Stromal cell-derived factor-1 overexpression induces gastric dysplasia through expansion of stromal myofibroblasts and epithelial progenitors

The Fibroblast Landscape in Stomach Carcinogenesis

Numerous recent studies using single cell RNA sequencing and spatial transcriptomics have shown the vast cell heterogeneity, including epithelial, immune, and stromal cells, present in the normal human stomach and at different stages of gastric carcinogenesis. Fibroblasts within the metaplastic and dysplastic mucosal stroma represent key contributors to the carcinogenic microenvironment in the stomach. The heterogeneity of fibroblast populations is present in the normal stomach, but plasticity within these populations underlies their alterations in association with both metaplasia and dysplasia. In this review, we summarize and discuss efforts over the past several years to study the fibroblast components in human stomach from normal to metaplasia, dysplasia, and cancer. In the stomach, myofibroblast populations increase during late phase carcinogenesis and are a source of matrix proteins. PDGFRA-expressing telocyte-like cells are present in normal stomach and expand during metaplasia and dysplasia in close proximity with epithelial lineages, likely providing support for both normal and metaplastic progenitor niches. The alterations in fibroblast transcriptional signatures across the stomach carcinogenesis process indicate that fibroblast populations are likely as plastic as epithelial populations during the evolution of carcinogenesis.

The Importance of Th2 Immune Responses in Mediating the Progression of Gastritis-Associated Metaplasia to Gastric Cancer

Gastric cancer is one of the leading causes of cancer deaths worldwide, with chronic gastritis representing the main predisposing factor initiating the cascade of events leading to metaplasia and eventually progressing to cancer. A widely accepted classification distinguishes between autoimmune and environmental atrophic gastritis, mediated, respectively, by T cells promoting the destruction of the oxyntic mucosa, and chronic H. pylori infection, which has also been identified as the major risk factor for gastric cancer. The original dogma posits Th1 immunity as a main causal factor for developing gastritis and metaplasia. Recently, however, it has become evident that Th2 immune responses play a major role in the events causing chronic inflammation leading to tumorigenesis, and in this context, many different cell types and cytokines are involved. In particular, the activity of cytokines, such as IL-33 and IL-13, and cell types, such as mast cells, M2 macrophages and eosinophils, are intertwined in the process, promoting chronic gastritis-dependent and more diffuse metaplasia. Herein, we provide an overview of the critical events driving the pathology of this disease, focusing on the most recent findings regarding the importance of Th2 immunity in gastritis and gastric metaplasia.

Homeostasis and Cancer Initiation: Organoids as Models to Study the Initiation of Gastric Cancer

Gastric cancer represents a significant disease burden worldwide. The factors that initiate cancer are not well understood. Chronic inflammation such as that triggered by H. pylori infection is the most significant cause of gastric cancer. In recent years, organoid cultures developed from human and animal adult stem cells have facilitated great advances in our understanding of gastric homeostasis. Organoid models are now being exploited to investigate the role of host genetics and bacterial factors on proliferation and DNA damage in gastric stem cells. The impact of a chronic inflammatory state on gastric stem cells and the stroma has been less well addressed. This review discusses what we have learned from the use of organoid models to investigate cancer initiation, and highlights questions on the contribution of the microbiota, chronic inflammatory milieu, and stromal cells that can now be addressed by more complex coculture models.

Cancer Stem Cells and the Tumor Microenvironment in Gastric Cancer

Gastric cancer (GC) remains one of the leading causes of cancer-related death worldwide. Cancer stem cells (CSCs) might be responsible for tumor initiation, relapse, metastasis and treatment resistance of GC. The tumor microenvironment (TME) comprises tumor cells, immune cells, stromal cells and other extracellular components, which plays a pivotal role in tumor progression and therapy resistance. The properties of CSCs are regulated by cells and extracellular matrix components of the TME in some unique manners. This review will summarize current literature regarding the effects of CSCs and TME on the progression and therapy resistance of GC, while emphasizing the potential for developing successful anti-tumor therapy based on targeting the TME and CSCs.

Lung-Resident Mesenchymal Stem Cell Fates within Lung Cancer

Simple Summary

Lung cancer remains the leading cause of cancer-related deaths worldwide. Herein, the heterogeneous tumor stroma decisively impacts on tumor progression, therapy resistance, and, thus, poor clinical outcome. Among the numerous non-epithelial cells constructing the complex environment of lung carcinomas, mesenchymal stem cells (MSC) gained attraction being stromal precursor cells that could be recruited and ‘educated’ by lung cancer cells to adopt a tumor-associated MSC phenotype, serve as source for activated fibroblasts and presumably for vascular mural cells finally reinforcing tumor progression. Lung-resident MSCs should be considered as ‘local MSCs in stand by’ ready to be arranged within the cancer stroma.

Abstract

Lung-resident mesenchymal stem cells (LR-MSCs) are non-hematopoietic multipotent stromal cells that predominately reside adventitial within lung blood vessels. Based on their self-renewal and differentiation properties, LR-MSCs turned out to be important regulators of normal lung homeostasis. LR-MSCs exert beneficial effects mainly by local secretion of various growth factors and cytokines that in turn foster pulmonary regeneration including suppression of inflammation. At the same time, MSCs derived from various tissues of origins represent the first choice of cells for cell-based therapeutic applications in clinical medicine. Particularly for various acute as well as chronic lung diseases, the therapeutic applications of exogenous MSCs were shown to mediate beneficial effects, hereby improving lung function and survival. In contrast, endogenous MSCs of normal lungs seem not to be sufficient for lung tissue protection or repair following a pathological trigger; LR-MSCs could even contribute to initiation and/or progression of lung diseases, particularly lung cancer because of their inherent tropism to migrate towards primary tumors and metastatic sites. However, the role of endogenous LR-MSCs to be multipotent tumor-associated (stromal) precursors remains to be unraveled. Here, we summarize the recent knowledge how ‘cancer-educated’ LR-MSCs impact on lung cancer with a focus on mesenchymal stem cell fates.

Interplay between extracellular matrix components and cellular and molecular mechanisms in kidney fibrosis

Chronic kidney disease (CKD) is characterized by pathological accumulation of extracellular matrix (ECM) proteins in renal structures. Tubulointerstitial fibrosis is observed in glomerular diseases as well as in the regeneration failure of acute kidney injury (AKI). Therefore, finding antifibrotic therapies comprises an intensive research field in Nephrology. Nowadays, ECM is not only considered as a cellular scaffold, but also exerts important cellular functions. In this review, we describe the cellular and molecular mechanisms involved in kidney fibrosis, paying particular attention to ECM components, profibrotic factors and cell-matrix interactions. In response to kidney damage, activation of glomerular and/or tubular cells may induce aberrant phenotypes characterized by overproduction of proinflammatory and profibrotic factors, and thus contribute to CKD progression. Among ECM components, matricellular proteins can regulate cell-ECM interactions, as well as cellular phenotype changes. Regarding kidney fibrosis, one of the most studied matricellular proteins is cellular communication network-2 (CCN2), also called connective tissue growth factor (CTGF), currently considered as a fibrotic marker and a potential therapeutic target. Integrins connect the ECM proteins to the actin cytoskeleton and several downstream signaling pathways that enable cells to respond to external stimuli in a coordinated manner and maintain optimal tissue stiffness. In kidney fibrosis, there is an increase in ECM deposition, lower ECM degradation and ECM proteins cross-linking, leading to an alteration in the tissue mechanical properties and their responses to injurious stimuli. A better understanding of these complex cellular and molecular events could help us to improve the antifibrotic therapies for CKD.

Could gastrointestinal tumor-initiating cells originate from cell-cell fusion in vivo?

Tumor-initiating cells (TICs) or cancer stem cells are believed to be responsible for gastrointestinal tumor initiation, progression, metastasis, and drug resistance. It is hypothesized that gastrointestinal TICs (giTICs) might originate from cell-cell fusion. Here, we systemically evaluate the evidence that supports or opposes the hypothesis of giTIC generation from cell-cell fusion both in vitro and in vivo. We review giTICs that are capable of initiating tumors in vivo with 5000 or fewer in vivo fused cells. Under this restriction, there is currently little evidence demonstrating that giTICs originate from cell-cell fusion in vivo. However, there are many reports showing that tumor generation in vitro occurs with more than 5000 fused cells. In addition, the mechanisms of giTIC generation via cell-cell fusion are poorly understood, and thus, we propose its potential mechanisms of action. We suggest that future research should focus on giTIC origination from cell-cell fusion in vivo, isolation or enrichment of giTICs that have tumor-initiating capabilities with 5000 or less in vivo fused cells, and further clarification of the underlying mechanisms. Our review of the current advances in our understanding of giTIC origination from cell-cell fusion may have significant implications for the understanding of carcinogenesis and future cancer therapeutic strategies targeting giTICs.

