J. Cancer Mol. 5: 55-62, 2010

[Research Paper]

Beta-Arrestin-1-Dependent Activation of Extracellular Signal-Regulated Kinases in RON Receptor-Mediated Tumorigenic Activities in Colon Cancer Cells

Yong-Qing Zhou, Yu-Lan Luo, Wendy Zhou, Hang-Ping Yao, and Ming-Hai Wang

Laboratory of Cancer Biology & Therapeutics and Division of Neurosurgery, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310003, P. R. China [Y.-Q. Zhou, H.-P. Yao, M.-H. Wang]; Cancer Biology Center and Department of Biomedical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA [Y.-L. Luo, W. Zhou, M.-H. Wang]

Abstract:

AIM: Beta-Arrestin-1 is an adaptor protein essential in G-protein-coupled receptor signaling and function.  Recently, a mechanism by which beta-arrestin-1 acted as a scaffolding molecule that regulated signaling pathways of receptor tyrosine kinases was discovered.  The goal of this study is to determine the roles of beta-arrestin-1 in RON-activated MAP kinase signaling that regulates tumorigenic activities of colon cancer cells.

METHODS: Immunohistochemistry of tumor tissue arrays was used to determine RON and beta-arrestin-1 expression.  Immunoprecipitation and Western blotting were used to determine protein interaction and phosphorylation.  Specific siRNA was used to silence beta-arrestin-1 gene expression.  Cell growth, transformation, and migration were determined by proliferation, focus formation and migration assays.

RESULTS: Overexpression of RON (52/88 cases, 59.1%) in primary colon cancer samples was significantly matched with beta-arrestin-1 expression.  In 52 samples with RON overexpression, beta-arrestin-1 was co-expressed in 41 cases (46.6%).  In colon cancer HT-29 and other cells, beta-arrestin-1 formed a signaling protein complex with RON and c-Src.  RON-mediated dephosphorylation of beta-arrestin-1 at Ser-412 increased their interaction.  Silencing of beta-arrestin-1 gene expression by siRNA techniques impaired RON-mediated Erk1/2 phosphorylation but had no effect on AKT phosphorylation.  The beta-arrestin-1 gene disruption also blocked oncogenic RON160-mediated cellular transformation in rodent fibroblast and colonic epithelial cells.  Moreover, silencing beta-arrestin-1 gene expression significantly reduced RON agonistic mAb Zt/c1-induced colon cancer cell proliferation but not migration.

CONCLUSION: Beta-Arrestin-1 was selectively involved in RON-transduced signals.  The requirement of beta-arrestin-1 in MAP kinase signaling shed light on the mechanisms by which RON regulated malignancy of colon cancer cells.

(Keywords: RON; RON160; beta-arrestin-1; signal transduction; tumorigenic phenotype)

Received 7/6/09; Revised 9/14/09; Accepted 9/24/09.

1. Correspondence: Dr. Yong-Qing Zhou, Division of Neurosurgery, First Affiliated Hospital, Zhejiang University School of Medicine, No. 79 Qing-Chun Road, Hangzhou, Zhejiang, 310003, P. R. China. E-mail: zhouyq56@hotmail.com; Dr. Ming-Hai Wang, Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA. Phone: 1-806-3564015 ext. 248. Fax: 1-806-3564034. E-mail: minghai.wang@ttuhsc.edu

2. Abbreviations: MAP, mitogen-activated protein kinase; Erk, extracellular signal-regulated kinase; RON, recepteur d’origine nantais; Sos, son of sevenless; Grb, growth factor receptor bound protein; mAb monoclonal antibody; siRNA, small interfering RNA; MSP, macrophage-stimulating protein; PI, phosphatidylinositol; Dvl, protein disheveled; PDGF, platelet-derived growth factor.

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