TET activators are compounds that enhance the activity of Ten-Eleven Translocation enzymes (TET1, TET2, and TET3), which catalyze the oxidation of 5-methylcytosine (5mC) into 5-hydroxymethylcytosine (5hmC), initiating active DNA demethylation. Endogenous metabolites play a critical role in regulating TET function: α-ketoglutarate (α-KG) serves as an essential co-substrate, while vitamin C (ascorbic acid) maintains catalytic activity by regenerating Fe(II) within the enzyme's active site.

Pharmacological Activators

Several synthetic compounds have been identified as pharmacological activators of TET enzymes. Mitoxantrone, an FDA-approved anticancer drug, was discovered through high-throughput screening to act as a potent TET agonist, increasing 5hmC levels and promoting TET-dependent cell death in leukemia models. In addition, the GLIX series represents a new class of orally available small molecules that selectively restore TET2 activity. The lead compound, GLIX1, induces extensive DNA damage in cancer cells, demonstrates strong brain penetration, and has shown promising antitumor efficacy in glioblastoma xenograft models.

Indirect Activators and Natural Compounds

• IDH inhibitors: Agents such as ivosidenib and enasidenib indirectly restore TET activity by reducing intracellular levels of 2-hydroxyglutarate (2-HG), an oncometabolite that competitively inhibits TET enzymes.
• Natural compounds: Molecules including retinoic acid, resveratrol, curcumin, and sulforaphane may enhance TET1 expression through modulation of epigenetic regulatory pathways.
• DNA methyltransferase inhibitors: Compounds such as 5-azacytidine can increase TET1 expression as part of a compensatory response to DNA hypomethylation, contributing to epigenetic remodeling.