The aim of this study was to show the anti-adhesive potential of an antisense oligodeoxynucleotide (ODN) approach when designed to suppress the cellular function of the alphaV integrin subunit in breast cancer cells. The alphaV integrins play major roles in favouring breast cancer spreading. In this study, we inhibited alphaV subunit synthesis in the human breast carcinoma cell line, MDA-MB231, by a partially phosphorothioated antisense oligodeoxynucleotide (5543-ODN). The alphaV antisense 5543-ODN reduced alphaV, but not actin, mRNA transcription and protein expression by 55% and 65% respectively (1 microM, 72 h). Control sense and mismatch reagents were inactive. The antisense, but not the sense and mismatch, 5543-ODN induced dose- and time-dependent inhibition of MDA-MB231 adhesion to serum, vitronectin, fibrinogen and fibronectin substrates but was inactive on adhesion to laminin. Thus, the alphaV integrin was located in adhesion structures, which were disrupted by treatment with the alphaV antisense 5543-ODN. Antisense treated cells also showed evidence of programmed cell death with the appearance of apoptotic bodies. MDA-MB231 cells express a mutant form of the pro-apoptotic factor p53; however, no changes in the expression of p53 were observed by Western blotting. Immunofluorescence did reveal an increased nuclear translocation of p53 suggesting activation of the protein, but such a translocation did not lead to significant changes in either the expression of the cyclin dependent kinase inhibitor, p21(WAF1/CIP1) the cell survival factor Bcl-2 or the pro-apoptotic factor Bax.