scholarly journals Mechanisms of Gefitinib-mediated reversal of tamoxifen resistance in MCF-7 breast cancer cells by inducing ERα re-expression

2015 ◽  
Vol 5 (1) ◽  
Author(s):  
Xia Zhang ◽  
Bin Zhang ◽  
Jie Liu ◽  
Jiwei Liu ◽  
Changzheng Li ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Tamoxifen Resistance ◽  
Mcf 7

scholarly journals Signal Transducer and Activator of Transcription 5b, c-Src, and Epidermal Growth Factor Receptor Signaling Play Integral Roles in Estrogen-Stimulated Proliferation of Estrogen Receptor-Positive Breast Cancer Cells

2008 ◽  
Vol 22 (8) ◽  
pp. 1781-1796 ◽  
Author(s):  
Emily M. Fox ◽  
Teresa M. Bernaciak ◽  
Jie Wen ◽  
Amanda M. Weaver ◽  
Margaret A. Shupnik ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cyclin D1 ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Transcriptional Activity ◽  
Growth Factor Receptor ◽  
Tamoxifen Resistance ◽  
Cancer Proliferation ◽  
Epidermal Growth ◽  
Mcf 7

Abstract 17β-Estradiol (E2) acts through the estrogen receptor α (ERα) to stimulate breast cancer proliferation. Here, we investigated the functional relationship between ERα and signal transducer and activator of transcription (STAT)5b activity in ER+ MCF-7 and T47D human breast cancer cells after specific knockdown of STAT5b. STAT5b small interfering RNA (siRNA) inhibited E2-induced bromodeoxyuridine (BrdU) incorporation in both cell lines, as well as the E2-induced increase in MCF-7 cell number, cyclin D1 and c-myc mRNA, and cyclin D1 protein expression, indicating that STAT5b is required for E2-stimulated breast cancer proliferation. E2 treatment stimulated STAT5b tyrosine phosphorylation at the activating tyrosine Y699, resulting in increased STAT5-mediated transcriptional activity, which was inhibited by a Y669F STAT5b mutant. E2-induced STAT5-mediated transcriptional activity was inhibited by overexpressing a kinase-defective epidermal growth factor receptor (EGFR), or the EGFR tyrosine kinase inhibitor tyrphostin AG1478, indicating a requirement for EGFR kinase activity. Both E2-induced STAT5b tyrosine phosphorylation and STAT5-mediated transcription were also inhibited by the ER antagonist ICI 182,780 and the c-Src inhibitor PP2, indicating additional requirements for the ER and c-Src kinase activity. EGFR and c-Src kinase activities were also required for E2-induced cyclin D1 and c-myc mRNA. Together, these studies demonstrate positive cross talk between ER, c-Src, EGFR, and STAT5b in ER+ breast cancer cells. Increased EGFR and c-Src signaling is associated with tamoxifen resistance in ER+ breast cancer cells. Here we show that constitutively active STAT5b not only increased basal DNA synthesis, but also conferred tamoxifen resistance. Because STAT5b plays an integral role in E2-stimulated proliferation and tamoxifen resistance, it may be an effective therapeutic target in ER+ breast tumors.

scholarly journals Cyclooxygenase-2 utilizes Jun N-terminal kinases to induce invasion, but not tamoxifen resistance, in MCF-7 breast cancer cells

2013 ◽  
Vol 30 (3) ◽  
pp. 1506-1510 ◽  
Author(s):  
VIANEY GONZALEZ-VILLASANA ◽  
YOLANDA GUTIÉRREZ-PUENTE ◽  
ANA M. TARI
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Tamoxifen Resistance ◽  
Cyclooxygenase 2 ◽  
Mcf 7

scholarly journals miR-200 affects tamoxifen resistance in breast cancer cells through regulation of MYB

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Yu Gao ◽  
Wenzhi Zhang ◽  
Chengwen Liu ◽  
Guanghua Li
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Tamoxifen Resistance ◽  
Breast Cancer Patients ◽  
Over Expression ◽  
Er Positive ◽  
Emt Markers ◽  
Mcf 7 ◽  
Positive Breast Cancer

