SIRT1 and the Clock Gene Machinery in Colorectal Cancer

SIRT1 and the clock genes are involved in carcinogenesis. We evaluated SIRT1 expression in 19 human colorectal cancer (CRC) specimens and clock gene expression in SIRT1-overexpressing CaCo2 and SW480 cells. In CRC, SIRT1 mean expression level was decreased. Compared to CaCo2 cells, SW480 cells displayed lower levels of SIRT1 and PER3 and higher levels of ARNTL1, CLOCK, PER1, PER2, CRY1, TIPIN, and CSNKIE. SIRT1 overexpression induced PER1 upregulation in CaCo2 and downregulation in SW480 cells. SIRT1 expression was heterogeneous in human CRC and in CRC cell lines. These results might have relevant implications for a better understanding of colorectal carcinogenesis.