A region in urokinase plasminogen receptor domain III controlling a functional association with alpha5beta1 integrin and tumor growth

TY - JOUR

T1 - A region in urokinase plasminogen receptor domain III controlling a functional association with alpha5beta1 integrin and tumor growth

AU - Chaurasia, Pratima

AU - Aguirre-Ghiso, Julio

AU - Liang, Olin D

AU - Gardsvoll, Henrik

AU - Ploug, Michael

AU - Ossowski, Liliana

PY - 2006/5/26

Y1 - 2006/5/26

N2 - Highly expressed urokinase plasminogen activator receptor (uPAR) can interact with alpha5beta1 integrin leading to persistent ERK activation and tumorigenicity. Disrupting this interaction reduces ERK activity, forcing cancer cells into dormancy. We identified a site in uPAR domain III that is indispensable for these effects. A 9-mer peptide derived from a sequence in domain III (residues 240-248) binds purified alpha5beta1 integrin. Substituting a single amino acid (S245A) in this peptide, or in full-length soluble uPAR, impairs binding of the purified integrin. In the recently solved crystal structure of uPAR the Ser-245 is confined to the large external surface of the receptor, a location that is well separated from the central urokinase plasminogen binding cavity. The impact of this site on alpha5beta1 integrin-dependent cell functions was examined by comparing cells induced to express uPAR(wt) or the uPAR(S245A) mutant. Transfecting uPAR(wt) into cells with low endogenous levels of uPAR, inactive integrin, low ERK activity, and a dormant phenotype in vivo restores these functions and reinstates growth in vivo. In contrast, transfection of the same cells with uPAR(S245A) elicits only very small changes. Incubation of highly malignant cells with the wild-type, but not the S245A mutant peptide, disrupts the uPAR integrin interaction leading to down-regulation of ERK activity. The relevance of this binding site, and of the lateral uPAR-alpha5beta1 integrin interaction, to ERK pathway activation and tumor growth implicates it as a possible specific target for cancer therapy.

AB - Highly expressed urokinase plasminogen activator receptor (uPAR) can interact with alpha5beta1 integrin leading to persistent ERK activation and tumorigenicity. Disrupting this interaction reduces ERK activity, forcing cancer cells into dormancy. We identified a site in uPAR domain III that is indispensable for these effects. A 9-mer peptide derived from a sequence in domain III (residues 240-248) binds purified alpha5beta1 integrin. Substituting a single amino acid (S245A) in this peptide, or in full-length soluble uPAR, impairs binding of the purified integrin. In the recently solved crystal structure of uPAR the Ser-245 is confined to the large external surface of the receptor, a location that is well separated from the central urokinase plasminogen binding cavity. The impact of this site on alpha5beta1 integrin-dependent cell functions was examined by comparing cells induced to express uPAR(wt) or the uPAR(S245A) mutant. Transfecting uPAR(wt) into cells with low endogenous levels of uPAR, inactive integrin, low ERK activity, and a dormant phenotype in vivo restores these functions and reinstates growth in vivo. In contrast, transfection of the same cells with uPAR(S245A) elicits only very small changes. Incubation of highly malignant cells with the wild-type, but not the S245A mutant peptide, disrupts the uPAR integrin interaction leading to down-regulation of ERK activity. The relevance of this binding site, and of the lateral uPAR-alpha5beta1 integrin interaction, to ERK pathway activation and tumor growth implicates it as a possible specific target for cancer therapy.

KW - Alanine

KW - Biotinylation

KW - Cell Line, Tumor

KW - Crystallography, X-Ray

KW - Humans

KW - Integrin alpha5beta1

KW - Models, Molecular

KW - Neoplasms

KW - Peptides

KW - Protein Structure, Tertiary

KW - Receptors, Cell Surface

KW - Receptors, Urokinase Plasminogen Activator

KW - Serine

KW - Signal Transduction

KW - Journal Article

KW - Research Support, N.I.H., Extramural

KW - Research Support, Non-U.S. Gov't

U2 - 10.1074/jbc.M512311200

DO - 10.1074/jbc.M512311200

M3 - Journal article

C2 - 16547007

SN - 0021-9258

VL - 281

SP - 14852

EP - 14863

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

IS - 21

ER -