Inhibition of STAT3 in gastric cancer: role of pantoprazole as SHP-1 inducer

Antagonizing roles of SHP1 in the pathogenesis of Helicobacter pylori infection

BACKGROUND

SHP1 has been documented as a tumor suppressor and it was thought to play an antagonistic role in the pathogenesis of Helicobacter pylori infection. In this study, the exact mechanism of this antagonistic action was studied.

MATERIALS AND METHODS

AGS, MGC803, and GES-1 cells were infected with H. pylori, intracellular distribution changes of SHP1 were first detected by immunofluorescence. SHP1 overexpression and knockdown were then constructed in these cells to investigate its antagonistic roles in H. pylori infection. Migration and invasion of infected cells were detected by transwell assay, secretion of IL-8 was examined via ELISA, the cells with hummingbird-like alteration were determined by microexamination, and activation of JAK2/STAT3, PI3K/Akt, and ERK pathways were detected by immunoblotting. Mice infection model was established and gastric pathological changes were evaluated. Finally, the SHP1 activator sorafenib was used to analyze the attenuating effect of SHP1 activation on H. pylori pathogenesis in vitro and in vivo.

RESULTS

The sub-localization of SHP1 changed after H. pylori infection, specifically that the majority of the cytoplasmic SHP1 was transferred to the cell membrane. SHP1 inhibited H. pylori-induced activation of JAK2/STAT3 pathway, PI3K/Akt pathway, nuclear translocation of NF-κB, and then reduced EMT, migration, invasion, and IL-8 secretion. In addition, SHP1 inhibited the formation of CagA-SHP2 complex by dephosphorylating phosphorylated CagA, reduced ERK phosphorylation and the formation of CagA-dependent hummingbird-like cells. In the mice infection model, gastric pathological changes were observed and increased IL-8 secretion, indicators of cell proliferation and EMT progression were also detected. By activating SHP1 with sorafenib, a significant curative effect against H. pylori infection was obtained in vitro and in vivo.

CONCLUSIONS

SHP1 plays an antagonistic role in H. pylori pathogenesis by inhibiting JAK2/STAT3 and PI3K/Akt pathways, NF-κB nuclear translocation, and CagA phosphorylation, thereby reducing cell EMT, migration, invasion, IL-8 secretion, and hummingbird-like changes.

Euphorbiasteroid Induces Apoptosis as Well as Autophagy through Modulating SHP-1/STAT3 Pathway in Hepatocellular Carcinoma Cells

Euphorbiasteroid (EPBS) has gained attention for its activity against human lung cancer and sarcoma; however, its impact on hepatocellular carcinoma has not yet been elucidated. Here, we investigated the cytotoxic effect of EPBS on human hepatocellular carcinoma (HCC) cells. We found that EPBS induced both apoptosis and autophagy in HCC cells. Additionally, we observed that EPBS treatment suppressed the constitutive as well as the inducible activation of a signal transducer and activator of transcription 3 (STAT3) protein expression. Moreover, EPBS promoted the expression of SHP-1 protein and the production of reactive oxidative stress (ROS). Furthermore, the knockdown of SHP-1 by siRNA transfection reversed the effects of EPBS, which have inductive effects related to apoptosis and autophagy. Therefore, EPBS can potentially function as an anti-cancer agent by inducing apoptosis and autophagy when targeting the SHP-1/STAT3 pathway.

Systemic Analysis of the Anticancer Effects of Sijunzi Decoction on Gastric Cancer Based on Network Pharmacology

Objective:

Sijunzi decoction (SJZD) has been used for alleviating peptic ulcer or gastric discomfort, and treating spleen disorders since the Song Dynasty, but its pharmacological effect on human gastric cancer (GC) is still unclear. In this research, a network pharmacology-based strategy was applied to explore active ingredients, potential targets, and molecular mechanisms of SJZD against GC.

Methods:

The active compounds and potential targets of SJZD, as well as GC-associated gene targets, were retrieved from publicly available databases. Bioinformatics approaches were used to assess the network interaction, functional regulation, and signaling pathways between SJZD ingredients and GC targets. The anticancer effects of SJZD against GC were verified in vivo by a mouse subcutaneous model.

