BACKGROUND: Epidemiological and animal studies demonstrated a link between gastric cancer (GC) or mucosal associated lymphoid tissue (MALT) lymphoma and chronic infection with Helicobacter pylori (H. pylori). The exact mechanism responsible for the development of GC and MALT-lymphoma in H. pylori-infected patients still remains obscure. This report is designed to overview the molecular biology, especially the gene expression and histochemical manifestation of gastrin and other growth factors such as transforming growth factor alpha (TGF alpha) and hepatocyte growth factor (HGF) in the GC before and after eradication of H. pylori. Furthermore, gene expression of cyclooxygenase-1 (COX-1) and COX-2 and apoptosis-related proteins such as Bax and Bcl-2 are discussed. MATERIAL AND METHODS: The findings originate from two series of patients; Series I involving 337 GC patients and 400 age- and gender-matched controls and series 2 including 20 MALT-lymphoma patients and 40 matched controls. RESULTS: An overall H.pylori-seropositivity reached about 80% in GC and about 90% in MALT-lymphoma, significantly higher than in non-cancer controls (60%). The prevalence of CagA-positive strains was about twice as high (about 70%) in GC and MALT-lymphomas as in sex- and age-matched controls. Expression of gastrin was detected in antrum of all tested patients but also in majority (90%) of GCs and MALT-lymphomas tumor tissue. HGF and TGF alpha were expressed more frequently in GC tissue than in normal fundic mucosa. COX-1 was similarly expressed in GC and MALT as in intact mucosa, while COX-2 mRNA was detected only in tumor tissue, being attenuated by H.pylori eradication in GC and abolished by this therapy in MALT-lymphoma. The plasma levels of alpha-amidated gastrin in GC and MALT were several folds higher than in controls. Gene expression of bcl-2 was detected in all, while bax--only in about 50% of GC samples. CONCLUSIONS: Infection with H. pylori, especially that expressing CagA-positivity, is primum movens in developing GC and MALT-lymphoma and the upregulation of growth factors, particularly of gastrin, and COX-2 and dysregulation of the Bax/Bcl-2 system seem to contribute to gastric cancerogenesis.

Antigens, Bacterial↗

PubMedDate not supplied

Molecular basis of colorectal cancer - role of gastrin and cyclooxygenase-2.

BACKGROUND: Tumors arising in the colorectal area have worldwide distribution and concern mostly older population being attributed to genetic, dietary and hormonal factors but most recently also to infection with Helicobacter pylori (HP). Both, HP discovery and molecular biology of colorectal cancer have been recently considered as two of ten greatest advances of gastroenterology at the dawn of 3rd millenium but little information is available regarding the relationship between the HP and colorectal cancer. Since HP infection is usually accompanied by an increase in plasma level of gastrin, which is also recognized as a trophic hormone for the colonic epithelium and a potent mitogen capable to induce cyclooxygenase-2 (COX-2), we decided 1) to compare the seroprevalence of HP, its cytotoxic protein, CagA, and cytokines (TNFalpha, IL-1beta and IL-8) in colorectal cancer patients, before and after removal of cancer, with those in age- and gender-matched controls; 2) to determine the gene expression of gastrin and gastrin receptors (CCK(B)-R) in colorectal cancer tissue, 3) to assess the plasma levels and tumor tissue contents of gastrin, 4) to examine the mRNA expression of cyclooxygenase COX-1 and COX-2 cancer tissue and intact colonic mucosa. MATERIAL AND METHODS: The trial material included 80 patients with colorectal cancers and 160 age- and gender-matched controls. Anti-HP IgG, anti-CagA IgG seroprevalence and cytokine levels were estimated by ELISA tests. Gene expressions of gastrin, CCK(B)-R, COX-1, COX-2 and Bax and Bcl2 was examined using RT-PCR, while gastrin was measured by RIA. RESULTS: The HP IgG seroprevalence, especially that expressing CagA, was significantly higher in colorectal cancer patients than in controls and did not change one week after tumor resection while plasma cytokines were significantly reduced after this operation. Gastrin and CCK(B)-R mRNA were detected in the cancer tissue and the resection margin and similarly COX-2 mRNA was expressed in most of cancers and their resection margin but not in intact colonic mucosa where only COX-1 was detected. The colorectal cancer tissue contained several folds more immunoreactive gastrin than cancer resection margin and many folds more than the intact colonic mucosa. CONCLUSIONS: 1) Colorectal carcinoma and its resection margin overexpress gastrin and receptors for gastrin (CCK(B)-R), and COX-2; 2) here, we propose that an increased plasma level of gastrin should be considered as suitable biomarker of colorectal cancer, 3) HP infection may contribute to colonic cancerogenesis by enhancing expression of gastrin and COX-2, they may account for stimulation of the tumor growth, angiogenesis and reduction in apoptosis as evidenced an increased ratio of mRNA expression for anti-apoptotic Bcl2 over proapoptotic Bax proteins and 4) HP positive patients who develop colorectal cancer should be subjected to the HP eradication; this is expected to reduce hypergastrinemia and to attenuate COX-2 expression. Our final conclusion would be: treatment of patients with colorectal cancer with COX-2 selective inhibitors now gained a strong support as a preventive measure.

Aged↗

PubMedDate not supplied

Gastric MALT-lymphoma, gastrin and cyclooxygenases.

Malt-lymphoma, gastrin and COX-2 interaction. Low grade, mucosal associated lymphoid tissue (MALT)-lymphoma is an unique among gastric malignancies where causal involvement of Helicobacter pylori (H. pylori) infection has been proposed based on complete regression of the tumor following the eradication therapy. In this report ten primary, low-grade MALT-lymphomas have been examined before and 6 months after one week of successful eradication therapy (clarithromycin + amoxicillin + omeprazole). Gastric biopsy samples from tumor and intact antrum and corpus mucosa were obtained during endoscopy before and after eradication for assessment of expression of gastrin and gastrin receptor (CCKB-R) as well as cyclooxygenase (COX)-1 and COX-2 using RT-PCR. The gastric lumen and serum gastrin and mucosal and tumor tissue PGE2 biosynthesis were determined by RIA before and after H. pylori eradication. Eradication of H. pylori resulted in complete endoscopic and histological remission of MALT-lymphoma in 9 out of 10 patients as assessed 6 months after this eradication. Before eradication, the mRNA expression for gastrin and CCKB-R as well as mRNA expression for COX-1 and COX-2 were observed in tumor tissue and infected mucosa, while corpus mucosa expressed only CCKB-R and antrum mucosa only gastrin. Six months upon the eradication when MALT-lymphoma completely regressed both endoscopically and histologically in 9 of 10 tested subjects, the expression of gastrin and COX-2 disappeared from the former area of MALT-lymphoma tumor. Gastrin mRNA remained detectable only in antrum mucosa, CCKB-R mRNA in corpus mucosa and COX-1 mRNA both in antrum and corpus mucosa. Gastric luminal and serum gastrin levels and gastric mucosa and tumor PGE2, which were greatly elevated before eradication, became normalized after this procedure. This study demonstrates that low-grade MALT-lymphoma is linked to H. pylori infection which may promote the expression and excessive release of gastrin and COX-2 expression that could be involved in the pathogenesis of MALT-lymphoma.

Amoxicillin↗

PubMedDate not supplied