Increased cyclooxygenase 2 (COX-2) expression occurs frequently in precursor lesions of human adenocarcinoma of the lung

Cyclooxygenase-2 up-regulates vascular endothelial growth factor via a protein kinase C pathway in non-small cell lung cancer

Background

Vascular endothelial growth factor (VEGF) expression is up-regulated via a cyclooxygenase-2 (COX-2)-dependent mechanism in non-small cell lung cancer (NSCLC), but the specific signaling pathway involved is unclear. Our aim was to investigate the signaling pathway that links COX-2 with VEGF up-regulation in NSCLC.

Material and methods

COX-2 expression in NSCLC samples was detected immunohistochemically, and its association with VEGF, microvessel density (MVD), and other clinicopathological characteristics was determined. The effect of COX-2 treatment on the proliferation of NSCLC cells (A549, H460 and A431 cell lines) was assessed using the tetrazolium-based MTT method, and VEGF expression in tumor cells was evaluated by flow cytometry. COX-2-induced VEGF expression in tumor cells was monitored after treatment with inhibitors of protein kinase C (PKC), PKA, prostaglandin E2 (PGE₂), and an activator of PKC.

Results

COX-2 over-expression correlated with MVD (P = 0.036) and VEGF expression (P = 0.001) in NSCLC samples, and multivariate analysis demonstrated an association of VEGF with COX-2 expression (P = 0.001). Exogenously applied COX-2 stimulated the growth of NSCLCs, exhibiting EC₅₀ values of 8.95 × 10^-3, 11.20 × 10^-3, and 11.20 × 10^-3 μM in A549, H460, and A431 cells, respectively; COX-2 treatment also enhanced tumor-associated VEGF expression with similar potency. Inhibitors of PKC and PGE₂ attenuated COX-2-induced VEGF expression in NLCSCs, whereas a PKC activator exerted a potentiating effect.

Conclusion

COX-2 may contribute to VEGF expression in NSCLC. PKC and downstream signaling through prostaglandin may be involved in these COX-2 actions.

Evaluation of the role of oxidative stress in chemopreventive action of fish oil and celecoxib in the initiation phase of 7,12-dimethyl benz(α)anthracene-induced mammary carcinogenesis

Cyclooxygenase-2 (COX-2) enzyme plays an important role in cancer development. COX-2 inhibition by non-steroidal anti-inflammatory drugs is a useful approach for cancer prevention, but its usage has been associated with side effects. n-3 polyunsaturated fatty acids also exhibit a chemopreventive effect mediated by COX-2 inhibition. Therefore, the present study was designed to evaluate the effect of combined dosage of celecoxib and fish oil in experimental mammary carcinogenesis. Female Wistar rats were distributed as control, 7,12-dimethyl benz(α)anthracene (DMBA) treated, celecoxib + fish oil (20 mg/kg b.w. + 0.5 ml), celecoxib + fish oil (30 mg/kg b.w. + 0.25 ml), and their corresponding controls treated with fish oil or celecoxib only. The treatment was given for 7 days, and on the 8th day animals of all the groups except the control group received DMBA orally and sacrificed after 90 days. The histopathology, DNA fragmentation, total sialic acid (TSA), lipid-associated sialic acid (LASA), and oxidative stress were measured in mammary tissue and liver mitochondrial fraction. The results showed ductal hyperplasia and an increase in TSA, LASA, lipid peroxidation, and nitrite levels with a decrease in the antioxidants on DMBA treatment. Pretreatment with celecoxib and fish oil in DMBA-treated animals led to normal histology, increase in DNA fragmentation, and decrease in TSA and LASA levels with reduced oxidative stress, and the effect was more pronounced than animals pretreated with either celecoxib/fish oil alone suggesting a synergistic effect of the two regimens. To conclude, a combination of celecoxib and fish oil is a better strategy for cancer chemoprevention than celecoxib/fish oil alone.

Design, synthesis, and biological evaluation of ketoprofen analogs as potent cyclooxygenase-2 inhibitors

A new series of ketoprofen analogs were synthesized to evaluate their biological activities as selective cyclooxygenase-2 (COX-2) inhibitors. In vitro COX-1 and COX-2 inhibition studies showed that all compounds were potent and selective inhibitors of the COX-2 isozyme with IC(50) values in the highly potent 0.057-0.085 microM range, and COX-2 selectivity indexes in the 115 to >1298.7 range. Compounds possessing azido pharmacophore group (8a and 8b) exhibited highly COX-2 inhibitory selectivity and potency even more than reference drug celecoxib. Molecular modeling studies indicated that the azido substituent can be inserted deeply into the secondary pocket of COX-2 active site for interactions with Arg(513).

Redox Factor-1 Inhibits Cyclooxygenase-2 Expression via Inhibiting of p38 MAPK in the A549 Cells

In this study, we evaluated the role of apurinic/apyrimidinic endonuclease1/redox factor-1 (Ref-1) on the tumor necrosis factor-alpha (TNF-alpha) induced cyclooxygenase-2 (COX-2) expression using A549 lung adenocarcinoma cells. TNF-alpha induced the expression of COX-2 in A549 cells, but did not induce BEAS-2B expression. The expression of COX-2 in A549 cells was TNF-alpha dose-dependent (5~100 ng/ml). TNF-alpha-stimulated A549 cells evidenced increased Ref-1 expression in a dose-dependent manner. The adenoviral transfection of cells with AdRef-1 inhibited TNF-alpha-induced COX-2 expression relative to that seen in the control cells (Adbetagal). Pretreatment with 10 microM of SB203580 suppressed TNF-alpha-induced COX-2 expression, thereby suggesting that p38 MAPK might be involved in COX-2 expression in A549 cells. The phosphorylation of p38 MAPK was increased significantly after 5 minutes of treatment with TNF-alpha, reaching a maximum level at 10 min which persisted for up to 60 min. However, p38MAPK phosphorylation was markedly suppressed in the Ref-1-overexpressed A549 cells. Taken together, our results appear to indicate that Ref-1 negatively regulates COX-2 expression in response to cytokine stimulation via the inhibition of p38 MAPK phosphorylation. In the lung cancer cell lines, Ref-1 may be involved as an important negative regulator of inflammatory gene expression.

