Helicobacter pylori, inflammation, oxidative damage and gastric cancer: a morphological, biological and molecular pathway. Eur J Cancer Prev. 2008;17:195-200. [PMID: 18414189 DOI: 10.1097/cej.0b013e3282f0bff5]

Involvement of VDAC1 and Bcl-2 family of proteins in VacA-induced cytochrome c release and apoptosis of gastric epithelial carcinoma cells

OBJECTIVE

It is known that the vacuolating cytotoxin (VacA) could induce apoptosis. However, the mechanism remained to be elucidated. The aim of this study is to investigate the role of Bcl family of proteins (Bcl-2 and Bax) and the mitochondrial voltage-dependent anion channel (VDAC) in VacA-induced apoptosis of AGS cells.

METHODS

Plasmid pGBKT7-VacA p58 was constructed and transfected into the AGS cells. RT-PCR and Western blotting were used to determine the expressions of cytochrome c, caspase-3, Bax, Bcl-2 and VDAC1 mRNA and proteins.

RESULTS

VacA p58 can induce cytochrome c release and activate caspase-3 in AGS cells. It up-regulated the expressions of Bax and VDAC1 mRNA and proteins, and decreased the expression of Bcl-2 in AGS cells.

CONCLUSION

VacA p58 induces apoptosis in AGS cells. This apoptotic process is associated with the up-regulation of Bax/VDAC1 and downregulation of Bcl-2. These findings suggest that the release of cytochrome c by VacA p58 is mainly through VDAC-dependent and Bcl-2 family-dependent pathways.

Insulin-like growth factor-I regulates the liver microenvironment in obese mice and promotes liver metastasis

Among the mechanisms implicated in the tumor-promoting effects of obesity, signaling by insulin-like growth factor-I (IGF-I) and insulin has received considerable attention. However, the emerging realization that obesity is associated with chronic inflammation has prompted other consideration of how the IGF-I axis may participate in cancer progression. In the present study, we used two mouse models of chronic (LID) and inducible (iLID) igf-1 gene deficiency in the liver to investigate the role of IGF-I in regulating the host microenvironment and colorectal carcinoma growth and metastasis in obese mice. Obese mice had a heightened inflammatory response in the liver, which was abolished in mice with chronic IGF-I deficiency (LID). In control animals changes to the hepatic microenvironment associated with obesity sustained the presence of tumor cells in the liver and increased the incidence of hepatic metastases after intrasplenic/portal inoculation of colon carcinoma cells. These changes did not occur in LID mice with chronic IGF-1 deficiency. In contrast, these changes occurred in iLID mice with acute IGF-1 deficiency, in the same manner as the control animals, revealing a fundamental difference in the nature of the requirement for IGF-1 on tumor growth and metastasis. In the setting of obesity, our findings imply that IGF-1 is critical to activate and sustain an inflammatory response in the liver that is needed for hepatic metastasis, not only through direct, paracrine effect on tumor cell growth, but also through indirect effects involving the tumor microenvironment.

A systematic review of the anticancer properties of berberine, a natural product from Chinese herbs

Natural products represent a rich reservoir of potential small chemical molecules exhibiting antiproliferation and anticancer properties. An example is berberine, a protoberberine alkaloid widely distributed in medical plants used in traditional Chinese prescriptions. Recent advances have shown that berberine exerts anticancer activities both in vitro and in vivo through different mechanisms. Berberine shows inhibitory effects on the proliferation and reproduction of certain tumorigenic microorganisms and viruses, such as Heliobacter pylori and hepatitis B virus. Transcriptional regulation of some oncogene and carcinogenesis-related gene expression and interaction with both DNA and RNA are also well documented. Besides, berberine is a broad spectrum enzyme inhibitor, which affects N-acetyltransferase, cyclooxygenase-2, and topoisomerase activities and gene/protein expression. These actions, together with the regulation of reactive oxygen species production, mitochondrial transmembrane potential, and nuclear factor-kappaB activation might underlie its antiproliferative and proapoptotic effects. More importantly, the suppression of tumor growth and metastasis, the beneficial application in combined medication, and the improvement of multidrug resistance both in vivo and in vitro clearly show its potential as an alternative medicine for tumor chemotherapy.

