Proteomics-Based Identification and Analysis of Proteins Associated with Helicobacter pylori in Gastric Cancer

Abstract

Helicobacter pylori (H. pylori) is a spiral-shaped Gram-negative bacterium that causes the most common chronic infection in the human stomach. Approximately 1%-3% of infected individuals develop gastric cancer. However, the mechanisms by which H. pylori induces gastric cancer are not completely understood. The available evidence indicates a strong link between the virulence factor of H. pylori, cytotoxin-associated gene A (CagA), and gastric cancer. To further characterize H. pylori virulence, we established three cell lines by infecting the gastric cancer cell lines SGC-7901 and AGS with cagA+ H. pylori and transfecting SGC-7901 with a vector carrying the full-length cagA gene. We detected 135 differently expressed proteins from the three cell lines using proteome technology, and 10 differential proteins common to the three cell lines were selected and identified by LC-MS/MS as well as verified by western blot: β-actin, L-lactate dehydrogenase (LDH), dihydrolipoamide dehydrogenase (DLD), pre-mRNA-processing factor 19 homolog (PRPF19), ATP synthase, calmodulin (CaM), p64 CLCP, Ran-specific GTPase-activating protein (RanGAP), P43 and calreticulin. Detection of the expression of these proteins and genes encoding these proteins in human gastric cancer tissues by real-time PCR (RT-qPCR) and western blot revealed that the expression of β-ACTIN, LDH, DLD, PRPF19 and CaM genes were up-regulated and RanGAP was down-regulated in gastric cancer tissues and/or metastatic lymph nodes compared to peri-cancerous tissues. High gene expression was observed for H. pylori infection in gastric cancer tissues. Furthermore, the LDH, DLD and CaM genes were demethylated at the promoter -2325, -1885 and -276 sites, respectively, and the RanGAP gene was highly methylated at the promoter -570 and -170 sites in H. pylori-infected and cagA-overexpressing cells. These results provide new insights into the molecular pathogenesis and treatment targets for gastric cancer with H. pylori infection.

Analysis of virulence diversity of 73 Helicobacter�pylori strains isolated in Guizhou province, China

“…In the present study, it was shown that cagA genotypes were detected in all strains in Guizhou province. In another study in this region, Zhou et al reported that 30 H. pylori strains isolated from gastric cancer were cagA-positive, with cagA having a positive rate of 100% (35), which was consistent with the results of the present study. The vacA genotypes also vary geographically.…”

“…The present study did not find an association between H. pylori virulence diversity and clinical disease outcomes in the Guizhou region. Zhou et al reported that H. pylori infection may induce the demethylation of lactate dehydrogenase, dihydrolipoamide dehydrogenase and calmodulin genes, and increase methylation of the Ran-specific GTPase-activating protein gene, which leads to dysfunctional gene expression in gastric cancer tissues and cells (35). A number of reports have shown that infection with Table V.…”

Genome-wide DNA copy number analysis in clonally expanded human ovarian cancer cells with distinct invasive/migratory capacities

“…PRPF19 (pre-mRNA-processing factor 19) is a U-box-containing E3 ubiquitin ligase and is involved in the DNA damage response [ 47 ]. PRPF19 expression was found to be greater in gastric cancer tissues and/or metastatic lymph nodes than in peri-cancerous tissues [ 48 ]. Another report indicated that PRPF19 expression was elevated in most hepatocellular carcinoma tissues and cell lines, and its overexpression correlated positively with vascular invasion and tumor capsule breakthrough, probably through the p38 mitogen-activated protein kinase/twist1 pathway [ 49 ].…”

Recent Advances of Functional Proteomics in Gastrointestinal Cancers- a Path towards the Identification of Candidate Diagnostic, Prognostic, and Therapeutic Molecular Biomarkers

“…Several proteomics studies focusing on PTMs in GI cancers have been published so far; including protein phosphorylation [ 10 ], glycosylation [ 11 ], acetylation [ 12 ], methylation [ 13 ] and ubiquitination [ 14 ]. Protein phosphorylation and glycosylation in particular have been extensively studied in GI cancers because of their key role in regulating a wide range of cellular signaling pathways associated with initiation, promotion and progression of the disease.…”