Tumor microenvironment in gastric cancers

The tumor microenvironment favors the growth and expansion of cancer cells. Many cell types are involved in the tumor microenvironment such as inflammatory cells, fibroblasts, nerves, and vascular endothelial cells. These stromal cells contribute to tumor growth by releasing various molecules to either directly activate the growth signaling in cancer cells or remodel surrounding areas. This review introduces recent advances in findings on the interactions within the tumor microenvironment such as in cancer-associated fibroblasts (CAFs), immune cells, and endothelial cells, in particular those established in mouse gastric cancer models. In mice, myofibroblasts in the gastric stroma secrete R-spondin and support normal gastric stem cells. Most CAFs promote tumor growth in a paracrine manner, but CAF population appears to be heterogeneous in terms of their function and origin, and include both tumor-promoting and tumor-restraining populations. Among immune cell populations, tumor-associated macrophages, including M1 and M2 macrophages, and myeloid-derived suppressor cells (MDSCs), are reported to directly or indirectly promote gastric tumorigenesis by secreting soluble factors or modulating immune responses. Endothelial cells or blood vessels not only fuel tumors with nutrients, but also interact with cancer stem cells and immune cells by secreting chemokines or cytokines, and act as a cancer niche. Understanding these interactions within the tumor microenvironment would contribute to unraveling new therapeutic targets.

Fibroblast Reprogramming in Gastrointestinal Cancer

Gastrointestinal cancers are a significant cause of cancer mortality worldwide and have been strongly linked with chronic inflammation. Current therapies focus on epithelial/cancer cells; however, the importance of the tumor microenvironment in the development and treatment of the disease is also now well established. Cancer-associated fibroblasts (CAFs) are a major component of the tumor microenvironment, and are actively participating in tumor initiation, promotion and metastasis. They structurally and functionally affect cancer cell proliferation, tumor immunity, angiogenesis, extracellular matrix remodeling and metastasis through a variety of signaling pathways. CAFs originate predominantly from resident mesenchymal cells, which are activated and reprogrammed in response to cues from cancer cells. In recent years, chronic inflammation of the gastrointestinal tract has also proven an important driver of mesenchymal cell activation and subsequent CAF development, which in turn are capable of regulating the transition from acute to chronic inflammation and cancer. In this review, we will provide a concise overview of the mechanisms that drive fibroblast reprogramming in cancer and the recent advances on the downstream signaling pathways that regulate the functional properties of the activated mesenchyme. This new mechanistic insight could pave the way for new therapeutic strategies and better prognosis for cancer patients.

The CXCL12-CXCR4/CXCR7 axis as a mechanism of immune resistance in gastrointestinal malignancies

Single agent checkpoint inhibitor therapy has not been effective for most gastrointestinal solid tumors, but combination therapy with drugs targeting additional immunosuppressive pathways is being attempted. One such pathway, the CXCL12-CXCR4/CXCR7 chemokine axis, has attracted attention due to its effects on tumor cell survival and metastasis as well as immune cell migration. CXCL12 is a small protein that functions in normal hematopoietic stem cell homing in addition to repair of damaged tissue. Binding of CXCL12 to CXCR4 leads to activation of G protein signaling kinases such as P13K/mTOR and MEK/ERK while binding to CXCR7 leads to β-arrestin mediated signaling. While some gastric and colorectal carcinoma cells have been shown to make CXCL12, the primary source in pancreatic cancer and peritoneal metastases is cancer-associated fibroblasts. Binding of CXCL12 to CXCR4 and CXCR7 on tumor cells leads to anti-apoptotic signaling through Bcl-2 and survivin upregulation, as well as promotion of the epithelial-to-mesechymal transition through the Rho-ROCK pathway and alterations in cell adhesion molecules. High levels of CXCL12 seen in the bone marrow, liver, and spleen could partially explain why these are popular sites of metastases for many tumors. CXCL12 is a chemoattractant for lymphocytes at lower levels, but becomes chemorepellant at higher levels; it is unclear exactly what gradient exists in the tumor microenvironment and how this influences tumor-infiltrating lymphocytes. AMD3100 (Plerixafor or Mozobil) is a small molecule CXCR4 antagonist and is the most frequently used drug targeting the CXCL12-CXCR4/CXCR7 axis in clinical trials for gastrointestinal solid tumors currently. Other small molecules and monoclonal antibodies against CXCR4 are being trialed. Further understanding of the CXCL12- CXCR4/CXCR7 chemokine axis in the tumor microenvironment will allow more effective targeting of this pathway in combination immunotherapy.

Upexpression of BHLHE40 in gastric epithelial cells increases CXCL12 production through interaction with p-STAT3 in Helicobacter pylori-associated gastritis

BHLHE40, a member of the basic helix-loop-helix transcription factor family, has been reported to play an important role in inflammatory diseases. However, the regulation and function of BHLHE40 in Helicobacter pylori (H pylori)-associated gastritis is unknown. We observed that gastric BHLHE40 was significantly elevated in patients and mice with H pylori infection. Then, we demonstrate that H pylori-infected GECs express BHLHE40 via cagA-ERK pathway. BHLHE40 translocates to cell nucleus, and then binds to cagA protein-activated p-STAT3 (Tyr705). The complex increases chemotactic factor CXCL12 expression (production). Release of CXCL12 from GECs fosters CD4⁺ T cell infiltration in the gastric mucosa. Our results identify the cagA-BHLHE40-CXCL12 axis that contributes to inflammatory response in gastric mucosa during H pylori infection.

Lactate-mediated epigenetic reprogramming regulates formation of human pancreatic cancer-associated fibroblasts

Even though pancreatic ductal adenocarcinoma (PDAC) is associated with fibrotic stroma, the molecular pathways regulating the formation of cancer associated fibroblasts (CAFs) are not well elucidated. An epigenomic analysis of patient-derived and de-novo generated CAFs demonstrated widespread loss of cytosine methylation that was associated with overexpression of various inflammatory transcripts including CXCR4. Co-culture of neoplastic cells with CAFs led to increased invasiveness that was abrogated by inhibition of CXCR4. Metabolite tracing revealed that lactate produced by neoplastic cells leads to increased production of alpha-ketoglutarate (aKG) within mesenchymal stem cells (MSCs). In turn, aKG mediated activation of the demethylase TET enzyme led to decreased cytosine methylation and increased hydroxymethylation during de novo differentiation of MSCs to CAF. Co-injection of neoplastic cells with TET-deficient MSCs inhibited tumor growth in vivo. Thus, in PDAC, a tumor-mediated lactate flux is associated with widespread epigenomic reprogramming that is seen during CAF formation.

Antitumor Effects of Anti-Semaphorin 4D Antibody Unravel a Novel Proinvasive Mechanism of Vascular-Targeting Agents

One of the main consequences of inhibition of neovessel growth and vessel pruning produced by angiogenesis inhibitors is increased intratumor hypoxia. Growing evidence indicates that tumor cells escape from this hypoxic environment to better nourished locations, presenting hypoxia as a positive stimulus for invasion. In particular, anti-VEGF/R therapies produce hypoxia-induced invasion and metastasis in a spontaneous mouse model of pancreatic neuroendocrine cancer (PanNET), RIP1-Tag2. Here, a novel vascular-targeting agent targeting semaphorin 4D (Sema4D) demonstrated impaired tumor growth and extended survival in the RIP1-Tag2 model. Surprisingly, although there was no induction of intratumor hypoxia by anti-Sema4D therapy, the increase in local invasion and distant metastases was comparable with the one produced by VEGFR inhibition. Mechanistically, the antitumor effect was due to an alteration in vascular function by modification of pericyte coverage involving platelet-derived growth factor B. On the other hand, the aggressive phenotype involved a macrophage-derived Sema4D signaling engagement, which induced their recruitment to the tumor invasive fronts and secretion of stromal cell-derived factor 1 (SDF1) that triggered tumor cell invasive behavior via CXCR4. A comprehensive clinical validation of the targets in different stages of PanNETs demonstrated the implication of both Sema4D and CXCR4 in tumor progression. Taken together, we demonstrate beneficial antitumor and prosurvival effects of anti-Sema4D antibody but also unravel a novel mechanism of tumor aggressivity. This mechanism implicates recruitment of Sema4D-positive macrophages to invasive fronts and their secretion of proinvasive molecules that ultimately induce local tumor invasion and distant metastasis in PanNETs. SIGNIFICANCE: An anti-semaphorin-4D vascular targeting agent demonstrates antitumor and prosurvival effects but also unravels a novel promalignant effect involving macrophage-derived SDF1 that promotes tumor invasion and metastasis, both in animal models and patients.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/20/5328/F1.large.jpg.See related commentary by Tamagnone and Franzolin, p. 5146.

