The relationship between Helicobacter pylori infection and the effects of chemotherapy in patients with advanced or metastatic gastric cancer. Cancer Chemother Pharmacol. 2012;70:555-558. [PMID: 22871922 DOI: 10.1007/s00280-012-1944-5]

MicroRNAs in Helicobacter pylori-infected gastric cancer: Function and clinical application

Gastric cancer (GC) is the leading cause of cancer-related death worldwide, and it is associated with a combination of genetic, environmental, and microbial risk factors. Helicobacter pylori (H. pylori) is classified as a type I carcinogen, however, the exact regulatory mechanisms underlying H. pylori-induced GC are incompletely defined. MicroRNAs (miRNAs), one of small non-coding RNAs, negatively regulate gene expression through binding to their target genes. Dysregulation of miRNAs is crucial in human cancer. A noteworthy quantity of aberrant miRNAs induced by H. pylori through complex regulatory networks have been identified. These miRNAs substantially affect genetic instability, cell proliferation, apoptosis, invasion, metastasis, autophagy, chemoresistance, and the tumor microenvironment, leading to GC development and progression. Importantly, some H. pylori-associated miRNAs hold promise as therapeutic tools and biomarkers for GC prevention, diagnosis, and prognosis. Nonetheless, clinical application of miRNAs remains in its infancy with multiple issues, including sensitivity and specificity, stability, reliable delivery systems, and off-target effects. Additional research on the specific molecular mechanisms and more clinical data are still required. This review investigated the biogenesis, regulatory mechanisms, and functions of miRNAs in H. pylori-induced GC, offering novel insights into the potential clinical applications of miRNA-based therapeutics and biomarkers.

Potential Gastric Cancer Immunotherapy: Stimulating the Immune System with Helicobacter pylori pIRES2-DsRed-Express-ureF DNA Vaccines

Most gastric cancers (GC) are thought to be caused by Helicobacter pylori (H. pylori) infections. However, there is mounting evidence that GC patients with positive H. pylori status have improved prognoses. The H. pylori-induced cellular immune reaction may inhibit cancer. In this study, BALB/c mice were immunized using recombinant plasmids that encode the ureF gene of H. pylori. Purified functional splenic CD3+ T lymphocytes are used to study the anticancer effects in vitro and in vivo. The immunological state of GC patients with ongoing H. pylori infection is mimicked by the H. pylori DNA vaccines, which cause a change in the reaction from Th1 to Th2. Human GC cells grow more slowly when stimulated CD3+ T lymphocytes are used as adoptive infusions because they reduce GC xenograft development in vivo. The more excellent ratios of infiltrating CD8+/CD4+ T cells, the decreased invasion of regulatory FOXP3+ Treg lymphocytes, and the increased apoptosis brought on by Caspase9/Caspase-3 overexpression and Survivin downregulation may all contribute to the consequences. Our findings suggest that in people with advanced GC, H. pylori pIRES2-DsRed-Express-ureF DNA vaccines may have immunotherapeutic utility.

Factors affecting survival in operated gastric cancer

In this study, our aim was to determine the possible effects of Helicobacter pylori(HP), chronic atrophic gastritis (CAG), and gastrointestinal metaplasia (GIM) on survival in operated bowel type gastric cancer patients (INT-GC). Among 548 patients, 347(63.3%) were male. The median age was 57 years. Disease-free survival (DFS) and overall survival (OS) were significantly shorter in patients with GIM than those in patients without GIM (log rank, P = 0.003 and log rank P = 0.003, respectively). Multivariate analysis showed that presence of GIM (HR, 2.1) was found to be an independent factor of worse DFS. In our study, stage pIII patients with GIM had significantly shorter DFS and OS than those without GIM (log rank p = 0.008 and log rank p = 0.001, respectively). However, in subgroup analysis of patients with GIM, there was no significant DFS and OS difference between patients with stage pI and pII disease (log rank p = 0.999, log rank p = 0.184 vs. log rank p = 0.409, log rank p = 0.281, respectively).

