scholarly journals miR-489 Confines Uncontrolled Estrogen Signaling Through a Negative Feedback Mechanism and Regulates Tamoxifen Resistance in Breast Cancer

2022 ◽  
Author(s):  
Mithil Soni ◽  
Ozge Saatci ◽  
Gourab Gupta ◽  
Yogin Patel ◽  
Manikanda Raja Keerthi Raja ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Cell Lines ◽  
Tamoxifen Resistance ◽  
Resistant Cell ◽  
Estrogen Signaling ◽  
Breast Cancers ◽  
Tamoxifen Resistant ◽  
Hormonal Therapies

Abstract Background: Approximately 75% of diagnosed breast cancer tumors are estrogen-receptor (ER) positive tumors and are associated with better prognosis due to their response to hormonal therapies. However, around 40% of patients relapse after hormonal therapies. In the current study, we aim to evaluate miR-489 as a novel molecular target to combat tamoxifen resistance. Methods: Genomic analysis of gene expression profiles in primary breast cancers and tamoxifen resistant cell lines unveiled the potential role of miR-489 in regulation of estrogen signaling and development of tamoxifen resistance. We manipulated miR-489 expression in breast cancer cell lines by transient transfection of a miR-489 mimic or establishment of knockout cell lines using the CRISPR/Cas9 system to study the reciprocal regulation of miR-489 and estrogen/ER signaling pathways. Cell proliferation assays, Sphere-formation assays and flow cytometry analysis were conducted to investigate the role of miR-489 in estrogen-induced cell proliferation, cancer stem cell expansion and development of tamoxifen resistance. Results: miR-489 expression was significantly downregulated in tamoxifen-resistant cell lines. Low levels of miR-489 were associated with poor clinical outcomes in patients with hormone treatment. In vitro analysis showed that loss of miR-489 expression promoted tamoxifen resistance while overexpression of miR-489 in tamoxifen-resistant cells restored tamoxifen sensitivity. Mechanistically, we found that miR-489 is an estrogen regulated miRNA that negatively regulated estrogen receptor signaling by using at least the following two mechanisms: i) modulation of ER phosphorylation status by inhibiting MAPK and AKT kinase activities and downregulating SHP2 expression; ii) regulation of nucleus to cytosol translocation of estrogen receptor α (ERα) by decreasing p38 expression and consequently ER phosphorylation. In addition, miR-489 could break the positive feed-forward loop between the estrogen-ERα axis and p38 MAPK in breast cancer cells, which was necessary for its function as a transcription factor. Conclusion: Our study unveiled the underlying molecular mechanism by which miR-489 regulates estrogen signaling pathway through a negative feedback loop and uncovered its role in both the development of and overcoming of tamoxifen resistance in breast cancers.

scholarly journals miR-489 confines uncontrolled estrogen signaling through a negative feedback mechanism and regulates tamoxifen resistance in breast cancer

2020 ◽  
Author(s):  
Mithil Soni ◽  
Ozge Saatci ◽  
Yogin Patel ◽  
Manikanda Raja Keerthi Raja ◽  
Xinfeng Liu ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Cell Lines ◽  
Tamoxifen Resistance ◽  
Resistant Cell ◽  
Estrogen Signaling ◽  
Breast Cancers ◽  
Tamoxifen Resistant ◽  
Hormonal Therapies

