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Expression of miR-200c in claudin-low breast cancer alters stem cell functionality, enhances chemosensitivity and reduces metastatic potential

ABSTRACT: Claudin-low tumors are a highly aggressive breast cancer subtype with no targeted treatments and a clinically documented resistance to chemotherapy. They are significantly enriched in cancer stem cells (CSCs), which makes claudin-low tumor models particularly attractive for studying CSC behavior and developing novel approaches to minimize CSC therapy resistance. One proposed mechanism by which CSCs arise is via an epithelial-mesenchymal transition (EMT), and reversal of this process may provide a potential therapeutic approach for increasing tumor chemosensitivity. Therefore, we investigated the role of the miR-200 family of microRNAs in regulating the epithelial state, stem-like properties, and therapeutic response in an in vivo primary, syngeneic p53null claudin-low tumor model that is normally deficient in miR-200 expression. Using an inducible lentiviral approach, we expressed the miR-200c cluster in this claudin-low model and found that it changed the epithelial state, and consequently, impeded CSC behavior in these mesenchymal tumors. Moreover, these state changes were accompanied by a decrease in proliferation and an increase in the differentiation status. MiR-200c expression also forced a significant reorganization of tumor architecture, affecting important cellular processes involved in cell-cell contact, cell adhesion, and motility. Accordingly, induced miR200c expression also significantly enhanced the chemosensitivity and decreased the metastatic potential of this p53null claudin-low tumor model. Collectively, our data suggest that miR-200c expression in claudin-low tumors offers a potential therapeutic application to disrupt the EMT program on multiple fronts in this mesenchymal tumor subtype, by altering tumor growth, chemosensitivity, and metastatic potential in vivo.

ORGANISM(S): Mus musculus

PROVIDER: GSE62230 | GEO | 2015/06/22

SECONDARY ACCESSION(S): PRJNA263589

REPOSITORIES: GEO

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Project description:A large body of evidence has demonstrated that many human tumors are maintained by a small cell population called cancer stem cells (CSCs) or tumor progenitors, which are responsible for tumor formation, therapy resistance and metastasis. We found that ionizing radiation treatment enriches for the CSC phenotype and properties by preferential survival and expansion of tumor progenitor cells. Our studies revealed that aldehyde dehydrogenase (ALDH) activity is indicative of prostate tumor progenitor cells with increased chemo- and radioresistance, enhanced migratory potential, improved DNA- double strand break repair and activation of the signaling pathways, which promote self-renewal and epithelial-mesenchymal transition. We found that X-ray irradiation can convert the bulk tumor cells to more clonogenic and radioresistant population positive for expression of CSC markers. For the first time we showed that irradiation increases histone H3K4 and H3K36 methylation in prostate cancer cells, thereby reactivating transcription of epigenetically silenced target genes. We showed that radioresistant tumor progenitor population undergoes a phenotypical switching during the course of irradiation, suggesting that controlling the phenotypical and functional properties of CSCs during radiation therapy is ultimative for the optimization of treatment strategies. Our studies have shown that CSC markers may be beneficial in prediction of tumor radiocurability, and combination of irradiation with therapies directed against CSCs can be a useful strategy to improve cancer treatment. To identify potential biomarkers associated with CSC population in these xenograft tumors, we performed whole genome gene expression profiling of the xenograft tumors treated with NVP-BEZ235, which eliminates prostate cancer progenitor populations or with Taxotere, which targets the bulk tumor cells as compared with vehicle-treated control mice. Treatment with either vehicle, Taxotere, NVP-BEZ235, or a combination of these two. There are no replicates

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Expression of miR-200c in claudin-low breast cancer alters stem cell functionality, enhances chemosensitivity and reduces metastatic potential

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