Tying the knot between cytokine and toll-like receptor signaling in gastrointestinal tract cancers

Modified Banxiaxiexin decoction benefitted chemotherapy in treating gastric cancer by regulating multiple targets and pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Chemotherapy tolerance weakened efficacy of chemotherapy drugs in the treating gastric cancer (GC). Banxiaxiexin decoction (BXXXD) was widely used in digestive diseases for thousands of years in Traditional Chinese medicine (TCM). In order to better treat GC, three other herbs were added to BXXXD to create a new prescription named Modified Banxiaxiexin decoction (MBXXXD). Although MBXXXD potentially treated GC by improving chemotherapy tolerance, the possible mechanisms were still unknown.

AIM OF THE STUDY

To explore the therapeutic effect of MBXXXD on GC patients and explore the possible anti-cancer mechanism.

MATERIALS AND METHODS

A randomized controlled trial (n = 146) was conducted to evaluate the clinical efficacy between MBXXXD + chemotherapy (n = 73) and placebo + chemotherapy (n = 73) in GC patients by testing overall survival, progression free survival, clinical symptoms, quality of life score, tumor markers, T cell subpopulation, and adverse reactions. Network pharmacology was conducted to discover the potential mechanism of MBXXXD in treating GC. Metabolic activity assay, cell clone colony formation and mitochondrial apoptosis were detected in human GC cell lines including AGS cell, KNM-45 cell and SGC7901 cell treated by MBXXXD. Multiple pathways including P53, AKT, IκB, P65, P38, ERK, JNK p-AKT, p-P65, p-P38, p-ERK and p-JNK in AGS cell, KNM-45 cell and SGC7901 cell treated by MBXXXD and GC patients treated by MBXXXD + chemotherapy were also detected.

RESULTS

MBXXXD + chemotherapy promoted overall survival and progression free survival, improved clinical symptoms and quality of life score, increased T4 lymphocyte ratio and T8 lymphocyte ratio as well as T4/T8 lymphocyte ratio, and alleviated adverse reactions in GC patients. Network pharmacology predicted multiple targets and pathways of MBXXXD in treating GC including apoptosis, P53 pathway, AKT pathway, MAPK pathway. MBXXXD inhibited cell viability, decreased cell clone colony formation, and promoted mitochondrial apoptosis by producing reactive oxygen species (ROS), promoting mitochondrial permeability transition pore (MPTP) and the cleavage of pro-caspase-3 and pro-caspase-9, and decreasing mito-tracker red Chloromethyl-X-rosamine (CMXRos) in AGS cell, KNM-45 cell and SGC7901 cell. MBXXXD up-regulated the expression of P53 and IκB, and down-regulated the expression of p-AKT, p-P65, p-P38, p-ERK, p-JNK, AKT, P65, P38, ERK and JNK AGS cell, KNM-45 cell and SGC7901 cell treated by MBXXXD and GC patients treated by MBXXXD + chemotherapy.

CONCLUSION

MBXXXD benefitted chemotherapy for GC by regulating multiple targets and pathways.

Weipiling decoction alleviates N-methyl-N-nitro-N′-nitrosoguanidine-induced gastric precancerous lesions via NF-κB signalling pathway inhibition

Aim of the study

We aimed to explore how weipiling (WPL) decoction WPL alleviates gastric precancerous lesions (GPLs) and uncover its anti-inflammatory roles in GPL treatment.

Materials and methods

The anti-GPL action mechanisms of WPL were analysed using a network pharmacological method. The WPL extract was prepared in a traditional way and evaluated for its major components using high-performance liquid chromatography with tandem mass spectrometry (HPLC–MS/MS). BALB/c mice were exposed to N-methyl-N-nitro-N-nitrosoguanidine (MNNG) (150 μg/mL) for 6 weeks to induce GPLs. GPL mice were administered WPL (3.75 g/kg/day and 15 g/kg/day) for an additional 8 weeks. Haematoxylin and eosin (H&E) staining was used to investigate histological alterations in gastric tissues. Expression of the T helper 1 (Th1) cell markers CD4⁺ and interferon-gamma (INF-γ) were tested using immunohistochemistry (IHC). Inflammatory protein and mRNA levels in the nuclear factor kappa B (NF-κB) pathway were detected using western blotting and a quantitative reverse transcription polymerase chain reaction (RT-qPCR), respectively.

