[TET2 as a gatekeeper for hematologic malignancies].

TET (Ten Eleven Translocation) family proteins are dioxygenases that convert methylcytosine to hydroxymethylcytosine, and play an important role in the DNA demethylation process. Most notably, TET2 mutations have frequently been identified in myeloid malignancies, such as myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), chronic myelomonocytic leukemia, and acute myeloid leukemias, as well as angioimmunoblastic T-cell lymphoma and a proportion of peripheral T-cell lymphomas. To date, various types of Tet2 knockout/knockdown mice have been generated. Tet2 mutations induce enhanced self-renewal ability and competitive repopulation capacity in hematopoietic stem cells, and various MPN/MDS-like diseases and T-cell lymphoma consequently develop in model mice. These findings appear to have a strong correlation with the recently identified TET2 mutations in a significant proportion of healthy elderly people, and suggest that TET2 mutations lead to a pre-cancer state in hematopoietic stem/progenitor cells. In conclusion, TET2 might play a major role as a gate keeper for hematopoietic stem/progenitor cells preventing them from developing into various hematologic malignancies by acquiring additional disease-specific gene mutations.