An in vivo study has demonstrated that RWPs administrated with diet to rats inhibited azoxymethane-induced colon carcinogenesis [96], but the involved

molecular mechanism remains unclear. Thus, to confirm in vivo the pathways involved in the protective effects of RWPs, we used a mouse model of colorectal cancer, by sub-cutaneously injecting C26 cells [97]. By using micro-angiography and immunohistochemistry approaches, PLX3397 in vivo we showed that regular consumption of RWPs in the drinking water decreased C26 tumour vascularization in BALB/C mice as a consequence of decreased expression of major proangiogenic factors including VEGF, matrix metalloproteinase 2 and 9, and cyclooxygenase-2 [97]. The RWPs-induced down-regulation of proangiogenic factors was associated with an activation of various TSGs such as p53, p73, p16 INK4A and the cell cycle regulator p21 Waf1/Cip1 . Interestingly, a strong immunostaining for UHRF1 was observed in the tumours from the control group, whereas low staining was found in those from RWPs-treated group. These results suggest a specific role of this epigenetic actor in the progression of colorectal tumor. Therefore, UHRF1 abundance is likely a preferred target of RWPs in C26 cells-induced tumorigenesis mouse model. However, the precise mechanism by which RWPs

induce the up-regulation of TSGs in colorectal cancer models is presently unclear. Recently, it has been shown

that apple polyphenols has potent DNA demethylation activity in colorectal cancers by reducing DNMT1 expression with a subsequent activation of TSGs such P005091 price as hMLH1, p14 ARF and p16 INK4A . These genes are known to be silenced through their promoter hypermethylation in colorectal cancers [98]. Consistently with this, it was PI3K inhibitor recently shown that the polyphenol epigallocatechin gallate allows re-expression of p16 INK4A and p21 Waf1/Cip1 through a DNA demethylation dependent process probably involving a down-regulation of DNMT1 [99]. In agreement with our previous L-NAME HCl studies [49, 67], we propose two mechanisms targeting UHRF1 and underlying the antitumoral activities of RWPs in colorectal cancer. First, considering that UHRF1 binds to methylated promoters of TSGs, i.e., p16 INK4A [44], and that UHRF1 interacts with DNMT1 and regulates its expression [49], it is likely that the RWPs-induced down-regulation of UHRF1, with subsequent decrease of DNMT1, could be involved in the demethylation of the p16 INK4A promoter (Figure 2B). Second, RWPs could trigger cell cycle arrest and apoptosis in colorectal cancer by activation of p53 and p73 which are negative upstream regulators of UHRF1 [46, 67]. These findings suggest that RWPs exert their antitumoral activities in colorectal cancer through a mechanism of feedback control involving TSGs and UHRF1 (Figure 3B).