Differential expression of nitric oxide synthase in human stomach cancer

Levels of oxidative stress in patients with neoadjuvant chemotherapy for gastric cancer: correlation with treatment response

Objective

The intent of this study was to investigate the relationship between oxidative stress and treatment response in gastric cancer patients undergoing neoadjuvant chemotherapy.

Methods

Blood samples from 108 patients and 108 healthy subjects were collected, and all patients were enrolled in SOX chemotherapy. The patients received four cycles of neoadjuvant chemotherapy. Blood samples were collected to determine oxidative stress levels at baseline prior to beginning chemotherapy, and at the end of cycles 2 and 4. The patients receiving neoadjuvant chemotherapy were followed up for several months to years. A survival curve was created according to the follow-up information from the patients. In addition, the correlation between oxidative stress level and treatment effect was evaluated and ROC curves were plotted according to the final collected data.

Results

Compared with the normal group, the levels of the antioxidant index decreased while the peroxide index increased in the patients. Conversely, when patients were compared before and after chemotherapy, the antioxidant index increased but the peroxide index decreased. Furthermore, the antioxidant index increased in the response group while the peroxide index decreased in the non-response group.

Conclusion

Patients with an increased antioxidant index after chemotherapy have good treatment responsiveness. These indicators can also be used as predictors to judge the patients' response to chemotherapy.

Gasotransmitters in the tumor microenvironment: Impacts on cancer chemotherapy (Review)

Nitric oxide, carbon monoxide and hydrogen sulfide are three endogenous gasotransmitters that serve a role in regulating normal and pathological cellular activities. They can stimulate or inhibit cancer cell proliferation and invasion, as well as interfere with cancer cell responses to drug treatments. Understanding the molecular pathways governing the interactions between these gases and the tumor microenvironment can be utilized for the identification of a novel technique to disrupt cancer cell interactions and may contribute to the conception of effective and safe cancer therapy strategies. The present review discusses the effects of these gases in modulating the action of chemotherapies, as well as prospective pharmacological and therapeutic interfering approaches. A deeper knowledge of the mechanisms that underpin the cellular and pharmacological effects, as well as interactions, of each of the three gases could pave the way for therapeutic treatments and translational research.

Nitric Oxide Synthase Potentiates the Resistance of Cancer Cell Lines to Anticancer Chemotherapeutics

BACKGROUND

Despite the advancement in the fields of medical science and molecular biology, cancer is still the leading cause of death worldwide. Chemotherapy is a choice for treatment; however, the acquisition of chemo-resistance is a major impediment to cancer management. Many mechanisms have been postulated regarding the acquisition of chemo-resistance in breast cancer the impact on cellular signaling and the induction of apoptosis in tumour cells. The mechanism of the apoptotic mutation of p53 and bcl-2 proteins is commonly associated with increased resistance to apoptosis and, therein, to chemotherapy.

OBJECTIVES

The current study was aimed to investigate A172 and MDA-MB-231 cancer cells' sensitivity against chemotherapeutic drugs, including cisplatin, doxorubicin, and paclitaxel with different doses. Moreover, it estimates the resistance of cancer cells by evaluating nitric oxide synthase (NOS) expression and evaluate its correlation with the expression profile proteins of the apoptosis regulating Bcl-2 family.

METHODS

Dose-dependent sensitivity to cisplatin, doxorubicin, or paclitaxel was evaluated on spheroid cultured A172 and MDA-MB-231 cells lines as measured by time-lapse microscopy over a 72h period. Expressions of two nitric oxides (NO) synthases isoforms (iNOS, eNOS), anti-apoptotic (Bcl-2, phospho-Bcl-2, Mcl-1, and Bcl-xL), and pro-apoptotic (BID, Bim, Bok, Bad, Puma, and Bax) were evaluated by Western blot. The effect of NO modulation on anti- and pro-apoptotic molecule expression was also studied using Western blot.

RESULT

A172 cells show more resistance to chemotherapy drugs than MDA-MB-231 cancer cells. Therefore, they need higher doses for apoptosis. Resistance of gliomas might be returned to the higher significant expression of endothelial eNOS expression. It was clear that there is not a significant effect of NO modulation on the expression of pro-and anti-apoptotic proteins on both cell lines.

CONCLUSION

The present work provides a putative mechanism for the acquisition of drug resistance in breast cancer and glioma, which might be significant for clinical outcomes.

Current Advances of Nitric Oxide in Cancer and Anticancer Therapeutics

Nitric oxide (NO) is a short-lived, ubiquitous signaling molecule that affects numerous critical functions in the body. There are markedly conflicting findings in the literature regarding the bimodal effects of NO in carcinogenesis and tumor progression, which has important consequences for treatment. Several preclinical and clinical studies have suggested that both pro- and antitumorigenic effects of NO depend on multiple aspects, including, but not limited to, tissue of generation, the level of production, the oxidative/reductive (redox) environment in which this radical is generated, the presence or absence of NO transduction elements, and the tumor microenvironment. Generally, there are four major categories of NO-based anticancer therapies: NO donors, phosphodiesterase inhibitors (PDE-i), soluble guanylyl cyclase (sGC) activators, and immunomodulators. Of these, NO donors are well studied, well characterized, and also the most promising. In this study, we review the current knowledge in this area, with an emphasis placed on the role of NO as an anticancer therapy and dysregulated molecular interactions during the evolution of cancer, highlighting the strategies that may aid in the targeting of cancer.

Clinical significance of the long noncoding RNA RP11-19P22.6-001 in gastric cancer

BACKGROUND

Long non-coding RNAs (lncRNAs) play roles in carcinogenesis; however, the significance of most lncRNAs in gastric cancer is unclear.

OBJECTIVE

To explore the diagnostic value of the long noncoding RNA RP11-19P22.6-001 in gastric cancer.