Anti-Helicobacter pylori antibody status is associated with cancer mortality: A longitudinal analysis from the Japanese DAIKO prospective cohort study

Paradoxically, patients with advanced stomach cancer who are Helicobacter pylori-positive (HP+) have a higher survival rate than those who are HP-. This finding suggests that HP infection has beneficial effects for cancer treatment. The present study examines whether HP+ individuals have a lower likelihood of death from cancer than those who are HP-. Prospective cohort data (n = 4,982 subjects enrolled in the DAIKO study between 2008-2010) were used to assess whether anti-HP antibody status was associated with cancer incidence. The median age in the primary registry was 53 years-old (range 35-69 years-old). Over the 8-year observation period there were 234 (4.7%) cancer cases in the cohort and 88 (1.8%) all-cause deaths. Urine anti-HP antibody data was available for all but one participant (n = 4,981; 99.98%). The number of HP+ and HP- individuals was 1,825 (37%) and 3,156 (63%), respectively. Anti-HP antibody distribution per birth year revealed that earlier birth year was associated with higher HP+ rates. With a birth year-matched cohort (n = 3,376), all-cancer incidence was significantly higher in HP+ individuals than those who were HP- (p = 0.00328), whereas there was no significant difference in the cancer death rate between HP+ and HP- individuals (p = 0.888). Cox regression analysis for prognostic factors revealed that the hazards ratio of HP+ was 1.59-fold (95%CI 1.17-2.26) higher than HP- in all-cancer incidence. Potential systemic effects of HP+ status may contribute to reduced likelihood of death for patients after an initial diagnosis of cancer.

Positive H. pylori status predicts better prognosis of non-cardiac gastric cancer patients: results from cohort study and meta-analysis

BACKGROUND

Previous researches have associated Helicobacter pylori (H. pylori) with a prognosis of gastric cancer (GC), however, without a concert conclusion. This study aimed to study this issue further by a prospective cohort study and a meta-analysis.

METHODS

Histologically diagnosed gastric cancer (GC) patients were recruited into the primary prospective cohort study between January 2009 to December 2013. All the patients were followed-up periodically to record information on post-surgery therapy and overall survival status. The pre-surgery status of H. pylori was measured by enzyme-linked immunosorbent assay. A meta-analysis was conducted after retrieving related researches in the databases of PubMed and Embase up to April 2020. Pooled hazard ratios (HRs) and 95% confidence intervals (CIs) were summarized to validate the relationship between H. pylori infection and the survival time of GC patients. I² statistics and Q test were used to assess the heterogeneity. Sensitivity analyses were performed using Galbraith's plot, leave-one-out analysis, subgroup analyses and meta-regression to explore the sources of heterogeneity and the stability of the summary results.

RESULTS

A total of 743 GC patients with radical tumorectomy were included prospectively and 516 (69.4%) were positive on H. pylori. H. pylori-positive patients tended to survive longer than -negative ones (HR 0.92, 95%CI: 0.74-1.15), though the tendency was not statistically significant. Cohort studies on the prognosis of GC were retrieved comprehensively by assessing the full-text and 59 published studies, together with the result of our study, were included in the further meta-analysis. The summarized results related the positive status of H. pylori to better overall survival (HR 0.81, 95%CI: 0.72-0.90) and disease-free survival (HR 0.83, 95%CI: 0.67-0.99). Results from subgroup analyses indicated that the pooled magnitude of this association was relatively lower in studies not referring to H. pylori in title and abstract.

CONCLUSIONS

In conclusion, gastric cancer patients with H. pylori have a better prognosis than patients of H. pylori negative. More stringent surveillance strategies may be necessary for patients with H. pylori negative at cancer diagnosis.

The prognostic role of Helicobacter pylori in gastric cancer patients: A meta-analysis

BACKGROUND

The prognostic value of Helicobacter pylori (H. pylori) infection in gastric cancer patients has been investigated over many years; however, the results remain inconclusive. Thus, we performed a comprehensive review of currently available evidence via a systemic meta-analysis to evaluate the effects of H. pylori infection on the prognosis of gastric cancer patients.

