High expression of Sirt7 served as a predictor of adverse outcome in breast cancer.

OBJECTIVE Sirt7, as one of the seven Sirtuin family members, which plays distinct roles in cancer progression, is bringing emerging attention due to its oncogenic characteristic. The expression of Sirt7 in breast cancer remained unclear, and the aim of this study was to elucidate its role in breast cancer. METHODS A total of 188 cases included in this study were immunohistochemically evaluated for Sirt7, and western blot assay was used to assess its expression in breast cell lines as well as 36 breast cancer tissues and 36 paired non-cancerous tissues. RESULTS Upregulation of Sirt7 was found in breast cancer cell lines and breast cancer tissues (P < 0.001) by western blot analysis. Sirt7 was highly expressed in breast cancer tissue samples (67.8%) compared to adjacent normal breast tissues (31.8%) by immunohistochemical assay. It was also observed that the high expression level of Sirt7 was significantly correlated with high histological grade (P = 0.039) and negatively related to overall survival (P = 0.006). Sirt7 proved to be an independent prognostic factor (P = 0.007) in breast cancer. CONCLUSIONS Sirt7 expression was implicated with high histological grade and independently predicted poor clinical outcome in patients with breast cancer, suggesting that Sirt7 might play a role in the malignant progression of breast cancer.