FIG. 4.

p53-controlled gene expression is not altered by inhibition of SIRT1 in several p53-positive cell lines. (A) NCI-H460, MCF-7, U-2 OS, and HMEC were treated with various concentrations of etoposide for 6 h in the presence of 1 μM EX-527 or dimethyl sulfoxide vehicle (DMSO). Levels of p21 mRNA were measured using quantitative PCR and normalized to the expression levels of hypoxanthine phosphoribosyltransferase (HPRT). (B) NCI-H460 cells were treated with etoposide or adriamycin in the presence or absence of EX-527 for 6 h. Cell lysates were prepared for immunoblotting and were probed with antibodies directed against p21 and tubulin. +, present; −, absent.