Gastric cancer’s bad incidence, prognosis, cellular and molecular heterogeneity amongst others make this disease a major health issue worldwide. Understanding this affliction is a priority for proper patients’ management and for the development of efficient therapeutical strategies. This review gives an overview of major scientific advances, made during the past 5-years, to improve the comprehension of gastric adenocarcinoma. A focus was made on the different actors of gastric carcinogenesis, including, Helicobacter pylori cancer stem cells, tumour microenvironment and microbiota. New and recent potential biomarkers were assessed as well as emerging therapeutical strategies involving cancer stem cells targeting as well as immunotherapy. Finally, recent experimental models to study this highly complex disease were discussed, highlighting the importance of gastric cancer understanding in the hard-fought struggle against cancer relapse, metastasis and bad prognosis.

Helicobacter pylori infection, the main risk factor for gastric cancer (GC), leads to an epithelial–mesenchymal transition (EMT) of gastric epithelium contributing to gastric cancer stem cell (CSC) emergence. The Hippo pathway effectors yes-associated protein (YAP) and transcriptional co-activator with PDZ binding motif (TAZ) control cancer initiation and progression in many cancers including GC. Here, we investigated the role of TAZ in the early steps of H. pylori-mediated gastric carcinogenesis. TAZ implication in EMT, invasion, and CSC-related tumorigenic properties were evaluated in three gastric epithelial cell lines infected by H. pylori. We showed that H. pylori infection increased TAZ nuclear expression and transcriptional enhancer TEA domain (TEAD) transcription factors transcriptional activity. Nuclear TAZ and zinc finger E-box-binding homeobox 1 (ZEB1) were co-overexpressed in cells harboring a mesenchymal phenotype in vitro, and in areas of regenerative hyperplasia in gastric mucosa of H. pylori-infected patients and experimentally infected mice, as well as at the invasive front of gastric carcinoma. TAZ silencing reduced ZEB1 expression and EMT phenotype, and strongly inhibited invasion and tumorsphere formation induced by H. pylori. In conclusion, TAZ activation in response to H. pylori infection contributes to H. pylori-induced EMT, invasion, and CSC-like tumorigenic properties. TAZ overexpression in H. pylori-induced pre-neoplastic lesions and in GC could therefore constitute a biomarker of early transformation in gastric carcinogenesis.

Aim:Helicobacter pylori infection is a worldwide infection, its eradication rates with conventional therapies have fallen to unacceptable levels. In this context we were interested in metformin, to determine its effect on H. pylori growth. Materials & methods: Antimicrobial susceptibility tests and survival curves were performed in vitro and a H. pylori-infected mice model was used to determine metformin effect in vivo. Results:Helicobacter pylori survival and growth were decreased in presence of metformin. Furthermore, metformin-treated mice had significantly less bacteria in their stomach than the untreated mice. Conclusion: Our work is the first to demonstrate a direct antimicrobial effect of metformin on H. pylori, indicating that this molecule has not yet revealed its full potential.