Cancer stem cells in Helicobacter pylori infection and aging: Implications for gastric carcinogenesis

Factors associated with precancerous stomach lesions and progresion: A 7-year multi-center prospective cohort study on the low incidence of gastric cancer in central Saudi Arabia

BACKGROUND

In Saudi Arabia (SA) no data are available on precancerous stomach lesions (PSLs) or the associated risk factors. We aimed to identify PSLs and investigate factors associated with PSLs and their progression.

METHODS

This 7-year prospective study screened for PSLs in asymptomatic Saudi patients aged 45-75 years in central SA ( n = 35,640). Those who had high-sensitivity guaiac fecal occult blood tests (HSgFOBT+) and negative colonoscopy results ( n = 1242) were subjected to upper GI endoscopy to identify PSLs and were followed up every 3 years or earlier, depending on the type of PSL. Factors associated with PSLs were investigated.

RESULTS

The 7-year participation rate was 86.9% (1080/1242). The 7-year prevalence of PSLs was 30.9% (334/1080). The incidence rate of PSLs was 134 new cases/100,000 population/year, total population at risk - 35,640 and 44.3 new cases/1,000 persons/year among the 1080 participants with HSgFOBT+ and negative colonoscopy results. Among the 334 participants with PSLs, 8 (2.4%) had neoplastic progression to GC during the surveillance period. Age, Helicobacter pylori infection, smoking status, a diet with preserved salty foods, low income, and a family history of GC were associated with PSLs.

CONCLUSIONS

The incidence of GC is low in central SA, but screening for PSLs among participants with HSgFOBT+ and negative colonoscopy findings may contribute to the early detection and subsequent treatment of GC. HP eradication, not smoking, normal body weight, and adhering to a healthy diet seem to be potential factors associated with the development of PSLs. Further studies are needed to search if such interventions would decrease the incidence of PSLs and progression to early GC.

Helicobacter pylori induces the expression of Lgr5 and stem cell properties in gastric target cells

Helicobacter pylori infection predisposes carriers to a high risk of developing gastric cancer. The cell-of-origin of antral gastric cancer is the Lgr5+ stem cell. Here, we show that infection of antrum-derived gastric organoid cells with H. pylori increases the expression of the stem cell marker Lgr5 as determined by immunofluorescence microscopy, qRT-PCR, and Western blotting, both when cells are grown and infected as monolayers and when cells are exposed to H. pylori in 3D structures. H. pylori exposure increases stemness properties as determined by spheroid formation assay. Lgr5 expression and the acquisition of stemness depend on a functional type IV secretion system (T4SS) and at least partly on the T4SS effector CagA. The pharmacological inhibition or genetic ablation of NF-κB reverses the increase in Lgr5 and spheroid formation. Constitutively active Wnt/β-catenin signaling because of Apc inactivation exacerbates H. pylori-induced Lgr5 expression and stemness, both of which persist even after eradication of the infection. The combined data indicate that H. pylori has stemness-inducing properties that depend on its ability to activate NF-κB signaling.

Environmental and Genetic Risk Factors for Gastric Cancer

Gastric cancer is a heterogeneous and prevalent disease. The traditional environmental exposures associated with elevated risk of gastric cancer are less prevalent in the USA today. Genetic risks and risks associated with inflammation remain. Most cases are sporadic, and familial clustering is observed in about 10% of the cases. Hereditary gastric cancer accounts for a very low percentage of cases. Here we review the genetic and environmental risk factors associated with the disease. In addition, we will review screening guidelines and current modalities that are available for screening in high-risk populations.

Environmental and genetic risk factors for gastric cancer

Gastric cancer is a heterogeneous and prevalent disease. The traditional environmental exposures associated with an elevated risk of gastric cancer are less prevalent in the United States today. Genetic risks and risks associated with inflammation remain. Most cases are sporadic and familial clustering is observed in about 10% of the cases. Hereditary gastric cancer accounts for a very low percentage of cases. Here we review the genetic and environmental risk factors associated with the disease.

Impact of Cancer Stem Cells on Therapy Resistance in Gastric Cancer

Gastric cancer (GC) is the fourth leading cause of cancer death worldwide, with an average 5-year survival rate of 32%, being of 6% for patients presenting distant metastasis. Despite the advances made in the treatment of GC, chemoresistance phenomena arise and promote recurrence, dissemination and dismal prognosis. In this context, gastric cancer stem cells (gCSCs), a small subset of cancer cells that exhibit unique characteristics, are decisive in therapy failure. gCSCs develop different protective mechanisms, such as the maintenance in a quiescent state as well as enhanced detoxification procedures and drug efflux activity, that make them insusceptible to current treatments. This, together with their self-renewal capacity and differentiation ability, represents major obstacles for the eradication of this disease. Different gCSC regulators have been described and used to isolate and characterize these cell populations. However, at the moment, no therapeutic strategy has achieved the effective targeting of gCSCs. This review will focus on the properties of cancer stem cells in the context of therapy resistance and will summarize current knowledge regarding the impact of the gCSC regulators that have been associated with GC chemoradioresistance.

