Reduced expression of PTEN and increased PTEN phosphorylation at residue Ser380 in gastric cancer tissues: a novel mechanism of PTEN inactivation

Evaluation of phosphatase and tensin homologue (PTEN) expression in gastric cancer and its relationship with histopathological findings

INTRODUCTION

Phosphatase and tensin homologue (PTEN) is an important tumour suppressor in multi-step tumorigenesis. To establish the role of PTEN in gastric cancer progression, we examined the PTEN expression degree in gastric cancer tissues. We also explained the connection between PTEN expression and histopathological findings.

MATERIALS AND METHODS

Our study was cross-sectional and made up of 50 patients with known gastric cancer. Immunohistochemical staining for PTEN was done on gastric cancer tissues. Tumour behaviour was estimated by histopathological assessments.

RESULTS

Twenty-seven (54%) of the 50 patients had PTEN staining. The evaluation of the connection between PTEN expression and demographic data and tumour behaviours revealed no meaningful relationship between PTEN expression and patients' age, gender, tumour site and size, tumour type, tumour grade and stage, neural, and lymphovascular invasion (P-value>0.05).

CONCLUSION

PTEN expression level is expected to be a significant molecular event in the progression of gastric cancer and may be a predictive marker for gastric cancer behaviours dependent on society.

Development of a Genetically Engineered Mouse Model Recapitulating LKB1 and PTEN Deficiency in Gastric Cancer Pathogenesis

The LKB1 and PTEN genes are critical in gastric cancer (G.C.) development. LKB1, a robust tumor suppressor gene, encodes a serine/threonine kinase that directly triggers the activation of AMPK-an integral cellular metabolic kinase. The role of the LKB1 pathway extends to maintaining the stability of epithelial junctions by regulating E-cadherin expression. Conversely, PTEN, a frequently mutated tumor suppressor gene in various human cancers, emerges as a pivotal negative regulator of the phosphoinositide 3-kinase (PI3K) signaling pathway. This study is set to leverage the H+/K+ ATPase Cre transgene strain to precisely target Cre recombinase expression at parietal cells within the stomach. This strategic maneuver seeks to selectively nullify the functions of both LKB1 and PTEN in a manner specific to the stomach, thereby instigating the development of G.C. in a fashion akin to human gastric adenocarcinoma. Moreover, this study endeavors to dissect the intricate ways in which these alterations contribute to the histopathologic advancement of gastric tumors, their potential for invasiveness and metastasis, their angiogenesis, and the evolving tumor stromal microenvironment. Our results show that conditional deletion of PTEN and LKB1 provides an ideal cancer microenvironment for G.C. tumorigenesis by promoting cancer cell proliferation, angiogenesis, and metastasis.

Hyperphosphorylated PTEN exerts oncogenic properties

PTEN is a multifaceted tumor suppressor that is highly sensitive to alterations in expression or function. The PTEN C-tail domain, which is rich in phosphorylation sites, has been implicated in PTEN stability, localization, catalytic activity, and protein interactions, but its role in tumorigenesis remains unclear. To address this, we utilized several mouse strains with nonlethal C-tail mutations. Mice homozygous for a deletion that includes S370, S380, T382 and T383 contain low PTEN levels and hyperactive AKT but are not tumor prone. Analysis of mice containing nonphosphorylatable or phosphomimetic versions of S380, a residue hyperphosphorylated in human gastric cancers, reveal that PTEN stability and ability to inhibit PI3K-AKT depends on dynamic phosphorylation-dephosphorylation of this residue. While phosphomimetic S380 drives neoplastic growth in prostate by promoting nuclear accumulation of β-catenin, nonphosphorylatable S380 is not tumorigenic. These data suggest that C-tail hyperphosphorylation creates oncogenic PTEN and is a potential target for anti-cancer therapy.

Looking at Thyroid Cancer from the Tumor-Suppressor Genes Point of View

Thyroid cancer is the most frequent endocrine malignancy and accounts for approximately 1% of all diagnosed cancers. A variety of mechanisms are involved in the transformation of a normal tissue into a malignant one. Loss of tumor-suppressor gene (TSG) function is one of these mechanisms. The normal functions of TSGs include cell proliferation and differentiation control, genomic integrity maintenance, DNA damage repair, and signaling pathway regulation. TSGs are generally classified into three subclasses: (i) gatekeepers that encode proteins involved in cell cycle and apoptosis control; (ii) caretakers that produce proteins implicated in the genomic stability maintenance; and (iii) landscapers that, when mutated, create a suitable environment for malignant cell growth. Several possible mechanisms have been implicated in TSG inactivation. Reviewing the various TSG alteration types detected in thyroid cancers may help researchers to better understand the TSG defects implicated in the development/progression of this cancer type and to find potential targets for prognostic, predictive, diagnostic, and therapeutic purposes. Hence, the main purposes of this review article are to describe the various TSG inactivation mechanisms and alterations in human thyroid cancer, and the current therapeutic options for targeting TSGs in thyroid cancer.

In vitro anti-Helicobacter pylori activity of Syzygium aromaticum and the preliminary mechanism of action

ETHNOPHARMACOLOGICAL RELEVANCE

The dried flower bud of Syzygium aromaticum (L.) Merr. & L.M Perry (S. aromaticum) (Myrtaceae), also known as clove, was used in Traditional Chinese Medicine (TCM) to aid gastrointestinal function and treat stomach disorders including vomiting, flatulence and nausea. And it is a food homology medicine which is a promising candidate for H. pylori treatment. H. pylori is a Gram-negative bacterium that infects approximately 50% of the human population worldwide, which is closely related to multiple gastric diseases, including gastric cancer. However, there are still no sufficient studies on the anti-H. pylori activity of S. aromaticum, especially for the mechanism of action.

AIM OF STUDY

This study aimed to study the antibacterial activities of S. aromaticum extracts on both antibiotic-sensitive and -resistant H. pylori strains, and to explore the underlying mechanisms of action.

MATERIALS AND METHODS

The S. aromaticum extracts were obtained by heat reflux extraction and lyophilized to powder form. The phytochemical analyses were performed by High-performance liquid chromatography (HPLC) and UPLC-electrospray ionization mass spectrometry (ESI-MS). In vitro anti-H. pylori activity was evaluated by broth microdilution method. Mechanism of action studies included morphological observation using electron microscopy, determination of expression of virulence genes by reverse transcription quantitative polymerase chain reaction (RT-qPCR), genes expression profile identification by transcriptomic analysis, and exploration of anti-H. pylori infection mechanisms by network pharmacology analysis and western blotting validation.

RESULTS

The S. aromaticum extracts, aqueous extract (AE) and 75% hydroalcoholic extract (HE), exerted significant antibacterial activities against both antibiotic-sensitive and -resistant H. pylori strains with MICs of 160∼320 μg/ml, without developing drug resistance. Among them, AE was bactericide to all the tested strains with MBCs of less than 4MIC, while HE was merely bacteriostatic to most of the tested strains with MBCs of 2MIC∼16MIC. Besides, they showed no antagonistic effects in combination with clarithromycin, metronidazole, levofloxacin, and amoxicillin. Additionally, these extracts altered the morphology and ultrastructure and down-regulated the virulence genes expression of H. pylori. And transcriptomic analysis showed that they regulated genes expression of multiple H. pylori biological processes, including tricarboxylic acid cycle (TAC) and pyruvate metabolic pathways. Furthermore, these extracts combated the abnormal activation of PI3K-Akt and MAPK signaling pathways caused by H. pylori infection.

CONCLUSIONS

Overall, the present study firstly analyzed the chemical compositions of S. aromaticum extracts, and then confirmed their activities on both antibiotic-sensitive and -resistant H. pylori strains. In addition, the mechanisms of action of S. aromaticum extracts against H. pylori were found to be destroying the bacterial structure, down-regulating the expression of virulence genes, and interfering TAC and pyruvate metabolic pathways. Finally, S. aromaticum extracts were found to combated the abnormal activation of PI3K-Akt and MAPK signaling pathways to treat H. pylori infection. This study should accelerate further research and application of S. aromaticum against H. pylori infection.

Integrative Analysis of Deregulated miRNAs Reveals Candidate Molecular Mechanisms Linking H. pylori Infected Peptic Ulcer Disease with Periodontitis

OBJECTIVE

Periodontitis is a highly prevalent oral infectious disease and has been increasingly associated with H. pylori infection, gastric inflammation, and gastric cancer but little is known about epigenetic machinery underlying this potentially bidirectional association. The present study is aimed at identifying key deregulated miRNA, their associated genes, signaling pathways, and compounds linking periodontitis with H. pylori-associated peptic ulcer disease.

METHODS

miRNA expression datasets for periodontitis-affected and H. pylori-associated peptic ulcer disease-affected tissues were sought from the GEO database. Differentially expressed miRNA (DEmiRNAs) were identified and the overlapping, shared-DEmiRNA between both datasets were determined. Shared-DEmiRNA-target networks construction and functional analyses were constructed using miRNet 2.0, including shared-DEmiRNA-gene, shared-DEmiRNA-transcription factor (TF), and shared-DEmiRNA-compound networks. Functional enrichment analysis for shared DEmiRNA-gene and shared DEmiRNA-TF networks was performed using the KEGG, Reactome, and Geno Ontology (GO) pathways.

