Differential requirement of signal pathways for benzo[ a ]pyrene (B[ a ]P)-induced nitric oxide synthase (iNOS) in rat esophageal epithelial cells

Prognostic gene expression profile of colorectal cancer

Colorectal cancer is a major global health burden, with significant heterogeneity in clinical outcomes among patients. Identifying robust prognostic gene expression signatures can help stratify patients, guide treatment decisions, and improve clinical management. This review provides an overview of current prognostic gene expression profiles in colorectal cancer research. We have synthesized evidence from numerous published studies investigating the association between tumor gene expression patterns and patient survival outcomes. The reviewed literature reveals several promising gene signatures that have demonstrated the ability to predict disease-free survival and overall survival in CRC patients, independent of standard clinicopathological risk factors. These genes are crucial in fundamental biological processes, including cell cycle control, epithelial-mesenchymal transition, and immune regulation. The implementation of prognostic gene expression tests in clinical practice holds great potential for enabling more personalized management strategies for colorectal cancer.

S6K2 in Focus: Signaling Pathways, Post-Translational Modifications, and Computational Analysis

S6 Kinase 2 (S6K2) is a key regulator of cellular signaling and is crucial for cell growth, proliferation, and survival. This review is divided into two parts: the first focuses on the complex network of upstream effectors, downstream modulators, and post-translational modifications (PTMs) that regulate S6K2 activity. We emphasize the dynamic nature of S6K2 regulation, highlighting its critical role in cellular homeostasis and its potential as a therapeutic target in diseases like cancer. The second part utilizes in silico analyses, employing computational tools to model S6K2's three-dimensional structure and predict its interaction networks. Molecular dynamics simulations and docking studies reveal potential binding sites and interactions with novel known inhibitors. We also examine the effects of environmental contaminants that potentially disrupt S6K2 function and provide insights into the role of external factors that could impact its regulatory mechanisms. These computational findings provide a deeper understanding of the conformational dynamics of S6K2 and its interactions with its inhibitors. Together, this integrated biochemical and computational approach enhances our understanding of S6K2 regulation and identifies potential new therapeutic strategies targeting S6K2 in the oncology setting.

Associations between inhaled doses of PM2.5-bound polycyclic aromatic hydrocarbons and fractional exhaled nitric oxide

Exposure to fine particulate matter (PM_2.5) is linked to various respiratory outcomes. However, the associations of concentrations of PM_2.5-bound polycyclic aromatic hydrocarbons (PM_2.5-bound PAHs) with airway inflammatory indices remains unclear. To assess effects of short-term exposure to PM_2.5-bound PAHs on fractional exhaled nitric oxide (FeNO), we conducted a pilot study with repeated measures. We recruited 20 postgraduate students in Wuhan city, China, and repeatedly measured outdoor and indoor (including dormitories, offices and laboratories) PM_2.5-bound PAHs concentrations, urinary monohydroxy polycyclic aromatic hydrocarbons (OH-PAHs) and FeNO levels in the four seasons. Subsequently, we estimated inhaled doses of PM_2.5-bound PAHs based on the micro-environmental PM_2.5-bound PAHs concentrations, time-activity patterns and referred inhalation rates. We assessed the association of inhaled doses of PM_2.5-bound PAHs with FeNO using linear mixed-effects regression models. We found the positive associations of urinary ∑OH-PAHs levels with inhaled doses of indoor PM_2.5-bound PAHs (including dormitories and offices) (all p < 0.05). A one-unit increase in inhaled doses of PM_2.5-bound PAHs or in urinary concentrations of ∑OH-PAHs was corresponded to a maximum FeNO increase of 13.5% (95% CI: 5.4, 22.2) at lag2 day or of 6.8% (95% CI: 3.4, 10.2) at lag1 day. Inhaled doses of PM_2.5-bound PAHs or urinary OH-PAHs was positively related to increased FeNO, they may be accepted as a short-term biomarker of exposure to PAHs in air. Exposure to PM_2.5-bound PAHs in indoor air may contribute more to the body burden of PAHs than outdoor air, and exhibited stronger effect on increased FeNO rather than urinary OH-PAHs.