Aldehyde Dehydrogenase 1 in Gastric Cancer

Gastric cancer (GC) is a disease that threatens human health. It is thus crucial to clarify the mechanisms involved in GC development and discover diagnostic biomarkers and therapeutics. As a cancer stem cell marker, aldehyde dehydrogenase 1 (ALDH1) is involved in the development, progression, and treatment of GC. This review evaluated the prognostic value of ALDH1 and explored its mechanism of action in GC. Importantly, ALDH1 is an informative biomarker in clinical practice as it has specific relationships with indicators, such as metastasis and overall survival. Additionally, ALDH1 interacts with genes and exhibits properties that mimic stem cell characteristics amongst other mechanisms employed in the occurrence and progression of GC. Our results, therefore, provide evidence of possible clinical utility of ALDH1 as a GC therapeutic target.

Mechanisms of cancer stem cell senescence: Current understanding and future perspectives

Cancer stem cells (CSCs) are a small population of heterogeneous tumor cells with the capacity of self-renewal and aberrant differentiation for immortality and divergent lineages of cancer cells. In contrast to bulky tumor cells, CSCs remain less differentiated and resistant to therapy even when targeted with tissue-specific antigenic markers. This makes CSCs responsible for not only tumor initiation, development, but also tumor recurrence. Emerging evidence suggests that CSCs can undergo cell senescence, a non-proliferative state of cells in response to stress. While cell senescence attenuates tumor cell proliferation, it is commonly regarded as a tumor suppressive mechanism. However, mounting research indicates that CSC senescence also provides these cells with the capacity to evade cytotoxic effects from cancer therapy, exacerbating cancer relapse and metastasis. Recent studies demonstrate that senescence drives reprogramming of cancer cell toward stemness and promotes CSC generation. In this review, we highlight the origin, heterogeneity and senescence regulatory mechanisms of CSCs, the complex relationship between CSC senescence and tumor therapy, and the recent beneficial effects of senotherapy on eliminating senescent tumor cells.

Role of Helicobacter pylori infection in the manifestation of old age-related diseases

Helicobacter pylori is one of the most prevalent infection worldwide. It affects individuals of different age groups. Elderly people tend to resist eradication treatment and worsening of infection can lead to several gastric and non-gastric pathologies. Aging-associated cellular and molecular alteration can increase the risk of other pathologies such as osteoporosis, Alzheimer's disease, Parkinson's disease, respiratory and renal dysfunction, and cancer in geriatric patients, more than other age groups. This review article highlights some of the most common old age diseases and the role of H. pylori infection as a risk factor to worsen the conditions, presented by the molecular evidences of these associations. These studies can help clinicians to understand the underlying pathogenesis of the disease and identify high-risk patients, aiding clearer diagnosis and treatment.

Expression of ALDH1A1 and CD133 is associated with the prognosis and effect of different chemotherapeutic regimens in gastric cancer

Gastric cancer (GC) is one of the most common malignant tumors worldwide. Previous studies have reported that aldehyde dehydrogenase-1A1 (ALDH1A1) and cluster of differentiation (CD)-133 are considered to be cancer stem cell markers in GCs. The present study immunohistochemically examined the distribution and expression of two tumor stem cell markers, CD133 and ALDH1A1, in both primary tumors and para-tumor tissues. In 91 cases with stage III, 57 (62%) were positive for ALDH1A1 and 60 (66%) were positive for CD133. ALDH1A1 was detected in para-tumors and cancerous tissues of the stomach, and the immunoreactivity of the tumors was stronger than that in para-tumor tissues. CD133 was only detected in tumors. The expression of ALDH1A1 was significantly associated with advanced T/N stage (T stage, P=0.012; N stage, P=0.023) and poor differentiation (P=0.020), while CD133 was associated with advanced T stage (P=0.007). Univariate and multivariate Cox proportional hazards analysis revealed that tumor stage, CD133 expression, vascular invasion and sex were independent predictors of disease-free survival (DFS) time, and tumor size, vascular invasion and sex were independent predictors of overall survival (OS) time in patients with GC. Patients with CD133⁺ GC had poorer DFS (P=0.042), while ALDH1A1⁺ GC was not associated with poorer DFS. In regard to chemotherapy, improvements in survival were not observed after the addition of taxane compared with two-drug therapy. However, the subgroup analysis indicated that in the ALDH1A1⁻ subgroup, and CD133⁺ and ALDH1A1⁻ subgroups, an increased OS was observed in two-drug therapy (P=0.043). The results of the present study indicate that ALDH1A1 and CD133 may play an important role in tumor invasion, metastasis and prognosis, and ALDH1A1⁻ expression does not benefit the taxane-based triple chemotherapeutic regimen in patients with GC.

