Overexpression of protein phosphatase non-receptor type 11 (PTPN11) in gastric carcinomas

Computational Elucidation of a Monobody Targeting the Phosphatase Domain of SHP2

Src homology 2 (SH2) domain-containing phosphatase 2 (SHP2) is a key regulator in cellular signaling pathways because its dysregulation has been implicated in various pathological conditions, including cancers and developmental disorders. Despite its importance, the molecular basis of SHP2's regulatory mechanism remains poorly understood, hindering the development of effective targeted therapies. In this study, we utilized the high-specificity monobody Mb11 to investigate its interaction with the SHP2 phosphatase domain (PTP) using multiple replica molecular dynamics simulations. Our analyses elucidate the precise mechanisms through which Mb11 achieves selective recognition and stabilization of the SHP2-PTP domain, identifying key residues and interaction networks essential for its high binding specificity and regulatory dynamics. Furthermore, the study highlights the pivotal role of residue C459 in preserving the structural integrity and functional coherence of the complex, acting as a central node within the interaction network and underpinning its stability and efficiency. These findings have significantly advanced the understanding of the mechanisms underlying SHP2's involvement in disease-related signaling and pathology while simultaneously paving the way for the rational design of targeted inhibitors, offering significant implications for therapeutic strategies in SHP2-associated diseases and contributing to the broader scope of precision medicine.

Dihydrotanshinone I induces necroptosis and cell cycle arrest in gastric cancer through the PTPN11/p38 pathway

In this study, MTT assays, apoptosis detection, immunofluorescence, and functional studies were used to elucidate the mechanisms underlying the effects of dihydrotanshinone I (DHT) on gastric cancer cells. Drug target prediction and analysis were conducted to identify potential targets of DHT. MTT assay revealed significant inhibition of AGS and HGC27 cells by DHT. Morphological changes, including nuclear shrinkage and the induction of necrotic cell death, were observed in DHT-treated gastric cancer cells, along with cell cycle arrest at the G2/M phase. Further analysis revealed potential targets of DHT, including PTPN11, which is highly expressed in gastric cancer cells. DHT treatment increased necrosis-related proteins (RIPK1/RIPK3/MLKL) and downregulated cell cycle-related proteins (CDC25C and CDK1) levels in gastric cancer cells. After DHT treatment, PTPN11 protein expression decreased. Furthermore, DHT significantly increased the phosphorylated p38/JNK protein level, with the phosphorylated p38 protein notably enriched in the nucleus. These functional studies indicate that PTPN11 plays a key role in mediating the effects of DHT, including cell cycle regulation and necrosis induction. In conclusion, PTPN11 is a central target through which DHT affects gastric cancer cells, regulating downstream pathways involved in necroptosis (p38/RIPK1/RIPK3/MLKL/JNK) and cell cycle arrest (p38/CDC25C/CDK1).

SHP2 is involved in the occurrence, development and prognosis of cancer

Src homology-2 domain-containing protein tyrosine phosphatase (SHP2), encoded by protein tyrosine phosphatase non-receptor type 11 (PTPN11), is widely expressed in several human tissue types, and plays an important role in a variety of diseases. The present study assessed the impact of SHP2 on the occurrence, development and prognosis of solid tumors. The transcriptome sequencing data of 33 cancer types were downloaded from The Cancer Genome Atlas database. Clinical information of the corresponding patients, tumor mutational burden and information pertinent to microsatellite instability were also downloaded. The log-rank test and univariate Cox's regression test were used to evaluate patient survival. The 'ESTIMATE' method was used to assess the tumor microenvironment, and the 'CIBERSORT' algorithm was used to evaluate tumor immune cell infiltration. Spearman's correlation analysis was used to evaluate the correlation between SHP2 expression and the targets identified. ELISA was used to assess the SHP2 expression levels in peripheral blood samples of patients with breast, ovarian, endometrial and cervical cancer. The data indicated that the expression levels of SHP2 were increased in a variety of tumor tissues, and were associated with tumor progression and prognosis. In peripheral blood, the positive rates of SHP2 expression in breast cancer (71.43%) and ovarian cancer (58.82%) were significantly higher than those in the corresponding control groups. However, the positive rates of SHP2 expression in patients with endometrial cancer (31.03%) and cervical cancer (41.30%) were significantly lower than those in the corresponding control groups. Increased SHP2 expression improved overall survival (OS) and disease free survival (DFS) time in patients with kidney renal clear cell carcinoma. However, increased SHP2 expression reduced OS and DFS in patients with urothelial carcinoma, and cervical and endocervical cancer types. Moreover, the elevated expression of SHP2 could also reduce the OS of patients with breast invasive carcinoma, mesothelioma and liver hepatocellular carcinoma. PTPN11 expression was associated with the tumor microenvironment of various tumor types. The tumor mutational burden of various tumor types was associated with microsatellite instability. PTPN11 inhibited T-cell activation and promoted M2 macrophage activation in several tumors. Therefore, SHP2 may be used in the evaluation of tumor progression and prognosis, and it may be an optimal potential biological target for cancer therapy.

