The expression and correlation of SIRT1 and Phospho-SIRT1 in colorectal cancer.

SIRT1 is the homologue of sir2 in mammals, which is a nicotinamide adenine dinucleotide (NAD(+)) dependent histone deacetylase. SIRT1 is involved in many physiological processes, such as metabolism, senescence, inflammatory response, neuroprotection, and tumorigenesis by acetylating histones and multiple transcription factors. However, the exact role of SIRT1 in tumor is still under controversial. Immunohistochemistry and Western blot were performed to investigate the expressions and subcellular localizations of SIRT1 and Phospho-SIRT1 in colorectal cancer tissues and adjacent normal tissues. The relationship between SIRT1 or Phospho-SIRT1 and clinicopathological characteristics was also analyzed. Real-Time PCR was performed to investigate the transcriptional level of SIRT1 mRNA in colorectal cancer tissues and adjacent normal tissues. SIRT1 and Phospho-SIRT1 were both localized in the nucleus. The expressions of SIRT1 and Phospho-SIRT1 were higher in colorectal cancer tissues than normal tissues. SIRT1 expression in cancer tissues was associated with patient age, TNM stage and mutant P53 loss. Phospho-SIRT1 expression in cancer tissues was associated with Ki67. SIRT1 and Phospho-SIRT1 were highly correlated in cancer tissues and normal tissues. The ratios of Phospho-SIRT1 and SIRT1 expression in cancer tissues were higher than normal tissues. SIRT1 mRNA level was no significant difference in cancer tissues and normal tissues. SIRT1 have a dual character in colorectal cancer, and Phospho-SIRT1 may determine the role of SIRT1 in colorectal cancer formation.