CELL DENSITY-DEPENDENT REGULATION OF BASIC FIBROBLAST GROWTH-FACTOR EXPRESSION IN HUMAN RENAL-CELL CARCINOMA-CELLS

We investigated some of the mechanisms that regulate the expression of basic fibroblast growth factor (bFGF) in human renal cell carcinoma ( HRCC). HRCC SN12PM6 cells were cultured as adherent monolayers, The ex pression of steady-state bFGF mRNA (measured by in situ hybridization and Northern blot) and protein (measured by immunohistochemistry and E LISA) correlated inversely with the culture density, Tumor cells harve sted from dense cultures (low bFGF expression) and plated under sparse conditions expressed high levels of bFGF mRNA and protein prior to ce ll division, suggesting that bFGF may be a competence factor, Similar data were obtained with human vascular endothelial cells. The expressi on of bFGF was not regulated by spent culture medium, cell cycle, or r ate of cell division but was down-regulated by contact inhibition. The se data show that the expression of bFGF in HRCC is cell density depen dent.