Up-regulation of Tiam1 and Rac1 correlates with poor prognosis in hepatocellular carcinoma

Abstract

Objective: T-cell lymphoma invasion and metastasis 1 (Tiam1) specifically activates Rho-like GTPases (e.g. Rac1) and Tiam1-Rac1 pathway affects the migration and invasion of many tumors, such as nasopharyngeal carcinoma, breast cancer and retinoblastoma. However, no studies have yet comprehensively examined the involvement of Tiam1-Rac1 pathway in hepatocellular carcinoma. In this study, we examined the relationship of the up-regulation of Tiam1 and Rac1 with clinicopathological features in patients with hepatocellular carcinoma. Methods: Expression of Tiam1 and Rac1 was assessed in 242 hepatocellular carcinoma tissues and their adjacent normal hepatic tissues by performing immunohistochemistry and was gauged regarding stage, grade and survival. Results: Immunohistochemistry showed that patients with a high clinical stage hepatocellular carcinoma (III-IV) and α-fetoprotein levels had a higher tendency to express Tiam1 and Rac1 on tumor cells than the patients with low pathologic grade hepatocellular carcinoma (I-II) (P = 0.008 and 0.01, respectively) and low α-fetoprotein levels (P = 0.006 and 0.002, respectively). In addition, Tiam1 and Rac1 up-regulation was also significantly associated with vascular invasion status (both P = 0.02), intrahepatic metastasis status (P = 0.009 and 0.01, respectively) and histological differentiation (P = 0.008 and 0.009, respectively) of patients with hepatocellular carcinoma. Moreover, post-operative survival analysis indicated that hepatocellular carcinoma patients with strong Tiam1 (P = 0.01) and Rac1 (P = 0.02) expression had shorter disease-specific survival than those with weak expression. Multivariate analysis also showed that Tiam1 and Rac1 overexpression could be two predictors of poor prognosis (P = 0.02 and 0.03, respectively). Conclusions: The current study demonstrated for the first time that the Tiam1-Rac1 pathway may play a critical role in tumor progression of hepatocellular carcinoma. The expression of Tiam1 and Rac1 can be considered as the two useful indicators for predicting the prognosis of hepatocellular carcinoma. © The Author (2010). Published by Oxford University Press. All rights reserved.