EXPRESSION AND REGULATION BY SERUM OF MULTIPLE FGF1 MESSENGER-RNA IN NORMAL TRANSFORMED, AND MALIGNANT HUMAN MAMMARY EPITHELIAL-CELLS

In normal (NMEC), transformed (HBL-100) and malignant human mammary ep ithelial cells (MCF 7, BT-20, MDA-MB 231), we have examined the expres sion and the regulation by serum of FGF1 and FGF2 mRNA. FGF2 mRNA leve l was higher in NMEC and in a HBL-100 than in malignant cell lines (MD A-MB-231, BT-20). No FGF2 mRNA was detected in the malignant cell line , MCF-7. In contrast, the FGF1 mRNA was detected in all the mammary ep ithelial cells but at different levels. NMEC, HBL-100 and MDA-MB-231 c ells expressed similar level of FGF1 and higher than that observed in BT-20 and MCF-7. In contrast to FGF2 which is only expressed in nonmal ignant cells, no correlation between FGF1 mRNA expression and the phen otype of the cells was observed. We followed the expression of four FG F1 mRNA, heterogenous in their 5' untranslated regions. This study dem onstrated that (i) the FGF1 mRNA 1.A was not expressed by mammary epit helial cells, (ii) the FGF1 mRNA 1.B was only expressed in normal mamm ary epithelial cells and (iii) the transcripts 1.C and 1.D were expres sed in normal and malignant cells with specific patterns. The expressi on of FGF1 mRNAs responded in a cell specific manner to serum starvati on. The mRNA 1.A was only expressed in normal cells cultured in the ab sence of serum while 1.C was either up- or down-regulated by serum in transformed cells and the expression of 1.D was greater in presence of serum in all cell lines. These results show that the regulation of FG F1 mRNAs expression is cell specific and does not correlate with a tum origenic or transformed cell phenotype. (C) 1996 Academic Press, Inc.