Transfection of beta 4 integrin subunit into a neoplastic keratinocyte line fails to restore terminal differentiation capacity or influence proliferation.

Abstract

Loss of expression of specific integrins is a feature of poorly differentiated oral squamous cell carcinomas (SCCs) and cell lines derived from them. In order to test whether there is a direct link between reduced alpha 6 beta 4 integrin expression and abnormal keratinocyte growth and differentiation we 'repaired' an SCC line. H376, by transfection of the beta 4 integrin subunit. We analysed five independent beta 4 transfectant clones and compared them with four empty vector control clones and with the parental cell line. Elevated cell surface expression of alpha 6 beta 4 was not correlated with changes in anchorage dependent or independent growth and was not sufficient to induce expression of the terminal differentiation marker, involucrin. Introduction of the beta 4 integrin subunit did not have a major effect on cell adhesion to laminin 1 or 5 and did not result in formation of stable anchoring contacts. We conclude that loss of alpha 6 beta 4 is not directly responsible for the abnormal behaviour of the H376 cell line.