Switch from αvβ5 to αvβ6 integrin expression protects squamous cell carcinomas from anoikis

Stratified squamous epithelia express the alphavbeta5 integrin, but in squamous cell carcinomas (SCCs) there is down-regulation of alphavbeta5 and up-regulation of alphavbeta6. To investigate the significance of this finding, we transduced an alphav-negative human SCC line with retroviral vectors encoding alphav integrins. alphavbeta5-expressing cells underwent suspension-induced apoptosis (anoikis), whereas alpha-negative cells and cells expressing alphavbeta6 did not. Resistance to anoikis correlated with PKB/Akt activation in suspension, but not with changes in PTEN or p110alpha P13 kinase levels.