Novel mechanism of gastric proton pump inhibitor (PPI) : Suppression of Helicobacter-pylori induced angiogenesis and selective induction of apoptosis in gastric cancer cells.

To survival in an ischemic microenvironment with a lower extracellular pH, ability to up-regulate proton extrusion is critical for cancer cell survival. Gastric H+/K+-ATPase exchanges luminal K+ for cytoplasmic H+ and is the enzyme primarily responsible for gastric acidification. On the basis of the fact that blocking the clearance of acidic metabolites are known to induce the cell death, we hypothesized that pantoprazole (PPZ), one of gastric H+/K+-ATPase inhibitors used frequently to treat acid-related diseases, could inhibit growth of tumor cells. And, although activation of mitogen activated protein kinases (MAPKs) by Helicobacter pylori infection is associated with induction of host angiogenesis, which may contribute to H.pylori associated gastric carcinogenesis, the strategy for its prevention has not been identified. As we previously reported a strong inhibitory action of gastric proton pump inhibitors (PPIs) on MAPK extracellular signal regulated kinase (ERK) 1/2 phosphorylation, we investigated whether PPIs could suppress the H.pylori induced angiogenesis via inhibition of MAPK ERK1/2. To detect PPZ-induced apoptosis, we performed that Genomic DNA fragmentation, terminal deoxynucleotidyl transferase (Tdt)-mediated nick end labeling assay, and annexin V staining. And mitogen-activated protein kinase activation and heat shock proteins expression were determined by immunoblot with specific antibodies. The antitumor effect of PPZ was evaluated in vivo by a xenograft model of nude mice. And, to address the relationship between H.pylori infection and angiogenesis, comparative analysis of density of CD34+ blood vessel was performed in tissues obtained from 20 H.pylori positive gastritis and 18 H.pylori negative gastritis patients. Expression of hypoxia inducible factor 1 (HIF-1α) and vascular endothelial growth factor (VEGF) was tested by reverse transcription-polymerase chain reaction and secretion of interleukin 8, and VEGF was measured by ELISA. To evaluate the direct effect of H.pylori infection on the tubular formation of human umbilical vein endothelial cells (HUVEC), an in vitro angiogenesis assay was employed. Activation of MAPK and nuclear factor κB was detected by immunoblotting. After PPZ treatment, apoptotic cell death was seen selectively in cancer cells and was accompanied with extracellular signal-regulated kinase deactivation. By contrast, normal gastric mucosal cells showed the resistance to PPZ-induced apoptosis through the overexpression of anti-apoptotic regulators including HSP70 and HSP27. In a xenograft model of nude mice, administration of PPZ significantly inhibited tumorigenesis and induced large-scale apoptosis of tumor cells. And, H.pylori positive gastritis patients showed a higher density of CD34+ blood vessels (mean 40.9(SEM 4.4)) than H.pylori negative gastritis patients (7.2±0.8), which was well correlated with expression of HIF-1α. Conditioned media from H.pylori infected gastric epithelial cells directly induced tubular formation of HUVEC and the increase of in vitro angiogenesis was suppressed by PPI treatment. Infection of H.pylori significantly upregulated expression of HIF-1α and VEGF in gastric epithelial cells and expression of proangiogenic factors was mediated by MAPK activation and partially responsible for NFκB activation. PPIs effectively inhibited the phosphorylation of MAPK ERK1/2 that is a principal signal for H.pylori induced angiogenesis. In conclusion, PPZ selectively induced in vivo and in vitro apoptotic cell death in gastric cancer, suggesting that proton pump inhibitors could be used for selectively anticancer effects. And, the fact that PPZ could downregulate H.pylori induced angiogenesis indicates that antiangiogenic treatment using a PPZ could be a promising protective therapeutic approach for H.pylori associated carcinogenesis.

Author dc:creator

• 김, 동규

Contributors dc:contributor

• 조, 성원
• 대학원 의학과
• 200624163

• 위산억제제
• 세포자사멸
• 헬리코박터 파이로리균

Language dc:language

en

Identifier

http://dcoll.ajou.ac.kr:9080/dcollection/jsp/common/DcLoOrgPer.jsp?sItemId=000000009153
000000009153

OAI identifier oai:identifier

oai:repository.ajou.ac.kr:201003/1342