Potential role of beta 1 integrin and collagen biosynthesis in estrogen-dependent reduction of apoptosis in tamoxifen-treated breast cancer cells

It was found that 10 muM tamoxifen induced apoptosis and a significant (app roximately 50%) depletion of pi integrin levels in human breast cancer cell s. Estradiol-treated MCF-7 cells exhibited exceptional viability and adhere nce, high levels of beta1 integrin and increased (by 100%) collagen biosynt hesis. Pretreatment of MCF-7 cells with 1 nM estradiol prevented tamoxifen- induced cell death, loss of cell adherence and decrease in beta1 integrin l evel. Tamoxifen and estradiol had an opposite effectonthe beta1 integrin le vel and adherence in breast cancer cells, suggesting that the decrease in t he pi integrin level may be an early event during tamoxifen-induced apoptos is in breast cancer cells. Copyright (C) 2001 S. Karger AG, Basel.