Expression of inducible nitric oxide synthase and cyclooxygenase-2 in pancreatic adenocarcinoma: Correlation with microvessel density

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.

NO• and Pancreatic Cancer: A Complex Interaction with Therapeutic Potential

SIGNIFICANCE

Pancreatic tumors express high level of nitric oxide synthases (NOSs) in particular inducible (iNOS/NOS2) and endothelial (eNOS/NOS3) forms. However, the role of nitric oxide (NO^•) in the development and progression of pancreatic cancer is not clearly defined. Delineating the NO^•-induced signaling in pancreatic cancer and its potential contribution in disease aggressiveness may provide therapeutic targets to improve survival in this lethal malignancy. Recent Advances: An increased expression of NOS2/iNOS in tumors is associated with poorer survival in early stage resected patients with pancreatic ductal adenocarcinoma (PDAC). Furthermore, genetic deletion of NOS2 enhanced survival in mice with autochthonous PDAC. Additionally, targeting NOS3/eNOS reduced the abundance of precursor lesions in mice, which trended toward improved survival.

CRITICAL ISSUES

The extremely poor prognosis in pancreatic cancer is due to the late diagnosis and lack of effective therapy in advanced disease. One of the most critical issues is to decipher the underlying mechanism of disease aggressiveness and therapeutic resistance for identifying potential therapeutic target and effective treatment. Given the evidence of a strong association between inflammation and pancreatic cancer and clinical evidence, which suggests an association between NOS2 and disease aggressiveness, it is critical to define the role of NO^• signaling in this lethal malignancy.

FUTURE DIRECTIONS

Recent preclinical and clinical evidences indicate a potential therapeutic significance of targeting NO^• signaling in pancreatic cancer. With the emergence of new preclinical models, including the patient-derived organoids, further preclinical evaluation using clinically tested NOS inhibitors is needed for designing future clinical investigation. Antioxid. Redox Signal. 26, 1000-1008.

[Inflammation and Cancer Development in Pancreatic and Biliary Tract Cancer]

Chronic inflammation has been known to be a risk for many kinds of cancers, including pancreatic and biliary tract cancer. Recently, inflammatory process has emerged as a key mediator of cancer development and progression. Many efforts with experimental results have been given to identify the underlying mechanisms that contribute to inflammation-induced tumorigenesis. Diverse inflammatory pathways have been investigated and inhibitors for inflammation-related signaling pathways have been developed for cancer treatment. This review will summarize recent outcomes about this distinctive process in pancreatic and biliary tract cancer. Taking this evidence into consideration, modulation of inflammatory process will provide useful options for pancreatic and biliary tract cancer treatment.

A comparative study of clinicopathological features between chronic cholecystitis patients with and without Helicobacter pylori infection in gallbladder mucosa

BACKGROUND

Helicobacter pylori has been isolated from 10%-20% of human chronic cholecystitis specimens but the characteristics of "Helicobacter pylori positive cholecystitis" remains unclear. This study aims to compare the clinicopathological features between chronic cholecystitis patients with and without Helicobacter pylori infection in gallbladder mucosa.

METHODS

Three hundred and twenty-six chronic cholecystitis patients were divided into two groups according to whether Helicobacter pylori could be detected by culture, staining or PCR for Helicobacter 16s rRNA gene in gallbladder mucosa. Positive samples were sequenced for Helicobacter pylori-specific identification. Clinical parameters as well as pathological characteristics including some premalignant lesions and the expression levels of iNOS and ROS in gallbladder were compared between the two groups.

RESULTS

Helicobacter pylori infection in gallbladder mucosa was detected in 20.55% of cholecystitis patients. These patients had a higher prevalence of acid regurgitation symptoms (p = 0.001), more histories of chronic gastritis (p = 0.005), gastric ulcer (p = 0.042), duodenal ulcer (p = 0.026) and higher presence of Helicobacter pylori in the stomach as compared to patients without Helicobacter pylori infection in the gallbladder mucosa. Helicobacter pylori 16s rRNA in gallbladder and gastric-duodenal mucosa from the same individual patient had identical sequences. Also, higher incidences of adenomyomatosis (p = 0.012), metaplasia (p = 0.022) and higher enhanced expressions of iNOS and ROS were detected in Helicobacter pylori infected gallbladder mucosa (p<0.05).

CONCLUSIONS

Helicobacter pylori infection in gallbladder mucosa is strongly associated with Helicobacter pylori existed in stomach. Helicobacter pylori is also correlated with gallbladder premalignant lesions including metaplasia and adenomyomatosis. The potential mechanism might be related with higher ROS/RNS production but needs further investigation.

