We assessed global genomic DNA methylation by Imprint® Methylated DNA Quantification assay. As shown in Table 2, a general decrease in genomic DNA methylation was evidenced by both natural products. Indeed, our results demonstrate that G extract and luteolin inhibited DNA methylation as compared to untreated cells

(Table 2) with percent inhibition of 42.4% ± 1.6% and 46.5% ± 1.1% selleck in the presence of G extract and luteolin, respectively. Altogether, these findings showed that both G extract and luteolin were able to decrease UHRF1 and DNMT1 expression leading to a reduced genomic DNA methylation which could induce the re-expression of the p16 INK4A tumor suppressor gene. Table 2 Effects of aqeous gall extract and luteolin on global methylated Selleckchem AUY-922 DNA in HeLa cells Average of absorbance (nm) Methylated DNA (%

of control) MC 0.662 ± 0.030 259.90* ± 4.9 C 0.283 ± 0.001 100.00 G200 0.152 ± 0.003 53.53* ± 1.52 L25 0.163 ± 0.005 57.60 * ± 2.29 Total DNA was isolated from HeLa cancer cells using QIAamp® DNA Kit. the content of methylated DNA was determined using 200 ng of DNA from untreated cells (C), treated cells with 200 μg/ml of G extract (G200 or with 25 μM of luteolin(L25) for 48 hours and the commercial methylated Tideglusib price control (MC) (Imprint Methylated DNA Quantification Kit) Values are means ± S.E.M. of three independent experiments. Statistically significant, *P < 0.001 (versus the untreated cells). G extract and luteolin inhibit cell growth and induce cell cycle arrest of HeLa cells Considering that p16 INK4A tumor suppressor gene is a downstream target of UHRF1 and a negative regulator of cell proliferation [17, 36], we then wanted to determine whether G extract- or luteolin-induced up-regulation of p16INK4A

leads to cell proliferation inhibition and cell cycle arrest. As illustrated in Figure 2, exposure of HeLa cells to G extract (A) or luteolin (B) inhibited PIK3C2G cell proliferation in a dose- and time-dependent manner. The IC50 values were determined graphically and the inhibition percentages were calculated. Inhibition of proliferation of HeLa cells, by G extract, reached a maximum of 79.6% and 59.7% at a concentration of 300 μg/ml after 48 and 24 hours of incubation, respectively (Figure 2A). IC50 values were 170 μg/ml and 140 μg/ml of G extract after 24 and 48 hours treatment, respectively. Interestingly, G extract had no effect on normal human keratinocytes when cells were treated with similar concentrations for 24 and 48 hours (Figure 2C). This suggests that G extract specifically targets cancer cells. Figure 2 Aqueous gall extract and luteolin inhibit HeLa cell proliferation. HeLa cells and primary cultured human foreskin keratinocytes were treated with different concentrations of G extract (A and C) or luteolin (B) for 24 and 48 hours.