Results

We identified and selected 110 active compounds and 146 targets from public databases and references. Four representative components of WPL were established and quantified by HPLC–MS/MS analysis. WPL attenuated MNNG-induced GPLs, including epithelial shedding, cavity fusion, basement membranes with asymmetrical thickness, intestinal metaplasia, dysplasia, pro-inflammatory Th1-cell infiltration, and INF-γ production, indicating that WPL prevents inflammation in the gastric mucosa. Furthermore, WPL reversed MNNG-induced activation of the IκB/NF-κB signalling pathway and subsequently attenuated the upregulation of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase (NOX)) family members NOX2 and NOX4.

Conclusion

WPL attenuated GPLs by controlling the generation of pro-inflammatory elements and inhibiting the NF-κB signalling pathway in vivo.

TLR2 activation promotes tumour growth and associates with patient survival and chemotherapy response in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) has an extremely poor prognosis, and is plagued by a paucity of targeted treatment options and tumour resistance to chemotherapeutics. The causal link between chronic inflammation and PDAC suggests that molecular regulators of the immune system promote disease pathogenesis and/or therapeutic resistance, yet their identity is unclear. Here, we couple endoscopic ultrasound-guided fine-needle aspiration, which captures tumour biopsies from all stages, with whole transcriptome profiling of PDAC patient primary tumours to reveal enrichment of the innate immune Toll-like receptor 2 (TLR2) molecular pathway. Augmented TLR2 expression associated with a 4-gene "TLR2 activation" signature, and was prognostic for survival and predictive for gemcitabine-based chemoresistance. Furthermore, antibody-mediated anti-TLR2 therapy suppressed the growth of human PDAC tumour xenografts, independent of a functional immune system. Our results support TLR2-based therapeutic targeting for precision medicine in PDAC, with further clinical utility that TLR2 activation is prognostic and predictive for chemoresponsiveness.

MLH1 Deficiency Down-Regulates TLR4 Expression in Sporadic Colorectal Cancer

Patients with mismatch repair (MMR)-deficient colorectal cancer (CRC) have a more favorable prognosis than patients with tumors with intact MMR. In order to obtain further insights on the reasons for this different outcome, we investigated the interplay between MMR genes and TLR4/MyD88 signaling. The cancer genome atlas (TCGA) databases were selected to predict the differential expression of TLR4 in colon cancer and its correlation with MMR genes. Moreover, the expression of MMR genes and TLR4 was evaluated by immunohistochemistry in 113 CRC samples and a cohort of 63 patients was used to assess TLR4 mRNA expression and MLH1 epigenetic silencing status. In vitro, the effect of MLH1 knockdown on TLR4 expression was quantified by Real Time PCR. TLR4 expression resulted dependent on MMR status and directly correlated to MLH1 expression. In vitro, MLH1 silencing decreased TLR4 expression. These observations may reflect the better prognosis and the chemoresistance of patients with CRC and MMR defects.

SOCS3 protects against neonatal necrotizing enterocolitis via suppressing NLRP3 and AIM2 inflammasome activation and p65 nuclear translocation

BACKGROUND

Necrotizing enterocolitis (NEC) is an acquired disorder of mucosal damage characterized by the diffuse or local necrosis of the intestine. The suppressor of cytokine signaling 3 (SOCS3) has been demonstrated to possess anti-inflammatory action in gastritis, ulcerative colitis and other inflammatory diseases. The present study aims to explore the effects of SOCS3 on LPS-induced colonic cell model of NEC, and investigate the underlying mechanisms.

METHODS

Expression of SOCS3 in tissue samples of NEC and LPS-induced enterocytes were evaluated by real-time quantitative PCR (RT-qPCR). Western blotting and enzyme-linked immunosorbent assay (ELISA) were applied to examine the effect of SOCS3 on inflammatory molecules. Co-immunoprecipitation assay were devoted to explore the relation between SOCS3 and TLR4.

RESULTS

We proved that SOCS3 was expressed at a low level in tissue samples of NEC and LPS-induced enterocytes, and LPS inhibited SOCS3 expression via JAK2/STAT3 pathway. Overexpression of SOCS3 weaken the LPS-induced inflammatory response in FHC and CACO2 cells. Moreover, SOCS3 downregulates proinflammatory cytokines by targeting TLR4, thus mediating the p65 nuclear translocation, and the activation of NLR family pyrin domain containing 3/absent in melanoma-2 (NLRP3/AIM2) inflammasome, ultimately reveals its anti-inflammatory effects.

