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Acute myeloid leukemia (AML) is one of the most common types of acute leukemia in adults with the lowest survival rate of all leukemia. Resistance to cytarabine and anthracycline-based chemotherapy is a major cause of treatment failure. Thus, finding new drugs with anti-leukemia activities and minimal side effect is urgently needed. Here through screening more than 1000 drugs approved by the Food and Drug Administration (FDA) of United States, the anthelmintic drug mebendazole (MBZ) was found to inhibit the growth of AML cell lines (THP-1, U937, NB4 and K562) and bone marrow mononuclear cells (BM-MNCs) from AML patients at pharmacologically achievable concentrations. In contrast, similar concentration of MBZ had little inhibitory effect on the growth of normal peripheral blood mononuclear cells (PBMC) or human umbilical vein endothelial cells (HUVEC). In addition, MBZ induced mitotic arrest and mitotic catastrophe in AML cells based on nuclear morphology, cell cycle distribution, mitotic marker analyses and the number of multinucleated cells and apoptotic cells. Furthermore, MBZ treatment inhibited activation of Akt and Erk in AML leukemic cells. Finally, MBZ repressed the progression of leukemic cells in vivo and prolonged survival in AML xenograft mouse model. Taken together, our results suggest that MBZ could be a potential new therapeutic agent for the treatment of AML patients. [ABSTRACT FROM AUTHOR]

Besides its well-known function in allergic response, mast cell, one of the key immune cells present in tumor microenvironment, plays important roles in cancer progression. However, the functional role of mast cells in breast cancer development and metastasis is not well understood. To test the involvement of mast cells in breast cancer, we examined the effects of loss of mast cells on mammary tumor development by crossing the well-known mast cell deficient mouse strain sash (KitW-sh/W-sh) with the mammary tumor transgenic mouse strain MMTV-Polyoma Middle T antigen (Py MT). Although mammary tumor onset was not affected in the absence of mast cells, mammary growth and metastasis were reduced in Py MT/KitW-sh/W-sh mice compared with Py MT/wild-type mice ( WT). Histological and immunofluorescent analyses showed that tumors from Py MT/KitW-sh/W-sh mice showed largely differentiated morphology with reduced angiogenesis compared with MMTV-Py MT/ WT mice. Our results suggest that mast cells may promote breast cancer growth and metastasis. Agents that can block mast cells growth are potential new therapies to treat metastatic breast cancer. [ABSTRACT FROM AUTHOR]

Therapy-related leukemia carries a poor prognosis, and leukemia after chemotherapy is a growing risk in clinic, whose mechanism is still not well understood. Ikaros transcription factor is an important regulator in hematopoietic cells development and differentiation. In the absence of Ikaros, lymphoid cell differentiation is blocked at an extremely early stage, and myeloid cell differentiation is also significantly affected. In this work, we showed that chemotherapeutic drug etoposide reduced the protein levels of several isoforms of Ikaros including IK1, IK2 and IK4, but not IK6 or IK7, by accelerating protein degradation, in leukemic cells. To investigate the molecular mechanism of Ikaros degradation induced by etoposide, immunoprecipitation coupled with LC-MS/MS analysis was conducted to identify changes in protein interaction with Ikaros before and after etoposide treatment, which uncovered KCTD5 protein. Our further study demonstrates that KCTD5 is the key stabilizing factor of Ikaros and chemotherapeutic drug etoposide induces Ikaros protein degradation through decreasing the interaction of Ikaros with KCTD5. These results suggest that etoposide may induce leukemic transformation by downregulating Ikaros via KCTD5, and our work may provide insights to attenuate the negative impact of chemotherapy on hematopoiesis. [ABSTRACT FROM AUTHOR]

