR pathway activation contributes to Ptch1+/−/Tis21KO MB development and to high frequency tumorigenesis, observed when the Tis21 gene is down-regulated. MEN1611 could provide a promising therapy for MB, especially for patient with down-regulation of Btg2 (human ortholog of the murine Tis21 gene), which is frequently deregulated in Shh-type MBs. [ABSTRACT FROM AUTHOR]

Objective To determine the efficiency of autofluorescence technique in screening of glioma stem cells (GSCs). Methods Since GSCs favor riboflavin, the agent was added to the culture medium of normal glioma stem cells. Then flow cytometry was employed to screen glioma stem cells with autofluorescence. Subsequently, the proliferation of the obtained cells was detected by CCK-8 assay. Finally, a mouse model of xenograft was established to observe the survive and tumor size and weight. The expression of Ki67, PCNA and Nestin in the tumor mass was detected by immunohistochemical assay. Results Glioma stem cells with autofluorescence were successfully screened out by flow cytometry. CCK-8 assay indicated that the proliferation of autofluorescence glioma stem cells was significantly stronger (P < 0.01). In vitro tumor-bearing experiments suggested that mice with xenograft of fluorescent stem cells had significantly reduced survival time and increased tumor volume and weight (P < 0.01). Immunohistochemical assay showed that the expression levels of Ki67, PCNA and Nestin in the tumor mass were significantly increased (P < 0.05). The proliferation and malignancy of the autofluorescence GSCs were stronger than glioma stem GL261 cells screened by CD133+ labeling. The CD133- GSCs with higher malignancy and invasion were also screened out with this method. Conclusion Autofluorescence technique can screen GSCs with high malignancy

Glioblastoma (GBM) is the most common and devastating primary cancer of the central nervous system in adults. High grade gliomas are able to modify and respond to the brain microenvironment. When GBM tumors infiltrate the Subventricular zone (SVZ) they have a more aggressive clinical presentation than SVZ-distal tumors. We suggest that cerebrospinal fluid (CSF) contact contributes to enhance GBM malignant characteristics in these tumors. We evaluated the impact of human CSF on GBM, performing a transcriptome analysis on human primary GBM cells exposed to CSF to measure changes in gene expression profile and their clinical relevance on disease outcome. In addition we evaluated the proliferation and migration changes of CSF-exposed GBM cells in vitro and in vivo. CSF induced transcriptomic changes in pathways promoting cell malignancy, such as apoptosis, survival, cell motility, angiogenesis, inflammation, and glucose metabolism. A genetic signature extracted from the identified transcriptional changes in response to CSF proved to be predictive of GBM patient survival using the TCGA database. Furthermore, CSF induced an increase in viability, proliferation rate, and self-renewing capacity, as well as the migratory capabilities of GBM cells in vitro. In vivo, GBM cells co-injected with human CSF generated larger and more proliferative tumors compared to controls. Taken together, these results provide direct evidence that CSF is a key player in determining tumor growth and invasion through the activation of complex gene expression patterns characteristic of a malignant phenotype. These findings have diagnostic and therapeutic implications for GBM patients. The changes induced by CSF contact might play a role in the increased malignancy of SVZ-proximal GBM.

Glioblastoma (GBM) is the most common and devastating primary cancer of the central nervous system in adults. High grade gliomas are able to modify and respond to the brain microenvironment. When GBM tumors infiltrate the Subventricular zone (SVZ) they have a more aggressive clinical presentation than SVZ-distal tumors. We suggest that cerebrospinal fluid (CSF) contact contributes to enhance GBM malignant characteristics in these tumors. We evaluated the impact of human CSF on GBM, performing a transcriptome analysis on human primary GBM cells exposed to CSF to measure changes in gene expression profile and their clinical relevance on disease outcome. In addition we evaluated the proliferation and migration changes of CSF-exposed GBM cells in vitro and in vivo. CSF induced transcriptomic changes in pathways promoting cell malignancy, such as apoptosis, survival, cell motility, angiogenesis, inflammation, and glucose metabolism. A genetic signature extracted from the identified transcriptional changes in response to CSF proved to be predictive of GBM patient survival using the TCGA database. Furthermore, CSF induced an increase in viability, proliferation rate, and self-renewing capacity, as well as the migratory capabilities of GBM cells in vitro. In vivo , GBM cells co-injected with human CSF generated larger and more proliferative tumors compared to controls. Taken together, these results provide direct evidence that CSF is a key player in determining tumor growth and invasion through the activation of complex gene expression patterns characteristic of a malignant phenotype. These findings have diagnostic and therapeutic implications for GBM patients. The changes induced by CSF contact might play a role in the increased malignancy of SVZ-proximal GBM. [ABSTRACT FROM AUTHOR]

