EBV-BZLF1通过激活PI3K/AKT信号通路促进胃癌细胞生长

Epstein-Barr virus BZLF1 promotes the growth of gastric cancer cells through activation of the PI3K/AKT signaling pathway

目的:明确EB病毒(Epstein-Barr virus,EBV)BZLF1基因(EBV-BZLF1)对EB的分子机制。方法:运用过表达BZLF1的慢病毒感染胃癌细胞系AGS和HGC27,分别采用CCK8、细胞凋亡检测、细胞迁移和侵袭实验及Western blot法检测细胞的增殖能力、细胞凋亡与迁移侵袭能力及细胞信号通路变化情况。将过表达BZLF1的胃癌细胞HGC27注射于非肥胖糖尿病/重症联合免疫缺陷(NOD/SCID)小鼠背部皮下构建移植瘤模型,观察BZLF1对肿瘤生长的影响。结果:过表达BZLF1的慢病毒感染组AGS-BZLF1与HGC27-BZLF1相比亲本细胞,细胞中BZLF1蛋白表达明显上调;体外细胞增殖与小鼠体内成瘤能力均显著增强(P<0.05);细胞凋亡受到BZLF1蛋白的抑制,其中AGS-BZLF1和HGC27-BZLF1凋亡率为(2.40±0.14)%和(3.90±0.14)%,显著低于AGS和HGC细胞的(5.75±0.35)%和(9.70±0.42)%(P<0.05);但细胞迁移和侵袭能力无明显改变。深入分子机制研究发现,BZLF1表达上调后,PI3K/AKT信号通路明显激活,表现为pAKT和pS6蛋白表达上调。使用BEZ235抑制剂阻断PI3K/AKT信号通路后,HGC27-BZLF1和AGS-BZLF1细胞的生长均受到抑制。结论:EBV-BZLF1可通过激活PI3K/AKT信号通路促进胃癌细胞生长,靶向PI3K/AKT通路抑制剂或可成为EBV阳性胃癌的治疗选择。

Objective: To explore the effect of the Epstein-Barr virus (EBV) BZLF1 gene on the biological behavior of EBV-negative gastric cancer cells and the underlying molecular mechanism. Methods: Lentiviral overexpressing BZLF1 was used to infect AGS and HGC27 gastric cancer cell lines. And the cell proliferation, apoptosis and migration invasive ability, and expression changes of cell signaling pathway were detected by CCK8 assay, apoptosis detection, migration and invasion assay, as well as western blot. HGC27 cells overexpressing BZLF1 were injected into the dorsal of NOD/SCID mice to construct xenografts, and the effect of BZLF1 on tumor growth was observed. Results: The expression of BZLF1 protein was significantly up-regulated in AGS-BZLF1 and HGC27-BZLF1 infected by over-expressing BZLF1 lentivirus. The cell proliferation in vitro and the tumorigenic ability in mice were significantly increased (P<0.05). Apoptosis was inhibited by BZLF1 protein, and the apoptotic rate of AGS-BZLF1 and HGC27-BZLF1 was (2.40±0.14)% and (3.90±0.14)%, which was significantly lower than (5.75±0.35)% and (9.70 ± 0.42)% of AGS and HGC cells (P<0.05);however, there was no significant change in cell migration and invasion ability. In-depth molecular mechanism studies found that PI3K/AKT signaling pathway was significantly activated with enhanced pAKT and pS6 expression. After blocking the PI3K/AKT signaling pathway with BEZ235 inhibitor, the growth of HGC27-BZLF1 and AGS-BZLF1 cells was inhibited. Conclusions: EBV BZLF1 may promote the growth of gastric cancer cells by activating the PI3K/AKT signaling pathway and targeting PI3K/AKT pathway inhibitors, and serve as a promising treatment option for EBV-associated gastric carcinoma.