Role of protein kinase N2 (PKN2) in cigarette smoke-mediated oncogenic transformation of oral cells

Smoking is the leading cause of preventable death worldwide. Though cigarette smoke is an established cause of head and neck cancer (including oral cancer), molecular alterations associated with chronic cigarette smoke exposure are poorly studied. To understand the signaling alterations induced by chronic exposure to cigarette smoke, we developed a cell line model by exposing normal oral keratinocytes to cigarette smoke for a period of 12 months. Chronic exposure to cigarette smoke resulted in increased cellular proliferation and invasive ability of oral keratinocytes. Proteomic and phosphoproteomic analyses showed dysregulation of several proteins involved in cellular movement and cytoskeletal reorganization in smoke exposed cells. We observed overexpression and hyperphosphorylation of protein kinase N2 (PKN2) in smoke exposed cells as well as in a panel of head and neck cancer cell lines established from smokers. Silencing of PKN2 resulted in decreased colony formation, invasion and migration in both smoke exposed cells and head and neck cancer cell lines. Our results indicate that PKN2 plays an important role in oncogenic transformation of oral keratinocytes in response to cigarette smoke. The current study provides evidence that PKN2 can act as a potential therapeutic target in head and neck squamous cell carcinoma, especially in patients with a history of smoking.

Evaluation of iNOS Expression in Esophageal Cancer Patients

BACKGROUND

Esophageal cancer is a public health concern around the world; this cancer is the sixth leading cause of death of cancer in the world with about 386,000 deaths per year. Its risk factors include environmental factors such as tobacco smoke, gastroesophageal reflux and genetic changes. iNOS is stated by the effect of various inflammatory factors and is thus called inducible NOS. Investigating iNOS expression is a powerful tool for understanding effective molecular parameters at tissue and cellular responses to external factors. In this research work, iNOS expression in patients with esophageal cancer was studied in Iran.

MATERIALS AND METHODS

15 formalin-fixed and paraffin-embedded (FFPE) esophageal cancer tissue samples and 15 normal FFPE samples were collected from various medical centers (Zabol, Zahedan, Kashan) to measure iNOS expression by real-time reverse transcriptase polymerase chain reaction (real-time RT-PCR). All PCR reactions were conducted by three replicates for iNOS and internal control (β-actin) by 2-ΔΔCT (Livak) method. Differences were measured in target gene expression in patients and control group using the t test. All statistical analyses were done using the SPSS software.

RESULTS

The results showed that there was no significant difference between iNOS expression in the case and control groups (p > 0.05); however, there was an increase in iNOS expression in the case group. On the other hand, there was a significant difference between iNOS expression in males and females in the two groups of healthy subjects and patients, and it was higher in women than in men.

CONCLUSION

Further studies need to be conducted with larger sample sizes and in other populations to validate these findings.

PHLPP2 Downregulation Contributes to Lung Carcinogenesis Following B[a]P/B[a]PDE Exposure

PURPOSE

The carcinogenic capacity of B[a]P/B[a]PDE is supported by epidemiologic studies. However, the molecular mechanisms responsible for B[a]P/B[a]PDE-caused lung cancer have not been well investigated. We evaluated here the role of novel target PHLPP2 in lung inflammation and carcinogenesis upon B[a]P/B[a]PDE exposure.

EXPERIMENTAL DESIGN

We used the Western blotting, RT-PCR, [(35)S]methionine pulse and immunohistochemistry staining to determine PHLPP2 downregulation following B[a]P/B[a]PDE exposure. Both B[a]PDE-induced Beas-2B cell transformation model and B[a]P-caused mouse lung cancer model were used to elucidate the mechanisms leading to PHLPP2 downregulation and lung carcinogenesis. The important findings were also extended to in vivo human studies.

RESULTS

We found that B[a]P/B[a]PDE exposure downregulated PHLPP2 expression in human lung epithelial cells in vitro and in mouse lung tissues in vivo. The ectopic expression of PHLPP2 dramatically inhibited cell transformation upon B[a]PDE exposure. Mechanistic studies showed that miR-205 induction was crucial for inhibition of PHLPP2 protein translation by targeting PHLPP2-3'-UTR. Interestingly, PHLPP2 expression was inversely associated with tumor necrosis factor alpha (TNFα) expression, with low PHLPP2 and high TNFα expression in lung cancer tissues compared with the paired adjacent normal lung tissues. Additional studies revealed that PHLPP2 exhibited its antitumorigenic effect of B[a]P/B[a]PDE through the repression of inflammatory TNFα transcription.

CONCLUSIONS

Our studies not only first time identify PHLPP2 downregulation by lung carcinogen B[a]P/B[a]PDE, but also elucidate a novel molecular mechanisms underlying lung inflammation and carcinogenesis upon B[a]P/B[a]PDE exposure.