METHODS

Studies that evaluated the prognostic value of H. pylori infection in gastric cancer were extracted in March 2016 by searching PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials. We obtained or calculated hazard ratios (HRs) and the associated 95% confidence intervals (CIs) from the identified studies, and conducted random-effects model analyses of overall survival and progression-free survival. Twenty-four studies with a cumulative sample size of 7191 patients were included in our analysis.

RESULTS

Our meta-analysis revealed that H. pylori infection is an indicator of improved overall survival in gastric cancer patients (HR, 0.79; 95% CI, 0.64-0.99); however, this was only true for European patients. The benefits of H. pylori infection were not detected in Asian gastric cancer patients (HR, 1.01; 95% CI, 0.91-1.12) or those in the United States (HR, 0.88; 95% CI, 0.73-1.05). Subgroup analyses revealed that the prognostic significance of H. pylori infection differed with respect to the year of study publication, number of patients, H. pylori detection method, tumor stage, H. pylori-positive rate, and risk of bias. The prognostic value of H. pylori infection on progression-free survival was unclear (HR, 0.84; 95% CI, 0.70-1.01).

CONCLUSIONS

These data provide limited, moderate-quality evidence that H. pylori infection is an indicator of good prognosis in European gastric cancer patients. However, this is not necessarily true for other populations.

Activation of CD3+ T cells by Helicobacter pylori DNA vaccines in potential immunotherapy of gastric carcinoma

Most of gastric carcinoma (GC) is attributed to infection by Helicobacter pylori (H. pylori) but there is increasing evidence that the positive H. pylori status correlates with better prognosis in GC. The H. pylori-induced cellular immune response may suppress cancer and in this work, recombinant pcDNA3 plasmids encoding various fragments of H. pylori virulence genes of cagA, vacA and babA are constructed and combined into groups to immunize BALB/c mice. The activated splenic CD3⁺ T cells are purified and the anticancer effects are investigated in vitro and in vivo. The H. pylori DNA vaccines induce a shift in the response from Th1 to Th2 that mimicks the immune status in patients of GC with chronic H. pylori infection. The stimulated CD3⁺ T cells inhibit the growth of human GC cells in vitro and adoptive transfusions of the CD3⁺ T cells suppress the growth of GC xenograft in vivo. The effects may be caused by the larger ratios of infiltrated CD8⁺/CD4⁺ T cells, reduced infiltration of regulatory FOXP3⁺ T cells, and enhanced apoptosis induced by upregulation of Caspase-9/Caspase-3 and downregulation of Survivin. Our results reveal the potential immunotherapeutic value of H. pylori vaccine-activated CD3⁺ T cells in those with advanced GC.

Helicobacter pylori infection is associated with favorable outcome in advanced gastric cancer patients treated with S-1 adjuvant chemotherapy

BACKGROUND AND OBJECTIVES

Limited information exists regarding beneficial effects of Helicobacter pylori. To examine the effect in advanced gastric cancer, we compared survival for patients treated with surgery-only or adjuvant chemotherapy on the basis of H. pylori infection status.

METHODS

A cohort of 491 patients who underwent R0 resection for locally advanced gastric cancer between 2000 and 2009 at 12 institutions in northern Japan was included. H. pylori infection status, was assessed from paraffin-embedded formalin-fixed samples. Overall survival (OS) and disease-free survival (DFS) in surgery-only (Surgery) and adjuvant chemotherapy (S-1) groups were analyzed. A propensity score matching was employed to correct for confounding factors by indication.

RESULTS

H. pylori infection was positive in 175 patients and negative in 316 patients. H. pylori-positive patients showed significantly better survival than H. pylori-negative patients in both OS (hazard ratio [HR] 0.593, 95% confidence interval [CI] 0.417-0.843; P = 0.003]) and DFS (HR 0.679, 95%CI 0.492-0.937; P = 0.018). Propensity score matching further confirmed that S-1 was virtually only effective when tumors were H. pylori-positive.

