Expressions of urokinase-type plasminogen activator, its receptor and plasminogen activator inhibitor-1 in gastric cancer cells and effects of Helicobacter pylori

Expression of Serpin Family E Member 1 (SERPINE1) Is Associated with Poor Prognosis of Gastric Adenocarcinoma

BACKGROUND

The aberrant expression of serpin family E member 1 (SERPINE1) is associated with carcinogenesis. This study assessed the alteration of SERPINE1 expression for an association with gastric adenocarcinoma prognosis.

METHODS

The Cancer Genome Atlas (TCGA) dataset was applied to investigate the impact of SERPINE1 expression on the survival of patients afflicted with gastric cancer. Subsequently, 136 samples from the Affiliated Huaian No. 1 People's Hospital of Nanjing Medical University were subjected to qRT-PCR and Western blot to validate the expression level of SERPINE1 between tumor and adjacent normal tissues. The correlation between the expression of SERPINE1 with the clinicopathological features in TCGA patients was analyzed using Wilcoxon signed-rank and logistic regression tests. The potential molecular mechanism associated with SERPINE1 expression in gastric cancer were confirmed using gene set enrichment analysis (GSEA).

RESULTS

The TCGA data showed that SERPINE1 was overexpressed in tumor tissues compared to normal mucosae and associated with the tumor T stage and pathological grade. SERPINE1 overexpression was associated with the poor overall survival (OS) of patients. The findings were confirmed with 136 patients, that is, SERPINE1 expression was associated with poor OS (hazard ratio (HR): 1.82; 95% confidence interval (CI): 0.84-1.83; p = 0.012)) as an independent predictor (HR: 2.11, 95% CI: 0.81-2.34; p = 0.009). The resulting data were further processed by GSEA showed that SERPINE1 overexpression was associated with the activation of EPITHELIAL_MESENCHYMAL_TRANSITION, TNFA_SIGNALING_VIA_NFKB, INFLAMMATORY_RESPONSE, ANGIOGENESIS, and HYPOXIA.

CONCLUSIONS

SERPINE1 overexpression is associated with a poor gastric cancer prognosis.

Helicobacter pylori Colonization Drives Urokinase Receptor (uPAR) Expression in Murine Gastric Epithelium During Early Pathogenesis

(1) Background: Persistent Helicobacter pylori infection is the most important risk factor for gastric cancer. The urokinase receptor (uPAR) is upregulated in lesions harboring cancer invasion and inflammation. Circumstantial evidence tends to correlate H. pylori colonization with increased uPAR expression in the human gastric epithelium, but a direct causative link has not yet been established in vivo; (2) Methods: In a mouse model of H. pylori-induced gastritis, we investigated the temporal emergence of uPAR protein expression in the gastric mucosa in response to H. pylori (SS1 strain) infection; (3) Results: We observed intense uPAR immunoreactivity in foveolar epithelial cells of the gastric corpus due to de novo synthesis, compared to non-infected animals. This uPAR induction represents a very early response, but it increases progressively over time as do infiltrating immune cells. Eradication of H. pylori infection by antimicrobial therapy causes a regression of uPAR expression to its physiological baseline levels. Suppression of the inflammatory response by prostaglandin E₂ treatment attenuates uPAR expression. Notwithstanding this relationship, H. pylori does induce uPAR expression in vitro in co-cultures with gastric cancer cell lines; (4) Conclusions: We showed that persistent H. pylori colonization is a necessary event for the emergence of a relatively high uPAR protein expression in murine gastric epithelial cells.

N-terminal region of Helicobacter pylori CagA induces IL-8 production in gastric epithelial cells via the β1 integrin receptor

Introduction. Helicobacter pylori is associated with gastrointestinal disease, most notably gastric cancer. Cytotoxin-associated antigen A (CagA), an important virulence factor for H. pylori pathogenicity, induces host cells to release inflammatory factors, especially interleukin-8 (IL-8). The mechanism by which C-terminal CagA induces IL-8 production has been studied extensively, but little is known about the role of the N-terminus.

Aim. To investigate the effect of CagA303–456aa (a peptide in the N-terminal CagA) on IL-8 production by gastric epithelial cells.

Methodology. CagA303-456aa was produced by a prokaryotic expression system and purified by Strep-tag affinity chromatography. An integrin β1 (ITGB1)-deficient AGS cell line was constructed using the CRISPR/Cas9 technique, and NCTC 11637 cagA and/or cagL knockout mutants were constructed via homologous recombination. The levels of IL-8 production were determined by enzyme-linked immunosorbent assay (ELISA), and p38 and ERK1/2 phosphorylation were examined by Western blot.

Results. CagA303-456aa induced IL-8 expression by AGS cells. IL-8 induction by CagA303-456aawas specifically inhibited by ITGB1 deficiency. Notably, CagA303-456aa activated the phosphorylation of both p38 and ERK1/2, and blocking p38 and ERK1/2 activity significantly reduced IL-8 induction by CagA303-456aa. ITGB1 deficiency also inhibited the activation of p38 phosphorylation by CagA303-456aa. Finally, experiments in CagA and/or CagL knockout bacterial lines demonstrated that extracellular CagA might induce IL-8 production by AGS cells.

Conclusion. Residues 303–456 of the N-terminal region of CagA induce IL-8 production via a CagA303-456–ITGB1–p38–IL-8 pathway, and ERK1/2 is also involved in the release of IL-8. Extracellular CagA might induce IL-8 production before translocation into AGS cells.