CONCLUSIONS

Taken together, our data revealed that LPS inhibited SOCS3 expression via JAK2/STAT3 pathway, and SOCS3 protects enterocytes against NEC through mediating p65 nuclear translocation and NLRP3/AIM2 inflammasome activation in a TLR4 dependent manner.

Multiple cytokine profiling in serum for early detection of gastric cancer

AIM

To investigate the value of multiparameter joint analysis in the early diagnosis of gastric cancer (GC) in clinical practice.

METHODS

Concentrations of CEA, CA724 and three kinds of cytokines (TNF-α, IL-6 and IL-8) in 176 GC patients, 117 atypical hyperplasia patients, and 204 healthy control individuals were used for building the diagnostic model, then 58 GC patients, 41 atypical hyperplasia patients, and 66 healthy control individuals were enrolled independently. The joints of the indicators were analyzed by binary logistic regression analysis method.

RESULTS

For discriminating the healthy control group and the GC group, IL-6 had the best diagnostic value, and the area under curve (AUC) of joint analysis was 0.95 (0.93-0.97). For the early stage and advanced stage GC, the AUC were 0.95 (0.92-0.98) and 0.95 (0.92-0.97). For discriminating the atypical hyperplasia group and GC group, CA724 had the best diagnostic value, and the AUC of joint analysis was 0.97 (0.95-0.99). For the early stage and advanced stage GC groups, the AUC were 0.98 (0.96-0.99) and 0.96 (0.94-0.98). After evaluation, for discriminating the GC, early stage GC and advanced cancer group from the healthy control group, the diagnostic sensitivity was 89.66%, 84.21% and 92.31%, respectively, and the specificity was 92.42%, 90.91% and 90.91%. For discriminating the GC, early stage GC and advanced cancer groups from the atypical hyperplasia group, the diagnostic sensitivity was 87.93%, 78.95% and 92.31%, respectively, and the specificity was 87.80%, 85.37% and 90.24%.

CONCLUSION

We have built a diagnostic model including CEA, CA724, IL-6, IL-8, and TNF-α. It may provide potential assistance as a screening method for the early detection of GC.

Forkhead box-P3+ regulatory T cells and toll-like receptor 2 co-expression in oral squamous cell carcinoma

BACKGROUND

The function of forkhead box-P3 (FoxP3) regulatory T cells (Treg) and toll-like receptor (TLR)2 protein in the oral cancer microenvironment is not fully understood, but evidence from other malignancies suggests it is likely they are involved with tumour development and progression. The aim of this study was to investigate the distribution of FoxP3⁺cells, TLR2⁺ cells and double-labelled FoxP3⁺TLR2⁺ immune cells in oral squamous cell carcinoma (OSCC), using immunohistochemistry (IHC) and immunofluorescence (IF).

METHODS

25 archival cases of OSCC were immunostained with anti-FoxP3 and anti-TLR2 antibodies. Inflamed hyperplastic oral mucosal tissues were used as controls. The proportion of single-labelled, double-labelled and negative cells was determined.

RESULTS

A higher frequency of double-labelled FoxP3⁺TLR2⁺ Tregs was observed within the immune cells of OSCC compared to inflamed controls using IHC (p<0.05). Cell-to-cell contact between single-stained TLR2⁺ cells and FoxP3⁺ cells was noted. Double IF studies validated demonstration of co-expression of FoxP3⁺/TLR2⁺ immune cells in OSCC.

CONCLUSION

The presence of FoxP3⁺TLR2⁺ cells within the OSCC microenvironment may represent a dendritic cell-dependent pathway capable of inhibiting Treg suppressive activity, potentially enhancing the anti-tumour response. Modulation of TLR2-Treg interactions should be further explored to determine if they have a role in the therapeutic management of OSCC.