CONCLUSIONS

The favorable outcome of H. pylori-positive patients implies that the host immune system is modulated by H. pylori enhancing the chemotherapeutic efficacy.

Identifying heterogeneous subtypes of gastric cancer and subtype‑specific subpaths of microRNA‑target pathways

The present study aimed to classify gastric cancer (GC) into subtypes and to screen the subtype-specific genes, their targeted microRNAs (miRNAs) and enriched pathways to explore the putative mechanism of each GC subtypes. The GSE13861 data set was downloaded from the Gene Expression Omnibus and used to screen differential expression genes (DEGs) in GC samples based on the detection of imbalanced differential signal algorithm. The specific genes in each subtype were identified with the cut-off criterion of U>0.04, pathway enrichment analysis was performed and the subtype-specific subpaths of miRNA-target pathway were determined. A total of 1,263 DEGs were identified in the primary gastric adenocarcinoma (PGD) samples, which were subsequently divided into four subtypes, according to the hierarchy cluster analysis. Identification of the subpaths of each subtype indicated that the subpath related to subtype 1 was miRNA (miR)-202/calcium voltage-gated channel subunit α1 (CACNA1E)/type II diabetes mellitus. The nuclear factor-κB signaling pathway was the most significantly specific pathway and subpath identified for subtype 2, which was regulated by miR-338-targeted suppression of C-C motif chemokine ligand 21 (CCL21). For subtype 3, significant related pathways included ubiquitin-mediated proteolysis and proteasome, and the important subpath was miR-146B/proteasome 26S subunit, non-ATPase 3 (PSMD3)/proteasome; focal adhesion was the significant pathway indicated for subtype 4, and the subpaths were miR-34A/vinculin (VCL)/focal adhesion and miR-34C/VCL/focal adhesion. In addition, Helicobacter pylori infection was higher in GC subtype 1 than in other subtypes. Specific genes, such as CACNA1E, CCL21, PSMD3 and VCL, may be used as potential feature genes to identify different subtypes of GC, and their associated subpaths may partially explain the pathogenetic mechanism of each GC subtype.

Positive Helicobacter pylori status is associated with better overall survival for gastric cancer patients: evidence from case-cohort studies

Helicobacter pylori (H. pylori) infection increases the gastric cancer risk; however, the influences of H. pylori infection status on the outcomes for gastric cancer patients have not yet clearly defined. Herein, we systematically assessed the epidemiological studies regarding the associations between the H.pylori infection status at diagnosis and the prognosis for gastric cancer patients with the meta-analysis methods. Thirty-three eligibility studies with 8,199 participants that had determined the H.pylori infection status and the outcomes for gastric cancer patients were identified through searching the PubMed and MEDLINE databases updated to March 1^st, 2017. The random-effects model suggested that positive H. pylori infection was associated with better overall survival with the pooled hazard ratio (HR) was 0.79 [95% confidence interval (CI) = 0.66-0.93; Q = 134.86, df = 32, P-heterogeneity < 0.001; I² = 76.3%] compared to negative patients. The association was found to be more prominent in studies with higher quality, longer following-up time and more sensitive detection methods. An inverse but not statistically significant association between the H.pylori status and the disease-free survival of the patients (pooled HR = 0.84, 95% CI = 0.61-1.05;Q = 30.48, df = 11, P-heterogeneity = 0.001; I² = 63.9%) was found, while no significant association was noticed in any subgroup analyses. These results suggested that gastric cancer patients with positive H.pylori infection status at diagnosis have better overall survival compared to negative; however, more studies are warranted to confirm the results and elucidate the underlying mechanisms.

Distinct Clinicopathological Features and Prognosis of Helicobacter pylori Negative Gastric Cancer

Background

Whether the characteristics and prognosis of gastric cancer (GC) are different in patients with and without Helicobacter pylori (HP) remains controversial. The definitions of HP status in patients with atrophic gastritis but negative tests for HP are heterogeneous. We aimed to assess the impact of HP on the prognosis of GC using different definitions.