RESULTS

11 shared-DEmiRNAs were identified, among which 9 showed similar expression patterns in both diseases, and 7 were overexpressed. miRNA hsa-hsa-mir-155-5p and hsa-mir-29a-3p were top miRNA nodes in both gene and TF networks. The topmost candidate miRNA-deregulated genes were PTEN, CCND1, MDM2, TNRC6A, and SCD while topmost deregulated TFs included STAT3, HIF1A, EZH2, CEBPA, and RUNX1. Curcumin, 5-fluorouracil, and the gallotanin 1,2,6-Tri-O-galloyl-beta-D-glucopyranose emerged as the most relevant linkage compound targets. Functional analyses revealed multiple cancer-associated pathways, PI3K pathways, kinase binding, and transcription factor binding among as enriched by the network-associated genes and TFs.

CONCLUSION

Integrative analysis of deregulated miRNAs revealed candidate molecular mechanisms comprising of top miRNA, their gene, and TF targets linking H. pylori-infected peptic ulcer disease with periodontitis and highlighted compounds targeting both diseases. These findings provide basis for directing future experimental research.

Upregulation of oncogene Activin A receptor type I by Helicobacter pylori infection promotes gastric intestinal metaplasia via regulating CDX2

BACKGROUND

Activin A receptor type I (ACVR1) is involved in tumorigenesis. However, the underlying molecular mechanisms of ACVR1 in gastric cancer (GC) and its association with Helicobacter pylori remained unclear.

MATERIALS AND METHODS

The Cancer Genome Atlas (TCGA) and Gene Expression Profiling Interactive Analysis (GEPIA) database were utilized to explore the ACVR1 expression in GC and normal control and its association with survival. The ACVR1 was knocked out using CRISPR/Cas-9; RNA sequencing analysis was performed in AGS cells with ACVR1 knockout and normal control. Functional experiments (CCK-8, colony-forming, and transwell assays) were conducted to demonstrate the role of ACVR1 in cell proliferation, invasion, and metastasis. H. pylori-infected C57/BL6 models were established. ACVR1, p-Smad1/5, and CDX2 were detected in AGS cells cocultured with H. pylori strains. The CDX2 and key elements of BMP signaling pathway were detected in AGS cells with ACVR1 knockout and normal control. In addition, Immunohistochemistry was performed to detect the ACVR1 and CDX2 expression in gastric samples.

RESULTS

ACVR1 expression was higher in GC than normal control from TCGA, GEPIA, and samples collected from our hospital (p < 0.05). ACVR1 promoted cell proliferation, migration, and invasion in vitro. Both cagA⁺ and cagA^- H. pylori could upregulate the expression ACVR1 (p < 0.05). Downregulation of ACVR1 inhibited the H. pylori-induced cell proliferation, migration, and invasion (p < 0.05). H. pylori increased the expression of p-Smad 1/5 and CDX2. The CDX2 and key elements of BMP signaling pathway were downregulated in AGS cells with ACVR1 knockout. ACVR1 and CDX2 were upregulated in the stage of intestinal metaplasia (IM). Moreover, ACVR1 and CDX2 expressions were higher in H. pylori-positive group than H. pylori-negative group (p < 0.05).

CONCLUSION

Our data indicate that H. pylori infection increases ACVR1 expression, promoting gastric IM via regulating CDX2, which is an essential step in H. pylori carcinogenesis.

MicroRNA-223-5p suppresses the progression of nasopharyngeal carcinoma by targeting DCLK1

The aim of the present study was to investigate the function of microRNA (miR)-223-5p in the malignant biological behavior of nasopharyngeal carcinoma (NPC) and elucidate the underlying molecular mechanism. The expression levels of miR-223-5p and doublecortin-like kinase 1 (DCLK1) were detected via reverse transcription-quantitative PCR analysis. Cell viability was evaluated using Cell Counting Kit-8 assay. Cell migration and invasion were measured via Transwell assays, while a luciferase reporter assay was conducted to identify the interaction between miR-223-5p and DCLK1. The results demonstrated that miR-223-5p expression was significantly downregulated, whereas DCLK1 expression was significantly upregulated in NPC tissues and cells. Moreover, both miR-223-5p overexpression and DCLK1 silencing markedly suppressed the progression of NPC. It was also observed that miR-223-5p directly targeted DCLK1 and decreased its expression. Furthermore, it was suggested that DCLK1 overexpression may partially reverse the suppressive effects of miR-223-5p on the progression of NPC. Collectively, the results of the present study indicated that miR-223-5p may suppress NPC progression by targeting DCLK1, thereby indicating a novel potential approach to the diagnosis and treatment of NPC.

MCPIP1 expression positively correlates with melanoma-specific survival of patients, and its overexpression affects vital intracellular pathways of human melanoma cells

The suppressive activity of monocyte chemoattractant protein 1-induced protein 1 (MCPIP1) an inflammation-related ribonuclease, has been described in a few cancer types but has yet to be assessed in the most common subtype of skin cancer: melanoma. Here, we have evaluated the MCPIP1 expression in melanoma tissues by reanalysis of publicly available transcriptome data from 89 melanoma samples, and immunohistochemical staining of 21 primary and 81 metastatic melanomas. Our data implicated decreased MCPIP1 expression in melanoma tumors compared to normal tissues, and positive correlation between high ribonuclease expression and melanoma-specific survival of patients. To investigate the ribonuclease activity in melanoma cells, MCPIP1 was ectopically expressed in the MV3 human melanoma cell line. Following the transcriptome, proteome, and intracellular signaling of MCPIP1-overexpressing MV3 cells was assessed via real-time quantitative polymerase chain reaction, Western blot analysis, and RNAseq. MV3 cells overexpressing MCPIP1 exhibited a broad range of alterations in the transcriptome and proteome, as well as in the phosphorylation status of a number of proteins, strongly indicating MCPIP1-dependent cell cycle arrest and inhibition of Akt/mTOR signaling in these cells. Moreover, we have shown, that MCPIP1 overexpression downregulates miRNA-193a-3p expression in MV3 cells. Furthermore, the majority of the described effects were dependent on the ribonucleolytic activity of the protein. The presented body of data strongly suggests a potential tumor suppressor role and possible future application as a positive prognostic marker of MCPIP1 protein in melanoma.

Helicobacter pylori induces epithelial-mesenchymal transition in gastric carcinogenesis via the AKT/GSK3β signaling pathway

Helicobacter pylori (H. pylori) is a main risk factor for gastric cancer (GC). Epithelial-mesenchymal transition (EMT) is involved in the development and progression of H. pylori-associated GC. However, the exact molecular mechanism of this process remains unclear. The AKT/GSK3β signaling pathway has been demonstrated to promote EMT in several types of cancer. The present study investigated whether H. pylori infection induced EMT, and promoted the development and metastasis of cancer in the normal gastric mucosa, and whether this process was dependent on AKT activation. The expression levels of the EMT-associated proteins, including E-cadherin and N-cadherin, were determined in 165 gastric mucosal samples of different disease stages by immunohistochemical analysis. The expression levels of E-cadherin, N-cadherin, AKT, phosphorylated (p-)AKT (Ser473), GSK3β and p-GSK3β (Ser9) were further determined in H. pylori-infected Mongolian gerbil gastric tissues and cells co-cultured with H. pylori by immunohistochemical analysis and western blotting. The results indicated that the expression levels of the epithelial marker E-cadherin were decreased, whereas the expression levels of the mesenchymal marker N-cadherin were increased during gastric carcinogenesis. Their expression levels were associated with H. pylori infection. Furthermore, H. pylori infection resulted in downregulation of E-cadherin expression and upregulation of N-cadherin expression in Mongolian gerbils and GES-1 cells. In addition, an investigation of the associated mechanism of action revealed that p-AKT (Ser473) and p-GSK3β (Ser9) were activated in GES-1 cells following co-culture with H. pylori. Furthermore, following pretreatment of the cells with the AKT inhibitor VIII, the expression levels of E-cadherin, N-cadherin, p-AKT and p-GSK3β did not show significant differences between GES-1 cells that were co-cultured with or without H. pylori. The levels of p-AKT and p-GSK3β were increased in H. pylori-infected Mongolian gerbils. In conclusion, the present study demonstrated that H. pylori infection activated AKT and resulted in the phosphorylation and inactivation of GSK3β, which in turn promoted early stage EMT. These effects were AKT-dependent. This mechanism may serve as a prerequisite for GC development.

