Screening The Small Molecule Inhibitors Targeting The SRA Domain Of UHRF1

The aberrant DNA methylation has become one of important biomarkers for tumor diagnosis,treatment and prognosis..By inhibiting DNA methyltransferase(DNMT)activity,reversing the abnormality of DNA methylation patterns in tumor cells and promoting the reexpression of related tumor suppressor genes,it has been an important method for cancer treatment.UHRF1,an important accessary protein for maintenance DNA methyltransferase DNMT1,recognizing hemimethylated CpGs generated during DNA replication via its unique SRA domain and subsequently recruits DNMT1 through both direct and indirect-interaction with DNMT1,is highly expressed in many tumor cells and serves as a potential target for tumor therapy.As UHRF1 is critical for DNA maintenance methylation by DNMT1,we wish to screen for small molecule compounds that can inhibit the binding of hemimethylated DNA by the SRA domain of UHRF1.As a collaboration,Prof.Huaiyu Yang’s laboratory carried out a visual screening based on the reported SRA structure.We then used EMSA assay to test in total of 116 small molecule compounds derived from the visual screen for their ability to inhibit the binding of UHRF1 to hemimethylated DNA in vitro.Six compunds were identified with ability to inhibit SRA binding in vitro.Subsequent cell culture experiments revealed that treatment with the compounds #42 and #68 resulted in reduced overall levels of DNA methylation.In addition,we found that these compounds can inhibit cell proliferation and have no effect on UHRF1 transcription and protein stability.Furthermore,we found these compounds work coorperatively with the DNMT inhibitors in blocking tumor cell proliferation,despite a lack of coorperative inhibition of DNA methylation.In summary,our study has identified two novel compounds that may serve as potential small molecule inhibitor for UHRF1 mediated DNA methylation and tumor cell proliferation.