Human cervical tumor cell (SiHa) surface alphavbeta3 integrin receptor has associated matrix metalloproteinase (MMP-2) activity.
OBJECTIVE
Integrins are transmembrane heterodimeric molecules that mediate cellular adhesion and are involved in different biological processes, such as tumor development and invasion of tumor cells. Matrixmetalloproteases (MMP) are a family of secreted or membrane proteins capable of digesting extracellular matrix. It has been shown that MMP-2 binds to alphavbeta3 integrin. Recent evidence suggests that a complex of membrane-type MMP (MT1-MMP) and tissue inhibitor of metalloptroteinase-2 (TIMP-2) participate in the activation of alphavbeta3-associated MMP-2. We investigated whether alphavbeta3 and MMP-2 are associated on the membranes of a human cell line, SiHa, and the possible involvement of MT1-MMP and TIMP-2 in the modulation of MMP-2 activity.


METHODS
Immunoprecipitation of SiHa membrane extracts with monoclonal antibodies against alphav or MMP-2, and western blots of immunoprecipitates and serum-free conditioned media were performed. TIMP-2 in conditioned medium and MT1-MMP in the membrane fraction was assayed by western blot. Zymography of anti-alphav antibody immunoprecipitates and conditioned media were used to show gelatinolytic activity.


RESULTS
The coprecipitation of MMP-2 with alphavbeta3 by anti-alphav antibody is a strong indication that SiHa cell surface alphavbeta3 integrin is a receptor for MMP-2. Immunoblot assays show the expression of MT1-MMP on SiHa cell membranes and secreted TIMP-2 and pro-MMP-2 in the medium.


CONCLUSIONS
SiHa cells express all the molecules which are reported to form a complex to activate pro-MMP-2. Active MMP-2 associated with alphavbeta3 may regulate matrix degradation and thereby modulate directed motility of SiHa cells.
Chattopadhyay
N
N
Department of Receptor Biology and Tumor Metastasis, Chittaranjan National Cancer Institute, Calcutta, India.
Mitra
A
A
Frei
E
E
Chatterjee
A
A
D019921:Biotinylation; D015153:Blotting, Western; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism*; D019281:Dimerization; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D018093:Gelatinases / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D020781:Matrix Metalloproteinase 1 / Q000378:metabolism; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D011233:Precipitin Tests; D019030:Receptors, Vitronectin / Q000096:biosynthesis*; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism; D014407:Tumor Cells, Cultured; D002583:Uterine Cervical Neoplasms / Q000378:metabolism*
D019030:Receptors, Vitronectin; D019716:Tissue Inhibitor of Metalloproteinase-2; D018093:Gelatinases; D020778:Matrix Metalloproteinase 2; D020781:Matrix Metalloproteinase 1