NF-κB Signaling in Gastric Cancer

Gastric cancer is a leading cause of cancer death worldwide. Diet, obesity, smoking and chronic infections, especially with Helicobacter pylori, contribute to stomach cancer development. H. pylori possesses a variety of virulence factors including encoded factors from the cytotoxin-associated gene pathogenicity island (cagPAI) or vacuolating cytotoxin A (VacA). Most of the cagPAI-encoded products form a type 4 secretion system (T4SS), a pilus-like macromolecular transporter, which translocates CagA into the cytoplasm of the host cell. Only H. pylori strains carrying the cagPAI induce the transcription factor NF-κB, but CagA and VacA are dispensable for direct NF-κB activation. NF-κB-driven gene products include cytokines/chemokines, growth factors, anti-apoptotic factors, angiogenesis regulators and metalloproteinases. Many of the genes transcribed by NF-κB promote gastric carcinogenesis. Since it has been shown that chemotherapy-caused cellular stress could elicit activation of the survival factor NF-κB, which leads to acquisition of chemoresistance, the NF-κB system is recommended for therapeutic targeting. Research is motivated for further search of predisposing conditions, diagnostic markers and efficient drugs to improve significantly the overall survival of patients. In this review, we provide an overview about mechanisms and consequences of NF-κB activation in gastric mucosa in order to understand the role of NF-κB in gastric carcinogenesis.

Vam3, a Compound Derived from Vitis amurensis Rupr., Attenuated Colitis-Related Tumorigenesis by Inhibiting NF-κB Signaling Pathway

Background: Chronic inflammation is one of the important mediators of colitis-related colon cancer (CRC). Abundant mast cells (MCs) were observed in the tumor microenvironment and mediators released upon MC activation play an important role in the process of chronic inflammation. Previously, we found that activation of intestine mucosal MCs recruited and modulated the inflammatory CD11b⁺Gr1⁺ cells to promote the CRC development. In the current study we investigated the effects of Vam3, a resveratrol dimer with potent anti-inflammatory effects, on CRC development.

Methods: RBL-2H3 cells, a basophilic leukemia cell line, were pretreated with 2.5 or 5 µM Vam3 and then stimulated with dinitrophenol-conjugated bovine serum albumin (DNP-BSA) plus lipopolysaccharide (LPS). The MC degranulation was determined by measuring β-hexosaminidase release. Generation of TNF-α and IL-6 in RBL-2H3 cells or in peritoneal macrophages was determined by ELISA and real-time qPCR. NF-κB p65 and phospho-NF-κB p65 expression was determined by Western blotting. NF-κB activity in RAW264.7 cells was determined by luciferase reporter assay. CRC was induced in C57BL/6 mice by intraperitoneal injection of azoxymethane (AOM), followed by oral exposure to dextran sodium sulfate (DSS). Vam3 at 50 mg/kg, or disodium cromoglycate (DSCG, MC stabilizer) at 100 mg/kg, or vehicle were administrated to the mice 4 weeks after DSS withdrawal. Levels of TNF-α, IL-6, and mouse MC protease-1 were determined by ELISA. Infiltration of CD11b⁺Gr1⁺ cells was determined by flow cytometry analysis. One-way ANOVA was used to compare difference between groups.

Results: Pretreatment with Vam3 significantly inhibited RBL-2H3 cell degranulation and inflammatory cytokine production from RBL-2H3 cells and from peritoneal macrophages. After Vam3 treatment, NF-κB activity in RAW264.7 cells, and expressions of phospho-NF-κB p65 in RBL-2H3 cells and in peritoneal macrophages were significantly down-regulated. In the AOM plus DSS-induced CRC murine model, the Vam3 and DSCG-treated mice had less tumor numbers than those treated with vehicle. Expression of phospho-NF-κB p65, production of inflammatory cytokines, and infiltration of MCs and CD11b⁺Gr1⁺ cells were attenuated in the Vam3-treated mice.

Conclusion: Vam3 treatment could attenuate the CRC development. This effect may be due to its inhibition on NF-κB signaling pathway in MCs and macrophages of the inflamed intestines.

STAT3-mediated TLR2/4 pathway upregulation in an IFN-gamma-induced Chlamydia trachomatis persistent infection model

Inflammatory pathological injury caused by Chlamydia trachomatis persistent infection could lead to a variety of urogenital tract diseases. By comparing the cytokine production and PRR (pattern recognition receptor) expression between cell models with acute or persistent C. trachomatis infection, our data supported that persistent infection of C. trachomatis led to abnormal activation of toll-like receptor (TLR)2/4 signaling pathway and elevated IL-1α and IL-6 production, which was mediated by signal transducer and activator of transcription3 (STAT3). Studying the effects of abnormal activation of TLR signaling pathway in the cells with C. trachomatis persistent infection could provide new hints for chronic infection treatment and an important experimental basis for understanding the pathogenesis of C. trachomatis persistent infection.

