title: Twist contributes to hormone resistance in breast cancer by downregulating estrogen receptor-α.
abstract: The role of estrogen receptor-α (ER) in breast cancer development, and as a primary clinical marker for breast cancer prognosis, has been well documented. In this study, we identified the oncogenic protein, TWIST1 (Twist), which is overexpressed in high-grade breast cancers, as a potential negative regulator of ER expression. Functional characterization of ER regulation by Twist was performed using Twist low (MCF-7, T-47D) and Twist high (Hs 578T, MDA-MB-231, MCF-7/Twist) expressing cell lines. All Twist high expressing cell lines exhibited low ER transcript and protein levels. By chromatin immunoprecipitation and promoter assays, we demonstrated that Twist could directly bind to E-boxes in the ER promoter and significantly downregulate ER promoter activity in vitro. Functionally, Twist overexpression caused estrogen-independent proliferation of breast cells, and promoted hormone resistance to the selective estrogen receptor modulator tamoxifen and selective estrogen receptor down-regulator fulvestrant. Importantly, this effect was reversible on downregulating Twist. In addition, orthotopic tumors generated in mice using MCF-7/Twist cells were resistant to tamoxifen. These tumors had high vascular volume and permeability surface area, as determined by magnetic resonance imaging (MRI). Mechanistically, Twist recruited DNA methyltransferase 3B (DNMT3B) to the ER promoter, leading to a significantly higher degree of ER promoter methylation compared with parental cells. Furthermore, we demonstrated by co-immunoprecipitation that Twist interacted with histone deacetylase 1 (HDAC1) at the ER promoter, causing histone deacetylation and chromatin condensation, further reducing ER transcript levels. Functional re-expression of ER was achieved using the demethylating agent, 5-azacytidine, and the HDAC inhibitor, valproic acid. Finally, an inverse relationship was observed between Twist and ER expression in human breast tumors. In summary, the regulation of ER by Twist could be an underlying mechanism for the loss of ER activity observed in breast tumors, and may contribute to the generation of hormone-resistant, ER-negative breast cancer.
authors: Russell H Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD 21250, USA. fvesuna1@jhmi.edu
authors: F
authors: F
authors: Vesuna
authors: A
authors: A
authors: Lisok
authors: B
authors: B
authors: Kimble
authors: J
authors: J
authors: Domek
authors: Y
authors: Y
authors: Kato
authors: P
authors: P
authors: van der Groep
authors: D
authors: D
authors: Artemov
authors: J
authors: J
authors: Kowalski
authors: H
authors: H
authors: Carraway
authors: P
authors: P
authors: van Diest
authors: V
authors: V
authors: Raman
mesh_terms: D000107:Acetylation / Q000187:drug effects; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001374:Azacitidine / Q000494:pharmacology; D001943:Breast Neoplasms / Q000098:blood supply / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D002199:Capillary Permeability / Q000187:drug effects; D045744:Cell Line, Tumor; D002843:Chromatin / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects* / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D024721:E-Box Elements / Q000187:drug effects / Q000235:genetics; D047628:Estrogen Receptor alpha / Q000235:genetics*; D004967:Estrogens / Q000378:metabolism; D005260:Female; D056284:Histone Deacetylase 1 / Q000037:antagonists & inhibitors; D006657:Histones / Q000378:metabolism; D006801:Humans; D051379:Mice; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D021381:Protein Transport / Q000187:drug effects; D034741:RNA, Small Interfering / Q000235:genetics; D013629:Tamoxifen / Q000494:pharmacology; D051879:Twist-Related Protein 1 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D014635:Valproic Acid / Q000494:pharmacology; D000097584:DNA Methyltransferase 3B
chemical_list: D000970:Antineoplastic Agents; D001374:Azacitidine; D002843:Chromatin; D004248:DNA (Cytosine-5-)-Methyltransferases; D047628:Estrogen Receptor alpha; D004967:Estrogens; D056284:Histone Deacetylase 1; D006657:Histones; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D013629:Tamoxifen; D051879:Twist-Related Protein 1; D014635:Valproic Acid; D000097584:DNA Methyltransferase 3B; C103173:TWIST1 protein, human; C110550:HDAC1 protein, human