Background: Breast cancer is the leading cause of cancer death for women worldwide. Most of the breast cancer death are due to disease recurrence and metastasis. Increasingly accumulating evidence indicates that mitochondria play key roles in cancer progression and metastasis. Our recent study revealed that transmembrane protein PRRG4 promotes the metastasis of breast cancer. However, it is not clear whether PRRG4 can affect the migration and invasion of breast cancer cells through regulating mitochondria function. Methods: RNA-seq analyses were performed on breast cancer cells expressing control and PRRG4 shRNAs. Quantitative PCR analysis and measurements of mitochondrial ATP content and oxygen consumption were carried out to explore the roles of PRRG4 in regulating mitochondrial function. Luciferase reporter plasmids containing different lengths of promoter fragments were constructed. Luciferase activities in breast cancer cells transiently transfected with these reporter plasmids were analyzed to examine the effects of PRRG4 overexpression on promoter activity. Transwell assays were performed to determine the effects of PRRG4-regulated pathway on migratory behaviors of breast cancer cells. Results: Analysis of the RNA-seq data revealed that PRRG4 knockdown decreased the transcript levels of all the mitochondrial protein-encoding genes. Subsequently, studies with PRRG4 knockdown and overexpression showed that PRRG4 expression increased mitochondrial DNA (mtDNA) content. Mechanistically, PRRG4 via Src activated STAT3 in breast cancer cells. Activated STAT3 in turn promoted the transcription of mtDNA polymerase POLG through a STAT3 DNA binding site present in the POLG promoter region, and increased mtDNA content as well as mitochondrial ATP production and oxygen consumption. In addition, PRRG4-mediated activation of STAT3 also enhanced filopodia formation, migration, and invasion of breast cancer cells. Moreover, PRRG4 elevated migratory behaviors and mitochondrial function of breast cancer cells through POLG. Conclusion: Our results indicate that PRRG4 via the Src-STAT3-POLG axis enhances mitochondrial function and promotes migratory behaviors of breast cancer cells. [ABSTRACT FROM AUTHOR]

Background: Pancreatic cancer is one of the most aggressive malignancies without effective targeted therapies. MUC1 has emerged as a potential common target for cancer therapy because it is overexpressed in a variety of different cancers including the majority of pancreatic cancer. However, there are still no approved monoclonal antibody drugs targeting MUC1 have been reported. Recently, we generated a humanized MUC1 antibody (HzMUC1) specific to the interaction region between MUC1-N and MUC1-C. In this study, we generated the antibody drug conjugate (ADC) by conjugating HzMUC1 with monomethyl auristatin (MMAE), and examined the efficacy of HzMUC1-MMAE against the MUC1-positive pancreatic cancer in vitro and in vivo. Methods: Western blot and immunoprecipitation were used to detect MUC1 in pancreatic cancer cells. MUC1 localization in pancreatic cancer cells was determined by confocal microscopy. HzMUC1 was conjugated with the monomethyl auristatin (MMAE), generating the HzMUC1-MMAE ADC. Colony formation assay and flow cytometry were used to assess the effects of the HzMUC1-MMAE cell viability, cell cycle progression and apoptosis. Capan-2 and CFPAC-1 xenograft model were used to test the efficacy of HzMUC1-MMAE against pancreatic cancer. Results: HzMUC1 antibody binds to MUC1 on the cell surface of pancreatic cancer cells. HzMUC1-MMAE significantly inhibited cell growth by inducing G2/M cell cycle arrest and apoptosis in pancreatic cancer cells. Importantly, HzMUC1-MMAE significantly reduced the growth of pancreatic xenograft tumors by inhibiting cell proliferation and enhancing cell death. Conclusion: Our results indicate that HzMUC1-ADC is a promising novel targeted therapy for pancreatic cancer. HzMUC1-ADC should also be an effective drug for the treatment of different MUC1-positive cancers. [ABSTRACT FROM AUTHOR]