Impact of age on stage-specific mortality in patients with gastric cancer: A long-term prospective cohort study

Controversies exist regarding the impact of age on gastric cancer-related mortality according to cancer stage. In our prospective cohort study, we evaluated the impact of age on stage-specific mortality in patients with gastric cancer. Between 2002 and 2006, patients with newly diagnosed gastric cancer were recruited from two university-affiliated hospitals in Korea. Follow-up data were updated regularly based on medical records and telephone surveys. Patients were classified into four subgroups according to age: <50, 50-59, 60-69, and 70-79 years. A total of 448 patients were followed up for 81.6 months (interquartile range, 25.0-139.3 months). The number of patients with stage I, II, III, and IV disease was 247, 74, 88, and 39, respectively. Overall, age was an independent risk factor for gastric cancer-specific mortality (hazard ratio [HR], [95% confidence interval (CI)]: 1.53 [0.91-2.57], 1.88 [1.21-2.91], and 2.64 [1.69-4.14] in the 50-59, 60-69, and 70-79 years groups, respectively, with the <50 years group as reference). In patients with stage I and II gastric cancer, the 70-79 years group was associated with a significantly higher rate of cancer-specific mortality than the <50 years group (stage I: HR [95% CI], 9.55 [2.11-43.12]; stage II: HR [95% CI], 7.17 [2.32-22.18]). However, age was not an independently associated factor for cancer-specific mortality in patients with stage III and IV gastric cancer. Although age was an independent risk factor for gastric cancer-related mortality in patients with gastric cancer, its impact may differ depending on the stage of cancer.

Chemoprevention of gastric cancer by Helicobacter pylori eradication and its underlying mechanism

The cascade of gastric cancer, a leading cause of cancer incidence and mortality, is multifactorial. Helicobacter pylori (HP) infection plays a major role in gastric cancer (GC), and there has been an accumulation of data regarding the chemopreventive effect of HP eradication. However, it remains unclear how HP infection causes GC and how HP eradication prevents GC. To clarify this issue, the following approaches were performed in this review article. First, how HP-induced atrophic gastritis (AG) and intestinal metaplasia (IM) provoke the development of GC is shown, followed by how long HP eradication takes to induce a reversible change in AG and IM. Second, epigenetic studies of PTPN6, MOS, DCC, CRK, and VAV1 were performed in noncancerous gastric specimens in terms of HP status. Among these genes, MOS was found to be a possible surrogate marker for GC development. HP eradication decreased aberrant DNA methylation in a gene-specific manner, and MOS played a role in metachronous gastric neoplasms. Third, transforming growth factor-β1 (TGF-β1) and TGF-β1-induced epithelial-mesenchymal transition (EMT) markers were investigated in gastric mucosa. HP infection triggered the TGF-β1-induced EMT pathway and caused the emergence of GC stem cells, such as CD44v8-10. When HP was eradicated, these two pathways were inhibited. Finally, a 2222 cohort study showed that HP eradication significantly decreased the risk of noncardiac GC. Taken together, HP eradication is effective as a primary GC prevention method, and its underlying mechanism includes reversibility of AG and IM, methylation, EMT, and stem cells.

Immunohistochemical Analysis of LGR5 and TROY Expression in Gastric Carcinogenesis Demonstrates an Inverse Trend

BACKGROUND

Two of the Wnt signaling pathway target genes, tumor necrosis factor receptor family member (TROY) and leucine-rich G-protein coupled receptor (LGR5), are involved in the generation and maintenance of gastrointestinal epithelium. A negative modulatory role has recently been assigned to TROY, in this pathway. Here, we have examined their simultaneous expression in gastric carcinogenesis.

METHODS

Tumor and paired adjacent tissues of intestinal-type gastric cancer (GC) patients (n = 30) were evaluated for LGR5 and TROY expression by immunohistochemistry. The combination of the percentage of positively¬ stained cells and the intensity of staining was defined as the composite score and compared between groups. The obtained findings were re-evaluated in a mouse model.

RESULTS

TROY expression in the tumor tissue was significantly lower than that of the adjacent tissue (2.5 ± 0.9 vs. 3.3 ± 0.9, p = 0.004), which was coincident with higher LGR5 expression (3.6 ± 1.1 vs. 2.7 ± 0.9, p = 0.001). This observation was prominent at stages II/III of GC, leading to a statistically significant mean difference of expression between these two molecules (p = 0.005). In the H. pylori infected-mouse model, this inverse expression was observed in transition from early (8-16 w) to late (26-50 w) time points, post treatment (p = 0.002).

CONCLUSION

Our data demonstrates an inverse trend between TROY down-regulation and LGR5 up-regulation in GC tumors, as well as in response to H. pylori infection in mice. These findings support a potential negative modulatory role for TROY on LGR5 expression.

Transcriptomic but not genomic variability confers phenotype of breast cancer stem cells

Background

Breast cancer stem cells (BCSCs) are considered responsible for cancer relapse and drug resistance. Understanding the identity of BCSCs may open new avenues in breast cancer therapy. Although several discoveries have been made on BCSC characterization, the factors critical to the origination of BCSCs are largely unclear. This study aimed to determine whether genomic mutations contribute to the acquisition of cancer stem-like phenotype and to investigate the genetic and transcriptional features of BCSCs.