METHODS

RP11-19P22.6-001 levels in gastric cancer tissues and paired non-tumor tissues were analyzed by quantitative reverse transcription-polymerase chain reaction. Since RP11-19P22.6-001 acts in cis to regulate nitric oxide synthase 2 (NOS2), we also analyzed NOS2 expression and its correlation with gastric cancer. Finally, to analyze the potential diagnostic values of RP11-19P22.6-001, a receiver operating characteristic (ROC) curve was constructed.

RESULTS

RP11-19P22.6-001 expression was significantly downregulated in 70.91% (78/110) of gastric cancer tissues compared to that of adjacent normal tissues. However, NOS2 was upregulated in 75.45% (83/110) of gastric cancer tissues. RP11-19P22.6-001 expression levels were associated with invasion, lymph node metastasis, and TNM stage. The areas under the ROC curves (AUC) were 0.662 and 0.671 for RP11-19P22.6-001 and NOS2, respectively. More importantly, the combined use of these parameters increased the AUC to 0.704.

CONCLUSIONS

RP11-19P22.6-001 and NOS2 may be new biomarkers for the diagnosis and prognosis of gastric cancer. The combined use of lncRNAs and their target genes may be a promising method to increase the diagnostic value of lncRNAs in cancer.

A multi-targeted approach to suppress tumor-promoting inflammation

Cancers harbor significant genetic heterogeneity and patterns of relapse following many therapies are due to evolved resistance to treatment. While efforts have been made to combine targeted therapies, significant levels of toxicity have stymied efforts to effectively treat cancer with multi-drug combinations using currently approved therapeutics. We discuss the relationship between tumor-promoting inflammation and cancer as part of a larger effort to develop a broad-spectrum therapeutic approach aimed at a wide range of targets to address this heterogeneity. Specifically, macrophage migration inhibitory factor, cyclooxygenase-2, transcription factor nuclear factor-κB, tumor necrosis factor alpha, inducible nitric oxide synthase, protein kinase B, and CXC chemokines are reviewed as important antiinflammatory targets while curcumin, resveratrol, epigallocatechin gallate, genistein, lycopene, and anthocyanins are reviewed as low-cost, low toxicity means by which these targets might all be reached simultaneously. Future translational work will need to assess the resulting synergies of rationally designed antiinflammatory mixtures (employing low-toxicity constituents), and then combine this with similar approaches targeting the most important pathways across the range of cancer hallmark phenotypes.

Association of endothelial nitric oxide synthase gene T-786C promoter polymorphism with gastric cancer

AIM: To investigate the role of endothelial nitric oxide synthase -786T > C promoter polymorphism in the etiology of gastric cancer (GC).

METHODS: A total of 150 GC patients and 150 control subjects were included in the study. The information on demographic features was elicited with an informed consent from all the patients and control subjects using a structured questionnaire. Helicobacter pylori (H. pylori) infectivity status was tested in antral biopsies from all the subjects by rapid urease test following the method of Vaira et al. Genomic DNA was isolated from whole blood samples following the salting out method of Lahiri et al. Genotype analysis of the rs2070744 polymorphism was carried out by allele-specific polymerase chain reaction method. The genotypes were determined based on the appearance of bands on an agarose gel stained with ethidium bromide under ultraviolet gel documentation with the help of 100 bp ladder. Odds ratios and corresponding 95%CIs were determined using java stat online software.

RESULTS: There was a significant difference in the distribution of C allele (C vs T; P = 0.000, OR = 5.038) in patient group compared to the control subjects exhibiting a fivefold increased risk for GC. When the T/T and C/C genotypes were compared, there was an enhanced GC risk for individuals with C/C genotype (T/T vs C/C; P = 0.000). Among the demographic factors, smoking and alcoholism were the common risk factors in patients compared to the control subjects (P < 0.05). Patients with smoking and alcoholism developed cancer even in heterozygous T/C condition (smoking: P = 0.020 and alcoholism: P = 0.005). Individuals with H. pylori infection showed seven fold increased risk for cancer. All the patients with C/C genotype revealed a significant association between H. pylori infection and GC. Among the patients 2.4% of them revealed familial incidence of GC. No significant difference was noticed between cases and controls with regard to consanguinity (P = 0.473).

CONCLUSION: The Present data suggest that eNOS-786 C/C genotype and C allele may be considered as potential risk factors in patients with GC.

Inducible nitric oxide synthase expression in gastric adenocarcinoma: impact on lymphangiogenesis and lymphatic metastasis

Background

Lymphatic metastasis is the most important parameter in the spread of gastric carcinomas. Nitric oxide (NO) is a signaling molecule that plays an important role in inflammation and carcinogenesis. In this study, the possible link between inducible nitric oxide synthase (iNOS) expression with lymphangiogenesis and the clinicopathological parameters of gastric carcinomas was investigated.

Methods

In this study, iNOS expression and D2-40 (lymphatic endothelium-specific marker monoclonal antibody) reactivity were examined immunohistochemically in 41 gastric adenocarcinoma and 20 non-neoplastic gastric tissues. iNOS expression was scored semiquantitatively in the tumor parenchyma and stroma. D2-40-positive lymphatic vessels were used in the determination of lymphatic invasion and intratumoral and peritumoral lymphatic vascular density.

Results

iNOS expression was higher in gastric carcinoma tissue compared with non-neoplastic tissue. Particularly, iNOS expression in tumor cells was found to be closely related to lymphangiogenesis and lymphatic metastasis. The density of lymphatic invasion as well as intratumoral and peritumoral lymphatic vascular density were positively correlated with lymph node metastasis.

Conclusions

Our results suggest that iNOS-mediated NO formation plays an important role in gastric carcinogenesis, tumor lymphangiogenesis, and the development of lymphatic metastases. Inhibition of the NO pathway may be an alternative treatment of gastric carcinomas.

Virtual slides

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1713572940104388.

