DNMT1 and colorectal cancer: In addition, results have shown that treatment of colorectal cancer cells with berberine results in a significant increase in the expression of DNMT1 and DNMT3A in the presence of TGF-β1; this hypermethylation in the promoter CpG island leads to further silencing of TSG, which results in tumor cell proliferation (Riaz et al., 2015; Asadi et al., 2018; Nardi et al., 2018).