| Abstract |
A cloned bovine mammary epithelial cell line (PS-BME-C1) cultured on EHS
(Englebreth-Holm-Swarm) matrix in serum-free media (SFM:DMA/F12 with 0.1
mg bovine serum albumin per ml, 10 micro g transferrin per ml, 5 mM sodium
acetate) will proliferate in response to treatment with insulin-like
growth factors (IGFs: 2 ng IGF-I per ml, 20 ng IGF-II per ml), EGF (20
ng/ml) or IGFs and EGF. EGF stimulates proliferation at a greater rate on
EHS matrix than on plastic substrata. Pretreatment for 21 days, with
insulin, cortisol and prolactin (IFP: 50 ng insulin per ml, 500 ng
cortisol per ml, 1 micro g prolactin per ml) reduces the ability of these
cells to respond to mitogens when the cells are cultured on or embedded
within the EHS matrix. Formation of mammospheres by the PS-BME cells is
potentiated by IFP and negated by IGFs/EGF. Cells stained with Nile Red
contain yellow fluorescent droplets indicative of neutral lipids. IFP
increases the uptake of 14C-acetate and its incorporation into lipids but
mRNA for alpha s1-casein is not detectable by Northern analysis (20 micro
g total RNA). Inability to synthesize milk proteins but retention of lipid
synthesis may indicate divergence of the 2 synthetic pathways in these
cells.
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