Objective: This study aimed to explore the synergistic effect and underlying mechanism of azacitidine (AZA) in combination with homoharringtonine (HHT) in acute myeloid leukemia (AML) . Methods: The synergistic effects of AZA and HHT were examined by cell proliferation, apoptosis, and colony formation assays. The synergistic effects were calculated using the combination index (CI) , and the underlying mechanisms were explored using RNA sequencing, pathway inhibitors, and gene knockdown approaches. Results: Compared with the single-drug controls, AZA and HHT combination significantly induced cell proliferation arrest and showed a synergistic effect with CI < 0.9 in AML cells. In the combination group versus the single-drug controls, colony formation was significantly decreased, whereas apoptosis was significantly increased in U937 (P<0.001) and MV4-11 (P<0.001) cells. AZA and HHT combination activated the integrated stress response (ISR) signaling pathway and induced DDIT3-PUMA-dependent apoptosis in cells. Furthermore, it remarkably downregulated the expression of c-MYC. The combination also activated c-MYC/DDIT3/PUMA-mediated ISR signaling to induce synergy on apoptosis. The synergy of AZA+HHT on apoptosis was induced by activating c-MYC/DDIT3/PUMA-mediated ISR signaling. Conclusion: The combination of AZA and HHT exerts synergistic anti-AML effects by inhibiting cellular proliferation and promoting apoptosis through activation of the ISR signaling pathway via the c-MYC/DDIT3/PUMA axis.
目的： 探索阿扎胞苷（AZA）联合高三尖杉酯碱（HHT）治疗急性髓系白血病（AML）的协同效应及其分子机制。 方法： 采用细胞增殖、凋亡和克隆形成实验研究AZA联合HHT在AML中协同效应并计算两药协同效应指数（CI），通过转录组测序、通路抑制剂和基因敲降等方法，探索两药的协同机制。 结果： 与单药相比，AZA+ HHT可显著抑制AML细胞增殖，并具有显著的协同效应（U937、MV4-11和KG-1细胞中CI值均小于0.9）；AZA+HHT能显著抑制U937（P<0.001）和MV4-11（P<0.001）细胞的克隆形成，并显著促进U937（P<0.001）和MV4-11（P<0.001）细胞凋亡。AZA联合HHT通过激活整合应激反应（ISR）信号通路介导DDIT3-PUMA依赖的AML细胞凋亡。AZA联合HHT可明显下调c-MYC蛋白，通过激活ISR信号通路，调控c-MYC/DDIT3/PUMA轴，促进细胞凋亡发挥协同抗AML作用。 结论： AZA联合HHT通过激活ISR信号通路，调控c-MYC/DDIT3/PUMA轴，抑制细胞增殖和促进细胞凋亡，发挥协同抗AML作用。.
Keywords: Azacitidine; Homoharringtonine; Leukemia, myeloid, acute; Synergistic effect.