Mesenchymal Stem Cell Secretion of SDF-1α Modulates Endothelial Function in Dilated Cardiomyopathy

BACKGROUND

Endothelial dysfunction contributes to the pathophysiology of dilated cardiomyopathy (DCM). Allogeneic but not autologous mesenchymal stem cells (MSCs) improve endothelial function in DCM patients. We hypothesized that these effects are modulated by release of stromal derived factor-1α (SDF-1α).

METHODS

Plasma TNFα and endothelial progenitor cell-colony forming units (EPC-CFUs) were assessed at baseline and 3-months post-injection in a subset of POSEIDON-DCM patients that received autologous (n = 11) or allogeneic (n = 10) MSCs. SDF-1α secretion by MSCs, endothelial cell (EC) TNFα mRNA expression, and levels of reactive oxygen species (ROS) in response to SDF-1α were measured in vitro.

RESULTS

As previously shown, DCM patients (n = 21) had reduced EPC-CFUs at baseline (3 ± 3), which were restored to normal by allogeneic MSCs 3-months post-treatment (Δ10 ± 4). DCM patients had elevated baseline plasma TNFα (n = 15, 22 ± 9.4 pg/mL). Allogeneic MSCs (n = 8) decreased, and autologous MSCs (n = 7) increased, plasma TNFα (-7.1 ± 3.1 vs. 22.2 ± 17.1 pg/mL, respectively; P = 0.0005). In culture, autologous MSCs (n = 11) secreted higher levels of SDF-1α than allogeneic MSCs (n = 6) [76.0 (63.7, 100.9) vs. 22.8 (7.2, 43.5) pg/mL, P = 0.0002]. SDF-1α and plasma TNFα negatively correlated with EPC-CFUs in both treatment groups (R = -0.7, P = 0.0004). ECs treated with 20 ng SDF-1α expressed lower levels of TNFα mRNA than cells treated with 100 ng (0.7 ± 0.2 vs. 2.1 ± 0.3, P = 0.0008). SDF-1α at low but not high concentration inhibited the generation of ROS.

CONCLUSION

MSC secretion of SDF-1α inversely correlates with EPC-CFU production in DCM patients and therefore may be a modulator of MSC therapeutic effect in this clinical setting.

CLINICAL TRIAL REGISTRATION

https://clinicaltrials.gov/ct2/show/NCT01392625, identifier NCT01392625.

The important role played by chemokines influence the clinical outcome of Helicobacter pylori infection

The extended infection with Helicobacter pylori (H. pylori), one of the most frequent infectious agents in humans, may cause gastritis, peptic ulcers, gastric mucosa-associated lymphoid tissue (MALT) lymphoma, and gastric cancer. During H. pylori infection, different kinds of inflammatory cells such as dendritic cells, macrophages, neutrophils, mast cells, eosinophils, T cells and B cells are accumulated into the stomach. The interactions between chemokines and their respective receptors recruit particular types of the leukocytes that ultimately determine the nature of immune response and therefore, have a main influence on the consequence of infection. The suitable production of chemokines especially in the early stages of H. pylori infection shapes appropriate immune responses that contribute to the H. pylori elimination. The unbalanced expression of the chemokines can contribute in the induction of inappropriate responses that result in the tissue damage or malignancy. Thus, chemokines and their receptors may be promising potential targets for designing the therapeutic strategies against various types H. pylori-related gastrointestinal disorders. In this review, a comprehensive explanation regarding the roles played by chemokines in H. pylori-mediated peptic ulcer, gastritis and gastric malignancies was provided while presenting the potential utilization of these chemoattractants as therapeutic elements.

Reactive Oxygen Species Are Involved in the Development of Gastric Cancer and Gastric Cancer-Related Depression through ABL1-Mediated Inflammation Signaling Pathway

Background

The mechanisms of crosstalk between depression and gastric cancer (GC) remain ill defined. Given that reactive oxygen species (ROS) is involved in the pathophysiology of both GC and depression, we try to explore the activities of ROS in the development of GC and GC-related depression.

Methods

110 patients with newly diagnosed GC were recruited in our study. The clinical characteristics of these patients were recorded. Inflammation and oxidative stress markers were detected by ELISA. The depression status of patients with GC was assessed during follow-up. The association between ROS, ABL1, and inflammation factors was evaluated in H₂O₂-treated GC cell lines and The Cancer Genome Atlas (TCGA) database. The effect of ABL1 on inflammation was detected with Imatinib/Nilotinib-treated GC cell lines. A chronic mild stress- (CMS-) induced patient-derived xenograft (PDX) mice model was established to assess the crosstalk between depression and GC.

Results

Depression was correlated with poor prognosis of patients with GC. GC patients with depression were under a high level of oxidative status as well as dysregulated inflammation. In the CMS-induced GC PDX mice model, CMS could facilitate the development of GC. Additionally, tumor bearing could induce depressive-like behaviors of mice. With the treatment of ROS, the activities of ABL1 and inflammatory signaling were enhanced both in vitro and in vivo, and blocking the activities of ABL1 inhibited inflammatory signaling.

Conclusions

ROS-activated ABL1 mediates inflammation through regulating NF-κB1 and STAT3, which subsequently leads to the development of GC and GC-related depression.

Resolution of Gastric Cancer-Promoting Inflammation: A Novel Strategy for Anti-cancer Therapy

The connection between inflammation and cancer was initially recognized by Rudolf Virchow in the nineteenth century. During the last decades, a large body of evidence has provided support to his hypothesis, and now inflammation is recognized as one of the hallmarks of cancer, both in etiopathogenesis and ongoing tumor growth. Infection with the pathogen Helicobacter pylori is the primary causal factor in 90% of gastric cancer (GC) cases. As we increase our understanding of how chronic inflammation develops in the stomach and contributes to carcinogenesis, there is increasing interest in targeting cancer-promoting inflammation as a strategy to treat GC. Moreover, once cancer develops and anti-cancer immune responses are suppressed, there is evidence of a substantial shift in the microenvironment and new targets for immune therapy emerge. In this chapter, we provide insight into inflammation-related factors, including T lymphocytes, macrophages, pro-inflammatory chemokines, and cytokines, which promote H. pylori-associated GC initiation and growth. While intervening with chronic inflammation is not a new practice in rheumatology or gastroenterology, this approach has not been fully explored for its potential to prevent carcinogenesis or to contribute to the treatment of GC. This review highlights current and possible strategies for therapeutic intervention including (i) targeting pro-inflammatory mediators, (ii) targeting growth factors and pathways involved in angiogenesis in the gastric tumor microenvironment, and (iii) enhancing anti-tumor immunity. In addition, we highlight a significant number of clinical trials and discuss the importance of individual tumor characterization toward offering personalized immune-related therapy.

Molecular alterations of cancer cell and tumour microenvironment in metastatic gastric cancer

The term metastasis is widely used to describe the endpoint of the process by which tumour cells spread from the primary location to an anatomically distant site. Achieving successful dissemination is dependent not only on the molecular alterations of the cancer cells themselves, but also on the microenvironment through which they encounter. Here, we reviewed the molecular alterations of metastatic gastric cancer (GC) as it reflects a large proportion of GC patients currently seen in clinic. We hope that further exploration and understanding of the multistep metastatic cascade will yield novel therapeutic targets that will lead to better patient outcomes.