Celecoxib enhances the inhibitory effect of cisplatin on Tca8113 cells in human tongue squamous cell carcinoma in vivo and in vitro

BACKGROUND

Overexpression of cyclooxygenase-2 (COX-2) is associated with carcinogenesis, invasiveness, and metastasis of malignant tumors. Inhibition of COX-2 is one hot topic of research in prevention and treatment of malignant tumors. Because of the selective and specific inhibition on the activity of COX-2, the roles of celecoxib in prevention and treatment of tumors have attracted broad attention in recent years. In this study, we investigated the inhibitory effect of celecoxib combined with cisplatin on the proliferation of human tongue squamous cell carcinoma cell line Tca8113 in vivo and in vitro.

METHODS

Human tongue squamous cell carcinoma tumor cells Tca8113 and a mouse model with Tca8113 cells were used to study the growth inhibition of cisplatin enhanced by celecoxib. Drug treatment of Tca8113 in vitro and mice bearing xenografts in vivo were used. The level of COX-2 expression was detected by Western blotting. Sensitivity of cells to drug treatment was analyzed by MTT assay.

RESULTS

Treatment of Tca8113 cells with cisplatin (CDDP) had less effect on the expression of COX-2, whereas the COX-2 expression was significantly down-regulated after treatment with celecoxib alone or in combination with CDDP for 24 h. In addition, the combination of celecoxib with CDDP was also able to inhibit the Tca8113 line heterotransplanted in Balb/c nude mice.

CONCLUSIONS

Those findings indicate that a low dose of celecoxib could augment CDDP-induced growth inhibition of Tca8113 cells and its xenograft in Balb/c nude mice.

Cigarette smoke and increased COX-2 and survivin levels in exhaled breath condensate of lung cancer patients: how hot is the link?

One of the most current intriguing hypotheses on lung cancerogenesis envisages a role for inflammation as a possible trigger of both epithelial-mesenchymal transition and cancer development. Cigarette smoke has been suggested to be the main factor underlying the inflammation of the airways described in lung cancer patients. Cycloxygenase and survivin, a COX-2 dependent factor of apoptosis resistance, seem to play a key role in this regard.

PURPOSE

The aim of this study was to study COX-2 and survivin in the airways of lung cancer patients and in those of a group of smokers in a view to increasing our understanding of the link between smoking, airway inflammation and lung cancer.

PATIENTS AND METHODS

70 NSCLC patients (28 smokers, 26 ex-smokers and 16 non-smokers) and 30 healthy subjects (20 smokers and 10 non-smokers) were enrolled in the study. Both COX-2 and survivin concentrations were measured in the exhaled breath condensates of all the subjects under study using EIA kits.

RESULTS

Higher levels of exhaled survivin and COX-2 were found in NSCLC patients compared to healthy smokers and non-smokers. These levels were observed to be significantly elevated in smokers (patients with lung cancer and healthy) and ex-smokers compared to non-smokers and exhibited a positive correlation with the number of cigarettes smoked expressed as pack/year. A correlation was also found between exhaled COX-2 and survivin and the progression of cancer.

CONCLUSIONS

We support the hypothesis that cigarette smoke be strongly connected to the inflammation of the airways observed in lung cancer patients. On the basis of the results obtained the use of exhaled breath condensate COX-2 and survivin levels could be suggested as two potential markers within an early non-invasive screening of populations of smokers at risk of lung cancer.

Biological activity of celecoxib in the bronchial epithelium of current and former smokers

Non-small cell lung cancer is the primary cause of cancer-related death in Western countries. One important approach taken to address this problem is the development of effective chemoprevention strategies. In this study, we examined whether the cyclooxygenase-2 inhibitor celecoxib, as evidenced by decreased cell proliferation, is biologically active in the bronchial epithelium of current and former smokers. Current or former smokers with at least a 20 pack-year (pack-year = number of packs of cigarettes per day times number of years smoked) smoking history were randomized into one of four treatment arms (3-month intervals of celecoxib then placebo, celecoxib then celecoxib, placebo then celecoxib, or placebo then placebo) and underwent bronchoscopies with biopsies at baseline, 3 months, and 6 months. The 204 patients were primarily (79.4%) current smokers: 81 received either low-dose celecoxib or placebo and 123 received either high-dose celecoxib or placebo. Celecoxib was originally administered orally at 200 mg twice daily and the protocol subsequently increased the dose to 400 mg twice daily. The primary end point was change in Ki-67 labeling (from baseline to 3 months) in bronchial epithelium. No cardiac toxicities were observed in the participants. Although the effect of low-dose treatment was not significant, high-dose celecoxib decreased Ki-67 labeling by 3.85% in former smokers and by 1.10% in current smokers-a significantly greater reduction (P = 0.02) than that seen with placebo after adjusting for metaplasia and smoking status. A 3- to 6-month celecoxib regimen proved safe to administer. Celecoxib (400 mg twice daily) was biologically active in the bronchial epithelium of current and former smokers; additional studies on the efficacy of celecoxib in non-small cell lung cancer chemoprevention may be warranted.

