M6A RNA methyltransferases Mettl3/14 regulate immune responses to anti-PD-1 therapy
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ABSTRACT: An impressive clinical success has been observed in treating a variety of cancers using immunotherapy with programmed cell death-1 (PD-1) checkpoint blockade. However, limited response in most patients treated with anti-PD-1 antibodies remains a challenge, requiring better understanding of molecular mechanisms limiting immunotherapy. In colorectal cancer (CRC) resistant to immunotherapy, mismatch-repair-proficient or microsatellite instability-low (pMMR-MSI-L) tumors have low mutation burden and constitute ~85% of patients. Here, we show that inhibition of N6-methyadenosine (m6A) mRNA modification by depletion of methyltransferases, Mettl3 and Mettl14, enhanced response to anti-PD-1 treatment in pMMR-MSI-L CRC and melanoma. Mettl3 or Mettl14 deficient tumors increased cytotoxic tumor-infiltrating CD8+ T cells and elevated secretion of IFN-?, Cxcl9 and Cxcl10 in tumor microenvironment in vivo. Mechanistically, Mettl3 or Mettl14 loss promoted IFN-?-Stat1-Irf1 signaling through stabilizing the Stat1 and Irf1 mRNA via Ythdf2. Finally, we found a negative correlation between METTL3 or METTL14 and STAT1 in 59 patients with pMMR-MSI-L CRC tumors. Altogether, our findings uncover a new awareness of the function of RNA methylation in adaptive immunity and provide METTL3 and METTL14 as potential therapeutic targets in anticancer immunotherapy.
SUBMITTER: Prof. Tariq, M Rana
PROVIDER: S-SCDT-EMBOJ-2020-104514 | biostudies-other |
REPOSITORIES: biostudies-other
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