Loss of RegI in conjunction with gastrin deficiency in mice facilitates efficient gastric ulcer healing but is dispensable for hyperplasia and tumourigenesis

RegI (Regenerating islet derived-1) was originally characterized as a growth factor involved in pancreatic islet cell regeneration. It is also considered a gastrointestinal mitogen as its expression is increased during pathologies involving aberrant cell proliferation that can lead to neoplasia. However, the absolute requirement for RegI to directly stimulate gastric mucosal cell proliferation in vivo requires further investigation. We used RegI-deficient mice to determine the requirement for RegI in normal gastric mucosal development, wound healing, hyperplasia and tumourigenesis. We found that epithelial repair of acetic acid ulcers in compound mutant RegI/gastrin-deficient mice was significantly reduced compared to wild type, RegI-deficient or gastrin-deficient mice. In contrast, RegI was dispensable for normal gastric mucosal development, hyperplasia in HKbeta-deficient mice and tumourigenesis in gp130(F/F) mice. Although RegI was not required for proliferation in these pathological models, expression of multiple Reg family members were increased during gp130(F/F) tumourigenesis. Interestingly, loss of RegI in gp130(F/F) mice resulted in decreased expression of other Reg family members. Our results indicate that RegI and gastrin may synergistically regulate gastric mucosal proliferation during certain pathological settings like wound healing while gastric epithelial proliferation in other pathologies may require coordinated expression of multiple Reg genes.

Nature meets nurture: molecular genetics of gastric cancer

The immensity of genes and molecules implicated in gastric carcinogenesis is overwhelming and the relevant importance of some of these molecules is too often unclear. This review serves to bring us up-to-date with the latest findings as well as to look at the larger picture in terms of how to tackle the problem of solving this multi-piece puzzle. In this review, the environmental nurturing of intestinal cancer is discussed, beginning with epidemiology (known causative factors for inducing molecular change), an update of H. pylori research, including the role of inflammation and stem cells in premalignant lesions. The role of E-cadherin in the nature (genotype) of diffuse gastric cancer is highlighted, and finally the ever growing discipline of SNP analysis (including IL1B) is discussed.

Genetic factors associated with intestinal metaplasia in a high risk Singapore-Chinese population: a cohort study

Background

Intestinal metaplasia (IM) is an important precursor lesion in the development of gastric cancer (GC). The aim of this study was to investigate genetic factors previously linked to GC risk for their possible association with IM. A total of 18 polymorphisms in 14 candidate genes were evaluated in a Singapore-Chinese population at high risk of developing GC.

Methods

Genotype frequencies were compared between individuals presenting with (n = 128) or without (n = 246) IM by both univariate and multivariate analysis.

Results

Carriers of the NQO1 609 T allele showed an association with IM in individuals who were seropositive for Helicobacter pylori (HP+; OR = 2.61, 95%CI: 1.18-5.80, P = .018). The IL-10 819 C allele was also associated with IM in HP+ individuals (OR = 2.32, 95%CI: 1.21-4.43, P = 0.011), while the PTPN11 A allele was associated with IM in HP- individuals (OR = 2.51, 95%CI: 1.16-5.40, P = 0.019), but showed an inverse association in HP+ subjects (OR = 0.46, 95%CI: 0.21-0.99, P = 0.048).

Conclusion

Polymorphisms in NQO1, IL-10 and PTPN11, in combination with HP status, could be used to identify individuals who are more likely to develop IM and therefore GC.

Diet synergistically affects helicobacter pylori-induced gastric carcinogenesis in nonhuman primates

BACKGROUND & AIMS

Gastric cancer results from a combination of Helicobacter pylori (H pylori) infection, exposure to dietary carcinogens, and predisposing genetic make-up. Because the role of these factors in gastric carcinogenesis cannot be determined readily in human beings, the present study examined the role of an oral carcinogen and H pylori infection in rhesus monkeys.

