show Abstracthide AbstractUHRF1 (ubiquitin-like with PHD and ring finger domains 1) is an epigenetic regulator that is involved in the regulation of DNA and histone methylation and many other cellular events. The UHRF1 is frequently found to be overexpressed in various human cancers, and its overexpression has been associated with pro-tumorigenic effects such as inhibition of apoptosis and high metastatic potential. However, the molecular mechanisms underlying these pro-tumorigenic effects of UHRF1 overexpression in cancers still remain unclear. Retinoblastoma (Rb) is an intraocular tumor which arises from developing retina by biallelic inactivation of Rb1 gene. In this study, we uncovered that the UHRF1 is highly expressed in retinoblastoma, and genomes of retinoblastoma have differential DNA methylation patterns compared to those of normal retina, characterized by global hypomethylation and promoter hypermethylation at key tumor suppressor genes. Given the well-documented functions of UHRF1 in the regulation of DNA methylation, we hypothesized that the overexpressed UHRF1 may contribute to the aberrant DNA methylation in retinoblastoma genomes. To test our hypothesis, we profiled the genome-wide methylation patterns in normal retina and Y79 retinoblastoma cell line by MeDIP-seq, and then investigated how the methylation patterns in Y79 are affected by down-modulation of UHRF1. For identification of differentially methylated regions between the control and UHRF1 knockdown Y79 cells, we analysed three independent sets of sequencing data to unambiguously determine the effects of UHRF1 down-modulation on the methylome of Y79 retinoblastoma cells.