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.

Involvement of inflammatory factors in pancreatic carcinogenesis and preventive effects of anti-inflammatory agents

Chronic inflammation is known to be a risk for many cancers, including pancreatic cancer. Heavy alcohol drinking and cigarette smoking are major causes of pancreatitis, and epidemiological studies have shown that smoking and chronic pancreatitis are risk factors for pancreatic cancer. Meanwhile, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) are elevated in pancreatitis and pancreatic cancer tissues in humans and in animal models. Selective inhibitors of iNOS and COX-2 suppress pancreatic cancer development in a chemical carcinogenesis model of hamsters treated with N-nitrosobis(2-oxopropyl)amine (BOP). In addition, hyperlipidemia, obesity, and type II diabetes are also suggested to be associated with chronic inflammation in the pancreas and involved in pancreatic cancer development. We have shown that a high-fat diet increased pancreatic cancer development in BOP-treated hamsters, along with aggravation of hyperlipidemia, severe fatty infiltration, and increased expression of adipokines and inflammatory factors in the pancreas. Of note, fatty pancreas has been observed in obese and/or diabetic cases in humans. Preventive effects of anti-hyperlipidemic/anti-diabetic agents on pancreatic cancer have also been shown in humans and animals. Taking this evidence into consideration, modulation of inflammatory factors by anti-inflammatory agents will provide useful data for prevention of pancreatic cancer.

Nitric oxide synthases, cyclooxygenase-2, nitrotyrosine, and angiogenesis in chondrosarcoma and their relation to prognosis

BACKGROUND

The localization in tumor tissue of various markers by immunohistochemistry can help to establish a diagnosis or predict prognosis. Nitric oxide is associated with tumors and has been studied indirectly by nitrotyrosine analysis and with use of the enzymes nitric oxide synthase (NOS)1, NOS2, and NOS3. Nitric oxide reacts with superoxide anions to yield peroxynitrite, which has toxic effects on genes. Peroxynitrite adds a nitro group to the benzene ring of tyrosine to form nitrotyrosine. The accumulation of nitrotyrosine, a stable product in cells, indicates the formation of peroxynitrite. Nitric oxide stimulates the production of cyclooxygenase-2 (COX-2), which has been associated with angiogenesis in tumors. Neovascularization influences tumor prognosis, as demonstrated by microvessel studies with use of CD34, an immunohistochemical endothelial cell marker. This study examines the expression of these markers in chondrosarcomas and their relation to histological grade and prognosis.

METHODS

Tissue microarrays composed of formalin-fixed tissue samples from 101 patients with chondrosarcoma were immunohistochemically stained to localize NOS1, NOS2, NOS3, COX-2, nitrotyrosine, and CD34. Five samples of normal cartilage were used as controls. Patient demographics, selected surgical variables, and tumor grade were tabulated, and the associations were analyzed. Analyses of local and overall survival rates were performed with use of the Kaplan-Meier method, and multivariable analyses were performed.

RESULTS

There was a significant association of nitrotyrosine, COX-2, and CD34 with histological grades (p = 0.022, p = 0.014, and p = 0.028, respectively), but not with overall prognosis (p = 0.064, p = 0.143, and p = 0.581, respectively). The presence of NOS2 was associated with a lower rate of local disease-free survival (p = 0.038), and positive expressions of NOS1 and NOS2 were associated with decreased overall survival rates (p = 0.007 and p < 0.001, respectively). On multivariable analysis, NOS2 expression demonstrated an independent prognostic impact on local disease-free survival; NOS1 and NOS2 expression was a dependent variable, and their isolated or combined expression was related to lower overall survival rates (p = 0.046 and p = 0.004) (hazard ratio, 3.17 [95% confidence interval, 1.0 to 9.8] and 5.58 [95% confidence interval, 1.7 to 18.0], respectively).

CONCLUSIONS

Immunohistochemical markers may have an independent value in predicting the prognosis for patients with chondrosarcoma.

Targeting nitric oxide for cancer therapy

A blueprint for the ideal anticancer molecule would include most of the properties of nitric oxide (NO•), but the ability to exploit these characteristics in a therapeutic setting requires a detailed understanding of the biology and biochemistry of the molecule. These properties include the ability of NO• to affect tumour angiogenesis, metastasis, blood flow and immuno surveillance. Furthermore NO• also has the potential to enhance both radio- and chemotherapy. However, all of these strategies are dependent on achieving appropriate levels of NO•, since endogenous levels of NO• appear to have a clear role in tumour progression. This review aims to summarize the role of NO• in cancer with particular emphasis on how the properties of NO• can be exploited for therapy.