Activation of Signal Transduction and Activator of Transcription 3 Signaling Contributes to Helicobacter-Associated Gastric Epithelial Proliferation and Inflammation

Background/Aim

Although IL-6-mediated activation of the signal transduction and activator of transcription 3 (STAT3) axis is involved in inflammation and cancer, the role of STAT3 in Helicobacter-associated gastric inflammation and carcinogenesis is unclear. This study investigated the role of STAT3 in gastric inflammation and carcinogenesis and examined the molecular mechanism of Helicobacter-induced gastric phenotypes.

Methods

To evaluate the contribution of STAT3 to gastric inflammation and carcinogenesis, we used wild-type (WT) and gastric epithelial conditional Stat3-knockout (Stat3^Δgec) mice. Mice were infected with Helicobacter felis and euthanized at 18 months postinfection. Mouse gastric organoids were treated with recombinant IL-6 (rIL-6) or rIL-11 and a JAK inhibitor (JAKi) to assess the role of IL-6/STAT3 signaling in vitro.

Results

Inflammation and mucous metaplasia were more severe in WT mice than in Stat3^Δgec mice. The epithelial cell proliferation rate and STAT3 activation were increased in WT mice. Application of rIL-6 and rIL-11 induced expression of intestinal metaplasia-associated genes, such as Tff2; this induction was suppressed by JAKi administration.

Conclusions

Loss of STAT3 signaling in the gastric mucosa leads to decreased epithelial cell proliferation, atrophy, and metaplasia in the setting of Helicobacter infection. Therefore, activation of STAT3 signaling may play a key role in Helicobacter-associated gastric carcinogenesis.

CXCR4 Is a Potential Target for Diagnostic PET/CT Imaging in Barrett's Dysplasia and Esophageal Adenocarcinoma

Purpose: Barrett's esophagus represents an early stage in carcinogenesis leading to esophageal adenocarcinoma. Considerable evidence supports a major role for chronic inflammation and diverse chemokine pathways in the development of Barrett's esophagus and esophageal adenocarcinoma.Experimental Design: Here we utilized an IL1β transgenic mouse model of Barrett's esophagus and esophageal adenocarcinoma and human patient imaging to analyze the importance of CXCR4-expressing cells during esophageal carcinogenesis.Results: IL1β overexpression induces chronic esophageal inflammation and recapitulates the progression to Barrett's esophagus and esophageal adenocarcinoma. CXCR4 expression is increased in both epithelial and immune cells during disease progression in pL2-IL1β mice and also elevated in esophageal adenocarcinoma patient biopsy samples. Specific recruitment of CXCR4-positive (CXCR4⁺) immune cells correlated with dysplasia progression, suggesting that this immune population may be a key contributor to esophageal carcinogenesis. Similarly, with progression to dysplasia, there were increased numbers of CXCR4⁺ columnar epithelial cells at the squamocolumnar junction (SCJ). These findings were supported by stronger CXCR4-related signal intensity in ex vivo fluorescence imaging and autoradiography with advanced dysplasia. Pilot CXCR4-directed PET/CT imaging studies in patients with esophageal cancer demonstrate the potential utility of CXCR4 imaging for the diagnosis and staging of esophageal cancer.Conclusion: In conclusion, the recruitment of CXCR4⁺ immune cells and expansion of CXCR4⁺ epithelial cells in esophageal dysplasia and cancer highlight the potential of CXCR4 as a biomarker and molecular target for diagnostic imaging of the tumor microenvironment in esophageal adenocarcinoma. Clin Cancer Res; 24(5); 1048-61. ©2017 AACR.

CXCR4-expressing Mist1+ progenitors in the gastric antrum contribute to gastric cancer development

Mist1 was recently shown to identify a discrete population of stem cells within the isthmus of the oxyntic gland within the gastric corpus. Chief cells at the base of the gastric corpus also express Mist1. The relevance of Mist1 expression as a marker of specific cell populations within the antral glands of the distal stomach, however, is unknown. Using Mist1-CreERT mice, we revealed that Mist1⁺ antral cells, distinct from the Mist1⁺ population in the corpus, comprise long-lived progenitors that reside within the antral isthmus above Lgr5⁺ or CCK2R⁺ cells. Mist1⁺ antral progenitors can serve as an origin of antral tumors induced by loss of Apc or MNU treatment. Mist1⁺ antral progenitors, as well as other antral stem/progenitor population, express Cxcr4, and are located in close proximity to Cxcl12 (the Cxcr4 ligand)-expressing endothelium. During antral carcinogenesis, there is an expansion of Cxcr4⁺ epithelial cells as well as the Cxcl12⁺ perivascular niche. Deletion of Cxcl12 in endothelial cells or pharmacological blockade of Cxcr4 inhibits antral tumor growth. Cxcl12/Cxcr4 signaling may be a potential therapeutic target.

CD133 mediates the TGF-β1-induced activation of the PI3K/ERK/P70S6K signaling pathway in gastric cancer cells

Cluster of differentiation (CD)133 has been reported to be involved in the activation of the extracellular signal-regulated kinase (ERK) signaling pathway in different types of cancer cells. CD133 has been reported to be involved in the activation of the ERK signaling pathway in various cancer cells. Transforming growth factor (TGF)-β1 has also been reported to mediate the activation of the ERK signaling pathway. In addition, TGF-β1 has been previously shown to mediate the activation of the ERK signaling pathway. Hence, the present study investigated the function of CD133 in the TGF-β1-induced activation of the ERK/P70S6K signaling pathway in human gastric cancer (GC) cells. To this end, GC cell lines SGC7901 and MKN45 were treated with TGF-β1. The expression of CD133, phospho-ERK (p-ERK) and phospho-P70S6 kinase (p-P70S6K) was upregulated in the cells treated with TGF-β1, while the expression of ERK and P70S6K was not altered. To investigate whether CD133 is involved in the TGF-β1-induced activation of the ERK/P70S6K signaling pathway in GC cells, immunomagnetic cell sorting was employed to isolate CD133⁺ GC cells, and a CD133-expression construct or CD133-targeting small interfering ribonucleic acids were transfected into cells to modulate the expression of CD133. Subsequently, the expression of CD133, ERK, p-ERK, P70S6K, and p-P70S6K was analyzed by western blotting. The CD133⁺ cells displayed a high expression of p-ERK and p-P70S6K. Furthermore, SGC7901 GC cells were treated with U0126, an inhibitor of the ERK signaling pathway, to assess whether CD133 is upstream of ERK/P70S6K. The results showed that the expression of p-ERK and p-P70S6K was downregulated in the cells treated with U0126, while the expression of CD133 remained unaltered. The above preliminary results showed that CD133 likely mediates the TGF-β1-induced activation of the ERK/P70S6K signaling pathway in human GC cells. To further understand the mechanism of regulation of the ERK/P70S6K signaling pathway by CD133, the expression of CD133 was modulated by transfecting cells with CD133-expression constructs or CD133-targeting small interfering ribonucleic acids. Results indicated that overexpression and silencing of CD133 directly increased and decreased the expression of p-ERK and p-P70S6K, respectively. Therefore, we hypothesized that CD133 mediates the TGF-β1-induced activation of the PI3K/ERK/P70S6K signaling pathway in human GC cells.

Metaplasia in the Stomach-Precursor of Gastric Cancer?

Despite a significant decrease in the incidence of gastric cancer in Western countries over the past century, gastric cancer is still one of the leading causes of cancer-related deaths worldwide. Most human gastric cancers develop after long-term Helicobacter pylori infection via the Correa pathway: the progression is from gastritis, atrophy, intestinal metaplasia, dysplasia, to cancer. However, it remains unclear whether metaplasia is a direct precursor of gastric cancer or merely a marker of high cancer risk. Here, we review human studies on the relationship between metaplasia and cancer in the stomach, data from mouse models of metaplasia regarding the mechanism of metaplasia development, and the cellular responses induced by H. pylori infection.

