A novel mechanism of colon carcinoma cell adhesion to the endothelium triggered by beta 1 integrin chain.
We have found a monoclonal antibody, called BV7, that rapidly stimulated by 6-10-folds HT-29 colon carcinoma cell adhesion to resting human umbilical vein endothelial cells. This effect was directed to tumor cells and not to endothelial cells and was cell-specific. BV7 was also active on the HCCP-2998 but did not change adhesion to endothelial cells of other tumor cells (MG63 osteosarcoma, A375 melanoma, MHCC-1410 and Lovo colon carcinoma) even if, by flow cytometry, this monoclonal antibody could bind to them. Additionally, BV7 effect was substratum-specific, since it did not increase but rather blocked HT-29 adhesion to matrix proteins. Immunoprecipitation analysis and binding to specific transfectants revealed that BV7 recognizes beta 1-subunit of integrin receptors and antibody blocking experiments showed that alpha 2 beta 1 antibodies were able to counteract BV7 effect on HT-29 adhesion to endothelial cells. In contrast, antibodies directed to other integrins or endothelial adhesive receptors (E- and P-selectin, VCAM-1, ICAM-1, ICAM-2) were ineffective. Induction of HT-29 adhesion to endothelial cells by BV7 was Fc- and protein synthesis-independent but required metabolically active cells. The presence of physiological concentrations of divalent cations and of cytoskeletal integrity was not needed. Comparative studies with eight different prototypic beta 1 antibodies showed that five of them induced HT-29 adhesion to endothelial cells in a way unrelated to their ability to interfere with HT-29 adhesion to matrix proteins. Cross-blocking binding assays demonstrated that all the five antibodies recognized a topographically related epitope. Taken together these results provide evidence that beta 1 antibodies may trigger a novel pathway of HT-29 colon carcinoma adhesion to endothelial cells with different features in respect to other described mechanisms of tumor cell interaction with the endothelium.
Martìn-Padura
I
I
Laboratory of Vascular Biology, Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
Bazzoni
G
G
Zanetti
A
A
Bernasconi
S
S
Elices
M J
MJ
Mantovani
A
A
Dejana
E
E
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000276:immunology; D002448:Cell Adhesion; D002478:Cells, Cultured; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D004730:Endothelium, Vascular / Q000166:cytology* / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D006801:Humans; D019012:Integrin beta1; D016023:Integrins / Q000276:immunology / Q000378:metabolism*; D008969:Molecular Sequence Data; D011956:Receptors, Cell Surface / Q000378:metabolism; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D016326:Extracellular Matrix Proteins; D019012:Integrin beta1; D016023:Integrins; D011956:Receptors, Cell Surface