Helicobacter pylori VacA toxin up-regulates vascular endothelial growth factor expression in MKN 28 gastric cells through an epidermal growth factor receptor-, cyclooxygenase-2-dependent mechanism.
OBJECTIVE
Helicobacter pylori causes gastric damage and is involved in gastric carcinogenesis. Vascular endothelial growth factor (VEGF) plays a major role in gastric mucosa repair and is overexpressed in gastric cancer. We investigated: (a) whether H. pylori, and in particular H. pylori VacA toxin, affected VEGF expression in gastric epithelial cells in culture; and (b) the signal transduction pathway involved in any effect exerted by H. pylori.


METHODS
MKN-28 cells were incubated with uninoculated BCF (control) or with BCF obtained from VacA-producing wild-type H. pylori 60190 strain or from its isogenic mutant 60190:v1, specifically lacking vacA gene in the presence or absence of ZD 1839, a selective inhibitor of the epidermal growth factor receptor (EGFR) tyrosine kinase, PD098059, a selective inhibitor of mitogen-activated protein (MAP)/extracellular signal-regulated kinase (ERK) kinase, the kinase responsible for ERK phosphorylation, or SC-236, a selective inhibitor of cyclooxygenase (COX)-2 for 24-48 h.


RESULTS
(a) Toxigenic H. pylori up-regulated VEGF mRNA and protein expression and caused a 2.5-fold increase in VEGF release compared with control, whereas nontoxigenic H. pylori did not; (b) H. pylori VacA toxin-induced up-regulation of VEGF was counteracted by selective inhibition of EGFR tyrosine kinase; (c) toxigenic H. pylori activated the ERK/MAP kinase cascade, and inhibition of MAP kinase activation counteracted H. pylori-induced VEGF up-regulation; (d) toxigenic H. pylori up-regulated COX-2 expression, and this effect was counteracted by blockade of EGFR tyrosine kinase; and (e) COX-2 selective inhibition counteracted H. pylori-induced up-regulation of VEGF.


CONCLUSIONS
(a) H. pylori up-regulates VEGF expression in gastric epithelial cells; and (b) this effect is specifically related to VacA toxin and seems to depend on the activation of an EGFR-, MAP kinase-, and COX-2-mediated pathway.
Caputo
Rosa
R
Dipartimento di Internistica Clinica e Sperimentale-Cattedra di Gastroenterologia, Seconda Università di Napoli, Napoli, Italy.
Tuccillo
Concetta
C
Manzo
Barbara A
BA
Zarrilli
Raffaele
R
Tortora
Giampaolo
G
Blanco
Camillo Del Vecchio
Cdel V
Ricci
Vittorio
V
Ciardiello
Fortunato
F
Romano
Marco
M
D001426:Bacterial Proteins / Q000502:physiology*; D051546:Cyclooxygenase 2; D066246:ErbB Receptors / Q000502:physiology*; D000077156:Gefitinib; D016480:Helicobacter pylori / Q000472:pathogenicity*; D006801:Humans; D007527:Isoenzymes / Q000502:physiology*; D020935:MAP Kinase Signaling System / Q000502:physiology; D008565:Membrane Proteins; D011451:Prostaglandin-Endoperoxide Synthases / Q000502:physiology*; D011799:Quinazolines / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D015398:Signal Transduction; D013274:Stomach Neoplasms / Q000378:metabolism* / Q000382:microbiology*; D015854:Up-Regulation; D042461:Vascular Endothelial Growth Factor A / Q000096:biosynthesis* / Q000235:genetics
D001426:Bacterial Proteins; D007527:Isoenzymes; D008565:Membrane Proteins; D011799:Quinazolines; D012333:RNA, Messenger; C074689:VacA protein, Helicobacter pylori; D042461:Vascular Endothelial Growth Factor A; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D066246:ErbB Receptors; D000077156:Gefitinib