Inhibition of CXCL12/CXCR4 axis as a potential targeted therapy of advanced gastric carcinoma

The whole outcome for patients with gastric carcinoma (GC) is very poor because most of them remain metastatic disease during survival even at diagnosis or after surgery. Despite many improvements in multiple strategies of chemotherapy, immunotherapy, and targeted therapy, exploration of novel alternative therapeutic targets is still warranted. Chemokine receptor 4 (CXCR4) and its chemokine ligand 12 (CXCL12) have been identified with significantly elevated levels in various malignancies including GC, which correlates with the survival, proliferation, angiogenesis, and metastasis of tumor cells. Increasing experimental evidence suggests an implication of inhibition of CXCL12/CXCR4 axis as a promising targeted therapy, although there are rare trials focused on the therapeutic efficacy of CXCR4 inhibitors in GC until recently. Therefore, it is reasonable to infer that specific antagonists or antibodies targeting CXCL12/CXCR4 axis alone or combined with chemotherapy will be effective and worthy of further translational studies as a potential treatment strategy in advanced GC.

A unified model of the hierarchical and stochastic theories of gastric cancer

Gastric cancer (GC) is a life-threatening disease worldwide. Despite remarkable advances in treatments for GC, it is still fatal to many patients due to cancer progression, recurrence and metastasis. Regarding the development of novel therapeutic techniques, many studies have focused on the biological mechanisms that initiate tumours and cause treatment resistance. Tumours have traditionally been considered to result from somatic mutations, either via clonal evolution or through a stochastic model. However, emerging evidence has characterised tumours using a hierarchical organisational structure, with cancer stem cells (CSCs) at the apex. Both stochastic and hierarchical models are reasonable systems that have been hypothesised to describe tumour heterogeneity. Although each model alone inadequately explains tumour diversity, the two models can be integrated to provide a more comprehensive explanation. In this review, we discuss existing evidence supporting a unified model of gastric CSCs, including the regulatory mechanisms of this unified model in addition to the current status of stemness-related targeted therapy in GC patients.

Mesenchymal Cells in Colon Cancer

Mesenchymal cells in the intestine comprise a variety of cell types of diverse origins, functions, and molecular markers. They provide mechanical and structural support and have important functions during intestinal organogenesis, morphogenesis, and homeostasis. Recent studies of the human transcriptome have revealed their importance in the development of colorectal cancer, and studies from animal models have provided evidence for their roles in the pathogenesis of colitis-associated cancer and sporadic colorectal cancer. Mesenchymal cells in tumors, called cancer-associated fibroblasts, arise via activation of resident mesenchymal cell populations and the recruitment of bone marrow-derived mesenchymal stem cells and fibrocytes. Cancer-associated fibroblasts have a variety of activities that promote colon tumor development and progression; these include regulation of intestinal inflammation, epithelial proliferation, stem cell maintenance, angiogenesis, extracellular matrix remodeling, and metastasis. We review the intestinal mesenchymal cell-specific pathways that regulate these processes, with a focus on their roles in mediating interactions between inflammation and carcinogenesis. We also discuss how increasing our understanding of intestinal mesenchymal cell biology and function could lead to new strategies to identify and treat colitis-associated cancers.

Murine Models of Gastric Corpus Preneoplasia

Intestinal-type gastric adenocarcinoma evolves in a field of pre-existing metaplasia. Over the past 20 years, a number of murine models have been developed to address aspects of the physiology and pathophysiology of metaplasia induction. Although none of these models has achieved true recapitulation of the induction of adenocarcinoma, they have led to important insights into the factors that influence the induction and progression of metaplasia. Here, we review the pathologic definitions relevant to alterations in gastric corpus lineages and classification of metaplasia by specific lineage markers. In addition, we review present murine models of the induction and progression of spasmolytic polypeptide (TFF2)-expressing metaplasia, the predominant metaplastic lineage observed in murine models. These models provide a basis for the development of a broader understanding of the physiological and pathophysiological roles of metaplasia in the stomach.

CXCL1-Chemokine (C-X-C Motif) Receptor 2 Signaling Stimulates the Recruitment of Bone Marrow-Derived Mesenchymal Cells into Diffuse-Type Gastric Cancer Stroma

Tumor stromal cells play a critical role in the progression of diffuse-type gastric cancer (DGC). The aim of this study was to clarify where tumor stromal cells originate from and which factor(s) recruits them into the tumor stroma. Immunodeficient mice with bone marrow transplantation from the cytomegalovirus enhancer/chicken β-actin promoter-enhanced green fluorescent protein mice were used for the in vivo experiments. An in vitro study analyzed the chemotaxis-stimulating factor from DGC cells using bone marrow-derived mesenchymal cells (BM-MCs). The influences of chemokine (C-X-C motif) receptor 2 (CXCR2) inhibitor on the migration of BM-MCs were examined both in vitro and in vivo. BM-MCs frequently migrated into stroma of DGC in vivo. The number of migrating BM-MCs was increased by conditioned medium from DGC cells. CXCL1 from DGC cells stimulated the chemoattractant ability of BM-MCs. Both anti-CXCL1 antibody and CXCR2 inhibitor decreased the migration of BM-MCs, stimulated by DGC cells. A CXCR2 inhibitor, SB225002, reduced the recruitment of BM-MCs into the tumor microenvironment in vivo, decreasing tumor size and lymph node metastasis, and prolonging the survival of gastric tumor-bearing mice. These findings suggested that most tumor stromal cells in DGC might originate from BM-MCs. CXCL1 from DGC cells stimulates the recruitment of BM-MCs into tumor stroma via CXCR2 signaling of BM-MCs. Inhibition of BM-MC recruitment via the CXCL1-CXCR2 axis appears a promising therapy for DGC.

The first European family with gastric adenocarcinoma and proximal polyposis of the stomach: case report and review of the literature

BACKGROUND AND AIMS

Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) has to date been recognized in only 8 families worldwide. Recently, different point mutations within the Ying Yang 1 (YY1) binding motif in promoter 1B of the APC gene were assigned as causal in 6 families with GAPPS.

METHODS

We diagnosed GAPPS across 3 generations in a Czech white family.

RESULTS

The proband's mother died of gastric cancer at 49 years of age. The proband died of gastric cancer at 56 years of age. All 3 of the proband's daughters inherited polyposis, involving exclusively the gastric fundus and body, with relative sparing of the lesser curve. The daughters have all been regularly surveyed endoscopically. Polyposis progressed rapidly with intestinal differentiated low-grade and high-grade dysplasia present on polypectomy specimens 5 years after the original diagnosis. On this basis, all 3 of the proband's daughters were scheduled for prophylactic total gastrectomy. Unfortunately, the middle daughter presented with generalized gastric adenocarcinoma and died at the age of 26 years. The other 2 daughters (aged 30 and 23 years) underwent total gastrectomy within 6 weeks of their sister's death; histology of surgical specimens showed gastric adenocarcinoma stage IA (pT1a, N0, M0) in both cases. Bi-directional Sanger sequencing of promoter 1B revealed a point mutation (c.-191 T>C) in all 3 daughters of the proband.

CONCLUSIONS

Atypical endoscopic progression of the fundic gland polyposis, with the presence of dysplasia on polypectomy specimens and genetic testing with recently discovered mutations in promoter 1B of the APC gene might help clinicians to decide whether prophylactic gastrectomy should be performed.

Oesophageal adenocarcinoma and gastric cancer: should we mind the gap?

Over recent decades we have witnessed a shift in the anatomical distribution of gastric cancer (GC), which increasingly originates from the proximal stomach near the junction with the oesophagus. In parallel, there has been a dramatic rise in the incidence of oesophageal adenocarcinoma (OAC) in the lower oesophagus, which is associated with antecedent Barrett oesophagus (BO). In this context, there has been uncertainty regarding the characterization of adenocarcinomas spanning the area from the lower oesophagus to the distal stomach. Most relevant to this discussion is the distinction, if any, between OAC and intestinal-type GC of the proximal stomach. It is therefore timely to review our current understanding of OAC and intestinal-type GC, integrating advances from cell-of-origin studies and comprehensive genomic alteration analyses, ultimately enabling better insight into the relationship between these two cancers.

