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MiR363-3p Mediates Maintenance and Chemoresistance of Breast Cancer Stem Cells

ABSTRACT: There is increasing evidence that cancer recurrence and resistance to chemotherapy are linked to a subset of cancer stem cells. However, detecting these cells specifically and targeting them therapeutically remain challenging. As microRNAs (miRNAs) are emerging as key players in cancer biology, we set up to identify miRNAs involved in chemoresistance of breast cancer stem cells. In this study, we enriched populations of chemoresistant cancer stem cells from breast cancer and non-transformed breast cell lines using mammospheres. These mammospheres were treated or not with two chemoreagents, and we profiled surviving cells using miRNA microarray analysis. Comparison of the profiles from treated and untreated mammospheres as well as control and cancer cells yielded a six-miRNAs signature specific for chemoresistant stem cell-enriched subpopulations. From this signature miR-363-3p was found to be most highly overexpressed in various breast cancer cell lines and derived cancer stem cell-enriched populations, whereas non-tumorigenic cells had low levels. Inhibition of miR-363-3p was found to decrease cancer stem cell maintenance and tumorigenicity in vitro. Consistently, miR-363-3p downregulation decreased tumor growth and metastatization by human tumor cells transplanted in mice. Finally, miR363-3p levels in the sera of 38 breast cancer patients enrolled in a neoadjuvant trial correlated well with the response to the chemotherapeutic treatments. Altogether, miR363-3p was identified as a mediator of the breast cancer stem cell phenotype, and it may provide a predictor of the response to chemotherapy from a simple blood test, as well as a potential therapeutic approach for cancer stem cell targeting. This data set aims at identifying differentially expressed miRNAs in chemoresistant mammospheres, by the profiling of miRNA in MCF7 breast cancer cell-derived mammospheres selected to be resistant to 5 Fluorouracil (5FU) or Paclitaxel, as compared to unselected MCF7 mammospheres.

ORGANISM(S): Homo sapiens

PROVIDER: GSE93710 | GEO | 2020/01/13

REPOSITORIES: GEO

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Project description:Tumorigenic breast cancer cells characterized by CD44 expression and low or undetectable CD24 levels (CD44+/CD24-/low) may be resistant to chemotherapy and therefore responsible for cancer relapse. Paired breast cancer core biopsies before and after neoadjuvant chemotherapy or lapatinib were obtained and as single cell suspensions stained using antibodies against CD24, CD44, and lineage markers, and then analyzed by flow cytometry. Mammosphere (MS) formation in culture was compared before and after treatment. Global gene expression differences between cancer cells bearing CD44+/CD24-/low cells and all other sorted cells, and between cancer MS and the primary bulk invasive cancers were analyzed. We report that CD44+/CD24-/low tumorigenic breast cancer cells were intrinsically chemoresistant - chemotherapy led to increased CD44+/CD24-/low cells, increased self-renewal capacity on MS assays, and enhanced tumorigeneicity in immunocompromised SCID/Beige mice. Conversely, in patients with HER2 overexpressing tumors, the EGFR/HER2 tyrosine kinase inhibitor, lapatinib decreased CD44+/CD24-/low cells, with the majority of these patients after conventional therapy achieving pathologic complete response, a validated surrogate marker for long-term survival. Gene transcription pathways that underlie chemoresistant, MS-forming CD44+/CD24-/low cells involve genes belonging to stem cell self-renewal, Wnt signaling, and early development pathways. Experiment Overall Design: Cells from human breast tumors were grown as mammospheres (MS). Experiment Overall Design: Isolated single cell suspensions from primary breast cancers were plated onto non-adherent (polyhema-coated) plastic, counted with a hematocytometer, and 20,000 cells were then seeded into a 6-well ultra-low attachment plate supplemented with 2mL MEGM, with the addition of 2 mL of freshly unfrozen MEGM every 3-4 days. Gene expression profiles were taken of both MS and primary bulk tumors and compared with each other.

