The mRNA phenotype of a human RPE cell line at replicative senescence

Purpose: To explore the changes in expression of a set of genes in a single retinal pigment epithelial (RPE) cell line and two fibroblast cell lines a s controls under culture conditions previously used for the analysis of sen escent gene expression. Methods: A single human RPE cell line, which had previously been characteri zed using known markers of senescence, and two fibroblast cell lines were g rown to replicative exhaustion. The mRNA phenotype of genes known to be alt ered by senescence were studied by quantitative Northern analysis. Results: The mRNA phenotype of cells changes at replicative senescence yiel ding a synthetic phenotype which is similar to cells found in repairing wou nds. Of the genes studied, urokinase-type plasminogen activator and plasmin ogen activator inhibitor-1 were regulated in RPE cells similar to fibroblas ts at senescence. The largest changes noted for any single gene were the up regulation of insulin growth factor binding protein 2, and the downregulati on of collagen I alpha 2, basic fibroblast growth factor, and fibroblast gr owth factor-5. Conclusions: This study demonstrates an altered mRNA phenotype of a human R PE cell line grown to replicative exhaustion. This analysis of a single cel l line emphasizes the variability of results based on a single cell line or tissue specimen and indicates the need for additional study.