Proteolysis is the most fundamental property of malignancy and its inhibition may be used therapeutically (Review)

The mortality rates of cancer patients decreased by ~1.5% per year between 2001 and 2015, although the decrease depends on patient sex, ethnic group and type of malignancy. Cancer remains a significant global health problem, requiring a search for novel treatments. The most common property of malignant tumors is their capacity to invade adjacent tissue and to metastasize, and this cancer aggressiveness is contingent on overexpression of proteolytic enzymes. The components of the plasminogen activation system (PAS) and the metal-loproteinase family [mainly matrix metalloproteinases (MMPs)] are overexpressed in malignant tumors, driving the local invasion, metastasis and angiogenesis. This is the case for numerous types of cancer, such as breast, colon, prostate and oral carcinoma, among others. Present chemotherapeutics agents typically attack all dividing cells; however, for future therapeutic agents to be clinically successful, they need to be highly selective for a specific protein(s) and act on the cancerous tissues without adverse systemic effects. Inhibition of proteolysis in cancerous tissue has the ability to attenuate tumor invasion, angiogenesis and migration. For that purpose, inhibiting both PAS and MMPs may be another approach, since the two groups of enzymes are overexpressed in cancer. In the present review, the roles and new findings on PAS and MMP families in cancer formation, growth and possible treatments are discussed.

Priming the seed: Helicobacter pylori alters epithelial cell invasiveness in early gastric carcinogenesis

Helicobacter pylori (H. pylori) infection is a well-established risk factor for the development of gastric cancer (GC), one of the most common and deadliest neoplasms worldwide. H. pylori infection induces chronic inflammation in the gastric mucosa that, in the absence of treatment, may progress through a series of steps to GC. GC is only one of several clinical outcomes associated with this bacterial infection, which may be at least partially attributed to the high genetic variability of H. pylori. The biological mechanisms underlying how and under what circumstances H. pylori alters normal physiological processes remain enigmatic. A key aspect of carcinogenesis is the acquisition of traits that equip preneoplastic cells with the ability to invade. Accumulating evidence implicates H. pylori in the manipulation of cellular and molecular programs that are crucial for conferring cells with invasive capabilities. We present here an overview of the main findings about the involvement of H. pylori in the acquisition of cell invasive behavior, specifically focusing on the epithelial-to-mesenchymal transition, changes in cell polarity, and deregulation of molecules that control extracellular matrix remodeling.

Tanshinone II-A Inhibits Invasion and Metastasis of Human Hepatocellular Carcinoma Cells in Vitro and in Vivo

Aims and Background

Tanshinone II-A is an alcohol extract of the root of the traditional Chinese medicinal plant Salvia miltiorrhiza Bunge, whose effects and mechanism in tumor metastasis are still unclear. The aim of this study was to investigate the effects of tanshinone II-A on tumor invasion and metastasis in human hepatocellular carcinoma (HCC) and its possible mechanism of action.

Methods and Study Design

The HCC cell lines HepG2 and SMMC-7721 were treated with tanshinone II-A at different doses. Invasion and metastasis of tumor cells were examined by in vitro and in vivo assays. The molecular mechanisms of tanshinone II-A for inhibiting invasion and metastasis of HCC cells were investigated by Western blot and gelatin zymography.

Results

Treatment with tanshinone II-A had inhibitory effects on the migration and invasion of HCC cells. Increasing doses resulted in enhanced inhibitory effects. At 0.5 mg/L, the inhibitory effect was noticeable. At 1 mg/L, the inhibitory rate was 53.15%. The inhibitory effect became stronger with time; among 24, 48, 72 and 96 hours of treatment, the most significant effects were observed at 72 hours. Tanshinone II-A also significantly inhibited in vivo metastasis of HepG2 cells. Tanshinone II-A inhibited in vitro and in vivo invasion and metastasis of HCC cells by reducing the expression of the metalloproteinases MMP2 and MMP9 and by blocking NF-kappa B activation.

Conclusions

Tanshinone II-A effectively inhibited invasion and metastasis of HCC cells in vitro and in vivo, partly by inhibiting the activity of MMP2 and MMP9, and partly via the NF-kappa B signal transduction pathway.

Correlation of Helicobacter pylori and interleukin-8 mRNA expression in high risk gastric cancer population prediction

AIM: To evaluate (1) the association of the Helicobacter pylori (H. pylori) test and interleukin-8 (IL-8) mRNA expression alone and the severity of gastric cancer (GC); (2) the association of both tests were added to patients' characteristics to identifli Thai suspected patients of gastric cancer who would receive the most benefit; and (3) diagnostic value of levels of IL-8 mRNA expression for gastric cancer.

METHODS: A cross-sectional analytical study was completed with 220 patients with 86 GC patients who underwent endoscopy with gastric surgery divided into non-metastasis and metastasis groups, and 134 patients with benign lesions who underwent endoscopic examination, at the Gastrointestinal Surgery and Endoscopy Unit, Chiang Mai University Hospital between 2006 and 2010. Of 220 patients, 86 cases of diagnosed gastric adenocarcinoma were in an advanced stage and 134 cases were non-cancer patients.

RESULTS: The IL-8 mRNA expression showed predominant association with advanced GC when compared to H. pylori infection alone [OR (95%CI); 0.86 (0.49-1.53) vs 5.44 (3.08-9.62)] when including the patients’ characteristics the highest of the area under the receiver operating characteristic curves (AuROC) of the model were males older than 40 years of age [AuROC (95%CI); 0.81 (0.75-0.86)]. However, preliminary testing for diagnostic indices of four cut-off points of IL-8 mRNA expression to predict the severity of GC cases found an increasing suboptimal trend from the likelihood ratio of positive to differentiate the severity in the GC group. The IL-8 mRNA expression showed a predominant association with GC when compared to H. pylori infection, especially in males older than 40 years of age who may benefit most from this test.

