Current perspectives and trends of CD39-CD73-eAdo/A2aR research in tumor microenvironment: a bibliometric analysis.

Background and objective: Extracellular adenosine (eAdo) bridges tumor metabolism and immune regulation. CD39-CD73-eAdo/A2aR axis regulates tumor microenvironment (TME) and immunotherapy response. In the era of immunotherapy, exploring the impact of the CD39-CD73-eAdo/A2aR axis on TME and developing targeted therapeutic drugs to enhance the efficacy of immunotherapy are the current research hotspots. This study summarizes and explores the research trends and hotspots of the adenosine axis in the field of TME to provide ideas for further in-depth research. Methods: Literature information was obtained from the Web of Science core collection database. The VOS viewer and the bibliometric tool based on R were used to quantify and identify cooperation information and individual influence by analyzing the detailed information of the global annual publication volume, country/region and institution distribution, article authors and co-cited authors, and journal distribution of these articles. At the same time, the distribution of author keywords and the co-occurrence of author keywords, highly cited articles, and highly co-cited references of CD39-CD73-eAdo/A2aR in the field of TME were analyzed to determine research hotspots and trends. Result: 1,721 articles published in the past ten years were included in this study. Through bibliometric analysis, we found that (1) 69 countries and regions explored the effect of the CD39-CD73-eAdo/A2aR on TME, and the research was generally on the rise. Researchers in the United States dominated research in this area, with the highest total citation rate. China had the most significant number of publications. (2) Harvard University has published the most articles in this field. (3) 12,065 authors contributed to the publication of papers in this field, of which 23 published at least eight papers. STAGG J had significant academic influence, with 24 published articles and 2,776 citations. Co-cited authors can be clustered into three categories. Stagg J, Allard B, Ohta A, and Antonioli, L occupied a central position in the network. (4) 579 scholarly journals have published articles in this field. The journal FRONTIERS IN IMMUNOLOGY published the most significant number of papers, with 97 articles and a total of 2,317 citations, and the number of publications increased year by year. (5) "The ectonucleotidases CD39 and CD73: Novel checkpoint inhibitor targets" was the most frequently local cited article (163 times). The "A2A adenosine receptor protects tumors from antitumor T cells" was the most co-cited reference (224 times). (6) Through the analysis of author keywords, we found that the relationship between adenosine and immunotherapy was a core concept for many researchers in this field. Breast cancer, melanoma, colorectal cancer, ovarian cancer, glioblastoma, pancreatic cancer, hepatocellular carcinoma, and lung cancer were the most frequent cancer types in adenosine-related tumor studies. Immunotherapy, immunosuppression, immune checkpoint, and immune checkpoint inhibitors were the hot keywords in the research, reflecting the importance of the adenosine metabolic pathway in tumor immunotherapy. The keywords such as Immunogenic cell death, T cells, Sting, regulatory T cells, innate immunity, and immune infiltration demonstrated the pathways by which adenosine affected the TME. The famous author keywords in recent years have been immunotherapy, immunogenic cell death, inflammation, lung cancer, and gastric cancer. Conclusion: The effect of CD39-CD73-eAdo/A2aR on the infiltration and function of various immune cells in TME, tumor immunotherapy response, and patient prognosis has attracted the attention of researchers from many countries/regions. American scholars still dominate the research in this field, but Chinese scholars produce the most research results. The journal FRONTIERS IN IMMUNOLOGY has published the wealthiest research in the field. Stagg J was a highly influential researcher in this field. Further exploration of targeted inhibition of CD39-CD73-eAdo/A2aR alone or in combination with other immunotherapy, radiotherapy, and chemotherapy in treating various cancer types and developing effective clinical therapeutic drugs are continuous research hotspots in this field.

FTO plays a crucial role in gastrointestinal cancer and may be a target for immunotherapy: an updated review.

