DNMT1 and colorectal cancer: In this study, a specific regulatory mechanism of PCSK9 expression in colorectal cancer (CRC) tumor cells was discovered, wherein methionine catabolism promotes mRNA transcription of PCSK9 by facilitating DNA methylation mediated by DNA methyltransferase 1 (DNMT1) and suppressing sirtuin 6 (SIRT6) expression.