CONCLUSION: The future research of IL-8 mRNA expression to predict severity in the gastric cancer group should be warranted.

Helicobacter pylori-induced inflammation and epigenetic changes during gastric carcinogenesis

The sequence of events associated with the development of gastric cancer has been described as “the gastric precancerous cascade”. This cascade is a dynamic process that includes lesions, such as atrophic gastritis, intestinal metaplasia and dysplasia. According to this model, Helicobacter pylori (H. pylori) infection targets the normal gastric mucosa causing non-atrophic gastritis, an initiating lesion that can be cured by clearing H. pylori with antibiotics or that may then linger in the case of chronic infection and progress to atrophic gastritis. The presence of virulence factors in the infecting H. pylori drives the carcinogenesis process. Independent epidemiological and animal studies have confirmed the sequential progression of these precancerous lesions. Particularly long-term follow-up studies estimated a risk of 0.1% for atrophic gastritis/intestinal metaplasia and 6% in case of dysplasia for the long-term development of gastric cancer. With this in mind, a better understanding of the genetic and epigenetic changes associated with progression of the cascade is critical in determining the risk of gastric cancer associated with H. pylori infection. In this review, we will summarize some of the most relevant mechanisms and focus predominantly but not exclusively on the discussion of gene promoter methylation and miRNAs in this context.

Impact of proteolytic enzymes in colorectal cancer development and progression

Tumor invasion and metastasis is a highly complicated, multi-step phenomenon. In the complex event of tumor progression, tumor cells interact with basement membrane and extracellular matrix components. Proteolytic enzymes (proteinases) are involved in the degradation of extracellular matrix, but also in cancer invasion and metastasis. The four categories of proteinases (cysteine-, serine-, aspartic-, and metalloproteinases) are named and classified according to the essential catalytic component in their active site. We and others have shown that proteolytic enzymes play a major role not only in colorectal cancer (CRC) invasion and metastasis, but also in malignant transformation of precancerous lesions into cancer. Tissue and serum-plasma antigen concentrations of proteinases might be of great value in identifying patients with poor prognosis in CRC. Our results, in concordance with others indicate the potential tumor marker impact of proteinases for the early diagnosis of CRC. In addition, proteinases may also serve as potential target molecules for therapeutic agents.

Helicobacter pylori and interleukin-8 in gastric cancer

Helicobacter pylori (H. pylori) is a major etiological factor in the development of gastric cancer. Large-scale epidemiological studies have confirmed the strong association between H. pylori infection and both cancer development and progression. Interleukin-8 (IL-8) is overexpressed in gastric mucosa exposed to H. pylori. The expression of IL-8 directly correlates with a poor prognosis in gastric cancer. IL-8 is multifunctional. In addition to its potent chemotactic activity, it can induce proliferation and migration of cancer cells. In this review, we focus on recent insights into the mechanisms of IL-8 signaling associated with gastric cancer. The relationship between IL-8 and H. pylori is discussed. We also summarize the current therapeutics against IL-8 in gastric cancer.

Role of urokinase plasminogen activator receptor in gastric cancer: a potential therapeutic target

Recent advancements in cancer research have led to major breakthroughs; however, the impact on overall cancer-related death rate remains unacceptable. Thus, further insights into tumor markers and subsequent development of targeted therapies are urgently needed. For decades the urokinase plasminogen activator (uPA) system has been thought to drive tumor progression by mediating directed extracellular proteolysis on the surface of migrating or invading cells. Intervention with this proteolysis by targeting of uPA receptor (uPAR) has been proposed to represent a novel approach for inhibiting tumor progression. Recent data have provided new insights into the role of uPAR in gastric cancer progression. In addition to mediating proteolysis, this receptor also appears to mediate cell signaling, proliferation, and survival, and these observations have revealed novel ways to target uPAR. In this review, we discuss uPAR expression in gastric cancer, the relationship between uPAR and Helicobacter pylori, and recent insights into uPAR-signaling mechanisms. The role of uPAR as a cancer target in gastric cancer is also summarized.

Induction of brain microvascular endothelial cell urokinase expression by Cryptococcus neoformans facilitates blood-brain barrier invasion

The invasive ability of the blood-borne fungal pathogen Cryptococcus neoformans can be enhanced through interactions with host plasma components, such as plasminogen. Previously we showed by in vitro studies that plasminogen coats the surface of C. neoformans and is converted to the active serine protease, plasmin, by host plasminogen activators. Viable, but not formaldehyde- or sodium azide-killed, cryptococcal strains undergo brain microvascular endothelial cell-dependent plasminogen-to-plasmin activation, which results in enhanced, plasmin-dependent cryptococcal invasion of primary bovine brain microvascular endothelial cells and fungal ability to degrade plasmin substrates. In the present work, brain microvascular endothelial cells cultured with viable, but not killed, cryptococcal strains led to significant increases in both urokinase mRNA transcription and cell-associated urokinase protein expression. Soluble urokinase was also detected in conditioned medium from brain microvascular endothelial cells cultured with viable, but not killed, C. neoformans. Exposure of plasminogen pre-coated viable C. neoformans to conditioned medium from strain-matched brain microvascular endothelial cell-fungal co-cultures resulted in plasminogen-to-plasmin activation and plasmin-dependent cryptococcal invasion. siRNA-mediated silencing of urokinase gene expression or the use of specific inhibitors of urokinase activity abrogated both plasminogen-to-plasmin activation on C. neoformans and cryptococcal-brain microvascular endothelial cell invasion. Our results suggest that pathogen exploitation of the host urokinase-plasmin(ogen) system may contribute to C. neoformans virulence during invasive cryptococcosis.

