INTERNALIZATION AND BIOLOGICAL EFFECTS OF SERUM-ALBUMIN IN THE BREAST-CANCER MCF-7 AND MDA-MB-231 CELLS

We show that albumin is internalized by human breast cancer cells (MDA -MB 231 and MCF-7) in culture by using confocal laser scanning microsc opy. Moreover, albumin has an effect on the level of radioactivity inc orporated when the cells are incubated with radioactive estradiol, and it is necessary to observe the mitogenic effect of estradiol towards the MCF-7 cells. This finding opens some possibilities regarding the i nternalization mechanisms and fate (degradation, recycling) of albumin as well as the role played by this protein in the intracellular metab olism of estradiol and in the intra-extracellular traffic of estradiol and its metabolites.