MicroRNA‑28 promotes the proliferation of non‑small‑cell lung cancer cells by targeting PTEN

Non-small-cell lung cancer (NSCLC) is the fundamental form of lung cancer and the leading cause of cancer‑related mortality in humans. Numerous studies have identified a role for microRNAs (miRs) in cell proliferation, invasion and metastasis in numerous types of cancer, including lung cancer. In the present study, the functional roles and molecular mechanisms of miR‑28 in NSCLC tumorigenesis were investigated. Reverse transcription‑quantitative PCR (RT‑qPCR) was used to measure miR‑28 expression levels in NSCLC tumor tissues and cell lines. A dual‑luciferase assay was performed to observe the direct interaction between miR‑28 and PTEN in A549 cells. Furthermore, the effect of miR‑28 on the mRNA and protein expression levels of PTEN was examined by RT‑qPCR and western blotting, respectively. A Cell Counting kit‑8 assay was performed to identify the relationship between the miR‑28/PTEN axis and tumor cell proliferation using cells infected with lentivirus (LV)‑anti‑miR‑28 or LV‑anti‑miR‑28 + short hairpin RNA‑PTEN. miR‑28 expression was upregulated in NSCLC tumor tissues and cell lines compared with the control groups. PTEN was identified as the downstream gene of miR‑28 in NSCLC and was negatively regulated by miR‑28. In addition, miR‑28 knockdown suppressed the proliferation of A549 and H292 cells. Cells infected with LV‑anti‑miR‑28 + short hairpin RNA‑PTEN promoted tumor cell proliferation in A549 and H292 cells compared with cells infected with LV‑anti‑miR‑28. Taken together, the present study suggested that miR‑28 might serve as the promoter in the development of NSCLC by targeting PTEN. Therefore, the miR‑28/PTEN axis may serve as a potential diagnostic and therapeutic target for NSCLC.

A lucid review of Helicobacter pylori-induced DNA damage in gastric cancer

Helicobacter pylori (H pylori) is the main risk factor for gastric cancer (GC). In recent years, many studies have addressed the effects of H pylori itself and of H pylori-induced chronic inflammation on DNA damage. Unrepaired or inappropriately repaired DNA damage is one possible carcinogenic mechanism. We may conclude that H pylori-induced DNA damage is one of the carcinogenic mechanisms of GC. In this review, we summarize the interactions between H pylori and DNA damage and the effects of H pylori-induced DNA damage on GC. Then, focusing on oxidative stress, we introduce the application of antioxidants in GC. At the end of this review, we discuss the outlook for further research on H pylori-induced DNA damage.

Downregulation of tumor suppressor RACK1 by Helicobacter pylori infection promotes gastric carcinogenesis through the integrin β-1/NF-κB signaling pathway

Receptor of activated protein kinase C 1 (RACK1) is downregulated in gastric cancer and is involved in modulating NF-κB signaling pathway activity. However, the underlying molecular mechanisms regulating RACK1 expression are unclear. In this study, we demonstrated that downregulated expression of RACK1 was observed in gastric cancer tissue compared to adjacent normal tissue and was correlated with poor prognosis in patients. Helicobacter pylori (H. pylori) infection downregulated RACK1 expression in concert with canonical NF-κB signaling pathway activation in vivo and in vitro. RACK1 overexpression suppressed NF-κB signaling pathway activation as well as the release of downstream proinflammatory cytokines. In addition, RACK1 downregulation increased integrin β-1 expression, while integrin β-1 silencing decreased NF-κB signaling activation. Moreover, H. pylori infection downregulated RACK1 but upregulated integrin β-1 expression at the precancerous lesion stages in human subjects. Our data indicate that H. pylori infection promotes the upregulation of integrin β-1 expression via downregulation of RACK1 expression, which subsequently leads to the elevated activation of the NF-κB signaling pathway, an essential step in H. pylori-induced carcinogenesis.

Proteomic analysis discovers the differential expression of novel proteins and phosphoproteins in meningioma including NEK9, HK2 and SET and deregulation of RNA metabolism

Background

Meningioma is the most frequent primary intracranial tumour. Surgical resection remains the main therapeutic option as pharmacological intervention is hampered by poor knowledge of their proteomic signature. There is an urgent need to identify new therapeutic targets and biomarkers of meningioma.

Methods

We performed proteomic profiling of grade I, II and III frozen meningioma specimens and three normal healthy human meninges using LC-MS/MS to analyse global proteins, enriched phosphoproteins and phosphopeptides. Differential expression and functional annotation of proteins was completed using Perseus, IPA® and DAVID. We validated differential expression of proteins and phosphoproteins by Western blot on a meningioma validation set and by immunohistochemistry.

Findings

We quantified 3888 proteins and 3074 phosphoproteins across all meningioma grades and normal meninges. Bioinformatics analysis revealed commonly upregulated proteins and phosphoproteins to be enriched in Gene Ontology terms associated with RNA metabolism. Validation studies confirmed significant overexpression of proteins such as EGFR and CKAP4 across all grades, as well as the aberrant activation of the downstream PI3K/AKT pathway, which seems differential between grades. Further, we validated upregulation of the total and activated phosphorylated form of the NIMA-related kinase, NEK9, involved in mitotic progression. Novel proteins identified and validated in meningioma included the nuclear proto-oncogene SET, the splicing factor SF2/ASF and the higher-grade specific protein, HK2, involved in cellular metabolism.

Interpretation

Overall, we generated a proteomic thesaurus of meningiomas for the identification of potential biomarkers and therapeutic targets.

Fund

This study was supported by Brain Tumour Research.

Helicobacter pylori promotes gastric epithelial cell survival through the PLK1/PI3K/Akt pathway

Purpose

Helicobacter pylori (H. pylori) infection plays a critical role in the process of gastric carcinogenesis. However, the complicated pathogenic mechanism is still unclear. Polo-like kinase 1 (PLK1) is involved in the development of multiple human malignancies, including gastric cancer. Therefore, this study aimed to elucidate the role of PLK1 in H. pylori-induced gastric carcinogenesis and the underlying signaling mechanism.

Materials and methods

We detected the expression of PLK1 in 166 patients in different stages of gastric carcinogenesis as well as the established Mongolian gerbil model with H. pylori infection by immunohistochemistry. Cell Counting Kit-8 was used to estimate the survival of gastric cancer cells.

Results

We found that PLK1 expression in gastric cancer tissues was significantly higher than that of paired adjacent mucosa. PLK1 expression was increased in intestinal metaplasia, dysplasia, and gastric cancer tissues compared to chronic non-atrophic gastritis tissues. Notably, PLK1 expression was much lower in H. pylori-negative tissues than in H. pylori-positive tissues at intestinal metaplasia stage. In addition, H. pylori infection increased PLK1 expression in the gastric epithelial cells of the Mongolian gerbil model, which was positively related to the duration of H. pylori infection. Inhibition of PLK1 significantly reduced H. pylori-induced cell proliferation. Furthermore, incubation of MKN-28 cells with H. pylori resulted in a significant increase in PLK1, p-PTEN, and the downstream PI3K/Akt pathway, and pretreatment with a PLK1 inhibitor reversed these molecular changes.

Conclusion

PLK1 is involved in H. pylori-induced gastric carcinogenesis at the early stage by activating the PI3K/Akt signaling pathway. These results may contribute to the development of new control strategies for H. pylori infection-related gastric cancer.

PTEN lipid phosphatase inactivation links the hippo and PI3K/Akt pathways to induce gastric tumorigenesis

Background

Phosphatase and tensin homolog (PTEN) is an important tumor suppressor gene, and its encoded protein has activities of both a protein phosphatase and a lipid phosphatase. However, the substitution effect of protein phosphatase activity remains unclear. PI3K/Akt is the most common pathway negatively regulated by PTEN. The Hippo and PI3K/Akt pathways have a joint effect in regulating cell proliferation and apoptosis. Therefore, how PTEN lipid phosphatase inactivation contributes to the occurrence and development of gastric cancer and the potential role of the Hippo and PI3K/Akt pathways in PTEN lipid phosphatase inactivation mediated gastric tumorigenesis remain to be explored.

Methods

Immunohistochemical staining was performed to detect the expression of p-PTEN and YAP in a gastric cancer tissue microarray. Stable cell lines expressing a wild-type or dominant-negative mutant PTEN were established. The proliferation and migration of stable cells were detected by MTT, BrdU, and colony-formation, transwell assay and high content analysis in vitro, and tumor growth differences were observed in xenograft nude mice. Changes in the expression of key molecules in the Hippo and Akt signaling pathways were detected by western blot. Nuclear-cytoplasm separation, immunofluorescence and coimmunoprecipitation analyses were conducted to explore the dysregulation of Hippo in the stable cell lines.

Results

PTEN lipid phosphatase inactivation strongly promoted the proliferation and migration of gastric cancer cells in vitro and tumor growth in vivo. A immunohistochemical analysis of gastric cancer tissues revealed a significant correlation between phosphorylated PTEN and nuclear YAP expression, and both were determined to be independent prognostic factors for gastric cancer. Mechanistically, PTEN lipid phosphatase inactivation abolished the MOB1-LATS1/2 interaction, decreased YAP phosphorylation and finally promoted YAP nuclear translocation, which enhanced the synergistic effect of YAP-TEAD, thus inducing cell proliferation and migration. Moreover, PTEN lipid phosphatase inactivation promoted the PI3K/Akt pathway, and disruption of YAP-TEAD-driven transcription decreased the activation of Akt in a dose-dependent manner.

Conclusions

Taken together, our findings indicate that PTEN lipid phosphatase inactivation links the Hippo and PI3K/Akt pathways to promote gastric tumorigenesis and cancer development.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0795-2) contains supplementary material, which is available to authorized users.