Previously, from the adhesive cell line of Zajdela rat ascitic hepatoma, we obtained daughter sublines of two types (holoclonal and meroclonal), the cells of which differed in morphology (fibroblast- and epithelium-like, respectively), clonogenicity in tests in vitro, and tumorigenicity in vivo. To identify the potential role of Zajdela hepatoma adherent cells in processes of epithelial–mesenchymal transition (EMT) and metastasis, we compared all its sublines with monolayer lines of other hepatocellular tumors by the parameters that determine invasive and migratory properties of the cells. We have established that the cells of the holoclonal sublines are characterized by an increased activity of matrix metalloproteinase (MMP) 1, individual type of migration, and high motility rate as compared with the cells of other lines. The cells of all monolayer lines of Zajdela hepatoma secreted active forms of MMP-9 and translocated the intracellular domain of epithelial cell adhesion molecule (EpCAM) to their nucleus, which indicates the acquisition of an invasive phenotype by the cells and activation of Wnt/β-catenin signaling pathway. Our results indicate that the clonal sublines that we obtained from Zajdela ascitic hepatoma are consisted of the cells in transitional states between the epithelial and mesenchymal phenotypes. [ABSTRACT FROM AUTHOR]

Background: The conserved stem cell signaling network canonical Wingless (WNT) plays important roles in development and disease. Aberrant activation of this pathway has been linked to tumor progression and resistance to therapy. Industry and academia have substantially invested in developing substances, which can efficiently and specifically block the WNT signaling pathway. However, a clear clinical proof of the efficacy of this approach is still missing. Studies on the metabolomics dysregulation of cancer cells have led to innovations in oncological diagnostics. In addition, modulation of cancer cell metabolome is at the base of promising clinical oncology trials currently underway. While onco-protein activation can have profound metabolic outcomes, the involvement of stem cell signals, such as the WNT pathway, in tumor cell metabolomics is yet insufficiently characterized. Material and methods: We determined live cell metabolism and bioenergetics in pathophysiological relevant, WNT-dependent glioblastoma stem cell (GSC) models. We quantified those parameters in cells with canonical WNT activity and in isogenic cells where WNT activity had been inhibited by short hairpin RNA against β-catenin. Furthermore, we applied computational analysis of RNA sequencing to verify our functional findings in independent GSCs cohorts. Results: The investigated collection of disease models allows the separation in tumors with low, moderate and high base line metabolic activity. Suppression of canonical WNT signaling led to significant reduction of total, mitochondrial, and glycolytic ATP production rates. Elevated canonical WNT transcription signature in GSCs positively correlated with transcription levels of mitochondrial ATP synthesis, whereas non-canonical WNT gene expression signature did not. Conclusion: The applied disease modeling technology allows the recapitulation of inter-tumoral heterogeneous metabolic properties of glioblastoma. Our data show for the first time that inhibition of canonical WNT signaling in alive GSCs functionally correlates with energy inhibition and glucose homeostasis. As this correlation occurs in GSCs from different transcriptional or epigenetic transcriptional subtypes, our results suggest that developing therapies directed against glycolysis/ATP-synthesis may be a promising strategy to overcome therapy resistance due to inter-tumoral heterogeneity and offers starting point to impair downstream signal WNT.