Reactive Oxygen Species And Lung Tumorigenesis By Mutant K-ras: A Working Hypothesis

Wild-type K-ras is tumor suppressive in mouse lung, but mutant K-ras is actively oncogenic. Thus, the mutant protein must acquire new, dominant protumorigenic properties. Generation of reactive oxygen species could be one such property. The authors demonstrate increased peroxides in lung epithelial cells (E10)-transfected with mutant hK-ras(va112). An associated increase in DNA damage (comet assay) correlates with increased cyclooxygenase-2 protein. This DNA damage is completely abrogated by a specific cyclooxygenase-2 inhibitor (SC58125) or by a cell-permeable modified catalase. Literature is reviewed regarding generation of reactive oxygen and cyclooxygenase-2 induction by ras, cyclooxygenase-2 release of DNA-damaging reactive oxygen, and involvement of cyclooxygenase-2 and reactive oxygen in lung cancer

Cyclooxygenase-2 expression in non-Hodgkin's lymphomas

Cyclooxygenase 2 (Cox-2) is a key enzyme in prostaglandin synthesis and it has an important role in the pathogenesis of various malignancies. Cox-2 has been studied in solid tumors; however, studies about the role of Cox-2 in non-Hodgkin's lymphomas (NHL) are limited. The aim of this study is to determine the importance of Cox-2 expression in lymphomas. To this end, Cox-2 expression was determined in 177 cases with NHL. In histological terms, 60 cases (33%) had low grade and 117 (67%) had aggressive lymphoma. Ninety-nine cases were found to be positive for Cox-2 (56%); Cox-2 score was between 50 and 100, 101 and 200 and over 200 in 38, 46 and 15 cases, respectively. There was an important association between aggressive histology and Cox-2 expression: Cox-2 was negative in about half of the cases with indolent morphology, while two thirds of the Cox-2 positive cases had aggressive histology (p = 0.036). There was no significant association between Cox-2 expression and clinical-laboratory parameters. Although the overall survival times were longer in cases with lower or no Cox-2 expression as compared with higher Cox-2 expression, the difference was not significant. In conclusion Cox-2 expression is seen about 60% of the cases with NHL and is associated with aggressive morphology.

Association of nonsteroidal anti-inflammatory drugs with lung cancer: results from a large cohort study

BACKGROUND

Lung cancer is the most common cause of cancer-related mortality. Smoking cessation is crucial to decrease risk, but additional prevention modalities are needed. The use of nonsteroidal anti-inflammatory drugs (NSAID) may be promising.

METHODS

The study was a prospective cohort of 77,125 men and women, ages 50 to 76 years, from Washington state recruited in 2000 to 2002 (the VITamin And Lifestyle study). Lung cancer cases were identified through the Seattle-Puget Sound Surveillance, Epidemiology and End Results cancer registry during 5 years of follow-up. Hazard ratios (HR) associated with 10-year average use of total NSAIDs (excluding low-dose aspirin) and specific categories of NSAIDs were calculated for total incident lung cancer and specific morphologies.

RESULTS

A total of 665 lung cancer cases were identified. After adjusting for smoking, age, gender, and acetaminophen use, there was a borderline-significant inverse trend with total NSAID use [>4.2 d/wk for >10 years versus none: HR, 0.82; 95% confidence interval (95% CI), 0.64-1.04; P for trend = 0.05]. The association was strongest for adenocarcinoma (HR, 0.59; 95% CI, 0.37-0.94; P for trend = 0.01) and seemed to be limited to men (HR, 0.66; 95% CI, 0.47-0.92; P for trend = 0.01) and to long-term (> or =10 years) former smokers (HR, 0.65; 95% CI, 0.44-0.96; P for trend = 0.04). There were no appreciable differences by NSAID type.

CONCLUSIONS

Total NSAID use was associated with a small reduced risk of lung cancer, which was strongest for adenocarcinoma, men, and long-term former smokers. These findings are supported by known lung carcinogenesis mechanisms and suggest that NSAIDS may be useful for chemoprevention.

Smoking and lung cancer: the role of inflammation

Worldwide over 1 million people die due to lung cancer each year. It is estimated that cigarette smoking explains almost 90% of lung cancer risk in men and 70 to 80% in women. Clinically evident lung cancers have multiple genetic and epigenetic abnormalities. These abnormalities may result in activation of oncogenes and inactivation of tumor-suppressor genes. Chronic inflammation, which is known to promote cancer, may result both from smoking and from genetic abnormalities. These mediators in turn may be responsible for increased macrophage recruitment, delayed neutrophil clearance, and increase in reactive oxygen species (ROS). Thus, the pulmonary environment presents a unique milieu in which lung carcinogenesis proceeds in complicity with the host cellular network. The pulmonary diseases that are associated with the greatest risk for lung cancer are characterized by abundant and deregulated inflammation. Pulmonary disorders such as chronic obstructive pulmonary disease (COPD)/emphysema are characterized by profound abnormalities in inflammatory and fibrotic pathways. The cytokines and growth factors aberrantly produced in COPD and the developing tumor microenvironment have been found to have deleterious properties that simultaneously pave the way for both epithelial-mesenchymal transition (EMT) and destruction of specific host cell-mediated immune responses. Full definition of these pathways will afford the opportunity to intervene in specific inflammatory events mediating lung tumorigenesis and resistance to therapy.

Role of p53 in the induction of cyclooxygenase-2 by cisplatin or paclitaxel in non-small cell lung cancer cell lines

Non-small cell lung Cancer (NSCLC) is extremely resistant to chemotherapeutic agents, such as cisplatin. High expression of the inflammatory enzyme cyclooxygenase-2 (COX-2) has been shown to inhibit chemotherapy-induced apoptosis, but little is known about COX-2 regulation upon drug treatment. Recent data indicate the tumor suppressor protein p53 as an important regulator of COX-2. Therefore, TP53 status could change tumor sensitivity to chemotherapy through induction of the anti-apoptotic protein COX-2. The main objective of this work was to analyze the effect of chemotherapy on the expression of COX-2, according to TP53 status. We report herein that lung cancer cell lines expressing wild-type p53, when exposed to cisplatin treatment, induced COX-2 (mRNA and protein), with concurrent synthesis of prostaglandins (PGE(2)). In contrast, COX-2 expression was not changed after cisplatin treatment of cells containing an inactive form of p53. Further, after silencing of wild-type p53 expressed in A549 cells by RNA interference, cisplatin was no longer able to induce COX-2 expression. Therefore, we suggest that induction of COX-2 by cisplatin in NSCLC cell lines is dependent on p53. For paclitaxel treatment, an increase in COX-2 mRNA expression was observed in H460 and A549 (wild-type p53 cell lines). Moreover, paclitaxel treatment increased COX-2 expression in ACC-LC-319 cell lines (p53 null), showing a p53-independent effect. These data may have therapeutic implications in the selection of patients and strategy for future COX-2 inhibition trials.