Setting sail: Maneuvering SHP2 activity and its effects in cancer

Since the discovery of tyrosine phosphorylation being a critical modulator of cancer signaling, proteins regulating phosphotyrosine levels in cells have fast become targets of therapeutic intervention. The nonreceptor protein tyrosine phosphatase (PTP) coded by the PTPN11 gene "SHP2" integrates phosphotyrosine signaling from growth factor receptors into the RAS/RAF/ERK pathway and is centrally positioned in processes regulating cell development and oncogenic transformation. Dysregulation of SHP2 expression or activity is linked to tumorigenesis and developmental defects. Even as a compelling anti-cancer target, SHP2 was considered "undruggable" for a long time owing to its conserved catalytic PTP domain that evaded drug development. Recently, SHP2 has risen from the "undruggable curse" with the discovery of small molecules that manipulate its intrinsic allostery for effective inhibition. SHP2's unique domain arrangement and conformation(s) allow for a truly novel paradigm of inhibitor development relying on skillful targeting of noncatalytic sites on proteins. In this review we summarize the biological functions, signaling properties, structural attributes, allostery and inhibitors of SHP2.

Effects of copper exposure on lipid metabolism and SREBP pathway in the Chinese mitten crab Eriocheir sinensis

Copper (Cu) is not only a common metal pollutant in the aquatic environment but also an essential trace element for aquatic organisms such as the Chinese mitten crab (Eriocheir sinensis). Cu is known to regulate lipid metabolism yet exert toxic effects if ingested in excess. However, the molecular regulatory roles of Cu in the lipid metabolism of crabs remains unclear. Thus, this study investigated the potential regulatory mechanism of Cu onto lipid metabolism of E. sinensis following acute Cu exposure. Crabs were exposed to environmental concentration of Cu (50 μg/L) for 96 h, and the expression of sterol regulatory element binding protein (SREBP) was knocked down by RNA interference (RNAi) to test its effect on Cu exposure. The results showed that RNAi significantly attenuated the Cu exposure-induced increase in lipid synthesis and triglycerides (TG) hydrolysis, while significantly inhibited the Cu exposure-induced decrease in fatty acid β-oxidation, suggesting that SREBP is involved in Cu-induced lipid metabolism. Subsequent analyses of the transcriptome results further revealed potential responsive genes of SREBP that were linked to lipid metabolism and immune regulation. Moreover, Cu may affect lipid metabolism through the TOR-SREBP pathway in E. sinensis. This work provides a reference for exploring the effects of Cu on lipid metabolism disorders in crustaceans.

A comprehensive review of SHP2 and its role in cancer

Src homology 2-containing protein tyrosine phosphatase 2 (SHP2) is a non-receptor protein tyrosine phosphatase ubiquitously expressed mainly in the cytoplasm of several tissues. SHP2 modulates diverse cell signaling events that control metabolism, cell growth, differentiation, cell migration, transcription and oncogenic transformation. It interacts with diverse molecules in the cell, and regulates key signaling events including RAS/ERK, PI3K/AKT, JAK/STAT and PD-1 pathways downstream of several receptor tyrosine kinases (RTKs) upon stimulation by growth factors and cytokines. SHP2 acts as both a phosphatase and a scaffold, and plays prominently oncogenic functions but can be tumor suppressor in a context-dependent manner. It typically acts as a positive regulator of RTKs signaling with some inhibitory functions reported as well. SHP2 expression and activity is regulated by such factors as allosteric autoinhibition, microRNAs, ubiquitination and SUMOylation. Dysregulation of SHP2 expression or activity causes many developmental diseases, and hematological and solid tumors. Moreover, upregulated SHP2 expression or activity also decreases sensitivity of cancer cells to anticancer drugs. SHP2 is now considered as a compelling anticancer drug target and several classes of SHP2 inhibitors with different mode of action are developed with some already in clinical trial phases. Moreover, novel SHP2 substrates and functions are rapidly growing both in cell and cancer. In view of this, we comprehensively and thoroughly reviewed literatures about SHP2 regulatory mechanisms, substrates and binding partners, biological functions, roles in human cancers, and different classes of small molecule inhibitors target this oncoprotein in cancer.

