RESEARCH COMMUNICATION ER81-shRNA Inhibits Growth of Triple-negative Human Breast Cancer Cell Line MDA-MB-231 In Vivo and in Vitro

Previous studies have shown that ETS-related protein 81 (ER81), a downstream gene of Human epidermal growth factor receptor 2 (HER2), may form a fusion protein with other proteins after chromosome translocation, leading to tumor formation, such as the fusion with the EWS gene and subsequent induction of Ewing’s sarcoma (Jeon et al., 1995; Janknecht, 2005). Some research data from several groups have demonstrated that ER81 overexpressed in breast cancer cell lines, breast cancer, prostatic carcinoma (Monte et al., 1995; Cai et al., 2007) teratocarcinoma (Monte et al., 1995) megakaryocytic leukemia (Monte et al., 1995) melanoma (Monte et al., 1995; Jane-Valbuena et al., 2010) and gastrointestinal stromal tumor (Chi et al., 2010). Transduction of the ER81 gene can induce prostatic intraepithelial neoplasms and spermatocystic hyperplasia in transgenic mice, finally leading to prostatic carcinoma and adenocarcinoma of the seminal vesicles (Tomlins et al., 2007; Shin et al., 2009). Data showed ER81 expressed weakly in normal breast ductal epithelium and hyperplastic epithelium without atypia, but high expression were detected immunohistochemically in atypical hyperplasia of mammary glands, ductal carcinoma in situ, and infiltrating breast cancer tissues (Wang et al., 2011). Together with previous results, we assumed ER81 expression was related to the incidence and progression of