Transcription factor RUNX2 up-regulates chemokine receptor CXCR4 to promote invasive and metastatic potentials of human gastric cancer

Runt-related transcription factor 2 (RUNX2) is a regulator of embryogenesis and development, but has also been implicated in the progression of certain human cancer. This study aimed to elucidate the role of RUNX2 in the invasive and metastatic potentials of human gastric cancer (GC) and the underlying mechanisms. We found that the levels of RUNX2 expression in gastric cancer tissues were correlated with the differentiation degrees, invasion depth and lymph node metastasis. COX regression analysis indicated that RUNX2 was an independent prognostic indicator for GC patients. RUNX2 significantly increased the migration and invasion ability of GC cells in vitro and enhanced the invasion and metastatic potential of GC cells in an orthotopic GC model of nude mice. Mechanistically, RUNX2 directly bound to the promoter region of the gene coding for the chemokine receptor CXCR4 to enhance its transcription. CXCR4 knockdown or treatment with AMD3100, a CXCR4 inhibitor, attenuated RUNX2-promoted invasion and metastasis. These results demonstrate that RUNX2 promotes the invasion and metastasis of human GC by transcriptionally up-regulating the chemokine receptor CXCR4. Therefore, the RUNX2-CXCR4 axis is a potential therapeutic target for GC.

Paracrine SDF-1α signaling mediates the effects of PSCs on GEM chemoresistance through an IL-6 autocrine loop in pancreatic cancer cells

Pancreatic cancer exhibits the poorest prognosis among all tumors and is characterized by high resistance to the currently available chemotherapeutic agents. Our previous studies have suggested that stromal components could promote the chemoresistance of pancreatic cancer cells (PCCs). Here, we explored the roles of pancreatic stellate cells (PSCs) and the SDF-1α/CXCR4 axis in pancreatic cancer chemoresitance. Our results showed that primary PSCs typically expressed SDF-1α, whereas its receptor CXCR4 was highly expressed in PCCs. PSC-conditioned medium (PSC-CM) inhibited Gemcitabine (GEM)-induced cytotoxicity and apoptosis in the human PCC line Panc-1, which was antagonized by an SDF-1α neutralizing Ab. Recombinant human SDF-1α (rhSDF-1α) increased IL-6 expression and secretion in Panc-1 cells in a time and dose-dependent manner, and this effect was suppressed by the CXCR4 antagonist AMD3100. rhSDF-1α protected Panc-1 cells from GEM-induced apoptosis, and the protective effect was significantly reduced by blocking IL-6 using a neutralizing antibody. Moreover, rhSDF-1α increased FAK, ERK1/2, AKT and P38 phosphorylation in Panc-1 cells, and either FAK or ERK1/2 inhibition suppressed SDF-1α-upregulated IL-6 expression. SDF-1α-induced AKT activation was almost completely blocked by FAK inhibition. In conclusion, we demonstrate for the first time that PSCs promote the chemoresistance of PCCs to GEM, and this effect is mediated by paracrine SDF-1α/CXCR4 signaling-induced activation of the intracellular FAK-AKT and ERK1/2 signaling pathways and a subsequent IL-6 autocrine loop in PCCs. Our findings indicate that blocking the PSC-PCC interaction by inhibiting SDF-1α/CXCR4 signaling may be a promising therapeutic strategy for overcoming chemoresistance in pancreatic cancer.

Extracellular vesicles from bone marrow mesenchymal stem/stromal cells transport tumor regulatory microRNA, proteins, and metabolites

Human mesenchymal stem/stromal cells (hMSCs) have been shown to support breast cancer cell proliferation and metastasis, partly through their secretome. hMSCs have a remarkable ability to survive for long periods under stress, and their secretome is tumor supportive. In this study, we have characterized the cargo of extracellular vesicular (EV) fraction (that is in the size range of 40-150nm) of serum deprived hMSCs (SD-MSCs). Next Generation Sequencing assays were used to identify small RNA secreted in the EVs, which indicated presence of tumor supportive miRNA. Further assays demonstrated the role of miRNA-21 and 34a as tumor supportive miRNAs. Next, proteomic assays revealed the presence of ≈150 different proteins, most of which are known tumor supportive factors such as PDGFR-β, TIMP-1, and TIMP-2. Lipidomic assays verified presence of bioactive lipids such as sphingomyelin. Furthermore, metabolite assays identified the presence of lactic acid and glutamic acid in EVs. The co-injection xenograft assays using MCF-7 breast cancer cells demonstrated the tumor supportive function of these EVs. To our knowledge this is the first comprehensive -omics based study that characterized the complex cargo of extracellular vesicles secreted by hMSCs and their role in supporting breast cancers.

Mist1 Expressing Gastric Stem Cells Maintain the Normal and Neoplastic Gastric Epithelium and Are Supported by a Perivascular Stem Cell Niche

The regulation and stem cell origin of normal and neoplastic gastric glands are uncertain. Here, we show that Mist1 expression marks quiescent stem cells in the gastric corpus isthmus. Mist1(+) stem cells serve as a cell-of-origin for intestinal-type cancer with the combination of Kras and Apc mutation and for diffuse-type cancer with the loss of E-cadherin. Diffuse-type cancer development is dependent on inflammation mediated by Cxcl12(+) endothelial cells and Cxcr4(+) gastric innate lymphoid cells (ILCs). These cells form the perivascular gastric stem cell niche, and Wnt5a produced from ILCs activates RhoA to inhibit anoikis in the E-cadherin-depleted cells. Targeting Cxcr4, ILCs, or Wnt5a inhibits diffuse-type gastric carcinogenesis, providing targets within the neoplastic gastric stem cell niche.

Paracrine tumor signaling induces transdifferentiation of surrounding fibroblasts

Growth stimuli in cancer growth resemble those exhibited in wound healing. However, the process of nemosis is absent in cancer-associated fibroblasts (CAFs), which remain constitutively active. CAFs are present in almost all solid tumors but are most abundant in breast, prostate and pancreatic cancers. TGF-β1, TGF-β2, PDGF, IL-6, bFGF, reactive oxide species and protein kinase C are considered the key players in tumor-induced transdifferentiation of surrounding fibroblasts. Full-extent transdifferentiation was obtained only when the medium contained TGF-β1 or TGF-β2 (with or without other factors), whereas PDGF, bFGF or IL-6 (each alone) induced only partial transdifferentiation. Recent evidence suggests that the fibroblasts associated with primary cancers differ from those associated with metastases. The metastases-associated fibroblasts are converted by a metastasis-specific spectrum of factors. A large portion of paracrine tumor signaling is mediated by cancer cell-derived vesicles termed exosomes and microvesicles. The cancer cell-derived exosomes contain abundant and diverse proteomes and a number of signaling factors (TGF-ß1, TGF-ß2, IL-6, MMP2 and MMP9), particularly under hypoxic conditions. In contrast to the traditional view, the clonal expansion and selection of neoplastic cells should not be viewed outside the host body context. It is vital for a neoplastic cell to achieve the ability to re-program host body cells into CAFs and by this influence to modulate its microenvironment and receive positive feedback for growth and drug resistance. Neoplastic cells, which fail to develop such capacity, do not pass critical barriers in tumorigenesis and remain dormant and benign.

Current Status on Stem Cells and Cancers of the Gastric Epithelium

Gastric cancer is still a leading cause of cancer-related mortality worldwide in spite of declining incidence. Gastric cancers are, essentially, adenocarcinomas and one of the strongest risk factors is still infection with Helicobacter pylori. Within the last years, it became clear that gastric self-renewal and carcinogenesis are intimately linked, particularly during chronic inflammatory conditions. Generally, gastric cancer is now regarded as a disease resulting from dysregulated differentiation of stem and progenitor cells, mainly due to an inflammatory environment. However, the situation in the stomach is rather complex, consisting of two types of gastric units which show bidirectional self-renewal from an unexpectedly large variety of progenitor/stem cell populations. As in many other tumors, cancer stem cells have also been characterized for gastric cancer. This review focuses on the various gastric epithelial stem cells, how they contribute to self-renewal and which routes are known to gastric adenocarcinomas, including their stem cells.