AbstractResistance to tamoxifen is a major clinical challenge. Research in recent years has identified epigenetic changes as mediated by dysregulated miRNAs that can possibly play a role in resistance to tamoxifen in breast cancer patients expressing estrogen receptor (ER). We report here elevated levels of EMT markers (vimentin and ZEB1/2) and reduced levels of EMT-regulating miR-200 (miR-200b and miR-200c) in ER-positive breast cancer cells, MCF-7, that were resistant to tamoxifen, in contrast with the naïve parental MCF-7 cells that were sensitive to tamoxifen. Further, we established regulation of c-MYB by miR-200 in our experimental model. C-MYB was up-regulated in tamoxifen resistant cells and its silencing significantly decreased resistance to tamoxifen and the EMT markers. Forced over-expression of miR-200b/c reduced c-MYB whereas reduced expression of miR-200b/c resulted in increased c-MYB We further confirmed the results in other ER-positive breast cancer cells T47D cells where forced over-expression of c-MYB resulted in induction of EMT and significantly increased resistance to tamoxifen. Thus, we identify a novel mechanism of tamoxifen resistance in breast tumor microenvironment that involves miR-200-MYB signaling.

scholarly journals MTDH Mediates Estrogen-Independent Growth and Tamoxifen Resistance by Down-Regulating PTEN in MCF-7 Breast Cancer Cells

2014 ◽  
Vol 33 (5) ◽  
pp. 1557-1567 ◽  
Author(s):  
Chunyuan Xu ◽  
Xiaoli Kong ◽  
Haiji Wang ◽  
Ning Zhang ◽  
Xiangnan Kong ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Tamoxifen Resistance ◽  
Mcf 7

scholarly journals The Effect of Canertinib on Sensitivity of Cytotoxic Drugs in Tamoxifen-Resistant Breast Cancer Cells In Vitro

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Hesham A. M. Gomaa ◽  
Asmaa T. Ali ◽  
M. Abdel Gabbar ◽  
M. A. Kandeil
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Kinase Inhibitor ◽  
Apoptotic Cell ◽  
Combined Treatment ◽  
Single Agent ◽  
Tamoxifen Resistance ◽  
Cytotoxic Drugs ◽  
Mcf 7

Aims and Objectives. To investigate and examine the reversal effects of canertinib on the activity of EGFR and tamoxifen resistance in drug-resistant human breast carcinoma cells (MCF-7/TamR). Materials and Methods. The antiproliferative activity of canertinib alone or in combination with a conventional EGFR-targeting chemotherapies cytotoxic drugs differing in the mechanism(s) of action, such as paclitaxel, carboplatin, etoposide, vinorelbine, and daunorubicin as well as resistance mechanisms of EGFR targeting, have been investigated. Results. With an elevated dosage of canertinib, a significant decrease in proliferation and increase in apoptosis was observed. The treatment with higher doses of canertinib resulted in a 2-3-fold increase in apoptosis. In the combined treatment, it had been noticed a significant developed apoptotic cell death rather induced by single agent treatment. A significant downregulation of the antiapoptotic protein bcl-2 was exposed by immunocytochemistry investigation. Sensitivity to paclitaxel was also measured and was found to inversely correlate to bcl-2 status. Conclusion. Proliferation inhibition and apoptosis in MCF-7/TAM-R cells increase with increasing dosage of canertinib. This suggests that canertinib can reverse tamoxifen resistance in breast cancer cells. The antitumor effect of this EGFR-irreversible tyrosine kinase inhibitor provides a rationale for its clinical evaluation in combination with other cytotoxic drugs.

scholarly journals miR-449a Suppresses Tamoxifen Resistance in Human Breast Cancer Cells by Targeting ADAM22

2018 ◽  
Vol 50 (1) ◽  
pp. 136-149 ◽  
Author(s):  
Jun Li ◽  
Mingjie Lu ◽  
Jiao Jin ◽  
Xiyi Lu ◽  
Tongpeng Xu ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Tamoxifen Resistance ◽  
Luciferase Assay ◽  
Protein Protein Interaction ◽  
Er Positive ◽  
Tamoxifen Resistant ◽  
Mcf 7 ◽  
Positive Breast Cancer

