LC-MSMS of the MHC-I immunopeptidome of AML cell line, THP-1

The hypomethylating agent 5-azacytidine (AZA) is the first-line induction therapy for AML patients unsuitable for intensive chemotherapy. The anti-tumor effect of AZA results in part from T-cell cytotoxic responses against MHC-I-associated peptides (MAPs) deriving from hypermethylated genomic regions such as cancer-testis antigens (CTAs), or endogenous retroelements (EREs). However, clear evidence supporting higher ERE MAPs presentation after AZA treatment in AML is lacking. Interestingly, we find that AZA-mediated DNMT2 inhibition leads to autophagy induction, which is responsible for mitigating ERE MAPs generation. To validate our findings, we examined the immunopeptidome of THP-1 cells treated with AZA combined with autophagy inhibitor, Spautin-1 or decitabine (DAC, non-DNMT2 inhibiting HMA) through a proteogenomic approach.