Long non-coding RNA THRIL regulates Helicobacter pylori CagA induced-inflammation by inhibition of NF-kB translocation

Abstract

The most obvious cause of gastritis and gastric cancer is known as Helicobacter pylori (H. pylori) infection and cytotoxin-associated gene A (CagA). Nevertheless, less is known about what is causing the H. pylori optionally gastric cancer. Recently, long non-coding RNA is interestingly emerged to be associated with regulation of the immune response by pathogen. Moreover, the innate immune response-related lncRNAs have demonstrated to regulate pro-inflammatory cytokines by interacting with RNA binding protein. THRIL (TNFα and hnRNPL related immunoregulatory lincRNA) is first reported to regulate lipopolysaccharide induced tumor necrosis factor alpha (TNFα) by interacting with heterogenous nuclear ribonucleoprotein L (hnRNPL).

We investigated the roles of THRIL in H. pylori infection. The expression of THRIL was determined by qRT-PCR in normal gastric cell line GES-1 cell and a variety of human cancer cell lines. Down regulation of THRIL was confirmed by processing two different siRNAs. For pathogen infection, H. pylori strains 60190 (CagA+), 8822 (CagA-) and CagA (an isogenic mutant of 60190 lacking CagA) were used. We measured TNFα secretion by H. pylori infection using ELISA analysis. We dissected canonical NF-kB pathway by H. pylori infection after treatment with siRNAs targeting THRIL.

When compared to gastric normal epithelial cell, expression of THRIL was up-regulated in various human cancer cell lines. 8822 (CagA-) and CagA did not influence the levels of TNFα, IL-8 and THRIL. Only 60190 (CagA+) induced TNFα and IL-8 in GES-1 cell and inversely down-regulated THRIL. Knockdown of hnRNPL also resulted in significant decrease in TNFα and IL-8 induction caused by CagA-positive H. pylori without alteration of THRIL. Down regulation of THRIL by siRNA decreased mRNA expression of TNFα and IL-8 in both basal status and CagA-positive H. pylori infection. Also double knockdown of THRIL and hnRNPL attenuated TNFα induction by CagA-positive H. pylori.

Taken together, THRIL and hnRNPL regulated CagA-induced inflammation by NF-kB dependent way.