Inhibition of NNMT leads to a methyl overflow, which enhances trimethylation of histone H3K9 and increases DNA methylation at the promoters of PRDM5 and extracellular matrix-related genes in cancer cells, therefore being regarded as a promising anti-cancer target (Gao et al., 2021; Li et al., 2022; Couto et al., 2023; Sun et al., 2024). This evidence concerns the gene NNMT and cancer.