Experimentally, METTL3 overexpression impaired the TMZ-sensitivity of glioblastoma cells, while METTL3 silencing or 3-deazaadenosine (DAA)-mediated total methylation inhibition improved the sensitivity of TMZ-resistant glioblastoma cells to TMZ in vitro and in vivo. Here, METTL3 is linked to glioblastoma.