METHODS

Gastroscopies were performed in 23 monkeys assigned to 4 groups: controls; nitrosating carcinogen ethyl-nitro-nitrosoguanidine administration alone; inoculation of a virulent H pylori strain alone (H); and ethyl-nitro-nitrosoguanidine in combination with H pylori (EH). Follow-up gastroscopies and biopsies were performed at 3-month intervals for 5 years for pathologic and molecular studies.

RESULTS

Postinoculation, H and EH groups showed persistent infection and antral gastritis. Starting at 2 and 5 years, respectively, gastric intestinal metaplasia and intraepithelial neoplasia developed in 3 EH monkeys but in no other groups. Transcriptional analysis of biopsy specimens at 5 years revealed group-specific expression profiles, with striking changes in EH monkeys, plus a neoplasia-specific expression profile characterized by changes in multiple cancer-associated genes. Importantly, this neoplastic profile was evident in nonneoplastic mucosa, suggesting that the identified genes may represent markers preceding cancer.

CONCLUSIONS

Gastric intraglandular neoplasia is induced in primates when H pylori infection is associated with consumption of a carcinogen similar to the nitrosamines found in pickled vegetables, suggesting that H pylori and the carcinogen synergistically induce gastric neoplasia in primates.

Nature meets nurture: molecular genetics of gastric cancer

The immensity of genes and molecules implicated in gastric carcinogenesis is overwhelming and the relevant importance of some of these molecules is too often unclear. This review serves to bring us up-to-date with the latest findings as well as to look at the larger picture in terms of how to tackle the problem of solving this multi-piece puzzle. In this review, the environmental nurturing of intestinal cancer is discussed, beginning with epidemiology (known causative factors for inducing molecular change), an update of H. pylori research, including the role of inflammation and stem cells in premalignant lesions. The role of E-cadherin in the nature (genotype) of diffuse gastric cancer is highlighted, and finally the ever growing discipline of SNP analysis (including IL1B) is discussed.

Genetic variation in immune regulation and DNA repair pathways and stomach cancer in China

The incidence of stomach cancer is high in certain parts of the world, particularly in China. Chronic Helicobacter pylori infection is the main risk factor, yet the vast majority of infected individuals remain unaffected with cancer, suggesting an important role of other risk factors. We conducted a population-based case-control study including 196 incident stomach cancer cases and 397 matched controls to test the hypothesis that adverse single nucleotide polymorphism (SNP) genotypes and haplotypes within genes of the DNA repair and immune regulatory pathways are associated with increased stomach cancer risk. Genomic DNA isolated from blood samples was used for genotyping, and results were obtained for 57 putatively functional SNPs in 28 genes. Odds ratios (OR) and 95% confidence intervals (95% CI) were obtained from adjusted logistic regression models. For PTGS2, a gene involved in the inflammatory response, associations with stomach cancer risk were observed for TC genotype carriers of rs5279 (OR, 0.24; 95% CI, 0.08-0.73), CT genotype carriers of the 3'-untranslated region SNP rs689470 (OR, 7.49; 95% CI, 1.21-46.20), and CTTC haplotype carriers of rs5277, rs5278, rs5279, and rs689470 (OR, 0.41; 95% CI, 0.18-0.95). For ERCC5, a gene involved in nucleotide excision repair, TC genotype carriers of rs1047768 (OR, 0.65; 95% CI, 0.41-1.03), GC genotype carriers of the nonsynonymous SNP rs2227869 (OR, 0.30; 95% CI, 0.13-0.67), and CCG haplotype carriers of rs1047768, rs17655, and rs2227869 (OR, 0.45; 95% CI, 0.20-1.04) were associated with reduced stomach cancer risk. In conclusion, PTGS2 and ERCC5 were associated with stomach cancer risk in a Chinese population.

Effect of Helicobacter pylori eradication on incidence of gastric cancer in human and animal models: underlying biochemical and molecular events

BACKGROUND

Gastric cancer remains one of the most common cancers worldwide. A strong association exists between Helicobacter pylori infection and the risk of developing noncardia gastric cancer. H. pylori eradication by antibiotic treatment is regarded as a primary chemoprevention strategy to reduce gastric cancer incidence.

