DNA methylation at gene promoter regions of tumor suppressor genes

DNA methylation at gene promoter regions—especially those controlling tumor suppressor genes—is an epigenetic mechanism involving the addition of a methyl group to cytosines within CpG dinucleotides by enzymes called DNA methyltransferases. In healthy cells, these promoters are typically unmethylated and transcriptionally active. In many cancers, however, these promoters become abnormally hypermethylated, leading to stable transcriptional repression ("gene silencing") without altering the underlying genetic sequence. This process contributes directly to carcinogenesis by functionally inactivating key regulators like TP53, CDKN2A/p16INK4a, RASSF1A, MLH1 among others—thereby promoting uncontrolled proliferation and evasion from apoptosis.[1][3] This aberrant hypermethylation can be reversed pharmacologically using DNMT inhibitors such as azacitidine or decitabine.[2] The pattern and extent of this modification serve as important biomarkers for cancer diagnosis/prognosis and may predict response/resistance to certain therapies.[5] However, targeting this process therapeutically poses challenges due to potential off-target effects on normal tissue epigenomes.[4]

Other names

Promoter DNA methylationTumor suppressor gene promoter hypermethylationEpigenetic silencing of tumor suppressorsCpG island hypermethylation (in context of promoters)

Inhibition of DNA methyltransferases to reduce or reverse aberrant promoter hypermethylation, leading to reactivation of silenced tumor suppressor genes and restoration of normal cellular functions such as apoptosis and cell cycle arrest.