Results:

The results of network analysis showed that quercetin was the most active ingredient in SJZD. Several prominent target genes of SJZD were identified, such as AKT1 and STAT3. Gene ontology analysis revealed that the core anti-GC targets of SJZD included transcription factor activity and kinase activity. Pathway enrichment analysis indicated that GC patients could be benefited from SJZD treatment via modulation of signaling pathways related to endocrine system, cancer, and infectious disease. Furthermore, in vivo experiments showed that high-dose SJZD could inhibit GC xenograft tumor growth, reduce GC cell proliferation, induce GC cell apoptosis, and decrease the expression of p-AKT1 and p-STAT3.

Conclusions:

Taken together, our results suggest that SJZD can serve as an effective adjuvant therapeutic agent for GC patients.

Glycerophosphoinositol Promotes Apoptosis of Chronic Lymphocytic Leukemia Cells by Enhancing Bax Expression and Activation

An imbalance in the expression of pro- and anti-apoptotic members of the Bcl-2 family of apoptosis-regulating proteins is one of the main biological features of CLL, highlighting these proteins as therapeutic targets for treatment of this malignancy. Indeed, the Bcl-2 inhibitor Venetoclax is currently used for both first-line treatment and treatment of relapsed or refractory CLL. An alternative avenue is the transcriptional modulation of Bcl-2 family members to tilt their balance towards apoptosis. Glycerophosphoinositol (GroPIns) is a biomolecule generated from membrane phosphoinositides by the enzymes phospholipase A2 and lysolipase that pleiotropically affects key cellular functions. Mass-spectrometry analysis of GroPIns interactors recently highlighted the ability of GroPIns to bind to the non-receptor tyrosine phosphatase SHP-1, a known promoter of Bax expression, suggesting that GroPIns might correct the Bax expression defect in CLL cells, thereby promoting their apoptotic demise. To test this hypothesis, we cultured CLL cells in the presence of GroPIns, alone or in combination with drugs commonly used for treatment of CLL. We found that GroPIns alone increases Bax expression and apoptosis in CLL cells and enhances the pro-apoptotic activity of drugs used for CLL treatment in a SHP-1 dependent manner. Interestingly, among GroPIns interactors we found Bax itself. Short-term treatments of CLL cells with GroPIns induce Bax activation and translocation to the mitochondria. Moreover, GroPIns enhances the pro-apoptotic activity of Venetoclax and Fludarabine in CLL cells. These data provide evidence that GroPIns exploits two different pathways converging on Bax to promote apoptosis of leukemic cells and pave the way to new studies aimed at testing GroPIns in combination therapies for the treatment of CLL.

CLEC12B suppresses lung cancer progression by inducing SHP-1 expression and inactivating the PI3K/AKT signaling pathway

Lung cancer is the leading cause of cancer mortality worldwide. CLEC12B, a C-type lectin-like receptor, is low-expressed in lung cancer tissues. However, the function of CLEC12B in lung cancer and its underlying mechanism remain unclear. Here, an obvious down-regulation of CLEC12B was observed in lung cancer cells compared with the normal lung epithelial cells. CLEC12B over-expression suppressed cell viability and cell cycle entry in lung cancer, along with the reduction of PCNA and cyclin D1 expressions, while silencing CLEC12B possessed the opposite effects. Over-expression of CLEC12B promoted lung cancer cell apoptosis, accompanied by decreased Bcl-2 and increased Bax, cleaved caspase-3 and cleaved caspase-9. Moreover, CLEC12B decreased phosphorylation of PI3K-p85 and AKT proteins. By contrast, CLEC12B knockdown activated the PI3K/AKT pathway. In vivo, CLEC12B inhibited tumor growth in lung cancer, which can be reversed by CLEC12B inhibition. Co-IP and immunofluorescence assays confirmed the interaction between CLEC12B and SHP-1, and CLEC12B over-expression increased SHP-1 level. Furthermore, knocking down SHP-1 abrogated the above biological phenotypes caused by CLEC12B elevation. Taken together, our findings demonstrate that CLEC12B serves as a tumor-suppressing gene in lung cancer through positively regulating SHP-1 expression, which may be mediated by the PI3K/AKT signaling pathway.