Gastrointestinal cancer is a common malignancy with high mortality and poor prognosis. Therefore, developing novel effective markers and therapeutic targets for gastrointestinal cancer is currently a challenging and popular topic in oncology research. Accumulating studies have reported that N6-methyladenosine is the most abundant epigenetic modification in eukaryotes. N6-methyladenosine plays an essential role in regulating RNA expression and metabolism, including splicing, translation, stability, decay, and transport. FTO, the earliest demethylase discovered to maintain the balance of N6-adenosine methylation, is abnormally expressed in many tumors. In this review, we discuss the molecular structure and substrate selectivity of FTO. we focus on the role of FTO in gastrointestinal tumor proliferation, migration, invasion, apoptosis, autophagy, immune microenvironment, and its molecular mechanisms. We also discuss its potential in the treatment of gastrointestinal cancers.

Development and validation of nomogram models to predict radiotherapy or chemotherapy benefit in stage III/IV gastric adenocarcinoma with surgery.

Objectives: The advanced gastric adenocarcinoma (GAC) patients (stage III/IV) with surgery may have inconsistent prognoses due to different demographic and clinicopathological factors. In this retrospective study, we developed clinical prediction models for estimating the overall survival (OS) and cancer-specific survival (CSS) in advanced GAC patients with surgery. Methods: A retrospective analysis was conducted using the Surveillance, Epidemiology, and End Results (SEER) database. The total population from 2004 to 2015 was divided into four levels according to age, of which 179 were younger than 45 years old, 695 were 45-59 years old, 1064 were 60-74 years old, and 708 were older than 75 years old. There were 1,712 men and 934 women. Univariate and multivariate Cox regression analyses were performed to identify prognostic factors for OS and CSS. Nomograms were constructed to predict the 1-, 3-, and 5-year OS and CSS. The models' calibration and discrimination efficiency were validated. Discrimination and accuracy were evaluated using the consistency index, area under the receiver operating characteristic curve, and calibration plots; and clinical usefulness was assessed using decision curve analysis. Cross-validation was also conducted to evaluate the accuracy and stability of the models. Prognostic factors identified by Cox regression were analyzed using Kaplan-Meier survival analysis. Results: A total of 2,646 patients were included in our OS study. Age, primary site, differentiation grade, AJCC 6th_TNM stage, chemotherapy, radiotherapy, and number of regional nodes examined were identified as prognostic factors for OS in advanced GAC patients with surgery (P < 0.05). A total of 2,369 patients were included in our CSS study. Age, primary site, differentiation grade, AJCC 6th_TNM stage, chemotherapy, radiotherapy, and number of regional nodes examined were identified as risk factors for CSS in these patients (P < 0.05). These factors were used to construct the nomogram to predict the 1-, 3-, and 5-year OS and CSS of advanced GAC patients with surgery. The consistency index and area under the receiver operating characteristic curve demonstrated that the models effectively differentiated between events and nonevents. The calibration plots for 1-, 3-, and 5-year OS and CSS probability showed good consistence between the predicted and the actual events. The decision curve analysis indicated that the nomogram had higher clinical predictive value and more significant net gain than AJCC 6th_TNM stage in predicting OS and CSS of advanced GAC patients with surgery. Cross-validation also revealed good accuracy and stability of the models. Conclusion: The developed predictive models provided available prognostic estimates for advanced GAC patients with surgery. Our findings suggested that both OS and CSS can benefit from chemotherapy or radiotherapy in these patients.

ALDH1A1 in Cancers: Bidirectional Function, Drug Resistance, and Regulatory Mechanism.

Aldehyde dehydrogenases 1 family member A1(ALDH1A1) gene codes a cytoplasmic enzyme and shows vital physiological and pathophysiological functions in many areas. ALDH1A1 plays important roles in various diseases, especially in cancers. We reviewed and summarized representative correlative studies and found that ALDH1A1 could induce cancers via the maintenance of cancer stem cell properties, modification of metabolism, promotion of DNA repair. ALDH1A1 expression is regulated by several epigenetic processes. ALDH1A1 also acted as a tumor suppressor in certain cancers. The detoxification of ALDH1A1 often causes chemotherapy failure. Currently, ALDH1A1-targeted therapy is widely used in cancer treatment, but the mechanism by which ALDH1A1 regulates cancer development is not fully understood. This review will provide insight into the status of ALDH1A1 research and new viewpoint for cancer therapy.

Iron Catalyzed Cascade Construction of Molybdenum Carbide Heterointerfaces for Understanding Hydrogen Evolution.

