Mass spectrometry-based proteomics to study gastric carcinogenesis: pathophysiological molecular characterization

Background Gastric cancer (GC) remains a major global health challenge, ranking as the fifth most common malignancy. This study employs a proteomic approach to identify stage-specific proteomic signatures at different stages of gastric carcinogenesis, including chronic gastritis (CG), intestinal metaplasia and low-grade dysplasia (IM-LGD) and advanced stages such as early GC (EGC) and GC, to better understand GC pathogenesis. Methods The EpiGASTRIC/EDGAR study is a prospective, multicentre, population-based study across Spain. Forty-six patients and seventy-two human gastric tissue samples were employed for proteomic analysis using mass spectrometry: 10 were controls (normal gastric mucosa), 10 CG, 7 IM-LGD, 10 EGC and 9 GC. Samples were collected from lesional (L) and non-lesional (NL) areas in IM-LGD, EGC, and GC. Total and phospho-specific levels of p65 NF-κB and p38MAPK were measured using western blot. Results Across the 3.272 quantified proteins, distinct subsets of proteins displayed differential modulation depending on the pathological or non-pathological nature of the tissue. Pathways related to electron transport, oxidative phosphorylation, and mitochondrial import exhibited an inhibitory trend across all cohorts. In contrast, specific pathways such as the degradation of the extracellular matrix and microautophagy signaling were modulated only in the malignancy stages. Western blot revealed coordinated activation of p65 NF-kB and p38 MAPK pathways, particularly in the transition from CG to IM-LGD to EGC. The observation of elevated pp38 levels in IM-LGD-L, unlike pp65, suggests a distinct role for these kinases in areas of cellular transformation. Conclusions Distinct activation patterns of NF-κB p65 and p38MAPK were observed, suggesting they are crucial targets in gastric carcinogenesis. Further research is needed to elucidate how their post-translational modifications drive malignant transformation. Trial registration: clinicaltrials.gov (NCT05551416; first posted September 22 2022).