In order to explore the synergistic roles of two methyltransferase members Dnmt3a and Dnmt1, we constructed expression plasmid that could express a recombinant DNMTs consisting of the C‐terminal domains of both Dnmt3a and Dnmt1 fused to a zinc finger domain which binds to the PD‐L1 promoter of human prostate cancer cells (DU145). This evidence concerns the gene DNMT3A and prostate cancer.