Quercetin Suppresses the Migration and Invasion in Human Colon Cancer Caco-2 Cells Through Regulating Toll-like Receptor 4/Nuclear Factor-kappa B Pathway

Objective:

The migration and invasion features, which were associated with inflammatory response, acted as vital roles in the development of colon cancer. Quercetin, a bioflavonoid compound, was widely spread in vegetables and fruits. Although quercetin exerts antioxidant and anticancer activities, the molecular signaling pathways in human colon cancer cells remain unclear. Hence, the present study was conducted to investigate the suppression of quercetin on migratory and invasive activity of colon cancer and the underlying mechanism.

Materials and Methods:

The effect of quercetin on cell viability, migration, and invasion of Caco-2 cells was analyzed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, wound-healing assay, and transwell chambers assay, respectively. The protein expressions of toll-like receptor 4 (TLR4), nuclear factor-kappa B (NF-κB) p65, mitochondrial membrane potential-2 (MMP-2), and MMP-9 were detected by Western blot assay. The inflammatory factors, such as tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (Cox-2), and interleukin-6 (IL-6), in cell supernatant were detected by enzyme-linked immunosorbent assay.

Results:

The concentration of quercetin <20 μM was chosen for further experiments. Quercetin (5 μM) could remarkably suppress the migratory and invasive capacity of Caco-2 cells. The expressions of metastasis-related proteins of MMP-2, MMP-9 were decreased, whereas the expression of E-cadherin protein was increased by quercetin in a dose-dependent manner. Interestingly, the anti-TLR4 (2 μg) antibody or pyrrolidine dithiocarbamate (PDTC; 1 μM) could affect the inhibition of quercetin on cell migration and invasion, as well as the protein expressions of MMP-2, MMP-9, E-cadherin, TLR4, and NF-κB p65. In addition, quercetin could reduce the inflammation factors production of TNF-α, Cox-2, and IL-6.

Conclusion:

The findings suggested for the 1^st time that quercetin might exert its anticolon cancer activity via the TLR4- and/or NF-κB-mediated signaling pathway.

SUMMARY

Quercetin could remarkably suppress the migratory and invasive capacity of Caco-2 cells

The expressions of metastasis-related proteins of mitochondrial membrane potential-2 (MMP-2), MMP-9 were decreased, whereas the expression of E-cadherin protein was increased by quercetin in a dose-dependent manner

The anti-toll-like receptor 4 (TLR4) antibody or pyrrolidine dithiocarbamate affected the inhibition of quercetin on cell migration and invasion, as well as the protein expressions of MMP-2, MMP-9, E-cadherin, TLR4, and nuclear factor-kappa B p65

Quercetin could reduce the inflammation factors production of tumor necrosis factors-α, cyclooxygenase-2, and interleukin-6.

Abbreviations used: MTT: 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphen yltetrazolium bromide, TLR4: Toll-like receptor 4, NF-κB: Nuclear factor-kappa B, MMP-2: Mitochondrial membrane potential-2, MMP-9: Mitochondrial membrane potential-9, TNF-α: Tumor necrosis factor-α, Cox-2: Cyclooxygenase-2, IL-6: Interleukin-6, ELISA: Enzyme-linked immunosorbent assay, PDTC: Pyrrolidine dithiocarbamate, ROS: Reactive oxygen species, DMSO: Dimethyl sulfoxide, FBS: Fetal bovine serum, DMEM: Dulbecco modified Eagle medium, OD: Optical density, IPP: Image Pro-plus, PBS: Phosphate buffered saline, SD: Standard deviation, ANOVA: One-way analysis of variance, SPSS: Statistical Package for the Social Sciences, ECM: Extracellular matrix, TLRs: Toll-like receptors, LPS: Lipopolysaccharide.

NOD-Like Receptor Protein 3 Inflammasome Priming and Activation in Barrett's Epithelial Cells

BACKGROUND & AIMS

Microbial molecular products incite intestinal inflammation by activating Toll-like receptors (TLRs) and inflammasomes of the innate immune system. This system's contribution to esophageal inflammation is not known. Gram-negative bacteria, which dominate the esophageal microbiome in reflux esophagitis, produce lipopolysaccharide (LPS), a TLR4 ligand. TLR4 signaling produces pro-interleukin (IL)1β, pro-IL18, and NOD-like receptor protein 3 (NLRP3), which prime the NLRP3 inflammasome. Subsequent NLRP3 inflammasome activation cleaves caspase-1, inducing secretion of proinflammatory cytokines and pyroptosis (inflammatory cell death). We explored LPS effects on NLRP3 inflammasome priming and activation in esophageal cells.

