N6-methyladenosine (m6A) on mRNAs is critical for various biological processes, yet whether m6A regulates drug resistance remains unknown. Here we show that developing resistant phenotypes during tyrosine kinase inhibitor (TKI) therapy depends on m6A reduction resulting from FTO overexpression in leukemia cells. This deregulated FTO-m6A axis pre-exists in naïve cell populations that are genetically homogeneous and is inducible/reversible in response to TKI treatment. Cells with mRNA m6A hypomethylation and FTO upregulation demonstrate more TKI tolerance and higher growth rates in mice. Either genetic or pharmacological restoration of m6A methylation through FTO deactivation renders resistant cells sensitive to TKIs. Mechanistically, the FTO-dependent m6A demethylation enhances mRNA stability of proliferation/survival transcripts bearing m6A and subsequently leads to increased protein synthesis. Our findings identify a novel function for the m6A methylation in regulating cell fate decision and demonstrate that dynamic m6A methylome is an additional epigenetic driver of reversible TKI-tolerance state, providing a mechanistic paradigm for drug resistance in cancer.
Bibliographical noteFunding Information:
This work was supported in part by National Cancer Institute (Bethesda, MD) grants R01CA149623 (S.L.), R21CA155915 (S.L.), R03CA186176 (S.L.) and GM071440 (C.H.), and The Hormel Foundation (S.L.); C.H. is an investigator of the Howard Hughes Medical Institute (HHMI). The authors specifically thank Dr. Edward Hinchcliffe and Dr. Margot Cleary at the University of Minnesota for their assistance in proofreading and editing this manuscript. The authors wish to thank the Novartis Pharmaceuticals Corporation for providing financial support and nilotinib supply for the clinical trial.
© 2018, The Author(s).