Abstract Background As a factor contributing to the tumor cell drug resistance, tumor microenvironment (TME) is being paid increasingly attention. However, the drug resistance of malignantly transformed cells in TME has rarely been revealed. This paper is designed to investigate the sensitivity of malignantly transformed cell line (ihDCTC) induced by glioma stem cells (GSCs) in TME to chemotherapeutic drugs. Methods (1) Establishment of ihDCTC cell line,The bone marrow cells from enhanced green fluorescent protein (EGFP) transgenic nude mice were employed to culture the dendritic cells (DCs) in vitro, which were then co-cultured with red fluorescence protein (RFP) transgenic GSCs (SU3) to obtain ihDCTC (2) Res and Cis were used to intervene in the growth of abovemetioned cell lines in vitro and Res treated in bearing ihDCTC tumor mice, followed by evaluating their drug sensitivity and changes in key signaling proteins via half maximal inhibitory concentration (IC50), tumor mass and immunostaining method. Results (1) ihDCTC could express CD11c and CD80 as well as possessed immortalized potential, heteroploid chromosomes and high tumorigenicity in nude mice in vivo. (2) At 24 h, 48 h and 72 h, the IC50 value of ihDCTC treated with Cis was 3.62, 3.25 and 2.10 times higher than that of SU3, while the IC50 value of ihDCTC treated with Res was 0.03, 0.47 and 1.19 times as much as that of SU3; (3) The xenograft mass (g) in vivo in the control, Res, Cis and Res + Cis groups were 1.44 ± 0.19, 0.45 ± 0.12, 0.94 ± 0.80 and 0.68 ± 0.35(x ± s) respectively. The expression levels of IL-6, p-STAT3 and NF-κB proteins in the xenograft tissue were significantly reduced only in the Res treatment group. Conclusion In vitro co-culture with GSC can induce the malignant transformation of bone marrow derived dendritic cells, on the one hand, ihDCTC shows higher drug resistance to the traditional chemotherapeutic drug Cis than GSCs, but, on the other hand, appears to be more sensitive to Res than GSCs. Therefore, our findings provide a broader vision not only for the further study on the correlation between TME and tumor drug resistance but also for the exploration of Res anti-cancer value.

• Induced pluripotent stem cell (iPSC) markers OCT4, SOX2, NANOG, KLF4 and c-MYC are expressed in Schwannoma. • The endothelium of the tumor microvessels of Schwannoma that express iPSC markers displays an endothelial progenitor cell phenotype. • We demonstrate two embryonic stem cell-like subpopulations: an OCT4+/SOX2+/NANOG+/KLF4+/c-MYC+/CD133+ subpopulation on the endothelium of tumor microvessels, and an OCT4-/SOX2+/NANOG-/KLF4+/c-MYC+/CD133+ subpopulation within Schwannoma. There is accumulating evidence of the presence of embryonic stem cell (ESC)-like cells in benign tumors. This study aimed to identify ESC-like cells in Schwannoma using the induced-pluripotent stem cell (iPSC) markers OCT4, SOX2, NANOG, KLF4 and c-MYC. Immunohistochemical (IHC) staining (n = 20) and RT-qPCR (n = 6) were performed on Schwannoma tissue samples (STS) to investigate protein and mRNA expression of these iPSC markers, respectively. Immunofluorescence (IF) staining was performed to investigate co-localization of the iPSC markers with CD34, α-SMA and CD133. IHC staining and RT-qPCR demonstrated protein and mRNA expression of all five iPSC markers, respectively. IF staining showed expression of SOX2, KLF4 and c-MYC on the tumor cells and the endothelium of the tumor microvessels which also expressed OCT4, while NANOG was exclusively expressed on the endothelium of the tumor microvessels. The OCT4+/CD34+ endothelium expressed CD133. We have identified a putative OCT4+/SOX2+/NANOG+/KLF4+/c-MYC+/CD133+ ESC-like subpopulation on the endothelium of tumor microvessels and an OCT4-/SOX2+/NANOG-/KLF4+/c-MYC+/CD133+ ESC-like subpopulation, within Schwannoma. [ABSTRACT FROM AUTHOR]

Adult stem cells are rare, undifferentiated cells found in all tissues of the body. Although normally kept in a quiescent, nondividing state, these cells can proliferate and differentiate to replace naturally dying cells within their tissue and to repair its wounds in response to injury. Due to their proliferative nature and ability to regenerate tissue, adult stem cells have the potential to treat a variety of degenerative diseases as well as aging. In addition, since stem cells are often thought to be the source of malignant tumors, understanding the mechanisms that keep their proliferative abilities in check can pave the way for new cancer therapies. While adult stem cells have had limited practical and clinical applications to date, several clinical trials of stem cell–based therapies are underway. This report details recent research presented at the New York Academy of Sciences on March 14, 2019 on understanding the factors that regulate stem cell activity and differentiation, with the hope of translating these findings into the clinic. [ABSTRACT FROM AUTHOR]

