Project description:MCF-7:5C and MCF-7:2A are two in vitro models of Estrogen Receptor alpha positive (ER+) estrogen deprivation-resistant breast cancer. Both cell lines grow robustly in the absence of estrogen [PMID:1301400, PMID:7780972]. MCF-7:PF is an in vitro model of antihormone resistant breast cancer that exhibits the characteristics of acquired tamoxifen resistance [PMID:24183378] The goal of this study was to compare basal levels of gene expression during exponential phase of growth in MCF-7-derived models of endocrine resistance, relative to their isogenic parental cells
Project description:Resistance to endocrine therapy agents has presented a clinical obstacle in the treatment of hormone-dependent breast cancer. Our laboratory has initiated a study of microRNA regulation of signaling pathways that may result in breast cancer progression on aromatase inhibitors (AI). Microarray analysis of microRNA expression identified 115 significantly regulated microRNAs, of which 49 microRNAs were believed to be hormone-responsive. Within the AI-resistant cells, microRNAs were differentially expressed between the steroidal and non-steroidal AI-resistant lines. Also, a group of microRNAs were inversely expressed in the AI-resistant lines versus LTEDaro and tamoxifen-resistant. We focused our work on hsa-miR-128a which was hormone-responsive and up-regulated in the letrozole-resistant cell lines. Human miR-128a was shown to negatively target TGFBRI protein expression by binding to the 3âUTR region of the gene. Loss of TGFBRI resulted in compromised sensitivity to the growth inhibitory effects of TGFB in the letrozole-resistant lines. Inhibition of endogenous miR-128a resulted in re-sensitization of the letrozole-resistant lines to TGFB growth inhibitory effects. This data suggests that the hormone-responsive miR-128a can modulate TGFB signaling and survival of the letrozole-resistant cell lines. To our knowledge, this is the first study to address the role of microRNA regulation as well as TGFB signaling in AI-resistant breast cancer cell lines. We believe that in addition to estrogen-modulation of gene expression, hormone-regulated microRNAs may provide an additional level of post-transcriptional regulation of signaling pathways critically involved in breast cancer progression and AI-resistance. To look at microRNA expression profiles of breast cancer cell lines derived from MCF-7 cells that are resistant to endocrine therapy agents. MCF-7 cells that overexpress aromatase (MCF-7aro) were cultured long-term in the presence of endocrine therapy agents until cells acquired resistance. Three different aromatase inhibitors (letrozole, anastrozole or exemestane) were used, as well as the ER antagonist tamoxifen, or the hormone-free long-term estrogen deprived cells (LTED). Three replicates of the control cells (MCF-7aro) and all resistant cells were used for microarray experiments. Total of 23 samples were analyzed by microarray.
Project description:In order to help determine the genes involved in resistance of breast cancer to endocrine therapy, we compared global gene expression profiles of tamoxifen-resistant MCF-7 WT xenograft tumors with E2-supplemented tumors. Keywords: two group comparison
Project description:To explore the mechanism of endocrine resistance development in estrogen receptor positive breast cancer, transcriptome analysis of MCF-7 and its endocrine resistant derivatives, including tamoxifen resistant (TAMR) sub-lines and long-term estrogen deprivation (LTED) sub-lines, were performed using microarray.
Project description:Acquired resistance to endocrine therapy occurs with high frequency in patients with luminal breast cancer (LBC). We report here the establishment of four patient-derived xenograft models of LBC with acquired resistance in vivo to tamoxifen and estrogen deprivation. CEL files represent expresison data generated from 5 replicates (independent mice) of the following tumor models: HBCx22 (parental), HBCx22 TamR (tamoxifen-resistant), HBCx22 OvaR (ovariectomy-resistant), HBCx34 (parental), HBCx34 TamR (tamoxifen-resistant), HBCx34 OvaR (ovariectomy-resistant)
Project description:Advanced breast cancer is characterised by enhanced tumour adaptability to therapeutic pressure and the metastatic microenvironment. Transcriptome differences in three ER positive (ER+) cell models are uncovered through this RNA-seq analysis of MCF7 (endocrine sensitive), LY2 (endocrine resistant) and T347 (derived from an ER-positive, treatment resistant brain metastatic patient tumour) cells.
Project description:Emergence of antiestrogen-resistant cells in MCF-7 cells during suppression of estrogen signaling is a widely accepted model of acquired breast cancer resistance to endocrine therapy. To obtain insight into the genomic basis of endocrine therapy resistance, we characterized MCF-7 monoclonal sublines that survived 21-day exposure to tamoxifen (T-series sublines) or fulvestrant (F-series sublines) and sublines unselected by drugs (U-series). All T/F-sublines were resistant to the cytocidal effects of both tamoxifen and fulvestrant. However, their responses to the cytostatic effects of fulvestrant varied greatly, and their remarkably diversified morphology showed no correlation with drug resistance. mRNA expression profiles of the U-sublines differed significantly from those of the T/F-sublines, whose transcriptomal responsiveness to fulvestrant was largely lost. A set of genes strongly expressed in the U-sublines successfully predicted metastasis-free survival of breast cancer patients. Most T/F-sublines shared highly homogeneous genomic DNA aberration patterns that were distinct from those of the U-sublines. Genomic DNA of the U-sublines harbored many aberrations that were not found in the T/F-sublines. These results suggest that the T/F-sublines are derived from a common monoclonal progenitor that lost transcriptomal responsiveness to antiestrogens as a consequence of genetic abnormalities many population doublings ago, not from the antiestrogen-sensitive cells in the same culture during the exposure to antiestrogens. Thus, the apparent acquisition of antiestrogen resistance by MCF-7 cells reflects selection of preexisting drug-resistant subpopulations without involving changes in individual cells. Our results suggest the importance of clonal selection in endocrine therapy resistance of breast cancer.
Project description:Advanced breast cancer is characterised by enhanced tumour adaptability to therapeutic pressure and the metastatic microenvironment. Targeting epi-transcriptomic modulators may reverse cellular adaptability, offering new therapeutic strategies to treat metastatic disease. This study looks into the dynamic adaptations that occur in cancer cells in response to therapeutic pressure and metastatic evolution by profiling mRNA epi-transcriptomic modifications in models of disease progression. ER positive (ER+) cell models were used to represent progressive breast cancer, MCF7 (endocrine sensitive), LY2 (endocrine resistant) and T347 (derived from an ER-positive, treatment resistant brain metastatic patient tumour) cells. MeRIP sequencing was undertaken to determine genome-wide RNA methylated regions.