PTEN Physically Interacts with and Regulates E2F1-mediated Transcription in Lung Cancer

PTEN phosphorylation at its C-terminal (C-tail) serine/threonine cluster negatively regulates its tumor suppressor function. However, the consequence of such inhibition and its downstream effects in driving lung cancer remain unexplored. Herein, we ascertain the molecular mechanisms by which phosphorylation compromises PTEN function, contributing to lung cancer. Replacement of the serine/threonine residues with alanine generated PTEN-4A, a phosphorylation-deficient PTEN mutant, which suppressed lung cancer cell proliferation and migration. PTEN-4A preferentially localized to the nucleus where it suppressed E2F1-mediated transcription of cell cycle genes. PTEN-4A physically interacted with the transcription factor E2F1 and associated with chromatin at gene promoters with E2F1 DNA-binding sites, a likely mechanism for its transcriptional suppression function. Deletion analysis revealed that the C2 domain of PTEN was indispensable for suppression of E2F1-mediated transcription. Further, we uncovered cancer-associated C2 domain mutant proteins that had lost their ability to suppress E2F1-mediated transcription, supporting the concept that these mutations are oncogenic in patients. Consistent with these findings, we observed increased PTEN phosphorylation and reduced nuclear PTEN levels in lung cancer patient samples establishing phosphorylation as a bona fide inactivation mechanism for PTEN in lung cancer. Thus, use of small molecule inhibitors that hinder PTEN phosphorylation is a plausible approach to activate PTEN function in the treatment of lung cancer. Abbreviations AKT V-Akt Murine Thymoma Viral Oncogene CA Cancer adjacent CDK1 Cyclin dependent kinase 1 CENPC-C Centromere Protein C ChIP Chromatin Immunoprecipitation co-IP Co-immunoprecipitation COSMIC Catalog of Somatic Mutations In Cancer CREB cAMP Responsive Element Binding Protein C-tail Carboxy terminal tail E2F1 E2F Transcription Factor 1 ECIS Electric Cell-substrate Impedance Sensing EGFR Epidermal Growth Factor Receptor GSI Gamma Secretase Inhibitor HDAC1 Histone Deacetylase 1 HP1 Heterochromatin protein 1 KAP1/TRIM28 KRAB-Associated Protein 1/Tripartite Motif Containing 28 MAF1 Repressor of RNA polymerase III transcription MAF1 homolog MCM2 Minichromosome Maintenance Complex Component 2 miRNA micro RNA MTF1 Metal-Regulatory Transcription Factor 1 PARP Poly(ADP-Ribose) Polymerase PD-1 Programmed Cell Death 1 PD-L1 Programmed Cell Death 1 Ligand 1 PI3K Phosphatidylinositol-4,5-Bisphosphate 3-Kinase PLK Polo-like Kinase pPTEN Phosphorylated PTEN PTEN Phosphatase and Tensin Homolog deleted on chromosome ten PTM Post Translational Modification Rad51 RAD51 Recombinase Rad52 RAD52 Recombinase RPA1 Replication protein A SILAC Stable Isotope Labeling with Amino Acids in Cell Culture SRF Serum Response Factor TKI Tyrosine Kinase inhbitors TMA Tissue Microarray TOP2A DNA Topoisomerase 2A.

N-Acetylcysteine Reduces ROS-Mediated Oxidative DNA Damage and PI3K/Akt Pathway Activation Induced by Helicobacter pylori Infection

Background

H. pylori infection induces reactive oxygen species- (ROS-) related DNA damage and activates the PI3K/Akt pathway in gastric epithelial cells. N-Acetylcysteine (NAC) is known as an inhibitor of ROS; the role of NAC in H. pylori-related diseases is unclear.

Aim

The aim of this study was to evaluate the role of ROS and the protective role of NAC in the pathogenesis of H. pylori-related diseases.

Method

An in vitro coculture system and an in vivo Balb/c mouse model of H. pylori-infected gastric epithelial cells were established. The effects of H. pylori infection on DNA damage and ROS were assessed by the comet assay and fluorescent dichlorofluorescein assay. The level of PI3K/Akt pathway-related proteins was evaluated by Western blotting. The protective role of N-acetylcysteine (NAC) was also evaluated with in vitro and in vivo H. pylori infection models.

Results

The results revealed that, in vitro and in vivo, H. pylori infection increased the ROS level and induced DNA damage in gastric epithelial cells. NAC treatment effectively reduced the ROS level and inhibited DNA damage in GES-1 cells and the gastric mucosa of Balb/c mice. H. pylori infection induced ROS-mediated PI3K/Akt pathway activation, and NAC treatment inhibited this effect. However, the gastric mucosa pathological score of the NAC-treated group was not significantly different from that of the untreated group. Furthermore, chronic H. pylori infection decreased APE-1 expression in the gastric mucosa of Balb/c mice.

Conclusions

An increased ROS level is a critical mechanism in H. pylori pathogenesis, and NAC may be beneficial for the treatment of H. pylori-related gastric diseases linked to oxidative DNA damage.

MicroRNA-21 promotes TGF-β1-induced epithelial-mesenchymal transition in gastric cancer through up-regulating PTEN expression

This study aimed to explore the effects of miR-21 and PTEN/Akt signaling pathway on TGF-β1-induced epithelial-mesenchymal transition (EMT) in gastric cancer (GC). GC tissues and adjacent tissues were collected from 83 patients. The qRT-PCR assay was performed to detect miR-21 expression. The expressions of PTEN, Akt and p-Akt were detected by immunohistochemistry. After 48 h of treatment with TGF-β1 (10 ng/mL), the SGC-7901 and KATO-III cells were divided into the blank, negative control (NC), miR-21 inhibitors, PTEN-siRNA and miR-21 inhibitors + PTEN-siRNA groups. EMT related factors and PTEN expressions were detected by qRT-PCR assay and Western blotting. The scratch test was conducted to observe cell migration. Xenograft tumor model in nude mice was used to evaluate the effects of miR-21 on EMT of GC cells in vivo. In GC tissues, the expressions of miR-21, Akt and p-Akt were up-regulated, while PTEN expression was down-regulated. Gene and protein expressions of E-cadherin and PTEN in the miR-21 inhibitors group were higher than the blank, NC, PTEN-siRNA and miR-21 inhibitors + PTEN-siRNA groups, while the expressions of N-cadherin, β-catenin, Vimentin and Slug in the miR-21 inhibitors group were lower than other groups. MiR-21 inhibitors significantly inhibit cell migration and invasion in GC cell lines. In vivo xenograft experiment revealed that miR-21 inhibitor inhibits the growth of transplanted tumor through up-regulating E-cadherin and PTEN expressions and down-regulating the expressions of N-cadherin, β-catenin, Vimentin and Slug. These results suggest that miR-21 could promote TGF-β1-induced EMT in GC cells through up-regulating PTEN expression.

YMO1 suppresses invasion and metastasis by inhibiting RhoC signaling and predicts favorable prognosis in hepatocellular carcinoma

Previous studies have shown that 4.1 proteins, which are deregulated in many cancers, contribute to cell adhesion and motility. Yurt/Mosaic eyes-like 1 (YMO1) is a member of 4.1 protein family but it is unclear whether YMO1 plays a role in tumor invasion. This study aimed to investigate the effects of YMO1 on hepatocellular carcinoma (HCC) and attempted to elucidate the underlying molecular mechanisms. YMO1 expression in HCC tissues and its correlation with clinicopathological features and postoperative prognosis was analyzed. The results showed that YMO1 was down-regulated in the highly metastatic HCC cell line and in human tumor tissues. Underexpression of YMO1 indicated poor prognosis of HCC patients. Restoration of YMO1 expression caused a significant decrease in cell migration and invasiveness in vitro. In vivo study showed that YMO1 reduced liver tumor invasion and metastasis in xenograft mice. YMO1 directly inhibited RhoC activation. YMO1 expression in HCC was regulated by PAX5. Analysis of YMO1 expression levels in human HCC patients revealed a significant correlation of YMO1 expression with PAX5 and RhoC. Our findings revealed that YMO1 predicts favorable prognosis and the data suggest that YMO1 suppresses tumor invasion and metastasis by inhibiting RhoC activity.

Phosphorylation of phosphatase and tensin homolog induced by Helicobacter pylori promotes cell invasion by activation of focal adhesion kinase

Phosphorylation of the phosphatase and tensin homolog (PTEN) tumor suppressor at Ser380/Thr382/Thr383 residues is a novel mechanism underlying PTEN inactivation in gastric carcinogenesis, which may be triggered by Helicobacter pylori infection. To investigate this further, the effect of H. pylori infection on PTEN phosphorylation and the subsequent activation of focal adhesion kinase (FAK), were evaluated in gastric tissue samples from Mongolian gerbils and in the human gastric epithelial mucosa cell line GES-1 using immunohistochemistry, western blotting and Transwell assays. The in vivo and in vitro results of the present study demonstrated that H. pylori infection induced the phosphorylation and inactivation of PTEN at Ser380/Thr382/383, and the subsequent phosphorylation and activation of FAK at Tyr397. Gastric epithelial cell invasion was also increased. Furthermore, stable expression of a dominant-negative PTEN mutant inhibited the enhanced FAK activation and cell invasion induced by H. pylori infection. These results suggest that the mechanism underlying H. pylori-induced carcinogenesis may involve promoting cell invasion through the phosphorylation of PTEN and the activation of FAK.

