Integrin-linked Protein Kinase Regulates Fibronectin Matrix Assembly, E-cadherin Expression, and Tumorigenicity

doi:10.1074/jbc.273.1.528

Integrin-linked Protein Kinase Regulates Fibronectin Matrix Assembly, E-cadherin Expression, and Tumorigenicity*

From the ^‡Samuel C. Johnson Medical Research Center, Mayo Clinic Scottsdale, Scottsdale, Arizona 85259, the ^‖Cancer Biology Research Program, Sunnybrook Health Science Centre, and Department of Medical Biophysics, University of Toronto, Toronto M4N 3M5, Ontario, Canada, and the ^§Department of Cell Biology and The Cell Adhesion and Matrix Research Center, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019

Abstract

Fibronectin (Fn) matrix plays important roles in many biological processes including morphogenesis and tumorigenesis. Recent studies have demonstrated a critical role of integrin cytoplasmic domains in regulating Fn matrix assembly, implying that intracellular integrin-binding proteins may be involved in controlling extracellular Fn matrix assembly. We report here that overexpression of integrin-linked kinase (ILK), a newly identified serine/threonine kinase that binds to the integrin β₁ cytoplasmic domain, dramatically stimulated Fn matrix assembly in epithelial cells. The integrin-linked kinase activity is involved in transducing signals leading to the up-regulation of Fn matrix assembly, as overexpression of a kinase-inactive ILK mutant failed to enhance the matrix assembly. Moreover, the increase in Fn matrix assembly induced by ILK overexpression was accompanied by a substantial reduction in the cellular E-cadherin. Finally, we show that ILK-overexpressing epithelial cells readily formed tumors in nude mice, despite forming an extensive Fn matrix. These results identify ILK as an important regulator of pericellular Fn matrix assembly, and suggest a novel critical role of this integrin-linked kinase in cell growth, cell survival, and tumorigenesis.

Footnotes

↵* This work was supported in part by grants from the American Heart Association (to C. W.), the American Lung Association (to C. W.), the Arizona Disease Control Research Commission (to C. W. and J. A. M), and the National Cancer Institute of Canada (to S. D.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¶ Edward Livingston Trudeau Scholar of the American Lung Association and Parker B. Francis Fellow in Pulmonary Research. To whom correspondence should be addressed: Dept. of Cell Biology and The Cell Adhesion and Matrix Research Center, University of Alabama at Birmingham, Birmingham, AL 35294-0019. Tel.: 205-975-2253; Fax: 205-934-7029; E-mail: cwu{at}bmg.bhs.uab.edu.
↵** Terry Fox Scientist of the National Cancer Institute of Canada.
↵1 The abbreviations used are: Fn, fibronectin; ILK, integrin-linked kinase; CHO, Chinese hamster ovary; FBS, fetal bovine serum; α-MEM, α-minimal essential medium; MT, metallothionein promoter; TBS, Tris-buffered saline; BSA, bovine serum albumin; PBS, phosphate-buffered saline; ELISA, enzyme-linked immunosorbent assay; FAK, focal adhesion kinase; AEBSF, [4-(2-aminoethyl)benzenesulfonylfluoride, HCl].
↵2 A. Novak, S. Hsu, C. Leung-Hagesteijn, G. Radeva, J. Papkoff, R. Montesano, C. Roskelley, R. Grosschedl, and S. Dedhar, submitted for publication.
↵3 C. Wu, S. Y. Keightley, C. Leung-Hagesteijn, G. Radeva, M. Coppolino, S. Goicoechea, J. A. McDonald, and S. Dedhar, unpublished observations.
- Received December 9, 1996.
- Revision received September 2, 1997.
The American Society for Biochemistry and Molecular Biology, Inc.