Troglitazone suppresses the activity of telomerase in a dose and time dependent manner. A) Protein lysates (500 and 250 ng respectively) from MDA-MB-231 cells with no treatment (WT), treated with various concentrations of troglitazone (Tro) or the equal volume of DMSO for 24 hours were examined for telomerase activity by the TRAP assay. B) MDA-MB-231 cells were treated with 20 μM of troglitazone (Tro 20 μM) and the equal volume of DMSO for 24 and 48 hours. Protein lysate (500 and 250 ng respectively) from non-treated cells (WT), Tro 20 μM, and DMSO was used for the TRAP assay. A and B) I.C., the internal PCR amplification control. CHAPS, lysis buffer only as a negative control. HeLa, 500 cell equivalent lysate as a positive control. C) Total RNA was collected from DMSO and troglitazone treated cells for 24 hours and the mRNA expression level was measured by real-time RT-PCR. Data were normalized against the DMSO treated group (control) in the respective treatment condition. D) Total RNA from MDA-MB-231 cells treated with DMSO and 20 μM of troglitazone (Tro 20 μM) for 12 hours was extracted and the mRNA expression of hTERT was analyzed by real-time RT-PCR. Values express the relative quantity of hTERT to GAPDH. The final percentage of DMSO did not exceed 0.1% v/v. C and D) results shown are expressed as mean ± SD and are representative of at least three independent experiments. * p < 0.05.