Expression of RhoA in Colorectal Cancers and Its Clinicopathological Significance

ABSTRACT

PURPOSE: The Rho family of GTPases are involved in actin cytoskeleton organization and are associated with carcinogenesis and progression of human cancers. The clinicopathological significance of RhoA is not yet well known in the case of colorectal cancer. To investigate the expression of RhoA protein in colorectal carcinoma and to evaluate the relationship between RhoA protein expression and invasion and metastasis of colorectal cancer, we examined the expression of RhoA protein by using Western blotting and immunohistochemistry. METHODS: The protein levels of RhoA in colorectal carcinomas of surgical specimens were analyzed in 71 consecutive patients with colorectal cancers by using immunohistochemistry and Western blotting. The relationships between the protein levels of RhoA in tumor tissues and the clinicopathological features of the patients were also assessed. RESULTS: RhoA was highly expressed in 48 colorectal carcinomas (67.6%). There was a significant association between RhoA expression and lymph nodal status. The expression of RhoA protein was related to lymph-node metastasis (P=0.032) and advanced TNM tumor staging (P=0.020). RhoA expression had a significant prognostic value for overall survival. Kaplan-Meier plots of survival in patients with high RhoA showed that high RhoA expression was associated with a shorter overall survival. However, no association was found between RhoA and other pathologic or clinical variables, including age, gender, degree of differentiation, and presence of perineural spread. CONCLUSIONS: The RhoA protein may be related to malignant transformation and development of colorectal caricinomas and may play an important role in the invasion and the metastasis of colorectal carcinomas.