Rho kinase phosphorylation promotes ezrin-mediated metastasis in hepatocellular carcinoma.

Abstract

During progression of hepatocellular carcinoma, multiple genetic and epigenetic alterations act to posttranslationally modulate the function of proteins that promote cancer invasion and metastasis. To define such abnormalities that contribute to liver cancer metastasis, we carried out a proteomic comparison of primary hepatocellular carcinoma and samples of intravascular thrombi from the same patient. Mass spectrometric analyses of the liver cancer samples revealed a series of acidic phospho-isotypes associated with the intravascular thrombi samples. In particular, we found that Thr567 hyperphosphorylation of the cytoskeletal protein ezrin was tightly correlated to an invasive phenotype of clinical hepatocellular carcinomas and to poor outcomes in tumor xenograft assays. Using phospho-mimicking mutants, we showed that ezrin phosphorylation at Thr567 promoted in vitro invasion by hepatocarcinoma cells. Phospho-mimicking mutant ezrinT567D, but not the nonphosphorylatable mutant ezrinT567A, stimulated formation of membrane ruffles, suggesting that Thr567 phosphorylation promotes cytoskeletal-membrane remodeling. Importantly, inhibition of Rho kinase, either by Y27632 or RNA interference, resulted in inhibition of Thr567 phosphorylation and a blockade to cell invasion, implicating Rho kinase-ezrin signaling in hepatocellular carcinoma cell invasion. Our findings suggest a strategy to reduce liver tumor metastasis by blocking Rho kinase-mediated phosphorylation of ezrin.

• Authors: Yong Chen, Dongmei Wang, Zhen Guo, Jun Zhao, Bing Wu, Hui Deng, Ti Zhou, Hongjun Xiang, Fei Gao, Xue Yu, Jian Liao, Tarsha Ward, Peng Xia, Chibuzo Emenari, Xia Ding, Winston Thompson, Kelong Ma, Jingde Zhu, Felix Aikhionbare, Kefen Dou, Shi-Yuan Cheng, Xuebiao Yao
• Journal: Cancer research (Cancer Res) Vol. 71 Issue 5 Pg. 1721-9 (Mar 01 2011) ISSN: 1538-7445 [Electronic] United States
• PMID: 21363921 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: ©2011 AACR.

Chemical References

• Cytoskeletal Proteins
• Enzyme Inhibitors
• ezrin
• rho-Associated Kinases

Topics

• Animals
• Blotting, Western
• Carcinoma, Hepatocellular (metabolism, pathology)
• Cytoskeletal Proteins (metabolism)
• Enzyme Inhibitors (pharmacology)
• Female
• Humans
• Immunohistochemistry
• Liver Neoplasms (metabolism, pathology)
• Mice
• Mice, SCID
• Neoplasm Invasiveness
• Neoplasm Metastasis
• Phosphorylation
• Signal Transduction (physiology)
• Xenograft Model Antitumor Assays
• rho-Associated Kinases (metabolism)