The intercrystalline interfaces have been proven vital in heterostructure catalysts. However, it is still challenging to generate specified heterointerfaces and to make clear the mechanism of a reaction on the interface. Herein, this work proposes a strategy of Fe-catalyzed cascade formation of heterointerfaces for comprehending the hydrogen evolution reaction (HER). In the pure solid-phase reaction system, Fe catalyzes the in situ conversion of MoO2 to MoC and then Mo2 C, and the consecutive formation leaves lavish intercrystalline interfaces of MoO2 -MoC (in Fe-MoO2 /MoC@NC) or MoC-Mo2 C (in Fe-MoC/ß-Mo2 C@NC), which contribute to HER activity. The improved HER activity on the interface leads to further checking of the mechanism with density functional theory calculation. The computation results reveal that the electroreduction (Volmer step) produced H* prefers to be adsorbed on Mo2 C; then two pathways are proposed for the HER on the interface of MoC-Mo2 C, including the single-molecular adsorption pathway (Rideal mechanism) and the bimolecular adsorption pathway (Langmuir-Hinshelwood mechanism). The calculation results further show that the former is favorable, and the reaction on the MoC-Mo2 C heterointerface significantly lowers the energy barriers of the rate-determining steps.

Identification of immunophenotypes in esophageal squamous cell carcinoma based on immune gene sets.

PURPOSE: Esophageal squamous cell carcinoma (ESCC) is a malignant tumor with high heterogeneity. Research on molecular mechanisms involved in the process of tumor origination and progression is extremely limited to investigating mechanisms of molecular typing for ESCC. METHODS: After comprehensively analyzing the gene expression profiles in The Cancer Genome Atlas and Gene Expression Omnibus databases, we identified four immunotypes of ESCC (referred to as C1-C4) based on the gene sets of 28 immune cell subpopulations. The discrepancies in prognostic value, clinical features, drug sensitivity, and tumor components between the immunotypes were individually analyzed. RESULTS: The ranking of immune infiltration is C1 > C4 > C3 > C2. These subtypes are characterized by high and low expression of immune checkpoint proteins, enrichment and insufficiency of immune-related pathways, and differential distribution of immune cell subgroups. Poorer survival was observed in the C1 subtype, which we hypothesized could be caused by an immunosuppressive cell population. Fortunately, C1's susceptibility to anti-PD-1 therapy offers hope for patients with poor prognosis in advanced stages. On the other hand, C4 is sensitive to docetaxel, which may offer novel treatment strategies for ESCC in the future. It is worth noting that immunophenotyping is tightly bound to the abundance of stromal components and stem cells, which could explain the tumor immune escape to some extent. Ultimately, determination of hub genes based on the C1 subtypes provides a reference for the discovery of immunotarget drugs against ESCC. CONCLUSION: The identification of immunophenotypes in our study provides new therapeutic strategies for patients with ESCC.

The Association of Trefoil Factors with Gastric Cancer and Premalignant Lesions: A Cross-Sectional Population-Based Cohort Study.

BACKGROUND: A lack of research on the association of trefoil factors (TFF) with gastric cancer and premalignant lesions (PML) in the general population is an important obstacle to the application of TFFs for gastric cancer screening. We aimed to analyze the association of TFFs with gastric cancer and PMLs in a general population. METHODS: We evaluated 3,986 adults residing in Wuwei, China. We collected baseline characteristics and gastric cancer risk factors, including TFFs, endoscopic diagnosis, and pathologic information. Three logistic regression models were generated to analyze the association between TFFs and gastric cancer, as well as PMLs. Adjusted odds ratio (OR) and 95% confidence intervals (95% CI) were calculated to determine the strength of association. RESULTS: Compared with pepsinogen (PG) and anti-Helicobacter pylori immunoglobulin G antibody (Hp-IgG), TFFs had significant association with gastric cancer and PMLs after adjusting for biomarkers and risk factors (P < 0.05). The ORs (95% CI) for TFF1 (1.67; 1.27-2.20), TFF2 (2.66; 2.01-3.51), and TFF3 (1.32; 1.00-1.74) were larger than the ORs for PGI (0.79; 0.61-1.03), PGI/II (1.00; 0.76-1.31), and Hp-IgG (0.99; 0.73-1.35) in the gastric cancer group. In the intestinal metaplasia (IM) group, not only the TFF3 serum level was the highest, but also the OR (1.92; 1.64-2.25) was the highest. CONCLUSIONS: TFFs were associated with risk of gastric cancer and PMLs. IMPACT: Serum TFFs can improve the screening of high-risk populations for gastric cancer.