Comprehensive genomic analysis of Oesophageal Squamous Cell Carcinoma reveals clinical relevance

Oesophageal carcinoma is the fourth leading cause of cancer-related death in China, and more than 90% of these tumours are oesophageal squamous cell carcinoma (ESCC). Although several ESCC genomic sequencing studies have identified mutated somatic genes, the number of samples in each study was relatively small, and the molecular basis of ESCC has not been fully elucidated. Here, we performed an integrated analysis of 490 tumours by combining the genomic data from 7 previous ESCC projects. We identified 18 significantly mutated genes (SMGs). PTEN, DCDC1 and CUL3 were first reported as SMGs in ESCC. Notably, the AJUBA mutations and mutational signature4 were significantly correlated with a poorer survival in patients with ESCC. Hierarchical clustering analysis of the copy number alteration (CNA) of cancer gene census (CGC) genes in ESCC patients revealed three subtypes, and subtype3 exhibited more CNAs and marked for worse prognosis compared with subtype2. Moreover, database annotation suggested that two significantly differential CNA genes (PIK3CA and FBXW7) between subtype3 and subtype2 may serve as therapeutic drug targets. This study has extended our knowledge of the genetic basis of ESCC and shed some light into the clinical relevance, which would help improve the therapy and prognosis of ESCC patients.

Aberrant Akt Activation During Implantation Window in Infertile Women With Intramural Uterine Fibroids

The objective of the study was to examine the expression and cellular distribution of key signaling components of the phosphatidylinositol-3-kinase (PI3K)/Phosphatase and Tensin Homolog Deleted on Chromosome Ten (PTEN)/Protein Kinase B (PKB/Akt) pathway during the window of implantation in infertile women with noncavity-distorting intramural uterine fibroids (n = 21) as compared to fertile controls (n = 15). Relative gene expression analysis of PIK3CA, PTEN, Akt1, and Akt2 genes in midluteal endometrial biopsies was performed by real-time polymerase chain reaction. Immunohistochemistry was used to evaluate the expression of PIK3CA, PTEN, phospho-PTEN, Akt1, Akt2, phospho-Akt1 (serine 473), phospho-Akt1 (threonine 308), and Ki67 proteins. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling assay was performed for apoptosis detection. In comparison to fertile controls, significant upregulation of Akt1 messenger RNA levels (2.16-fold; P < .05); cell-specific upregulation of the proteins phospho-PTEN ( P < .05), Akt1 ( P < .05), Akt2 ( P < .05), and p-Akt (S473; P < .001); and downregulation of PTEN ( P < .01) were observed in endometrium of infertile women with intramural fibroids. The ratio of p-PTEN/PTEN and p-Akt1 (S473)/Akt1 was also significantly higher in infertile women. Increased Ki67 labeling index in the glandular epithelium and significantly lower apoptotic index in glandular epithelium and stroma were seen in infertile women during the window of implantation. Aberrant Akt activation and the associated imbalance in endometrial proliferation and apoptosis observed in infertile women with intramural fibroids during the midsecretory phase might contribute to impaired endometrial receptivity leading to infertility in these patients.

PDZ-containing 1 acts as a suppressor of pancreatic cancer by regulating PTEN phosphorylation

Phosphorylation is a recently established cause of phosphatase and tensin homolog (PTEN) gene inactivation, which leads to defect tumour-suppressor function. In pancreatic cancer, this phenomenon has not been reported. Based on database and clinical sample analyses, we found that PTEN phosphorylation occurs in pancreatic ductal adenocarcinoma patient tissues and cell lines, and we aimed to find a method for dephosphorylation. PDZ-containing 1 (PDZK1), a tumour-associated protein that shares its PDZ-binding sequence with the carboxyl-terminal domain of PTEN, was significantly down-regulated in pancreatic cancer as compared to adjacent non-tumour tissues. In vitro, PDZK1 overexpression reversed the proliferation and migration abilities of pancreatic cancer cells and led to significantly decreased PTEN phosphorylation and AKT phosphorylation by interacting with wild-type PTEN. In addition, a transcription factor-activation assay supported that PDZK1 overexpression enhanced the anti-oncogene function of PTEN by regulating the activities of its downstream transcription factors, including p53, NF-κB, and FOXO1. In vivo, nude mice stably over-expressing PDZK1 had lower tumour weights and volumes and showed significantly down-regulated PTEN phosphorylation in xenograft tumour tissues as compared to the control group. Moreover, low PDZK1 expression strongly correlated with advanced stage and poor prognosis of patients with pancreatic ductal adenocarcinoma. In conclusion, our study elucidated the tumour-suppressor role of PDZK1 in pancreatic cancer through down-regulating PTEN phosphorylation, and established PDZK1 as a potential novel prognostic marker for pancreatic cancer.

Mechanism of apoptosis involved in gastric mucosal lesions in Tibetans with high-altitude polycythemia

The Tibetan high plateau is a low-oxygen environment, which may cause the pathogenesis of high-altitude polycythemia (HAPC). Gastric mucosal lesions (GML) are a common complication of HAPC. The molecular mechanisms involved in HAPC-induced GML have remained to be fully elucidated and were therefore investigated in the present study. Gastric tissues of patients with heavy, HAPC-induced GML and healthy controls were assessed by ultrastructural and histopathological analysis. In addition, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling and reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis were used to detect cell apoptosis in the gastric mucosa tissues. Moreover, the expression of genes associated with the phosphoinositide-3 kinase (PI3K) pathway was assessed by RT-qPCR to investigate the mechanism of cell apoptosis in HAPC-induced GML. The results revealed a significant increase in the number of red blood cells, gastric vessels and the diameter of gastric mucosal vessels in HAPC-induced GML patients compared with those in healthy controls. In addition, more red blood cells were distributed in gastric tissue not only at the vascular level but also in the tissue space. The number of vacuoles was increased in the gastric mucosal cells. Furthermore, a significant increase in apoptosis of the gastric mucosal cells was identified. The expression of phosphatase and tensin homolog was significantly higher in gastric mucosa from patients with HAPC-induced GML compared with that in the healthy controls. All of the pathologic changes suggested that significant cell apoptosis occurred in the HAPC-induced GML tissues, which may be associated with the PI3K pathway. These findings may provide novel insight for the treatment of gastric lesions caused by HAPC in the future.

PTEN proteoforms in biology and disease

Proteoforms are specific molecular forms of protein products arising from a single gene that possess different structures and different functions. Therefore, a single gene can produce a large repertoire of proteoforms by means of allelic variations (mutations, indels, SNPs), alternative splicing and other pre-translational mechanisms, post-translational modifications (PTMs), conformational dynamics, and functioning. Resulting proteoforms that have different sizes, alternative splicing patterns, sets of post-translational modifications, protein-protein interactions, and protein-ligand interactions, might dramatically increase the functionality of the encoded protein. Herein, we have interrogated the tumor suppressor PTEN for its proteoforms and find that this protein exists in multiple forms with distinct functions and sub-cellular localizations. Furthermore, the levels of each PTEN proteoform in a given cell may affect its biological function. Indeed, the paradigm of the continuum model of tumor suppression by PTEN can be better explained by the presence of a continuum of PTEN proteoforms, diversity, and levels of which are associated with pathological outcomes than simply by the different roles of mutations in the PTEN gene. Consequently, understanding the mechanisms underlying the dysregulation of PTEN proteoforms by several genomic and non-genomic mechanisms in cancer and other diseases is imperative. We have identified different PTEN proteoforms, which control various aspects of cellular function and grouped them into three categories of intrinsic, function-induced, and inducible proteoforms. A special emphasis is given to the inducible PTEN proteoforms that are produced due to alternative translational initiation. The novel finding that PTEN forms dimers with biological implications supports the notion that PTEN proteoform-proteoform interactions may play hitherto unknown roles in cellular homeostasis and in pathogenic settings, including cancer. These PTEN proteoforms with unique properties and functionalities offer potential novel therapeutic opportunities in the treatment of various cancers and other diseases.

MicroRNA-21 regulates the ERK/NF-κB signaling pathway to affect the proliferation, migration, and apoptosis of human melanoma A375 cells by targeting SPRY1, PDCD4, and PTEN

This study aims to explore the effects of microRNA-21 (miR-21) and ERK/NF-κB signaling pathway on human melanoma A375 cells. The melanoma tissues and adjacent normal tissues were obtained from 45 melanoma patients. qRT-PCR was conducted to quantify the expression of miR-21 and the gene mRNA expressions. Human melanoma A375 cells were divided into the Mock, negative control (NC), miR-21 inhibitors, miR-21 inhibitors + siRNA-SPRY1, miR-21 inhibitors + siRNA-PDCD4, and miR-21 inhibitors + siRNA-PTEN groups. Western blotting was used to determine protein expressions. CCK8 assay and Transwell assay were performed to evaluate the proliferation, migration, and invasion of A375 cells. Annexin V/propidium iodide double staining was adopted to detect cell apoptosis. MiR-21 expression was higher in melanoma tissues than in adjacent tissues, while the mRNA and protein expressions of SPRY1, PDCD4, and PTEN were lower in melanoma tissues than in adjacent tissues. Compared with the Mock and NC groups, the miR-21 inhibitors group exhibited increased expressions of SPRY1, PDCD4, and PTEN and decreased expressions of ERK, p-ERK, NF-κB p65, and p-NF-κB p65. After transfection of miR-21 inhibitors, the proliferation, migration, and invasion of A375 cells were inhibited, while the apoptosis of A375 cells was promoted. However, the effects of miR-21 inhibitors on the growth, migration, invasion, and apoptosis of A375 cells were reversed after transfection of siRNA-SPRY1, siRNA-PDCD4, or siRNA-PTEN. MiR-21 can promote the proliferation, migration, and inhibit the apoptosis of human melanoma A375 cells by inhibiting SPRY1, PDCD4, and PTEN via ERK/NF-κB signaling pathway. © 2016 Wiley Periodicals, Inc.