Caveolin-1 is a modulator of fibroblast activation and a potential biomarker for gastric cancer

Stromal fibroblasts play an important role in chronic cancer-related inflammation and the development as well as progression of malignant diseases. However, the difference and relationship between inflammation-associated fibroblasts (IAFs) and cancer-associated fibroblasts (CAFs) are poorly understood. In this study, gastric cancer-associated fibroblasts (GCAFs) and their corresponding inflammation-associated fibroblasts (GIAFs) were isolated from gastric cancer (GC) with chronic gastritis and cultured in vitro. These activated fibroblasts exhibited distinct secretion and tumor-promoting behaviors in vitro. Using proteomics and bioinformatics techniques, caveolin-1 (Cav-1) was identified as a major network-centric protein of a sub-network consisting of 121 differentially expressed proteins between GIAFs and GCAFs. Furthermore, immunohistochemistry in a GC cohort showed significant difference in Cav-1 expression score between GIAFs and GCAFs and among patients with different grades of chronic gastritis. Moreover, silencing of Cav-1 in GIAFs and GCAFs using small interfering RNA increased the production of pro-inflammatory and tumor-enhancing cytokines and chemokines in conditioned mediums that elevated cell proliferation and migration when added to GC cell lines AGS and MKN45 in vitro. In addition, Cav-1 status in GIAFs and GCAFs independently predicted the prognosis of GC. Our findings indicate that Cav-1 loss contributes to the distinct activation statuses of fibroblasts in GC microenvironment and gastritis mucosa, and Cav-1 expression in both GCAFs and GIAFs may serve as a potential biomarker for GC progression.

Ponicidin induces apoptosis via JAK2 and STAT3 signaling pathways in gastric carcinoma

Ponicidin has a variety of biological effects such as immunoregulatory and anti-inflammatory functions as well as anti-viral functions especially in the upper respiratory tract infection. This study was aimed to elucidate the antitumor effect of ponicidin in gastric carcinoma MKN28 cells and the possible molecular mechanism involved. Cell viability was measured by the Cell Count Kit-8 (CCK8). Cell apoptosis was assessed by flow cytometry as well as cell cycle and reactive oxygen species (ROS) analysis. Western blot analysis was used to detect the active form of caspase-3 as well as Bax and B-cell lymphoma-2 (Bcl-2) expressions after cells were treated with different concentrations of ponicidin. The results revealed that ponicidin could inhibit the growth of MKN28 cells significantly in both a time- and dose-dependent manner. The cell cycle was blocked and ROS generation was increased after the cells were treated with ponicidin. Bcl-2 expression was down-regulated remarkably while Bax expression and the active form of caspase-3 were increased after apoptosis occurred. We therefore conclude that ponicidin exhibited significant growth inhibition of gastric carcinoma cell line MKN28 and induced apoptosis of MKN28 cells via the signaling pathway regulated by Janus kinase 2 (JAK2) and signal transducers and activators of transcription 3 (STAT3). Ponicidin may serve as a potential therapeutic agent for gastric carcinoma.

OCT1 is a determinant of synbindin-related ERK signalling with independent prognostic significance in gastric cancer

OBJECTIVE

Octamer transcription factor 1 (OCT1) was found to be expressed in intestinal metaplasia and gastric cancer (GC), but the exact roles of OCT1 in GC remain unclear. The objective of this study was to determine the functional and prognostic implications of OCT1 in GC.

DESIGN

Expression of OCT1 was examined in paired normal and cancerous gastric tissues and the prognostic significance of OCT1 was analysed by univariate and multivariate survival analyses. The functions of OCT1 on synbindin expression and extracellular signal-regulated kinase (ERK) phosphorylation were studied in vitro and in xenograft mouse models.

RESULTS

The OCT1 gene is recurrently amplified and upregulated in GC. OCT1 overexpression and amplification are associated with poor survival in patients with GC and the prognostic significance was confirmed by independent patient cohorts. Combining OCT1 overexpression with American Joint Committee on Cancer staging improved the prediction of survival in patients with GC. High expression of OCT1 associates with activation of the ERK mitogen-activated protein kinase signalling pathway in GC tissues. OCT1 functions by transactivating synbindin, which binds to ERK DEF domain and facilitates ERK phosphorylation by MEK. OCT1-synbindin signalling results in the activation of ERK substrates ELK1 and RSK, leading to increased cell proliferation and invasion. Immunofluorescent study of human GC tissue samples revealed strong association between OCT1 protein level and synbindin expression/ERK phosphorylation. Upregulation of OCT1 in mouse xenograft models induced synbindin expression and ERK activation, leading to accelerated tumour growth in vivo.

CONCLUSIONS

OCT1 is a driver of synbindin-mediated ERK signalling and a promising marker for the prognosis and molecular subtyping of GC.

Interaction between gastric cancer stem cells and the tumor microenvironment

Gastric cancer (GC) remains a leading cause of cancer-related deaths worldwide. Cancer stem cells (CSCs) are selectively capable of tumor initiation and are implicated in tumor relapse and metastasis, thus, governing the prognosis of GC patients. Stromal cells and extracellular matrix adjacent to cancer cells are known to form a supportive environment for cancer progression. CSC properties are also regulated by their microenvironment through cell signaling and related factors. This review presents the current findings regarding the influence of the tumor microenvironment on GC stem cells, which will support the development of novel therapeutic strategies for patients with GC.

Obesity accelerates Helicobacter felis-induced gastric carcinogenesis by enhancing immature myeloid cell trafficking and TH17 response

OBJECTIVE

To investigate the role of obesity-associated inflammation and immune modulation in gastric carcinogenesis during Helicobacter-induced chronic gastric inflammation.

DESIGN

C57BL/6 male mice were infected with H felis and placed on a high-fat diet (45% calories from fat). Study animals were analysed for gastric and adipose pathology, inflammatory markers in serum, stomach and adipose tissue, and immune responses in blood, spleen, stomach and adipose tissue.

RESULTS

H felis-induced gastric carcinogenesis was accelerated in diet-induced obese mice compared with lean controls. Obesity increased bone marrow-derived immature myeloid cells in blood and gastric tissue of H felis-infected mice. Obesity also led to elevations in CD4 T cells, IL-17A, granulocyte macrophage colony-stimulating factor, phosphorylated STAT3 and prosurvival gene expression in gastric tissue of H felis-infected mice. Conversely, in adipose tissue of obese mice, H felis infection increased macrophage accumulation and expression of IL-6, C-C motif ligand 7 (CCL7) and leptin. Finally, the combination of obesity and gastric inflammation synergistically increased serum proinflammatory cytokines, including IL-6.

CONCLUSIONS

Here, we have established a model to study the molecular mechanism by which obesity predisposes individuals to gastric cancer. In H felis-infected mice, obesity increased proinflammatory immune responses and accelerated gastric carcinogenesis. Interestingly, gastric inflammation augmented obesity-induced adipose inflammation and production of adipose-derived factors in obese, but not lean, mice. Our findings suggest that obesity accelerates Helicobacter-associated gastric cancer through cytokine-mediated cross-talk between inflamed gastric and adipose tissues, augmenting immune responses at both tissue sites, and thereby contributing to a protumorigenic gastric microenvironment.

Gastritis promotes an activated bone marrow-derived mesenchymal stem cell with a phenotype reminiscent of a cancer-promoting cell

BACKGROUND

Bone marrow-derived mesenchymal stem cells (BM-MSCs) promote gastric cancer in response to gastritis. In culture, BM-MSCs are prone to mutation with continued passage but it is unknown whether a similar process occurs in vivo in response to gastritis.

AIM

The purpose of this study was to identify the role of chronic gastritis in the transformation of BM-MSCs leading to an activated cancer-promoting phenotype.

METHODS

Age matched C57BL/6 (BL/6) and gastrin deficient (GKO) mice were used for isolation of stomach, serum and mesenchymal stem cells (MSCs) at 3 and 6 months of age. MSC activation was assessed by growth curve analysis, fluorescence-activated cell sorting and xenograft assays. To allow for the isolation of bone marrow-derived stromal cells and assay in response to chronic gastritis, IRG/Vav-1(Cre) mice that expressed both enhanced green fluorescent protein-expressing hematopoietic cells and red fluorescent protein-expressing stromal cells were generated. In a parabiosis experiment, IRG/Vav-1(Cre) mice were paired to either an uninfected Vav-1(Cre) littermate or a BL/6 mouse inoculated with Helicobacter pylori.

RESULTS

GKO mice displayed severe atrophic gastritis accompanied by elevated gastric tissue and circulating transforming growth factor beta (TGFβ) by 3 months of age. Compared to BM-MSCs isolated from uninflamed BL/6 mice, BM-MSCs isolated from GKO mice displayed an increased proliferative rate and elevated phosphorylated-Smad3 suggesting active TGFβ signaling. In xenograft assays, mice injected with BM-MSCs from 6-month-old GKO animals displayed tumor growth. RFP+ stromal cells were rapidly recruited to the gastric mucosa of H. pylori parabionts and exhibited changes in gene expression.