The role of celecoxib in Rad51 expression and cell survival affected by gefitinib in human non-small cell lung cancer cells

Celecoxib (Celebrex) is a cyclooxygenase-2 (COX-2) selective inhibitor and gefitinib (Iressa(R), ZD1839) is a selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor for human non-small cell lung cancer (NSCLC). The addition of celecoxib to gefitinib to prolong the survival of patients with NSCLC still remains controversial and needs to be investigated. The Rad51 protein is essential for homologous recombination repair, and is overexpressed in chemo- or radioresistant carcinomas. In this study, we characterize the role of celecoxib in the cytotoxicity, ERK1/2 activation and Rad51 expression affected by gefitinib in NSCLC cells. We show that celecoxib can enhance the cytotoxicity induced by gefitinib in NSCLC cells. Treatment with celecoxib alone has no effect on the ERK1/2 activation, Rad51 mRNA and protein levels, however, combined treatment with gefitinib results in a significant reduction of phospho-ERK1/2 and Rad51 protein levels, and triggers the degradation of Rad51 via a 26S proteasome-dependent pathway. Expression of constitutively active MKK1/2 vectors (MKK1/2-CA) significantly rescues the decreased ERK1/2 activity, and restores Rad51 protein levels and cell survival under co-treatment with gefitinib and celecoxib. Furthermore, blocking ERK1/2 activation by U0126 (MKK1/2 inhibitor) and knocking down Rad51 expression by transfection with small interfering RNA of Rad51 can enhance the cytotoxicity of celecoxib.

A phase II study of carboplatin and paclitacel with meloxicam

BACKGROUND

Cyclooxygenase (COX-2) overexpression is seen in many malignancies including lung cancer. Recent pre-clinical studies have shown that selective COX-2 inhibitors have demonstrated promising results when used with chemotherapy. Based on these observations, we assessed the efficacy and tolerability of the combination chemotherapy consisting of carboplatin and paclitaxel with meloxicam, a selective COX-2 inhibitor.

METHODS

Forty-four patients with stage IIIB or IV non-small cell lung cancer (NSCLC), Eastern Cooperative Oncology Group performance status (PS) 0 or 1, who had adequate organ function, were eligible. Patients received paclitaxel 70 mg/m(2) weekly for 3 of 4 weeks with carbopltin (AUC 6) on day 1, as well as daily meloxicam (10 mg/day). The response rate was the primary endpoint. Secondary endpoints were overall survival, toxicity profile and quality of life (using European Organization for Research and Treatment of Cancer (EORTC) QLQ-C30 and LC13).

RESULTS

From March 2005 to September 2006, 44 patients were evaluated in this study. Gender M/F, 31/13; median age, 64 years (range, 34-75); stage IIIB/IV, 11/33; PS0/1, 22/22; histology Ad/Sq/Other, 29/6/9. Partial response was observed in 19 patients (43%) with stable disease, and there was no complete response, for an overall response rate of 43% (95% confidence interval, 28.5-57.8%). Ten patients (23%) had grade (G) 3 and three (7%) had G4 neutropenia. Three patients (7%) had G3 thrombocytopenia. As for non-hematological toxicities, one case of G4 toxicity (perforation of jejunum) was observed, but other toxicities were mild (one muscle pain, two liver dysfunction, one fatigue and one nausea G3). Grade 2 peripheral neuropathy was observed in only one patient. Using the EORTC QLQ questionnaire, the global health status did not change significantly during this therapy (before and 4 and 8 weeks later). Median follow-up was 13.6 months (range, 1.8-31.3 months). By the time of the final analysis (October 2007), 26 of the initial 44 patients had died. The 1-year survival rate was 64% and median survival time was 15.9 months.

CONCLUSIONS

Meloxicam in combination with carboplatin and weekly paclitaxel chemotherapy showed promising activity with encouraging survival. This therapy is relatively well tolerated in advanced NSCLC.

COX-2/EGFR expression and survival among women with adenocarcinoma of the lung

Previous studies suggest that cyclooxygenase-2 (COX-2) expression may predict survival among patients with non-small cell lung cancer. COX-2 may interact with epidermal growth factor receptor (EGFR), suggesting that combined COX-2/EGFR expression may provide predictive value. The extent to which their independent or combined expression is associated with prognosis in women with adenocarcinoma of the lung is unknown. In the present study, we examined relationships between COX-2 expression (n = 238), EGFR expression (n = 158) and dual COX-2/EGFR expression (n = 157) and survival among women with adenocarcinoma of the lung. Overall survival was estimated by constructing Cox proportional hazards models adjusting for other significant variables and stratifying by stage at diagnosis and race. Clinical or demographic parameters were not associated with either COX-2 or EGFR expression. Patients with COX-2-positive tumors tended to have poorer prognosis than did patients with COX-2-negative tumors [hazard ratio (HR) 1.67, 95% confidence interval (CI) 1.01-2.78]. African-Americans with COX-2-positive tumors had a statistically non-significant higher risk of death than African-Americans with COX-2-negative tumors (HR 5.58, 95% CI 0.64-48.37). No association between COX-2 expression and survival was observed among Caucasians (HR 1.29, 95% CI 0.72-2.30). EGFR expression was associated with a 44% reduction in the risk of death (HR 0.56, 95% CI 0.32-0.98). COX-2-/EGFR+ tumor expression, but not COX-2+/EGFR+ tumor expression, was associated with survival when compared with other combined expression results. In conclusion, COX-2 and EGFR expression, but not combined COX-2+/EGFR+ expression, independently predict survival of women with adenocarcinoma of the lung.