Phosphorylation and inactivation of PTEN at residues Ser380/Thr382/383 induced by Helicobacter pylori promotes gastric epithelial cell survival through PI3K/Akt pathway

Phosphorylation of PTEN at residues Ser380/Thr382/383 leads to loss of phosphatase activity and tumor suppressor function. Here, we found that phosphorylation of PTEN at residues Ser380/Thr382/383 was increased with gastric carcinogenesis, and more importantly, Helicobacter pylori was a trigger of this modification in chronic non-atrophic gastritis. H. pylori could phosphorylate and inactivate PTEN in vivo and in vitro, resulting in survival of gastric epithelial cells. Furthermore, stable expression of dominant-negative mutant PTEN or inhibition of Akt prevented the enhanced survival induced by H. pylori. These results indicate that PTEN phosphorylation at residues Ser380/Thr382/383 is a novel mechanism of PTEN inactivation in gastric carcinogenesis, and H. pylori triggers this modification, resulting in activation of the PI3K/Akt pathway and promotion of cell survival.

Expression of PTEN and Its Correlation with Proliferation Marker Ki-67 in Head and Neck Cancer

Introduction

PTEN is part of large family of tyrosine phosphatases and has been found inactivated in a wide variety of human cancers.

Aims

In the present study we have tried to determine the association of the expression patterns of this gene with carcinogenesis.

Methods

First, a systematic review was carried out to ascertain the importance of the PTEN gene and its role in carcinogenesis. In the second phase, a case-control study was designed using different expression analysis techniques. Expression of PTEN mRNA was analyzed using reverse transcriptase polymerase chain reaction (RT-PCR).

Results

Significantly downregulated expression of PTEN was observed in patients with head and neck cancer (HNC) compared to adjacent normal-tissue controls. These results were confirmed with quantitative polymerase chain reaction (qPCR). Significant downregulation of the gene was observed in HNC patients compared to adjacent normal-tissue controls. PTEN expression was correlated with different histopathological parameters of the study cohort by Spearman's correlation coefficient and a significant negative correlation was observed with pT stage (r = −0.271*; p<0.02) and grade (r = −0.228*; p<0.02) of HNC tissues. Furthermore, the expression variations of PTEN were correlated with the expression pattern of the proliferation marker Ki-67. Significantly (p<0.008) upregulated expression of Ki-67 was observed in HNC patients compared with adjacent normal-tissue controls This upregulation of Ki-67 was confirmed at the protein level by immunohistochemistry in HNC patients. When Spearman's correlation was carried out a significant negative correlation was observed between PTEN and Ki-67 (r = −0.230*; p<0.03).

Conclusions

Our data suggest that downregulation of PTEN and overexpression of Ki-67 may contribute to the initiation and progression of HNC.

Potential effect of chronic Helicobacter pylori infection on glucose metabolism of Mongolian gerbils

AIM: To assess the effect of Helicobacter pylori (H. pylori) infection on metabolic parameters in Mongolian gerbils.

METHODS: A total of 40 male, 5- to 8-wk-old, specific-pathogen-free Mongolian gerbils (30-50 g) were randomly allocated into two groups: a control group (n = 20) and an H. pylori group (n = 20). After a two-week acclimation period, the control group was administered Brucella broth and the H. pylori group was challenged intra-gastrically five times every other day with approximately 10⁹/CFU H. pylori ATCC43504 (CagA+, VacA+). Each group was then divided into two subgroups, which were sacrificed at either 6 or 12 mo. The control and H. pylori subgroups each contained 10 Mongolian gerbils. Body weight, abdominal circumference, and body length were measured, and body mass index (BMI) and Lee’s index were calculated. Biochemical assays were used to detect serum indexes, including glucose, glycated hemoglobin (GHb), glycated hemoglobin A1c (HbA1c), triacylglycerol, and total cholesterol, using an automatic biochemistry analyzer. Inflammatory cytokines, including interleukin (IL)-1β, IL-2, IL-4, IL-10, IL-12, tumor necrosis factor-α (TNF-α) and interferon (IFN)-γ, were assayed using ELISA. The expression of insulin and insulin-like growth factor 1 (IGF-1) was detected by immunohistochemistry, and islet apoptosis was measured using the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay.

RESULTS: At each time point, body weight, abdominal circumference, BMI, and Lee’s index were increased after H. pylori infection. However, these differences were not significant. H. pylori infection significantly increased the GHb (5.45 ± 0.53 vs 4.98 ± 0.22, P < 0.05) and HbA1c (4.91 ± 0.61 vs 4.61 ± 0.15, P < 0.05) levels at 12 mo. We observed no significant differences in serum biochemical indexes, including fasting blood glucose, triacylglycerol and total cholesterol, at 6 or 12 mo after infection. H. pylori infection significantly increased the expression of IGF-1 (P < 0.05). Insulin levels from the pancreas and the apoptotic rate of islet β-cells remained unchanged. Also, we observed no significant differences among cytokines levels, including IL-1β, IL-2, IL-4, IL-10, IL-12, TNF-α and IFN-γ. IL-4 was the only exception, which increased at 6 (44.36 ± 25.17 vs 17.38 ± 3.47, P < 0.05) and 12 mo (33.41 ± 10.00 vs 18.91 ± 5.31, P < 0.05) after H. pylori infection.

CONCLUSION: Long-term H. pylori infection is significantly associated with high levels of HbA1c in Mongolian gerbils, indicating a potential role of H. pylori infection in glucose dysregulation.

Targeting the PI3K/Akt signaling pathway in gastric carcinoma: A reality for personalized medicine?

Frequent activation of phosphatidylinositol-3 kinases (PI3K)/Akt/mTOR signaling pathway in gastric cancer (GC) is gaining immense popularity with identification of mutations and/or amplifications of PIK3CA gene or loss of function of PTEN, a tumor suppressor protein, to name a few; both playing a crucial role in regulating this pathway. These aberrations result in dysregulation of this pathway eventually leading to gastric oncogenesis, hence, there is a need for targeted therapy for more effective anticancer treatment. Several inhibitors are currently in either preclinical or clinical stages for treatment of solid tumors like GC. With so many inhibitors under development, further studies on predictive biomarkers are needed to measure the specificity of any therapeutic intervention. Herein, we review the common dysregulation of PI3K/Akt/mTOR pathway in GC and the various types of single or dual pathway inhibitors under development that might have a superior role in GC treatment. We also summarize the recent developments in identification of predictive biomarkers and propose use of predictive biomarkers to facilitate more personalized cancer therapy with effective PI3K/Akt/mTOR pathway inhibition.

Deubiquitinases Modulate Platelet Proteome Ubiquitination, Aggregation, and Thrombosis

OBJECTIVE

Platelets express a functional ubiquitin-proteasome system. Mass spectrometry shows that platelets contain several deubiquitinases, but whether these are functional, modulate the proteome, or affect platelet reactivity are unknown.

APPROACH AND RESULTS

Platelet lysates contained ubiquitin-protein deubiquitinase activity hydrolyzing both Lys48 and Lys63 polyubiquitin conjugates that was suppressed by the chemically unrelated deubiquitinase inhibitors PYR41 and PR619. These inhibitors acutely and markedly increased monoubiquitination and polyubiquitination of the proteome of resting platelets. PYR41 (intravenous, 15 minutes) significantly impaired occlusive thrombosis in FeCl3-damaged carotid arteries, and deubiquitinase inhibition reduced platelet adhesion and retention during high shear flow of whole blood through microfluidic chambers coated with collagen. Total internal reflection microscopy showed that adhesion and spreading in the absence of flow were strongly curtailed by these inhibitors with failure of stable process extension and reduced the retraction of formed clots. Deubiquitinase inhibition also sharply reduced homotypic platelet aggregation in response to not only the incomplete agonists ADP and collagen acting through glycoprotein VI but also to the complete agonist thrombin. Suppressed aggregation was accompanied by curtailed procaspase activating compound-1 binding to activated IIb/IIIa and inhibition of P-selectin translocation to the platelet surface. Deubiquitinase inhibition abolished the agonist-induced spike in intracellular calcium, suppressed Akt phosphorylation, and reduced agonist-stimulated phosphatase and tensin homolog phosphatase phosphorylation. Platelets express the proteasome-associated deubiquitinases USP14 and UCHL5, and selective inhibition of these enzymes by b-AP15 reproduced the inhibitory effect of the general deubiquitinase inhibitors on ex vivo platelet function.

