Requirement of Receptor-bound Urokinase-type Plasminogen Activator for Integrin αvβ5-directed Cell Migration

doi:10.1074/jbc.271.46.29393

Requirement of Receptor-bound Urokinase-type Plasminogen Activator for Integrin αvβ5-directed Cell Migration*

From ^‡ The Scripps Research Institute, Departments of Immunology and Vascular Biology, IMM24, La Jolla, California 92037 and
^¶ Chiron Corporation, Emeryville, California 94608

**Recipient of a Faculty Research Award. To whom correspondence should be addressed:
Departments of Immunology and Vascular Biology, The Scripps Research Institute, IMM24 10666 N. Torrey Pines Rd., La Jolla, CA 92037
. Tel.: 619-554-8281; Fax: 619-554-8926.

Abstract

The urokinase plasminogen activator (uPA) interacts with its cell surface receptor (uPAR), providing an inducible, localized cell surface proteolytic activity, thereby promoting cellular invasion. Evidence is provided for a novel function of cell surface-associated uPA·uPAR. Specifically, induction of cell surface expression of uPA·uPAR by growth factors or phorbol ester was necessary for vitronectin-dependent carcinoma cell migration, an event mediated by integrin αvβ5. Cell migration on vitronectin was blocked with either a soluble form of uPAR, an antibody that disrupts uPA binding to uPAR, or a monoclonal antibody to αvβ5. Moreover, plasminogen activator inhibitor type 2 blocked this migration event but did not affect adhesion, suggesting a direct role for uPA enzyme activity in this process and that migration but not adhesion of these cells is regulated by uPA·uPAR. Growth factor-mediated induction of uPA·uPAR on the carcinoma cell surface promotes a specific motility event mediated by integrin αvβ5, since cells transfected with the β3 integrin subunit expressed αvβ3 and migrated on vitronectin independently of growth factors or uPA·uPAR expression. This relationship between αvβ5 and the uPA·uPAR system has significant implications for regulation of motility events associated with development, angiogenesis, and tumor metastasis.

Footnotes

↵^§ Supported by postdoctoral fellowships from The Swedish Cancer Society and Wenner-Gren Foundation.
↵^∥ Recipient of a Junior Faculty Research Award from the American Cancer Society.
↵^‡ Supported by NIH Training Grant T32-AI-07244.
↵* This work is supported by National Institutes of Health (NIH) Grants CA-45726, CA-50286, and HL54444 (to D. A. C.), CA59692 (to B. M. M.), and HL16411 (to N. M.). This is manuscript number 9926-IMM from the Scripps Research Institute. 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.
↵¹ The abbreviations used are:

uPA

urokinase-type plasminogen activator

uPAR

urokinase-type plasminogen activator receptor

TGF-α

transforming growth factor-α

PMA

phorbol 12-myristate 13-acetate

PAI-1 and PAI-2

plasminogen activator inhibitor-1 and −2

BSA

bovine serum albumin

FBM

fibroblast basal medium

FACS

fluorescence-activated cell-sorting

mAb

monoclonal antibody.
↵²M. Yebra, G. C. N. Parry, S. Strömblad, N. Mackman, S. Rosenberg, B. M. Mueller, and D. A. Cheresh, unpublished observations.
- Received April 27, 1996.
- Revision received August 30, 1996.