Luteolin inhibits Cr(VI)-induced malignant cell transformation of human lung epithelial cells by targeting ROS mediated multiple cell signaling pathways

Hexavalent chromium [Cr(VI)] is a well-known human carcinogen associated with the incidence of lung cancer. Inhibition of metal induced carcinogenesis by a dietary antioxidant is a novel approach. Luteolin, a natural dietary flavonoid found in fruits and vegetables, possesses potent antioxidant and anti-inflammatory activity. We found that short term exposure of human bronchial epithelial cells (BEAS-2B) to Cr(VI) (5μM) showed a drastic increase in ROS generation, NADPH oxidase (NOX) activation, lipid peroxidation, and glutathione depletion, which were significantly inhibited by the treatment with luteolin in a dose dependent manner. Treatment with luteolin decreased AP-1, HIF-1α, COX-2, and iNOS promoter activity induced by Cr(VI) in BEAS-2B cells. In addition, luteolin protected BEAS-2B cells from malignant transformation induced by chronic Cr(VI) exposure. Moreover, luteolin also inhibited the production of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α) and VEGF in chronic Cr(VI) exposed BEAS-2B cells. Western blot analysis showed that luteolin inhibited multiple gene products linked to survival (Akt, Fak, Bcl-2, Bcl-xL), inflammation (MAPK, NF-κB, COX-2, STAT-3, iNOS, TNF-α) and angiogenesis (HIF-1α, VEGF, MMP-9) in chronic Cr(VI) exposed BEAS-2B cells. Nude mice injected with BEAS-2B cells chronically exposed to Cr(VI) in the presence of luteolin showed reduced tumor incidence compared to Cr(VI) alone treated group. Overexpression of catalase (CAT) or SOD2, eliminated Cr(VI)-induced malignant transformation. Overall, our results indicate that luteolin protects BEAS-2B cells from Cr(VI)-induced carcinogenesis by scavenging ROS and modulating multiple cell signaling mechanisms that are linked to ROS. Luteolin, therefore, serves as a potential chemopreventive agent against Cr(VI)-induced carcinogenesis.

Detection of key enzymes, free radical reaction products and activated signaling molecules as biomarkers of cell damage induced by benzo[a]pyrene in human keratinocytes

Benzo[a]pyrene (BaP) is a known carcinogenic and cell damaging agent. The underlying cell damaging pathomechanisms have not been totally revealed. Especially BaP-related induction of oxidative and nitrosative stress has not been previously investigated in detail. The presented study investigated these effects in order to elucidate the pathomechanism and as well to identify potential biological markers that may indicate a BaP exposure. Human immortalized keratinocytes (HaCaT cells) were exposed to BaP (1 μM) for either 5 min or 6 h, respectively. BaP-induced cellular damage was evaluated by immunocytochemistry analysis of multiple signaling cascades (e.g. apoptosis, Akt, MAPK, NOS, nitrotyrosine and 8-isoprostane formation), detection of nitrosative stress using diaminofluorescein (DAF-FM) and oxidative stress using 3' -(p-aminophenyl)fluorescein (APF). Our results show that BaP exposure significantly enhanced NO and ROS productions in HaCaT cells. BaP led to eNOS-phosphorylation at Ser(1177), Thr(495) and Ser(116) residues. Using specific inhibitors, we found that the Erk1/2 pathways seemed to have strong impact on eNOS phosphorylation. In addition, BaP-induced apoptosis was observed by caspase-3 activation and PARP cleavage. Our results suggest that BaP mediates its toxic effect in keratinocytes through oxidative and nitrosative stress which is accompanied by complex changes of eNOS phosphorylation and changes of Akt and MAPK pathways.

The role of inflammation in HPV infection of the Oesophagus

BACKGROUND

Several human cancers are known to be associated with inflammation and/or viral infections. However, the influence of tumour-related inflammation on viral uptake is largely unknown. In this study we used oesophageal squamous cell carcinoma (OSCC) as a model system since this type of cancer is associated with chronic irritation, inflammation and viral infections. Although still debated, the most important viral infection seems to be with Human Papillomavirus (HPV). The present study focused on a possible correlation between inflammation, OSCC development and the influence of HPV infection.

METHODS

A total of 114 OSCC biopsies and corresponding normal tissue were collected at Groote Schuur Hospital and Tygerberg Hospital, Cape Town (South Africa), that were subjected to RNA and DNA isolation. RNA samples were analysed by quantitative Light Cycler RT-PCR for the expression of selected genes involved in inflammation and infection, while conventional PCR was performed on the DNA samples to assess the presence of integrated viral DNA. Further, an in vitro infection assay using HPV pseudovirions was established to study the influence of inflammation on viral infectivity using selected cell lines.