CONCLUSIONS

Remodeling of the ubiquitinated platelet proteome by deubiquitinases promotes agonist-stimulated intracellular signal transduction and platelet responsiveness.

Opisthorchis viverrini infection activates the PI3K/ AKT/PTEN and Wnt/β-catenin signaling pathways in a Cholangiocarcinogenesis model

Opisthorchis viverrini (Ov) infection is the major etiological factor for cholangiocarcinoma (CCA), especially in northeast Thailand. We have previously reported significant involvement of PI3K/AKT/PTEN and Wnt/β- catenin in human CCA tissues. The present study, therefore, examined the expression and activation of PI3K/ AKT/PTEN and Wnt/β-catenin signaling components during Ov-induced cholangiocarcinogenesis in a hamster animal model. Hamsters were divided into two groups; non-treated and Ov plus NDMA treated. The results of immunohistochemical staining showed an upregulation of PI3K/AKT signaling as determined by elevated expression of the p85α-regulatory and p110α-catalytic subunits of PI3K as well as increased expression and activation of AKT during cholangiocarcinogenesis. Interestingly, the staining intensity of activated AKT (p-AKT) increased in the apical regions of the bile ducts and strong staining was detected where the liver fluke resides. Moreover, PTEN, a negative regulator of PI3K/AKT, was suppressed by decreased expression and increased phosphorylation during cholangiocarcinogenesis. We also detected upregulation of Wnt/β-catenin signaling as determined by increased positive staining of Wnt3, Wnt3a, Wnt5a, Wnt7b and β-catenin, corresponded with the period of cholangiocarcinogenesis. Furthermore, nuclear staining of β-catenin was observed in CCA tissues. Our results suggest the liver fluke infection causes chronic inflammatory conditions which lead to upregulation of the PI3K/AKT and Wnt/β-catenin signaling pathways which may drive CCA carcinogenesis. These results provide useful information for drug development, prevention and treatment of CCA.

Focus on PTEN Regulation

The role of phosphatase and tensin homolog on chromosome 10 (PTEN) as a tumor suppressor has been for a long time attributed to its lipid phosphatase activity against PI(3,4,5)P₃, the phospholipid product of the class I PI3Ks. Besides its traditional role as a lipid phosphatase at the plasma membrane, a wealth of data has shown that PTEN can function independently of its phosphatase activity and that PTEN also exists and plays a role in the nucleus, in cytoplasmic organelles, and extracellularly. Accumulating evidence has shed light on diverse physiological functions of PTEN, which are accompanied by a complex regulation of its expression and activity. PTEN levels and function are regulated transcriptionally, post-transcriptionally, and post-translationally. PTEN is also sensitive to regulation by its interacting proteins and its localization. Herein, we summarize the current knowledge on mechanisms that regulate the expression and enzymatic activity of PTEN and its role in human diseases.

GD2 ganglioside specific antibody treatment downregulates PI3K/Akt/mTOR signaling network in human neuroblastoma cell lines

Mechanisms leading to inhibitory effects of an anti-GD2 ganglioside (GD2) 14G2a mouse monoclonal antibody (mAb) and PI3K/Akt/mTOR pathway inhibitors on human neuroblastoma cell survival were studied in vitro. We have recently shown on IMR-32, CHP‑134, and LA-N-1 neuroblastoma cells that targeting GD2 with the mAb decreases cell viability of the cell lines. In this study we used cytotoxicity assays, proteomic arrays and immunoblotting to evaluate the response of the three cell lines to the anti‑GD2 14G2a mAb and specific PI3K/Akt/mTOR pathway inhibitors. We show here that the mAb modulates intracellular signal transduction through changes in several kinases and their substrates phosphorylation. More detailed analysis of the PI3K/Akt/mTOR pathway showed significant decrease in activity of Akt, mTOR, p70 S6 and 4E-BP1 proteins and transient increase in PTEN (a suppressor of the pathway), leading to inhibition of the signaling network responsible for stimulation of translation and proliferation. Additionally, combining the GD2-specific 14G2a mAb with an Akt inhibitor (perifosine), dual mTOR/PI3K inhibitors (BEZ-235 and SAR245409), and a pan-PI3K inhibitor (LY294002) was shown to enhance cytotoxic effects against IMR-32, CHP‑134 and LA-N-1 cells. Our study extends knowledge on mechanisms of action of the 14G2a mAb on the neuroblastoma cells. Also, it stresses the need for further delineation of molecular signal orchestration aimed at more reasonable selection of drugs to target key cellular pathways in quest for better cure for neuroblastoma patients.

PTEN loss is associated with follicular variant of Middle Eastern papillary thyroid carcinoma

Background:

PTEN gene at chromosomes 10q23.3 is a tumour suppressor gene that is inactivated in many types of human cancers. The known mechanisms of PTEN inactivation are rendered to mutation, epigenetic silencing by aberrant methylation or gene deletion. Although PTEN role has been documented in many cancers, PTEN alteration in papillary thyroid carcinoma (PTC) has not been fully elucidated. The aim of this study is to comprehensively investigate PTEN alterations in a large cohort of Middle Eastern papillary thyroid cancer by immunohistochemistry and fluorescent in situ hybridisation (FISH).

Methods:

PTEN protein expression was analysed by immunohistochemistry in a tissue microarray (TMA) format in a large cohort of more than 1000 patients with papillary thyroid cancer. Copy number changes in PTEN were analysed by FISH and data were correlated with clinicopathological parameters along with survival analysis.

Results:

PTEN inactivation reflected by complete absence of staining was seen in 24.5% of PTC samples, whereas PTEN deletion was seen only in 4.8% of the tested samples by FISH. No association was seen between PTEN loss of protein expression and PTEN gene deletion. However, interestingly, PTEN loss of expression was significantly associated with the follicular variant subset of papillary thyroid cancer.

Conclusion:

Our study confirmed that PTEN might have a role in pathogenesis in a subset of PTC. PTEN loss of protein expression is a more common event in follicular variant of papillary thyroid cancer. Lack of association between PTEN loss of protein expression and PTEN gene deletion might indicate that gene deletion may not be the sole cause for PTEN loss of expression and these results might raise the possibility of other mechanism such as promoter methylation-mediated gene silencing to be responsible for PTEN inactivation.

AKT and MET signalling mediates antiapoptotic radioresistance in head neck cancer cell lines

OBJECTIVES

Induction of apoptosis is a major mechanism of radiosensitivity in different types of cancer. In contrast, EGFR/PI3K/AKT signalling and recently the presence of so-called cancer stem cells are discussed as reasons for radioresistance.

MATERIALS AND METHODS

The study investigates mechanisms of apoptosis, key oncogenes of the PI3K/AKT pathway and the presence of cancer cells with stem cell properties during irradiation in two cell lines (PCI-9A, and PCI-15) of head and neck squamous cell carcinoma. WST-1-tests, qRT-PCR, western blots and FACS analysis were performed for analysis.

RESULTS

The two cell lines presented different degrees of cell death upon irradiation. The radiosensitive cell line PCI-9A showed increased apoptosis after irradiation measured by expressed cleaved caspases 3 and 7 while the radioresistant cell line PCI-15 upregulated antiapoptotic Survivin and BCL2A1 mRNA. Besides, increased PI3K/AKT- and ERK1/2-signalling was associated with radioresistance accompanied by loss of PTEN function through phosphorylation on S380. Blockade of pAKT increased radiation-induced cell death, and moreover, led to an upregulation of pMET in the radioresistant cell line. The percentage of ALDH-positive tumour cells was markedly decreased after irradiation in the radiosensitive cell line.

CONCLUSIONS

Functional apoptosis is mandatory for sensitivity to irradiation in head neck cancer cells. Upregulation of the AKT-pathway seems to be one reason for poor radioresponse. Activated MET may also predict radioresistance, possibly through ERK1/2 signalling. Moreover MET may indicate the presence of cancer stem cells facilitating radioresistance as shown by increased ALDH expression.

Roles of PTEN (Phosphatase and Tensin Homolog) in gastric cancer development and progression

Gastric cancer is highly invasive, aggressively malignant, and amongst the most prevalent of all forms of cancer. Despite improved management strategies, early stage diagnosis of gastric cancer and accurate prognostic assessment is still lacking. Several recent reports have indicated that the pathogenesis of gastric cancer involves complex molecular mechanisms and multiple genetic and epigenetic alterations in oncogenes and tumor suppressor genes. Functional inactivation of the tumor suppressor protein PTEN (Phosphatase and Tensin Homolog) has been detected in multiple cases of gastric cancer, and already shown to be closely linked to the development, progression and prognosis of the disease. Inactivation of PTEN can be attributed to gene mutation, loss of heterozygosity, promoter hypermethylation, microRNA- mediated regulation of gene expression, and post-translational phosphorylation. PTEN is also involved in mechanisms regulating tumor resistance to chemotherapy. This review provides a comprehensive analysis of PTEN and its roles in gastric cancer, and emphasizes its potential benefits in early diagnosis and gene therapy-based treatment strategies.

