DNMT1 mediates chemosensitivity by reducing methylation of miRNA-20a promoter in glioma cells

An enzyme called DNA methyltransferase regulates the expression of a microRNA to affect the drug sensitivity of gliomas cancer cells. Xuchen Qi and colleagues from Sir Run Run Shaw Hospital and Zhejiang University in Hangzhou, China, showed that DNA methyltransferase, an enzyme that adds chemical tags onto DNA to control gene expression levels, was less active in glioblastoma cancer cells that are resistant to treatment with temozolomide, a common chemotherapeutic agent, than in temozolomide-sensitive cells. The low levels of DNA methyltransferase in turn produced fewer chemical tags on the DNA responsible for limiting expression of microRNA-20a, a small regulatory RNA. Consequently, microRNA-20a levels were greater in temozolomide-resistant cells. The findings point to two potential therapeutic strategies for treating glioma: boosting DNA methyltransferase activity or inhibiting microRNA-20 directly.