Macrophage-tumor cell interactions regulate the function of nitric oxide

Tumor cell-macrophage interactions change as the tumor progresses, and the generation of nitric oxide (NO) by the inducible nitric oxide synthase (iNOS) plays a major role in this interplay. In early stages, macrophages employ their killing mechanisms, particularly the generation of high concentrations of NO and its derivative reactive nitrogen species (RNS) to initiate tumor cell apoptosis and destroy emerging transformed cells. If the tumor escapes the immune system and grows, macrophages that infiltrate it are reprogramed in situ by the tumor microenvironment. Low oxygen tensions (hypoxia) and immunosuppressive cytokines inhibit iNOS activity and lead to production of low amounts of NO/RNS, which are pro-angiogenic and support tumor growth and metastasis by inducing growth factors (e.g., VEGF) and matrix metalloproteinases (MMPs). We review here the different roles of NO/RNS in tumor progression and inhibition, and the mechanisms that regulate iNOS expression and NO production, highlighting the role of different subtypes of macrophages and the microenvironment. We finally claim that some tumor cells may become resistant to macrophage-induced death by increasing their expression of microRNA-146a (miR-146a), which leads to inhibition of iNOS translation. This implies that some cooperation between tumor cells and macrophages is required to induce tumor cell death, and that tumor cells may control their fate. Thus, in order to induce susceptibility of tumors cells to macrophage-induced death, we suggest a new therapeutic approach that couples manipulation of miR-146a levels in tumors with macrophage therapy, which relies on ex vivo stimulation of macrophages and their re-introduction to tumors.

Inducible nitric oxide synthetase genotype and Helicobacter pylori infection affect gastric cancer risk

AIM

To investigate the association of the inducible nitric oxide synthetase (iNOS) C150T polymorphism with Helicobacter pylori (H. pylori) infection and gastric cancer (GC) risk in Iran.

METHODS

In order to determine whether there was a correlation between iNOS genotype and GC in Iran, we conducted a case-control study using samples from 329 individuals. For each sample, the C150T iNOS polymorphism was genotyped by polymerase chain reaction (PCR) and restriction digestion. Patients were grouped by cancer presence, demographic and behavior characteristics, and H. pylori infection status. Statistical tests were conducted to determine whether any behavioral factors or a particular iNOS genotype was associated with GC in the study population.

RESULTS

In this population, we found that smoking, hot beverage consumption, a familial history of GC and H. pylori infection status were significantly associated with GC development (P = 0.015, P < 0.001, P = 0.0034, and P < 0.015, respectively). The distribution of the C150T iNOS genotypes among the two study groups was not statistically significant alone, but was impacted by H. pylori infection status. When compared to the non-H. pylori infected group, cancer patients who had a heterozygous CT genotype and were also infected with H. pylori were 2.1 times more at risk of developing GC [odds ratio (OR) = 2.1, P = 0.03] while those with a homozygous TT genotype and infected with H. pylori were 5.0 times more at risk of developing GC (OR = 5.0, P = 0.029). In contrast, this association was not seen in patients in the control group.

CONCLUSION

A CT or TT polymorphism at position 150 in the iNOS gene significantly increases the risk of GC and may be a marker for GC susceptibility.

Oxidative stress in non-small cell lung cancer patients after chemotherapy: association with treatment response

Levels of lipid peroxidation, nitric oxide and glutathione, as well as superoxide dismutase activity were evaluated in non-small cell lung cancer patients before and after chemotherapy. Oxidative stress was shown to influence treatment efficacy and survival of these patients.

BACKGROUND AND OBJECTIVE

The aim of this study was to assess the level of oxidative stress after chemotherapy in non-small cell lung cancer patients, and its association with treatment response and survival.

METHODS

Two hundred and three previously untreated non-small cell lung cancer patients and 150 healthy subjects were selected for the study. Patients received cisplatin+etoposide, and were followed for up to six cycles, for evaluation of oxidative stress. Blood levels of lipid peroxidation products (LPO), glutathione (GSH) and nitric oxide (NO), and superoxide dismutase (SOD) activity were measured at day 0 and after the third and sixth cycles of chemotherapy. Response and survival were measured at the end of follow up. Survival was estimated by the Kaplan-Meier method using the log-rank test.

RESULTS

In the patients, pretreatment levels of LPO and NO were low, while GSH and SOD levels were high compared with those after the third and sixth cycles of chemotherapy. Among the 203 patients, there were 51 deaths, 82 non-responders and 70 responders at the end of the sixth cycle. Overall mean survival was higher among responders than non-responders (24.6 vs 21.2 weeks, P<0.01). The hazard ratio was 2.4 (95% CI: 1.3-3.77). Pretreatment levels of oxidative stress were similar among responders and non-responders (P>0.05). After the third and sixth cycles of chemotherapy, LPO and NO levels were low (P<0.05 or P<0.01) and GSH levels and SOD activity were high (P<0.05 or P<0.01) in responders as compared with non-responders.

CONCLUSIONS

In lung cancer patients, oxidative stress increased and anti-oxidant enzymes decreased as the disease progressed. Chemotherapy may suppress oxidative stress and decreased anti-oxidant enzyme activity in responders as compared with non-responders. These effects may contribute to improved survival among responders.

