title: Tamoxifen resistance and metastasis of human breast cancer cells were mediated by the membrane-associated estrogen receptor ER-α36 signaling in vitro.
abstract: The drug resistance and tumor metastasis have been the main obstacles for the longer-term therapeutic effects of tamoxifen (TAM) on estrogen receptor-positive (ER+) breast cancer, but the mechanisms underlying the TAM resistance are still unclear. Here, we demonstrated that the membrane-associated estrogen receptor ER-α36 signaling, but not the G protein-coupled estrogen receptor 1 (GPER1) signaling, might be involved in the TAM resistance and metastasis of breast cancer cells. In this study, a model of ER+breast cancer cell MCF-7 that involves the up-regulated expression of ER-α36 and unchanged expression of ER-α66 and GPER1 was established via the removal of insulin from the cell culture medium. The mechanism of TAM resistance in the ER+breast cancer cell line MCF-7 was investigated, and the results showed that the stimulating effect of insulin on susceptibility of MCF-7 to TAM was mediated by ER-α36 and that the expression level of ER-α36 in TAM-resistant MCF-7 cells was also significantly increased. Both TAM and estradiol (E2) could promote the migration of triple negative (ER-α66-/PR-/HER2-) and ER-α36+/GPER1+breast cancer cells MDA-MB-231. The migration of MDA-MB-231 cells was inhibited by the down-regulated intracellular expression of ER-α36 by transient transfection of specific small interfering RNA, whereas no effect of GPER1 down-regulation was observed. Meanwhile, the effect of TAM on the migration of ER-α36-down-regulated MDA-MB-231 cells was also reduced. Furthermore, it was found that TAM enhanced the distribution of integrin β1 on the cell surface but did not affect the expression of integrin β1 in MDA-MB-231 cells. Collectively, these data suggested that ER-α36 signaling might play critical roles in acquired and de novo TAM resistance and metastasis of breast cancer, and ER-α36 might present a potential biomarker of TAM resistance in the clinical diagnosis and treatment of ER+breast cancer.
authors.affiliation: School of Pharmacy, Fudan University, Shanghai, China.|Key Laboratory of Reproduction Regulation of NPFPC, SIPPR, IRD, Fudan University, 2140 Xie Tu Road, Shanghai, 200032, China.
authors.forename: Wenwen
authors.initials: W
authors.lastname: Gu
authors.affiliation: Department of Pulmonary Medicine, The First Affiliated Hospital, Wenzhou Medical University, Wenzhou,, China.
authors.forename: Nian
authors.initials: N
authors.lastname: Dong
authors.affiliation: Key Laboratory of Reproduction Regulation of NPFPC, SIPPR, IRD, Fudan University, 2140 Xie Tu Road, Shanghai, 200032, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Wang
authors.affiliation: Key Laboratory of Reproduction Regulation of NPFPC, SIPPR, IRD, Fudan University, 2140 Xie Tu Road, Shanghai, 200032, China.
authors.forename: Changgen
authors.initials: C
authors.lastname: Shi
authors.affiliation: Key Laboratory of Reproduction Regulation of NPFPC, SIPPR, IRD, Fudan University, 2140 Xie Tu Road, Shanghai, 200032, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Yang
authors.affiliation: School of Pharmacy, Fudan University, Shanghai, China. wangjian@sippr.org.cn.|Key Laboratory of Reproduction Regulation of NPFPC, SIPPR, IRD, Fudan University, 2140 Xie Tu Road, Shanghai, 200032, China. wangjian@sippr.org.cn.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000187:drug effects*; D004958:Estradiol / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000378:metabolism*; D005260:Female; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D019012:Integrin beta1 / Q000378:metabolism; D061986:MCF-7 Cells; D009362:Neoplasm Metastasis; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled; D015398:Signal Transduction / Q000187:drug effects*; D013629:Tamoxifen / Q000494:pharmacology*
chemical_list: D047628:Estrogen Receptor alpha; C109584:GPER1 protein, human; D007328:Insulin; D019012:Integrin beta1; D011960:Receptors, Estrogen; D043562:Receptors, G-Protein-Coupled; C000601334:estrogen receptor alpha 36, human; D013629:Tamoxifen; D004958:Estradiol
keywords: Breast cancer cells; ER-α36; GPER1; Migration; Tamoxifen resistance