Prognostic significance of SHP2 (PTPN11) expression in solid tumors: A meta-analysis

Background

SHP2 is a latent biomarker for predicting the survivals of solid tumors. However, the current researches were controversial. Therefore, a meta-analysis is necessary to assess the prognosis of SHP2 on tumor patients.

Materials and methods

Searched in PubMed, EMBASE and web of science databases for published studies until Jun 20, 2021. A meta-analysis was performed to evaluate the affect of SHP2 in clinical stages, disease-free survival (DFS) and overall survival (OS) in tumor patients.

Results

This study showed that the expression of SHP2 had no significant correlation with clinical stages (OR: 0.91; 95% CI, 0.60–1.38; P = 0.65), DFS (HR = 0.88; 95%CI: 0.58–1.34; P = 0.56) and OS (HR = 1.07, 95%CI: 0.79–1.45, P = 0.67), but the prognostic effect varied greatly with tumor sites. High SHP2 expression was positively related to early clinical stage in hepatocellular carcinoma, not associated with clinical stage in the most of solid tumors, containing laryngeal carcinoma, pancreatic carcinoma and gastric carcinoma, etc. Higher expression of SHP2 could predict longer DFS in colorectal carcinoma, while predict shorter DFS in hepatocellular carcinoma. No significant difference was observed in DFS for non-small cell lung carcinoma and thyroid carcinoma. Higher SHP2 expression was distinctly related to shorter OS in pancreatic carcinoma and laryngeal carcinoma. The OS of the other solid tumors was not significantly different.

Conclusions

The prognostic value of SHP2 might not equivalent in different tumors. The prognostic effect of SHP2 is highly influenced by tumor sites.

Protein Tyrosine Phosphatases: Mechanisms in Cancer

Protein tyrosine kinases, especially receptor tyrosine kinases, have dominated the cancer therapeutics sphere as proteins that can be inhibited to selectively target cancer. However, protein tyrosine phosphatases (PTPs) are also an emerging target. Though historically known as negative regulators of the oncogenic tyrosine kinases, PTPs are now known to be both tumor-suppressive and oncogenic. This review will highlight key protein tyrosine phosphatases that have been thoroughly investigated in various cancers. Furthermore, the different mechanisms underlying pro-cancerous and anti-cancerous PTPs will also be explored.

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.

PTPN11 hypomethylation is associated with gastric cancer progression

Protein tyrosine phosphatase non-receptor type 11 (PTPN11) encodes the tyrosine phosphatase SHP-2 that is overexpressed in gastric cancer (GC). In the present study, the association of PTPN11 methylation levels with the incidence of GC and its correlation with SHP-2 overexpression were investigated. The methylation levels of PTPN11 in tumor and adjacent normal tissues of 112 GC patients were assessed by quantitative methylation specific PCR (qMSP). The Cancer Genome Atlas (TCGA) public database was used to analyze the association between PTPN11 methylation and PTPN11 expression. Survival analyses were conducted in order to evaluate the prognostic value of PTPN11 methylation for GC. The results of the qMSP analysis indicated that the methylation levels of PTPN11 in GC tumor tissues were significantly decreased compared with those noted in the normal adjacent tissues (mean with standard deviation: 40.91±26.33 vs. 51.99±37.37, P=0.007). An inverse correlation between PTPN11 methylation levels and PTPN11 mRNA expression levels (P=4×10^-6, r=-0.237) was noted. Subgroup analyses indicated that the association of PTPN11 hypomethylation with the incidence of GC was specific to male subjects (P=0.015), heavy drinking patients (P=0.019), patients with poor tumor differentiation (P=0.010) and patients with tumor node and metastasis (TNM) stage III+IV (P=0.008). Kaplan-Meier analyses and log-rank test suggested that PTPN11 hypomethylation was not associated with GC patient overall survival (P=0.605) and recurrence (P=0.485), although it could predict the recurrence of GC patients up to and including 60 years (≤60, P=0.049). The results indicated that PTPN11 levels were hypomethylated in GC patients. TCGA data analysis suggested that PTPN11 hypomethylation could cause an upregulation in the transcription levels of PTPN11. Although, this may explain the pattern of SHP-2 overexpression in GC, additional studies are required to verify this hypothesis. The association of PTPN11 hypomethylation with GC incidence may be specific to male patients, heavy drinking patients, patients with poor tumor differentiation and patients with TNM stage of III+IV. PTPN11 hypomethylation can be considered a biomarker for the recurrence of GC patients with an age of 60 years or lower.