Inflammation in lung carcinogenesis: new targets for lung cancer chemoprevention and treatment

Lung carcinogenesis is a complex process involving the acquisition of genetic mutations that confer cancer development and the malignant phenotype, and is critically linked to apoptosis resistance, unregulated proliferation, invasion, metastasis, and angiogenesis. Epithelial mesenchymal transition (EMT) in cancer is an unregulated process in a host environment with deregulated inflammatory response that impairs cell-mediated immunity and permits cancer progression. Given the immunosuppressive tumor environment, strategies to reverse these events by stimulating host immune responses are an important area of investigation. Cyclooxygenase 2 (COX-2) and its downstream signaling pathways are potential targets for lung cancer chemoprevention and therapy. Clinical trials are underway to evaluate COX-2 inhibitors as adjuvants to chemotherapy in patients with lung cancer and to determine efficacy in prevention of bronchogenic carcinoma. The understanding of molecular mechanisms involved in inflammation and lung carcinogenesis provide insight for new drug development that target reversible, non-mutational events in the chemoprevention and treatment of lung cancer.

Epigenetic alteration of Wnt pathway antagonists in progressive glandular neoplasia of the lung

BACKGROUND

Atypical adenomatous hyperplasia (AAH) is now recognized as a precursor lesion from which lung adenocarcinomas arise and thus represents an ideal target for studying the early genetic and epigenetic alterations associated with lung tumorigenesis such as alterations of the Wnt pathway.

METHODS

We assessed the level of Wnt signaling activity in lung cancer cell lines by determining the level of active beta-catenin and determined the level of expression of Wnt antagonists APC, DKK1, DKK3, LKB1, SFRP1, 2, 4, 5, WIF1 and RUNX3 using reverse transcription-polymerase chain reaction. Using multiplex nested methylation-specific polymerase chain reaction, we analyzed promoter region methylation of these genes in resected lung tissue in the histopathologic sequence of glandular neoplasia (normal lung parenchyma, low-grade and high-grade AAH, adenocarcinoma).

RESULTS

The majority of non-small cell lung cancer cell lines (11 of 16, 69%) have evidence of active Wnt signaling and silencing of Wnt antagonists correlated with promoter hypermethylation. Promoter region methylation of Wnt antagonists was common in primary lung adenocarcinoma and there was a significant increase in the frequency of methylation for Wnt antagonist genes and the number of genes methylated with each stage of tumorigenesis (test for rend P <or= 0.01). Additionally, odds ratios for promoter hypermethylation of individual or multiple Wnt antagonist genes and adenocarcinomas were statistically significantly elevated and ranged between 3.64 and 48.17.

CONCLUSION

These results show that gene silencing of Wnt antagonists by promoter hypermethylation occurs during the earliest stages of glandular neoplasia of the lung and accumulates with progression toward malignancy.

Down-regulation of tyrosinase expression by acetylsalicylic acid in murine B16 melanoma

Acetylsalicylic acid (aspirin; ASA) is widely used as an analgesic/antipyretic drug. ASA exhibits a wide range of biological effects, including preventative effects against heart attack, stroke, and the development of some types of cancer. However, the effects of ASA on melanogenesis are not well known. Therefore, we investigated the effect of ASA on melanin production using B16 murine melanoma cells and demonstrated a new biological effect of ASA. In the presence of alpha-melanocyte stimulating hormone (alpha-MSH), B16 melanoma cells are stimulated to enhance melanin synthesis. ASA (2 mM) inhibited alpha-MSH-enhanced melanin synthesis in melanoma more strongly than other well-known anti-melanogenic agents such as arbutin (2 mM) and kojic acid (200 microM). Interestingly, ASA did not inhibit the catalytic activity of mushroom tyrosinase (concentration range 0.5-4.0 mM). To clarify the target of ASA action in melanogenesis, we performed Western blotting for tyrosinase, which is a key melanogenic enzyme. ASA inhibited tyrosinase expression in a dose-dependent manner. Therefore, the depigmenting effect of ASA might be due to inhibition of tyrosinase expression or enhancement of tyrosinase degradation. This study suggests that ASA is a candidate anti-melanogenic agent and it might be effective in hyperpigmentation disorders.

Regular adult aspirin use decreases the risk of non-small cell lung cancer among women

BACKGROUND

Prior studies indicate that use of aspirin or other nonsteroidal anti-inflammatory drugs (NSAID) is associated with a decreased risk of non-small cell lung cancer (NSCLC); however, results have been contradictory in part because of variation in study design. Few studies have examined the use of aspirin or other NSAIDs on risk of NSCLC in women.

METHODS

Through a case-control study of African American and Caucasian women with and without NSCLC, we examined the relationship between use of aspirin, NSAIDs, and acetaminophen and risk of NSCLC. Risk was estimated by calculating odds ratios and 95% confidence intervals for ever/never use, duration of use, and duration of use category (never, 1-5 years, >5 years) after adjusting for major risk factors for lung cancer. Risk estimates were stratified by race, age, smoking history, and body mass index.

RESULTS

Every use of adult-strength aspirin was associated with a significant reduction in risk of NSCLC (odds ratio, 0.66; 95% confidence interval, 0.46-0.94). Additionally, there was a significant trend toward a reduced risk of NSCLC in adult-strength aspirin users with increasing duration of use (P(trend) = 0.02). In stratified analyses, aspirin use was associated with a significantly reduced risk of lung cancer among Caucasians and 55- to 64-year-olds. Baby aspirin and NSAID use was associated with a significant reduction in risk of NSCLC only among 65- to 74-year-olds.

CONCLUSION

Our results suggest that long-term use of adult-strength aspirin may reduce the risk of NSCLC in women.

Use of NSAIDs, smoking and lung cancer risk

We investigated the risk of lung cancer in relation to non-steroidal anti-inflammatory drugs (NSAIDs) among 573 cases and 857 sex- and age-matched controls for whom we had information on use of NSAIDs, from a prescription database covering all pharmacies in Denmark since 1995, and self-reported NSAID use, smoking habits and other potential confounders. Associations were expressed as odds ratios, assessed by logistic regression in unmatched analyses. After controlling for smoking habits, length of education and concomitant use of acetaminophen, we found a slightly decreased relative risk of 0.86 (95% confidence intervals, 0.65–1.14) for lung cancer associated with any use of NSAIDs. The risk decreased significantly (P=0.02) with increasing numbers of dispensed prescriptions per year during the 1–3 years before the index date with a relative risk of 0.49 (0.28–0.84) among those with four or more prescriptions per year during this period. Our findings suggest that regular use of NSAIDs is associated with a slightly or moderately reduced risk for lung cancer.

