[METTL3-mediated m6A modification promotes FOXO3 expression and anthracycline resistance in acute myeloid leukemia cells through autophagy regulation].

Objectives: To investigate the role of METTL3 and FOXO3 in anthracycline resistance in acute myeloid leukemia (AML) cells.

Methods: Methylated RNA immunoprecipitation sequencing (MeRIP-seq) and transcriptome sequencing (RNA-seq) were performed in anthracycline-resistant and sensitive HL60 and K562 cells with lentivirus-mediated knockdown or overexpression of METTL3 and FOXO3. TCGA and GSE6891 datasets were used for analysis of the clinical and gene expression data of AMI patients. FOXO3 expressions at the mRNA and protein levels in the transfected cells were detected with RT-qPCR and Western blotting, and the changes in cell proliferation and apoptosis were evaluated using CCK8 assay and flow cytometry; the expression of m⁶A-modified mRNA and mRNA stability of FOXO3 was detected analyzed using MeRIP-qPCR and RT-qPCR. Functional enrichment analysis of the differential genes in the transfected cells was performed.

Results: Differential gene analysis in anthracycline-resistant versus sensitive AML cells and in cells with METTL3 knockdown revealed the enrichment in FoxO and autophagy pathways (P<0.05), and the anthracycline-resistant cells showed significantly increased m⁶A modification of FOXO3. FOXO3 expression was positively correlated with METTL3 expression. METTL3 knockdown significantly reduced FOXO3 mRNA stability and its protein levels in anthracycline-resistant AML cells, which exhibited higher m6A-modified FOXO3 expression levels than their sensitive counterparts. Database analysis, Kaplan-Meier analysis and RT-qPCR results suggested that a high FOXO3 expression was associated with a poor prognosis of AML patients. In anthracycline-resistant AML cells expressing higher FOXO3 levels than the sensitive cells, lentivirus-mediated overexpression of FOXO3 significantly enhanced cell proliferation and suppressed cell apoptosis. Inhibiting autophagy using an autophagy inhibitor (Baf.A1) obviously enhanced the inhibitory effect of adriamycin on resistant AMI cells and cells overexpressing FOXO3.

Conclusions: METTL3 promotes FOXO3 expression via m6A modification, and FOXO3-driven autophagy contributes to anthracycline resistance in AML cells by enhancing cell proliferation and suppressing cell apoptosis.