METHODS

We exposed esophageal squamous and Barrett's epithelial cells to LPS and measured the following: (1) TLR4, pro-IL1β, pro-IL18, and NLRP3 expression; (2) caspase-1 activity; (3) tumor necrosis factor-α, IL8, IL1β, and IL18 secretion; (4) lactate dehydrogenase (LDH) release (a pyroptosis marker); and (5) mitochondrial reactive oxygen species (ROS). As inhibitors, we used acetyl-Tyr-Val-Ala-Asp-CHO for caspase-1, small interfering RNA for NLRP3, and (2-(2,2,6,6,-Tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl)triphenylphosphonium chloride for mitochondrial ROS.

RESULTS

Squamous and Barrett's cells expressed similar levels of TLR4, but LPS induced TLR4 signaling that increased tumor necrosis factor-α and IL8 secretion only in Barrett's cells. Barrett's cells treated with LPS showed increased expression of pro-IL18, pro-IL1β, and NLRP3, and increased mitochondrial ROS levels, caspase-1 activity, IL1β and IL18 secretion, and LDH release. Acetyl-Tyr-Val-Ala-Asp-CHO, NLRP3 small interfering RNA, and Mito-TEMPO all blocked LPS-induced IL1β and IL18 secretion and LDH release.

CONCLUSIONS

In Barrett's cells, LPS both primes and activates the NLRP3 inflammasome, causing secretion of proinflammatory cytokines and pyroptosis. By triggering molecular events promoting inflammation, the esophageal microbiome might contribute to inflammation-mediated carcinogenesis in Barrett's esophagus.

New and Unexpected Biological Functions for the Src-Homology 2 Domain-Containing Phosphatase SHP-2 in the Gastrointestinal Tract

SHP-2 is a tyrosine phosphatase expressed in most embryonic and adult tissues. SHP-2 regulates many cellular functions including growth, differentiation, migration, and survival. Genetic and biochemical evidence show that SHP-2 is required for rat sarcoma viral oncogene/extracellular signal-regulated kinases mitogen-activated protein kinase pathway activation by most tyrosine kinase receptors, as well as by G-protein-coupled and cytokine receptors. In addition, SHP-2 can regulate the Janus kinase/signal transducers and activators of transcription, nuclear factor-κB, phosphatidyl-inositol 3-kinase/Akt, RhoA, Hippo, and Wnt/β-catenin signaling pathways. Emerging evidence has shown that SHP-2 dysfunction represents a key factor in the pathogenesis of gastrointestinal diseases, in particular in chronic inflammation and cancer. Variations within the gene locus encoding SHP-2 have been associated with increased susceptibility to develop ulcerative colitis and gastric atrophy. Furthermore, mice with conditional deletion of SHP-2 in intestinal epithelial cells rapidly develop severe colitis. Similarly, hepatocyte-specific deletion of SHP-2 induces hepatic inflammation, resulting in regenerative hyperplasia and development of tumors in aged mice. However, the SHP-2 gene initially was suggested to be a proto-oncogene because activating mutations of this gene were found in pediatric leukemias and certain forms of liver and colon cancers. Moreover, SHP-2 expression is up-regulated in gastric and hepatocellular cancers. Notably, SHP-2 functions downstream of cytotoxin-associated antigen A (CagA), the major virulence factor of Helicobacter pylori, and is associated with increased risks of gastric cancer. Further compounding this complexity, most recent findings suggest that SHP-2 also coordinates carbohydrate, lipid, and bile acid synthesis in the liver and pancreas. This review aims to summarize current knowledge and recent data regarding the biological functions of SHP-2 in the gastrointestinal tract.

Helicobacter pylori-infected MSCs acquire a pro-inflammatory phenotype and induce human gastric cancer migration by promoting EMT in gastric cancer cells

