Characterization of zinc-alpha(2)-glycoprotein as a cell adhesion molecule that inhibits the proliferation of an oral tumor cell line.
Zn-alpha(2)-glycoprotein (Znalpha(2)gp) is a soluble protein widely distributed in body fluids and glandular epithelia. We have found it to be expressed in stratified epithelia as well. Znalpha(2)gp is clinically correlated with differentiation in various epithelial tumors, including oral and epidermal tumors. We have cloned epidermal Znalpha(2)gp and report the preparation of the recombinant protein in a Baculovirus expression system. Like the native molecule, recombinant Znalpha(2)gp has RNase activity. Znalpha(2)gp functions as a matrix protein for the Tu-138 oral squamous cell carcinoma cell line. Cell attachment to Znalpha(2)gp is comparable to that for fibronectin and is inhibited by the synthetic RGD peptides RGD, RGDV, and RGDS. Attachment is also inhibited by the antibody to integrin alpha(5)beta(1) (the fibronectin receptor), but not by antibodies to integrins alpha(v)beta(3), alpha(3)beta(1), and alpha(2)beta(1). We find that the proliferation of Tu-138 cells is inhibited on a Znalpha(2)gp matrix, as compared with other matrix proteins (fibronectin, vitronectin, laminin, and collagens I and IV) on which growth resembles that on the BSA control. We believe that the role of Znalpha(2)gp in differentiation and its RNase activity are two likely suspects as agents of the inhibition of proliferation.
Lei
G
G
Department of Dermatology, University of Texas Medical Branch, Galveston, Texas 77555, USA.
Brysk
H
H
Arany
I
I
Tyring
S K
SK
Srinivasan
G
G
Brysk
M M
MM
D000906:Antibodies / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D015815:Cell Adhesion Molecules / Q000378:metabolism* / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects*; D003001:Cloning, Molecular; D016326:Extracellular Matrix Proteins / Q000378:metabolism / Q000494:pharmacology; D005887:Gingival Neoplasms; D006023:Glycoproteins / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D016023:Integrins / Q000276:immunology / Q000378:metabolism; D008858:Microscopy, Phase-Contrast; D009842:Oligopeptides / Q000737:chemistry / Q000494:pharmacology; D011994:Recombinant Proteins / Q000378:metabolism; D029589:Seminal Plasma Proteins; D014407:Tumor Cells, Cultured; D000090203:Zn-Alpha-2-Glycoprotein
D000906:Antibodies; D015815:Cell Adhesion Molecules; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D016023:Integrins; D009842:Oligopeptides; D011994:Recombinant Proteins; D029589:Seminal Plasma Proteins; D000090203:Zn-Alpha-2-Glycoprotein; C047981:arginyl-glycyl-aspartic acid