Helicobacter, gamma-glutamyltransferase and cancer: further intriguing connections.

Virulence of Helicobacter pylori, Helicobacter suis and other bacteria appears to be partly mediated through a release of gamma-glutamyltransferase (GGT), an enzyme activity capable of promoting biochemical reactions ultimately resulting in damage to gastric epithelium and suppression of immune response. Recently published studies show that secretion of bacterial GGT occurs in the form of exosome-like vesicles. Very similar GGT-rich exosomes have been described to originate from human cancer cells, and the hypothesis is thus forwarded that in the resistant and invasive phenotype of malignant cells such vesicular/exosomal GGT may play roles akin to those described for Helicobacter infection, thus providing a significant contribution to the establishment of cancer metastases.