Figure 5

Effects of laminin on estrogen-induced proliferation, progesterone receptor regulation and estrogen receptor activity in ER positive human breast cancer cell lines. (a) MCF-7 and T47D cells were cultured in serum-free medium containing EGF (5 ng/ml), IGF-I (25 ng/ml) on various ECM proteins. Cells were pre-treated with 200 nM ICI 182,780 for 48 hour followed by no treatment (control) or 17β-estradiol (20 nM); ³H-thymidine incorporation into DNA was determined 21 hour later. ^* P < 0.05 that estrogen-treated groups are greater than control-treated groups. (b) MCF-7 cells were cultured in serum-free medium in the absence (control) or presence of estrogen (10 nM) for 3 days. Progesterone receptor concentrations were determined by specific ³H-R5020 binding assay. ^* P < 0.05 that estrogen-treated groups are greater than control groups. (c) MCF-7 cells were transfected with estrogen response element (tk109-luc) and β-galactosidase plasmids. Luciferase activity was measured 24 hour after ICI 182,780 (200 nM), control or estrogen (10 nM) treatment. Luciferase activity was normalized to transfection efficiency determined by β-galactosidase activity/cell. ^* P < 0.05 that estrogen-treated groups are greater than control groups. ^** P < 0.05 that estrogen-treated LM group is less than estrogen-treated Col I or FN groups. (Adapted from [15] with permission from Endocrinology). Col, collagen; FN, fibronectin; LN, laminin; PL, poly-L-lysine; VN, vitronectin.