[Corrigendum] COX­2 regulates E­cadherin expression through the NF­κB/Snail signaling pathway in gastric cancer.

Following the publication of the above article, an interested reader drew to the author's attention that Fig. 4 contained a duplication error, which arose during the assembly of the figure; specifically, the upper-left panel in Fig. 4, showing the result of the 'Control in 12 h' experiment, was inadvertently repeated with the 'Control in 48 h' panel. The corrected version of Fig. 4, showing the correct data for the 'Control in 12 h' experiment, is shown below. The authors can confirm that this error does not change either the interpretation or the original conclusions of this study. The authors are grateful to the Editor of International Journal of Molecular Medicine for granting them the opportunity to publish the Corrigendum, and all the authors agree with this correction. Furthermore, the authors apologize to the readership for any inconvenience caused. [the original article was published in International Journal of Molecular Medicine 32: 93­100, 2013; DOI: 10.3892/ijmm.2013.1376].

Risk factors in the development of gastric adenocarcinoma in the general population: A cross-sectional study of the Wuwei Cohort.

Several risk factors have been identified for the development of gastric adenocarcinoma (GAC), where the control group was usually a healthy population. However, it is unclear at what stage known risk factor exert their influence toward the progression to cancer. Based on the Wuwei Cohort, we enrolled 1,739 patients with chronic non-atrophic gastritis (no-CAG), 3,409 patients with chronic atrophic gastritis (CAG), 1,757 patients with intestinal metaplasia (IM), 2,239 patients with low-grade dysplasia (LGD), and 182 patients with high-grade dysplasia (HGD) or GAC to assess the risk factors between each two consecutive stages from no-CAG to GAC/HGD using adjusted logistic regression. We found that different groups of risk factors were associated with different stages. Age, occupation of farmer, low annual family income, Helicobacter pylori (H. pylori) infection, drinking, eating hot food, histories of gastritis and peptic ulcer were associated with the development of CAG. Age, illiteracy, H. pylori infection, smoking, eating hot food, eating quickly, and histories of gastritis and gallbladder diseases were associated with the progression to IM from CAG. Male, occupation of farmer and history of peptic ulcer were associated with the development of LGD from IM. Age, male and polyp history appeared to be risk factors associated with the development of GAC/HGD from LGD. In conclusion, it seems that most risk factors function more as a set of switches that initiated the GAC carcinogenesis. H. Pylori eradication and control of other risk factors should be conducted before IM to decrease the incidence of GAC.

Prevalence and associated risk factors of Helicobacter pylori infection in the Wuwei cohort of north-western China.

OBJECTIVES: To evaluate the prevalence of Helicobacter pylori infection and risk factors and to serotype the strains in Wuwei, located in north-western China, which has a high incidence of gastric cancer. METHODS: Helicobacter pylori infection was analysed in 21 291 adults by 14 C-urea breath test, and H. pylori antibody were detected in 9183 serum samples by latex immunoturbidimetric method. The correlation of H. pylori infection with demographic-economic, lifestyle factors and medical history among the participants was determined by questionnaire. The antibodies against H. pylori urease, VacA and CagA in serum were determined by dot immunobinding assay. RESULTS: The infection rate of H. pylori was 53.0%, and 90.1% of strains were type I strains. The H. pylori infection rate was higher among farmers (OR = 1.34, 95% CI: 1.19-1.50) and individuals who had a junior high school or higher education level (OR = 1.10, 95% CI: 1.06-1.15), and was lower in older individuals (OR = 0.86, 95% CI: 0.83-0.90), individuals with high income (OR = 0.93, 95% CI: 0.90-0.95), individuals with a habit of eating quickly (OR = 0.93, 95% CI: 0.87-0.99) and individuals who consumed more fruit and vegetables (OR = 0.90, 95% CI: 0.85-0.95). Individuals with history of cholecystitis/cholecystolithiasis, hypertension and asthma were negatively correlated with H. pylori infection (P < 0.05). CONCLUSION: The prevalence of H. pylori infection is high in Wuwei. The major prevalent strain is type I strain. Age, education, occupation, household income, consumption of fruit and vegetables, and habit of eating quickly are independent risk factors for H. pylori infection, which is also associated with individuals with a history of extragastric diseases.

