为了探讨沉默DNA甲基转移酶1（DNA methyltransferase 1, DNMT1）增强NK-92对Jurkat细胞杀伤作用及机制，检测2020年1月-2021年12月35例急性淋巴细胞白血病（acute lymphoblastic leukemia, ALL）患者骨髓标本的DNMT1水平。si-DNMT1被转染至NK-92细胞，并与Jurkat细胞共培养，乳酸脱氢酶（lactate dehydrogenase, LDH）法检测对Jurkat细胞的杀伤作用，流式细胞术检测Jurkat细胞凋亡及NKG2D膜表达。ELISA检测细胞因子IFN-γ水平，Western blotting测定NK-92细胞Syk、ZAP70、p-Syk、p-ZAP70、穿孔素、颗粒酶B表达。结果显示，ALL患者DNMT1水平明显高于对照组（P＜0.05）；DNMT1对ALL具有诊断价值（AUC：0.692，95%CI：0.533-0.851，P=0.033）。高DNMT1组患者PFS明显低于低DNMT1组患者（P＜0.05）。转染si-DNMT1后，NK-92细胞对Jurkat细胞杀伤率、Jurkat细胞凋亡率明显高于si-NC组（P＜0.05），分泌NKG2D，及表达穿孔素、颗粒酶B能力明显升高（P＜0.05）。si-DNMT1组NK-92细胞生成IFN-γ水平明显高于si-NC组（P＜0.05），其p-Syk、p-ZAP70明显高于si-NC组（P＜0.05）。综上，DNMT1在ALL中高表达，沉默DNMT1可增强NK-92细胞对Jurkat细胞杀伤作用，其机制可能与增强NK-92细胞记忆功能、激活Syk/ZAP70通路相关。

This study aimed to investigate the effect and mechanism of silencing DNA methyltransferase 1 (DNMT1) on the killing effect of NK-92 on Jurkat cells. The DNMT1 expression in the bone marrow of 35 patients with acute lymphocyte leukemia (ALL) from January 2020 to December 2021 were measured. The si-RNA-DNMT1 was transfected into NK-92 cells and co-cultured with Jurkat cells. The killing effect on Jurkat cells was detected by lactate dehydrogenase (LDH) method, and the apoptosis and membrane NKG2D of Jurkat cells were detected by flow cytometry. The levels of IFN-γ were estimated by ELISA. The expressions of Syk, ZAP70, p-Syk, p-ZAP70, perforin and granzyme B in NK-92 cells were measured by Western blotting. The results showed that the level of DNMT1 was increased in patients with ALL compared to the control group (P<0.05), and it was of diagnostic value for ALL (AUC: 0.692, 95% CI: 0.533-0.851, P=0.033). The progression free survival of patients with high DNMT1 was significantly lower than those with low DNMT1 (P<0.05). NK-92 transfected with si-RNA-DNMT1 showed a higher killing rate and cell apoptosis compared to those of the si-NC group (P<0.05), along with the enhanced ability to secrete NKG2D and express perforin and granzyme B (P<0.05). The IFN-γ level of NK-92 transfected with si-RNA-DNMT1 was significantly higher than that in the si-NC group (P<0.05). The p-Syk and p-ZAP70 protein levels of si-RNA-DNMT1 transfected NK-92 were also significantly higher than those in the si-NC group (P<0.05). In conclusion, DNMT1 expression increases in ALL and silencing DNMT1 promotes the killing ability of NK-92 cells on Jurkat cells. The mechanism may be related to enhanced function of NK-92 cells and activation of Syk/ZAP70 pathway.