SIRT1 expression is associated with poor prognosis of diffuse large B-cell lymphoma

Sirtuin1 (SIRT1) is a nicotinamide adenine dinucleotide-dependent deacetylase. Recently, it is suggested that SIRT1 may be involved in the development of malignant tumors including mouse lymphoma. Therefore, we investigated the prevalence and the prognostic impact of SIRTI expression in diffuse large B-cell lymphoma (DLBCL). Immunohistochemical expression of SIRT1, p53, bcl2, CD10, bcl6, and multiple myeloma-1 (MUM1) were evaluated by using a 2mm core from 104 DLBCL patients for tissue microarray. Positive expression of SIRTI was seen in 74% (77/104) of patients. In total DLBCL patients, SIRTI and p53 expression were significantly associated with shorter overall survival (OS) by univariate analysis (P = 0.001 and P = 0.011, respectively). SIRTI was also an independent prognostic factor by multivariate analysis (P = 0.01). According to the expression patterns of CD 10, bcl6, and MUM 1, germinal center B cell (GCB) types were represented in 38 cases (37%,) and non-GCB types were represented in 66 cases (63%). In the GCB type, only p53 expression was associated with a significantly shorter OS (P = 0.032). In the non-GCB type, expression of SIRTI correlated with shorter OS by univariate analyses (P = 0.005) and multivariate analyses (P = 0.049). In conclusion, we showed that SIRTI expression is a clinically significant prognostic indicator for DLBCL patients.