Sirt7, a member of the sirutin family, is overexpressed in some cancers. In a study of the potential role of Sirt7 in colorectal cancer reported in Clinical Cancer Research, Yu and colleagues found that increased Sirt7 protein level in colorectal cancer tissue was associated with higher tumor stage (P = .029), lymph node metastasis (P = .046), and reduced survival (P < .05).
Sirt7 knockdown was associated with significant inhibition of colorectal cancer cell proliferation, colony formation, and motility, whereas ectopic Sirt7 expression promoted colony formation and a more invasive phenotype and accelerated cell growth in vitro and in vivo. Increased Sirt7 expression was associated with increased MAPK pathway activity and simultaneous upregulation of p-ERK and p-MEK. In cells overexpressing Sirt7, the mesenchymal markers vimentin and fibronectin were upregulated and the epithelial markers E-cadherin and beta-catenin were downregulated, with these alterations being associated with increased colorectal cancer cell invasiveness.
The investigators concluded, “Our findings suggest that Sirt7 plays an important role in the development and progression of human [colorectal cancer] and functions as a valuable marker of [colorectal cancer] prognosis.” ■
Yu H, et al: Clin Cancer Res 20:3434-3445, 2014.