Anti-inflammatory agents as cancer therapeutics

Cancer prevention sometimes referred to as tertiary prevention or chemoprevention makes use of specific xenobiotics or drugs to prevent, delay, or retard the development of cancer. Over the last two decades or so cancer prevention has made significant strides. For example, prevention of lung cancer through smoking cessation; cervical cancer prevention through regular Pap smear tests; colon cancer prevention through screening colonoscopy; and prostate cancer reductions by prostate-specific antigen measurements in conjunction with regular prostate examinations. The seminal epidemiological observation that nonsteroidal anti-inflammatory drugs (NSAIDs) prevent colon and other cancers has provided the impetus to develop novel chemoprevention approaches against cancer. To that end, a number of "designer drugs" have been synthesized that are in different stages of development, evaluation, and deployment. Some include the cyclooxygenase-2-specific inhibitors (coxibs), nitric oxide-releasing NSAIDs (NO-NSAIDs and NONO-NSAIDs), hydrogen sulfide-releasing NSAIDs, modulators of the lipoxygenase pathway, prostanoid receptor blockers, and chemokine receptor antagonists. In addition to these novel agents, there are also a host of naturally occurring compounds/micronutrients that have chemopreventive properties. This chapter reviews these classes of compounds, their utility and mechanism(s) of action against the background of mediators that link inflammation and cancer.

Prevention and treatment of pancreatic cancer by curcumin in combination with omega-3 fatty acids

Pancreatic cancer BxPC-3 cells were exposed to curcumin, docosahexaenoic acid (DHA), or combinations of both and analyzed for proliferation and apoptosis. Pancreatic tumor xenografts were established by injecting BxPC-3 cells into each flank of nude mice. After the tumors reached a size of approximately 190-200 mm(3), animals were fed diets with or without 2,000 ppm curcumin in 18% corn oil or 15% fish oil + 3% corn oil for 6 more wk before assessing the tumor volume and expression of inducible nitric oxide synthase (iNOS), cyclooxygeanse-2 (COX-2), 5-lipoxinase (5-LOX), and p21. A synergistic effect was observed on induction of apoptosis (approximately sixfold) and inhibition of cell proliferation (approximately 70%) when cells were treated with curcumin (5 microM) together with the DHA (25 microM). Mice fed fish oil and curcumin showed a significantly reduced tumor volume, 25% (P < 0.04) and 43% (P < 0.005), respectively, and importantly, a combination of curcumin and fish oil diet showed > 72% (P < 0.0001) tumor volume reduction. Expression and activity of iNOS, COX-2, and 5-LOX are downregulated, and p21 is upregulated in tumor xenograft fed curcumin combined with fish oil diet when compared to individual diets. The preceding results evidence for the first time that curcumin combined with omega-3 fatty acids provide synergistic pancreatic tumor inhibitory properties.

The role of nitric oxide in mediating tumour blood flow

Nitric oxide (NO) is a ubiquitous molecule with a myriad of physiological and pathophysiological roles. It has numerous direct and indirect effects on tumour vasculature as both a regulatory and effector molecule. NO affects tumour blood flow through its effects on tumour angiogenesis, vascular tone and vascular permeability, partly via its interaction with vascular endothelial growth factor. In this review, the authors examine the basic tenants of NO biology, the association of NO with tumour progression, and the role NO plays in mediating alterations in vascular functions in tumours.

Effect of tanshinone II A on COX-2 expression in hepatocellular carcinoma cell line SMMC-7721

AIM: To observe the effect of Tanshinone II A on the proliferation and apoptosis of human hepatocellular carcinoma cell line SMMC-7721 and its machanism.

METHODS: The human hepatocellular carcinoma cell line SMMC-7721 cultured in vitro was treated with different concentrations (final 0.5 mg/L) Tanshinone II A. The proliferation of the cells was measured by MTT assay, and the apoptosis of the cells was investigated by flow cytometry and transmission electron microscopy (TEM). The expression of Cyclooxygenase-2 (COX-2) was detected by immunocytochemistry. The levels of prostaglandin E2 (PGE2) in medium were measured by radioimmunoassay.