Polymorphisms in genes involved in the inflammatory response and interaction with NSAID use or smoking in relation to lung cancer risk in a prospective study

Lung cancer risk was investigated in relation to single nucleotide polymorphisms in genes involved in the inflammatory response. The aim was to see if polymorphisms modifying the inflammatory response are associated with risk of lung cancer and if there were interactions between the same polymorphism and factors, which modify an inflammatory response, such as smoking status, duration, and intensity, and use of NSAID. The functional SNPs IL-1B T-31C, IL6 G-174C, IL8 T-251A, IL10 C-592T, COX2 C8473T, COX2 A-1195G and PPARgamma2 Pro(12)Ala were included. A case-cohort study including 428 lung cancer cases and a sub-cohort of 800 persons was nested within a population-based prospective study of 57,053 individuals. Variant allele carriers of IL-1B T-31C were at increased risk of lung cancer (IRR=1.51, 95% CI=1.08-2.12). There was interaction between the polymorphism COX-2 T8473C and smoking status. Thus, non-smoking variant allele carriers were at 5.75-fold (95% CI=1.25-26.43) higher risk of lung cancer than for homozygous wild type allele carriers. Lung cancer risk was similar for all genotype carriers among past and current smokers. There were, however, very few non-smoking lung cancer cases. There was interaction between IL-1B T-31C, COX-2 A-1195G and PPARgamma2 Pro(12)Ala and NSAID use in relation to lung cancer risk. For the two latter, NSAID use was only associated with a lower cancer risk among homozygous wild type allele carriers. p for interaction was 3 x 10(-6) for COX-2 A-1195G and 9 x 10(-5) for PPARgamma2 Pro(12)Ala. The results suggest that NSAID use may modify risk of lung cancer differently depending on the genotype.

Inflammation and lung carcinogenesis: applying findings in prevention and treatment

Lung carcinogenesis is a complex process requiring the acquisition of genetic mutations that confer the malignant phenotype as well as epigenetic alterations that may be manipulated in the course of therapy. Inflammatory signals in the lung cancer microenvironment can promote apoptosis resistance, proliferation, invasion, metastasis, and secretion of proangiogenic and immunosuppressive factors. Here, we discuss several prototypical inflammatory mediators controlling the malignant phenotype in lung cancer. Investigation into the detailed molecular mechanisms underlying the tumor-promoting effects of inflammation in lung cancer has revealed novel potential drug targets. Cytokines, growth factors and small-molecule inflammatory mediators released in the developing tumor microenvironment pave the way for epithelial-mesenchymal transition, the shift from a polarized, epithelial phenotype to a highly motile mesenchymal phenotype that becomes dysregulated during tumor invasion. Inflammatory mediators within the tumor microenvironment are derived from neoplastic cells as well as stromal and inflammatory cells; thus, lung cancer develops in a host environment in which the deregulated inflammatory response promotes tumor progression. Inflammation-related metabolic and catabolic enzymes (prostaglandin E(2) synthase, prostaglandin I(2) synthase and 15-hydroxyprostaglandin dehydrogenase), cell-surface receptors (E-type prostaglandin receptors) and transcription factors (ZEB1, SNAIL, PPARs, STATs and NF-kappaB) are differentially expressed in lung cancer cells compared with normal lung epithelial cells and, thus, may contribute to tumor initiation and progression. These newly discovered molecular mechanisms in the pathogenesis of lung cancer provide novel opportunities for targeted therapy and prevention in lung cancer.

Aspirin Enhances Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand-Mediated Apoptosis in Hormone-Refractory Prostate Cancer Cells through Survivin Down-Regulation

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising cancer therapeutic agent because of its tumor selectivity. TRAIL is known to induce apoptosis in cancer cells but spare most normal cells. In this study, we examined whether acetylsalicylic acid (ASA), so-called aspirin, enhances TRAIL-induced apoptosis in androgen-dependent LNCaP and androgen-independent LNCaP-derived prostate cancer cells. To evaluate the cell death effects of TRAIL in combination with ASA on tumor cells, we performed DNA fragmentation assay and immunoblot analysis for poly(ADP-ribose) polymerase-1, caspases, and anti-apoptotic proteins. We observed that ASA promoted TRAIL-induced apoptotic death in both LNCaP and its derived cells (C4, C4-2, and C4-2B). These enhancements of TRAIL's effect were related to the decrease in survivin protein expression by pretreatment with ASA. We also confirmed that knockdown in survivin expression by transfecting survivin small interfering RNA increased TRAIL-induced apoptosis. To study the mechanism of survivin down-regulation, we determined the levels of mRNA and the activities of survivin promoter in the ASA-treated and untreated cells. Reduction of the intracellular levels of survivin protein was due to a decrease in transcriptional activity. Data from electrophoretic mobility shift assay and chromatin immunoprecipitation analyses revealed that ASA inhibited the transcription factor E2F-1 binding activity to the survivin promoter region, which is known to regulate survivin gene transcription. Taken together, our studies suggested that ASA-promoted TRAIL cytotoxicity is mediated by down-regulating survivin, and the down-regulation of survivin is due to inhibition of E2F-1 binding activity to the survivin promoter region.

Ciglitazone mediates COX-2 dependent suppression of PGE2 in human non-small cell lung cancer cells

BACKGROUND

Cyclooxygenase-2 (COX-2) over-expression and subsequent prostaglandin E2 (PGE2) production are frequently associated with human non-small-cell lung cancer (NSCLC) and are involved in tumor proliferation, invasion, angiogenesis, and resistance to apoptosis. Here, we report that ciglitazone downregulates PGE2 in NSCLC cells.