CONCLUSIONS

Gastritis promotes the in vivo activation of BM-MSCs to a phenotype reminiscent of a cancer-promoting cell.

CXC chemokines and chemokine receptors in gastric cancer: From basic findings towards therapeutic targeting

Gastric cancer is the fourth most common cancer, and the second-highest cause of cancer-related deaths worldwide. Despite extensive research to identify novel diagnostic and therapeutic agents, patients with advanced gastric cancer suffer from a poor quality of life and poor prognosis, and treatment is dependent mainly on conventional cytotoxic chemotherapy. To improve the quality of life and survival of gastric cancer patients, a better understanding of the underlying molecular pathologies, and their application towards the development of novel targeted therapies, is urgently needed. Chemokines are a group of small proteins associated with cytoskeletal rearrangements, the directional migration of several cell types during development and physiology, and the host immune response via interactions with G-protein coupled receptors. There is also growing evidence to suggest that chemokines not only play a role in the immune system, but are also involved in the development and progression of tumors. In gastric cancer, CXC chemokines and chemokine receptors regulate the trafficking of cells in and out of the tumor microenvironment. CXC chemokines and their receptors can also directly influence tumorigenesis by modulating tumor transformation, survival, growth, invasion and metastasis, as well as indirectly by regulating angiogenesis, and tumor-leukocyte interactions. In this review, we will focus on the roles of CXC chemokines and their receptors in the development, progression, and metastasis of gastric tumors, and discuss their therapeutic potential for gastric cancer.

Effect of Helicobacter pylori infection on stromal-derived factor-1/CXCR4 axis in bone marrow-derived mesenchymal stem cells

Background:

Recent studies have demonstrated that during chronic Helicobacter pylori (H. pylori) infection bone marrow-derived-mesenchymal stem cells (BMD-MSCs) migrate to the gastric tissue and could be also the origin of gastric adenocarcinoma. The chemokine CXCR4 through binding to its ligand stromal-derived factor (SDF-1) plays a crucial role in migration of inflammatory and stem cells. However, the possible effect of H. pylori infection on the SDF-1/CXCR4 axis has not yet been elucidated.

Materials and Methods:

Gastric epithelial cell line, AGS, and BMD-MSCs were cocultured with H. pylori for 24 h. The expression of CXCR4 was examined in BMD-MSCs by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and flow cytometry, and SDF-1 expression in AGS cells was detected by qRT-PCR and enzyme-linked immunosorbent assay. Further, migration of BMD-MSCs toward SDF-1 was evaluated by chemotaxis assay.

Results:

We found that coculture of H. pylori with BMD-MSCs or AGS: (i) enhanced CXCR4 expression on the cell surface of BMD-MSCs and (ii) increased SDF-1 secretion by AGS cells. Consistently, we observed that H. pylori-treated BMD-MSCs showed a higher capability to migrate toward SDF-1 gradient compared with untreated cells.

Conclusion:

We found that H. pylori upregulates CXCR4 expression in BMD-MSCs and enhance their migration toward SDF-1. This study provides the first evidence that H. pylori infection may enhance BMD-MSC migration through acting on the SDF-1/CXCR4 axis.

Carcinoma-associated fibroblasts provide operational flexibility in metastasis

Malignant cancer cells do not act as lone wolves to achieve metastasis, as they exist within a complex ecosystem consisting of an extracellular matrix scaffold populated by carcinoma-associated fibroblasts (CAFs), endothelial cells and immune cells. We recognize local (primary tumor) and distant ecosystems (metastasis). CAFs, also termed myofibroblasts, may have other functions in the primary tumor versus the metastasis. Cellular origin and tumor heterogeneity lead to the expression of specific markers. The molecular characteristics of a CAF remain in evolution since CAFs show operational flexibility. CAFs respond dynamically to a cancer cell's fluctuating demands by shifting profitable signals necessary in metastasis. Local, tissue-resident fibroblasts and mesenchymal stem cells (MSCs) coming from reservoir sites such as bone marrow and adipose tissue are the main progenitor cells of CAFs. CAFs may induce awakening from metastatic dormancy, a major cause of cancer-specific death. Cancer management protocols influence CAF precursor recruitment and CAF activation. Since CAF signatures represent early changes in metastasis, including formation of pre-metastatic niches, we discuss whether liquid biopsies, including exosomes, may detect and monitor CAF reactions allowing optimized prognosis of cancer patients.

Sonic hedgehog mediates the proliferation and recruitment of transformed mesenchymal stem cells to the stomach

Studies using Helicobacter-infected mice show that bone marrow-derived mesenchymal stem cells (MSCs) can repopulate the gastric epithelium and promote gastric cancer progression. Within the tumor microenvironment of the stomach, pro-inflammatory cytokine interferon-gamma (IFNγ) and Sonic hedgehog (Shh) are elevated. IFNγ is implicated in tumor proliferation via activation of the Shh signaling pathway in various tissues but whether a similar mechanism exists in the stomach is unknown. We tested the hypothesis that IFNγ drives MSC proliferation and recruitment, a response mediated by Shh signaling. The current study uses transplantation of an in vitro transformed mesenchymal stem cell line (stMSC^vect), that over-expresses hedgehog signaling, in comparison to non-transformed wild-type MSCs (wtMSCs), wtMSCs transfected to over-express Shh (wtMSC^Shh), and stMSCs transduced with lentiviral constructs containing shRNA targeting the Shh gene (stMSC^ShhKO). The effect of IFNγ on MSC proliferation was assessed by cell cycle analysis in vitro using cells treated with recombinant IFNγ (rmIFNγ) alone, or in combination with anti-Shh 5E1 antibody, and in vivo using mice transplanted with MSCs treated with PBS or rmIFNγ. In vitro, IFNγ significantly increased MSC proliferation, a response mediated by Shh that was blocked by 5E1 antibody. The MSC population collected from bone marrow of PBS- or IFNγ-treated mice showed that IFNγ significantly increased the percentage of all MSC cell lines in S phase, with the exception of the stMSCs^ShhKO cells. While the MSC cell lines with intact Shh expression were recruited to the gastric mucosa in response to IFNγ, stMSCs^ShhKO were not. Hedgehog signaling is required for MSC proliferation and recruitment to the stomach in response to IFNγ.

Cancer stem cells: the 'heartbeat' of gastric cancer

Gastric cancer (GC) remains one of the most common cancers worldwide. Its prevalence is still on the rise in the developing countries due to the ageing population. The cancer stem cell (CSC) theory provides a new insight into the interpretation of tumor initiation, aggressive growth, recurrence, and metastasis of cancer, as well as the development of new strategies for cancer treatment. This review will focus on the progress of biomarkers and signaling pathways of CSCs, the complex crosstalk networks between the microenvironment and CSCs, and the development of therapeutic approaches against CSCs, predominantly focusing on GC.

The evolution of the cancer niche during multistage carcinogenesis

The concept of the tumour microenvironment recognizes that the interplay between cancer cells and stromal cells is a crucial determinant of cancer growth. In this Perspectives article, we propose the novel concept that the tumour microenvironment is built through rate-limiting steps during multistage carcinogenesis. Construction of a 'precancer niche' is a necessary and early step that is required for initiated cells to survive and evolve; subsequent niche expansion and maturation accompany tumour promotion and progression, respectively. As such, cancer niches represent an emergent property of a tumour that could be a robust target for cancer prevention and therapy.

The gastrointestinal tumor microenvironment

Over the past decade, the microenvironment of gastrointestinal tumors has gained increasing attention because it is required for tumor initiation, progression, and metastasis. The tumor microenvironment has many components and has been recognized as one of the major hallmarks of epithelial cancers. Although therapeutic strategies for gastrointestinal cancer have previously focused on the epithelial cell compartment, there is increasing interest in reagents that alter the microenvironment, based on reported interactions among gastrointestinal epithelial, stromal, and immune cells during gastrointestinal carcinogenesis. We review the different cellular components of the gastrointestinal tumor microenvironment and their functions in carcinogenesis and discuss how improving our understanding of the complex stromal network could lead to new therapeutic strategies.