Abstract 992: Credentialing UHRF1 as a target for prostate cancer therapy

Abstract

Abstract Alterations in DNA methylation are a hallmark of prostate carcinogenesis. UHRF1 is an essential component in the machinery required for the maintenance of DNA methylation in actively dividing cells. In S-phase, UHRF1 binds nascent hemimethylated DNA and recruits DNA methyltransferases to copy the methylation pattern to the daughter DNA strand in a manner analogous to semi-conservative replication. Additionally, it has been shown that UHRF1 interacts with methylated histones and histone methyltransferases, making it an important epigenetic regulator in proliferating cells. Because of its ties to epigenetic gene silencing and cell proliferation, we hypothesized that UHRF1 could serve as a target for prostate cancer treatment. In this study, we have taken steps to credential UHRF1 as a therapeutic target in prostate cancer and have developed a high-throughput UHRF1-DNA binding assay to screen for UHRF1 inhibitors. We show that UHRF1 is overexpressed in a panel of prostate cancer cell lines and it appears to track with proliferation in prostate cancer tissue. Through loss-of-function studies in prostate cancer cell lines PC3 and DU145, we show that long-term UHRF1 depletion leads to a decrease in clonogenic survival and an overall reduction in global levels of DNA methylation. Further, we find that UHRF1 is required to maintain DNA methylation and epigenetic silencing of hypermethylated genes in prostate cancer cells. Additionally, ChIP experiments revealed that UHRF1 can be bound at the promoter CpG islands of epigenetically silenced genes in prostate cancer cells. With the goal of ultimately developing UHRF1 inhibitors, we have developed a time-resolved fluorescence resonance energy transfer (TR-FRET)-based assay, compatible with high-throughput screening, that can detect the binding of the SRA domain of UHRF1 to hemimethylated DNA. In summary, we have shown that UHRF1 plays a critical role in maintaining the DNA methylation of epigenetically silenced genes in prostate cancer and have developed an assay for high-throughput screening of UHRF1 inhibitors. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 992. doi:1538-7445.AM2012-992