Putative tumor metastasis-associated genes in human gastric cancer

Gastric cancer is one of the leading causes of cancer mortality and its malignancy, resulting from disseminated cancer cells of diffuse type, is clinically manifested as metastases to the liver and peritoneum. The aim of the present study was to identify putative tumor metastasis-associated genes in human gastric cancer cells of diffuse type. An MKN45 cell line constitutively expressing green fluorescent protein (MKN45-GFP) was established and selected using the Transwell® system for invasive sublines MKN45-GFP-4, MKN45-GFP-10 and MKN45-GFP-12. MKN45-GFP-10 and MKN45-GFP-12 are highly invasive compared to the others. The mRNA levels were measured with cDNA microarrays and correlated with their invasion abilities in these sublines. Many of the genes identified with a positive or negative correlation are associated with angiogenesis, cell cycle, cytoskeleton and cell motility, protease and cell adhesion, as well as cellular signal transduction. In particular, novel genes without known functions were also noted. RT-PCR and western blot analyses were applied to verify the expression of selective genes. Following orthotopical intraperitoneal implantation, MKN45-GFP-12 demonstrated significantly higher in vivo tumor malignancies than parental MKN45-GFP in ascites induction and liver -invasion in mice. We have identified putative gastric tumor metastasis-associated, as well as novel genes. These genes and their protein products are to be further explored for their functional roles associated with tumor metastasis. The molecular profiles of these identified genes, gene transcripts and proteins in the patient specimens are likely to be useful biomarkers for diagnostic, therapeutic and/or prognostics. Most importantly, they may be used as molecular targets for the discovery of antitumor drugs against human gastric cancer metastasis.

Ardipusilloside inhibits survival, invasion and metastasis of human hepatocellular carcinoma cells

ETHNOPHARMACOLOGICAL RELEVANCE

Ardipusilloside I is a triterpene-saponin isolated from the Traditional Chinese Medicine Ardisia pusilla A. DC. Its effects and mechanism on invasion and metastasis of liver cancer cells are unclear.

MATERIALS AND METHODS

The human hepatocellular carcinoma cell line HepG2 and SMMC-7721 cells were treated with different doses of Ardipusilloside I. Cellular survival, in vitro migration and invasion were evaluated. In vivo metastatic abilities of the HCC cells were detected. We further investigated expression and phosphorylation of Mek, Erk and Akt by using Western blot. MMP2 and MMP9 activities were evaluated by gelatin zymography. E-cadherin expression, Rac1 and Cdc42 activities were examined by Western blot and pull-down assay.

RESULTS

Ardipusilloside I inhibited invasion and metastasis of HCC cells both in vitro and in vivo by reducing the protein expressions of metalloproteinase (MMP)-9 and MMP2 proteins. Ardipusilloside I activated Rac1 that enhanced E-cadherin activity and resulted in significantly less metastasis.

CONCLUSION

Our findings indicate that Ardipusilloside I has the potential of inhibition of liver cancer survival, invasion and metastasis both in vitro and in vivo.

ARNTL2 and SERPINE1: potential biomarkers for tumor aggressiveness in colorectal cancer

PURPOSE

Cathepsin and plasmin may favor cancer cell invasion degrading extracellular matrix. Plasmin formation from plasminogen is regulated by plasminogen activator inhibitor type-1 (PAI-1). ARNTL2 activates the promoters of the PAI-1 gene, officially called SERPINE1, driving the circadian variation in circulating PAI-1 levels.

METHODS

We evaluated ARNTL2 and SERPINE1 expression in 50 colorectal cancer specimens and adjacent normal tissue and in colon cancer cell lines.

RESULTS

We found up-regulation of ARNTL2 (P = 0.004) and SERPINE1 (P = 0.002) in tumor tissue. A statistically significant association was found between high ARNTL2 mRNA levels and vascular invasion (P < 0.0001), and between high SERPINE1 mRNA levels and microsatellite instability (MSI-H and MSI-L, P = 0.025). Sorting the subjects into quartile groups, a statistically significant association was found between high ARNTL2 expression and lymph node involvement (P < 0.001), between high SERPINE1 expression and grading (P < 0.001) and between high SERPINE1 expression and MSI H-L (P < 0.0001). In SW480 cells, a more proliferative model compared to CaCo2 cells, there were higher mRNA levels of ARNTL2 (P < 0.001) and SERPINE1 (P = 0.001).

CONCLUSION

ARNTL2 and SERPINE1 expression is increased in colorectal cancer and in a highly proliferative colon cancer cell line and is related to tumor invasiveness and aggressiveness.

Artemisinin inhibits in vitro and in vivo invasion and metastasis of human hepatocellular carcinoma cells

Artemisinin (ART) is isolated from the medicinal plant Artemisia annua L. To determine its effects on the invasion and metastasis of tumors, the human hepatocellular carcinoma (HCC) cell lines HepG2 and SMMC-7721 were treated with different concentrations of ART. Starting at 12.5μM, ART had inhibitory effects in migration and invasion assays that increased at higher concentrations. The inhibitory effect also became stronger with time, from 24 to 72h. ART significantly inhibited the in vivo metastatic abilities of the HepG2 HCC cell line. ART inhibited the invasion and metastasis of HCC cells both in vitro and in vivo by reducing the level of the MMP2 metalloproteinase, and by inducing the TIMP2 protein. ART activated Cdc42, which enhanced E-cadherin activity, resulting in greater cell-cell adhesion, and significantly reduced metastasis.