Methods

We detected potential BCSC phenotype-associated mutation hotspot regions by using whole-genome sequencing on parental cancer cells and derived serial-generation spheres in increasing order of BCSC frequency, and then performed target deep DNA sequencing at bulk-cell and single-cell levels. To identify the transcriptional program associated with BCSCs, bulk-cell and single-cell RNA sequencing was performed.

Results

By using whole-genome sequencing of bulk cells, potential BCSC phenotype-associated mutation hotspot regions were detected. Validation by target deep DNA sequencing, at both bulk-cell and single-cell levels, revealed no genetic changes specifically associated with BCSC phenotype. Moreover, single-cell RNA sequencing showed profound transcriptomic variability in cancer cells at the single-cell level that predicted BCSC features. Notably, this transcriptomic variability was enriched during the transcription of 74 genes, revealed as BCSC markers. Breast cancer patients with a high risk of relapse exhibited higher expression levels of these BCSC markers than those with a low risk of relapse, thereby highlighting the clinical significance of predicting breast cancer prognosis with these BCSC markers.

Conclusions

Transcriptomic variability, not genetic mutations, distinguishes BCSCs from non-BCSCs. The identified 74 BCSC markers have the potential of becoming novel targets for breast cancer therapy.

Electronic supplementary material

The online version of this article (10.1186/s40880-018-0326-8) contains supplementary material, which is available to authorized users.

Dormancy activation mechanism of tracheal stem cells

Accurate markers and molecular mechanisms of stem cell dormancy and activation are poorly understood. In this study, the anti-cancer drug, 5-fluorouracil, was used to selectively kill proliferating cells of human bronchial epithelial (HBE) cell line. This method can enrich and purify stem cell population. The dormant versus active status of stem cells was determined by phosphorylation of RNAp II Ser2. The surviving stem cells were cultured to form stem cell spheres expressing stem cell markers and transplanted into nude mice to form a teratoma. The results demonstrated the properties of stem cells and potential for multi-directional differentiation. Bisulfite sequencing polymerase chain reaction showed that demethylation of the Sox2 promoter by 5-FU resulted in Sox2 expression in the dormant stem cells. This study shows that the dormancy and activation of HBE stem cells is closely related to epigenetic modification.

Regulation of Gastric Lgr5+ve Cell Homeostasis by Bone Morphogenetic Protein (BMP) Signaling and Inflammatory Stimuli

BACKGROUND & AIMS

Gastric Leucine-rich repeat-containing G-protein-coupled receptor 5 (Lgr5) cells exert important functions during injury and homeostasis. Bone morphogenetic protein (BMP) signaling regulates gastric inflammation and epithelial homeostasis. We investigated if BMP signaling controls the fate of Lgr5^+ve cells during inflammation.

METHODS

The H⁺/K⁺-adenosine triphosphatase β-subunit promoter was used to express the BMP inhibitor noggin (Nog) in the stomach (H⁺/K⁺-Nog mice). Inhibition of BMP signaling in Lgr5 cells was achieved by crossing Lgr5-EGFP-ires-CreERT2 (Lgr5-Cre) mice to mice with floxed alleles of BMP receptor 1A (Lgr5-Cre;Bmpr1a^flox/flox mice). Lgr5/GFP^+ve cells were isolated using flow cytometry. Lineage tracing studies were conducted by crossing Lgr5-Cre mice to mice that express Nog and tdTomato (Lgr5-Cre;H⁺/K⁺-Nog;Rosa26-tdTom). Infection with Helicobacter felis was used to induce inflammation. Morphology of the mucosa was analyzed by H&E staining. Distribution of H⁺/K⁺-adenosine triphosphatase-, IF-, Ki67-, CD44-, CD44v9-, and bromodeoxyuridine-positive cells was analyzed by immunostaining. Expression of neck and pit cell mucins was determined by staining with the lectins Griffonia (Bandeiraea) simplicifolia lectin II and Ulex europaeus agglutinin 1, respectively. Id1, Bmpr1a, Lgr5, c-Myc, and Cd44 messenger RNAs were measured by quantitative reverse-transcription polymerase chain reaction.

RESULTS

Lgr5-Cre;Bmpr1a^flox/flox mice showed diminished expression of Bmpr1a in Lgr5/GFP^+ve cells. Infection of Lgr5-Cre;Bmpr1a^flox/flox mice with H felis led to enhanced inflammation, increased cell proliferation, parietal cell loss, and to the development of metaplasia and dysplasia. Infected Lgr5-Cre;H⁺/K⁺-Nog;Rosa26-tdTom mice, but not control mice, showed the presence of tomato^+ve glands lining the lesser curvature that stained positively with Griffonia (Bandeiraea) simplicifolia lectin II and Ulex europaeus agglutinin 1, and with anti-IF, -CD44, -CD44v9, and -bromodeoxyuridine antibodies.

CONCLUSIONS

Inflammation and inhibition of BMP signaling activate Lgr5^+ve cells, which give rise to metaplastic, dysplastic, proliferating lineages that express markers of mucus neck and zymogenic cell differentiation.