Methods

From 1998 Nov to 2011 Jul, five hundred and sixty-seven consecutive patients with GC were included. HP status was determined by serology and histology. Patients with any positive test were defined as HP infection. Patients without HP infection whose serum pepsinogen (PG) I <70 ng/dl and PG I/II ratio < 3.0 were defined as atrophic gastritis and they were categorized into model 1: HP positive; model 2: HP negative; and model 3: exclusion of these patients.

Results

We found four characteristics of HP negative GC in comparison to HP positive GC: (1) higher proportion of the proximal tumor location (24.0%, P = 0.004), (2) more diffuse histologic type (56.1%, p = 0.008), (3) younger disease onset (58.02 years, p = 0.008) and (4) more stage IV disease (40.6%, p = 0.03). Patients with negative HP had worse overall survival (24.0% vs. 35.8%, p = 0.035). In Cox regression models, the negative HP status is an independent poor prognostic factor (HR: 1.34, CI:1.04–1.71, p = 0.019) in model 1, especially in stage I, II and III patients (HR: 1.62; CI:1.05–2.51,p = 0.026).

Conclusion

We found the distinct characteristics of HP negative GC. The prognosis of HP negative GC was poor.

The Effect of Helicobacter pylori on Gastric Cancer Treated with Adjuvant Chemotherapy After Curative Resection

Helicobacter pylori has been associated with diverse pathologies of varying severity. We investigated the H. pylori infection status and its association with the pathologic features and clinical outcomes in stage III gastric cancer patients treated with adjuvant therapy after curative resection. Between 2004 and 2009, the records of 76 consecutive patients were retrospectively reviewed. H. pylori infection was confirmed by examination of pathological specimen. The relationship between H. pylori and the clinicopathological features was analyzed by Fisher exact test, Student's t test, and Kaplan-Meier method. Of the 76 patients, 16 patients (21.1 %) were confirmed for H. pylori infection. The median age was 59 years. Twenty-three patients received chemotherapy and remainder received chemoradiotherapy. H. pylori status did not correlate with the clinicopathologic features. It was greater in non-neoplastic tissue than the tumor tissue (21.1 vs 7.9 %). Median follow-up was 21 months. During this period, 88.2 % patients had experienced tumor recurrence, and 85.5 % patients had died. Recurrence was observed in 87.5 % patients and in 88.3 % patients in H. pylori-positive and H. pylori-negative patients, respectively (P = 0.92). Disease-free survival was 28.4 ± 7.9 months and overall survival was 31.5 ± 7.4 months in H. pylori-positive patients compared with 28.3 ± 3.7 and 33.2 ± 3.4 months, respectively, in H. pylori-negative patients. H. pylori infection status did not have effect on the overall or disease-free survival (p = 0.85 and P = 0.86), respectively. H. pylori status might not be useful as a prognostic and predictive factor for clinical outcomes.

Helicobacter pylori infection, gastrin and cyclooxygenase-2 in gastric carcinogenesis

Gastric cancer is one of the most frequent neoplasms and a main cause of death worldwide, especially in China and Japan. Numerous epidemiological, animal and experimental studies support a positive association between chronic Helicobacter pylori (H. pylori) infection and the development of gastric cancer. However, the exact mechanism whereby H. pylori causes gastric carcinogenesis remains unclear. It has been demonstrated that expression of cyclooxygenase-2 (COX-2) is elevated in gastric carcinomas and in their precursor lesions. In this review, we present the latest clinical and experimental evidence showing the role of gastrin and COX-2 in H. pylori-infected patients and their possible association with gastric cancer risk.

Helicobacter pylori modulates cisplatin sensitivity in gastric cancer by down-regulating miR-141 expression

BACKGROUND

Recent studies found that gastric cancer patients with Helicobacter pylori infection had a better response to chemotherapy and had an improved overall prognosis compared with those without. However, the underlying mechanism remains unknown.

