Artur Hartwich

Helicobacter pylori infection and gastrin and cyclooxygenase expression in gastric and colorectal malignancies

Helicobacter pylori, infecting more than 50% of the world population, results in gastritis, usually located in the antral portion of the stomach, accompanied by hypergastrinemia, the key factor in gastric and colorectal carcinogenesis. Excessive mucosal cell proliferation for many years may eventually result in gastric atrophy, cell mutation and transformation of gastric mucosal cells into gastrin-producing cells, which also express gastrin receptors serving to stimulate cell proliferation and tumor growth. These processes may be completed by the expression of cyclooxygenase-2 (COX-2) as an inflammation enzyme to release excessive amounts of PGE(2), leading to further proliferation, reduction in apoptosis, angiogenesis and tumor growth. H. pylori eradication results in complete regression of MALT lymphoma and subsequent normalisation of excessive gastrin release and COX-2 expression. Reduction of gastrin by active immunisation (gastrimmune), blocking of gastrin receptors with specific blockers and suppression of COX-2 might be helpful in inhibiting tumor growth and invasion.

Helicobacter pylori and CagA status, serum gastrin, interleukin-8 and gastric acid secretion in gastric cancer.

Background: Despite numerous epidemiological studies, the association between Helicobacter pylori infection and gastric cancer (GC) remains unexplained. This study was designed to determine the seropositivity of H. pylori and cytotoxin-associated gene A (CagA), serum gastrin and interleukin-8 (IL-8) levels as well as basal intragastric pH and maximal histamine-induced gastric acid outputs (MAO) in a large series of GC patients and controls. Methods: 337 GC patients (118 men and 219 women; median age 59.4; range 21-87) and 337 controls randomized for sex and age entered the study. Serum IgG antibodies to H. pylori and CagA and serum levels of IL-8 were measured by enzyme-linked immunosorbent assay, while serum-amidated gastrin was determined by specific radioimmunoassay and correlated with gastric luminal pH. Results: The numbers of GC patients and controls involved in the study in various age groups, ranging from 20 to >70 years, were similar, but overall H. pylori IgG seropositivity in GC patients was significantly higher (90.8%) than in controls (79.2%). The overall CagA seropositivity in GC patients was about double (58.2%) that in controls (25.2%). Serum gastrin levels over the calculated cut-off value (38.88 pM/L) were found in several-fold larger number in GC patients (48%) than in controls (8.3%) and, similarly, serum IL-8 values over the cut-off point (1.77 pg/mL) occurred in almost all (99.7%) GC patients but in only a few controls (0.3%). Basal intragastric pH above the cut-off point (pH = 4.50) was observed in about 58.2% of GC patients compared to 15.1% in controls, and strong correlation between the serum gastrin and gastric pH was found in GC but weak in controls. The cut-off value for MAO was 12.3 mml/h; MAO below this cut-off value occurred in 89.9% of GC patients and in only 4.7% of controls. A summary odds ratio (SOR) in GC for H. pylori IgG was 2.59 (95% Cl; 1.61-4.22) for CagA - 4.12 (95% Cl; 2.93-5.8), for serum gastrin - 10.25 (95%; 6.47-16.47) and for MAO - 15.2 (95% Cl; 9.45-39.82). Multivariable analysis of serum gastrin, IgG and CagA, and luminal pH and MAO values revealed that only gastrin and CagA have significant influence on GC formation (OR >1 in logistic regression). Conclusions: 1. CG patients show significantly higher H. pylori IgG and CagA seropositivity than dyspeptic age- and gender-matched controls, confirming that gastric infection with CagA expressing H. pylori greatly increases the risk of GC. 2. Serum gastrin levels in GC but not in controls are correlated with the rise in intragastric pH, indicating that excessive gastrin release in GC is affected by lower intragastric pH. 3. Serum gastrin level and CagA seropositivity are significantly increased in the majority of GC patients, and are the only variables in multivariable analysis to have a predominant influence on GC formation, which suggests that both these parameters may be implicated in H. pylori -related gastric carcinogenesis. 4. H. pylori -infected GC patients produce significantly more IL-8 than do non-GC controls, probably reflecting CagA-positive H. pylori -associated gastritis.

Influence of COX-2 Inhibition by Rofecoxib on Serum and Tumor Progastrin and Gastrin Levels and Expression of PPARγ and Apoptosis-Related Proteins in Gastric Cancer Patients