Project description:The efficacy of cancer treatments have improved constantly in the last decade. However, therapeutic resistance and the lack of curative treatments in metastatic disease, raises the question if conventional anticancer therapies target the right cells. Indeed, these treatments might miss cancer stem cells (CSCs), which might also represent a more chemoresistant and radioresistant subpopulation within cancer. In this view using vaccines in tertiary prevention of cancer, i.e. residual disease treatment, might be particularly effective if vaccine-elicited immune response is directed against CSC oncoantigens (OAs) — proteins required for the neoplastic process — the chance that the tumour will evade the vaccine should be reduced. An important task to devise effective CSC preventive vaccines is therefore the identification of CSC OAs. We used gene-level transcription profiling of TuBo epithelial cell and three mammosphere passages (P1, P2 and P3). This analysis allowed the identification of two new breast cancer CSC OAs: TMPRSS4 and xCT. Both genes are linked to invasion, migration and metastasis. These results were achieved integrating data derived by the analysis of transcription profile of CSCs derived by BALB-neuT mouse breast cancer model with meta-analyses of seven large independent breast tumour data sets. TuBo cell line (E) was compared to passage 1 (P1), 2 (P2) and 3 (P3) mammospheres (three independent experiments for each experimental condition). Transcription profiling was done using MouseWG-6 v2.0 Illumina beadchips. After normalization and removal of non significant probes (i.e. those not expressed and those not changing) differential expression between epithelial and mammospheres, was assessed using regularized t-test comparing each mammosphere passage with respect to TuBo cells using a FDR ≤ 0.05 together with an |log2(fold-change)|≥1. The union of the three sets of differentially expressed transcripts produced a total of 495 transcripts.

Project description:Comparison af adherent growing breast cancer cell lines versus mammospheres under serum-free conditions Background: In patients with breast cancer, subsets of long-lived cells tolerate chemotherapies. These chemoresistant cells can remain dormant at secondary sites, such as bone and lung, for years and decades. Cancer cells endowed with drug resistance are maintained in vivo in a quiescent slow-growing state that preserves them from anti-proliferative cancer drugs. The mechanism of conversion from dormancy to growth remains poorly understood. We aimed to identify microRNAs (miRNAs) as master regulators of cancer stem cells (CSCs) maintainance, because one of the characteristics of CSCs is their slow proliferation or dormancy. MiRNA targeting CSCs may be an effective therapy to improve the prognosis of breast cancer patients. Methods: We performed miRNA array analysis to identify differences miRNA expression profiles between adherent cells and mammospheres that contain higher number of breast cancer stem cells (BCSCs). In this approach, we focused on expression of hsa-miR-27a. Further, roles of hsa-miR-27a target genes in maintaining BCSC properties were analysed . Results: Here, we showed that hsa-miR-27a was downregulated in mammosphere cells. The formation of BCSCs was attenuated by transfection of hsa-miR-27a. We found that hsa-miR-27a targets F-box and WD-40 domain protein 7 (FBW7), a tumor suppressor gene, thereby inducing tumor dormancy. Additionally, we found that hsa-miR-27a targets genes involved in GSH synthesis, including xCT (encoded by SLC7A11), a heterodimeric protein of a transporter subunit of the xC(-) system, cystathionine gamma-lyase (CTH/CSE), and nuclear factor-erythroid 2-related factor 2 (Nrf2/NFE2L2), thereby increasing intracellular reactive oxygen species (ROS) levels. Upregulation of these genes by antisense (as)-miR-27a induced autophagy. Conclusions: Previous studies showed that expression of hsa-miR-27a is elevated in breast cancer. Here, we showed that expression of hsa-miR-27a was reduced in BCSC. CSCs in the dormant state are resistant to chemotherapy due to inhibition of ROS accumulation in these cells. These results demonstrate that hsa-miR-27a plays an essential role in maintaining the BCSCs phenotype via regulation of FBW7, ROS related genes and the Nrf2 pathway, as well as in the dormant-to-proliferative switch of breast cancer cells. Thus, hsa-miR-27a represents a novel strategy for various type of breast cancer.

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MiR363-3p Mediates Maintenance and Chemoresistance of Breast Cancer Stem Cells

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