Background/Aims: Most of estrogen receptor positive breast cancer patients respond well initially to endocrine therapies, but often develop resistance during treatment with selective estrogen receptor modulators (SERMs) such as tamoxifen. Altered expression and functions of microRNAs (miRNAs) have been reportedly associated with tamoxifen resistance. Thus, it is necessary to further elucidate the function and mechanism of miRNAs in tamoxifen resistance. Methods: Tamoxifen sensitivity was validated by using Cell Counting Kit-8 in tamoxifen-sensitive breast cancer cells (MCF-7, T47D) and tamoxifen-resistant cells (MCF-7/TAM, T47D/ TAM). Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect the expression level of miR-449a in tamoxifen-sensitive/-resistant cells and patient serums. Dual-luciferase assay was used to identify the binding of miR-449a and predicted gene ADAM22. The expression level of ADAM22 was determined by qRT-PCR and western blotting in miR-449a +/- breast cancer cells. Subsequently, rescue experiments were carried out to identify the function of ADAM22 in miR-449a-reduced tamoxifen resistance. Finally, Gene ontology (GO) and Protein-protein interaction analyses were performed to evaluate the potential mechanisms of ADAM22 in regulating tamoxifen resistance. Results: MiR-449a levels were downregulated significantly in tamoxifen-resistant breast cancer cells when compared with their parental cells, as well as in clinical breast cancer serum samples. Overexpression of miR-449a re-sensitized the tamoxifen-resistant breast cancer cells, while inhibition of miR-449a conferred tamoxifen resistance in parental cells. Luciferase assay identified ADAM22 as a direct target gene of miR-449a. Additionally, silencing of ADAM22 could reverse tamoxifen resistance induced by miR-449a inhibition in ER-positive breast cancer cells. GO analysis results showed ADAM22 was mainly enriched in the biological processes of cell adhesion, cell differentiation, gliogenesis and so on. Protein-protein interaction analyses appeared that ADAM22 might regulate tamoxifen resistance through PPARG, LGI1, KRAS and LYN. Conclusion: Decreased miR-449a causes the upregulation of ADAM22, which induces tamoxifen resistance of breast cancer cells. These results suggest that miR-449a, functioning by targeting ADAM22, contributes to the mechanisms underlying breast cancer endocrine resistance, which may provide a potential therapeutic strategy in ER-positive breast cancers.

scholarly journals Overexpression of TMEM47 Induces Tamoxifen Resistance in Human Breast Cancer Cells

2021 ◽  
Vol 20 ◽  
pp. 153303382110049
Author(s):  
Xin Men ◽  
Mengyang Su ◽  
Jun Ma ◽  
Yueyang Mou ◽  
Penggao Dai ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Viability ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Tamoxifen Resistance ◽  
Cancer Cell Line ◽  
Mcf7 Cells ◽  
Premenopausal Breast Cancer ◽  
Hormone Receptor Positive ◽  
Mcf 7

