IL-17A promotes Helicobacter pylori-induced gastric carcinogenesis via interactions with IL-17RC

Gastric cancer (GC) is a common malignancy worldwide, with a major attribution to Helicobacter pylori. Interleukin (IL)-17A has been reported to be up-regulated in serum and tumor of GC patients, but the precise mechanisms underlying its involvement in gastric tumorigenesis are yet to be established. Here, we investigated the roles of IL-17A in the pathogenesis of H. pylori-induced GC.

GC was induced in IL-17A knockout (KO) and wild-type (WT) mice via N-methyl-N-nitrosourea (MNU) treatment and H. pylori infection. At 50 weeks after treatment, gastric tissues were examined by histopathology, immunohistochemistry, and immunoblot analyses. In vitro experiments on the human GC cell lines were additionally performed to elucidate the underlying mechanisms.

Deletion of IL-17A suppressed MNU and H. pylori-induced gastric tumor development accompanied by a decrease in gastric epithelial cell growth, oxidative stress, and expression of gastric epithelial stem cells markers. In AGS cells, recombinant human IL-17A (rhIL-17A) inhibited apoptosis and G1/S phase transition arrest while promoting reactive oxygen species production, sphere formation ability of cancer stem cells (CSC), and expression of stemness-related genes. In addition, rhIL-17A induced expression of IL-17RC, leading to NF-κB activation and increased NADPH oxidase 1 (NOX1) levels. Inhibition of NOX1 with GKT136901 attenuated rhIL-17A-mediated elevation of GC cell growth, ROS generation, and CSC stemness. Clinically, IL-17RC expressions were significantly upregulated in human GC compared with normal gastric tissues.

Our results suggest that IL-17A promotes gastric carcinogenesis, in part, by regulating IL-17RC/NF-κB/NOX1 pathway, supporting its potential as a target in human GC therapy.