Zou Meijuan, Wang Fang, Jiang Aiqin, Xia Anliang, Kong Siya, Gong Chun, Zhu Mingxia, Zhou Xin, Zhu Jun, Zhu Wei, Cheng Wenfang
Department of Pharmacology, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, China.
Department of Cardiology, First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
Helicobacter. 2017 Apr;22(2). doi: 10.1111/hel.12348. Epub 2016 Aug 5.
Helicobacter pylori infection is the main cause of chronic gastritis, peptic ulcer, and gastric cancer. Tip-α is a newly identified carcinogenic factor present in H. pylori. TRAF3 can activate NF-κB by both canonical and noncanonical signaling pathways. In this study, we found that the expression of TRAF3 and NF-κB was upregulated, while microRNA-3178 (miR-3178) was decreased in H. pylori-positive gastric tissues but not in H. pylori-negative tissues.
GES-1 cells were incubated with 12.5 μg/mL recombinant Tip-α (rTip-α) in RPMI1640 for 2 hours. After another 24 hours, the supernatant medium was designed as inflammatory-conditioned medium (ICM) and that from the untreated control cells was designed as untreated control medium. The release of proinflammatory cytokines from GES-1 cells and proliferation of gastric cancer cells was determined by ELISA and CCK-8 kits. Cells were transfected with the mimic, inhibitor, negative control of miR-3178, or TRAF3 siRNA control siRNA. The medium was then replaced with RPMI1640, 12.5 μg/mL rTip-α, and collected, and the total cellular RNA and protein were extracted for the following detection.
MiR-3178 mimic prevented the increasement of TRAF3 and hence decreased activation of NF-κB signals, whereas miR-3178 inhibitor could not, in GES-1 cells with Tip-α treatment. The condition medium from miR-3178 mimic transfected GES-1 cells could inhibit proliferation and induce apoptosis of inflammation-related gastric cancer cells SGC7901 and MGC803 by decreasing the production of inflammatory cytokines TNF-α and IL-6, which were secreted by GES-1 cells.
Taken all together, Tip-α might activate NF-κB to promote inflammation and carcinogenesis by inhibiting miR-3178 expression, which directly targeting TRAF3, during H. pylori infection in gastric mucosal epithelial cells.
幽门螺杆菌感染是慢性胃炎、消化性溃疡和胃癌的主要病因。Tip-α是幽门螺杆菌中一种新发现的致癌因子。TRAF3可通过经典和非经典信号通路激活NF-κB。在本研究中，我们发现，在幽门螺杆菌阳性的胃组织中TRAF3和NF-κB的表达上调，而微小RNA-3178（miR-3178）表达降低，但在幽门螺杆菌阴性组织中并非如此。
将GES-1细胞在含12.5μg/mL重组Tip-α（rTip-α）的RPMI1640培养基中孵育2小时。再过24小时后，将上清培养基设为炎性条件培养基（ICM），未处理的对照细胞的上清培养基设为未处理对照培养基。采用ELISA和CCK-8试剂盒检测GES-1细胞促炎细胞因子的释放及胃癌细胞的增殖情况。用miR-3178的模拟物、抑制剂、阴性对照或TRAF3 siRNA对照siRNA转染细胞。然后将培养基换成含12.5μg/mL rTip-α的RPMI1640培养基，收集细胞，提取总细胞RNA和蛋白质用于后续检测。
在经Tip-α处理的GES-1细胞中，miR-3178模拟物可阻止TRAF3的增加，从而降低NF-κB信号的激活，而miR-3178抑制剂则不能。转染miR-3178模拟物的GES-1细胞的条件培养基可通过降低GES-1细胞分泌的炎性细胞因子TNF-α和IL-6的产生，抑制炎症相关胃癌细胞SGC7901和MGC803的增殖并诱导其凋亡。
综上所述，在胃黏膜上皮细胞幽门螺杆菌感染期间，Tip-α可能通过抑制直接靶向TRAF3的miR-3178表达来激活NF-κB，从而促进炎症和致癌作用。
