CircRNA expression data from MCF-7, LCC2 and LCC9 cells
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE159980 | GEO | 2020/11/18
REPOSITORIES: GEO
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Project description:Acquired resistance to tamoxifen and fulvestrant is a challenging clinical problem in the treatment of hormone receptor-positive breast cancer patients. Non-coding RNAs (ncRNAs) could contribute to endocrine resistance but their specific roles in tamoxifen and fulvestrant resistance are not fully understood.
2020-11-18 | GSE159979 | GEO
Project description:Acquired resistance to tamoxifen and fulvestrant is a challenging clinical problem in the treatment of hormone receptor-positive breast cancer patients. Non-coding RNAs (ncRNAs) could contribute to endocrine resistance but their specific roles in tamoxifen and fulvestrant resistance are not fully understood.
2020-11-18 | GSE159968 | GEO
Project description:Endocrine therapy resistance remains a critical problem in the treatment of estrogen receptor alpha (ERα) breast cancer. Endocrine therapies target ERα via different modes of action. Drug resistance involves drug specific remodeling of the transcriptional and regulatory landscape. Using epigenomics and transcriptomics, we demonstrate that resistance to aromatase inhibitors (AI) induces phenotypical changes through epigenetic activation of cholesterol biosynthesis (CB) and keratin 80. Epigenetic activation is stable and involves both large topological domains and punctuated activation of single enhancers and super-enhancers. Specialized cancer cells expressing high levels of keratin 80 lead invasion through the extracellular matrix. Strikingly, we demonstrate that anti-cholesterol strategies can effectively arrest breast cancer invasion. Our work identifies a robust strategy to target resistant invasive breast cancer. All cell lines were grown in their respective media until they reached 70% confluency. Specifically, MCF7 were grown in DMEM+10% FBS and 1% Pen-Sprep-Glutamine. MCF7T as MCF7 with the addition of 100nM Tamoxifen. MCF7F as MCF7 with the addition of 100nM Fulvestrant. LTED were grown in DMEM without phenol + 10% DCS-FBS and1% Pen-Sprep-Glutamine. LTEDT as LTED with the addition of 100nM Tamoxifen. LTEDF as LTED with the addition of 100nM of Fulvestrant. All chemicals are purchased from Sigma. ChIP-seq was performed using Illumina methodology.
2015-12-31 | E-GEOD-60517 | biostudies-arrayexpress
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.
2009-08-27 | GSE14986 | GEO
Project description:Antiestrogen-responsive (#Wt), tamoxifen-(#TamR1/8) and fulvestrant-(#FulvR6/7) cells were routinely maintained in DMEM/F12 (phenolred-free) with 1% FCS, glutamine (2mM), penicillin/streptomycin (1%) and insulin (6ng/ml). Selection was done in 1µM tamoxifen or 100nM fulvestrant, respectively. For microarray studies, cells were in parallel cultured under steroid-depleted conditions: DMEM/F12 [1% charcoal-stripped, steroid-depleted FCS [CCS: (phenolred-free) with 1% FCS, glutamine (2mM), penicillin/streptomycin (1%) and insulin (6ng/ml)) for 3d and under steroid-depleted conditions treated for 1h with vehicle (DMSO), 4OHT (1µM) or fulvestrant (100nM), respectively.
