Clinical Significance of mTOR and p-mTOR Protein Expression in Human Colorectal Carcinoma

Colorectal carcinoma is the third most common type of malignant tumor in the world. Despite great advances in modern therapeutic strategies, overall survival of patients undergoing complete resection of carcinomas is short (Otake et al., 2010). Knowledge of molecular biomarkers associated with the prognosis of colorectal carcinomas may help to devise new treatment strategies and improve clinical outcome. A potential candidate of biomarkers for colorectal carcinomas is the mammalian target of rapamycin (mTOR), a Ser/Thr protein kinase which plays a key role in regulating important cellular functions, including proliferation (Buck et al., 2006), growth (Shaw and Cantley, 2006), survival (Foster, 2009), mobility and angiogenesis (Jiang and Liu, 2008). In several noncolorectal tumors, activation of the mTOR pathway and overexpression correlate with more aggressive clinical courses, and has been reported to be useful target therapy (Raymond et al., 2004; O’Donnell et al., 2008; Rizell et al., 2008). The aim of the present study was to examine the expression of mTOR and p-mTOR in colon carcinomas and its correlation to clinicopathological characteristics.