RESULTS

HPV DNA was found in about 9% of OSCC patients, comprising predominantly the oncogenic type HPV18. The inflammatory markers IL6 and IL8 as well as the potential HPV receptor ITGA6 were significantly elevated while IL12A was downregulated in the tumour tissues. However, none of these genes were expressed in a virus-dependent manner. When inflammation was mimicked with various inflammatory stimulants such as benzo-α-pyrene, lipopolysaccharide and peptidoglycan in oesophageal epithelial cell lines in vitro, HPV18 pseudovirion uptake was enhanced only in the benzo-α-pyrene treated cells. Interestingly, HPV pseudovirion infectivity was independent of the presence of the ITGA6 receptor on the surface of the tested cells.

CONCLUSION

This study showed that although the carcinogen benzo-α-pyrene facilitated HPV pseudovirion uptake into cells in culture, HPV infectivity was independent of inflammation and seems to play only a minor role in oesophageal cancer.

Silymarin attenuates benzo(a)pyrene induced toxicity by mitigating ROS production, DNA damage and calcium mediated apoptosis in peripheral blood mononuclear cells (PBMC)

Benzo(a)pyrene (B(a)P), which is the most studied member of PAH family is released into the environment (air, water and soil) from natural and man-made sources including industrial and automobile exhaust fumes. Since B(a)P is an omnipresent environmental pollutant and is believed to be a risk factor for human chemical carcinogenesis, it is important to identify potent naturally occurring/synthetic agents that could modulate B(a)P-induced toxicity. The present study explores the effect of the flavonoid silymarin (2.4mg/ml) in counteracting the toxicity of B(a)P (1μM) in PBMC. Flourimetry and Confocal Laser Scanning Microscopy results showed that silymarin reduces the B(a)P induced ROS production and DNA damage. Atomic Absorption Spectroscopy analysis and fluorescent microscopic pictures proved that silymarin reduces the increased intracellular calcium and apoptosis induction during B(a)P treatment. Furthermore, silymarin did not show any inhibition for CYP1B1 activity at transcriptional level by semiquantitative RT PCR but it affects the catalytic activity of Phase I CYP1A1/CYP1B1 enzyme (EROD assay) during B(a)P treatment. The findings reveal that silymarin possesses substantial protective effect against B(a)P induced DNA damage and calcium mediated apoptosis by inhibiting the catalytic activity of CYP1B1 and maintaining the intracellular calcium dysregulation; hence, it could be considered as a potential protective agent for environmental contaminant induced immunotoxicity.

Nitric oxide synthase (eNOS4a/b) gene polymorphism is associated with tumor recurrence and progression in superficial bladder cancer cases

PURPOSE

We investigated the relationship between the distribution of the eNOS4a/b polymorphism and the clinical features of superficial bladder cancer.

MATERIALS AND METHODS

This study included 201 healthy controls with a mean ± SD age of 62.35 ± 7.96 years and 123 patients with a mean age of 64.03 ± 11.00 years diagnosed with histopathologically confirmed superficial bladder cancer. The eNOS4a/b polymorphism genotype (aa, bb or ab) was identified by polymerase chain reaction. Blood glutathione and plasma malondialdehyde levels were measured by spectrophotometry as an indicator of oxidative stress. We estimated total plasma levels of nitric oxide metabolites using a colorimetric assay kit.

RESULTS

There were no significant differences in age or body mass index between patients and controls. Malondialdehyde and nitric oxide metabolite levels were statistically significantly increased (p = 0.000 and 0.024, respectively) and glutathione levels were decreased (p = 0.000) in patients with superficial bladder cancer. The bb genotype of the eNOS4a/b polymorphism is the most frequent one in the Turkish population and the aa genotype was significantly more common in patients with superficial bladder cancer (p = 0.000). Also, the aa plus ab genotype was significantly more common in patients with high grade tumors (p = 0.013) and in those with more progression to muscle invasive disease (p = 0.000). This genotype was also a significant independent risk factor for recurrence after adjusting for smoking status, stage, grade and the presence of carcinoma in situ on logistic regression analyses (OR 3.095, 95% CI 1.21-7.86, p = 0.018).

CONCLUSIONS

The current study suggests that a genotype containing the a allele of the eNOS4a/b polymorphism may be a risk factor for bladder cancer. Additionally, patients harboring the aa plus ab genotype are more likely to experience tumor recurrence and progression.