Regulation of Gastric Metaplasia, Dysplasia, and Neoplasia by Bone Morphogenetic Protein Signaling

The bone morphogenetic proteins, (BMP)s are regulatory peptides that have significant effects on the growth and differentiation of gastrointestinal tissues. In addition, the BMPs have been shown to exert anti-inflammatory actions in the gut and to negatively regulate the growth of gastric neoplasms. The role of BMP signaling in the regulation of gastric metaplasia, dysplasia and neoplasia has been poorly characterized. Transgenic expression in the mouse stomach of the BMP inhibitor noggin leads to decreased parietal cell number, increased epithelial cell proliferation, and to the emergence of SPEM. Moreover, expression of noggin increases Helicobacter-induced inflammation and epithelial cell proliferation, accelerates the development of dysplasia, and it increases the expression of signal transducer and activator of transcription 3 (STAT3) and of activation-induced cytidine deaminase (AID). These findings provide new clues for a better understanding of the pathophysiological mechanisms that regulate gastric inflammation and the development of both dysplastic and neoplastic lesions of the stomach.

Dopamine receptor D2 is correlated with gastric cancer prognosis

It has been reported previously that a dopamine receptor D2 (DRD2) antagonist was able to induce cancer cell apoptosis and that DRD2 was expressed at high levels in pituitary adenomas. However, the expression of DRD2 in gastric cancer and its correlation with the prognosis of patients with gastric cancer remain to be elucidated. In the present study, the expression of DRD2 in 84 paired gastric cancer tissues and respective adjacent non-cancerous tissues were detected using an immunohistochemical assay. The correlation between the expression of DRD2 and the with survival durations of the patients with gastric cancer was analyzed using Kaplan-Meier analysis. In addition, online resources were utilized to further analyze the correlation between the mRNA expression level of DRD2 and prognosis. The effect of the DRD2 antagonist, thioridazine, on the proliferation of the AGS gastric cancer cells was determined. The results of the present study showed that the percentage of gastric cancer cases with a high expression level of DRD2 (51.2%) was higher, compared with that of cases with a low expression level of DRD2 (39.3%). Patients with a higher expression of DRD2 had shorter survival durations. The online database analysis revealed that the expression of DRD2 was also inversely correlated with the prognosis of patients with gastric cancer. Furthermore, the DRD2 antagonist, thioridazine, inhibited the growth of AGS gastric cancer cells. In conclusion, as the expression of DRD2 was negatively correlated with survival durations in patients with gastric cancer, it may be considered as a prognosis marker in the future. Developing DRD2 antagonists may assist in increasing the efficiency of cancer therapy.

Network analysis of common genes related to esophageal, gastric, and colon cancers

AIM

The aim of this study was to provide a biomarker panel for esophageal, gastric and colorectal cancers. It can help introducing some diagnostic biomarkers for these diseases.

BACKGROUND

Gastrointestinal cancers (GICs) including esophageal, gastric and colorectal cancers are the most common cancers in the world which are usually diagnosed in the final stages and due to heterogeneity of these diseases, the treatments usually are not successful. For this reason, many studies have been conducted to discover predictive biomarkers.

METHODS

In the present study, 507 genes related to esophageal, gastric and colon cancers were extracted.. The network was constructed by Cytoscape software (version 3.4.0). Then a main component of the network was analyzed considering centrality parameters including degree, betweenness, closeness and stress. Three clusters of the protein network accompanied with their seed nodes were determined by MCODE application in Cytoscape software. Furthermore, Gene Ontology (GO) analysis of the key genes in combination to the seed nodes was performed.

RESULTS

The network of 17 common differential expressed genes in three esophageal, gastric and colon adenocarcinomas including 1730 nodes and 9188 edges were constructed. Eight crucial genes were determined. Three Clusters of the network were analyzed by GO analysis.

CONCLUSION

The analyses of common genes of the three cancers showed that there are some common crucial genes including TP53, EGFR, MYC, AKT1, CDKN2A, CCND1 and HSP90AA1 which are tightly related to gastrointestinal cancers and can be predictive biomarkers for these cancers.

Expression of Leucine-rich Repeat-containing G-protein Coupled Receptor 5 and CD44: Potential Implications for Gastric Cancer Stem Cell Marker

BACKGROUND

The human leucine-rich repeat-containing G-protein coupled receptor (LGR) 5 and CD44 are one of the candidates for the marker of gastric cancer stem cells. We compared the expressions of two genes among control, dysplasia and cancer groups.

METHODS

We compared the mRNA expression of LGR5, CD44 and CD44v8-10 and immunohistochemistry (IHC) of LGR5 and CD44 in gastric antral mucosa of 45 controls, 36 patients with gastric dysplasia, and 39 patients with early gastric cancer. Additionally, IHC of LGR5 in gastric body mucosa was analyzed. Normal mucosa adjacent to dysplastic or cancer lesions was used for the quantitative real-time-PCR and IHC.

