Differential effects of selenium on the growth of mouse mammary cells in vitro.

The effect of selenium was examined on the growth potential of normal, preneoplastic and neoplastic mammary cells grown in primary monolayer cell cultures and on 3 established mammary cell lines. Selenium, present as Na2SeO3 in serum-free DMEM, inhibited all mammary cell cultures at 1 x 10(-5) M. Selenium, at 5 x 10(-8) M, stimulated the growth of primary cell cultures of normal mammary cells and C4 preneoplastic cells and the established cell line YN-4, but not the growth of D2 preneoplastic cells and tumors in primary cell cultures and of established cell lines CL-S1 and WAZ-2t. The differential responses of cells from preneoplastic outgrowth lines C4 and D2 and of D2 primary tumors in vitro correlated with the sensitivity of these same cell populations to selenium-mediated inhibition of growth and tumorigenesis in vivo. The differential responses among the 3 cell lines will allow further comparative studies on the cell biological basis of selenium function.