Abstract Background Approximately 75% of diagnosed breast cancer tumors are Estrogen receptor (ER) positive tumors and are associated with better prognosis due to their response to hormonal therapies. However, around 40% of patients relapse after hormonal therapies. In the current study, we aimed to evaluate miR-489 as a novel molecular target to combat tamoxifen resistance.Methods Genomic analysis of gene expression profiles in primary breast cancers and tamoxifen resistant cell lines unveiled the potential role of miR-489 in regulation of estrogen signaling and development of tamoxifen resistance. We manipulated miR-489 expression in breast cancer cell lines by transient transfection of miR-489 mimic or establishment of knockout cell lines using the CRISPR/Cas9 system to study the reciprocal regulation of miR-489 and estrogen/ER signaling pathways. Cell proliferation, tumor sphere formation assay and flow cytometry analysis were conducted to investigate the role of miR-489 on estrogen-induced cell proliferation, cancer stem cells expansion and development of tamoxifen resistance.Results miR-489 expression was significantly downregulated in tamoxifen-resistant cell lines. Low levels of miR-489 were associated with poor clinical outcomes in patients with hormone treatment. In vitro analysis showed that loss of miR-489 expression promoted tamoxifen resistance while overexpression of miR-489 in tamoxifen-resistant cells restored tamoxifen sensitivity. Mechanistically, we found that miR-489 is an estrogen regulated miRNA that negatively regulated estrogen receptor signaling by using at least the following two mechanisms: i) modulation of ER phosphorylation status by inhibiting MAPK and AKT kinase activities; ii) regulation of nucleus to cytosol translocation of estrogen receptor α (ERα) by decreasing p38 expression and consequently ER phosphorylation. In addition, miR-489 could break the positive feed-forward loop between estrogen-ERα axis and p38 MAPK in breast cancer cells which was necessary for its function as transcription factor.Conclusion Our study unveiled the underlying molecular mechanism by which miR-489 regulates estrogen signaling pathway through a negative feedback loop and uncovered its role in the development of and overcoming tamoxifen resistance in breast cancers.

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.

scholarly journals Poly-ADP-Ribosylation of Estrogen Receptor-Alpha by PARP1 Mediates Antiestrogen Resistance in Human Breast Cancer Cells

Cancers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 43 ◽  
Author(s):  
Nicholas Pulliam ◽  
Jessica Tang ◽  
Weini Wang ◽  
Fang Fang ◽  
Riddhi Sood ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Oxidative Stress ◽  
Estrogen Receptor ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Target Genes ◽  
Tamoxifen Resistance ◽  
Tamoxifen Treatment ◽  
Dependent Manner ◽  
Tamoxifen Resistant

Therapeutic targeting of estrogen receptor-α (ERα) by the anti-estrogen tamoxifen is standard of care for premenopausal breast cancer patients and remains a key component of treatment strategies for postmenopausal patients. While tamoxifen significantly increases overall survival, tamoxifen resistance remains a major limitation despite continued expression of ERα in resistant tumors. Previous reports have described increased oxidative stress in tamoxifen resistant versus sensitive breast cancer and a role for PARP1 in mediating oxidative damage repair. We hypothesized that PARP1 activity mediated tamoxifen resistance in ERα-positive breast cancer and that combining the antiestrogen tamoxifen with a PARP1 inhibitor (PARPi) would sensitize tamoxifen resistant cells to tamoxifen therapy. In tamoxifen-resistant vs. -sensitive breast cancer cells, oxidative stress and PARP1 overexpression were increased. Furthermore, differential PARylation of ERα was observed in tamoxifen-resistant versus -sensitive cells, and ERα PARylation was increased by tamoxifen treatment. Loss of ERα PARylation following treatment with a PARP inhibitor (talazoparib) augmented tamoxifen sensitivity and decreased localization of both ERα and PARP1 to ERα-target genes. Co-administration of talazoparib plus tamoxifen increased DNA damage accumulation and decreased cell survival in a dose-dependent manner. The ability of PARPi to overcome tamoxifen resistance was dependent on ERα, as lack of ERα-mediated estrogen signaling expression and showed no response to tamoxifen-PARPi treatment. These results correlate ERα PARylation with tamoxifen resistance and indicate a novel mechanism-based approach to overcome tamoxifen resistance in ER+ breast cancer.

scholarly journals Inhibiting PAD2 enhances the anti-tumor effect of docetaxel in tamoxifen-resistant breast cancer cells

2019 ◽  
Vol 38 (1) ◽  
Author(s):  
Fujun Li ◽  
Lixia Miao ◽  
Teng Xue ◽  
Hao Qin ◽  
Santanu Mondal ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Combination Treatment ◽  
Breast Cancer Cells ◽  
Tamoxifen Resistance ◽  
Nuclear Accumulation ◽  
Breast Cancers ◽  
Inhibition Of Proliferation ◽  
Tamoxifen Resistant

