Knocking down p53 with siRNA does not affect the overexpression of p21 after exposure of IMR-90 hTERT fibroblasts to a sublethal concentration of HO leading to premature senescence

Premature senescence of IMR-90 human diploid fibroblasts (HDFs) expressing telomerase was induced by exposure to sublethal concentration of H O, with appearance of several biomarkers of cellular senescence like enlarged cell shape, senescence-associated β-galactosidase (SA β-gal) activity, and cell cycle arrest. The induction of stress-induced premature senescence (SIPS) was associated with a transient increase in DNA-binding activity of p53 and an increased expression of p21. p53 small interferent RNA (siRNA) affected the basal level of p21 mRNA but did not affect the overexpression of p21 after stress. This siRNA approach confirms previous results obtained with other methods.