The
calcium-activated chloride channel Ano1 (TMEM16A) is overexpressed in many
tumors. Although Ano1 overexpression is found in
breast cancer due to 11q13 amplification, it remains unclear whether signaling pathways are involved in Ano1 overexpression during
breast cancer tumorigenesis in vivo.
Estrogen receptor (ER),
progesterone receptor (PR), and
human epidermal growth factor receptor 2 (HER2) have been known to contribute to
breast cancer progression. It is unclear whether Ano1 is associated with clinical outcomes in
breast cancer patients with different ER, PR and HER2 status. In the present study, we investigated the Ano1 expression in 431 patients with invasive ductal
breast carcinoma and 46 patients with
fibroadenoma, using immunohistochemistry, and analyzed the association between Ano1 expression and clinical characteristics and outcomes of
breast cancer patients with different ER, PR, and HER2 status. Ano1 was overexpressed in
breast cancer compared with
fibroadenoma. Ano1 was significantly more associated with
breast cancer with the lower clinical stage (stage I or II), or triple-negative status. Mostly importantly, Ano1 overexpression was associated with good prognosis in patients with the PR-positive or HER2-negative status, and in patients following
tamoxifen treatment. Multivariate Cox regression analysis showed that Ano1 overexpression was a prognostic factor for longer overall survival in PR-positive or HER2-negative patients, and a predictive factor for longer overall survival in patients following
tamoxifen treatment. Our findings suggest that Ano1 may be a potential marker for good prognosis in PR-positive or HER2-negative patients following
tamoxifen treatment. The PR and HER2 status defines a subtype of
breast cancer in which Ano1 overexpression is associated with good prognosis following
tamoxifen treatment.