Attachment, spreading and migration of melanoma cells on vitronectin

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Abstract
Recent in situ studies suggest the αvβ3 integrin is a tumour progression marker in melanoma. We analyzed 5 human melanoma cell lines for their expression of the vitronectin binding αvβ3 and αvβ5, integrins using flow cytometry. The role of these receptors in cell attachment, spreading and migration was investigated using attachment assays, video time lapse spreading and migration assays and with function blocking monoclonal antibodies. Cell lines derived from later stages of tumor progression exhibited high levels of αvβ3 expression, whereas no similar correlation with αvβ5 expression was identified. Cell attachment, spreading and migration response on vitronectin correlated well with the expression level of the αvβ3 but not the αvβ5 vitronectin receptor. Blocking of the αvβ3 integrin resulted in a significant decrease in cell attachment, spreading and motility whereas the function blocking antibody against the αvβ5 integrin only inhibited cell attachment in cell lines with the highest level of expression of this integrin. Taken together, our study indicates that the level of expression of the αvβ3 and αvβ5 integrins is heterogeneous in melanoma cell lines and that the αvβ5 integrin, if present, may function only during the initial cell attachment whereas the αvβ3 plays an important rôle in cell spreading and cell migration as well.