RESULTS

Immunoreactivity of LGR5 in base of antral mucosa was higher in non-cancerous tissues of cancer than those of control (P = 0.006), whereas the expression of LGR5 mRNA was not different among the three groups. Immunostaining of LGR5 was much stronger in the antrum than in the body of stomach (P < 0.001). Although there was no difference in antral immunointensity of LGR5 according to the severity of intestinal metaplasia, stronger immunostaining was found in the body with an aggravation of intestinal metaplasia (P trend < 0.001). The expression of CD44v8-10 mRNA was higher in cancer patients than control subjects and patients with dysplasia (P = 0.018 and 0.009) while the expression of CD44 mRNA was higher in the control groups than the others.

CONCLUSIONS

IHC of LGR5 in crypt base and CD44 may be used for gastric CSC markers. LGR5 expression may be associated with the developing of corporal intestinal metaplasia. The expression of CD44v8-10 mRNA would be more suitable for gastric cancer stem cell marker than CD44 or LGR5 mRNA.

Surface Antigen Profiling of Helicobacter pylori-Infected and -Uninfected Gastric Cancer Cells Using Antibody Microarray

BACKGROUND

Comprehensive immunophenotyping cluster of differentiation (CD) antigens in gastric adenocarcinoma, specifically between Helicobacter pylori-infected and -uninfected gastric cancer patients by using DotScan(™) antibody microarray has not been conducted. Current immunophenotyping techniques include flow cytometry and immunohistochemistry are limited to the use of few antibodies for parallel examination. We used DotScan(™) antibody microarray consisting 144 CD antibodies to determine the distribution of CD antigens in gastric adenocarcinoma cells and to elucidate the effect of H. pylori infection toward CD antigen expression in gastric cancer.

METHODS

Mixed leukocytes population derived from gastric adenocarcinoma patients were immunophenotyped using DotScan(™) antibody microarray. AGS cells were infected with H. pylori strains and cells were captured on DotScan(™) slides.

RESULTS

Cluster of differentiation antigens involved in perpetuating the tolerance of immune cells to tumor cells was upregulated in gastric adenocarcinoma cells compared to normal cells. CD279 which is essential in T cells apoptosis was found to be upregulated in normal cells. Remarkably, H. pylori-infected gastric cancer patients exhibited upregulated expression of CD27 that important in maintenance of T cells. Infection of cagA+ H. pylori with AGS cells increased CD antigens expression which involved in cancer stem cell while cagA- H. pylori polarized AGS cells to express immune-regulatory CD antigens. Increased CD antigens expression in AGS cells infected with cagA+ H. pylori were also detected in H. pylori-infected gastric cancer patients.

CONCLUSION

This study suggests the tolerance of immune system toward tumor cells in gastric cancer and distinct mechanisms of immune responses exploited by different H. pylori strains.

Correlation between FOXP3 expression and gastric cancer

The aim of the present study was to investigate the expression and function of forkhead box protein 3 (FOXP3) in gastric cancer using a rat model. A total of 92 Wistar rats were divided into two groups: An experimental group (n=46) and a control group (n=46). In the experimental group, sarcosine ethyl ester hydrochloride and sodium nitrite carcinogens were administered for 6 months to induce gastric cancer, whereas the control group was administered saline. Reverse transcription-polymerase chain reaction, immunoblotting, immunohistochemistry and western blotting were applied to analyze FOXP3 expression in gastric cancer and normal gastric tissue in the experimental and control groups, respectively. The association between FOXP3 expression and gastric cancer pathogenesis was investigated. In the experimental group, 6/46 rats developed hyperplastic lesions (grade I), 8 rats developed precancerous lesions (grade II), 18 rats developed early stage gastric cancer (grade III) and 14 rats developed gastrointestinal invasive carcinoma (grade IV). FOXP3 transcription and expression was observed in all gastric tissues of the experimental group. FOXP3 transcription and expression levels were significantly higher in the experimental group than in the control group (P<0.05). Furthermore, in the experimental group, a higher lesion grade was associated with a higher level of FOXP3 transcription and expression (P<0.05). FOXP3 protein was predominantly distributed in the tumor nuclei of the gastric cancer tissues. In the 32 pathological slices of gastric cancer tissue obtained from the experimental group, 20 cases (62.50%) exhibited positive FOXP3 staining. In the hyperplastic (grade I) and precancerous gastric (grade II) tissues, 2 cases (33.33%) and 4 cases (50.00%) exhibited positive FOXP3 staining, respectively. However, no positive FOXP3 expression was identified in the 46 pathological gastric tissue slices obtained from the control group. In conclusion, the expression of FOXP3 exhibits a positive correlation with gastric lesion grade. Therefore, FOXP3 may exhibit an important function in the occurrence and development of gastric cancer.