Background: Pancreatic cancer is one of the most aggressive malignancies without effective targeted therapies. MUC1 has emerged as a potential common target for cancer therapy because it is overexpressed in a variety of different cancers including the majority of pancreatic cancer. However, there are still no approved monoclonal antibody drugs targeting MUC1 have been reported. Recently, we generated a humanized MUC1 antibody (HzMUC1) specific to the interaction region between MUC1-N and MUC1-C. In this study, we generated the antibody drug conjugate (ADC) by conjugating HzMUC1 with monomethyl auristatin (MMAE), and examined the efficacy of HzMUC1-MMAE against the MUC1-positive pancreatic cancer in vitro and in vivo. Methods: Western blot and immunoprecipitation were used to detect MUC1 in pancreatic cancer cells. MUC1 localization in pancreatic cancer cells was determined by confocal microscopy. HzMUC1 was conjugated with the monomethyl auristatin (MMAE), generating the HzMUC1-MMAE ADC. Colony formation assay and flow cytometry were used to assess the effects of the HzMUC1-MMAE cell viability, cell cycle progression and apoptosis. Capan-2 and CFPAC-1 xenograft model were used to test the efficacy of HzMUC1-MMAE against pancreatic cancer. Results: HzMUC1 antibody binds to MUC1 on the cell surface of pancreatic cancer cells. HzMUC1-MMAE significantly inhibited cell growth by inducing G2/M cell cycle arrest and apoptosis in pancreatic cancer cells. Importantly, HzMUC1-MMAE significantly reduced the growth of pancreatic xenograft tumors by inhibiting cell proliferation and enhancing cell death. Conclusion: Our results indicate that HzMUC1-ADC is a promising novel targeted therapy for pancreatic cancer. HzMUC1-ADC should also be an effective drug for the treatment of different MUC1-positive cancers. [ABSTRACT FROM AUTHOR]

Background. Cytogenetic abnormalities are considered initiating events in the pathogenesis of multiple myeloma (MM) and are assumed to be of clinical significance. Methods. Fluorescence in situ hybridization (FISH) was used to analyze chromosomal architecture in 101 patients with MM. We evaluated overall patient survival and assessed the cytotoxicity of imatinib against MM cells using a CCK8 assay. Results. ABL gene amplification was detected in 67 patients (66.3%). However, ABL gene amplification was not associated with clinical features, cytogenetic abnormalities (c-Myc amplification, IGH rearrangement, RB1 deletion, p53 deletion, or 1q21 amplification), or overall survival. ABL amplification in MM cell lines (LP-1 and U266) was revealed by FISH. Furthermore, the ABL protein was easily detectable in MM cell lines and some tumor cells by western blotting. A CCK8 assay indicated limited cytotoxicity of imatinib against MM cells. Conclusions. Our study firstly discussed ABL gene amplification was prevalent in MM cells, and we believe that the ABL gene would potentially be a useful target in the treatment of combination strategy for MM with ABL amplification in the future. [ABSTRACT FROM AUTHOR]

SH2-domain containing protein tyrosine phosphatase 1 (Shp1/PTPN6) is mainly expressed in hematopoietic cells and acts a negative signaling regulator. Although Shp1 is also expressed in epithelial cells, the function of shp1 in normal epithelial is still less well understood, especially in regulating the growth of epithelial cells. In this study, different shRNAs and siRNAs against Shp1 were used to knockdown Shp1 expression in MCF10A, an immortalized mammary epithelial cell line. Shp1 knockdown resulted in inhibited cell growth in part due to lower percentage of MCF10A cells entering into S phase and reduced cyclin D1 expression. Accordingly, EGF-induced tyrosyl phosphorylation of EGFR and Stat5 was significantly inhibited in cells with Shp1 knockdown compared with control whereas EGF-induced Akt and Erk phosphorylation was not affected by Shp1 knockdown. Further analysis revealed that Shp1 knockdown lead to decreased EGFR protein expression without affecting EGFR mRNA expression or increasing EGFR protein degradation. Our data indicate that Shp1 functions as a positive regulator and acts in a novel mechanism through promoting EGFR protein expression in mammary epithelial cells. [ABSTRACT FROM AUTHOR]

