RICTOR expression in esophageal squamous cell carcinoma and its clinical significance.

Esophageal cancer is one of the most common malignant tumors in the world, and its incidence is the eighth highest; meanwhile, its fatality rate is the sixth highest. The PI3K/Akt/mTOR signaling pathway plays a required role in human cancer, including cell survival, metabolism and migration. As a kind of important scaffold protein in mTORC2, RICTOR has showed over-expression in several malignancies like melanoma and endometrial cancer. In this research, we selected 201 cases of paraffin specimens from patients diagnosed as esophageal squamous cell carcinoma after surgical treatment and then estimated the RICTOR expression in each esophageal squamous cell carcinoma tissue by using the immunohistochemical streptavidin-peroxidase technique. Then, we analyzed the association among the clinicopathological parameters, the prognosis and the expression of RICTOR. Eventually, we found that the percentage of RICTOR-positive expression in 201 ESCC samples is 70.6% (142/201) and the figure for RICTOR-negative or RICTOR-doubtful-positive expression is 29.4% (59/201). RICTOR expression positively correlated with ESCC patients' AJCC stage (P = 0.011) and showed an opposite trend with survival (P = 0.007). Based on univariate and multivariate Cox proportional hazards regression analysis, RICTOR-positive expression, AJCC staging III or IV and nodal metastasis are prognostic factors and the former two are independent risk factors for ESCC. In conclusion, our study showed potential that targeting RICTOR may represent new effective inhibitors for treating ESCC.