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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]

Immune checkpoint blockade therapy has been successful in treating some types of cancer but has not shown clinical benefits for treating leukaemia.sup.1. This result suggests that leukaemia uses unique mechanisms to evade this therapy. Certain immune inhibitory receptors that are expressed by normal immune cells are also present on leukaemia cells. Whether these receptors can initiate immune-related primary signalling in tumour cells remains unknown. Here we use mouse models and human cells to show that LILRB4, an immunoreceptor tyrosine-based inhibition motif-containing receptor and a marker of monocytic leukaemia, supports tumour cell infiltration into tissues and suppresses T cell activity via a signalling pathway that involves APOE, LILRB4, SHP-2, uPAR and ARG1 in acute myeloid leukaemia (AML) cells. Deletion of LILRB4 or the use of antibodies to block LILRB4 signalling impeded AML development. Thus, LILRB4 orchestrates tumour invasion pathways in monocytic leukaemia cells by creating an immunosuppressive microenvironment. LILRB4 represents a compelling target for the treatment of monocytic AML.The receptor LILRB4 on monocytic leukaemia cells suppresses T cell activity and support the infiltration of tumour cells into tissues., Author(s): Mi Deng [sup.1] , Xun Gui [sup.2] , Jaehyup Kim [sup.3] , Li Xie [sup.4] , Weina Chen [sup.3] , Zunling Li [sup.1] [sup.5] , Licai He [sup.1] [sup.6] [...]

Acute myeloid leukemia (AML) is a hematologic malignant disease largely affecting older adults with poor outcomes. Lack of effective targeted treatment is a major challenge in managing the disease in the clinic. Scaffolding adaptor Gab2 is amplified in a subset of AML. However, the causative role of Gab2 in AML remains to be explored. In this study, it was found that Gab2 was expressed at high levels in AML patient samples and AML cell lines. Experiments by knocking down Gab2 expression using shRNA showed that Gab2 promoted AML cell growth and migration in vitro and in vivo. Further studies using Gab2 mutants and pharmacological inhibitors revealed that Gab2 increased CREB phosphorylation via the SHP‐2/Erk signaling pathway. CREB phosphorylation contributed to Gab2‐induced cell migration by increasing MMP2 and MMP9 expression. This research indicates that high Gab2 expression promotes AML progression through the SHP2‐Erk‐CREB signaling pathway. CREB suppression may help treat AML with high Gab2 expression. [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]

Cholesterol is a risk factor for breast cancer. However, it is still unclear whether the cholesterol biosynthesis pathway plays any significant role in breast carcinogenesis. 24‐Dehydrocholesterol reductase (DHCR24) is a key enzyme in the cholesterol synthesis pathway. Although DHCR24 is reported to have different functions in different cancers, it is not clear whether DHCR24 is involved in breast cancer. In this study, we found that DHCR24 expression was higher in breast cancer especially in luminal and HER2 positive breast cancer tissues compared with normal breast. Changes in DHCR24 expression altered cellular cholesterol content without affecting the adherent growth of breast cancer cells. However, DHCR24 knockdown reduced whereas DHCR24 overexpression enhanced breast cancer stem‐like cell populations such as mammosphere and aldehyde dehydrogenase positive cell numbers. In addition, DHCR24 overexpression increased the expression of the Hedgehog pathway‐regulated genes. Treating DHCR24 overexpressing breast cancer cell lines with the Hedgehog pathway inhibitor GANT61 blocked DHCR24‐induced mammosphere growth and increased mRNA levels of the Hedgehog regulated genes. Furthermore, expression of a constitutively activated mutant of Smoothened, a key hedgehog signal transducer, rescued the decreases in mammosphere growth and Hedgehog regulated gene expression induced by knockdown of DHCR24. These results indicate that DHCR24 promotes the growth of breast cancer stem‐like cells in part through enhancing the Hedgehog signaling pathway. Our data suggest that cholesterol contribute to breast carcinogenesis by enhancing Hedgehog signaling and cancer stem‐like cell populations. Enzymes including DHCR24 involved in cholesterol biosynthesis should be considered as potential treatment targets for breast cancer. [ABSTRACT FROM AUTHOR]

As a subtype of acute myeloid leukemia (AML), acute promyelocytic leukemia (APL) is characterized by a chromosomal translocation, most of which result in the production of a PML‐RAR alpha fusion protein. Although the overall survival rate of APL patients has improved dramatically due to all‐trans retinoic acid (ATRA) treatment, ATRA‐resistance remains a clinical challenge in the management of APL. Therefore, alternative agents should be considered for ATRA‐resistant APL patients. Here, we report that antimalaria drug primaquine phosphate (PRQ) exhibits an anti‐leukemia effect on both ATRA‐sensitive cell line NB4 and ATRA‐resistant APL cell lines, NB4‐LR2, NB4‐LR1, and NB4‐MR2. Moreover, PRQ significantly inhibited primary colony formation of untreated or relapsed APL patients. Further study showed that PRQ could induce the apoptosis of APL cells by inhibiting NF‐κB signaling pathway. The in vivo study showed that PRQ significantly inhibited NB4‐LR2 xenograft tumors growth. These results suggest that PRQ is a potential therapeutic agent for ATRA‐resistant APL patients. [ABSTRACT FROM AUTHOR]

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]

