Integrin alphavbeta3 promotes anchorage-dependent apoptosis in human intestinal carcinoma cells

A population of cells surviving during prolonged incubation in suspension (anoikis-negative cells) were selected from the original anoikis-positive human intestinal carcinoma cell line Caco-2. Anoikis-negative cells are characterized by a strong transcriptional downregulation of the alphav-integrin chain as detected by FACS analysis, RT-PCR and Northern blotting. This finding suggested that alphav-integrin generates a signal stimulating apoptosis of Caco-2 cells upon their detachment from the extracellular matrix. Two lines of evidence supporting this suggestion were provided. First, activation of the alphavbeta3 integrin on Caco-2 cells by their treatment with an alphavbeta3-specific monoclonal antibody resulted in marked stimulation of anoikis. Second, treatment of Caco-2 cells with alphav-specific antisense oligonucleotide resulted in downregulation of the expression of alphav chain and in elevated resistance of these cells to anoikis. Thus, for the first time, our data prove that alphavbeta3 integrin can be an active transducer of apoptosis-stimulating signals generated in response to disruption of the cell-matrix contacts.