4. Targeting UHRF1 abundance by natural compounds Targeting UHRF1 abundance and/or UHRF1′s enzymatic activity would have Dactolisib in vivo application in several types of cancer. UHRF1 is essential for cell proliferation and therefore, to our opinion it would be more rational see more to target cancer types in which UHRF1 is actually found in high abundance, i.e., over-expressed. UHRF1 has been reported to be over-expressed in various cancers such as breast, bladder, kidney, lung, prostate, cervical, and pancreatic cancers, as well as in astrocytomas and

glioblastoma [35, 40, 61]. The anticancer strategic idea would be not to completely inhibit UHRF1 expression considering that UHRF1 is also necessary for non cancerous to proliferate [44, 62, 63], hence, for instance, for physiologic tissue regeneration. Thus, to consolidate the anti-UHRF1 therapeutic interest, it would be interesting to show that diminishing but not abolishing UHRF1′s expression by chronic treatment of natural compound is sufficient for re-expression of silenced tumor suppressor genes. An ideal property for

future natural compounds as anti-cancer drugs, would be that cancer CHIR98014 cells but not normal cells are affected by them in order to undergo apoptosis via an UHRF1 down-regulation. Targeting UHRF1 is particularly interesting because this protein regulates the G1/S transition [47–49, 62, 63]. The arrest at G1/S checkpoint is mediated by the action of the tumor suppressor gene p53 or its functional homologue p73 [64, 65]. Recent years have seen a dramatic progress in understanding mechanisms that regulate the cell division. In this context, we and other groups have shown that UHRF1 is essential for G1/S transition [63]. Loss of Osimertinib p53 activity, as a result of genetic mutations or epigenetic alterations in cancer, prevents G1/S checkpoints. DNA damage induces

a p53 or p73 up-regulation (in p53-deficient cells) that activates the expression of p21 cip/waf or p16 INK4A , resulting in cell cycle arrest at G1/S transition [65, 66]. We have shown that UHRF1 represses the expression of tumour suppressor genes such as p16 INK4A & RB1 leading to a down-regulation of the Vascular Endothelial Growth Factor (VEGF, Figure 2A) [49] and by a feedback mechanism, UHRF1 may be regulated by other tumour suppressor genes such as p53 and p73 products [46, 67]. This suggests that the appearance of genetic and/or epigenetic abnormalities of TSGs including p53 and p73 genes, in various human cancers would be an explanation for the observed UHRF1 over-expression. Since UHRF1 controls the duplication of the epigenetic code after DNA replication, the inability of p53 and P73 to down-regulate UHRF1, allows the daughter cancer cells to maintain the repression of tumour suppressor genes observed in the mother cancer cell [26, 68].