Expression and role of SIRT1 in hepatocellular carcinoma.

Silent mating type information regulation 2 homolog 1 (SIRT1) is a multifaceted, nicotinamide adenine dinucleotide-dependent protein deacetylase with involvement in a wide variety of cellular processes ranging from cancer to aging. Expression of SIRT1 was evaluated in 90 cases of hepatocellular carcinoma (HCC) and five HCC cell lines. The relationship between the mutation status of p53 and expression of SIRT1 was also investigated in 10 fresh HCC tissues. Synthetic small interfering RNA was used to silence SIRT1 gene expression by RNA interference (RNAi), and cell growth and cell cycle progression were assessed. Expression of SIRT1 was significantly elevated in the HCC tissues when compared to that of non-tumor tissues (p<0.001). Overexpression of SIRT1 and p53 was observed in 56% (50 of 90) and in 30% (27 of 90) of the HCCs, respectively. Expression of SIRT1 showed significant correlation with gender (p=0.023), serum AFP levels (p=0.030), viral infection (p=0.005) and p53 expression (p<0.021). Western blot analysis found no correlation between p53 mutation and expression levels of SIRT1. SIRT1 silencing was found to induce cell growth arrest in HCC cells. These results suggest an association of SIRT1 expression with HCC development and that SIRT1 plays a role in cancer cell growth.