Posttranslational regulation of phosphatase and tensin homolog (PTEN) and its functional impact on cancer behaviors

The incidence of cancer is increasing worldwide, but the biochemical mechanisms for the occurrence of cancer is not fully understood, and there is no cure for advanced tumors. Defects of posttranslational modifications of proteins are linked to a number of important diseases, such as cancer. This review will update our knowledge on the critical role of posttranscriptional regulation of phosphatase and tensin homolog (PTEN) and its activities and the functional impact on cancer behaviors. PTEN is a tumor suppressor gene that occupies a key position in regulating cell growth, proliferation, apoptosis, mobility, signal transduction, and other crucial cellular processes. The activity and function of PTEN are regulated by coordinated epigenetic, transcriptional, posttranscriptional, and posttranslational modifications. In particular, PTEN is subject to phosphorylation, ubiquitylation, somoylation, acetylation, and active site oxidation. Posttranslational modifications of PTEN can dynamically change its activity and function. Deficiency in the posttranslational regulation of PTEN leads to abnormal cell proliferation, apoptosis, migration, and adhesion, which are associated with cancer initiation, progression, and metastasis. With increasing information on how PTEN is regulated by multiple mechanisms and networked proteins, its exact role in cancer initiation, growth, and metastasis will be revealed. PTEN and its functionally related proteins may represent useful targets for the discovery of new anticancer drugs, and gene therapy and the therapeutic potentials should be fully explored.

PTEN function: the long and the short of it

Phosphatase and tensin homolog deleted on chromosome ten (PTEN) is a phosphatase that is frequently altered in cancer. PTEN has phosphatase-dependent and -independent roles, and genetic alterations in PTEN lead to deregulation of protein synthesis, the cell cycle, migration, growth, DNA repair, and survival signaling. PTEN localization, stability, conformation, and phosphatase activity are controlled by an array of protein-protein interactions and post-translational modifications. Thus, PTEN-interacting and -modifying proteins have profound effects on the tumor suppressive functions of PTEN. Moreover, recent studies identified mechanisms by which PTEN can exit cells, via either exosomal export or secretion, and act on neighboring cells. This review focuses on modes of PTEN protein regulation and ways in which perturbations in this regulation may lead to disease.

Loss of NDRG2 expression activates PI3K-AKT signalling via PTEN phosphorylation in ATLL and other cancers

Constitutive phosphatidylinositol 3-kinase (PI3K)-AKT activation has a causal role in adult T-cell leukaemia-lymphoma (ATLL) and other cancers. ATLL cells do not harbour genetic alterations in PTEN and PI3KCA but express high levels of PTEN that is highly phosphorylated at its C-terminal tail. Here we report a mechanism for the N-myc downstream-regulated gene 2 (NDRG2)-dependent regulation of PTEN phosphatase activity via the dephosphorylation of PTEN at the Ser380, Thr382 and Thr383 cluster within the C-terminal tail. We show that NDRG2 is a PTEN-binding protein that recruits protein phosphatase 2A (PP2A) to PTEN. The expression of NDRG2 is frequently downregulated in ATLL, resulting in enhanced phosphorylation of PTEN at the Ser380/Thr382/Thr383 cluster and enhanced activation of the PI3K-AKT pathway. Given the high incidence of T-cell lymphoma and other cancers in NDRG2-deficient mice, PI3K-AKT activation via enhanced PTEN phosphorylation may be critical for the development of cancer.

The combination of RAD001 and MK-2206 exerts synergistic cytotoxic effects against PTEN mutant gastric cancer cells: involvement of MAPK-dependent autophagic, but not apoptotic cell death pathway

In the current study, we showed that the combination of mammalian target of rapamycin (mTOR) inhibitor RAD001 (everolimus) and Akt inhibitor MK-2206 exerted synergistic cytotoxic effects against low-phosphatase and tensin homolog (PTEN) gastric cancer cells (HGC-27 and SNU-601 lines). In HGC-27 cells, RAD001 and MK-2206 synergistically induced G1/S cell cycle arrest, growth inhibition, cell death but not apoptosis. RAD001 and MK-2206 synergistically induced light chain 3B (LC3B) and beclin-1 expression, two important autophagy indicators. Meanwhile, the autophagy inhibitor 3-methyladenine (3-MA) and chloroquine inhibited the cytotoxic effects by RAD001 and MK-2206, suggesting that autophagic, but not apoptotic cell death was important for the cytotoxic effects by the co-administration. We observed that the combination of RAD001 and MK-2206 exerted enhanced effects on Akt/mTOR inhibition, cyclin D1 down-regulation and ERK/MAPK(extracellular signal-regulated kinase/mitogen-activated protein kinases) activation. Intriguingly, MEK/ERK inhibitors PD98059 and U0126 suppressed RAD001 plus MK-2206-induced beclin-1 expression, autophagy induction and cytotoxicity in HGC-27 cells. In conclusion, these results suggested that the synergistic anti-gastric cancer cells ability by RAD001 and MK-2206 involves ERK-dependent autophagic cell death pathway.

Expression of γH2AX in various gastric pathologies and its association with Helicobacter pylori infection

Phosphorylation of H2AX at Ser 139 (γH2AX) is a biomarker of DNA double-strand breaks (DSBs). The present study aimed to explore the association between γH2AX levels and gastric pathology and Helicobacter pylori (H. pylori) infection. Gastric biopsies were obtained from 302 H. pylori-negative and -positive patients, including those with chronic gastritis (CG), intestinal metaplasia (IM), dysplasia (Dys) and gastric cancer (GC). Proteins were extracted from five gastric epithelial cell lines and from 10 specimens of matched GC and adjacent normal tissues. The expression of γH2AX, a biomarker for the detection of DNA DSBs, in gastric tissues was detected by immunohistochemistry and western blotting. The expression of γH2AX progressively increased in tissues according to pathological stage from CG to Dys, but was slightly decreased in GC. H. pylori infection was associated with increased γH2AX expression, IM and Dys. Overexpression of γH2AX in GC was found to correlate with tumor location, gross appearance, differentiation, depth of invasion, TNM stage and lymph node metastasis. The results indicated that DSBs appear to be an early molecular event in gastric carcinogenesis, which may be associated with H. pylori infection. Moreover, immunohistochemical staining of γH2AX was found to correlate with a number of clinicopathological characteristics. The expression of γH2AX may serve as a valuable biomarker for the diagnosis and progression of GC.

Phosphorylated SATB1 is associated with the progression and prognosis of glioma

Special AT-rich sequence-binding protein 1 (SATB1) is a global chromatin organizer and gene regulator, and high expression of SATB1 is associated with progression and poor prognosis in several malignancies. Here, we examine the expression pattern of SATB1 in glioma. Microarray analysis of 127 clinical samples showed that SATB1 mRNA was expressed at lower levels in highly malignant glioblastoma multiforme (GBM) than in low-grade glioma and normal brain tissue. This result was further confirmed by real-time RT-PCR in the clinical samples, three GBM cell lines, primary SU3 glioma cells and tumor cells harvested by laser-capture microdissection. Consistent with the mRNA levels, SATB1 protein expression was downregulated in high-grade glioma, as shown by western blotting. However, phospho-SATB1 levels showed an opposite pattern, with a significant increase in these tumors. Immunohistochemical analysis of phospho-SATB1 expression in tissue microarrays with tumors from 122 glioma cases showed that phospho-SATB1 expression was significantly associated with high histological grade and poor survival by Kaplan–Meier analysis. In vitro transfection analysis showed that phospho-SATB1 DNA binding has a key role in regulating the proliferation and invasion of glioma cells. The effect of SATB1 in glioma cell is mainly histone deacetylase (HDAC1)-dependent. We conclude that phospho-SATB1, but not SATB1 mRNA expression, is associated with the progression and prognosis of glioma. By interaction with HDAC1, phospho-SATB1 contributes to the invasive and proliferative phenotype of GBM cells.

BCCIP suppresses tumor initiation but is required for tumor progression

Dysfunctions of genome caretaker genes contribute to genomic instability and tumor initiation. Because many of the caretaker genes are also essential for cell viability, permanent loss of function of these genes would prohibit further tumor progression. How essential caretaker genes contribute to tumorigenesis is not fully understood. Here, we report a "hit-and-run" mode of action for an essential caretaker gene in tumorigenesis. Using a BRCA2-interacting protein BCCIP as the platform, we found that a conditional BCCIP knockdown and concomitant p53 deletion caused rapid development of medulloblastomas, which bear a wide spectrum of alterations involving the Sonic Hedgehog (Shh) pathway, consistent with a caretaker responsibility of BCCIP on genomic integrity. Surprisingly, the progressed tumors have spontaneously lost the transgenic BCCIP knockdown cassette and restored BCCIP expression. Thus, a transient downregulation of BCCIP, but not necessarily a permanent mutation, is sufficient to initiate tumorigenesis. After the malignant transformation has been accomplished and autonomous cancer growth has been established, BCCIP reverses its role from a tumor-initiation suppressor to become a requisite for progression. This exemplifies a new type of tumor suppressor, which is distinct from the classical tumor suppressors that are often permanently abrogated during tumorigenesis. It has major implications on how a nonmutagenic or transient regulation of essential caretaker gene contributes to tumorigenesis. We further suggest that BCCIP represents a paradoxical class of modulators for tumorigenesis as a suppressor for initiation but a requisite for progression (SIRP).