Figure 1.

Dose- and time-dependent inhibition of hTERT expression and telomerase activity in MCF10AT and MCF-7 cells treated with genistein. a, Genistein-induced cell growth inhibition in breast tumor cells without induction of cell death. MCF10AT (left) and MCF-7 (right) cells were plated in triplicate wells and exposed to various concentrations of genistein (0, 10, 25, 50 and 100 μM) for 3 days. Viable cells were counted by Trypan Blue staining using a hemacytometer. b and c, Dose- (left) and time-dependent (right) alterations of hTERT mRNA expression in MCF10AT and MCF-7 cells, respectively. Left, 24 hr after plating, cells were exposed to various concentrations of genistein. Right, the MCF10AT and MCF-7 cells were treated with genistein at a concentration of 50 μM and 100 μM for 3 days, respectively. Cell pellets were collected and subjected to real-time PCR and TRAP assay analysis. Relative quantification was performed by quantitative real-time PCR. Data are in triplicate from 3 independent experiments and were normalized to GAPDH and calibrated to levels in untreated samples. Bars, SE; *p < 0.05; **p < 0.001, significantly different from control. d and e, Dose- (left) and time-dependent (right) effect of genistein on telomerase activity in MCF10AT and MCF-7 cells. The internal control was evaluated for equal loading. Representative photograph from an experiment was repeated 3 times.