Involvement of tumor necrosis factor-alpha in the upregulation of CXCR4 expression in gastric cancer induced by Helicobacter pylori

Background

H. pylori, whose infection increases tumor invasiveness and metastasis, is generally labelled as the strongest risk factor for the development of gastric cancer. It appears not to be a coincidence that there is also an overexpression of CXCR4 and an obvious involvement in gastric cancer metastasis. The aim of this study attempts to investigate and further to establish a link between them. With H. pylori being a potent inducer of TNF-α, whether TNF-α, a tumor promoter, is involved in the induction of CXCR4 expression by H. pylori was also under research in this study.

Methods

Expression of CXCR4, TNF-α, IL-6 and IL-1β mRNA was determined by real-time PCR. CXCR4 protein expression was detected by Western blotting. Concentrations of TNF-α, IL-6 and IL-1β in cell culture supernatants were measured using the Quantikine Elisa kit. To abrogate TNF-α expression in HGC27 cells, TNF-α RNAi plasmid was used to transfect them.

Results

Levels of CXCR4 and TNF-α mRNA were significantly higher in H. pylori-positive gastric cancers (n = 19) compared to H. pylori-negative ones (n = 15). A subsequently Spearman's rank correlation test showed there was a positive correlation between the level of CXCR4 mRNA and that of TNF-α in 34 primary gastric cancers. Other results followed: Expression of CXCR4 and TNF-α was upregulated in gastric cancer cell MKN45 and HGC27 after infection with H. pylori 26695 (cag PAI⁺ ) or Tx30a (cag PAI^- ); The induction of CXCR4 expression by H. pylori was inhibited significantly by a neutralizing TNF-α antibody, infliximab; CXCR4 expression was upregulated in MKN45 cells after treatment with exogenous TNF-α or co-culture with macrophage, and was downregulated in HGC27 cells after transfection with TNF-α RNAi plasmid. There was a significant increase in the migration of MKN45 cells treated with H. pylori 26695, and a strong inhibition when AMD 3100, a CXCR4 antagonist, or infliximab, was added.

Conclusions

Our findings demonstrated that H. pylori upregulates CXCR4 expression in gastric cancer through TNF-α.

Urokinase plasminogen activator receptor is expressed in invasive cells in gastric carcinomas from high- and low-risk countries

Gastric cancer is the second cancer causing death worldwide. Both incidence and mortality rates vary according to geographical regions. The receptor for urokinase plasminogen activator (uPAR) is involved in extracellular matrix degradation by mediating cell surface associated plasminogen activation, and its presence on gastric cancer cells is linked to micro-metastasis and poor prognosis. Immunohistochemical analyses of a set of 44 gastric cancer lesions from Costa Rica showed expression of uPAR in cancer cells in both intestinal subtype (14 of 27) and diffuse subtype (10 of 17). We compared the expression pattern of uPAR in gastric cancers from a high-risk country (Costa Rica) with a low-risk country (Norway). We found uPAR on gastric cancer cells in 24 of 44 cases (54%) from Costa Rica and in 13 of 23 cases (56%) from Norway. uPAR was seen in macrophages and neutrophils in all cases. We also examined the nonneoplastic mucosa and found that uPAR was more frequently seen in epithelial cells located at the luminal edge of the crypts in cases with Helicobacter pylori infection than in similar epithelial cells in noninfected mucosa (p = 0.033; chi(2) = 4.54). In conclusion, the expression of uPAR in cancer cells in more than half of the gastric cancer cases suggests that their uPAR-positivity do not contribute to explain the different mortality rates between the 2 countries, however, the actual prevalence of uPAR-positive cancer cells in the gastric cancers may still provide prognostic information.

Hepatocellular carcinoma: prevalence and molecular pathogenesis of Helicobacter spp

Helicobacter pylori infection is one of the most common chronic bacterial infections in humans. The association of other Helicobacter spp. with extragastric diseases in animals is well established, and a role of these bacteria in human liver disease is becoming clearer. Several case-control studies have reported possible associations of Helicobacter spp. with various liver diseases, including hepatocellular carcinoma, which is the fifth most common type of carcinoma among men worldwide, and the eighth most common among women. Thus, it is important to understand molecular mechanisms that may lead to hepatotoxicity or hepatocellular dysfunction in which Helicobacter spp. may play a role in inducing malignant transformation of liver cells.

Inhibitory effects of tanshinone II-A on invasion and metastasis of human colon carcinoma cells

AIM

To investigate the effects and possible mechanisms of tanshinone II-A, an alcohol extract of the root of Salvia miltiorrhiza Bunge, on tumor invasion and metastasis of human colon carcinoma (CRC) cells.

METHODS

The effects of tanshinone II-A on invasion and metastasis of CRC cell lines HT29 and SW480 were evaluated by in vitro and in vivo assays. Western blotting was used to investigate possible molecular mechanisms of tanshinone II-A anti-cancer actions.

RESULTS

Tanshinone II-A inhibited migration and invasion of CRC cells in a dose-dependent manner. The inhibitory effect also depended on time, with the most significant effects observed at 72 h. Tanshinone II-A also significantly inhibited in vivo metastasis of colon carcinoma SW480 cells. It inhibited in vitro and in vivo invasion and metastasis of CRC cells by reducing levels of urokinase plasminogen activator (uPA) and matrix metalloproteinases (MMP)-2 and MMP-9, and by increasing levels of tissue inhibitor of matrix metalloproteinase protein (TIMP)-1 and TIMP-2. Tanshinone II-A was also shown to suppress the nuclear factor-kappaB (NF-kappaB) signal.