Tumor vascular endothelial cells play a pivotal in the tumor microenvironment, influencing the proliferation, invasion, and metastasis of tumor progression. The present study investigated a novel method for inducing the transformation of breast cancer stem cells into endothelial cells, providing a cellular model investigating anti-angiogenic mechanisms in vitro. The breast cancer cell line MCF-7 was used, and the expression of CD133 was initially detected using flow cytometry. CD133+ breast cancer cells were purified using immunomagnetic bead sorting technology, yielding an MCF-7CD133+ subpopulation. The proliferation ability of these cells was assessed using an MTT assay, while their microsphere formation ability was evaluated using a microsphere formation assay. Post-transformation in an optimized endothelial cell culture medium, expression of endothelial cell markers CD31 and CD105 were detected using flow cytometry. Endothelial cell tube formation assays and DiI-labeled acetylated low-density lipoprotein (DiI-Ac-LDL) assays were employed to analyze the endothelial cell function of the MCF-7CD133+ cells. MDM2/CEN12 gene amplification was detected through fluorescence in situ hybridization (FISH). The MCF-7 breast cancer cell line exhibited 1.7±0.3% trace cells expressing the stem cell surface marker CD133. After anti-CD133 immunomagnetic bead sorting, MCF-7CD133+ and MCF-7CD133- subpopulation cells were obtained, with CD133 expression rates of 85.6±2.8 and 0.18±0.08%, respectively. MTT assay results demonstrated that, after 7 days, the proliferation rate of MCF-7CD133+ cells was significantly higher compared with MCF-7CD133- cells. MCF-7CD133+ subpopulation cells displayed strong stem cell characteristics, growing in suspension in serum-free media and forming tumor cell spheres. In contrast, MCF-7CD133- cells failed to form microspheres. After culturing cells in endothelial cell differentiation and maintenance media, the percentage of MCF-7CD133+ cells before and after endothelial cell culture was 0.3±0.16 and 81.4±8.37% for CD31+ cells and 0.2±0.08 and 83.8±7.24% for CD105+ cells, respectively. Vascular-like structure formation and Ac-LDL phagocytosis with red fluorescence in the tube formation assays confirmed endothelial cell function in the MCF-7CD133+ cells. FISH was used to verify MDM2/CEN12 gene amplification in the induced MCF-7CD133+ cells, indicating tumor cell characteristics. The modified endothelial cell transformation medium effectively induced differentiated tumor stem cells to express vascular endothelial cell markers and exhibit endothelial functions, ideal for in vitro anti-angiogenesis research. [ABSTRACT FROM AUTHOR]

Aim: We have recently demonstrated the presence of putative tumor stem cells (TSCs) in World Health Organization (WHO) grade I meningioma (MG) localized to the microvessels, which expresses components of the renin-angiotensin system (RAS). The RAS is known to be dysregulated and promotes tumorigenesis in many cancer types, including glioblastoma. Cathepsins B, D, and G are isoenzymes that catalyze the production of angiotensin peptides, hence providing bypass loops for the RAS. This study investigated the expression of cathepsins B, D, and G in WHO grade I MG in relation to the putative TSC population we have previously demonstrated.Methods: 3,3-Diaminobenzidine (DAB) immunohistochemical (IHC) staining with antibodies for cathepsins B, D, and G was performed on WHO grade I MG tissue samples from 10 patients. Three of the MG samples subjected to DAB IHC staining underwent immunofluorescence (IF) IHC staining to investigate co-expression of each of these cathepsins using combinations of smooth muscle actin (SMA) and embryonic stem cell marker OCT4. NanoString mRNA expression (n = 6) and Western blotting (WB; n = 5) analyses, and enzyme activity assays (EAAs; n = 3), were performed on snap-frozen WHO grade I MG tissue samples to confirm transcriptional activation, protein expression, and functional activity of these proteins, respectively.Results: DAB IHC staining demonstrated expression of cathepsins B, D, and G in all 10 MG samples. NanoString mRNA expression and WB analyses showed transcriptional activation and protein expression of all three cathepsins, although cathepsin G was expressed at low levels. EAAs demonstrated that cathepsin B and cathepsin D were functionally active. IF IHC staining illustrated localization of cathepsin B and cathepsin D to the endothelium and SMA+ pericyte layer of the microvessels, while cathepsin G was localized to cells scattered within the interstitium, away from the microvessels.Conclusion: Cathepsin B and cathepsin D, and to a lesser extent cathepsin G, are expressed in WHO grade I MG. Cathepsin B and cathepsin D are enzymatically active and are localized to the putative TSC population on the microvessels, whereas cathepsin G was localized to cells scattered within the interstitium, These results suggest the presence of bypass loops for the RAS, within WHO grade I MG.