Abstract Background Tamoxifen resistance presents a huge clinical challenge for breast cancer patients. An understanding of the mechanisms of tamoxifen resistance can guide development of efficient therapies to prevent drug resistance. Methods We first tested whether peptidylarginine deiminase 2 (PAD2) may be involved in tamoxifen-resistance in breast cancer cells. The effect of depleting or inhibiting PAD2 in tamoxifen-resistant MCF-7 (MCF7/TamR) cells was evaluated both in vitro and in vivo. We then investigated the potential of Cl-amidine, a PAD inhibitor, to be used in combination with tamoxifen or docetaxel, and further explored the mechanism of the synergistic and effective drug regimen of PADs inhibitor and docetaxel on tamoxifen-resistant breast cancer cells. Results We report that PAD2 is dramatically upregulated in tamoxifen-resistant breast cancer. Depletion of PAD2 in MCF7/TamR cells facilitated the sensitivity of MCF7/TamR cells to tamoxifen. Moreover, miRNA-125b-5p negatively regulated PAD2 expression in MCF7/TamR cells, therefore overexpression of miR-125b-5p also increased the cell sensitivity to tamoxifen. Furthermore, inhibiting PAD2 with Cl-amidine not only partially restored the sensitivity of MCF7/TamR cells to tamoxifen, but also more efficiently enhanced the efficacy of docetaxel on MCF7/TamR cells with lower doses of Cl-amidine and docetaxel both in vivo and in vivo. We then showed that combination treatment with Cl-amidine and docetaxel enhanced p53 nuclear accumulation, which synergistically induced cell cycle arrest and apoptosis. Meanwhile, p53 activation in the combination treatment also accelerated autophagy processes by synergistically decreasing the activation of Akt/mTOR signaling, thus enhancing the inhibition of proliferation. Conclusion Our results suggest that PAD2 functions as an important new biomarker for tamoxifen-resistant breast cancers and that inhibiting PAD2 combined with docetaxel may offer a new approach to treatment of tamoxifen-resistant breast cancers.

A novel therapeutic strategy for ER-negative human breast cancers, targeting AP-1 activity

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 14129-14129
Author(s):  
K. Sakaguchi ◽  
H. Nakajima ◽  
I. Fujiwara ◽  
N. Mizuta ◽  
J. Magae
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Cell Lines ◽  
Cancer Cell ◽  
Breast Cancer Cell ◽  
Human Breast Cancer ◽  
Human Breast Cancer Cell ◽  
Breast Cancers ◽  
Human Breast ◽  
Er Positive

14129 Background: While agents targeting estrogen receptors are the most effective in adjuvant therapy for human breast cancers expressing estrogen receptor(ER), breast cancers lacking ER are clinically serious, because they are highly malignant and exhibit resistance to the usual anti-cancer drugs, including estrogen receptor-antagonists and DNA breaking agents. Although a transcription factor, AP-1, is known to be related to tumor malignancy including metastasis, invasion and drug-resistance, it remains to be elucidated how AP-1 plays in development and expression of malignant characters of human breast cancers. Methods and Results: Here, we used MX-1, a human breast cancer cell line lacking ER and several ER positive cell lines, to clarify the roles of AP-1 and the therapeutic efficacy of ascochlorin, a newly developed prenylphenol antibiotic on ER-negative breast cancer. We found that MX-1 exhibited higher AP-1 activity and expressed higher levels of c-Jun, c-Fos and Fra-1 when compared with conventional ER-positive human breast cancer cell lines. Consistent with this study in vitro, histological study on human breast cancer tissues suggests that ER-negative cancers express high Fra-1 protein, and that paclitaxel- sensitive cancers express low Fra-1 protein. The ascochlorin, which inhibits AP-1 through the Erk signaling pathway, suppressed the AP-1 activity of MX-1 cells, and selectively killed MX-1 cells, partly due to induction of apoptosis. Moreover, administration of ascochlorin elongated life span of mice intraperitoneally implanted with murine mammary carcinoma cells. Conclusions: Our results suggest that AP-1 is an effective clinical target molecule for the treatment of ER-negative human breast cancer, and that ascochlorin is promising therapeutic agent for these refractory breast cancers. No significant financial relationships to disclose.