CONCLUSION

Tanshinone II-A inhibited in vitro and in vivo invasion and metastasis of CRC cells. The effect resulted from changes in the levels of uPA, MMP-2, MMP-9, TIMP-1 and TIMP-2, and apparent inhibition of the NF-kappaB signal transduction pathway.

Serum cathepsin B and plasma urokinase-type plasminogen activator levels in gastrointestinal tract cancers

Cathepsin B (CATB) and urokinase-type plasminogen activator (UPA) play an important part in cancer invasion and metastasis. The behavior of CATB and UPA has not been evaluated in the same experimental setting in different gastrointestinal tumors and in precancerous lesions. Serum CATB and plasma UPA levels were determined by enzyme-linked immunoadsorbent assay and their sensitivity, specificity, and diagnostic accuracy have been calculated in patients with colorectal (n=72), gastric (n=30), hepatocellular (n=28), and pancreatic cancer (n=15) as well as in gastric epithelial dysplasia (n=25), colorectal adenomas (n=30), and tumor-free control patients (n=44). Serum CATB and plasma UPA antigen concentrations were significantly higher in patients with cancer than in controls. When all tumors were considered, the sensitivity, specificity, and diagnostic accuracy of CATB (89, 86, and 89%) were higher than that of UPA (76, 70, and 74%). CATB demonstrated in all types of tumors a better diagnostic accuracy than UPA. The positive predictive values of CATB (95%) and UPA (89%) may suggest their use in the evaluation of patients with a suspicion of malignancy. CATB and UPA were significantly higher in patients with gastric epithelial dysplasia and colorectal adenomas than in controls. Antigen levels of CATB and UPA were significantly correlated in both cancers and precancerous lesions. At the time of clinical presentation, serum CATB and plasma UPA antigen levels are sensitive indicators of gastrointestinal malignancies. Determination of serum CATB and plasma UPA levels may be useful to identify patients at a higher risk for progression to cancer, who could be subjected to a more strict follow-up protocol.

Increased expression of the urokinase plasminogen activator system by Helicobacter pylori in gastric epithelial cells

The gastric pathogen Helicobacter pylori (H. pylori) is linked to peptic ulcer and gastric cancer, but the relevant pathophysiological mechanisms are unclear. We now report that H. pylori stimulates the expression of plasminogen activator inhibitor (PAI)-1, urokinase plasminogen activator (uPA), and its receptor (uPAR) in gastric epithelial cells and the consequences for epithelial cell proliferation. Real-time PCR of biopsies from gastric corpus, but not antrum, showed significantly increased PAI-1, uPA, and uPAR in H. pylori-positive patients. Transfection of primary human gastric epithelial cells with uPA, PAI-1, or uPAR promoters in luciferase reporter constructs revealed expression of all three in H+/K+ATPase- and vesicular monoamine transporter 2-expressing cells; uPA was also expressed in pepsinogen- and uPAR-containing trefoil peptide-1-expressing cells. In each case expression was increased in response to H. pylori and for uPA, but not PAI-1 or uPAR, required the virulence factor CagE. H. pylori also stimulated soluble and cell surface-bound uPA activity, and both were further increased by PAI-1 knockdown, consistent with PAI-1 inhibition of endogenous uPA. H. pylori stimulated epithelial cell proliferation, which was inhibited by uPA immunoneutralization and uPAR knockdown; exogenous uPA also stimulated proliferation that was further increased after PAI-1 knockdown. The proliferative effects of uPA were inhibited by immunoneutralization of the EGF receptor and of heparin-binding EGF (HB-EGF) by the mutant diphtheria toxin CRM197 and an EGF receptor tyrosine kinase inhibitor. H. pylori induction of uPA therefore leads to epithelial proliferation through activation of HB-EGF and is normally inhibited by concomitant induction of PAI-1; treatments directed at inhibition of uPA may slow the progression to gastric cancer.

Tumor marker utility and prognostic relevance of cathepsin B, cathepsin L, urokinase-type plasminogen activator, plasminogen activator inhibitor type-1, CEA and CA 19-9 in colorectal cancer

BACKGROUND

Cathepsin B and L (CATB, CATL), urokinase-type plasminogen activator (uPA) and its inhibitor PAI-1 play an important role in colorectal cancer invasion. The tumor marker utility and prognostic relevance of these proteases have not been evaluated in the same experimental setting and compared with that of CEA and CA-19-9.

METHODS

Protease, CEA and CA 19-9 serum or plasma levels were determined in 56 patients with colorectal cancer, 25 patients with ulcerative colitis, 26 patients with colorectal adenomas and 35 tumor-free control patients. Protease, CEA, CA 19-9 levels have been determined by ELISA and electrochemiluminescence immunoassay, respectively; their sensitivity, specificity, diagnostic accuracy have been calculated and correlated with clinicopathological staging.