OBJECTIFS: Evaluer la prévalence de l'infection à Helicobacter pylori et les facteurs de risque et déterminer le sérotype des souches à Wuwei, situé dans le nord-ouest de la Chine, où l'incidence du cancer gastrique est élevée. MÉTHODES: L'infection à H. pylori a été analysée chez 21.291 adultes par un test respiratoire à l'urée au 14 C, et des anticorps à H. pylori ont été détectés dans 9.183 échantillons de sérum par une méthode immuno-turbidimétrique au latex. La corrélation entre l'infection à H. pylori et les facteurs démographiques et économiques, le mode de vie et les antécédents médicaux des participants a été déterminée par un questionnaire. Les anticorps contre l'uréase de H. pylori, VacA et CagA dans le sérum ont été déterminés par un test dot par d'immuno-liaison. RÉSULTATS: Le taux d'infection à H. pylori était 53,0% et 90,1% des souches étaient du type I. Le taux d'infection à H. pylori est plus élevé chez les agriculteurs (OR = 1,34 ; IC95%: 1,19 à 1,50) et les personnes qui avaient un niveau d'instruction du premier cycle secondaire ou supérieur (OR = 1,10 ; IC95%: 01,06 à 01,15) et était plus faible chez les personnes âgées (OR = 0,86 ; IC95%: 0,83-0,90), les personnes à revenu élevé (OR = 0,93 ; IC95%: 0,90-0,95), les personnes ayant l'habitude de manger rapidement (OR = 0,93 ; IC9 %: 0,87-0,99) et les individus qui consommaient plus de fruits et de légumes (OR = 0,90 ; IC95%: 0,85-0,95). Les personnes ayant des antécédents de cholécystite/cholécystolithiase, d'hypertension et d'asthme avaient une corrélation négative avec l'infection à H. pylori (p <0,05 ). CONCLUSION: La prévalence de l'infection à H. pylori est élevée à Wuwei. La principale souche répandue est du type I. L'âge, l'éducation, la profession, le revenu du ménage, la consommation de fruits et de légumes et l'habitude de manger rapidement sont des facteurs de risque indépendants d'infection à H. pylori, qui est également associée à des personnes ayant des antécédents de maladies extra-gastriques.

Prognostic value of NEK2 overexpression in digestive system cancers: a meta-analysis and systematic review.

BACKGROUND AND OBJECTIVE: Many studies have reported that NEK2 is overexpressed in digestive system cancers (DSCs) and is also correlated with patient survival. We performed a meta-analysis to comprehensively evaluate the prognostic role of NEK2 expression in DSCs. MATERIALS AND METHODS: A comprehensive literature search was performed using PubMed, EMBASE, and Web of Science. Synthesized hazard ratios (HRs) and odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the influence of NEK2 overexpression on the prognosis and clinicopathological features of patients with DSCs. RESULTS: A total of 13 studies involving 1,917 patients was included. Overall, patients with high NEK2 expression had poorer overall survival (HR =1.45; 95% CI: 1.15-1.83; P=0.002) and disease-free survival/recurrence-free survival (HR =2.28; 95% CI: 1.54-3.37; P<0.0001). Furthermore, subgroup analysis also suggested that elevated NEK2 expression was associated with poorer overall survival in patients with hepatocellular carcinoma (HR =1.45; 95% CI: 1.05-2.00; P=0.02) and colorectal cancer (HR =2.03; 95% CI: 1.16-3.54; P=0.01). Additionally, NEK2 overexpression was also associated with pretreatment serum AFP level (OR =1.79; 95% CI: 1.23-2.61; P<0.01) and portal vein thrombosis (OR =2.74; 95% CI: 1.22-6.17; P=0.01) in hepatocellular carcinoma. CONCLUSION: NEK2 might act as a useful prognostic predictor and a potential therapeutic target in DSCs. However, multicenter homogeneous studies with larger sample sizes are needed to further confirm our findings owing to some limitations in our meta-analysis.

