This result, suggesting the role of Cx43 in VacA-induced cell death, was corroborated by the evidence that AZ-521 cells silenced for Cx43 were less efficiently killed by VacA. Moreover, a correlation existed between the reduced sensitivity of three Olaparib cell types (HeLa, AGS and RK13) and the absence of Cx43 in the same cells. However, the fact that the extent of sensitivity to VacA

varied, even if Cx43 was undetectable in all of the tested cell lines, suggests that factors other than Cx43 are probably involved. Another study [10] demonstrated that the apoptosis induced by VacA and potentiated by ammonium chloride, as reported elsewhere, involves endoplasmic reticulum (ER) stress. In particular, CHOP, a key mediator in the ER-stress-induced cell death and Bax activation, was found upregulated in cells exposed to VacA plus ammonium chloride and its presence was essential for activating KU-57788 nmr the apoptotic program. Moreover, all other components involved in the canonical ER-stress-induced signalling cascade were activated or induced by VacA and were required for the execution of apoptosis. Although it is established that the activation of the pro-apoptotic protein Bax has a pivotal role in the VacA-induced apoptosis, the mechanism by which this activation occurs is not fully understood: The results of Akazawa et al.

[9] add one more piece to the complicated puzzle of VacA-induced cell death. Among the virulence factors produced by H. pylori, in the recent past, the γ-glutamyl-transpeptidase (GGT) has gained increasing

attention. This enzyme, which is expressed and released by all strains, acts by metabolizing extracellular glutathione (GSH) leading to H2O2 production [10]. A body of evidence supports the idea that GGT is involved in many aspects of pathogenesis during the H. pylori infection. Indeed, beyond its undoubted contribution during the stage of colonization, GGT acts on several selleck chemicals pathways in the host cells, including the induction of apoptosis in epithelial cells. The latter event has been shown to occur both in vitro and in vivo following H. pylori infection and has been suggested to be important in the early stages of cancerogenesis. Recently, Valenzuela et al. [11] showed that survivin, a member of the inhibitor of apoptosis (IAP) family of proteins, is expressed less in the mucosa of H. pylori-infected patients in contrast to healthy subjects, and they found a clear-cut correlation between survivin downregulation and increased cell death of gastric epithelial cells exposed to H. pylori. In a more recent study, the same group demonstrated in two different kinds of gastric epithelial cells (MKN45 and AGS) infected by H. pylori that GGT is responsible for the survivin loss: the virulence factor promotes the proteasomal degradation of the protein through a mechanism requiring its GGT activity [12].