AIM

To analyze the efficacy of H. pylori eradication in preventing gastric cancer in human and animal models, and to discuss whether biochemical, genetic, and epigenetic changes associated with H. pylori infection are reversible after curing the infection.

RESULTS

Several intervention trials have indicated that in some patients, H. pylori eradication leads to regression and prevents the progression of precancerous lesions. The eradication therapy reduces gastric cancer incidence in patients without any precancerous lesions at the baseline and is most effective before the development of atrophic gastritis. A few recent intervention studies in Japan have demonstrated significant prophylactic effects of eradication therapy on the development of gastric cancer, suggesting the use of eradication therapy in high-risk populations as a gastric cancer reduction strategy. However, gastric cancer may still develop despite successful eradication therapy. Studies in animal models have confirmed the use of eradication therapy at an early point of infection to prevent gastric cancer development.

CONCLUSION

H. pylori eradication may not completely abolish the risk of gastric cancer. However, eradication therapy may be used in high-risk populations to reduce gastric cancer incidence. It can reverse many biochemical, genetic, and epigenetic changes that H. pylori infection induces in the stomach.

Inflammation and liver cancer: new molecular links

A connection between inflammation and cancer has been long suspected. Epidemiological studies have established that many tumors occur in association with chronic infectious diseases, and it is also known that persistent inflammation in the absence of infections increases the risk and accelerates the development of cancer. One clear example of inflammation-related cancer is hepatocellular carcinoma (HCC). HCC is a type tumor that slowly unfolds on a background of chronic inflammation mainly triggered by exposure to infectious agents (hepatotropic viruses) or to toxic compounds (ethanol). The molecular links that connect inflammation and cancer are not completely known, but evidences gathered over the past few years are beginning to define the precise mechanisms. In this article we review the most compelling evidences on the role of transcription factors such as NF-kappaB and STAT3, cytokines like IL-6 and IL-1alpha, ligands of the EGF receptor and other inflammatory mediators in cancer development, with special emphasis in HCC. The molecular dissection of the pathways connecting the inflammatory reaction and neoplasia will pave the way for better therapies to treat cancers.

In situ detection of Helicobacter pylori in gastric cancer and precancerous diseases and its significance

AIM: To investigate the distribution of H pylori infection in gastric cancer and precancerous diseases and the role of H pylori infection in the incidence and differentiation of gastric cancer, as well as the clinical value of H pylori infection detection using immunohistochemical method.

METHODS: Biopsy specimens of gastric mucosa in various diseases were randomly selected from 327 cases in Zhuanghe region in Liaoning Province, including 63 cases of superficial gastritis, 62 cases of atrophic gastritis and 202 cases of gastric cancer. HE staining and immunohistochemical staining were used to measure the density of H pylori infection in gastric mucosa and mucus.

RESULTS: The H pylori colonization status was higher in superficial gastritis group or in atrophic gastritis than gastric cancer group (χ² = 96.998, 87.542, both P < 0.01), while the status was lower in gastric cancer group than peri-cancer mucosa (χ² = 5.378, P < 0.01), higher in the intestinal gastric cancer group than in diffused gastric cancer (χ² = 19.253, P< 0.01). When H pylori density score was ≤ 2, the H pylori free status in superficial gastritis and atrophic gastritis were lower than that of gastric cancer (χ² = 6.526, 6.218, both P < 0.01), and when H pylori density score > 2, it was higher in superficial gastritis group or atrophic gastritis group than in gastric cancer group (χ² = 20.252, 46.248, both P < 0.01), it was higher in atrophic gastritis than in superficial gastritis (χ² = 4.746, P < 0.05), and it was higher in the intestinal gastric cancer than in diffused gastric cancer (χ² = 6.784, P < 0.01).

CONCLUSION: The H pylori distribution is higher in superficial gastritis and atrophic gastritis than in gastric cancer, lower in gastric cancer than in peri-cancer mucosa, higher in the intestinal gastric cancer than in diffused one. There is no significant difference in the free H pylori density score between gastric cancer tissue and peri-cancer mucosa. Immunohistochemical detection of H pylori is better than HE staining.