Identification and characterization of tumor suppressor and oncogenic miRNAs in gastric cancer.

The aim of the present study was to screen for and identify microRNAs (miRNAs/miRs) that are associated with gastric cancer and to clarify the role of these miRNAs in gastric cancer. Thus, the differential expression of a panel of miRNAs in two pairs of gastric cancer tissues and their matched adjacent healthy tissues was investigated by performing a microarray analysis. To verify the results of this screen, 56 gastric cancer tissues were analyzed for the selected miRNAs using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The association between the expression of a specific miRNA and the clinical data relating to the tissue samples [including age, gender, tumor size, tumor node metastasis (TNM) stage and lymph-node metastasis] were subsequently examined. A total of 31 differentially expressed miRNAs were identified in the miRNA array. Using RT-qPCR to verify these results, it was determined that 10 miRNAs exhibited high mRNA expression levels and 13 miRNAs exhibited a low expression in the gastric cancer tissue samples, while 8 miRNAs did not demonstrate an association with gastric cancer. Thus, the microarray and RT-qPCR results demonstrated 74.2% (23/31 miRNAs) agreement. The association between the 23 miRNAs and the clinicopathological characteristics of the gastric cancer samples was investigated. It was identified that the expression levels of miR-551b-3p, miR-133b, miR-100-5p and miR-363-3p were significantly downregulated in the gastric cancer tissues, and this downregulation was closely correlated with the degree of differentiation (i.e., tumor grade), TNM stage and lymph-node metastasis (P<0.05). By contrast, the expression of miR-215 was significantly upregulated in the gastric cancer tissues, and its expression level was correlated with tumor differentiation, TNM stage and lymph-node metastasis (P<0.05). Furthermore, miR-200a-3p was upregulated in the gastric cancer tissues and its expression was significantly more prevalent in male patients compared with female patients (P<0.05). miR-429 was upregulated in the gastric cancer tissues and its expression was significantly higher in patients who were >50 years of age (P<0.05). These data indicate that a number of these miRNAs may be important in the development of gastric cancer. In particular, miR-551b-3p, miR-133b, miR-100-5p and miR-363-3p may act as tumor suppressors in the development of gastric cancer. By contrast, miR-215 appears to exhibit oncogenic properties and promote the development of gastric cancer. In addition, the abnormal expression of miR-200a-3p may be associated with gender, while the abnormal expression of miR-429 may be associated with age in patients with gastric cancer. However, additional studies are required to delineate the underlying mechanisms of the association, and to explore their potential as valid biomarkers in the diagnosis, classification and prognosis of gastric cancer.

Synergistic effects of IAP inhibitor LCL161 and paclitaxel on hepatocellular carcinoma cells.

Inhibitor of Apoptosis Proteins (IAPs) are key regulators of apoptosis in hepatocellular carcinoma (HCC) and their expression is negatively correlated with patient survival. LCL161 is a small molecule inhibitor of IAPs that has potent antitumour activity in a range of solid tumours. In HCC, response to LCL161 therapy has shown to be mediated by Bcl-2 expression. In this study, we aim to determine whether LCL161 has any therapeutic potential in HCC. Protein expression was determined by Western blot. Cell proliferation was determined by Cell Proliferation ELISA and BrdU colorimetric assays. Apoptosis was determined by Annexin V assay. Cell cycle analysis was performed by staining cells with propidium iodide and analysed in a FACScan. Automated Cell Counter and phase contrast microscopy were used to determine the cell viability. We have found that LCL161 targets (cIAP1, cIAP2 and XIAP) were up-regulated in HCC tumours. Both high Bcl-2 expressing HuH7 cells and low Bcl-2 expressing SNU423 cells showed strong resistance to LCL161 therapy with significant effects on both apoptosis and cell viability only evident at LCL161 concentrations of ⩾100µM. At these doses there was significant inhibition of IAP targets, however there was also significant inhibition of off-target proteins including pERK and pJNK suggesting apoptosis caused by drug toxicity. However, when used in combination with paclitaxel in HuH7 and SNU423 cells, LCL161 had significant antiproliferative effects at doses as low as 2µM and this was independent of Bcl-2 expression. Thus, LCL161 may be a useful agent in combination with paclitaxel to treat liver tumours.