2017-04-05 | E-MTAB-4426 | biostudies-arrayexpress
Project description:Purpose: Resistance to endocrine therapy in estrogen receptor-positive (ER+) breast cancer remains a major clinical problem. Recently, the CDK4/6 inhibitor palbociclib combined with letrozole was approved for treatment of ER+ advanced breast cancer, and other CDK4/6 inhibitors are being investigated in combination with different endocrine treatments. However, the role of CDK4/6 in endocrine resistance and their potential as predictive biomarkers of endocrine treatment response remains undefined. Experimental Design: We investigated the specific role of increased CDK6 expression in fulvestrant-resistant cells by gene knockdown and treatment with palbociclib, and evaluated the effect in cell proliferation, apoptosis and kinase activity. Furthermore, we evaluated CDK6 expression in metastatic samples from breast cancer patients treated or not with fulvestrant. Results: We found increased expression of CDK6 in two fulvestrant-resistant cell models vs. sensitive cells. Reduction of CDK6 expression impaired fulvestrant-resistant cell growth and induced apoptosis by reducing p70 ribosomal S6 kinase 2 activity. Treatment with palbociclib re-sensitized fulvestrant-resistant cells to fulvestrant through alteration of retinoblastoma phosphorylation. High CDK6 levels in metastatic samples from breast cancer patients treated with fulvestrant (N=45) correlated significantly with shorter progression-free survival (PFS) (p=0.0006), while no association was observed in patients receiving other endocrine treatments (N=41, p=0.874). Conclusions: Our results indicate that upregulation of CDK6 may be an important mechanism in overcoming fulvestrant-mediated growth inhibition in breast cancer cells. Patients with advanced ER+ breast cancer exhibiting high CDK6 expression in the metastatic lesions show shorter PFS upon fulvestrant treatment and thus may benefit from the addition of CDK4/6 inhibitors in their therapeutic regimens.
2017-02-08 | GSE74391 | GEO
Project description:Endocrine resistance in breast cancer is a major clinical problem with poorly understood mechanisms. Mass spectrometry-based proteomics of a clinically-relevant tamoxifen-resistant cell line model identified increased levels of minichromosome maintenance proteins (MCM), including MCM3, as central in cell cycle and DNA replication protein-protein interaction networks associated with tamoxifen resistance. Lowering MCM3 protein expression in tamoxifen-resistant cells restored tamoxifen sensitivity and altered phosphorylation of several cell cycle regulators, such as p53(Ser315, 33), CHK1(Ser317) and cdc25b(Ser323), suggesting that MCM3 activation of important cell cycle-associated proteins overcomes tamoxifen’s anti-proliferative effects. High MCM3 expression in primary tumor tissue from two independent cohorts of ER+ breast cancer patients receiving adjuvant tamoxifen mono-therapy was an independent prognostic marker significantly associated with a shorter recurrence-free survival.
2022-02-22 | PXD001087 | Pride
Project description:Oestrogen receptor alpha (ER, gene symbol ESR1) is the most important prognostic and treatment-predictive biomarker in breast cancer. Drugs targeting oestrogen and the ER for endocrine therapy of breast cancer include aromatase inhibitors, the selective ER modulator tamoxifen and the selective ER degrader fulvestrant. Tumours can develop resistance to endocrine therapy through several mechanisms, which is often linked to altered expression of the ER. To investigate the role of promoter methylation in regulation of ER expression, we used bisulfite sequencing to measure methylation at CpG sites in alternative ER promoter regions for six cell line models of fulvestrant resistance. Both CpG methylation and expression of alternative first exons changed dynamically with striking differences between cell lines that had stable or unstable resistance upon fulvestrant withdrawal. Methylation at some CpG sites was strongly negatively correlated with expression of specific first exons. In a breast tumour cohort, higher relative expression of upstream alternative first exons was associated with worse prognosis in post-menopausal women with ER-positive tumours who received endocrine therapy.
2024-08-06 | GSE251791 | GEO
Project description:To gain insight into the gene expression profile of breast patient derived organoids (PDOs) under endocrine therapy, and how cancer associated fibroblasts (CAFs) might influence gene expression and stimulate resistance, we performed RNA sequencing on three of the metastatic PDOs treated with control media and CAF-conditioned media, in the presence and absence of Fulvestrant (4-day treatment). These data revealed that Fulvestrant significantly suppressed the ER signature in the PDOs, suggesting that the ER-pathway is still active in these tumors although the patients had relapsed on ER-targeting agents (Tamoxifen, Letrozole).
2023-06-27 | GSE216540 | GEO
Project description:We aim to the investigate the role of tamoxifen in breast cancer progression. LCC2 and MCF-7 cells were used as the resistant and sensitive model.
2018-12-26 | GSE118774 | GEO