An antisense oligonucleotide targeting the alpha V integrin gene inhibits adhesion and induces apoptosis in breast cancer cells

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 alpha V integrin subunit in breast cancer cells. The alpha V integrins play major roles in favouring breast cancer spreading. In this study. we inhibited alpha V subunit synthesis in the human breast carcinoma cell line, MDA-MB231, by a partially phosphorothioated antisense oligodeoxynucleotide (5543-ODN). The alpha V antisense 5543-ODN reduced alpha V, but not actin, mRNA transcription and protein expression by 55% and 65% respectively (1 mu M, 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 alpha V integrin was located in adhesion structures, which were disrupted by treatment with the alpha V 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. (C) 2000 Elsevier Science Ltd. All rights reserved.