(+)-Catechin inhibits tumour angiogenesis and regulates the production of nitric oxide and TNF-α in LPS-stimulated macrophages

The anti-angiogenic activity of (+)-catechin as well as its regulatory effect on the production of nitric oxide and TNFα were studied using in vivo and in vitro models. In vivo angiogenic activity was studied using B16F-10 melanoma cell-induced capillary formation in C57BL/6 mice. Administration of (+)-catechin significantly inhibited (36.09%) the number of tumour-directed capillaries induced by injecting B16F-10 melanoma cells on the ventral side of C57BL/6 mice. The cytokine profile in the serum of these animals showed a drastically increased level of proinflammatory cytokines such as IL-1β, IL-6, TNF-α, GM-CSF and the direct endothelial cell proliferating agent, VEGF. Administration of (+)-catechin could differentially regulate elevation of these cytokines. The differential elevation is further evidenced by the increased production of IL-2 and tissue inhibitor of metalloproteinase-1 (TIMP-1) in the B16F-10 injected, (+)-catechin-treated animals. In vitro L929 bioassay revealed the inhibition of TNF-α production by (+)-catechin treatment. In the rat aortic ring assay, (+)-catechin inhibited the microvessel outgrowth at non-toxic concentrations. (+)-Catechin at non-toxic concentrations (5—25 µg/ml) showed significant inhibition in the proliferation, migration and tube formation of endothelial cells, which are the key events in the process of angiogenesis. (+)-Catechin also showed inhibitory effect on VEGF mRNA levels in B16F-10 melanoma cells. (+)-Catechin inhibited the production of NO and TNF-α in LPS-stimulated primary macrophages. Taken together, these results demonstrate that (+)-catechin inhibits tumour-specific angiogenesis by regulating the production of pro- and anti-angiogenic factors such as pro-inflammatory cytokines, nitric oxide, VEGF, IL-2 and TIMP-1. These results also suggest that (+)-catechin could significantly inhibit nitrite and TNF-α production in LPS-stimulated macrophages.

Aberrant regulation of argininosuccinate synthetase by TNF-alpha in human epithelial ovarian cancer

The pro-inflammatory cytokine, tumour necrosis factor-alpha, TNF-alpha, is dysregulated in malignant compared with normal ovarian surface epithelium (OSE). Several epidemiological studies have associated inflammation with ovarian tumorigenesis, with TNF-alpha playing a key role in modulating invasion, angiogenesis and metastasis. Here, we show that TNF-alpha also induces expression of arate-limiting enzyme in arginine synthesis, argininosuccinate synthetase (AS), thereby linking inflammation with several arginine-dependent metabolic pathways, implicated in accelerated carcinogenesis and tumour progression. Having identified AS mRNA induction in TNF-alpha-treated IGROV-1 ovarian cancer cells, using RNA-arbitrarily primed-PCR, we then observed differential regulation of AS mRNA and protein in malignant, compared with normal, OSE cells. A cDNA cancer profiling array with matched normal ovarian and ovarian tumour samples revealed increased expression of AS mRNA in the latter. Moreover, AS protein co-localised with TNF-alpha in ovarian cancer cells, with significantly higher levels of AS in malignant compared with normal ovarian tissue. Increased co-expression of AS and TNF-alpha mRNA was also observed in 2 other epithelial tumours, non-small cell lung and stomach cancer, compared with normal corresponding tissues. In summary, high levels of AS expression, which may be required for several arginine-dependent processes in cancer, including the production of nitric oxide, proline, pyrimidines and polyamines, is regulated by TNF-alpha and may provide an important molecular pathway linking inflammation and metabolism to ovarian tumorigenesis.

Allyl isothiocyanate (AITC) and phenyl isothiocyanate (PITC) inhibit tumour-specific angiogenesis by downregulating nitric oxide (NO) and tumour necrosis factor-alpha (TNF-alpha) production

Angiogenesis, a crucial step in the growth and metastasis of cancers, is initiated with vasodilation mediated by nitric oxide (NO). The pro-inflammatory cytokine, tumour necrosis factor-alpha (TNF-alpha), is a mediator of nitric oxide synthesis. We analyzed the effect of allyl isothiocyanate (AITC) and phenyl isothiocyanate (PITC) on serum NO as well as TNF-alpha level during angiogenesis. In vivo antiangiogenic activity was studied using B16F-10 melanoma cell-induced capillary formation in C57BL/6 mice. Intraperitoneal administration of AITC and PITC at a concentration of 25 microg/dose/animal significantly inhibited tumour-directed capillary formation. Treatment of AITC and PITC significantly downregulated serum NO as well as TNF-alpha level in angiogenesis-induced animals compared to untreated control animals. The in vitro antiangiogenic study, using rat aortic ring assay, showed that both AITC and PITC at non-toxic concentrations inhibited the production of proangiogenic factors from B16F-10 melanoma cells which was evident with the inhibition of microvessel outgrowth from aortic rings. Both AITC and PITC significantly inhibited sodium nitroprusside as well as TNF-alpha-induced microvessel outgrowth from rat aortic ring. Administration of AITC and PITC also significantly reduced NO and TNF-alpha production by LPS-stimulated macrophages both in vivo as well as in vitro. Bio-assay using serum of angiogenesis-induced animals and supernatant from LPS-stimulated macrophages clearly confirmed the downregulatory action of AITC and PITC on TNF-alpha production. These results clearly demonstrated that AITC and PITC inhibited tumour-specific angiogenesis by downregulating NO and TNF-alpha production.

Differential expression of apoptosis related proteins and nitric oxide synthases in Epstein Barr associated gastric carcinomas

AIM: To determine the incidence of Epstein Barr virus associated gastric carcinoma (GC) in Brazil and compare the expressions of apoptosis related proteins and nitric oxide synthases between EBV positive and negative gastric carcinoma.

METHODS: In situ hybridization of EBV-encoded small RNA-1 (EBER-1) and PCR was performed to identify the presence of EBV in GCs. Immunohistochemistry was used to identify expressions of bcl-2, bcl-xl, bak, bax, p53, NOS-1, NOS-2, and NOS-3 proteins in 25 EBV positive GCs and in 103 EBV negative GCS.

RESULTS: 12% of the cases of GC (25/208) showed EBER-1 and EBNA-1 expression. The cases were preferentially of diffuse type with intense lymphoid infiltrate in the stroma. EBV associated GCs showed higher expression of bcl-2 protein and lower expression of bak protein than in EBV negative GCs. Indeed, expressions of NOS-1 and NOS-3 were frequently observed in EBV associated GCs.