Accumulating clinical and experimental evidence has suggested that Helicobacter pylori (H. pylori) infection-associated gastric cancer (GC) is associated with high rates of mortality and serious health effects. The majority of patients succumb to H. pylori infection-associated GC due to metastasis. Mesenchymal stem cells (MSCs), which have multipotent differentiation potential, may be recruited into the tumor-associated stroma. MSCs are crucial components of the H. pylori infection-associated GC microenvironment, and may be critical for GC cell migration. In this study, an MSCs/H. pylori co-culture model was designed, and the effect of H. pylori-infected MSCs on the migration of GC cells was evaluated using a Transwell migration assay. H. pylori-infected MSC cytokine expression was evaluated using Luminex/ELISA. The expression of epithelial-mesenchymal transition (EMT) markers in the GC cells treated with supernatants from H. pylori-infected MSCs were detected by western blot analysis. The results demonstrated that the interaction between MSCs and H. pylori may induce GC cell migration, through secretion of a combination of cytokines that promote EMT in GC cells. The expression of phosphorylated forms of nuclear factor-κB (NF-κB) was observed to be increased in MSCs by H. pylori. Inhibition of NF-κB activation by pyrrolidine dithiocarbamate blocked the effects of H. pylori-infected MSCs on SGC-7901 human stomach adenocarcinoma cell migration. Overall, the results of the present study suggest that H. pylori-infected MSCs acquire a pro-inflammatory phenotype through secretion of a combination of multiple cytokines, a number of which are NF-κB-dependent. These cytokines enhance H. pylori infection-associated GC cell migration by promoting EMT in GC cells. The results of the present study provide novel evidence for the modulatory effect of MSCs in the tumor microenvironment and provide insight into the significance of stromal cell involvement in GC progression.

Genetic association of NQO1 609C>T polymorphism with risk of gastrointestinal cancer: evidence from case-control studies

BACKGROUND

Numerous studies have evaluated the association between NQO1 609C>T polymorphism and gastrointestinal (GI) cancer. However, the results remain inconclusive. To obtain a more precise estimation of the relation, we conducted an analysis of all available case-control studies.

METHODS

Eligible studies were identified by searching the databases and finally 19 articles were included in the meta-analysis. Odds ratio (OR) with 95% confidence interval (95% CI) was applied to assess the association between NQO1 609C>T polymorphism and GI cancer risk. Z test was used to evaluate the significance of OR and 95% CI.

RESULTS

In the overall analysis, there existed a significant association between NQO1 609C>T polymorphism and GI cancer susceptibility (T vs. C: OR = 1.07, 95% CI = 1.01-1.14). The subgroup analysis based on ethnicity showed that NQO1 609C>T polymorphism was associated with susceptibility to GI cancer in mixed population (TT vs. CC: OR = 2.21, 95% CI = 1.44-3.40; TT vs. CT + CC: OR = 2.26, 95% CI = 1.48-3.44; Allele T vs. Allele C: OR = 1.24, 95% CI = 1.05-1.47). For the subgroup analysis according to source of control, a remark relationship of 609C>T with increased risk of GI cancer was observed in HB population (Allele T vs. Allele C: OR = 1.07, 95% CI = 1.01-1.14).

CONCLUSION

Our results demonstrated that NQO1 609C>T polymorphism might be associated with susceptibility to GI cancer.

Toll-like receptor signaling in colorectal cancer: Carcinogenesis to cancer therapy

Toll-like receptors (TLRs) are germ line encoded innate immune sensors that recognize conserved microbial structures and host alarmins, and signal expression of major histocompatibility complex proteins, costimulatory molecules, and inflammatory mediators by macrophages, neutrophils, dendritic cells, and other cell types. These protein receptors are characterized by their ability to respond to invading pathogens promptly by recognizing particular TLR ligands, including flagellin and lipopolysaccharide of bacteria, nucleic acids derived from viruses, and zymosan of fungi. There are 2 major TLR pathways; one is mediated by myeloid differentiation factor 88 (MYD88) adaptor proteins, and the other is independent of MYD88. The MYD88-dependent pathway involves early-phase activation of nuclear factor of kappa light polypeptide gene enhancer in B-cells 1 (NF-κB1) and all the TLRs, except TLR3, have been shown to activate this pathway. TLR3 and TLR4 act via MYD88-independent pathways with delayed activation of NF-κB signaling. TLRs play a vital role in activating immune responses. TLRs have been shown to mediate inflammatory responses and maintain epithelial barrier homeostasis, and are highly likely to be involved in the activation of a number of pathways following cancer therapy. Colorectal cancer (CRC) is one of the most common cancers, and accounts for almost half a million deaths annually worldwide. Inflammation is considered a risk factor for many common malignancies including cancers of the colorectum. The key molecules involved in inflammation-driven carcinogenesis include TLRs. As sensors of cell death and tissue remodeling, TLRs may have a universal role in cancer; stimulation of TLRs to activate the innate immune system has been a legitimate therapeutic strategy for some years. TLRs 3/4/7/8/9 are all validated targets for cancer therapy, and a number of companies are developing agonists and vaccine adjuvants. On the other hand, antagonists may favor inhibition of signaling responsible for autoimmune responses. In this paper, we review TLR signaling in CRC from carcinogenesis to cancer therapy.