Molecular Changes in Tamoxifen-Resistant Breast Cancer: Relationship Between Estrogen Receptor, HER-2, and p38 Mitogen-Activated Protein Kinase

2005 ◽  
Vol 23 (11) ◽  
pp. 2469-2476 ◽  
Author(s):  
M. Carolina Gutierrez ◽  
Simone Detre ◽  
Stephen Johnston ◽  
Syed K. Mohsin ◽  
Jiang Shou ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Protein Kinase ◽  
Tamoxifen Resistance ◽  
Mitogen Activated Protein Kinase ◽  
Clinical Samples ◽  
Strong Correlations ◽  
Mitogen Activated Protein ◽  
Her 2 ◽  
Tamoxifen Resistant

Purpose To evaluate growth factor receptor cross talk with the estrogen receptor (ER) in paired clinical breast cancer specimens and in a xenograft model before tamoxifen and at tumor progression as a possible mechanism for tamoxifen resistance. Methods Specimen pairs from 39 patients were tissue arrayed and stained for ER, progesterone receptor (PgR), Bcl-2, c-ErbB2 (HER-2), and phosphorylated (p) p38 mitogen-activated protein kinase (MAPK), p-ERK1/2 MAPK, and p-Akt. Xenograft MCF-7 tumors before and after tamoxifen resistance were assessed for levels of p-p38. Results Pretreatment, there were strong correlations between ER, PgR, and Bcl-2, and an inverse correlation between ER and HER-2. These correlations were lost in the tamoxifen- resistant tumors and replaced by strong correlations between ER and p-p38 and p-ERK. ER expression was lost in 17% of resistant tumors. Three (11%) of the 26 tumors originally negative for HER-2 became amplified and/or overexpressed at resistance. All ER-positive tumors that overexpressed HER-2 originally or at resistance expressed high levels of p-p38. In the pretreatment and tamoxifen-resistant specimens, there were strong correlations between p-p38 and p-ERK. In the tamoxifen-resistant xenograft tumors, like the clinical samples, there was a striking increase in p-p38. Conclusion The molecular pathways driving tumor growth can change as the tumor progresses. Crosstalk between ER, HER-2, p38, and ERK may contribute to tamoxifen resistance and may provide molecular targets to overcome this resistance.

scholarly journals Endocrine therapy resistance can be associated with high estrogen receptor α (ERα) expression and reduced ERα phosphorylation in breast cancer models

2006 ◽  
Vol 13 (4) ◽  
pp. 1121-1133 ◽  
Author(s):  
Barbara Kuske ◽  
Catherine Naughton ◽  
Kate Moore ◽  
Kenneth G MacLeod ◽  
William R Miller ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Cell Lines ◽  
Therapy Resistance ◽  
Estrogen Receptor Α ◽  
Cancer Models ◽  
Er Positive ◽  
Tamoxifen Resistant ◽  
Trefoil Factor 1 ◽  
Mcf 7

Hormone-dependent estrogen receptor (ER)-positive breast cancer cells may adapt to low estrogen environments such as produced by aromatase inhibitors. In many instances, cells become insensitive to the effects of estrogen but may still retain dependence on ER. We have investigated the expression, function, and activation of ERα in two endocrine-resistant MCF-7 models to identify mechanisms that could contribute to resistance. While MCF-7/LCC1 cells are partially estrogen dependent, MCF-7/LCC9 cells are fully estrogen insensitive and fulvestrant and tamoxifen resistant. In both MCF-7/LCC1 and MCF-7/LCC9 cell lines, high expression of ERα was associated with enhanced binding to the trefoil factor 1 (TFF1) promoter in the absence of estrogen and increased transcription of TFF1 and progesterone receptor. In contrast to the observations derived from hypersensitive and supersensitive models, these cells were truly estrogen independent; nevertheless, removal of ERα by siRNA, or fulvestrant, a specific ER downregulator, inhibited growth indicating dependence on ERα. In the absence of estrogen, neither ERα Ser118 nor Ser167 were phosphorylated as frequently found in other ligand-independent cell line models. Addition of estrogen activated ERα Ser118 in MCF-7 and LCC1 cells but not in LCC9 cells. We suggest that the estrogen-independent growth within these cell lines is accounted for by high levels of ERα expression driving transcription and full estrogen independence explained by lack of ERα activation through Ser118.