CONCLUSION: Our data suggest that EBV infection may protect tumor cells from apoptosis, giving them the capacity for permanent cell cycling and proliferation. In addition, EBV positive GCs show high expression of constitutive NOS that could influence tumor progression and aggressiveness.

Nitric oxide levels in serum of patients with symptomatic irreversible pulpitis

Nitric oxide (NO) affects both pain and inflammation in human tissues. Pharmacotherapy that decreases NO concentrations may have utility in treating inflammatory painful conditions. To determine the types of disorders in which such an approach should be studied, changes in NO serum levels before and after the painful inflammatory condition resolves would be helpful. This study compared the pre-treatment and post-treatment serum nitric oxide (NO) concentrations in irreversible pulpitis (inflammatory toothache). Thirty-two patients (16 males, 16 females) with irreversible pulpitis were included in this study. Before treatment, patients had severe symptoms of inflammation, but at the end of treatment no symptoms of inflammation were observed. NO concentrations were measured in serum of patients with irreversible pulpitis, before and after treatment. Differences in serum NO concentrations were not statistically significantly different before and after treatment.

Differences in oxidative stress dependence between gastric adenocarcinoma subtypes

AIM: To investigate the extent of oxidative stress in pre-neoplastic and neoplastic gastric mucosa in relation to their pathological criteria and histological subtypes.

METHODS: A total of 104 gastric adenocarcinomas from 98 patients (88 infiltrative and 16 intraepithelial tumors) were assessed immunohistochemically for expression of iNOS and occurrence of nitrotyrosine (NTYR)-containing proteins and 8-hydroxy-2’-deoxyguanosine (8-OH-dG)-containing DNA, as markers of NO production and damages to protein and DNA.

RESULTS: Tumor cells staining for iNOS, NTYR and 8-OH-dG were detected in 41%, 62% and 50% of infiltrative carcinoma, respectively. The three markers were shown for the first time in intraepithelial carcinoma. The expression of iNOS was significantly more frequent in tubular carcinoma (TC) compared to diffuse carcinoma (DC) (54% vs 18%; P = 0.008) or in polymorphous carcinoma (PolyC) (54% vs 21%; P = 0.04). NTYR staining was obviously more often found in TC than that in PolyC (72% vs 30%; P=0.03). There was a tendency towards a higher rate of iNOS staining when distant metastasis (pM) was present. In infiltrative TC, the presence of oxidative stress markers was not significantly correlated with histological grade, density of inflammation, the depth of infiltration (pT), lymph nodes dissemination (pN) and pathological stages (pTNM).

CONCLUSION: The iNOS-oxidative pathway may play an important role in TC, but moderately in PolyC and DC. DNA oxidation and protein nitration occur in the three subtypes. Based on the significant differences of NTYR levels, TC and PolyC appear as two distinct subtypes.

Streptococcus anginosus infection in oral cancer and its infection route

OBJECTIVE

To elucidate a possible involvement of Streptococcus anginosus in oral cancer, we assessed the frequency of S. anginosus infection in oral cancer tissues, and investigated its infection route.

MATERIALS AND METHOD

The tissue specimens were obtained from 46 oral cancer and three precancerous leukoplakia subjects. Frequency of S. anginosus infection was assessed by a species-specific polymerase chain reaction (PCR) assay. The genotype of the clinical isolates taken from cancer tissue and dental plaque samples was analyzed using pulsed-field gel electrophoresis (PFGE).

RESULTS

S. anginosus DNA was frequently detected in squamous cell carcinoma (19/42), but not in other types of cancer (lymphoma and rhabdomyosarcoma) or leukoplakia samples. A subject-based analysis revealed that S. anginosus was solely detected in dental plaque and not in saliva from all 19 S. anginosus-positive squamous cell carcinoma cases. Further, the genotype of S. anginosus isolated from cancer tissue was identical to that from dental plaque of the same patients.

CONCLUSION

Infection of S. anginosus could occur frequently in oral squamous cell carcinoma and that dental plaque could be a dominant reservoir of the S. anginosus.

Expression of inducible nitric oxide synthase is significantly correlated with expression of vascular endothelial growth factor and dendritic cell infiltration in patients with advanced gastric carcinoma

OBJECTIVE

Nitric oxide (NO) is a product of L-arginine to L-citrulline conversion by nitric oxide synthase (NOS). The inducible form of NOS (iNOS) is one of three classes of NOS and the strongest producer of NO. It has been reported that NO correlates with angiogenesis and immune responses in some types of cancer, however, the correlations between iNOS expression, angiogenesis, and immune responses are still unclear in gastric carcinoma.

METHODS

iNOS expression was determined in 135 gastric cancer patients by immunohistochemical procedures and compared with the expression of vascular endothelial growth factor (VEGF), microvessel (MV) density, and dendritic cell (DC) infiltration to evaluate the effect of iNOS on angiogenesis and immune responses in gastric carcinoma.

RESULTS

iNOS expression was detected in 106 (78.5%) of 135 cases. There was a close correlation between iNOS expression and VEGF expression, a correlation with MV density and an inverse correlation with DC infiltration. There was no correlation between iNOS and p53 expression. The prognoses of patients whose tumors expressed iNOS were significantly worse than those of patients whose tumors did not express iNOS. Multivariate analysis indicated iNOS expression was an independent prognostic factor.

CONCLUSION

iNOS might be associated with tumor progression by stimulating angiogenesis and suppressing immune responses in gastric carcinoma.

Anti-cancer effect of iNOS inhibitor and its correlation with angiogenesis in gastric cancer

AIM: To observe the anti-cancer effect of iNOS selective inhibitor (aminoguanidine, AG) and investigate the relationship between iNOS inhibitor and angiogenesis, infiltration or metastasis in MFC gastric cancer xenografts.