BAPST. A Combo of Common use drugs as metabolic therapy of cancer-a theoretical proposal

Advances in cancer therapy have yet to impact worldwide cancer mortality. Poor cancer drug affordability is one of the factors limiting mortality burden strikes. Up to now, cancer drug repurposing had no meet expectations concerning drug affordability. The three FDA-approved cancer drugs developed under repurposing -all-trans-retinoic acid, arsenic trioxide, and thalidomide- do not differ in price from other drugs developed under the classical model. Though additional factors affect the whole process from inception to commercialization, the repurposing of widely used, commercially available, and cheap drugs may help. This work reviews the concept of the malignant metabolic phenotype and its exploitation by simultaneously blocking key metabolic processes altered in cancer. We elaborate on a combination called BAPST, which stands for the following drugs and pathways they inhibit: Benserazide (glycolysis), Apomorphine (glutaminolysis), Pantoprazole (Fatty-acid synthesis), Simvastatin (mevalonate pathway), and Trimetazidine (Fatty-acid oxidation). Their respective primary indications are: • Parkinson's disease (benserazide and apomorphine). • Peptic ulcer disease (pantoprazole). • Hypercholesterolemia (simvastatin). • Ischemic heart disease (trimetazidine). When used for their primary indication, the literature review on each of these drugs shows they have a good safety profile and lack predicted pharmacokinetic interaction among them. Most importantly, the inhibitory enzymatic concentrations required for inhibiting their cancer targets enzymes are below the plasma concentrations observed when these drugs are used for their primary indication. Based on that, we propose that the regimen BAPTS merits preclinical testing.

Effect of pantoprazole on I-R-induced myocardial injury in diabetic rats targeting inflammatory cytokine release and oxidative stress

OBJECTIVES

To evaluate the pleiotropic potential and underlying mechanism of pantoprazole (PPZ) (common Proton Pump Inhibitors, PPIs) in type 2 diabetes mellitus (T2DM) -associated ischemia/reperfusion (I-R)-induced myocardial infarction which is still uncharted. Whereas some other PPIs have demonstrated their anti-diabetic, antioxidant, and anti-inflammatory potential.

MATERIALS AND METHODS

We evaluated the potential of coinciding treatment of PPZ (4 mg/kg/po/day for 8 weeks) in Wistar albino rats against STZ (50 mg/kg/IP) induced T2DM model and I-R provoked cardiac infarction model in diabetic and non-diabetic condition.

RESULTS

PPZ significantly inhibited the perturbed deviations in blood glucose concentration, HbA1c, C-peptide, plasma insulin, and ameliorated the lipid profile (dyslipidemia). PPZ protected myocardial tissue against lipid peroxidation by restoring the levels of serum TBARS and reduced NBT. The significant protective effects of PPZ were evident by ameliorating CKMB, LDH, cTnI, and myocardial oxidative stress in PPZ treated animals. Additionally, PPZ prominently reduced various proinflammatory cytokines release including TGF-β1, TNF-α, and IL-6. PPZ upsurges the bioavailability of nitrite/nitrate concentration which may pacify the impact of myocardial infarction in diabetic I-R injury.

CONCLUSION

The consequences indicate that PPZ possesses a potent protective effect against diabetic I-R-induced myocardial infarction via suppressing oxidative stress, inflammation, and dyslipidemia-associated tissue damage.

The role of Src homology region 2 domain-containing phosphatase-1 hypermethylation in the classification of patients with myelodysplastic syndromes and its association with signal transducer and activator of transcription 3 phosphorylation in skm-1 cells

INTRODUCTION

Myelodysplastic syndromes (MDS) are a group of heterogeneous bone marrow clonal diseases characterized by the abnormal differentiation and development of bone marrow cells. Src homology region 2 domain-containing phosphatase (SHP)-1 is an important tumor suppressor gene that regulates the signal transducer and activator of transcription (STAT) pathway.

METHODS

Survival analysis was performed to evaluate the function of decitabine (5-Aza) in treating MDS patients with and without SHP-1 methylation. The effects of 5-Aza treatment on SHP-1 expression and methylation and STAT3 phosphorylation were investigated in MDS cells by methylation-specific PCR, reverse transcription PCR, and western blotting. Cell viability and apoptosis were similarly evaluated by MTT assay and flow cytometry.

