The effect of MS-275 on the proliferation of patient derived cutaneous squamous cell carcinoma cell lines.

(A) cSCC-IC4 (IC50 = 1.24 ± 0.05 μM) and (B) cSCC-MET4 (IC50 = 0.10 ± 0.02 μM) cells were seeded in 96-well plates for 24 h prior to addition of the indicated amount of inhibitor in DMSO (final concentration of DMSO was 0.5%). Cells were cultured for an additional 72 h with [3H]thymidine being added 6 h prior to harvesting cells. Radioactivity was measured using a Microbeta scintillation counter and normalized to vehicle treated controls (IC50 = mean ± SE, n = 4). Representative Western blots in (C) cSCC-IC4 and (D) cSCC-MET4 cell lines depicting dose dependent increases in p21 levels upon treatment with the indicated amount of drug for 24 h. GAPDH and p21 were detected in samples that were run on the same gel. After transfer to a nitrocellulose membrane, the membrane was cut at the 25 kDa marker and membrane sections were incubated with the indicated primary antibody. Quantitation of p21 levels by densitometry for (E) cSCC-IC4 and (F) cSCC-MET4 cell lines using ImageJ (n = 3, unpaired t test, *p p < 0.01).