We studied whether acquisition of multidrug resistance (MDR) by tumor cells can alter their integrin profile and malignant behavior. Hamster fibroblast cell line HET-SR-2SC-LNM was selected for MDR, yielding the 2SC/20 subline. Compared with the parental cells, the 2SC/20 subline weakly adhered to denatured collagen (dCol) which correlated with decreased expression of alphavbeta3, a dCol receptor. Importantly, 2SC/20 subline demonstrated significantly decreased activity of collagenase MMP-2, lower ability to invade Matrigel, and attenuated metastasis in syngeneic animals. We provide evidence for the first time that selection for MDR can be associated with down-regulation of alphavbeta3 integrin, supporting our recent proof of the pro-apoptotic role of this integrin (Oncogene 20 (2001) 4710). Lack of alphavbeta3 expression may link cell survival under toxic conditions with decreased malignancy of the resulting drug resistant tumor. (C) 2004 Elsevier Inc. All rights reserved.