BACKGROUND: Lutein can inhibit proliferation and promote apoptosis in cancer cells of various origins. However, there are no reports on the effect and mechanism of lutein on the proliferation and apoptosis of gastric cancer stem cells. OBJECTIVE: To observe the effect of lutein on proliferation and apoptosis of gastric cancer stem cells and explore its possible mechanism. METHODS: Gastric cancer stem cells were obtained from human gastric cancer cell line SGC-7901 in vitro. Flow cytometry was used to identify cell surface markers CD44 and CD24. Human gastric cancer stem cells were treated with 0, 20, 40, 80, and 160 mmol/L lutein for 24, 48, and 72 hours, respectively. Cell proliferation activity was detected by cell counting kit-8 method, to determine the optimal concentration and action time of lutein. Human gastric cancer stem cells were then divided into four groups: control group, 80 mmol/L lutein group, insulin-like growth factor 1 group, lutein+insulin-like growth factor 1 group, and given the corresponding treatments for 48 hours. Flow cytometry was used to detect cell apoptosis. The expressions of PI3K and Akt mRNA were detected by quantitative real-time PCR, and the expressions of PI3K, p-PI3K, Akt and p-Akt proteins were detected by western blot assay. RESULTS AND CONCLUSION: (1) Gastric cancer stem cells derived from human gastric cancer SGC7901 cells cultured in vitro expressed CD44 and CD24. (2) Lutein at 80 and 160 mmol/L acting for 48 hours could achieve the best inhibitory effect (P < 0.05). As the half maximal inhibitory concentration (IC50) of lutein for 48 hours was 91.58 mmol/L, 80 mmol/L lutein acting for 48 hours was selected for subsequent experiments. (3) The proliferation activity of the cells was highest in the insulin-like growth factor 1 group and lowest in the lutein group, and there were significant differences between groups (P < 0.05). (4) The apoptotic rate was highest in the lutein group and lowest in the insulin-like growth factor 1 group, and there were significant differences between groups (P < 0.05). (5) The expressions of PI3K and Akt mRNA were highest in the lutein group and lowest in the insulin-like growth factor 1 group, and there were significant differences between groups (P < 0.05). (6) The expressions of p-PI3K and p-Akt protein in the lutein group were significantly lower than those in the control group and insulin-like growth factor 1 group, while the expressions of p-PI3K and p-Akt protein in the insulin-like growth factor 1 group were significantly higher than those in the other three groups (P < 0.05). These results suggest that lutein inhibits the proliferation and induces apoptosis of human gastric cancer stem cells by inhibiting the PI3K/Akt signaling pathway. [ABSTRACT FROM AUTHOR]

BACKGROUND: Malignant transformation of host-derived stromal cells in xenograft tumors has been reported, but little is known about the mechanisms of malignant transformation. OBJECTIVE: To investigate the malignant transformation of host-derived tumor stromal cells and to explore the possible mechanisms in an in vivo model of two-color fluorescent tracing. METHODS: Human glioma-initiating cells stably transfected with red fluorescent protein gene (GICs-RFP) were inoculated into nude mice expressing enhanced green fluorescent protein (EGFP). An in vivo model of two-color fluorescence tracer was established. The fluorescent expression of transplanted tumors was observed by confocal laser scanning. Flow cytometry was used to detect and classify various fluorescent cells, including EGFP cells, RFP cells and EGFP/RFP fusion cells. The fusion cells co-expressed EGFP/RFP and had malignant proliferation characteristics because of in vitro subcloning. Origin, surface markers and malignant features of the cells were identified in vitro. The tumorigenicity of fusion cells was verified by subcutaneous transplantation in nude mice. The study was approved by the Animal Ethics Committee of Soochow University (approval No. ECSU-201800090). RESULTS AND CONCLUSION: The tumorigenic rates of GICs-RFP in EGFP nude mice were 100% (14/14). Fusion cells were observed in the transplanted tumors of all the animal models. The fusion cells not only co-expressed EGFP and RFP, but also co-expressed GICs-RFP marker Nestin and bone marrow mesenchymal stem cell markers CD44, CD105 and CD29. Fusion cells showed high proliferative activity and more invasive and migratory characteristics in vitro as compared with GICs-RFP. The tumorigenicity of fusion cells (1×105 cells per mouse) in thymus-free nude mice was 100% (4/4). These results indicate that GICs-RFP spontaneously fuses with host-derived bone marrow mesenchymal stem cells and induces malignant transformation, which provides new evidence for two-color fluorescence tracing of heterogeneous tumor cell sources. [ABSTRACT FROM AUTHOR]