RESULTS

The protease antigen levels were significantly higher in colorectal cancer compared with other groups. Sensitivity of PAI-1 (94%), CATB (82%), uPA (69%), CATL (41%) were higher than those of CEA or CA 19-9 (30% and 18%, respectively). PAI-1, CATB and uPA demonstrated a better accuracy than CEA or CA 19-9. A combination of PAI-1 with CATB or uPA exhibited the highest sensitivity value (98%). High CATB, PAI-1, CEA and CA 19-9 levels correlated with advanced Dukes stages. CATB (P = 0.0004), CATL (P = 0.02), PAI-1 (P = 0.01) and CA 19-9 (P = 0.004) had a significant prognostic impact. PAI-1 (P = 0.001), CATB (P = 0.04) and CA 19-9 (P = 0.02) proved as independent prognostic variables.

CONCLUSION

At the time of clinical detection proteases are more sensitive indicators for colorectal cancer than the commonly used tumor markers. Determinations of CATB, CATL and PAI-1 have a major prognostic impact in patients with colorectal cancer.

Helicobacter pylori infection stimulates plasminogen activator inhibitor 1 production by gastric epithelial cells

Chronic infection with the gastric pathogen Helicobacter pylori significantly increases the risk of developing atrophic gastritis, peptic ulcer disease, and gastric adenocarcinoma. H. pylori strains that possess the cag pathogenicity island, which translocates CagA into the host cells, augment these risks. The aim of this study was to determine the molecular mechanisms through which H. pylori upregulates the expression of plasminogen activator inhibitor 1 (PAI-1), a member of the urokinase activator system that is involved in tumor metastasis and angiogenesis. Levels of PAI-1 mRNA and protein were examined in tissues from H. pylori-infected patients and in vitro using AGS gastric epithelial cells. In vitro, cells were infected with toxigenic cag-positive or nontoxigenic cag-negative strains of H. pylori or isogenic mutants. The amount of PAI-1 secretion was measured by enzyme-linked immunosorbent assay, and mRNA levels were determined using real-time PCR. The regulation of PAI-1 was examined using the extracellular signal-regulated kinase 1/2 (ERK1/2) inhibitor and small interfering RNA. Analysis of human biopsy samples revealed an increase in both PAI-1 mRNA and protein levels in patients with H. pylori gastritis compared to those of uninfected controls. Infection of AGS cells with H. pylori significantly increased PAI-1 mRNA expression and the secretion of PAI-1 protein. Moreover, PAI-1 mRNA and protein production was more pronounced when AGS cells were infected by H. pylori strains carrying a functional cag secretion system than when cells were infected by strains lacking this system. PAI-1 secretion was also reduced when cells were infected with either cagE-negative or cagA-negative mutants. The ectopic overexpression of CagA significantly increased the levels of PAI-1 mRNA and protein, whereas blockade of the ERK1/2 pathway inhibited H. pylori-mediated PAI-1 upregulation. These findings suggest that the upregulation of PAI-1 in H. pylori-infected gastric epithelial cells may contribute to the carcinogenic process.

The effects of cyclooxygenase2-prostaglandinE2 pathway on Helicobacter pylori-induced urokinase-type plasminogen activator system in the gastric cancer cells

BACKGROUND

Urokinase-type plasminogen activator (uPA) and its receptor (uPAR) play an important role in the destruction of the extracellular matrix and basement membrane. The induction of uPA and uPAR in the gastric cancer cells with H. pylori has been demonstrated previously. The involvement of COX-2-PGE2 pathway in the uPA system (uPA and uPAR) expression is unclear.

METHODS

Gastric cancer cells (MKN45) were co-cultured with H. pylori standard strain (NCTC11637). The specific inductions of uPA and uPAR mRNA were examined by reverse transcription-polymerase chain reaction amplification. The secreted uPA antigen was measured by ELISA. To evaluate the involvement of COX-2 and PGE2 pathway in H. pylori-induced uPA and uPAR expressions, we examined the effects of COX-2 inhibitor and PGE2 receptor antagonist on H. pylori-induced uPA and uPAR expression in the gastric cancer cells.

RESULTS

The expressions of both uPA and uPAR mRNAs in the gastric cancer cells increased obviously (12-fold and 3-fold, respectively) with H. pylori stimulation. The amount of uPA antigen into the culture medium increased dramatically with H. pylori stimulation. The COX-2 expression level in the gastric cancer cells increased remarkably with H. pylori stimulation. H. pylori-induced uPA and uPAR expression levels were suppressed with COX2 inhibitor treatment. The amount of PGE2 antigen into the culture medium increased dramatically 24 hours after H. pylori stimulation. The gastric cancer cells expressed EP2 and EP4 subtypes. EP2 receptor antagonist suppressed the H. pylori-induced uPA and uPAR expressions in the gastric cancer cells.

CONCLUSIONS

Our results indicated that COX2-PGE2 pathway may be involved in H. pylori-associated uPA and uPAR induction, and that COX-2 inhibitor or EP2 receptor antagonist may inhibit angiogenesis and tumor invasion via suppression of the uPA system.

Involvement of hypoxia-inducing factor-1alpha-dependent plasminogen activator inhibitor-1 up-regulation in Cyr61/CCN1-induced gastric cancer cell invasion