Aryl hydrocarbon receptor in association with RelA modulates IL-6 expression in non-smoking lung cancer

Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that is activated by cigarette smoke. Previously, we demonstrated that AhR is overexpressed in lung adenocarcinomas (ADs). In this study we observed that AhR expression is significantly correlated with nuclear RelA (a nuclear factor-κB (NFκB) subunit) and cytosolic interleukin-6 (IL-6) in 200 non-small cell lung cancer patients, especially among never smokers. Overexpression of AhR increased IL-6 expression in H1355 cells and immortalized human bronchial epithelial cells BEAS-2B. As NFκB inhibitor and knockdown RelA expression greatly reduced constitutive AhR-induced IL-6 expression, we hypothesized that AhR expression, in the absence of exogenous ligand, is able to modulate NFκB activity and subsequently upregulate IL-6 expression, thus promoting the development of lung AD. Specifically, AhR overexpression significantly increased NFκB activity, whereas interference with AhR expression significantly reduced NFκB activity and IL-6 expression in H1355 cells. We demonstrated that AhR associates with RelA in the cytosol and nucleus of human lung cells. Furthermore, AhR overexpression enhanced nuclear localization of AhR and RelA, and increased the association of AhR-RelA with the NFκB response element of the IL-6 promoter. However, p50 was not involved. Our results indicate that AhR, without exposure to a ligand, associates with RelA, which then positively modulates NFκB activity and then upregulates IL-6 expression in human lung cells. Thus we have identified a new mechanism for lung tumorigenesis in non-smokers.

ΔNp63α/IRF6 interplay activates NOS2 transcription and induces autophagy upon tobacco exposure

Tobacco-induced oxidative stress leads to chronic inflammation and is implicated in the development of many human epithelial cancers, including head and neck cancer. Cigarette smoke exposure was shown to induce the expression of the ΔNp63α and nitric oxide synthase (NOS)-2 in head and neck squamous cell carcinoma cells and immortalized oral keratinocytes. The NOS2 promoter was found to contain various cognate sequences for several transcription factors including interferon regulatory factor (IRF)-6 and p63, which were shown in vivo binding to the NOS2 promoter in response to smoke exposure. Small interfering (si)-RNAs against both ΔNp63α and IRF6 decreased the induction of NOS2 promoter-driven reporter luciferase activity and were shown to inhibit NOS2 activity. Furthermore, both mainstream (MSE) and sidestream (SSE) smoking extracts induced changes in expression of autophagic marker, LC3B, while siRNA against ΔNp63α, IRF6 and NOS2 modulated these autophagic changes. Overall, these data support the notion that ΔNp63α/IRF6 interplay regulates NOS2 transcription, thereby underlying the autophagic-related cancer cell response to tobacco exposure.

Cigarette smoking, cyclooxygenase-2 pathway and cancer

Cigarette smoking is a major cause of mortality and morbidity worldwide. Cyclooxygenase (COX) and its derived prostanoids, mainly including prostaglandin E2 (PGE2), thromboxane A2 (TxA2) and prostacyclin (PGI2), have well-known roles in cardiovascular disease and cancer, both of which are associated with cigarette smoking. This article is focused on the role of COX-2 pathway in smoke-related pathologies and cancer. Cigarette smoke exposure can induce COX-2 expression and activity, increase PGE2 and TxA2 release, and lead to an imbalance in PGI2 and TxA2 production in favor of the latter. It exerts pro-inflammatory effects in a PGE2-dependent manner, which contributes to carcinogenesis and tumor progression. TxA2 mediates other diverse biologic effects of cigarette smoking, such as platelet activation, cell contraction and angiogenesis, which may facilitate tumor growth and metastasis in smokers. Among cigarette smoke components, nicotine and its derived nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are the most potent carcinogens. COX-2 and PGE2 have been shown to play a pivotal role in many cancers associated with cigarette smoking, including cancers of lung, gastric and bladder, while the information for the role of TxA2 and PGI2 in smoke-associated cancers is limited. Recent findings from our group have revealed how NNK influences the TxA2 to promote the tumor growth. Better understanding in the above areas may help to generate new therapeutic protocols or to optimize the existing treatment strategy.

Growth hormone releasing hormone induces the expression of nitric oxide synthase

Growth hormone releasing hormone (GHRH) and its receptors are expressed in a wide variety of human tumours and established cancer cell lines and are involved in carcinogenesis. In addition, GHRH antagonists exert an antitumour activity in experimental cancer models. Recent studies indicate that the mechanisms involved in the mediation of the effects of GHRH include the regulation of the metabolism of the reactive oxygen species. This work demonstrates the expression of GHRH receptors and GHRH in the A549 human lung cancer cell line and shows that the mitogenic effect of GHRH in these cells is dependent on the activation of the extracellular receptor kinase (ERK)1/2 pathway. The action of GHRH can be suppressed by GHRH antagonist MZ-5-156 and mitogen activated protein kinase (MAPK) inhibitor PD 098059. These results are reflected in the effect in the proliferating cell nuclear antigen. In addition, our study shows that GHRH increases the expression of the inducible nitric oxide synthase, an enzyme which is strongly involved in various human diseases, including cancer and augments key intracellular regulators of its expression, such as pNF (nuclear factor)κBp50 and cyclooxygenase 2. GHRH antagonist MZ-5-156 counteracts the effects of GHRH in these studies, indicating that this class of peptide antagonists may be useful for the treatment of diseases related to increased oxidative and nitrosative stress.