RESULTS

High-risk MDS patients showed significant SHP-1 hypermethylation compared with low-risk patients, and patients with no SHP-1 methylation had longer overall survival. SHP-1 expression was significantly increased at mRNA and protein levels following 5-Aza treatment, while the phosphorylation of STAT3 protein was significantly decreased. Apoptosis increased significantly in MDS cells treated with higher doses of 5-Aza while cell viability decreased significantly.

CONCLUSION

SHP-1 hypermethylation was associated with poor prognosis in HR patients with MDS, suggesting it could be used as a prognostic indicator.

A comprehensive review on the role of protein tyrosine phosphatases in gastric cancer development and progression

The main post-translational reversible modulation of proteins is phosphorylation and dephosphorylation, catalyzed by protein kinases (PKs) and protein phosphatases (PPs) which is crucial for homeostasis. Imbalance in this crosstalk can be related to diseases, including cancer. Plenty of evidence indicates that protein tyrosine phosphatases (PTPs) can act as tumor suppressors and tumor promoters. In gastric cancer (GC), there is a lack of understanding of the molecular aspects behind the tumoral onset and progression. Here we describe several members of the PTP family related to gastric carcinogenesis. We discuss the associated molecular mechanisms which support the down or up modulation of different PTPs. We emphasize the Helicobacter pylori (H. pylori) virulence which is in part associated with the activation of PTP receptors. We also explore the involvement of intracellular redox state in response to H. pylori infection. In addition, some PTP members are under influence by genetic mutations, epigenetics mechanisms, and miRNA modulation. The understanding of multiple aspects of PTPs in GC may provide new targets and perspectives on drug development.

Emerging impact of the long noncoding RNA MIR22HG on proliferation and apoptosis in multiple human cancers

An increasing number of studies have shown that long noncoding RNAs (lncRNAs) play important roles in diverse cellular processes, including proliferation, apoptosis, migration, invasion, chromatin remodeling, metabolism and immune escape. Clinically, the expression of MIR22HG is increased in many human tumors (colorectal cancer, gastric cancer, hepatocellular carcinoma, lung cancer, and thyroid carcinoma), while in others (esophageal adenocarcinoma and glioblastoma), it is significantly decreased. Moreover, MIR22HG has been reported to function as a competitive endogenous RNA (ceRNA), be involved in signaling pathways, interact with proteins and interplay with miRNAs as a host gene to participate in tumorigenesis and tumor progression. In this review, we describe the biological functions of MIR22HG, reveal its underlying mechanisms for cancer regulation, and highlight the potential role of MIR22HG as a novel cancer prognostic biomarker and therapeutic target that can increase the efficacy of immunotherapy and targeted therapy for cancer treatment.

Omeprazole and adenocarcinoma in the stomach of rats submitted to duodenogastric reflux. Is there a protective effect?

Purpose:

To investigate the role of omeprazole and nitrites on the gastric mucosa of rats submitted to specific techniques to induce duodenogastric reflux.

Methods:

One hundred and twenty Wistar rats were divided into three groups: Group I (n=40) -gastrotomy; Group II (n=40) - duodenogastric reflux after gastrojejunoanastomosis latero-lateral (DGR); Group III (n=40) - retrograde duodenogastric reflux through the pylorus (DGR-P). The groups were divided into 4 subgroups of 10 animals, respectively treated for 16 weeks with water, omeprazole 1.6 mg / rat / day, nitrite 600 mg / kg / day and omeprazole plus nitrite simultaneously.

Results:

The proliferative lesions found were: squamous hyperplasia - 69.1%, adenomatous hyperplasia in the anastomosis - 29.1% and prepyloric adenomatous hyperplasia - 42.5%. Adenocarcinomas were registered in 7 animals (5.8%): one in Group I (omeprazole plus nitrite), two in Group II (omeprazole and nitrite plus omeprazole) and four in Group III (water, nitrite, omeprazole and omeprazole plus nitrite).

Conclusions:

The occurrence of squamous hyperplasia, adenomatous hyperplasia and adenocarcinoma increased after gastrojejunal anastomoses, which cause duodenogastric reflux. The association of omeprazole did not protect the development of proliferative lesions and cancer induced by duodenogastric reflux in rats.