Therapeutic potential of targeting SHP2 in human developmental disorders and cancers

Src homology 2 (SH2)-containing protein tyrosine phosphatase 2 (SHP2), encoded by PTPN11, regulates cell proliferation, differentiation, apoptosis and survival via releasing intramolecular autoinhibition and modulating various signaling pathways, such as mitogen-activated protein kinase (MAPK) pathway. Mutations and aberrant expression of SHP2 are implicated in human developmental disorders, leukemias and several solid tumors. As an oncoprotein in some cancers, SHP2 represents a rational target for inhibitors to interfere. Nevertheless, its tumor suppressive effect has also been uncovered, indicating the context-specificity. Even so, two types of SHP2 inhibitors including targeting catalytic pocket and allosteric sites have been developed associated with resolved cocrystal complexes. Herein, we describe its structure, biological function, deregulation in human diseases and summarize recent advance in development of SHP2 inhibitors, trying to give an insight into the therapeutic potential in future.

Tumorigenic role of YAP in hepatocellular carcinogenesis is involved in SHP2 whose function is different in vitro and in vivo

Yes-associated protein (YAP) is a nuclear effector of the cell-density sensing Hippo pathway and interacts with Src homology phosphotyrosine phosphatase 2 (SHP2), which controls cell proliferation and survival. The tumor promoting/suppressing activities of YAP and SHP2 during liver tumorigenesis remain controversial. This study aimed to investigate the tumorigenic roles of YAP and SHP2 in hepatocellular carcinogenesis. Cell density associated subcellular distributions of YAP and SHP2 in normal human hepatocytes (THLE-2) and hepatocellular carcinoma (HCC) cells (SK-Hep1, SNU-182) were investigated by Western blotting and cell block immunohistochemistry. The effects of YAP knockdown on proliferation, migration and invasion were studied using YAP-specific siRNAs. The prognostic significance of YAP and SHP2 expressions was investigated immunohistochemically using a tissue microarray (TMA) from 50 HCC cases. High-cell density decreased the nuclear expression of YAP and SHP2 in normal hepatocytes as compared with low-cell density. However, in HCC cells, nuclear YAP and SHP2 were observed regardless of cell density. Nuclear YAP influenced SHP2 expression and cell proliferation. In particular, YAP knockdown impacted nuclear levels of SHP2 protein in SK-Hep1 cells. In HCC tissues, nuclear YAP expression was elevated and cytoplasmic SHP2 expression was diminished as compared with adjacent non-tumor tissues. Notably, these expressions were found to be significantly associated with poor recurrence-free and overall survival rate in patients with HCC. Consequently, the tumor promoting role of YAP is involved in SHP2 which functions as a tumor promoter in vitro but as a tumor suppressor in vivo. YAP and SHP2 can be unfavorable prognostic markers in HCC.

The Roles of Protein Tyrosine Phosphatases in Hepatocellular Carcinoma

The protein tyrosine phosphatase (PTP) family is involved in multiple cellular functions and plays an important role in various pathological and physiological processes. In many chronic diseases, for example cancer, PTP is a potential therapeutic target for cancer treatment. In the last two decades, dozens of PTP inhibitors which specifically target individual PTP molecules were developed as therapeutic agents. Hepatocellular carcinoma (HCC) is one of the most common malignant tumors and is the second most lethal cancer worldwide due to a lack of effective therapies. Recent studies have unveiled both oncogenic and tumor suppressive functions of PTP in HCC. Here, we review the current knowledge on the involvement of PTP in HCC and further discuss the possibility of targeting PTP in HCC.