Cigarette smoke inhibits endometrial epithelial cell proliferation through a nitric oxide-mediated pathway

OBJECTIVE

To determine the direct effects of cigarette smoke (CS) on human endometrial surface epithelial cell line proliferation.

DESIGN

In vitro study using HES cells and primary human endometrial cells.

SETTING

University-based academic center.

PATIENT(S)

Premenopausal women in the proliferative phase of the cycle.

INTERVENTION(S)

The HES cells and primary human endometrial cells were exposed to cigarette smoke-saturated solution.

MAIN OUTCOME MEASURE(S)

Cell proliferation and expression of different isoforms of nitric oxide synthase.

RESULT(S)

Cigarette smoke inhibited HES cell proliferation in a dose- and time-dependant manner. The inhibitory effect of CS was blocked by hemoglobin and enhanced by L-arginine (L-Arg). Cigarette smoking and nicotine stimulated the expression of endothelial NO synthase (eNOS) and inducible NO synthase (iNOS) whereas benzo[a]pyrene (BP) only stimulated the expression of eNOS in HES cells. Cigarette smoke stimulated the expression of eNOS/iNOS in primary human endometrial cells, comprised of epithelial and stromal cells. The effect of CS on eNOS/iNOS expression in HES cells was blocked by ascorbic acid but not by glutathione.

CONCLUSION(S)

Cigarette smoke inhibits endometrial cell proliferation through a nitric oxide-mediated pathway.

Evaluation of 8-hydroxydeoxyguanosine, thiobarbituric acid-reactive substances and total antioxidant status as possible disease markers in oesophageal malignancies

OBJECTIVES

Evaluation of oxidative stress and diagnostic utility of its markers in oesophageal squamous cell carcinoma (OSCC).

DESIGN

Serum 8-hydroxydeoxyguanosine, thiobarbituric acid-reactive substances (TBARS) and total antioxidant status (TAS) were measured in OSCC (n=75), non-malignant oesophageal diseases (n=30), and healthy subjects (n=79). Three months following oesophagectomy the measurements were repeated.

RESULTS

Exclusively in OSCC, 8-hydroxydeoxyguanosine and TBARS were elevated. TAS was reduced in non-malignancies compared to controls, and in OSCC compared to non-malignancies and controls. Only 8-hydroxydeoxyguanosine was associated with disease progression, lymph node involvement in particular. All indices were good indicators of cancer presence (ROC analysis) and normalized following oesophagectomy. A positive linear relationship between 8-hydroxydeoxyguanosine and TBARS, and negative non-linear between TAS and both 8-hydroxydeoxyguanosine and TBARS was demonstrated.

CONCLUSION

OSCC is associated with oxidative stress, attenuated following oesophagectomy. Consumption of serum antioxidants prevents accumulation of oxidatively modified molecules in non-malignancies. High accuracy of oxidative stress markers in indicating cancer presence warrants further investigation on their possible application as discriminatory markers and in monitoring treatment efficacy.

Inducible nitric oxide synthase, nitrotyrosine and p53 mutations in the molecular pathogenesis of Barrett's esophagus and esophageal adenocarcinoma

Nitric oxide (NO) has been implicated as a potential causative factor for endogenous p53 mutations in gastrointestinal malignancy. To investigate the role of NO in esophageal adenocarcinoma (EADC), we studied patterns of p53 mutations, expression of inducible nitric oxide synthase (iNOS) and the tissue accumulation of nitrotyrosine (NTS), a stable reaction product of NO and a marker for cellular protein damage, in human premalignant and malignant esophageal epithelia. Tissues were obtained from patients with gastroesophageal reflux disease (GERD)-induced esophagitis (n = 76), Barrett's esophagus (BE; n = 119) and primary EADC (n = 54). DNA sequencing was used to characterize p53 mutations, RT-PCR to study iNOS mRNA expression, and immunohistochemistry to study NTS. Relative to self-matched normal epithelia, a progressive increase in iNOS mRNA expression was seen in GERD (30%; 23/76), BE (48%; 57/119), and EADC (63%; 34/54) tissues (P < 0.001). Among patients with EADC, elevated levels of NTS immunoreactivity were more frequent in tumors with p53 mutations (11/21; 52%) compared with tumors with wild-type p53 (9/33; 27%; P = 0.063), and specifically in tumors with p53 mutations at CpG dinucleotides (10/12; 83%) compared with non-CpG p53 mutations (1/9; 11%; P = 0.008). The increasing frequency of iNOS (mRNA) overexpression in GERD, BE and EADC supports the hypothesis that an active inflammatory process, most likely a consequence of GERD, underlies molecular progression to EADC. The highly significant association between NTS, reflecting chronic NO-induced cellular protein damage, and endogenous p53 mutations at CpG dinucleotides, provides further evidence for a molecular link between chronic inflammation and esophageal malignancy.