METHODS: Fifty athymic mice xenograft models were established by inoculating gastric cancer cell MFC subcutaneously. Twenty-four hours later, 0.9% sodium chloride solution, mitomycin, low dosage AG, high dosage AG, mitomycin and AG were administered by intraperitoneal injection respectively. Thus these mice were divided into five groups of 10 each randomly: control group, MMC group, AG_L group, AG_H group, MMC+AG_H group. Two weeks later the mice were killed, and the tumor weight, inhibitory rate were evaluated. Greiss assay was used to detect the nitric oxide levels in plasma. HE and immunohistochemistry staining were used to examine microvessel density (MVD) and the expression of iNOS, VEGF, and PCNA. Apoptosis was detected by using TUNEL assay.

RESULTS: The inhibitory rates in MMC+AG_H group and AG_H group were 52.9% and 47.1% respectively, which is significant statistically compared with that of control group (0). In treatment groups, the cell proliferation index (PI) was lower and apoptosis index was higher than those of control group. Microvessel density, iNOS, and VEGF in MMC+ AG_H group were 8.8 ± 2.6, 2.4 ± 1.1, and 2.1 ± 1.4 respectively, which is significant statistically compared with those of control group (68.3 ± 10.6, 11.3 ± 1.3, and 10.3 ± 1.6). The NO level in plasma of MMC+ AG_H and AG_H group were 12.7 ± 2.1 and 12.9 ± 2.0 μmol/L. Compared with that of control group (46.6 ± 2.3 μmol/L), the difference is statistically significant.

CONCLUSION: AG has anticancer effect on gastric cancer, and it has positive synergistic effect with chemotherapeutic drugs. It may play important inhibitory roles in angiogenesis of gastric cancer. The anticancer effect of iNOS inhibitors may include inducing cell apoptosis, suppressing cell proliferation and reducing angiogenesis.

Inducible nitric oxide synthase, nitrotyrosine and apoptosis in gastric adenocarcinomas and their correlation with a poor survival

AIM: To detect the presence of inducible nitric oxide synthase (iNOS), nitrotyrosine (NT) and apoptosis in gastric adenocarcinomas and their possible correlations with the clinicopathological characteristics and prognosis of gastric adenocarcinoma.

METHODS: Sixty-six specimens of gastric adenocarcinoma and corresponding adjacent normal gastric tissues were studied. Immunohistochemistry was employed to localize iNOS and NT protein and an immunohistochemical scoring system was used. The occurrence of apoptotic cell death (apoptotic index [AI]) was analyzed by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick-end labeling (TUNEL) method.

RESULTS: Results showed that iNOS expression was detected at an intermediate or high level in 41 of 66 (62%) specimens of gastric adenocarcinoma. NT expression was 58%. Neither of them was found in the normal gastric tissues; there were significant positive correlations among iNOS expression, NT expression and AI. Many clinicopathologic characteristics of gastric adenocarcinoma, such as tumor size, depth of invasion, lymph node metastasis and TNM staging, were related to iNOS and NT expressions (P<0.05). In 66 surviving patients, the 5-year survival rate of 41 patients who had tumors with intermediate or high iNOS expressions and high AIs (4.09%; 19.96%) was significantly lower than that of 25 patients who had tumors with negative or low iNOS expressions and low AIs (0.79%; 47.14%) (P = 0.001). COX’s multivariate analysis revealed that the iNOS expression was identified as one of the significant independent prognostic factors predictive of a poor survival (relative risk [RR] = 2.69).

CONCLUSION: NO produced by iNOS may play a stronger role in promoting gastric adenocarcinoma growth than in suppressing its growth. iNOS and NT expressions by gastric adenocarcinoma may correlate with a poor survival.

Expression of nitric oxide synthase in human gastric carcinoma and its relation to p53, PCNA

AIM: To investigate the expression of NOS in gastric carcinoma, and to explore the relationship between the expression of nitric oxide synthases (NOS) and p53, PCNA, pathological features and clinical staging of gastric cancer.

METHODS: The activity of NOS protein was investigated in 85 samples of human gastric carcinoma and 25 samples of normal gastric mucosal tissue by biochemical assay. We then examined the expression of NOS, p53, PCNA in 85 samples of human gastric cancer was examined by immunohistochemistry, and NOS mRNA expression in 85 gastric cancer tissue specimens by in situ hybridization.

RESULTS: Biochemical assay showed that the activity of NOS was significantly higher in gastric carcinoma than in normal gastric mucosal tissues (t = 0.4161, P<0.01). Immunohistochemistry revealed that endothelial nitric oxide synthase (eNOS) expressed in all samples of normal gastric mucosa, but only 6 cases of 85 gastric cancer specimens showed weak positive immunohistochemical reactions to eNOS (20%). Inducible nitric oxide synthase (iNOS) was expressed strongly in human gastric carcinoma (81.2%). In situ hybridization analysis showed that iNOS mRNA expression was significantly stronger than eNOS mRNA expression in gastric cancer tissue (χ² = 10.23, P<0.01). The expression of iNOS in gastric cancer was associated with differentiation, clinical stages or lymph node metastases (r = 0.3426, P<0.05). However, iNOS expression did not correlate with histological classifications and morphological types. The expression of iNOS was significantly correlated with p53 or PCNA expression (r = 0.3612, P<0.05). The expression of neuronal nitric oxide synthase (nNOS) was not examined by immunohistochemistry and in situ hybridization in gastric cancer specimens and normal gastric mucosa.

CONCLUSION: In human gastric cancer, there is an enhanced expression of iNOS, but not of eNOS. NOS promotes the proliferation of tumor cells and plays an important role in gastric cancer spread. Inactivation of antioncogene p53 and overexpression of iNOS might play a synergetic role in the process of carcinogenesis of human gastric carcinoma.

