Expression and prognostic significance of SIRT1 in ovarian epithelial tumours

Aims: Sirtuin1 (SIRT1) is a nicotinamide adenine dinucleotide-dependent deacetylase. Recently, some studies have suggested that SIRT1 could be over-expressed in breast, prostate and colon cancers and up-regulated SIRT1 inactivates p53 by deacetylation. Therefore, we investigated the prevalence and the prognostic impact of SIRT1 and p53 expression in ovarian epithelial tumours. Methods: Immunohistochemical expression of SIRT1 and p53 were evaluated using tissue microarray in 40 cases of benign epithelial tumours, 36 cases of borderline tumours, and 90 cases of malignant tumours. Results: Expression of SIRT1 was significantly increased in malignant epithelial tumours compared to benign and borderline epithelial tumours (p0.001). In particular, a high proportion of serous carcinoma expressed SIRT1 (86%, 55/64 cases). Despite the frequent expression of SIRT1 in malignant ovarian epithelial tumours, serous carcinomas of high FIGO stage showed less frequent SIRT1 expression compared to that of low stage serous carcinomas (p=0.029). Moreover, increased expression of SIRT1 in serous carcinoma correlated with increased overall survival by univariate (p=0.014) and multivariate analyses. Conclusions: Over-expression of SIRT1 may play an important role in the early stage of ovarian carcinogenesis.