scholarly journals Roles for miRNAs in endocrine resistance in breast cancer

2015 ◽  
Vol 22 (5) ◽  
pp. R279-R300 ◽  
Author(s):  
Penn Muluhngwi ◽  
Carolyn M Klinge
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Aromatase Inhibitors ◽  
Estrogen Receptor Alpha ◽  
Acquired Resistance ◽  
Endocrine Resistance ◽  
Breast Cancer Patients ◽  
Initial Tumor ◽  
Bona Fide

Therapies targeting estrogen receptor alpha (ERα), including selective ER modulators such as tamoxifen, selective ER downregulators such as fulvestrant (ICI 182 780), and aromatase inhibitors such as letrozole, are successfully used in treating breast cancer patients whose initial tumor expresses ERα. Unfortunately, the effectiveness of endocrine therapies is limited by acquired resistance. The role of microRNAs (miRNAs) in the progression of endocrine-resistant breast cancer is of keen interest in developing biomarkers and therapies to counter metastatic disease. This review focuses on miRNAs implicated as disruptors of antiestrogen therapies, theirbona fidegene targets and associated pathways promoting endocrine resistance.

scholarly journals Identification and Analysis of Estrogen Receptor α Promoting Tamoxifen Resistance-Related lncRNAs

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Xiulei Zhang ◽  
Shanjun Gao ◽  
Zhen Li ◽  
Wei Wang ◽  
Guangzhi Liu
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Cancer Patients ◽  
Estrogen Receptor Alpha ◽  
Acquired Resistance ◽  
Tamoxifen Resistance ◽  
Estrogen Receptor Α ◽  
Rna Seq ◽  
Breast Cancer Patients ◽  
Mcf 7

70-75% breast cancer patients are estrogen receptor alpha positive (ERα+), and the antiestrogen drug tamoxifen has been used for the past three decades. However, in 20-30% of these patients, tamoxifen therapy fails due to intrinsic or acquired resistance. A previous study has showed ERα signaling still exerts significant roles in the development of tamoxifen resistance and several lncRNAs have been demonstrated important roles in tamoxifen resistance. But ERα directly regulated and tamoxifen resistance related lncRNAs remain to be discovered. We reanalyze the published ERα chromatin immunoprecipitation-seq (ChIP-seq) and RNA-seq data of tamoxifen-sensitive (MCF-7/WT) and tamoxifen-resistant (MCF-7/TamR) breast cancer cells. We demonstrate that there are differential ERα recruitment events and the differentials may alert the expression profile in MCF-7/WT and MCF-7/TamR cells. Furthermore, we make an overlap of the ERα binding lncRNAs and differentially expressed lncRNAs and get 49 ERα positively regulated lncRNAs. Among these lncRNAs, the expression levels of AC117383.1, AC144450.1, RP11-15H20.6, and ATXN1-AS1 are negatively correlated with the survival probability of breast cancer patients and ELOVL2-AS1, PCOLCE-AS1, ITGA9-AS1, and FLNB-AS1 are positively correlated. These lncRNAs may be potential diagnosis or prognosis markers of tamoxifen resistance.

scholarly journals The SERM/SERD bazedoxifene disrupts ESR1 helix 12 to overcome acquired hormone resistance in breast cancer cells

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Sean W Fanning ◽  
Rinath Jeselsohn ◽  
Venkatasubramanian Dharmarajan ◽  
Christopher G Mayne ◽  
Mostafa Karimi ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Estrogen Receptor Alpha ◽  
Hormone Replacement ◽  
Acquired Resistance ◽  
Breast Cancers ◽  
Breast Cancer Patients ◽  
Inhibitory Potency ◽  
Clinical Burden ◽  
Helix 12

Acquired resistance to endocrine therapy remains a significant clinical burden for breast cancer patients. Somatic mutations in the ESR1 (estrogen receptor alpha (ERα)) gene ligand-binding domain (LBD) represent a recognized mechanism of acquired resistance. Antiestrogens with improved efficacy versus tamoxifen might overcome the resistant phenotype in ER +breast cancers. Bazedoxifene (BZA) is a potent antiestrogen that is clinically approved for use in hormone replacement therapies. We found that BZA possesses improved inhibitory potency against the Y537S and D538G ERα mutants compared to tamoxifen and has additional inhibitory activity in combination with the CDK4/6 inhibitor palbociclib. In addition, comprehensive biophysical and structural biology studies show BZA’s selective estrogen receptor degrading (SERD) properties that override the stabilizing effects of the Y537S and D538G ERα mutations.

scholarly journals Regulatory Interplay between miR-181a-5p and Estrogen Receptor Signaling Cascade in Breast Cancer

Cancers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 543
Author(s):  
Rosaria Benedetti ◽  
Chiara Papulino ◽  
Giulia Sgueglia ◽  
Ugo Chianese ◽  
Tommaso De Marchi ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Endocrine Therapy ◽  
Mirna Expression ◽  
Estrogen Receptor Alpha ◽  
Estrogen Signaling ◽  
Integrated Analysis ◽  
Tumor Resistance ◽  
Estrogen Receptor Signaling

