骨髓增生异常综合征（MDS）向急性髓系白血病（AML）的转变提出了重大的临床挑战。 H3 在赖氨酸 27 (H3K27me3) 甲基化酶和去甲基化酶途径上的三甲基化参与了 MDS 进展的调节。本研究调查了 MEK/ERK 和 PI3K/AKT 通路在 MDS 向 AML 转化中的功能机制。首先建立 MDS-AML 小鼠和 SKM-1 细胞模型，然后使用 MEK/ERK 通路抑制剂 U0126、PI3K/AKT 通路抑制剂 Ly294002 或其组合进行治疗。使用蛋白质印迹分析测定 H3K27me3 甲基化酶、zeste 同源增强子 (EZH)1、EZH2、去甲基化酶 Jumonji 结构域蛋白 3 (JMJD3) 和 X 染色体上普遍转录的四肽重复序列 (UTX) 和 H3K27me3 蛋白水平。使用 CCK-8、流式细胞术、EdU 和集落形成测定来评估细胞活力、周期分布和增殖。测定临床样本和建立的模型中的 ERK 和 AKT 磷酸化水平，并评估 SKM-1 细胞行为。测量了 H3K27me3 甲基化酶和去甲基化酶以及远端同源盒 5 (DLX5) 的水平。结果显示，MDS 和 MDS-AML 患者以及小鼠模型中的 ERK 和 AKT 磷酸化水平升高。使用 MEK/ERK 通路抑制剂 U0126 和 PI3K/AKT 通路抑制剂 Ly294002 治疗，可有效抑制 MDS-AML 小鼠的 ERK 和 AKT 磷酸化。据观察，用 U0126/Ly294002 治疗的 MDS 小鼠表现出向 AML 的转化减少、疾病转化延迟并提高存活率。用 U0126/Ly294002 处理 SKM-1 细胞会导致细胞活力和增殖降低，并通过抑制 ERK/PI3K 磷酸化增加细胞周期停滞。此外，U0126/Ly294002处理下调了EZH2/EZH1表达，并上调了JMJD3/UTX表达。当 SKM-1 细胞中 EZH2/EZH1 过表达或 JMJD3/UTX 受到抑制时，U0126/Ly294002 的作用无效。用U0126/Ly294002处理还导致DLX5启动子区域中的H3K27me3蛋白水平和H3K27me3水平降低，从而导致DLX5表达增加。总体而言，本研究的结果表明，U0126/Ly294002 通过调节 H3K27me3 甲基化酶和去甲基化酶的水平以及调节 DLX5 转录和表达来参与 MDS-AML 转化。

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.