Differential expression profiling of the TamR cells following AR knockdown
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE115270 | GEO | 2018/06/05
REPOSITORIES: GEO
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Project description:To elucidate the molecular mechanisms of tamoxifen resistance in breast cancer, we performed gene array analysis and identified 366 genes with altered expression in four unique tamoxifen resistant (TamR) cell lines vs the parental tamoxifen sensitive MCF7/S0.5 cell line. Most of these genes were funcationally linked to cell proliferation, death and control gene expression, and include FYN, PRKCA, ITPR1, DPYD, DACH1, LYN, GBP1 and PRLR. Treatment with FYN specific small interfering RNA or a SRC family kinase inhibitor reduced cell growth of TamR cell lines while exerting no significant effect on MCF7/S0.5 cells. Moreover, overexpression of FYN in parental tamoxifen-sensitive MCF7/S0.5 cells resulted in reduced sensitivity to tamoxifen, demonstrating growth and survival promoting function of FYN in MCF7 cells. FYN knockdown in TamR cells led to reduced phosphorylation of 14-3-3 and CDc 25A, suggesting that FYN, by activation of of important cell cycle-associated proteins, may overcome the anti-proliferative effects of tamoxifen. Evaluation of the subcellular localization of FYN in primary breast tumors from two cohorts of endocrine-treated ER+ breast cancer patients, one with advanced disease (N = 47) and the other with early disease (N = 76), showed that in the former, plasma membrane-associated FYN expression strongly correlated with longer progression-free survival (P<0.0002). Similarly, in early breast cancer patients, membrane-associated expression of FYN in the primary breast tumor was significantly associated with increased metastasis-free (P<0.04) and overall (P<0.004) survival independent of tumor size, grade or lymph node status. Our results indicate that FYN has an important role in tamoxifen resistance, and its subcellular localization in breast tumor cells may be an important novel biomarker of response to endocrine therapy in breast cancer.
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Project description:Tamoxifen is an effective anti-estrogen treatment for patients with estrogen receptor-positive (ER+) breast cancer. However, about 30% of such patients receiving tamoxifen as an adjuvant therapy experience recurrence within 15 years, and most patients with advanced disease eventually develop resistance to tamoxifen. To elucidate the underlying molecular mechanisms of tamoxifen resistance, we performed a systematic analysis of miRNA-mediated gene regulation in three clinically-relevant tamoxifen-resistant human breast cancer cell lines (TamRs) compared to their parental tamoxifen-sensitive MCF-7/S0.5 cell line. Alterations in the expression of 131 miRNAs in tamoxifen-resistant vs. parental cell lines were identified, 22 of which were common to all TamRs using both sequencing and LNA-based quantitative PCR technologies. ER+ and tamoxifen sensitive breast cancer cell line (MCF-7/S0.5) and its derived tamoxifen resistant clones: TAMR-1, TAMR-4 and TAMR-8 were miRNA expression profiled in triplicates of each using Exiqon's miRCURY LNA based microRNA Ready-to-use PCR, Human panel I+II, V2.R (Exiqon, product number 203608).
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