MEK/ERK and PI3K/AKT pathway inhibitors affect the transformation of myelodysplastic syndrome into acute myeloid leukemia via H3K27me3 methylases and de-methylases

The transformation of myelodysplastic syndrome (MDS) into acute myeloid leukemia (AML) poses a significant clinical challenge. The trimethylation of H3 on lysine 27 (H3K27me3) methylase and de-methylase pathway is involved in the regulation of MDS progression. The present study investigated the functional mechanisms of the MEK/ERK and PI3K/AKT pathways in the MDS-to-AML transformation. MDS-AML mouse and SKM-1 cell models were first established and this was followed by treatment with the MEK/ERK pathway inhibitor, U0126, the PI3K/AKT pathway inhibitor, Ly294002, or their combination. H3K27me3 methylase, enhancer of zeste homolog (EZH)1, EZH2, demethylase Jumonji domain-containing protein-3 (JMJD3) and ubiquitously transcribed tetratricopeptide repeat on chromosome X (UTX) and H3K27me3 protein levels were determined using western blot analysis. Cell viability, cycle distribution and proliferation were assessed using CCK-8, flow cytometry, EdU and colony formation assays. The ERK and AKT phosphorylation levels in clinical samples and established models were determined, and SKM-1 cell behaviors were assessed. The levels of H3K27me3 methylases and de-methylases and distal-less homeobox 5 (DLX5) were measured. The results revealed that the ERK and AKT phosphorylation levels were elevated in patients with MDS and MDS-AML, and in mouse models. Treatment with U0126, a MEK/ERK pathway inhibitor, and Ly294002, a PI3K/AKT pathway inhibitor, effectively suppressed ERK and AKT phosphorylation in mice with MDS-AML. It was observed that mice with MDS treated with U0126/Ly294002 exhibited reduced transformation to AML, delayed disease transformation and increased survival rates. Treatment of the SKM-1 cells with U0126/Ly294002 led to a decrease in cell viability and proliferation, and to an increase in cell cycle arrest by suppressing ERK/PI3K phosphorylation. Moreover, treatment with U0126/Ly294002 downregulated EZH2/EZH1 expression, and upregulated JMJD3/UTX expression. The effects of U0126/Ly294002 were nullified when EZH2/EZH1 was overexpressed or when JMJD3/UTX was inhibited in the SKM-1 cells. Treatment with U0126/Ly294002 also resulted in a decreased H3K27me3 protein level and H3K27me3 level in the DLX5 promoter region, leading to an increased DLX5 expression. Overall, the findings of the present study suggest that U0126/Ly294002 participates in MDS-AML transformation by modulating the levels of H3K27me3 methylases and de-methylases, and regulating DLX5 transcription and expression.