Identification of genomic aberrations in hemangioblastoma by droplet digital PCR and SNP microarray highlights novel candidate genes and pathways for pathogenesis

Background

The genetic mechanisms underlying hemangioblastoma development are still largely unknown. We used high-resolution single nucleotide polymorphism microarrays and droplet digital PCR analysis to detect copy number variations (CNVs) in total of 45 hemangioblastoma tumors.

Results

We identified 94 CNVs with a median of 18 CNVs per sample. The most frequently gained regions were on chromosomes 1 (p36.32) and 7 (p11.2). These regions contain the EGFR and PRDM16 genes. Recurrent losses were located at chromosome 12 (q24.13), which includes the gene PTPN11.

Conclusions

Our findings provide the first high-resolution genome-wide view of chromosomal changes in hemangioblastoma and identify 23 candidate genes: EGFR, PRDM16, PTPN11, HOXD11, HOXD13, FLT3, PTCH, FGFR1, FOXP1, GPC3, HOXC13, HOXC11, MKL1, CHEK2, IRF4, GPHN, IKZF1, RB1, HOXA9, and micro RNA, such as hsa-mir-196a-2 for hemangioblastoma pathogenesis. Furthermore, our data implicate that cell proliferation and angiogenesis promoting pathways may be involved in the molecular pathogenesis of hemangioblastoma.

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

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

Novel effects of Helicobacter pylori CagA on key genes of gastric cancer signal transduction: a comparative transfection study

Helicobacter pylori (H. pylori) infection is now recognized as a worldwide problem. Helicobacter pylori CagA is the first bacterial oncoprotein to be identified in relation to human cancer. Helicobacter pylori CagA is noted for structural diversity in its C-terminal region (contains EPIYA motifs), with which CagA interacts with numerous host cell proteins. Deregulation of host signaling by translocated bacterial proteins provides a new aspect of microbial-host cell interaction. The aim of this study is to compare the cellular effects of two different CagA EPIYA motifs on identified signaling pathways involve in gastric carcinogenesis. To investigate the effects of CagA protein carboxyl region variations on the transcription of genes involved in gastric epithelial carcinogenesis pathways, the eukaryotic vector carrying the cagA gene (ABC and ABCCC types) was transfected into gastric cancer cell line. The 42 identified key genes of signal transduction involved in gastric cancer were analyzed at the transcription level by real-time PCR. The results of real-time PCR provide us important clue that the ABCCC oncoprotein variant can change the fate of the cell completely different from ABC type. In fact, these result proposed that the ABCCC type can induce the intestinal metaplasia, IL-8, perturbation of Crk adaptor proteins, anti-apoptotic effect and carcinogenic effect more significantly than ABC type. These data support our hypothesis of a complex interaction of host cell and these two different H. pylori effector variants that determines host cellular fate.

Antitumorigenic effect of plumbagin by induction of SH2-containing protein tyrosine phosphatase 1 in human gastric cancer cells

A recent study reported that plumbagin downregulated the activity of Janus kinase 2 (JAK2)-signal transducer and activator of transcription 3 (STAT3) pathway to show various antitumor effects in multiple myeloma cells. We aimed in this in vitro study to demonstrate the inhibition of JAK2/STAT3 pathway by plumbagin through inducing SH2-containing protein tyrosine phosphatase 1 (SHP1) expression in the MKN-28 gastric cancer cell line. We performed western blot analysis to measure SHP1, phosphor-JAK2/STAT3 level, and observed that plumbagin induced SHP1 expression and simultaneously downregulated phosphor-JAK2/STAT3 in MKN-28 cells, with negative SHP1 expression. This effect was consistent when JAK2/STAT3 signaling was activated by interleukin-6 (IL-6), and ameliorated when cells were treated with prevanadate, a protein tyrosin phosphatase inhibitor. Furthermore, plumbagin significantly reduced gene expression of cyclin D1, vascular endothelial growth factor (VEGF)-1, Bcl-xL, survivin and matrix metalloproteinase-9 (MMP-9), known target products of STAT3 activation in gastric carcinogenesis by reverse transcription-polymerase chain reaction (RT-PCR). Several functional studies such as water soluble tetrazolium salt-1 (WST-1) assay, wound closure assay, Matrigel invasion assay and Annexin V assay were also performed, and we validated the functional effect of plumbagin for inhibition of cell proliferation, migration and invasion, and induction of apoptosis. Collectively, our findings suggest that plumbagin is a potential regulator of cellular growth, migration, invasion and apoptosis by inhibiting both constitutive and inducible STAT3 activity through induction of SHP1 in gastric cancer cells.