The prognostic roles of ALDH1 isoenzymes in gastric cancer

Increased aldehyde dehydrogenase 1 (ALDH1) activity has been determined to be present in the stem cells of several kinds of cancers including gastric cancer (GC). Nevertheless, which ones of ALDH1's isoenzymes are leading to ALDH1 activity remains elusive. In this study, we examined the prognostic value and hazard ratio (HR) of individual ALDH1 isoenzymes in patients with GC using "The Kaplan-Meier plotter" database. mRNA high expression level of ALDH1A1 was not found to be significantly correlated with the overall survival (OS) of all patients with GC followed for 20 years, HR =0.86 (95% confidence interval [CI]: 0.7-1.05), P=0.13. mRNA high expression level of ALDH1A2 was also not significantly correlated with OS for all patients with GC, HR =1.13 (95% CI: 0.91-1.41), P=0.25. mRNA high expression level of ALDH1A3 was found to be significantly correlated with worsened OS in either intestinal-type patients, HR =2.24 (95% CI: 1.44-3.49), P=0.00026, or diffuse-type patients, HR =1.91 (95% CI: 1.02-3.59), P=0.04. Interestingly, mRNA high expression level of ALDH1B1 was found to be significantly correlated with better OS for all patients with GC, HR =0.66 (95% CI: 0.53-0.81), P=7.8e-05, and mRNA high expression level of ALDH1L1 was found to be significantly correlated with worsened OS for all patients with GC, HR =1.23 (95% CI: 1-1.51), P=0.048. Furthermore, our results also indicate that ALDH1A3 and ALDH1L1 are potential major contributors to the ALDH1 activity in GC, since mRNA high expression levels of ALDH1A3 and ALDH1L1 were found to be significantly correlated with worsened OS for all patients with GC. Based on our study, ALDH1A3 and ALDH1L1 are potential prognostic markers and therapeutic targets for patients with GC.

Mining distinct aldehyde dehydrogenase 1 (ALDH1) isoenzymes in gastric cancer

Aldehyde dehydrogenase 1 (ALDH1) consists of a family of intracellular enzymes, highly expressed in stem cells populations of leukemia and some solid tumors. Up to now, 6 isoforms of ALDH1 have been reported. However, the expression patterns and the identity of ALDH1 isoenzymes contributing to ALDH1 activity, as well as the prognostic values of ALDH1 isoenzymes in cancers all remain to be elucidated. Here, we studied the expressions of ALDH1 transcripts in gastric cancer (GC) compared with the normal controls using the ONCOMINE database. Through the Kaplan-Meier plotter database, which contains updated gene expression data and survival information of 876 GC patients, we also investigated the prognostic values of ALDH1 isoenzymes in GC patients. It was found that when compared with normal tissues, ALDH1A1 mRNA expression was downregulated, whereas ALDH1A3 and ALDH1B1 were upregulated in GC patients. In survival analyses, high ALDH1A1 and ALDH1B1 expressions were associated with better overall survival (OS) in all GC patients. In addition, high transcription activity of ALDH1A1 predicted better OS in gastric intestinal type adenocarcinoma, but not in diffuse gastric adenocarcinoma. GC patients with high mRNA level of ALDH1B1 showed better OS in gastric intestinal type, and worse OS in diffuse type. Oppositely, high transcription activities of ALDH1A2, ALDH1A3 and ALDH1L1 predicted worsen overall survival in GC patients, suggesting that these isoenzymes might be responsible mainly for the ALDH1 activities in GC. These data provides ALDH1A2, ALDH1A3 and ALDH1L1 as excellent potential targets for individualized treatment of GC patients.

Role of cancer stem cells in racial disparity in colorectal cancer

Although African‐Americans (AAs) have a higher incidence of colorectal cancer (CRC) than White people, the underlying biochemical mechanisms for this increase are poorly understood. The current investigation was undertaken to examine whether differences in self‐renewing cancer stem/stem‐like cells (CSCs) in the colonic mucosa, whose stemness is regulated by certain microRNAs (miRs), could partly be responsible for the racial disparity in CRC. The study contains 53 AAs and 47 White people. We found the number of adenomas and the proportion of CD44⁺CD166⁻  CSC phenotype in the colon to be significantly higher in AAs than White people. MicroRNAs profile in CSC‐enriched colonic mucosal cells, expressed as ratio of high‐risk (≥3 adenomas) to low‐risk (no adenoma) CRC patients revealed an 8‐fold increase in miR‐1207‐5p in AAs, compared to a 1.2‐fold increase of the same in White people. This increase in AA was associated with a marked rise in lncRNA PVT1 (plasmacytoma variant translocation 1), a host gene of miR‐1207‐5p. Forced expression of miR‐1207‐5p in normal human colonic epithelial cells HCoEpiC and CCD841 produced an increase in stemness, as evidenced by morphologically elongated epithelial mesenchymal transition( EMT) phenotype and significant increases in CSC markers (CD44, CD166, and CD133) as well as TGF‐β, CTNNB1, MMP2, Slug, Snail, and Vimentin, and reduction in Twist and N‐Cadherin. Our findings suggest that an increase in CSCs, specifically the CD44⁺CD166⁻ phenotype in the colon could be a predisposing factor for the increased incidence of CRC among AAs. MicroRNA 1207‐5p appears to play a crucial role in regulating stemness in colonic epithelial cells in AAs.

Mortality trends and years of potential life lost from gastric cancer in Mexico, 2000-2012

BACKGROUND

In 2013 in Mexico, gastric cancer (GC) was the third leading cause of death from cancer in individuals 20 years of age or older. GC remains a public health problem in Mexico due to its high mortality and low survival rates, and the significantly lower quality of life of patients with this condition.