Background: Tamoxifen (TAM) is the eminent first-line drug for endocrine therapy of hormone receptor positive premenopausal breast cancer and reduces the risk of recurrence by ∼50%. However, many patients developed TAM resistance and their diseases recurred. Our previous study on transcriptome profile of TAM resistant breast cancer cells revealed that the TMEM47 is one of the most significantly differentially expressed genes. The mechanism of how TMEM47 is involved in TAM resistance was not known. Methods: We constructed a mammal breast cancer cell line, in which TMEM47 was stably overexpressed (TMEM47-OE/MCF-7), to further verify the role of TMEM47 in TAM resistance. siRNA targeting TMEM47 was transfected into TAMR / MCF-7 cells by Liposome. TMEM47 expression was validated on mRNA and protein level by qRT-PCR and western blotting. We tested the cytotoxicity of TAM in the cells. Apoptosis was detected by flow cytometry. Results: Compared to the MCF7 cells, TMEM47 mRNA was significantly up regulated more than 6 folds in the TAMR/MCF7 cells and so its protein. TMEM47 expression level in TMEM47-OE/MCF-7 was similar as in the TAMR/MCF-7 cells. The 50% inhibitory concentration (IC50) value (mean ± SD) of TAM in MCF-7, TAMR/MCF-7 and TMEM47-OE/MCF-7 cells was 1.58 ± 0.19, 2.74 ± 0.24 and 3.12 ± 0.32 µγ/mL, respectively. The apoptosis rates of TAMR/MCF-7 and TMEM47-OE/MCF-7 cell lines were significantly lower than that of MCF-7 cells. After 24 and 48 hours TAM treatments, cell viability was significantly inhibitied in TMEM47 knockdown TAMR/MCF7 cells (P < 0.01). Consistant with the decreased cell viability, the apoptosis rate in TMEM47 knockdown TAMR/MCF-7 cells was significantly increased. Conclusions: Our results suggest that overexpression of TMEM47 in MCF-7 cells acquired TAM resistance to those cells, and knockdown of TMEM47 in TAMR/MCF-7 cells reversed their resistance to TAM. TMEM47 might confer TAM resistance on MCF-7 cells through the inhibition of apoptosis.

Effect of estrogen receptor-positive progenitor cells on a tamoxifen resistance phenotype in breast cancer cells

2009 ◽  
Vol 27 (15_suppl) ◽  
pp. 1042-1042
Author(s):  
J. Selever ◽  
I. Barone ◽  
M. T. Lewis ◽  
A. Corona-Rodriguez ◽  
A. Tsimelzon ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Estrogen Receptor ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Tamoxifen Resistance ◽  
Soft Agar ◽  
Estrogen Receptor Positive ◽  
Mcf 7 ◽  
Positive Breast Cancer

1042 Background: The antiestrogen tamoxifen and aromatase inhibitors are the most frequently prescribed hormonal agents for the treatment of estrogen receptor (ER) α-positive breast cancer. An important question is whether there is a group of hormone resistant, ERα-positive patients who may derive additional benefit from the addition of chemotherapy to endocrine therapy, or who may be candidates for “targeted” biologics. Dicer1 is an RNase III-containing enzyme that processes microRNA precursors into mature microRNA, which have been implicated in breast tumor invasion and metastasis. BCRP1 is a transmembrane transport protein known to efflux a number of chemotherapeutic agents, but also steroid hormones. In the present study, we investigated whether Dicer might affect response to tamoxifen in breast cancer cells, and generated estrogen receptor-positive MCF-7 human breast cancer cells stably overexpressing Dicer1, and they exhibited elevated BCRP1 protein. Methods: We utilized preclinical approaches to study the function of BCRP1 in Dicer-overexpressing breast cancer cells using in vitro growth assays in soft agar, mammosphere formation assays, and in vivo tumor initiation. Results: Microarray analyses of human breast tumors, suggested that Dicer overexpression was associated with tamoxifen resistance. Dicer-overexpressing MCF-7 cells express elevated levels of BCRP1, ALDH, and cErbB2/HER-2 evident by immunoblot analysis. The Dicer1-overexpressing cells formed soft agar colonies in the presence of tamoxifen, however Fumitremorgin C (FTC) or MBLI-97, both BCRP inhibitors, reversed resistance, and sensitized cells to tamoxifen therapy. Preclinical in vivo tumor xenograft experiments confirmed the tamoxifen-resistant phenotype. Mammosphere potential was enhanced in Dicer-overexpressing cells suggesting an enrichment of stem-like breast cancer cells. Conclusions: Our results suggest that Dicer-overexpressing breast cancer cells are a novel preclinical model for an estrogen receptor-positive breast cancer progenitor phenotype and tamoxifen resistance. Based on our data Dicer1 is a potential predictive biomarker in breast cancer, and predicts that clinical BCRP1 inhibition may facilitate tumor sensitization to hormonal therapy. No significant financial relationships to disclose.

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