Increased oxidative DNA damage, inducible nitric oxide synthase, nuclear factor κB expression and enhanced antiapoptosis-related proteins in Helicobacter pylori-infected non-cardiac gastric adenocarcinoma

AIM: Several epidemiological studies have demonstrated a close association between Helicobacter pylori (H Pylori) infection and non-cardiac carcinoma of the stomach. H pylori infection induces active inflammation with neutrophilic infiltrations as well as production of oxygen free radicals that can cause DNA damage. The DNA damage induced by oxygen free radicals could have very harmful consequences, leading to gene modifications that are potentially mutagenic and/or carcinogenic. The aims of the present study were to assess the effect of H pylori infection on the expression of inducible nitric oxidative synthase (iNOS) and the production of 8 -hydroxy-deoxyguanosine (8-OHdG), a sensitive marker of oxidative DNA injury in human gastric mucosa with and without tumor lesions, and to assess the possible factors affecting cell death signaling due to oxidative DNA damage.

METHODS: In this study, 40 gastric carcinoma specimens and adjacent specimens were obtained from surgical resection. We determined the level of 8-OHdG formation by HPLC-ECD, and the expression of iNOS and mechanism of cell death signaling [including nuclear factor-κB(NFκB), MEKK-1, Caspase 3, B Cell lymphomal leukemia-2 (Bcl-2), inhibitor of apoptosis protein (IAP ) and myeloid cell leukemia-1 (Mcl-1)] by Western-blot assay.

RESULTS: The concentrations of 8-OHdG, iNOS, NFκB, Mcl-1 and IAP were significantly higher in cancer tissues than in adjacent non-cancer tissues. In addition, significantly higher concentrations of 8-OHdG, iNOS, NFκB, Mcl-1 and IAP were detected in patients infected with H pylori compared with patients who were not infected with H pylori. Furthermore, 8-OHdG, iNOS, NFκB, Mcl-1 and IAP concentrations were significantly higher in stage 3 and 4 patients than in stage 1 and 2 patients.

CONCLUSION: Chronic H pylori infection induces iNOS expression and subsequent DNA damage as well as enhances anti-apoptosis signal transduction. This sequence of events supports the hypothesis that oxygen-free radical-mediated damage due to H pylori plays a pivotal role in the development of gastric carcinoma in patients with chronic gastritis.

Depletion of deoxyribonucleoside triphosphate pools in tumor cells by nitric oxide

Nitric oxide displays pro- and anti-tumor activities, prompting further studies to better understand its precise role. Nitric oxide inhibits ribonucleotide reductase (RnR), the limiting enzyme for de novo dNTP synthesis. We report here the first detailed analysis of dNTP variations induced in tumor cells by NO. NO prodrugs induced a depletion in dNTP pools and an activation of the pyrimidine salvage pathway, as did hydroxyurea, the prototypic RnR inhibitor. In the presence of dipyridamole, which blocked salvaged dNTP synthesis, depletion of dNTP pools was also observed in tumor cells cocultured with macrophages expressing the high-output iNOS activity. This effect was rapid, reversible, blocked by NO scavengers, and cGMP independent. It was quantitatively correlated to iNOS activity. In the absence of dipyridamole, NO still induced a decrease in dATP concentration in tumor cells cocultured with macrophages, whereas surprisingly, concentrations of dCTP and dTTP expanded considerably, resulting in a strong imbalance in dNTP pools. NO prodrugs did not cause such an increase in pyrimidine dNTP, suggesting that pyrimidine nucleosides were released by NO-injured macrophages. Altered dNTP levels have been reported to promote mutagenesis and apoptosis. It is suggested that abnormal changes in dNTP pools in tumors might contribute to NO-dependent toxicity.

Postanoxic functional recovery of the developing heart is slightly altered by endogenous or exogenous nitric oxide

Nitric oxide synthase (NOS) is strongly and transiently expressed in the developing heart but its function is not well documented. This work examined the role, either protective or detrimental, that endogenous and exogenous NO could play in the functioning of the embryonic heart submitted to hypoxia and reoxygenation. Spontaneously beating hearts isolated from 4-day-old chick embryos were either homogenized to determine basal inducible NOS (iNOS) expression and activity or submitted to 30 min anoxia followed by 100 min reoxygenation. The chrono-, dromo- and inotropic responses to anoxia/reoxygenation were determined in the presence of NOS substrate (L-arginine 10 mM), NOS inhibitor L-NIO (1-5 mM), or NO donor (DETA NONOate 10-100 microM). Myocardial iNOS was detectable by immunoblotting and its activity was specifically decreased by 53% in the presence of 5 mM L-NIO. L-Arginine, L-NIO and DETA NONOate at 10 microM had no significant effect on the investigated functional parameters during anoxia/reoxygenation. However, irrespective of anoxia/reoxygenation, DETA NONOate at 100 microM decreased ventricular shortening velocity by about 70%, and reduced atrio-ventricular propagation by 23%. None of the used drugs affected atrial activity and hearts of all experimental groups fully recovered at the end of reoxygenation. These findings indicate that (1) by contrast with adult heart, endogenously released NO plays a minor role in the early response of the embryonic heart to reoxygenation, (2) exogenous NO has to be provided at high concentration to delay postanoxic functional recovery, and (3) sinoatrial pacemaker cells are the less responsive to NO.

Diffuse and intestinal type gastric carcinomas differ in their expression of apoptosis related proteins

BACKGROUND

Gastric carcinomas can be divided into intestinal and diffuse types, with the last type having a worse prognosis.

AIMS

To investigate whether specific patterns in the expression of apoptosis related proteins correlate with carcinoma type and/or prognosis

METHODS

The expression of Fas, Bcl-2, Bax, Bcl-xl, cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) was studied immunohistochemically and the extent of apoptosis and proliferation was investigated in 11 cases of intestinal type and in eight cases of diffuse type carcinoma.