METHODS

PGE2 ELISA assay and COX-2 ELISA assay were performed for measuring PGE2 and COX-2, respectively, in NSCLC. The mRNA level of COX-2 was measured by semi-quantitative RT-PCR. The transient transfection experiments were performed to measure COX-2 and peroxisome proliferator-response element (PPRE) promoter activity in NSCLC. Western blots were unitized to measure PGE synthase (PGES) and 15-hydroxyprostaglandin dehydrogenase (15-PGDH) protein expression.

RESULTS

COX-2 ELISA assays suggested that ciglitazone-dependent inhibition of PGE2 occurs through the suppression of COX-2. Ciglitazone treatment suppressed COX-2 mRNA expression and COX-2 promoter activity while upregulating PPRE promoter activity. Ciglitazone did not modify the expression of enzymes downstream of COX-2 including PGES and 15-PGDH. Utilization of a dominant-negative PPARgamma showed that the suppression of COX-2 and PGE2 by ciglitazone is mediated via non-PPAR pathways.

CONCLUSION

Taken together, our findings suggest that ciglitazone is a negative modulator of COX-2/PGE2 in NSCLC.

Characterization of the Effects of Cyclooxygenase-2 Inhibition in the Regulation of Apoptosis in Human Small and Non–Small Cell Lung Cancer Cell Lines

BACKGROUND

Cyclooxygenase-2 enzyme (COX-2) is overexpressed in human non-small cell lung cancer (NSCLC) but is not expressed in small cell lung cancer. Selective COX-2 inhibitors have been shown to induce apoptosis in NSCLC cells, an effect which is associated with the regulation of intracellular MAP kinase (MAPK) signal pathways. Our aims were to characterize the effects of COX-2 inhibition by rofecoxib on apoptosis in human NSCLC and small cell lung cancer cell lines.

METHODS

The human NSCLC cell line NCI-H2126 and small cell lung cancer cell line DMS-79 were used. Constitutive COX-2 protein levels were first determined by Western blot test. Levels of apoptosis were evaluated by using propidium iodide staining on FACScan analysis after incubation of NCI-H2126 and DMS-79 with p38 MAPK inhibitor SB202190 (25 ?microM), NF-kappaB inhibitor SN50 (75 microg/mL), and rofecoxib at 100 and 250 microM. All statistical analysis was performed by analysis of variance.

RESULTS

Western blot test confirmed the presence of COX-2 enzyme in NCI-H2126 and absence in DMS-79. Interestingly, rofecoxib treatment demonstrated a dose-dependent increase in apoptosis in both cell lines. Given this finding, the effect of rofecoxib on NF-kappaB and p38 MAPK pathways was also examined. Apoptosis in both cell lines was unaltered by SN50, either alone or in combination with rofecoxib. A similar phenomenon was observed in NCI-H2126 cells treated with SB202190, either alone or in combination with rofecoxib. In contrast, p38 MAPK inhibition greatly upregulated DMS-79 apoptosis in a manner that was unaltered by the addition of rofecoxib.

CONCLUSIONS

Rofecoxib led to a dose-dependent increase in apoptosis in both tumor cell lines. This effect occurred independently of COX-2, NF-kappaB, and p38 MAPK pathways in DMS-79 cells. As such, rofecoxib must act on alternative pathways to regulate apoptosis in human small cell lung cancer cells.

Induction of lung lesions in Wistar rats by 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and its inhibition by aspirin and phenethyl isothiocyanate

Background

The development of effective chemopreventive agents against cigarette smoke-induced lung cancer could be greatly facilitated by suitable laboratory animal models, such as animals treated with the tobacco-specific lung carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). In the current study, we established a novel lung cancer model in Wistar rats treated with NNK. Using this model, we assessed the effects of two chemopreventive agents, aspirin and phenethyl isothiocyanate (PEITC), on tumor progression.

Methods

First, rats were treated with a single-dose of NNK by intratracheal instillation; control rats received iodized oil. The animals were then sacrificed on the indicated day after drug administration and examined for tumors in the target organs. PCNA, p63 and COX-2 expression were analyzed in the preneoplastic lung lesions. Second, rats were treated with a single-dose of NNK (25 mg/kg body weight) in the absence or presence of aspirin and/or PEITC in the daily diet. The control group received only the vehicle in the regular diet. The animals were sacrificed on day 91 after bronchial instillation of NNK. Lungs were collected and processed for histopathological and immunohistochemical assays.

Results

NNK induced preneoplastic lesions in lungs, including 33.3% alveolar hyperplasia and 55.6% alveolar atypical dysplasia. COX-2 expression increased similarly in alveolar hyperplasia and alveolar atypical dysplasia, while PCNA expression increased more significantly in the latter than the former. No p63 expression was detected in the preneoplastic lesions. In the second study, the incidences of alveolar atypical dysplasia were reduced to 10%, 10% and 0%, respectively, in the aspirin, PEITC and aspirin and PEITC groups, compared with 62.5% in the carcinogen-treated control group. COX-2 expression decreased after dietary aspirin or aspirin and PEITC treatment. PCNA expression was significantly reduced in the aspirin and PEITC group.

Conclusion

(1) A single dose of 25 mg/kg body weight NNK by intratracheal instillation is sufficient to induce preneoplastic lesions in Wistar rat lungs. (2) COX-2 takes part in NNK-induced tumorigenesis but is not involved in proliferation. (3) Aspirin and PEITC have protective effects in the early stages of tumor progression initiated by NNK.

Key signaling pathways and targets in lung cancer therapy

Despite the use of chemotherapy, radiation therapy, and surgery, the overall outcome for lung cancer continues to be disappointing. In order to make a difference in the treatment of lung cancer, novel therapeutics need to be developed. The molecular mechanisms of carcinogenesis in lung cancer are complex and involve multiple oncogenes, tumor suppressor genes, receptor tyrosine kinases, cytoplasmic enzymes, and tumor interstitial elements, among other cellular proteins. In this review, the authors discuss key signaling pathways and molecular targets in the treatment of lung cancer. Through understanding molecular targets and the utilization of specific inhibitors, hopefully, a dramatic impact will be made in the biology and therapy of lung cancer.