Cyclooxygenase-2 (COX-2) expression and certain growth hormones, such as gastrin, have been related to gastric carcinogenesis, but little is known about the factors that enhance this COX-2 expression and whether specific blockade of this enzyme has any influence on tumor growth and progression. Our objective was to determine the influence of a specific COX-2 inhibitor, rofecoxib (Vioxx), on serum and tumor levels of gastrin and its precursor, progastrin, as well as on tumor gene expression of COX-2, peroxisome proliferator-activated receptor gamma (PPARγ), and apoptosis-related proteins (Bax and Bcl-2, caspase-3, and survivin). Twenty-four gastric cancer (GC) patients entered this study and were examined twice, once before and then following a 14-day treatment with Vioxx at a dose of 25 mg twice daily. For comparison, 48 age- and sex-matched healthy controls and 24 similarly matched Helicobacter pylori (Hp)-positive subjects were enrolled and treated with Vioxx as GC patients. Serum levels of anti-Hp and anti-CagA antibodies as well as IL-8 and TNF-α were measured by enzyme-linked immunosorbent assay (ELISA), while serum and tumor contents of progastrin and amidated gastrin were determined by specific RIA. Tumor gene and protein expressions of COX-2, PPARγ, Bax and Bcl-2, caspase-3, and survivin were determined by RT-PCR and western blot. The overall Hp and CagA seropositivity in 24 GC patients was significantly higher (82% and 47%) than in 48 controls (61% and 22%) but not in 24 Hp-infected subjects (100% and 38%). Serum IL-8 and TNF-α values were significantly higher in GC patients than in controls without GC or Hp-infected controls. Median serum progastrin and gastrin levels were found to be significantly higher in GC than in controls without GC and in Hp-positive subjects. Treatment of GC patients with Vioxx resulted in a significant decrease in plasma and tumor contents of both progastrin and gastrin, and this was accompanied by the increment in tumor expression of COX-2, PPARγ, Bax, and caspase-3 with a concomitant reduction in Bcl-2 and survivin expression. We conclude that: (1) GC patients show significantly higher Hp and CagA seropositivity than age- and sex-matched controls, but not Hp-positive subjects, indicating that infection with cytotoxic Hp is linked to GC. (2) Serum progastrin and gastrin levels are signficantly higher in GC patients than in matched controls, confirming that both gastrins may be implicated in gastric carcinogenesis. (3) GC patients exhibit significantly higher levels of IL-8 and TNF-α than non-GC controls and Hp-positive subjects, probably reflecting more widespread gastritis in GC. (4) COX-2, PPARγ, Bcl-2, and survivin were overexpressed in gastric tumor, but the inhibition of COX-2 activity by Vioxx resulted in a significant reduction in serum and tumor levels of progastrin and gastrin and serum IL-8 and TNF-α levels, suggesting that gastrin and proinflammatory cytokines could mediate the up-regulation of COX-2 in gastric cancerogenesis. (5) Vioxx also enhanced expression of COX-2, PPARγ, Bax, and caspase-3, while inhibiting the expression of Bcl-2 and survivin, suggesting that COX-2 blockade might be useful in chemoprevention against cancer possibly due to enhancement of the PPAR-γ and proapoptotic proteins-dependent apoptosis and the reduction in progastrin/gastrin-induced promotion of tumor growth.

Progastrin and Cyclooxygenase-2 in Colorectal Cancer

Colorectal cancers (CRCs) are one of the most common forms of cancer in Poland and one of the leading causes of death. The tumors have been attributed to genetic, dietary, and other environmental factors, but recently growth factors such as gastrin have also been implicated in the carcinogenesis. The relationship between plasma amidated and nonamidated gastrin in CRCs is controversial. This study was designed (1) to determine the plasma levels of progastrin and amidated gastrin in 50 CRC patients before and 3–6 months after removal of the tumor, (2) to determine the tumor concentrations of these gastrin peptides and the level of expression for gastrin mRNA and gastrin/CCKB receptor mRNA, (3) to examine the expression of cyclooxygenase COX-1 and COX-2 mRNA in CRC tissue, and (4) to compare the prevalence of Hp and its cytotoxic protein, CagA, and cytokines (TNFα, IL-1β, and IL-8) in CRCs, before and after removal of tumor. It was found that the CRC, its resection margin, and the plasma contained severalfold higher levels of progastrin than of amidated gastrins and that the removal of the CRC tumor resulted in a marked reduction in plasma progastrin level without a significant alteration in plasma levels of amidated gastrins. Both gastrin and CCKB-R mRNA were detected in the cancer tissue and resection margin by RT-PCR, and similarly, COX-1 and COX-2 mRNA were expressed in these tissues of most CRCs. The seroprevalence of Hp, especially that expressing CagA, and levels of IL-1β, but not other cytokines, were significantly higher in CRC patients than in 100 age-, gender-, and profession-matched controls and did not change significantly about 3–6 months after tumor resection. We conclude that (1) the CRC and its margin contain large amounts of progastrin and show gene expression of gastrin, CCKB-R, and COX-2; (2) removal of the CRC markedly reduces the plasma concentrations of progastrin; (3) the Hp infection rate is higher in CRC, and this may contribute to colorectal cancerogenesis via enhancement of progastrin and gastrin release; and (4) plasma progastrin concentrations might serve as a biomarker of CRC.

Serum progastrin and its products, gastric acid secretion and serum pepsinogen I in gastric cancer.

Background: Numerous studies have shown an association between Helicobacter pylori (Hp) infection and gastric cancer (GC). Study: This study was designed to determine the role of cytotoxin-associated gene A (CagA)-positive Hp infection, serum amidated gastrins and their precursor, progastrin, gastric acidity and serum pepsinogen I (PG-I) levels in gastric cancerogenesis in 74 cancer patients and in 77 age- and gender-matched controls. Serum IgG antibodies to Hp and CagA and levels of IL-8 and PG-I were measured by ELISA, while progastrin and amidated gastrin by specific radioimmunoassay. Results: The overall Hp and CagA seropositivity in GC patients were significantly higher (82 and 60%) than in matched controls (61 and 27%, respectively). Progastrin and amidated gastrin levels over their cutoff points (122 and 32 pM, respectively) were found in a significantly larger number of GC (59.4 and 44.5%) than in controls (9.0 and 16.8%, respectively). Histologically, all these GCs with increased serum progastrin and amidated gastrins were of intestinal type and showed CagA and Hp seropositivity. Serum IL-8 and gastric pH, above their cutoff points (pH >4.5), and serum PG-I level below its cutoff point (44.2 µg/l) were observed in a significantly higher number of GC patients as compared to controls. Conclusions: (1) GC patients have higher Hp and CagA seroprevalence than matched controls, confirming that CagA-positive Hp infection is associated with higher risk of GC; (2) serum levels of amidated gastrins and their precursor, progastrin, as well as IL-8 are significantly higher, while serum PG-I levels are reduced in intestinal type GC compared to controls, and (3) determination of high serum progastrin, amidated gastrins and IL-8 combined with low serum PG-I may be useful biomarkers of GC.