The efficacy and side effects of endocrine therapy in breast cancer (BC) depend largely on estrogen receptor alpha (ERα) expression, the specific drug administered, and treatment scheduling. Although the benefits of endocrine therapy outweigh any adverse effects in the initial stages of BC, later- or advanced-stage tumors acquire resistance to treatments. The mechanisms underlying tumor resistance to therapy are still not well understood, posing a major challenge for BC patient care. Epigenetic regulation and miRNA expression may be involved in the switch from a treatment-sensitive to a treatment-resistant state and could provide a valid therapeutic strategy for ERα negative BC. Here, a hybrid lysine-specific histone demethylase inhibitor, MC3324, displaying selective estrogen receptor down-regulator-like activities in BC, was used to highlight the interplay between epigenetic and ERα signaling. MC3324 anticancer action is mediated by microRNA (miRNA) expression regulation, indicating an innovative function for this molecule. Integrated analysis suggests a crosstalk between estrogen signaling, ERα interactors, miRNAs, and their putative targets. Specifically, miR-181a-5p expression is regulated by MC3324 and has an impact on cellular levels of ERα. A comparison of breast tumor versus healthy mammary tissues confirmed the important role of miR-181a-5p in ERα regulation and points to its putative predictive function in BC therapy.

Resistance to endocrine therapy in breast cancer: exploiting estrogen receptor/growth factor signaling crosstalk

2006 ◽  
Vol 13 (Supplement_1) ◽  
pp. S15-S24 ◽  
Author(s):  
Suleiman Massarweh ◽  
Rachel Schiff
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Growth Factor ◽  
Endocrine Therapy ◽  
Acquired Resistance ◽  
Growth Factor Signaling ◽  
Breast Cancer Patients ◽  
Signaling Crosstalk ◽  
Receptor Modulator ◽  
Signal Transduction Inhibitors

Targeting the estrogen receptor (ER) is the oldest form of molecular targeted therapy, and the widespread use of the selective estrogen receptor modulator tamoxifen in breast cancer is responsible for major improvements in cure rates, quality of life, and disease prevention in the last 25 years. Newer forms of endocrine therapy now available for the management of endocrine responsive breast cancer include a new generation of aromatase inhibitors, which lower the estrogen ligand for ER, and pure ER antagonists which destroy the receptor. Despite these recent clinical advances, intrinsic and acquired resistance to these endocrine therapies is still a common feature that limits the success of this therapeutic strategy. Recent research into the molecular biology of ER signaling has revealed a remarkably complex interactive signaling with other growth factor signaling pathways in breast cancer cells, potentially explaining some of the reasons behind endocrine therapy action as well as resistance. This view of a more complex ER signaling system has uncovered new molecular targets which, if present in a cancer cell, might be additionally targeted using various signal transduction inhibitors to overcome or prevent resistance to endocrine therapy. In addition, the dynamic inverse relationship between the expression of ER and growth factor receptors brings more excitement to the potential of restoring ER expression in apparently ER-negative cells by inhibition of growth factor signaling. Ongoing clinical trials of endocrine therapy combined with growth factor pathway inhibitors or their downstream signaling elements promise to further improve the present care for breast cancer patients.

Clinical experience using fulvestrant in hormone responsive metastatic breast cancer

2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 10749-10749
Author(s):  
D. O. Bauerschlag ◽  
C. Schem ◽  
W. Jonat ◽  
N. Maass
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Postmenopausal Women ◽  
Clinical Experience ◽  
Aromatase Inhibitors ◽  
Metastatic Breast ◽  
Clinical Situation ◽  
Endocrine Treatment ◽  
Breast Cancer Patients ◽  
Treatment Cascade

10749 Background: We report our clinical experience using the steroid estrogen receptor antagonist Fulvestrant to treat postmenopausal women with hormone sensitive metastasized breast cancer. We discuss the position of Fulvestrant in the endocrine treatment cascade, taking into account the new application guidelines for aromatase inhibitors. Methods: Data from 16 female patients and one male patient treated with Fulvestrant were analyzed. We describe the time point in the treatment cascade when Fulvestrant was administered and the resulting time to progression (TTP). The reviewed cohort was heterogeneous regarding the initial tumor size, the therapy and the progression of the tumor, respectively. The patients were 54 years of age at the time of diagnosis. The estrogen receptor was positive in all cases. Results: Fulvestrant was usually given as the last step in the endocrine treatment cascade (n = 14). The mean TTP was 5.7 months (n = 13). 3 patients are still under successful treatment with Fulvestrant. No common side effects as usually caused by endocrine therapies with Tamoxifen and aromatase inhibitors were documented. Conclusions: The specific estrogen receptor down-regulator Fulvestrant is a valid and well tolerated endocrine treatment option in heavily pre-treated and metastasized breast cancer patients (TTP 5.7 month). Also in the clinical situation of Tamoxifen resistant tumors, Patients could benefit from Fulvestrant. 3rd generation aromatase inhibitors are now used for the first-line treatment of breast cancer in postmenopausal women. Shifting the sequential endocrine therapy cascade might need a new positioning of Fulvestrant. No significant financial relationships to disclose.

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