In addition, G extract also caused a parallel down-regulation of the anti-apoptotic UHRF1 and its partner DNMT1. Similarly, the natural anti-cancer drug, epigallocatechin-3-gallate has been shown to induce p16INK4A re-expression-dependent pro-apoptotic pathway via the down-regulation of UHRF1 in Jurkat cells [19]. Moreover, a recently published study has shown that UHRF1 depletion in cancer cells causes G2/M cell cycle arrest and click here apoptosis accompanied with phosphorylation of cyclin-dependent kinase 1 (CDK1) [37] which is in agreement with our present data. UHRF1 is an oncogene protein known to bind to methylated DNA and to see more recruit

the DNMT1 to regulate tumor suppressor gene expression including p16INK4A[38]. Here, we showed that

G extract decreased the expression UHRF1 as well as DNMT1. This effect was accompanied with an up-regulation of tumor suppressor gene p16 INK4A . As UHRF1 is a negative regulator this website of p16INK4A expression involving DNMT1 [19, 36], our results suggest that the mechanism of action of G extract involves, at least in part, a down-regulation of UHRF1 with subsequent down-regulation of DNMT1 leading to an up-regulation of p16 INK4A gene inducing G2/M cell cycle arrest. In agreement with this hypothesis, we have recently shown that curcumin inhibited melanoma cell proliferation and cell cycle progression by accumulating cells at the G2/M-phase with decreased expression of UHRF1 and DNMT1 and enhanced expression of p21, a p16INK4A -homolog [39].

Furthermore, because of CDK1 is required for progression of cells from the G2 phase into and through mitosis, down regulation of UHRF1 after cell treatment with G extract might also induce CDK1 phosphorylation and causes the G2/M cell else cycle arrest and apoptosis as previously described in UHRF1 depleted cells [37]. Considering that G extract has a high quantity of polyphenolic compounds, we hypothesized that these products could be involved in the anti-proliferative and pro-apoptotic effects on HeLa cells. So, in order to obtain evidence for this hypothesis, the dietary flavonoid luteolin has been used in this study. Several studies have shown that flavonoids have anti-cancer effect on cancer cells involving several mechanisms including, cancer cells elimination, cell-cycle progression inhibition and induction of apoptosis [40–42]. Our results indicate that luteolin inhibits cell proliferation, arrests cell cycle progression and induces apoptosis in HeLa cells. A similar mechanism has also been involved in the effect of luteolin on cell cycle and apoptosis in HeLa cancer cells [43].