Three-Dimensional Culture Systems in Gastric Cancer Research

Gastric cancer (GC), which includes cancer of the esophagus, the oesophagogastric junction, and the stomach fundus, is highly deadly with strong regional influence, Asia being the most affected. GC is often detected at late stages, with 30% of metastatic cases at diagnosis. Many authors have devised models to both unravel the mechanisms of GC development and to evaluate candidate therapeutics. Among these models, 2D-cell cultures are progressively replaced by 3D-cell cultures that recapitulate, much more comprehensively, tumor cellular and genetic heterogeneity, as well as responsiveness to environmental changes, such as exposure to drugs or irradiation. With respect to the specifics of GC, there are high hopes from such model systems, especially with the aim of identifying prognostic markers and novel drug targets.

The role of claudin-4 in the development of gastric cancer

Gastric cancer is one of most challenging cancers and a significant cause of death worldwide. Gastric cancer is, associated with a high incidence and recurrence rate of metastatic disease and poor survival for those with metastatic disease. Claudin-4 is a transmembrane protein that plays an important role in tight junctions. Increasing experimental research has demonstrated that claudin-4 plays an important role in the progression of gastric cancer, including the occurrence of epithelial to mesenchymal transition, intestinal metaplasia, and gastric cancer. In addition, claudin-4 regulates cell proliferation, invasion, migration and apoptosis. Claudin-4 may represent a potential biomarker for gastric cancer patient prognosis and is useful in the classification of gastric cancer. Therefore, in this review, we summarize current information on claudin-4 and gastric cancer, describing the role of claudin-4 in gastric cancer progression and its application in clinical treatment to provide a basis for further research and promote the claudin-4 gene as a potential target to diagnose and treat gastric cancer.

Potential proton pump inhibitor-related adverse effects

Proton pump inhibitors (PPIs) are one of the most common medications taken by patients worldwide. PPIs are used to treat acid-related disorders, including gastroesophageal reflux disease, peptic ulcer disease, Helicobacter pylori infection, and nonsteroidal anti-inflammatory drug/stress ulceration. For some of these diseases, long-term treatment is necessary. With such prolonged use, concern and investigation into potential adverse effects has increased. In addition, data are available regarding potential anticancer effects of PPIs, especially regarding solid tumors. The aim of this review is to assess the literature on PPIs with regard to common concerns, such as drug-drug interactions, the intestinal microbiome, dementia and central nervous system disease, and osteoporosis, as well as to highlight potential negative and positive impacts of the drug in cancer.

STAT3 Pathway in Gastric Cancer: Signaling, Therapeutic Targeting and Future Prospects

Molecular signaling pathways play a significant role in the regulation of biological mechanisms, and their abnormal expression can provide the conditions for cancer development. The signal transducer and activator of transcription 3 (STAT3) is a key member of the STAT proteins and its oncogene role in cancer has been shown. STAT3 is able to promote the proliferation and invasion of cancer cells and induces chemoresistance. Different downstream targets of STAT3 have been identified in cancer and it has also been shown that microRNA (miR), long non-coding RNA (lncRNA) and other molecular pathways are able to function as upstream mediators of STAT3 in cancer. In the present review, we focus on the role and regulation of STAT3 in gastric cancer (GC). miRs and lncRNAs are considered as potential upstream mediators of STAT3 and they are able to affect STAT3 expression in exerting their oncogene or onco-suppressor role in GC cells. Anti-tumor compounds suppress the STAT3 signaling pathway to restrict the proliferation and malignant behavior of GC cells. Other molecular pathways, such as sirtuin, stathmin and so on, can act as upstream mediators of STAT3 in GC. Notably, the components of the tumor microenvironment that are capable of targeting STAT3 in GC, such as fibroblasts and macrophages, are discussed in this review. Finally, we demonstrate that STAT3 can target oncogene factors to enhance the proliferation and metastasis of GC cells.