Interaction between cyclooxygenase-2, Snail, and E-cadherin in gastric cancer cells.

AIM: To investigate the mechanisms of how cyclooxygenase-2 (COX-2) regulates E-cadherin in gastric cancer cells. METHODS: COX-2 expression in human gastric cancer cell lines SGC-7901, BGC-823, MGC-803 and AGS were measured at the mRNA and protein level. COX-2 rich cell line SGC-7901 was chosen for subsequent experiments. siRNA mediated gene knockdown was used to investigate the impact of COX-2 on nuclear factor-κB (NF-κB), Snail, and E-cadherin in gastric cancer cells. Gene expression was determined by Western blot and real-time polymerase chain reaction. To analyze whether NF-κB inhibition could interrupt the modulatory effect of COX-2 or prostaglandin E2 (PGE2) on E-cadherin, gastric cancer cells were treated with celecoxib or PGE2, in the presence of NF-κB specific siRNA. RESULTS: Highest expression level of COX-2 was found in SGC-7901 cells, both at mRNA and protein levels. siRNA mediated down-regulation of COX-2 led to a reduced expression of NF-κB and Snail, but an increased expression of E-cadherin in SGC-7901 cells. siRNA mediated down-regulation of NF-κB also led to a reduced expression of E-cadherin and Snail in SGC-7901 cells. However, COX-2 expression did not alter after cells were treated with NF-κB specific siRNA in SGC-7901 cells. Treatment of SGC-7901 cells with celecoxib led to a reduced expression of Snail but an increased expression of E-cadherin. In contrast, treatment of SGC-7901 cells with PGE2 led to an increased Snail and a decreased E-cadherin. However, siRNA-mediated knockdown of NF-κB partially abolished the effect of celecoxib and PGE2 on the regulation of E-cadherin and Snail in SGC-7901 cells. CONCLUSION: COX-2 likely functions upstream of NF-κB and regulates the expression of E-cadherin via NF-κB/Snail signaling pathway in gastric cancer cells.

COX-2 regulates E-cadherin expression through the NF-κB/Snail signaling pathway in gastric cancer.

Cyclooxygenase-2 (COX-2) participates in cancer invasion and metastasis by decreasing the expression of E-cadherin. However, the molecular mechanisms through which COX-2 regulates E-cadherin expression and function have not yet been fully elucidated. The aim of this study was to investigate the possible molecular mechanisms through which COX-2 regulates E-cadherin expression in gastric cancer. The mRNA and protein expression of COX-2, nuclear factor-κB (NF-κB), Snail and E-cadherin was detected in gastric cancer cells by quantitative PCR and western blot analysis, respectively. The expression of these genes was also detected in healthy gastric mucosa and gastric cancer tissues by immunohistochemistry. We detected various levels of COX-2, nuclear factor-κB (NF-κB), Snail and E-cadherin expression in the normal gastric mucosa and cancer tissues; however, the expression patterns differed: the increased expression of COX-2, NF-κB and Snail was observed in the gastric cancer tissues, whereas there was a considerable reduction in E-cadherin expression in the cancer tissues compared to the normal gastric mucosa. The expression patterns of COX-2, NF-κB and Snail were similar. The increased expression of COX-2 in the gastric cancer tissues closely correlated with the increased expression of NF-κB and Snail, but inversely correlated with the expression of E-cadherin. Treatment of the SGC7901 cells (which express high levels of COX-2) with celecoxib, a COX-2 inhibitor, not only led to a marked dose- and time-dependent decrease in the expression of COX-2, NF-κB and Snail, but also led to a significant increase in the expression of E-cadherin, and this was associated with a reduction in cell invasion. By contrast, the same treatment did not alter the expression of these genes in another gastric cancer cell line, MGC803 (which barely expresses COX-2). These data suggest that COX-2 regulates the expression of E-cadherin through the NF-κB and Snail signaling pathway in gastric cancer.