The regulatory roles of phosphatases in cancer

The relevance of potentially reversible post-translational modifications required for controlling cellular processes in cancer is one of the most thriving arenas of cellular and molecular biology. Any alteration in the balanced equilibrium between kinases and phosphatases may result in development and progression of various diseases, including different types of cancer, though phosphatases are relatively under-studied. Loss of phosphatases such as PTEN (phosphatase and tensin homologue deleted on chromosome 10), a known tumour suppressor, across tumour types lends credence to the development of phosphatidylinositol 3-kinase inhibitors alongside the use of phosphatase expression as a biomarker, though phase 3 trial data are lacking. In this review, we give an updated report on phosphatase dysregulation linked to organ-specific malignancies.

Increased expression of tyrosine phosphatase SHP-2 in Helicobacter pylori-infected gastric cancer

AIM

To explore the alteration of tyrosine phosphatase SHP-2 protein expression in gastric cancer and to assess its prognostic values.

METHODS

Three hundred and five consecutive cases of gastric cancer were enrolled into this study. SHP-2 expression was carried out in 305 gastric cancer specimens, of which 83 were paired adjacent normal gastric mucus samples, using a tissue microarray immunohistochemical method. Correlations were analyzed between expression levels of SHP-2 protein and tumor parameters or clinical outcomes. Serum anti-Helicobacter pylori (H. pylori) immunoglobulin G was detected with enzyme-linked immunosorbent assay. Cox proportional hazards model was used to evaluate prognostic values by compassion of the expression levels of SHP-2 and disease-specific survivals in patients.

RESULTS

SHP-2 staining was found diffuse mainly in the cytoplasm and the weak staining was also observed in the nucleus in gastric mucosa cells. Thirty-two point five percent of normal epithelial specimen and 62.6% of gastric cancer specimen were identified to stain with SHP-2 antibody positively (P < 0.001). Though SHP-2 staining intensities were stronger in the H. pylori (+) group than in the H. pylori (-) group, no statistically significant difference was found in the expression levels of SHP-2 between H. pylori (+) and H. pylori (-) gastric cancer (P = 0.40). The SHP-2 expression in gastric cancer was not significantly associated with cancer stages, lymph node metastases, and distant metastasis of the tumors (P = 0.34, P = 0.17, P = 0.52). Multivariate analysis demonstrated no correlation between SHP-2 expression and disease-free survival (P = 0.86).

CONCLUSION

Increased expression of SHP-2 protein in gastric cancer specimen suggesting the aberrant up-regulation of SHP-2 protein might play an important role in the gastric carcinogenesis.

Helicobacter pylori decreases p27 expression through the delta opioid receptor-mediated inhibition of histone acetylation within the p27 promoter

Chronic Helicobacter pylori infection is associated with the decreased expression of the gastric tumour suppressor protein p27. Because transcription of the gene p27 may be regulated epigenetically through histone acetylation, which is mediated by G-protein coupled delta opioid receptor (DOR) stimulation, we examined whether H. pylori regulates the DOR/histone acetylation/p27 promoter pathway. The levels of acetylated histone and p300, a gene-specific histone acetyltransferase within the p27 promoter, were measured using ChIP assays. The expression of phospho-DOR was evaluated by Western blot and immunohistochemical analyses. Growth curves were constructed, and cell proliferation was assessed after BrdU incorporation. Low p27 expression in acutely H. pylori-infected AGS gastric epithelial cells and in chronically H. pylori-infected AGS-derived HS3C cells was associated with approximate 20% and 40% decreases in p27 mRNA expression, respectively, when compared to p27 mRNA levels in uninfected AGS parental cells. The low p27 mRNA levels following H. pylori infection were associated with a 15-60% reduction in p27 promoter histone H4 acetylation. The recruitment of p300 to the p27 promoter was also markedly decreased by H. pylori infection. The expression of phospho-DOR was decreased by H. pylori infection in cell lines in vitro and in H. pylori-infected human gastric mucosa in vivo. The level of cellular p27 inversely correlated with cell proliferation in HS3C cells. These results demonstrate that H. pylori decreases p27 expression by modulating the DOR and thereby inhibiting histone acetylation of the p27 promoter. These findings link low gastric p27 expression levels with increased instances of gastric carcinogenesis associated with H. pylori infection.

