Abstract:

Objective   To investigate the role of transforming growth factor-β1 (TGF-β1) induced prostate transmembrane protein, androgen induced 1 (TMEPAI) playing in the progress of breast cancer and its mechanism. Methods   TMEPAI protein levels in estrogen receptor/progesterone receptor-negative and human epidermal growth factor receptor-2-negative breast cancer tissues, breast cancer cell lines and normal breast tissues were detected using Western blot. MDA-MB-231and Hs 578Bst cells were treated with TGF-β1 and/or TGF-β1 receptor I kinase (Alk5) inhibitor SB431542, and the endogenous TMEPAI was detected. MDA-MB-231 cells were transfected by Smad7, Alk5 and dominant-negative TGF-β1 receptor I (DN Alk5) plasmids, and the changes of TMEPAI level were tested. TMEPAI in MDA-MB-231 cells was knockdowned and the expressions of phosphatase and tensin homologue (PTEN) and p27kip1 were detected. Results   TMEPAI overexpression was found in “triple-negative” breast cancer tissues and cell lines, but no expression of TMEPAI was found in normal breast tissues and MCF-7 cell lines.The diffenrence had statistical significance (P＜0.05). Conclusion   Activation of TGF-β1 signaling pathway in breast cancer cells led to the overexpression of TMEPAI, and TMEPAI promoted the development of breast cancer through influencing expressions of multiple tumour-related proteins.

Key words: Transforming growth factor-β1 (TGF-β1); Prostate transmembrane protein, androgen induced 1 (TMEPAI); Breast tumour; Signal transduction