IK4 is an isoform of IKAROS gene which plays a key role in the hematopoiesis, in this work, the construction of retro-virus vector of IK4 mutation and its expression in leukemic cells was investigated. PCR site-directed mutagenesis method based on overlap extension was used to construct four IK4 gene mutants of single- or multi-site mutations, which were then cloned into the retrovirus vector Pmscv-puro to form recombinant expression vector. The point mutations were verified by DNA sequencing. The recombinant expression vectors were co-transfected with packaging plasmids VSVG and Gag-Pol into 293T cells to produce retroviruses. Supernatants containing retroviruses were collected and were used to infect NB4 cells. Puromycin was used to select stable cell lines. The expression of mutants was verified by Western blotting analysis. Four IK4 gene mutants of single- or multi-site mutations were successfully constructed by overlap extension PCR, and the mutants were expressed in leukemic cells, which will provide basis for subsequent function and mechanism research. [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]

Mucin 1 (MUC1) has been regarded as an ideal target for cancer treatment, since it is overexpressed in a variety of different cancers including the majority of breast cancer. However, there are still no approved monoclonal antibody drugs targeting MUC1. In this study, we generated a humanized MUC1 (HzMUC1) antibody from our previously developed MUC1 mouse monoclonal antibody that only recognizes MUC1 on the surface of tumor cells. Furthermore, an antibody-drug conjugate (ADC) was generated by conjugating HzMUC1 with monomethyl auristatin (MMAE), and the efficacy of HzMUC1-MMAE on the MUC1-positive HER2+ breast cancer in vitro and in 'Xenograft' model was tested. Results from western blot analysis and immunoprecipitation revealed that the HzMUC1 antibody did not recognize cell-free MUC1-N in sera from breast cancer patients. Confocal microscopy analysis showed that HzMUC1 antibody bound to MUC1 on the surface of breast cancer cells. Results from mapping experiments suggested that HzMUC1 may recognize an epitope present in the interaction region between MUC1-N and MUC1-C. Results from colony formation assay and flow cytometry demonstrated that HzMUC1-MMAE significantly inhibited cell growth by inducing G2/M cell cycle arrest and apoptosis in trastuzumab-resistant HER2-positive breast cancer cells. Meanwhile, HzMUC1-MMAE significantly reduced the growth of HCC1954 xenograft tumors by inhibiting cell proliferation and enhancing cell death. In conclusion, our results indicate that HzMUC1-ADC is a novel therapeutic drug that can overcome trastuzumab resistance of breast cancer. HzMUC1-ADC should also be an effective therapeutic drug for the treatment of different MUC1-positive cancers in clinic., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Therapeutic strategies are urgently needed for patients with acute myeloid leukemia (AML). Leukocyte immunoglobulin-like receptor B4 (LILRB4), which suppresses T-cell activation and supports tissue infiltration of AML cells, represents an attractive drug target for anti-AML therapeutics. Here, we report the identification and development of an LILRB4-specific humanized mAb that blocks LILRB4 activation. This mAb, h128-3, showed potent activity in blocking the development of monocytic AML in various models including patient-derived xenograft mice and syngeneic immunocompetent AML mice. MAb h128-3 enhanced the anti-AML efficacy of chemotherapy treatment by stimulating mobilization of leukemia cells. Mechanistic studies revealed four concordant modes of action for the anti-AML activity of h128-3: (i) reversal of T-cell suppression, (ii) inhibition of monocytic AML cell tissue infiltration, (iii) antibody-dependent cellular cytotoxicity, and (iv) antibody-dependent cellular phagocytosis. Therefore, targeting LILRB4 with antibody represents an effective therapeutic strategy for treating monocytic AML., (©2019 American Association for Cancer Research.)

Androgen receptor (AR) is widely expressed in different subtypes of breast cancer (BC). However, it is unclear how AR functions in HER2 positive (+) BC. Knockdown of AR with shRNAs and a new generation anti-androgen drug, Enzalutamide, were used to explore the involvement of AR on the growth of HER2 + BC cells (HCC1954 and SKBR3). AR shRNA or Enzalutamide inhibited the growth of SKBR3 cells at a similar extend compared to trastuzumab, an approved HER2 targeted drug. Combining Enzalutamide with trastuzumab further decreased the growth of HCC1954 and SKBR3 cells compared with single agent alone in vitro. Biochemical analysis revealed that inhibiting AR resulted in decreased HER2 phosphorylation and activation of Erk and Akt, without affecting the HER2 and HER3 expression. The in vivo efficacy of Enzalutamide was further tested using the HCC1954 xenograft model. Enzalutamide impaired the growth of HCC1954 tumor at a level comparable to that by trastuzumab. Enzalutamide decreased Ki67 staining and increased activated caspase3 staining compared with vehicle control in HCC1954 tumors. Our results indicate AR plays an important role in promoting the growth of HER2 + BC by cross-talking with the HER2 signaling. AR drug may be used as an alternative second line therapy for treating HER2 + BC.

Ikaros is an important transcription factor involved in the development and differentiation of hematopoietic cells. However, its role in the treatment of hematopoietic malignancies such as leukemia is less well understood. In the present study, it was observed by data mining of the Oncomine database that high expression levels of full-length Ikaros (IK1) is correlated with increased sensitivity of cancer cells to treatments with chemotherapeutic drugs, including doxorubicin (DOX). To examine the functional significance of this observation, the expression of IK1 in a leukemia cell line was altered, and the response of leukemic cells to DOX treatment was analyzed. It was observed that overexpression of IK1 could enhance DOX-induced apoptosis, while knockdown of IK1 attenuated DOX-induced apoptosis in leukemic cells. Further experiments demonstrated that IK1 sensitized leukemic cells to DOX-induced apoptosis, probably through upregulation of caspase-9. These data suggest that high expression levels of IK1 may be a potential biomarker to predict responses of leukemia patients to treatment with chemotherapy.