Expression of p53 mRNA is proliferation-dependent in the human fibroblast cell line WI-38

Abstract. Although alterations in the p53 tumour suppressor gene are one of the most frequent genetic lesions occurring in human cancers, the exact function and mechanism of action of normally regulated p53 in the control of cell cycle is unclear. To clanfy further the possible role of this gene in the control of cell proliferation, the cellular level of p53-specific mRNA and its changes during density-dependent growth, and in different proliferation states induced by serum starvation and subsequent serum-stimulation, were followed in WI-38 cells, a normal human diploid fibroblast cell line. Marked differences in the expression of p53 mRNA could be observed in the different proliferation states tested. The pattern of p53 expression proved to be inversely proportional to the growth-rate of the cultures. mRNA was considerably more abundant when cells reached confluency or were arrested by serum deprivation while serum-stimulation caused the opposite effect. These results support the hypothesis that the p53 gene plays a role in G₁ control of normal cell proliferation.