OBJECTIVES

The aims of this study were to determine mortality trends nationwide, by state and socioeconomic region, and to determine rates of age-adjusted years of potential life lost due to GC, by state and socioeconomic region, within the period of 2000-2012.

METHODS

Mortality records associated with GC for 2000-2012 were obtained from the National Health Information System of the Mexican Department of Health. Codes from the Tenth Revision of the International Classification of Diseases corresponding to the basic cause of death from GC were identified. Mortality and age-adjusted years of potential life lost rates, by state and socioeconomic region, were also calculated.

RESULTS

In Mexico, 69,107 individuals died from GC within the time frame of 2000-2012. The age-adjusted mortality rate per 100,000 inhabitants decreased from 7.5 to 5.6. The male:female ratio was 1.15:1.0. Chiapas had the highest death rate from GC (9.2, 95% CI 8.2-10.3 [2000] and 8.2, 95% CI 7.3-9 [2012]), as well as regions 1, 2, and 5. Chiapas and socioeconomic region 1 had the highest rate of years of potential life lost.

CONCLUSIONS

Using the world population age distribution as the standard, the age-adjusted mortality rate in Mexico per 100,000 inhabitants that died from GC decreased from 7.5 to 5.6 between 2000 and 2012. Chiapas and socioeconomic regions 1, 2, and 5 had the highest mortality from GC (Chiapas: 9.2, 95% CI 8.2-10.3 [2000] and 8.2, 95% CI 7.3-9 [2012], region 1: 5.5, 95% CI 5.2-5.9 [2000] and 5.3, 95% CI 4.9-5.7 [2012]; region 2: 5.3, 95% CI 5-5.6 [2000] and 5.4, 95% CI 5.1-5.8 [2012]; region 5: 6.1, 95% CI 5.6-6.6 [2000] and 4.6, 95% CI 4.2-5 [2012]). Chiapas and socioeconomic region 1 had the highest rate of years of potential life lost (Chiapas: 97.4 [2000] and 79.6 [2012] and region 1: 73.5 [2000] 65 [2012]).

The JAK/STAT signaling cascade in gastric carcinoma (Review)

Gastric carcinoma remains one of the most prevalent forms of cancer worldwide, despite the decline in incidence rates, increased awareness of the disease and advancement in treatment strategies. Helicobacter pylori infection, dietary factors, lifestyle influences and various genetic aberrations have been shown to contribute to the development and progression of gastric cancer. Recent studies on the genomic landscape of gastric adenocarcinoma have identified several key signaling molecules, including epidermal growth factor receptor family (ErbB) members, vascular endothelial growth factor receptor family (VEGFR) members and PI3K/Akt/mTOR pathway components, that have been implicated in the molecular pathogenesis of gastric cancers. However, clinical trials with compounds that target these molecules have failed to show a significant improvement in overall survival rates when supplemented with conventional therapies. Therefore, it is essential to identify effective prognostic and/or diagnostic biomarkers and develop molecular targeted therapies. The JAK/STAT cascade is a principal signal transduction pathway in cytokine and growth factor signaling, regulating various cellular processes such as cell proliferation, differentiation, migration and survival. Numerous in vivo and in vitro studies have shown that dysregulated JAK/STAT signaling is a driving force in the pathogenesis of various solid cancers as well as hematopoietic malignancies. Hence, a large number of preclinical and clinical studies of drugs targeting this pathway are currently underway. Notably, aberrant JAK/STAT signaling has also been implicated in gastric cancers. In this review, we focus on the ongoing research on the JAK/STAT cascade in gastric carcinoma and discuss the therapeutic potential of targeting JAK/STAT signaling for the treatment of gastric cancer.

PSCA rs2294008 Polymorphism with Increased Risk of Cancer

BACKGROUND

Published data on the association between PSCA rs2294008 polymorphism and cancer risk have implicated inconclusive results. To determine the relationship and to precisely assess the effect size estimate of the association, we performed a meta-analysis.

METHODS

We searched published literature in Embase and PubMed databases using the search terms "PSCA", "prostate stem cell antigen", "variants", "polymorphism", "polymorphisms", and "cancer". A total of 21 eligible articles were retrieved, with 27, 197 cancer cases and 48, 237 controls.

RESULTS

On the whole, we found the association between PSCA rs2294008 polymorphism and cancer risk was statistically significant: TT vs CC: OR = 1.18, 95% CI, 1.10 to 1.27; TT + CT vs CC: OR = 1.08, 95% CI, 1.05 to 1.10; TT vs CT + CC: OR = 1.14, 95% CI, 1.07 to 1.21; T vs C: OR = 1.10, 95% CI, 1.06 to 1.14; CT vs CC: OR = 1.10, 95% CI, 1.06 to 1.13. Stratified analyses in cancer type and ethnicity showed similar results.

CONCLUSIONS

Based on the statistical evidence, we can draw a conclusion that the rs2294008 polymorphism of PSCA gene is likely to play a role in cancer carcinogenesis, especially in gastric cancer and bladder cancer.