Inducible nitric oxide synthase promoter polymorphism, cigarette smoking, and urothelial carcinoma risk

OBJECTIVES

Bladder carcinoma has a high inducible nitric oxide synthase (iNOS) content, and a highly polymorphic (CCTTT)n repeat in the iNOS promoter region has been identified. We explored whether this iNOS promoter polymorphism and cigarette smoking are associated with urothelial carcinoma (UC) risk.

METHODS

A total of 250 patients with pathologically confirmed UC and 250 unrelated noncancer controls were serially recruited at the Chia Yi Christian Hospital from August 2002 to May 2005. Multivariate logistic regression analysis was used to calculate the odds ratio and 95% confidence interval (CI).

RESULTS

A significantly increased UC risk was found in those who had smoked more than 30 years (odds ratio 2.4, 95% CI 1.5 to 4.2). The study subjects carrying the 12-repeat allele had a significantly increased UC risk (odds ratio 1.7, 95% CI 1.1 to 2.5). We also found the investigated polymorphism was related to clinical stage (P = 0.043). Of those who had ever smoked, those with the short/long (S/L) and long/long (L/L) genotypes (S, 9 to 11 repeats; L, 12 to 18 repeats) and the 12-repeat allele had a significantly increased UC risk of 3.5 (95% CI 1.7 to 7.3) and 4.5 (95% CI 2.2 to 8.9), respectively. Of the study subjects who had smoked longer than 30 years, those with S/L and L/L genotypes and the 12-repeat allele had significantly increased UC risks of 2.4 (95% CI 1.3 to 4.7) and 3.8 (95% CI 1.8 to 8.0), respectively.

CONCLUSIONS

These findings suggest that the polymorphic (CCTTT)n repeat in the iNOS promoter region might be involved in the development of UC, especially in those who have ever smoked.

Benzo[a]pyrene diol-epoxide (B[a]PDE) upregulates COX-2 expression through MAPKs/AP-1 and IKKbeta/NF-kappaB in mouse epidermal Cl41 cells

Benzo[alpha]pyrene-7,8-diol-9,10-epoxide (B[a]PDE), the major metabolite of benzo[a]pyrene (B[a]P), shows an ultimate complete carcinogen in various animals and is a causative agent for human cancers. However, its effects on the activation of signal pathways and the expression of genes involved in its carcinogenic effect remain largely unknown. In this study, the effects of B[a]PDE on induction of cyclooxygenase (COX)-2 and the signal pathways leading to the induction were investigated. Treatment of mouse epidermal Cl41 cells with B[a]PDE caused an increase in the expression of COX-2 at both transcription and protein levels, while its parental compound B[a]P did not show significant inductive effect. The COX-2 induction by B[a]PDE was dependent on the activation of mitogen-activated protein kinases (MAPK)s/activation protein (AP)-1 pathway, because inhibition of AP-1 by either overexpression of TAM67 (dominant negative mutant of c-jun), or pretreatment of cells with PD98059 (MEK1/2-ERKs pathway inhibitor) or SB202190 (p38K inhibitor), markedly inhibited B[a]PDE-induced COX-2 expression. In addition, impairment of NF-kappaB pathway by either NEMO-BDBP (an NF-kappaB specific inhibitor) or IkappaB kinase (IKK)beta-KM (dominant negative mutant of IKKbeta) also caused marked reduction of COX-2 induction by B[a]PDE. In contrast, inhibition of nuclear factor of activated T cells (NFAT) with FK506, did not show any effect on B[a]PDE-induced COX-2 expression. Collectively, these data indicate that exposure of Cl41 cells to B[a]PDE can induce COX-2 expression by increasing its transcription, which requires the activation of MAPKs/AP-1 and IKKbeta/NF-kappaB pathways, but not NFAT pathway. In view of the importance of COX-2 in carcinogenesis, we anticipate that the induction of COX-2 by B[a]PDE may coordinate its mutagenic effects to facilitate the development of skin cancer.