Shp1 in Solid Cancers and Their Therapy

Shp1 is a cytosolic tyrosine phosphatase that regulates a broad range of cellular functions and targets, modulating the flow of information from the cell membrane to the nucleus. While initially studied in the hematopoietic system, research conducted over the past years has expanded our understanding of the biological role of Shp1 to other tissues, proposing it as a novel tumor suppressor gene functionally involved in different hallmarks of cancer. The main mechanism by which Shp1 curbs cancer development and progression is the ability to attenuate and/or terminate signaling pathways controlling cell proliferation, survival, migration, and invasion. Thus, alterations in Shp1 function or expression can contribute to several human diseases, particularly cancer. In cancer cells, Shp1 activity can indeed be affected by mutations or epigenetic silencing that cause failure of Shp1-mediated homeostatic maintenance. This review will discuss the current knowledge of the cellular functions controlled by Shp1 in non-hematopoietic tissues and solid tumors, the mechanisms that regulate Shp1 expression, the role of its mutation/expression status in cancer and its value as potential target for cancer treatment. In addition, we report information gathered from the public available data from The Cancer Genome Atlas (TCGA) database on Shp1 genomic alterations and correlation with survival in solid cancers patients.

Proton Pump Inhibitors Reduce Pancreatic Adenocarcinoma Progression by Selectively Targeting H+, K+-ATPases in Pancreatic Cancer and Stellate Cells

Pancreatic duct cells are equipped with acid/base transporters important for exocrine secretion. Pancreatic ductal adenocarcinoma (PDAC) cells may utilize such transporters to acidify extracellular tumor microenvironment, creating a niche favoring cell proliferation, fibrosis and resistance to chemotherapy-all contributing to the notoriously bad prognosis of this disease. Here, we report that gastric and non-gastric H⁺, K⁺-ATPases (coded by ATP4A and ATP12A) are overexpressed in human and murine pancreatic cancer and that we can target them specifically with proton pump inhibitors (PPIs) and potassium-competitive acid blockers (P-CABs) in in vitro models of PDAC. Focusing on pantoprazole, we show that it significantly reduced human cancer cell proliferation by inhibiting cellular H⁺ extrusion, increasing K⁺ conductance and promoting cyclin D1-dependent cell cycle arrest and preventing STAT3 activation. Pantoprazole also decreased collagen secretion from pancreatic stellate cells. Importantly, in vivo studies show that pantoprazole treatment of tumor-bearing mice reduced tumor size, fibrosis and expression of angiogenic markers. This work provides the first evidence that H⁺, K⁺-ATPases contribute to PDAC progression and that these can be targeted by inhibitors of these pumps, thus proving a promising therapeutic strategy.

IGF2-AS affects the prognosis and metastasis of gastric adenocarcinoma via acting as a ceRNA of miR-503 to regulate SHOX2

Disorder of long non-coding RNAs (LncRNAs) is found in various types of cancers and demonstrated to be associated with tumor occurrence and development. Our study found that lncRNA insulin growth factor 2 antisense (IGF2-AS) is up-regulated in gastric adenocarcinoma (GAC) tissues and correlated with poor prognosis in patients with GAC. Cell counting kit-8 (CCK8), colony formation, wound healing and transwell assays revealed that knockdown of IGF2-AS in BGC823 and SGC7901 cells significantly suppressed cell proliferation, migration and invasion. While, overexpression of IGF2-AS in AGS and MGC803 cells exhibited the opposite effects. RNA-FISH and subcellular fractionation assay found that most IGF2-AS was distributed in the cytoplasm, suggesting that IGF2-AS functioned as a potential ceRNA. RNA binding protein immunoprecipitation (RIP) assays further confirmed this assumption. By informatics prediction and luciferase reporter assay, we found that IGF2-AS functioned as an efficient miR-503 sponge and the level of miR-503 showed an inverse correlation with IGF2-AS. Short stature homeobox 2 (SHOX2) is predicted and verified as a target of miR-503. Moreover, IGF2-AS expression exhibited a negative correlation with miR-503 and a positive correlation with IGF2-AS. Subsequent rescue assay revealed that down-regulation of miR-503 or restoration of SHOX2 canceled IGF2-AS depletion-induced depression in proliferation and motility of BGC823 and SGC7901 cells. Meanwhile, up-regulation of miR-503 or down-regulation of SHOX2 decreased IGF2-AS overexpression induced promotion in proliferation and motility of AGS and MGC803 cells. In vivo tumorigenicity assay showed that knockdown of IGF2-AS significantly reduced tumor volume. Taken together, our results demonstrated that IGF2-AS takes important regulatory parts in GAC development by functioning as a ceRNA to regulate SHOX2 via sponging miR-503.