RESULTS

Fas was expressed in all intestinal type and in one diffuse type carcinoma. Bcl-xl was expressed in 10 of 11 intestinal type and in one of eight diffuse type carcinomas. Bcl-2 was expressed in lamina propria immune cells. iNOS was expressed in six of 11 intestinal type and in four of eight diffuse type carcinomas, and COX-2 was expressed in eight of 11 intestinal type and in six of eight diffuse type carcinomas.

CONCLUSION

Fas and Bcl-xl expression can differentiate between intestinal type and diffuse type gastric carcinomas. No differences in apoptosis and proliferation between intestinal type and diffuse type gastric carcinomas were observed.

Expression of inducible nitric oxide synthase in thyroid neoplasms: immunohistochemical and molecular analysis

To understand the role of inducible nitric oxide synthase (iNOS) in thyroid tumorigenesis, immunohistochemical staining of 36 surgical specimens of thyroid neoplasm that consisted of seven follicular adenomas, 12 papillary carcinomas, seven follicular carcinomas, five medullary carcinomas, and five anaplastic carcinomas were analyzed. In addition, 20 specimens of normal thyroid were used as control samples. Reverse transcription-polymerase chain reaction and western blot analysis were also performed using a normal thyroid and a representative papillary carcinoma case. The intensity and proportion of the immunostained tumor cells were graded semiquantitatively. The grades of the intensity and the proportion were then summed to provide an immunohistochemical score. There was a variation in the staining intensity and proportion. The iNOS expression was low in normal follicular epithelia. Inducible nitric oxide synthase is present in the majority of thyroid tumor cells, including follicular adenomas, papillary carcinomas, follicular carcinomas, medullary carcinomas, and anaplastic carcinomas. Relatively low expression was shown in follicular neoplasms. Only a few inflammatory cells in the stroma were immunoreactive. These results suggest that iNOS may have a role in tumorigenesis, and iNOS in human thyroid carcinoma is mostly derived from tumor cells not from macrophages.

5-Fluorouracil inhibits nitric oxide production through the inactivation of IkappaB kinase in stomach cancer cells

The antimetabolite 5-fluorouracil (5-FU) is one of the more prominent clinical antitumor agents available for the treatment of stomach and colorectal cancers. In the present study, we characterized the effects of 5-FU on nitric oxide (NO) production by cells from the stomach cancer cell line NCI-N87. A cytokine mixture [interleukin (IL)-1beta/interferon (IFN)-gamma] increased the production of NO by stomach cancer cells in a concentration- and time-dependent manner. Pretreatment with 5-FU inhibited the production of NO that was stimulated by the cytokine mixture and reduced the expression of iNOS. The cytokine mixture activated nuclear factor kappaB (NF-kappaB) in a concentration- and time-dependent manner, which was blocked by 5-FU pretreatment. The pretreatment with 5-FU stabilized IkappaBalpha and inactivated IkappaB kinase. Collectively, these data suggest that the efficacy of 5-FU may include the inactivation of IkappaB kinase and the inhibition of NO production.

Relationship between the expression of iNOS, VEGF, tumor angiogenesis and gastric cancer

AIM: To investigate the relationship between the expression of inducible nitric oxide synthase (iNOS), vascular endothelial growth factor (VEGF), the microvascular density (MVD) and the pathological features and clinical staging of gastric cancer.

METHODS: Immunohistochemical staining was used for detecting the expression of iNOS and VEGF in 46 resected specimens of gastric carcinoma; the monoclonal antibody against CD34 was used for displaying vascular endothelial cells, and MVD was detected by counting of CD34-positive vascular endothelial cells.

RESULTS: Of 46 resected specimens of gastric carcinoma, the rates of expressions of iNOS and VEGF were 58.70% and 76.09%, respectively, and MVD averaged 55.59 ± 19.39. Judged by the standard TNM criteria, the rate of expression of iNOS in stage IV (84.46%) was higher than those in stage I, II, III (Fish exact probabilities test, P = 0.019, 0.023 and 0.033, respectively); the rates of expression of VEGF in stage III, IV (76.0%, 92.31%, respectively) were higher than those in stage I, II (Fish exact probabilities test, P = 0.031, 0.017, 0.022 and 0.019). MVDs in stage III, IV (64.72 ± 14.96, 67.09 ± 18.29, respectively) were higher than those in stage I, II (t = 2.378, 4.015, 2.503 and 2.450, P < 0.05, P < 0.001, P < 0.001, P < 0.05, respectively). In 37 gastric carcinoma specimens with lymph node metastasis, MVD (68.69 ± 18.07) and the rates of expression of iNOS and VEGF (70.27%, 83.78%, respectively) were higher than those in the specimens with absence of metastasis (t = 2.205, χ² = 6.3587, χ² = 6.2584, P < 0.01, P < 0.05, P < 0.05, respectively). MVD and the expressions of iNOS and VEGF were not correlated to the location, size or grade of tumor, nor with the depth of invasion of tumor; MVDs in the positive iNOS and VEGF specimens (59.88 ± 18.02, 58.39 ± 17.73, respectively) were higher than those in the negative iNOS and VEGF specimens (χ² = 6.3587 and 6.1574, P < 0.05, P < 0.05, respectively); thus the expressions of iNOS and VEGF was correlated to MVD, but the expression of iNOS was not correlated to that of VEGF. In addition, of the 46 surviving patients, the 5-year survival rate of patients with positive iNOS or VEGF tumors was significantly less than that of patients with negative iNOS-or VEGF tumors (χ² = 4.3842 and 5.4073, P < 0.05, P < 0.05, respectively).

CONCLUSION: The expressions of iNOS and VEGF are closely related to tumor angiogenesis, and are involved in the advancement and the lymph node metastasis; thus MVD and the expressions of iNOS and VEGF may serve indexes for evaluating staging of gastric carcinoma and forecasting its risk of metastasis, which will help establish a comprehensive therapeutical measure of post-operative patients and provide a new approach to tumor therapy.