ROLE OF ALPHA-V-BETA-5 AND ALPHA-V-BETA-6 INTEGRIN GLYCOSYLATION IN THE ADHESION OF A COLONIC ADENOCARCINOMA CELL-LINE (HT29-D4)

We have previously characterized the expression of the alpha v beta 5 and alpha v beta 6 integrins as major receptors for the human colonic adenocarcinoma cell line (HT29-D4), on vitronectin and fibronectin, re spectively [Lehmann et al. (1994): Cancer Res 54:2102-2107]. In the pr esent work we investigated the glycosylation role of these integrins i n their adhesive functions. To this end, we used glycohydrolases to sh ow that cell surface integrins were N-glycosylated and sialylated, and that only the cuv subunit carried some immature oligosaccharide side chains. To alter the glycosylation state of the cell surface alpha v b eta 5 and alpha v beta 6 integrins, we used two oligosaccharide-proces sing inhibitors: 1-deoxymannojirimycin (dMNJ) and tunicamycin (TM). Fo llowing treatment of HT29-D4 cells with dMNJ, cell surface alpha v bet a 5 and alpha v beta 6 carried only high-mannose-type sugar chains, wh ile TM-treated cells expressed de-N-glycosylated integrins. Neither al pha/beta heterodimers assembly nor cell surface expression were impair ed in the presence of the drugs. Finally, we established that adhesion of dMNJ- or TM-treated cells was altered on both vitronectin and fibr onectin substrata, whereas the adhesion of these cells on laminin or c ollagen type I was virtually unchanged. (C) 1996 Wiley-Liss, Inc.