scholarly journals GREB1 regulates proliferation of estrogen receptor positive breast cancer through modulation of PI3K/Akt/mTOR signaling

2019 ◽  
Author(s):  
Corinne N. Haines ◽  
H.D. Klingensmith ◽  
Craig J. Burd
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Growth Regulation ◽  
Mtor Pathway ◽  
Estrogen Signaling ◽  
Molecular Function ◽  
Breast Cancers ◽  
Gene Target

AbstractOver 70% of breast cancers express the estrogen receptor (ER) and depend on ER activity for survival and proliferation. While hormone therapies that target receptor activity are initially effective, patients invariably develop resistance which is often associated with activation of the PI3K/Akt/mTOR pathway. While the mechanism by which estrogen regulates proliferation is not fully understood, one gene target of ER, growth regulation by estrogen in breast cancer 1 (GREB1), is required for hormone-dependent proliferation. However, the molecular function by which GREB1 regulates proliferation is unknown. Herein, we validate that knockdown of GREB1 results in growth arrest and that exogenous GREB1 expression initiates oncogene-induced senescence, suggesting that an optimal level of GREB1 expression is necessary for proliferation of breast cancer cells. Under both of these conditions, GREB1 is able to regulate signaling through the PI3K/Akt/mTOR pathway. GREB1 acts intrinsically through PI3K to regulate PIP3 levels and Akt activity. Critically, growth suppression of estrogen-dependent breast cancer cells by GREB1 knockdown is rescued by expression of constitutively activated Akt. Together, these data identify a novel molecular function by which GREB1 regulates breast cancer proliferation through Akt activation and provides a mechanistic link between estrogen signaling and the PI3K pathway.

scholarly journals MiR-195 and Its Target SEMA6D Regulate Chemoresponse in Breast Cancer

Cancers ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 5979
Author(s):  
Diana E. Baxter ◽  
Lisa M. Allinson ◽  
Waleed S. Al Amri ◽  
James A. Poulter ◽  
Arindam Pramanik ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Cell Lines ◽  
Target Genes ◽  
Breast Cancer Cell Lines ◽  
Molecular Characteristics ◽  
Chemotherapy Response ◽  
Breast Cancers ◽  
Microrna Target ◽  
Estrogen Receptor Positive

Background: poor prognosis primary breast cancers are typically treated with cytotoxic chemotherapy. However, recurrences remain relatively common even after this aggressive therapy. Comparison of matched tumours pre- and post-chemotherapy can allow identification of molecular characteristics of therapy resistance and thereby potentially aid discovery of novel predictive markers or targets for chemosensitisation. Through this comparison, we aimed to identify microRNAs associated with chemoresistance, define microRNA target genes, and assess targets as predictors of chemotherapy response. Methods: cancer cells were laser microdissected from matched breast cancer tissues pre- and post-chemotherapy from estrogen receptor positive/HER2 negative breast cancers showing partial responses to epirubicin/cyclophosphamide chemotherapy (n = 5). MicroRNA expression was profiled using qPCR arrays. MicroRNA/mRNA expression was manipulated in estrogen receptor positive/HER2 negative breast cancer cell lines (MCF7 and MDA-MB-175 cells) with mimics, inhibitors or siRNAs, and chemoresponse was assessed using MTT and colony forming survival assays. MicroRNA targets were identified by RNA-sequencing of microRNA mimic pull-downs, and comparison of these with mRNAs containing predicted microRNA binding sites. Survival correlations were tested using the METABRIC expression dataset (n = 1979). Results: miR-195 and miR-26b were consistently up-regulated after therapy, and changes in their expression in cell lines caused significant differences in chemotherapy sensitivity, in accordance with up-regulation driving resistance. SEMA6D was defined and confirmed as a target of the microRNAs. Reduced SEMA6D expression was significantly associated with chemoresistance, in accordance with SEMA6D being a down-stream effector of the microRNAs. Finally, low SEMA6D expression in breast cancers was significantly associated with poor survival after chemotherapy, but not after other therapies. Conclusions: microRNAs and their targets influence chemoresponse, allowing the identification of SEMA6D as a predictive marker for chemotherapy response that could be used to direct therapy or as a target in chemosensitisation strategies.

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