Efficacy of using cancer stem cell markers in isolating and characterizing liver cancer stem cells.

Recent evidence suggests that a subset of hepatocellular carcinomas (HCCs) are derived from liver cancer stem cells (LCSCs). In order to isolate and characterize LCSCs, reliable markers that are specific to these cells are required. We evaluated the efficacy of a range of cancer stem cell (CSC) markers in isolating and characterizing LCSCs. We show that the most widely used CSC markers are not specific to LCSCs. By western analysis, protein expression of the common markers showed no significant difference between HCC tumor tissues and adjacent non-cancerous liver. Further, isolation of LCSCs from common HCC cell lines using FACScan and microbeads showed no consistent marker expression pattern. We also show that LCSCs have unique subtypes. Immunohistochemistry of HCC tissues showed that different HCCs express unique combinations of LCSC markers. Quantitative real-time polymerase chain reaction analysis showed that LCSCs isolated using different markers in the same HCC phenotype had different expression profiles. Likewise, LCSCs isolated from different HCC phenotypes with the same marker also had unique expression profiles and displayed varying resistance profiles to Sorafenib. Thus, using a range of commonly used CSC markers in HCCs and cell lines, we demonstrate that currently available markers are not specific for LCSCs. LCSCs have unique subtypes that express distinctive combinations of LCSC markers and altered drug resistance profiles, making their identification problematic.

Possible regulatory role of Snail in NF-κB-mediated changes in E-cadherin in gastric cancer.

In the present study, we aimed to investigate the involvement of Snail in NF-κB-mediated changes of E-cadherin in gastric cancer. A total of 189 human gastric cancer tissues, and 32 normal gastric mucosal tissues were used to determine the expression levels of NF-κB, E-cadherin and Snail by immunohistochemistry. The correlation between the expression levels and patient clinicopathological data was analyzed. Human gastric cancer cell line SGC7901 was treated with the NF-κB inhibitor PDTC, and the expression levels of E-cadherin and Snail were investigated by qPCR and western blot. NF-κB, E-cadherin and Snail were all detected in normal gastric mucosa and cancer tissues of various differentiation statuses. However, the expression patterns of each protein were different. Strong expression of E-cadherin was detected in normal gastric mucosa, whereas its expression gradually declined in gastric cancer tissues, with weak expression observed in poorly differentiated gastric cancer tissues. In contrast, weak NF-κB and Snail expressions were present in normal gastric mucosa, while their expression levels gradually increased in gastric cancer tissues, with the strongest expression detected in poorly differentiated gastric cancers. The expression of E-cadherin was inversely correlated with that of Snail and NF-κB in the tissues tested. Blockade of NF-κB using its inhibitor PDTC led to a time-dependent reduction in Snail but a time-dependent increase in E-cadherin in SGC7901 cells. These results suggest that in human gastric cancer, loss of E-cadherin may be mediated through NF-κB-induced Snail upregulation. Further studies may reveal whether targeting the NF-κB-Snail-E-cadherin axis could be a useful approach for combating gastric cancer.

Dose perturbation induced by radiographic contrast inside brachytherapy balloon applicators.

Phantom measurements and Monte Carlo calculations have been performed for the purpose of characterizing the dose perturbation caused by radiographic contrast inside the MammoSite breast brachytherapy applicator. Specifically, the dose perturbation is quantified as a heterogeneity correction factor (HCF) for various balloon radii and contrast concentration levels. The dose perturbation is larger for larger balloon radii and higher contrast concentrations. Based on a validated Monte Carlo simulation, the calculated HCF values are 0.99 for a 2 cm radius balloon and 0.98 for a 3 cm radius balloon at 6% contrast concentration levels, and 0.89 and 0.87 for 2 and 3 cm radius balloons, respectively, at 100% contrast concentrations. For a typical implanted balloon radius of 2.4 cm, the HCF values decrease from 0.99 at 6% contrast concentration to 0.90 at 100% contrast concentration. For balloons implanted in patients at our institution, the mean HCF is 0.99, corresponding to a dose reduction of approximately 1%. The contrast effect results in a systematic reduction in the delivered dose, therefore the minimal amount of radiographic contrast necessary should be used.