Essential roles of ERKs and p38K in up-regulation of GST A1 expression by Maotai content in human hepatoma cell line Hep3B

It is widely accepted that the consumption of alcohol may lead to hepatic injuries such as hepatic fibrosis and cirrhosis. However, consumption of Maotai, one of the famous liquors in China, is found to have no obvious relevance with hepatic injury as ordinary white wine does in both epidemiological and histopathological studies. Present study used human hepatoma cell line Hep3B to address the mechanisms involved in the resistance of alcohol-induced hepatic injury by Maotai liquor. We found that exposure of Hep3B cells to Maotai residue without ethanol (MRWE) resulted in the increased GST A1 anti-oxidant responsive element (ARE) transcriptional expression, while MRWE treatment did not affect Nrf-2-dependent transcriptional activity. Those findings were further confirmed at all time points and doses tested, suggesting that GST A1 transcription was regulated by MRWE via an Nrf-2-independent pathway. Consistent with GST A1 induction, the phosphorylation of c-Jun, extracellular signal-regulated kinases (ERKs) and p38 kinase (p38 K), were also observed in MRWE-treated Hep3B cells. Furthermore, pretreatment of cells with either PD98059 (an inhibitor specific for MEK1/2-ERKs pathway) or SB202190 (an inhibitor specific for p38 K) led to a significant decrease in the induction of GST A1 transcriptional expression by MRWE treatment. Our results indicate that certain content in MRWE is able to induce GST A1 ARE transcriptional expression, which may provide protective effects for hepatic cells by antagonizing the oxidative stress derived from ethanol via an ERKs- and p38 K-dependent pathway.

Involvement of endogenous nitric oxide in myeloperoxidase mediated benzo(a)pyrene induced polymorphonuclear leukocytes injury

The present study was undertaken to investigate the involvement of nitric oxide in the augmentation of benzo(a)pyrene induced cellular injury in polymorphonuclear leukocytes (PMNs). Polymorphs were isolated from the blood collected from Wistar rats treated with and without benzo(a)pyrene (50mg/kg, i.p.) through cardiac puncture. Catalase, superoxide dismutase (SOD), glutathione-s-transferase (GST), myeloperoxidase (MPO) and nitrite content were estimated in PMNs using standard procedures. Inducible nitric oxide synthase (iNOS) and cytochrome P-4501A1 (CYP1A1) expression in PMNs were also analyzed in presence or absence of nitric oxide synthase (NOS) inhibitors, aminoguanidine (AG, 5mM) and L-NG nitro L-arginine methyl ester (L-NAME, 1mM). A significant augmentation was observed in the nitrite content, activities of superoxide dismutase, MPO and GST and the expressions of iNOS and CYP1A1, however, catalase activity was attenuated in PMNs of benzo(a)pyrene treated rats as compared with their respective controls. AG and L-NAME resulted in a significant attenuation in nitrite content, MPO activity and iNOS expression; however, no significant alteration was observed in CYP1A1 expression. CYP1A1 inhibitor alpha-naphthoflavone inhibited the expression of iNOS in PMNs of benzo(a)pyrene treated animals significantly. The results obtained thus suggest that CYP1A1 induces iNOS expression leading to the generation of endogenous nitric oxide (NO) that could be responsible for the augmentation of myeloperoxidase-mediated benzo(a)pyrene-induced injury in PMNs.

Gaseous nitrogen oxide repressed benzo[a]pyrene-induced human lung fibroblast cell apoptosis via inhibiting JNK1 signals

Benzo[a]pyrene (B[a]P) is present in environmental pollution and cigarette smoke. B[a]P has been shown to induce apoptosis in hepatoma cells, human B cells, human ectocervical cells, macrophages, and rat lungs. Nitrogen oxides (NOx) are the other important indoor and outdoor air pollutants. Many studies have indicated that NO gas causes lung tissue damage both by its oxidative properties and free radicals. In our previous study we demonstrated that NO gas induced proliferation of human lung fibroblast MRC-5 cells. In this study we showed that NO gas inhibits B[a]P-induced MRC-5 cells apoptosis by cell cycle analysis. Western blot data revealed that NO gas increased the expressions of anti-apoptosis proteins (Bcl-2 and Mcl-1) and decreased the expression of apoptosis proteins (Bax, t-Bid, cytochrome c, FasL, and caspases) after B[a]P treatment. We further clarified that B[a]P-induced MRC-5 cell apoptosis via JNK1/FasL and JNK1/p53 signals. In conclusion, NO gas inhibited B[a]P-induced MRC-5 cells apoptosis via inhibition of JNK1 apoptosis pathway and induction of Bcl-2 and Mcl-1 anti-apoptosis pathway.