Transcriptional regulation of pattern recognition receptors by Jak/STAT signaling, and the implications for disease pathogenesis

Cytokines are well known for their pleiotropism, affecting a large number of cellular responses, including proliferation, survival, functional maturation, and immunomodulation. It is, therefore, not surprising that both the deregulated expression of cytokines and the subsequent activation of their downstream signaling pathways is a common feature of many cancers, as well as chronic inflammatory, autoimmune, metabolic, and cardiovascular diseases. In this regard, activation of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway is the predominant intracellular signaling event triggered by cytokines, with STAT1 and STAT3 having the greatest diversity of biological functions among the 7 known members of the STAT family of latent transcription factors. Notably, over recent years, it has emerged that STAT1 and STAT3 are employed by various cytokines to manipulate the signal output of heterologous receptors of the innate immune system, namely pattern recognition receptors (PRRs), with both immune and nonimmune (eg, oncogenic, metabolic) cellular processes being affected. This review highlights these pivotal advancements in our understanding of how a cross talk between cytokine and PRR signaling networks can impact on a variety of cellular responses during disease pathogenesis, and the potential therapeutic implications of targeting these networks.

Novel role of toll-like receptors in Helicobacter pylori - induced gastric malignancy

Helicobacter pylori (H. pylori) infects the human stomach during infancy and develops into chronic active inflammation. The majority of H. pylori tend to colonize within the mucous gel layer of the stomach. The stomach lacks its own immune function, thus innate immunity as the first line of defense is vital for specific immunity against H. pylori. We review recent discoveries in the pathophysiologic roles of toll-like receptors (TLRs), mainly TLR2 and TLR4, in H. pylori-induced inflammation. In addition, the TLR pathways activated by H. pylori-induced inflammation have been shown to be closely associated not only with gastric carcinogenesis, but also with formation of the tumor microenvironment through the production of pro-inflammatory cytokines, chemokines, and reactive oxygen species. Although the correlation between single nucleotide polymorphisms of TLRs and gastric cancer risk remains unclear, a recent study demonstrated that STAT3-driven up-regulation of TLR2 might promote gastric tumorigenesis independent of inflammation. Further research on the regulation of TLRs in H. pylori-associated gastric carcinogenesis will uncover diagnostic/predictive biomarkers and therapeutic targets for gastric cancer.

Amphiregulin

Amphiregulin (AREG) is a ligand of the epidermal growth factor receptor (EGFR), a widely expressed transmembrane tyrosine kinase. AREG is synthesized as a membrane-anchored precursor protein that can engage in juxtacrine signaling on adjacent cells. Alternatively, after proteolytic processing by cell membrane proteases, mainly TACE/ADAM17, AREG is secreted and behaves as an autocrine or paracrine factor. AREG gene expression and release is induced by a plethora of stimuli including inflammatory lipids, cytokines, hormones, growth factors and xenobiotics. Through EGFR binding AREG activates major intracellular signaling cascades governing cell survival, proliferation and motility. Physiologically, AREG plays an important role in the development and maturation of mammary glands, bone tissue and oocytes. Chronic elevation of AREG expression is increasingly associated with different pathological conditions, mostly of inflammatory and/or neoplastic nature. Here we review the essential aspects of AREG structure, function and regulation, discuss the basis for its differential role within the EGFR family of ligands, and identify emerging aspects in AREG research with translational potential.

Inflammation and gastrointestinal cancer: an overview

Gastrointestinal cancers collectively rank as the most lethal cancers worldwide, and are strongly linked with chronic inflammation. Despite advances over the last decade into our understanding of the etiology of these malignancies, both from a host perspective and with respect to environmental factors, current treatment strategies comprising surgery, chemotherapy and/or radiotherapy are still associated with unacceptably poor patient survival rates. Accordingly, there is a pressing need to identify new molecular targets which can underpin the development of next-generation treatment strategies to improve patient outcomes, and serve as biomarkers for early disease detection. In this review we provide an updated discussion on the identity of such candidate molecules, with a focus on innate immune system regulators within the gastrointestinal mucosal epithelium which promote inflammation and tumorigenesis.