TLR2 & TLR4 Signaling Pathways and Gastric Cancer: Insights from Transcriptomics and Sample Validation

Gastric cancer (GC) and chronic gastritis are induced by Helicobacter pylori (H.pylori) in most cases. Pattern recognition receptors (PRRs), especially Toll-like receptors (TLRs), as the first line of defense for pathogen detection, were found to be associated with H. pylori infection and gastric cancer. However, the expression levels of TLRs, especially TLR2 and TLR4 as the main receptors sensed H. pylori, still remain largely ambiguous. Herein, we aimed to investigate the patterns of key transcripts of TLR2 and TLR4 in 100 GC transcriptome data. Additionally, we evaluated TLR2 and TLR4 gene expressions in GC samples obtained from Iranian GC biopsy specimen, in order to validate RNA-seq outputs.

100 runs of GC samples and controls were processed and analyzed using map read to reference test by CLC genomics workbench package.  DGE method was used to distinguish between GC and Ctrl samples in the expression of TLRs and other innate immune molecules. Also using qRT-PCR assay and Pffafle method, transcripts of TLRs molecules for 15 GC and 15 Ctrl samples were analyzed based on analysis of variance and least significant differences. 

The results clearly showed that all signaling pathways molecules  of TLR4, especially, TLR4(P-value = 0.019), NF-κB (P-value = 0.047), IL-1β( P-value = 0.0096), and TNF-α( P-value= 0.048), have up-regulated  in a cancerous condition in different parts and at various stages of gastric cancers.

Totally, this finding confirmed that molecules involved in inflammation including TLR4 and its related pro-inflammatory cytokines play a critical role in the development and progression of GCs.. Accordingly, the controlling of.  H.pylori infection consequently reduce inflammation in the gastric system can play an important role in preventing gastrointestinal disorders.