Dengyin-2014-ER-alpha variant ER-.pdf

Journal of Steroid Biochemistry Molecular Biology 144 (2014) 417–426ER-a variant ER-a36 mediates antiestrogen resistance in ER-positive breast cancer stem/progenitor cells Hao Deng a,1, Li Yin a,1, Xin-Tian Zhang a, Li-Jiang Liu b, Mo-Lin Wang c, Zhao-Yi Wang a,* aDepartments of Medical Microbiology and Immunology, Creighton University Medical School, Omaha, NE, USA b Jiangda Pathology Center, Jianghan University, Wuhan, Hubei, PR China c Institute of Medical Genetics, School of Medicine, Shandong University, Jinan, Shandong, PR China A R T I C L E I N F O Article history: Received 14 March 2014 Received in revised form 29 May 2014 Accepted 21 August 2014 Available online 23 August 2014 Keywords: ER-a36 Antiestrogen resistance ER-positive breast cancer Cancer stem/progenitor cells A B S T R A C T Accumulating evidence indicates that cancer stem cells (CSC) play important roles in breast cancer occurrence, recurrence and metastasis as well as resistance to therapy. However, the roles of breast cancer stem cells in antiestrogen resistance and the underlying molecular mechanisms have not been well established. Previously, we identified and cloned a novel variant of estrogen receptor a, ER-a36, with a molecular weight of 36 kDa. ER-a36 mediates rapid antiestrogen signaling and is highly expressed in ER-positive breast cancer stem/progenitor cells. In this study, we investigated the function and the underlying mechanism of ER-a36-mediated antiestrogen signaling in ER-positive breast cancer stem/progenitor cells. ER-positive breast cancer cells MCF7 and T47D as well as variants with different levels of ER-a36 expression were used. The effects of antiestrogens tamoxifen and ICI 182, 780 on breast CSC’s ability of growth, self-renewal, differentiation and tumor seeding were examined using tumorsphere formation, flow cytometry, indirect immunofluorences and in vivo xenograft assays. The underlying mechanisms were also analyzed with Western blot analysis. We found that the c