REGULATION OF VITRONECTIN RECEPTOR EXPRESSION BY RETINOIC ACID ON HUMAN-MELANOMA CELLS

The integrin family of adhesion receptors is likely to be important fo r tumor cell invasion and dissemination. We have studied the effects o f the differentiating agents retinoic acid on integrin expression by t he human melanoma cell line MeWo. Our results show that this agent inh ibits cellular proliferation, increases melanin content and induces mo rphological changes in MeWo cells. Functionally, these alterations are associated with an enhanced adhesion to matrix protein vitronectin an d higher levels of expression of vitronectin receptor on the cell surf ace. This is accompanied by increased levels of a, integrin mRNA. Alth ough the mechanism by which retinoic acid regulates the expression of vitronectin receptor in MeWo cells needs further examination, this sys tem may represent a good model for understanding the role of this rece ptor in melanoma progression, as well the molecular basis for retinoic acid therapy in these tumors.