METHODS

Quantitative real-time PCR (qRT-PCR) was utilized to determine the expression profile of miR-141 in H. pylori infected cells and tissues and their respective controls. qRT-PCR and Western blot were used to determine the expression level of KEAP-1. Luciferase reporter assays were used to determine whether KEAP-1 was a direct target of miR-141 in the gastric cancer cells. MTT and apoptosis assay were performed to detect the survival of cells under cisplatin treatment.

RESULT

We found that H. pylori infection can significantly down-regulate miR-141 expression. Knockdown miR-141 expression in 7901/DDP and 7901 cells could significantly improve cisplatin sensitivity. Over-expression of miR-141 resulted in enhanced resistance to cisplatin in both gastric cancer cells. We also demonstrated that miR-141 directly targets KEAP1 by luciferase reporter assay, and that down-regulation of KEAP1 induces cisplatin resistance. Conversely, over-expression of KEAP1 significantly enhanced cisplatin sensitivity. Our 75 pairs of tissues also showed that KEAP1 was significantly up-regulated in H. pylori-positive tissues.

CONCLUSION

Altogether, these findings demonstrated that the H. pylori infection could modulate cisplatin sensitivity through miR-141-mediated regulation of KEAP1.

A genetic polymorphism in TOX3 is associated with survival of gastric cancer in a Chinese population

Purpose

Recently, genetic polymorphism (rs3803662C>T) in TOX3 was reported to induce the risk of breast cancer. In this study, we hypothesized that rs3803662 could influence gastric cancer survival outcomes.

Methods

With multiplex SNaPshot method, we genotyped TOX3 rs3803662 in 880 gastric patients with surgical resection. The association between genotype and survival outcomes was performed by the Kaplan-Meier method, Cox regression analysis models and the log-rank test.

Results

There was no association in the analyses of rs3803662 and survival of gastric cancer. However, the stratified analysis by histology showed that rs3803662 CT/TT genotype was associated with a significantly better survival for diffuse-type gastric cancer (log-rank p = 0.030, hazard ratio [HR]  = 0.67, 95% confidence interval [CI]  = 0.46–0.96), than the CC genotype. In addition, this favorable effect was especially obvious among gastric cancer patients with tumor size >5 cm, T3 and T4 depth of invasion, lymph node metastasis, no drinking, no distant metastasis, no chemotherapy and gastric cardia cancer.

Conclusions

TOX3 rs3803662 might play an important role in the prognostic outcome and treatment of gastric cancer, especially perhaps further help in explaining the reduced risk of death associated with diffuse-type gastric cancer.

Protective role of Helicobacter pylori infection in prognosis of gastric cancer: evidence from 2,454 patients with gastric cancer

BACKGROUND

A number of studies have investigated the association between Helicobacter pylori (H. pylori) infection and the prognosis of gastric cancer (GC), with inconsistent and inconclusive results. We performed a meta-analysis to derive a more precise estimation of the association.

METHODOLOGY/PRINCIPAL FINDINGS

A systematic search of PubMed, EMBASE, Cochrane and Chinese wanfang databases was performed with the last search updated on February 19, 2013. The hazard ratio (HR) and its 95% confidence interval (95%CI) were used to assess the strength of association. A total of 12 studies including 2454 patients with GC were involved in this meta-analysis. The pooled HR was 0.71 (95%CI: 0.57-0.87; P = 0.001) for OS and 0.60 (95%CI: 0.30-1.18; P = 0.139) for DFS in GC patients, respectively. The protective role of H. pylori infection in the prognosis of GC was also observed among different subgroups stratified by ethnicity, statistical methodology, H. pylori evaluation method and quality assessment. There was no evidence of publication bias.

CONCLUSIONS/SIGNIFICANCE

This meta-analysis suggests a protective role for H. pylori infection in the prognosis of GC. The underlying mechanisms need to be further elucidated, which could provide new therapeutic approaches for GC.