Over-expression of Sirt1 contributes to chemoresistance and indicates poor prognosis in serous epithelial ovarian cancer (EOC).

Ovarian cancer is the most lethal malignancy in female patients, and chemoresistance is the major contribution to low over survival rate. We aim to investigate the correction between Sirt1 expression and chemoresistance in serous epithelial ovarian cancer (EOC) and prognosis significance of Sirt1. Immunochemistry was used to determine the location pattern and expression of Sirt1 in a total of 63 serous EOC patients (28 cases of chemoresistance patients and 35 chemosensitive).The relationship between Sirt1 expression and clinicopathological features of serous EOC was analyzed. Univariate analysis and multifactor logistic regression analysis were applied to investigate risk factor for chemoresistance. Cox proportional hazards regression model and Kaplan-Meier survival analysis were applied to determine the prognosis factor and survival time. Immunohistochemistry proved that over-expression of nuclear Sirt1 was related to chemoresistance (P = 0.039). Multivariate logistic regression analysis proved that the nuclear expression of Sirt1 (P = 0.018) and the lymph node metastasis (P = 0.037) was independent risk factors for chemoresistance in serous epithelial ovarian cancer. Multivariate Cox regression result indicated that expression of Sirt1 (P = 0.026, RR 2.434, 95 % CI 1.109-5.339) and stage (P = 0.005, RR 2.366, 95 % CI 1.288-4.345) was independent prognostic factors. Kaplan-Meier analysis showed that the survival rate is significantly decreased in the Sirt1 highly expressed group. Western blot result showed that the protein level of Sirt1 was significantly higher in chemoresistant group compared with in sensitive group. In conclusion, our results proved that over-expression of Sirt1 could play an important role in chemoresistance of serous EOC and could be a prognosis indicator for the patient's survival outcome.