BACKGROUND: MicroRNA-9 (miR-9) exerts different effects in different types of tumors and at different stages of tumorigenesis, but its role in thyroid papillary carcinoma remains unclear. OBJECTIVE: To analyze the effects of miR-9 on the proliferation and migration of thyroid papillary cancer stem cells in vitro. METHODS: ALDH1 positive cells and ALDH1 negative cells were separated from human papillary thyroid cancer cells by flow cytometry. Expression of miR-9 mRNA was detected using reverse transcription PCR. ALDH1 positive cells in logarithmic growth phase were transfected with miR-9 mimetic, miR-9 inhibitor or miR mimetic control. After 48 hours, the transfection efficiency of miR-9 was detected by qRT-PCR; cell proliferation, apoptosis and migration were detected by MTT, TUNEL, and Transwell chamber assay, respectively. The expression of apoptosis-related proteins (Bcl-2 and Bax) and migration-related proteins (matrix metalloproteinase-2 and matrix metalloproteinase-9) was detected by western blot. RESULTS AND CONCLUSION: Successful transfections were confirmed by increased miR-9 gene expression in the miR-9 mimetic group and decreased miR-9 expression in the miR-9 inhibitor group relative to the miR mimetic control group (P < 0.05). Compared with the miR mimetic control group, the miR-9 mimetic group showed decreased cell proliferation and migration ability, and increased apoptosis, while in the miR-9 inhibitor group, cell proliferation and migration abilities were increased, and cell apoptosis decreased. Compared with the miR mimetic control group, the expression of Bcl-2 protein was decreased and the expression of Bax protein increased in the miR-9 mimetic group (P < 0.05), and the expression of Bcl-2 protein increased and expression of Bax protein decreased in the miR-9 inhibitor group (P < 0.05). Compared with the miR mimetic control group, the expression of matrix metalloproteinase 2 and matrix metalloproteinase-9 was decreased in the miR-9 mimetic group (P < 0.05), and the expression of matrix metalloproteinase 2 and matrix metalloproteinase-9 in the miR-9 inhibitor group was increased (P < 0.05). To conclude, miR-9 can inhibit the proliferation and migration of thyroid papillary cancer stem cells in vitro, but increase cell apoptosis. [ABSTRACT FROM AUTHOR]

Many fast renewing tissues are characterized by a hierarchical cellular architecture, with tissue specific stem cells at the root of the cellular hierarchy, differentiating into a whole range of specialized cells. There is increasing evidence that tumors are structured in a very similar way, mirroring the hierarchical structure of the host tissue. In some tissues, differentiated cells can also revert to the stem cell phenotype, which increases the risk that mutant cells lead to long lasting clones in the tissue. However, it is unclear under which circumstances de-differentiating cells will invade a tissue. To address this, we developed mathematical models to investigate how de-differentiation is selected as an adaptive mechanism in the context of cellular hierarchies. We derive thresholds for which de-differentiation is expected to emerge, and it is shown that the selection of de-differentiation is a result of the combination of the properties of cellular hierarchy and de-differentiation patterns. Our results suggest that de-differentiation is most likely to be favored provided stem cells having the largest effective self-renewal rate. Moreover, jumpwise de-differentiation provides a wider range of favorable conditions than stepwise de-differentiation. Finally, the effect of de-differentiation on the redistribution of self-renewal and differentiation probabilities also greatly influences the selection for de-differentiation. [ABSTRACT FROM AUTHOR]