Cysteine-rich 61 (Cyr61/CCN1), one of the members of CCN family, has been implicated in the progression of human malignancies. Previously, our studies have demonstrated that Cyr61/CCN1 has a role in promoting gastric cancer cell invasion, but the mechanism is not clear yet. Here, we found that hypoxia-inducing factor-1alpha (HIF-1alpha) protein, but not mRNA, expression was significantly elevated in gastric cancer cells overexpressing Cyr61. Supportively, a profound reduction of endogenous HIF-1alpha protein was noted in one highly invasive cell line, TSGH, when transfected with antisense Cyr61. By comparison, the induction kinetics of HIF-1alpha protein by recombinant Cyr61 (rCyr61) was distinct from that of insulin-like growth factor-1 and CoCl(2) treatment, both well known for induction of HIF-1alpha. Using cycloheximide and MG132, we demonstrated that the Cyr61-mediated HIF-1alpha up-regulation was through de novo protein synthesis, rather than increased protein stability. rCyr61 could also activate the PI3K/AKT/mTOR and ERK1/2 signaling pathways, both of which were essential for HIF-1alpha protein accumulation. Blockage of HIF-1alpha activity in Cyr61-expressing cells by transfecting with a dominant negative (DN)-HIF-1alpha strongly inhibited their invasion ability, suggesting that elevation in HIF-1alpha protein is vital for Cyr61-mediated gastric cancer cell invasion. In addition, several HIF-1alpha-regulated invasiveness genes were examined, and we found that only plasminogen activator inhibitor-1 (PAI-1) showed a significant increase in mRNA and protein levels in cells overexpressing Cyr61. Treatment with PAI-1-specific antisense oligonucleotides or function-neutralizing antibodies abolished the invasion ability of the Cyr61-overexpressing cells. Transfection with dominant negative-HIF-1alpha to block HIF-1alpha activity also effectively reduced the elevated PAI-1 level. In conclusion, our data provide a detailed mechanism by which Cyr61 promoted gastric cancer cell invasive ability via an HIF-1alpha-dependent up-regulation of PAI-1.

Serum amyloid A enhances plasminogen activation: implication for a role in colon cancer

We have recently reported that the acute phase protein serum amyloid A (SAA), is locally and differentially expressed in neoplastic tissues of human colon. In the present study, we demonstrate that SAA enhances the plasminogen activation (PA)-activity of HT-29 colon cancer cell line. Cell-associated PA-activity was measured following the plasminogen-dependent ability of the cells to cleave the chromogenic substrate S-2251. The SAA-enhanced PA-activity was inhibited by anti-SAA antibodies. These antibodies also decreased the basal PA-activity of HT-29 cells and neutralized their cytokines (Interleukin-1beta+Interleukin-6)-enhanced PA-activity. Using specific chromogenic substrates and the fibrin clot-lysis assay, we found that SAA enhances also the PA-activity mediated by purified urokinase- and tissue-type plasminogen activators. Together, the data indicate that SAA enhances plasminogen activation and suggest its possible role in plasmin(ogen)-mediated colon cancer progression.

p75 Neurotrophin Receptor Inhibits Invasion and Metastasis of Gastric Cancer

The p75 neurotrophin receptor (p75NTR) is a focus for study at present. However, its function in gastric cancer was not elucidated. Here, we investigated its relation with metastasis of gastric cancer. By immunohistochemistry, we found that the positive rate of p75NTR expression in metastatic gastric cancer was 15.09% (16 of 106), which was lower compared with nonmetastatic gastric cancer (64.15%; 68 of 106). The average staining score in nonmetastatic gastric cancer was significantly higher than in metastatic gastric cancer (1.21 +/- 0.35 versus 0.23 +/- 0.18; P<0.01). p75NTR protein level was also lowly expressed in the highly liver-metastatic gastric cancer cell line XGC9811-L compared with other gastric cancer cell lines by Western blotting. It could also significantly inhibit the in vitro adhesive, invasive, and migratory and in vivo metastatic abilities of gastric cancer cell lines SGC7901 and MKN45 by reducing urokinase-type plasminogen activator (uPA) and matrix metalloproteinase (MMP)-9 proteins and by increasing tissue inhibitor of matrix metalloproteinase (TIMP)-1 protein. Further studies showed that p75NTR could suppress the nuclear factor-kappaB (NF-kappaB) signal. SN50, a specific inhibitor of NF-kappaB, which could inhibit in vitro invasive and migratory abilities of gastric cancer cells, reduced expression of uPA and MMP9 proteins and increased expression of TIMP1 protein. Taken together, p75NTR had the function of inhibiting the invasive and metastatic abilities of gastric cancer cells, which was mediated, at least partially, by down-regulation of uPA and MMP9 proteins and up-regulation of TIMP1 protein via the NF-kappaB signal transduction pathway. Our studies suggested that p75NTR may be used as a new potential therapeutic target in metastatic gastric cancer.

Helicobacter pylori and gastric cancer

PURPOSE OF REVIEW

Although chronic Helicobacter pylori infection is the strongest known risk factor for development of gastric adenocarcinoma, only a small proportion of infected individuals will ever develop tumours. This article discusses various bacterial, host and environmental factors which may influence an individual's susceptibility.

RECENT FINDINGS

Recent research on bacterial virulence factors has focussed upon the cag pathogenicity island, particularly its roles in regulating epithelial growth and adhesion. Studies of host genetic factors have included several analyses of polymorphisms in inflammatory cytokines in human cohorts. Animal studies have recently clarified the roles of dysregulated epithelial apoptosis, proliferation and differentiation pathways during gastric carcinogenesis, and novel experiments involving H. felis infection of bone marrow transplanted irradiated mice have suggested that gastric cancer may originate from bone marrow-derived stem cells. Important roles for signalling between epithelial and mesenchymal cells, particularly myofibroblasts, are also emerging. Recent research on the importance of environmental factors has demonstrated how helminth coinfection may protect against atrophic gastritis and T helper type 1 responses.

SUMMARY

Complex interactions between several bacterial, host genetic and environmental factors determine whether H. pylori infected individuals develop gastric carcinoma. The importance of bone marrow stem cell engraftment during human gastric neoplasia is an area requiring urgent investigation.