Fig. 7
Clinical implications of FTO-mediated m6A demethylation in leukemia. a Upper, graphs are the quantification of clone sizes (n = 5); lower, representative images of parental and resistant clones (n = 5) from primary cells of an AML or CML patient. b CCK-8 assays in AML and CML parental and resistant clones treated with nilotinib for 72 h. c CCK-8 assays in AML and CML resistant clones incubated with 25 µM rhein for 6 h followed by nilotinib treatment for another 72 h. d Western blotting of AML and CML clones. The protein lysates are the pool of 5 clones. e Dotblotting of AML and CML parental and resistant clones (pool of 5 clones). f qPCR of AML and CML parental and resistant clones. g qPCR of AML and CML resistant clones (n = 5) treated with 25 µM rhein for 48 h. h qPCR of RNA extracted from AML patients (n = 14) receiving nilotinib therapy. i Dotblotting of RNA extracted from nilotinib-treated AML patients (n = 5). Left, the image of m6A dotblotting; right, graph indicates the quantification of dot intensities. j Schematic model illustrating the role of the FTO-m6A axis in mediating TKI resistance. (i) The levels of FTO expression/m6A abundance in cancer cells define the epigenetically heterogeneous (het) states where cells are genetically homogeneous (hom) in terms of targeting RTKs (KIT, FLT3, BCR/ABL). (ii) Cells with low FTO/high m6A are sensitive to TKI-induced killing. (iii) Cells carrying moderately high FTO/low m6A survive initially, and establish TKI resistance eventually when the FTO/m6A functions are further enhanced by chronic TKI exposure. (iv) Restoring m6A methylation by FTO inhibition resensitizes resistant cells to TKIs. Data in CCK-8 assays represent two independent experiments with 8 duplicates; Data are mean ± SD; *p < 0.05, **p < 0.01. See also Figure S8 and Table S3