RESULTS: Tanshinone II A inhibited the growth of SMMC-7721 cells in a dose-dependent manner. The inhibitory rate reached the peak (69.3%) after 0.5 mg/L Tanshinone II A was used for 48 h, which was significantly higher than that in the controls (P < 0.01). Typical features of apoptosis as cell shrinkage, nuclear chromatin condensation, fragmentation, and the formation of apoptotic bodies was found by TEM in the cells treated with Tanshinone II A. FCM analysis showed the apoptotic rates for 24, 48 and 72 h were 7.45% ± 0.33%, 6.59% ± 0.45%, and 4.78% ± 1.05%, respectively, when 5 mg/L Tanshinone II A was used, which were markedly higher than those in the controls (all P < 0.01). Both the expression of COX-2 (P < 0.01) and the production of PGE2 (40.18 ± 1.37 μg/L vs 75.31 ± 1.64 μg/L, P < 0.01) were decreased significantly after Tanshinone II A treatment as compared with those in the controls.

CONCLUSION: Tanshinone II A inhibits the proliferation and increases the apoptosis of human hepatocellular carcinoma cell line SMMC-7721 by down-regulation of COX-2 protein expression.

Suppressive effect of an inducible nitric oxide inhibitor, ONO-1714, on AOM-induced rat colon carcinogenesis

The expression of inducible nitric oxide synthase (iNOS) is markedly elevated in rat colon cancers induced by azoxymethane (AOM). In addition, iNOS can be detected in most adenomas and dysplastic aberrant crypt foci (ACF), suggesting that iNOS plays an important role in colon carcinogenesis. In the present study, the effect of an iNOS inhibitor, ONO-1714 ((1S,5S,6R,7R)-7-chloro-3-imino-5-methyl-2-azabicyclo[4.1.0] heptane hydrochloride), on AOM-induced rat colon carcinogenesis was investigated. Male F344 rats were treated with 15 mg/kg body weight of AOM once a week, for 2 weeks. ONO-1714 was given to the rats at doses of 10, 20, 50, and 100 ppm in diet for 4 weeks from the day before the first carcinogen treatment. The number of AOM-induced ACF in the rats receiving 10, 20, 50 and 100 ppm ONO-1714 were 94, 73 (P < 0.05), 71 (P < 0.005), and 53% (P < 0.0005), respectively, of the control value. Moreover, the mean number of aberrant crypts per focus was significantly lowered in 100 ppm ONO-1714 group (P < 0.05). Then, the effects of long-term treatment (32 weeks) with 50 and 100 ppm ONO-1714 on AOM-induced colorectal tumor development were examined. Although incidences and multiplicities of colon tumors did not significantly differ among the groups, number of tumors developing in the middle part of colon were reduced with both 50 and 100 ppm doses (P < 0.05). Furthermore, colon tumor volume tended to be decreased by ONO-1714 treatment, and the number of colon tumors more than 3mm in diameter was significantly lowered in the 100 ppm ONO-1714 group (P < 0.01). These results suggest that iNOS plays roles in both early and late stages of colon carcinogenesis.

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.

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Effects of lipopolysaccharide with L-arginine on proliferation and apoptosis of human hepatocellular carcinomacell line Bel-7402

AIM: To study the effect of endogenous nitric oxide (NO) on the proliferation and apoptosis in human liver carcinoma cell line 7402 through regulation of the speed limit enzyme and the concentration of substrate in the process of No production.

METHODS: The speed limit enzyme in the process of NO production in 7402 cell is inducible nitric oxide synthase (iNOS), and its substrate is L-arginine (L-Arg).The cells were cultured in the Dulbecco's modified Eagle medium, which was without L-Arg. Different concentration of L-Arg was added into the culture medium and lipopolysaccharide (LPS) of 100 ng/L was added at the same time. MTT method was adopted to describe the proliferation of the cells. Immunohistochemical method was performed to determine the expression of iNOS. The TUNEL method was used to detect the apoptosis in situ.

RESULTS: Without change of the expression and activity of iNOS, L-Arg of 0.625 mmol/L produced NO with low concentration, it could promote the proliferation of the cells. On the contrary, L-Arg of 2.5 mmol/L inhibited the proliferation of the cells and improved the apoptotic rate of the cells. LPS of 100 ng/L could promote the expression and activity of iNOS in the cells. The production of NO in unit time was increased if the substrate was enough.

CONCLUSION: Low concentration of NO promotes the proliferation of the cells. High concentration of NO can inhibit the proliferation and promote the apoptosis of the cells. Increasing the production of endogenous NO by stimulating the expression and activity of its own iNOS is an effective way to inhibit the cells proliferation and promote its apoptosis.