Interplay between STAT3, Cell Adhesion Molecules and Angiogenesis-Related Parameters in Gastric Carcinoma. Does STAT3 Really Have a Prognostic Value?

Background and objectives: Gastric cancer (GC) is one of the deadliest malignancies, with the underlying pathophysiological mechanisms still not completely understood. In this study, we aimed to investigate the signal transducer and activator of transcription 3 (STAT3) moleculeconnection with the pathological features of GCs, and the expression of cell adhesive molecules (E-cadherin and β-catenin) and angiogenesis-related factors (vascular endothelial growth factor (VEGF), HIF1α, and CD31)). Materials and Methods: This study comprised 136 cases of GCs with data related to the patients’ demographic characteristics (age, gender) and pathological features (tumor location, gross type, Laurens’ type of GC, histological differentiation, invasion depth, lymphovascular invasion and the presence of metastases) which were correlated with STAT3 expression. Additionally, STAT3 expression and the expression of adhesive molecules and angiogenesis-related factors were studied by immunohistochemical methods. Results: The expression of STAT3 was found to be significantly associated with the occurrence of poorly differentiated GCs in the lower portion of the stomach and with the presence of distant metastases. Interestingly, none of the investigated parameters related to cell adhesion or to angiogenesis were found to be related to the expression of STAT3. Conclusions: The lack of significant differences between the studied STAT3 expression and some of the molecules associated with different cancer features might be due to the characteristics of the studied population sample associated with the origin, heterogeneity, and cancer pathophysiological background. Nonetheless, the results of our study suggest that STAT3 could be a useful marker for the presence of distant GC metastases, which further indicates that STAT3 action might involve some other signaling molecules/pathways that warrant further elucidation.

Negative regulators of STAT3 signaling pathway in cancers

STAT3 is the most ubiquitous member of the STAT family and involved in many biological processes, such as cell proliferation, differentiation, and apoptosis. Mounting evidence has revealed that STAT3 is aberrantly activated in many malignant tumors and plays a critical role in cancer progression. STAT3 is usually regarded as an effective molecular target for cancer treatment, and abolishing the STAT3 activity may diminish tumor growth and metastasis. Recent studies have shown that negative regulators of STAT3 signaling such as PIAS, SOCS, and PTP, can effectively retard tumor progression. However, PIAS, SOCS, and PTP have also been reported to correlate with tumor malignancy, and their biological function in tumorigenesis and antitumor therapy are somewhat controversial. In this review, we summarize actual knowledge on the negative regulators of STAT3 in tumors, and focus on the potential role of PIAS, SOCS, and PTP in cancer treatment. Furthermore, we also outline the STAT3 inhibitors that have entered clinical trials. Targeting STAT3 seems to be a promising strategy in cancer therapy.

Proton pump inhibitor: The dual role in gastric cancer

Proton pump inhibitors (PPIs) are one of the most frequently used medications for upper gastrointestinal diseases. However, a number of physicians have raised concern about the serious side effects of long-term use of PPIs, including the development of gastric cancer. Recent epidemiological studies have reported a significant association between long-term PPI intake and the risk of gastric cancer, even after successful Helicobacter pylori eradication. However, the effects of PPIs on the development of pre-malignant conditions such as atrophic gastritis or intestinal metaplasia are not fully known, suggesting the need for comprehensive and confirmative studies are needed in the future. Meanwhile, several experimental studies have demonstrated the effects of PPIs in reducing chemoresistance in gastric cancer cells by modulating the acidic microenvironment, cancer stemness and signal transducer and activator of transcription 3 (STAT3) signaling pathway. The inhibitory effects of PPIs on STAT3 activity may overcome drug resistance and enhance the efficacy of conventional or targeted chemotherapeutic agents. Taken together, PPIs may “play dual role” in gastric carcinogenesis and treatment of gastric cancer.