Association of polymorphism of PTPN 11 encoding SHP-2 with gastric atrophy but not gastric cancer in Helicobacter pylori seropositive Chinese population

BACKGROUND

The interaction between Src homology 2 domain-containing protein tyrosine phosphatase (SHP-2) of gastric epithelial cells and cagA from H. pylori plays a crucial role in developments of gastric atrophy and gastric cancer. This study aimed to investigate the association of haplotype tagging SNPs (htSNPs) in the PTPN11 gene encoding SHP-2 with gastric atrophy and gastric cancer in Chinese population.

METHODS

The subjects comprised 414 patients with gastric cancer, 109 individuals with gastric atrophy and 923 healthy controls. Blood was collected from October 2008 to October 2010. Five htSNPs rs2301756, rs12423190, rs12229892, rs7958372 and rs4767860 from the PTPN11 gene were selected and genotyped by Taqman assay. Serum Ig G antibodies to H. pylori were detected by ELISA. Gastric atrophy was screened by the levels of serum pepsinogenIandII, and confirmed by endoscopy and histopatholgical examinations. Odds ratio (ORs) and 95% confidence intervals (CIs) were calculated by a multivariate logistic regression.

RESULTS

Among H. pylori seropositive subjects, age and gender-adjusted OR of gastric atrophy was 2.47 (95%CI 1.13-4.55, P = 0.02) for CC genotype compared with CT/TT genotypes, suggesting a recessive model of genetic risk for rs12423190. The prevalence of H. pylori seropositivity were significantly higher in groups of gastric cancer and gastric atrophy compared to the control group (70.3% vs. 75.2% vs. 49.7%, P <0.001). However, the distributions of genotypes and haplotypes in patients with gastric cancer were not significantly different from healthy controls.

CONCLUSIONS

Our study provides the first evidence that rs12423190 polymorphism of the PTPN11 gene is significantly associated with an increased risk of gastric atrophy in H. pylori infected Chinese Han population, suggesting that rs12423190 polymorphism could be used as a useful marker of genetic susceptibility to gastric atrophy among H. pylori infected subjects. The biological roles of this polymorphism require a further investigation.

The tumor suppressor role of Src homology phosphotyrosine phosphatase 2 in hepatocellular carcinoma

PURPOSE

The human gene PTPN11, which encodes the non-receptor protein tyrosine phosphatase of Src homology phosphotyrosine phosphatase 2 (Shp2), has been previously well interpreted as a proto-oncogene in a variety of malignancies. However, the tumor suppressor role of Shp2 has also been reported. The present study was conducted to investigate the role of Shp2 expression and its associated clinical manifestations in hepatocellular carcinoma (HCC).

METHODS

A tissue microarray of 333 pairs of HCC and self-matched adjacent non-tumor tissues was constructed, and the expression of Shp2 was determined by immunohistochemistry. The results were also conformed by Western blotting and quantitative PCR of 31 self-paired fresh HCC specimens. The associations of Shp2 expression with 25 clinicopathologic features were analyzed. Overall survival analysis and multivariate analysis were performed.

RESULTS

Significantly decreased Shp2 expression in tumor tissues (T) compared with adjacent non-tumor tissues (NT) could be detected, and the positive rate was 66.1 and 96.7%, respectively. We combined the T and NT Shp2 immunoreactivity by a variable of the decrease in Shp2 expression (ΔShp2) and divided cases into 2 groups: T < NT and T ≥ NT. Survival analysis showed both low Shp2 expression and T < NT group were significantly associated with short overall survival. Multivariate analysis showed ΔShp2 was an independent prognostic marker (P = 0.033; HR: 0.527; 95% CI: 0.293-0.950).

CONCLUSION

Shp2 is a tumor suppressor, and the decrease in Shp2 expression was a new prognostic marker in HCC. The oncogenic role of Shp2 was tissue specific, and the therapeutic target of human gene PTPN11 should be reconsidered.