Scaffolding adaptor Gab2 is overexpressed in a subset of high-grade ovarian cancer. Our published work shows that Gab2 via PI3K enhances migratory behaviors and epithelial to mesenchymal transition (EMT) features of ovarian cancer cells in vitro. However, it is still unclear how Gab2/PI3K pathway reuglates EMT characteristics and whether Gab2 promotes the growth of ovarian cancer stem cell (CSC)-like population and metastatic growth. In this study, we examined the effects of Gab2 expression on CSC-like cell growth using Aldefluor and tumorshpere assays commonly used for assessing ovarian cancer cells with CSC properties. Gab2 overexpression increased the number of ALDH+ cells and tumorsphere formation in two different ovarian cancer cell lines OVCAR5 and OVCAR8, whereas knockdown of Gab2 decreased the number of ALDH+ cells and tumorsphere formation in Caov-3 cells. Furthermore, Gab2 promoted metastatic tumor growth of OVCAR5 in nude mice. Mechanistically, we uncovered that Gab2 via PI3K specifically inhibited miR-200c expression. miR-200c downregulation contributed to the Gab2-enhanced cell migratory behaviors, EMT properties, and the expansion of ALDH+ cells and tumorspheres. Furthermore, Gab2 promoted CD44 expression and cell migration/invasion through miR-200c downregulation. Our findings support a model that Gab2-PI3K pathway via miR-200c downregulation promotes CD44 expression, EMT characteristics, and CSC-like cell growth. Therapies involving miR-200c or targeting CD44 should help treat ovarian cancer with high Gab2 expression. • Gab2 promotes the growth of CSC-like population of ovarian cancer cells. • Gab2 promotes metastatic growth of ovarian cancer cells in xenograft. • Gab2 via PI3K inhibits miR-200c expression in ovarian cancer cells. • Gab2 via miR-200c downregulation promotes phenotypes of EMT and CSC. • Gab2 inhibition of miR-200c enhances CD44 expression and cell migration/invasion. [ABSTRACT FROM AUTHOR]

Background: Acute myeloid leukemia (AML) is a heterogeneous group of hematopoietic malignancies due to sophisticated genetic mutations and epigenetic dysregulation. MicroRNAs (miRNAs), a class of small non-coding RNAs, are important regulators of gene expression in all biological processes, including leukemogenesis. Recently, miR-375 has been reported to be a suppressive miRNA in multiple types of cancers, but its underlying anti-leukemia activity in AML is largely unknown.Methods: Quantitative reverse transcriptase PCR (qRT-PCR) was used to measure the expression of miR-375 and HOXB3 in leukemic cells and normal controls. Targets of miR-375 were confirmed by western blot and luciferase assay. Phenotypic effects of miR-375 overexpression and HOXB3 knockdown were assessed using viability (trypan blue exclusion assay), colony formation/replating, as well as tumor xenograft assays in vivo.Results: The expression of miR-375 was substantially decreased in leukemic cell lines and primary AML blasts compared with normal controls, because DNA hypermethylation of precursor-miR-375 (pre-miR-375) promoter was discovered in leukemic cells but not in normal controls. Lower expression of miR-375 predicted poor outcome in AML patients. Furthermore, forced expression of miR-375 not only decreased proliferation and colony formation in leukemic cells but also reduced xenograft tumor size and prolonged the survival time in a leukemia xenograft mouse model. Mechanistically, overexpression of miR-375 reduced HOXB3 expression and repressed the activity of a luciferase reporter through binding 3'-untranslated regions (3'-UTR) of HOXB3 mRNA. Overexpression of HOXB3 partially blocked miR-375-induced arrest of proliferation and reduction of colony number, suggesting that HOXB3 plays an important role in miR-375-induced anti-leukemia activity. Knockdown of HOXB3 by short hairpin RNAs reduced the expression of cell division cycle associated 3 (CDCA3), which decreased cell proliferation. Furthermore, HOXB3 induced DNA methyltransferase 3B (DNMT3B) expression to bind in the pre-miR-375 promoter and enhanced DNA hypermethylation of pre-miR-375, leading to the lower expression of miR-375.Conclusions: Collectively, we have identified a miR-375-HOXB3-CDCA3/DNMT3B regulatory circuitry which contributes to leukemogenesis and suggests a therapeutic strategy of restoring miR-375 expression in AML. [ABSTRACT FROM AUTHOR]