Significance of cyclooxygenase-2 in prognosis, targeted therapy and chemoprevention of NSCLC

Evaluation of: Tsubochi H, Nobuyuki S, Hiyama M et al.: Combined analysis of cyclooxygenase-2 expression with p53 and Ki-67 in nonsmall cell lung cancer. Ann. Thorac. Surg. 82(4), 1198–1204 (2006).The report by Tsubochi and colleagues adds to the growing evidence indicating that tumor cyclo-oxygenase (Cox)-2 has a multifaceted role in conferring the malignant phenotype of non-small-cell lung cancer (NSCLC), and provides insight into the use of markers to provide prognostic information. Cox-2 has been implicated in apoptosis resistance, angiogenesis, decreased host immunity and enhanced invasion and metastasis, and, thus, has a critical involvement in carcinogenesis. This study, as well as others, has contributed to providing an insight into opportunities for targeted therapies in NSCLC. Cox-2 is one of the novel targets being studied for lung cancer therapy and chemoprevention.

Nonsteroidal anti-inflammatory drugs and risk of lung cancer

Regular aspirin and non-aspirin nonsteroidal anti-inflammatory drug (NSAID) use is associated with a reduced risk of colorectal cancer. The effect of NSAIDs on the risk of other cancers remains unclear. To evaluate whether use of aspirin or other specific NSAIDs protects against lung cancer, we conducted a case-control study nested in a cohort of subjects 40-84 years old in 1995-2004, without a diagnosis of cancer before the study start date, and with at least 2 years of enrollment with a general practitioner providing data to the The Health Improvement Network (THIN) database in the UK. Patients who had a first diagnosis of primary lung cancer during the study period were considered cases. A random sample of 10,000 controls was frequency-matched to the cases for age, sex and calendar year. The index date for exposure definition was 1 year before the date of diagnosis for cases and 1 year before a random date within the study period for controls. Relative risks and 95% confidence intervals were estimated using conditional logistic regression stratified for matching factors. Factors such as smoking, chronic obstructive pulmonary disease, cardiovascular diseases and body mass index were introduced in the model. We identified 4,336 cases with primary incident lung cancer (incidence rate 7.6 per 10,000 person-years). Compared with subjects with no prescription of non-aspirin NSAID prior to the index date, the risk of lung cancer was 0.76 (0.61-0.94) among those who received a prescription the previous year and had a treatment duration of at least 1 year. The corresponding relative risk was 1.15 (0.99-1.34) for aspirin. In conclusion, prescription of non-aspirin NSAIDs for at least 1 year might be associated with a slightly reduced risk of lung cancer. Aspirin was not associated with a risk reduction, perhaps due to residual confounding.

Cross-talks between cyclooxygenase-2 and tumor suppressor protein p53: Balancing life and death during inflammatory stress and carcinogenesis

Overexpression of Cyclooxygenase-2 (COX-2) is observed in most tumor types. Increased COX-2 activity and synthesis of prostaglandins stimulates proliferation, angiogenesis, invasiveness and inhibits apoptosis. Many stress and proinflammatory signals induce COX-2 expression, including oxyradicals or DNA-damaging agents. The latter also induces p53, a transcription factor often inactivated by mutation in cancer. Several studies have identified complex cross-talks between p53 and COX-2, whereby p53 can either up- or down-regulate COX-2, which in turn controls p53 transcriptional activity. However, the molecular basis of these effects are open to debate, in particular since no p53 binding sequences have been identified in COX-2 regulatory regions. In this review, we summarize the molecular mechanisms by which COX-2 contributes to carcinogenesis and discuss the experimental set-up, results and conclusions of studies analyzing cross-talks between p53 and COX-2. We propose 2 scenarios accounting for overexpression of COX-2 in precursor and cancer lesions. In the "inflammatory" scenario, p53, activated by DNA damage induced by oxygen and nitrogen species, recruits NF-kappaB to activate COX-2, resulting in antiapoptotic effects that contribute to cell expansion in inflammatory precursor lesions. In the "constitutive proliferation" scenario, oncogenic stress due to activation of growth signaling cascades may upregulate COX-2 promoter independently of NF-kappaB and p53, synergizing with TP53 mutation to promote cancer progression. These 2 scenarios, although not mutually exclusive, may account for the diversity of the correlations between COX-2 expression and TP53 mutation, which vary according to cancer types and biological contexts, and have implications for the use of COX-2 inhibitors in cancer prevention and therapy.

Tangeretin suppresses IL-1beta-induced cyclooxygenase (COX)-2 expression through inhibition of p38 MAPK, JNK, and AKT activation in human lung carcinoma cells

Tangeretin (5,6,7,8,4'-pentamethoxyflavone) is a polymethoxylated flavonoid concentrated in the peel of citrus fruits. Recent studies have shown that tangeretin exhibits anti-proliferative, anti-invasive, anti-metastatic, and antioxidant activities. However, the anti-inflammatory properties of tangeretin are unclear. In this study, we examine the effects of tangeretin and its structure-related compound, nobiletin, on the expression of cyclooxygenases-2 (COX-2) in human lung epithelial carcinoma cells, A549, and human non-small cell lung carcinoma cells, H1299. Tangeretin exerts a much better inhibitory activity than nobiletin against IL-1beta-induced production of COX-2 in A549 cells, and it effectively represses the constitutively expressed COX-2 in H1299. RT-PCR was used to investigate the transcriptional inhibition of COX-2 by tangeretin. COX-2 mRNA was rapidly induced by IL-1beta in 3h and markedly suppressed by tangeretin. IL-1beta-induced the activation of ERK, p38 MAPK, JNK, and AKT in A549 cells. COX-2 expression in response to IL-1beta was attenuated by pretreatment with SB203580, SP600125, and LY294002, but not with PD98059, suggesting the involvement of p38 MAPK, JNK, and PI3K in this response. Pretreatment of cells with tangeretin inhibited IL-1beta-induced p38 MAPK, JNK, and AKT phosphorylation and the downstream activation of NF-kappaB. These results may reveal that the tangeretin inhibition of IL-1beta-induced COX-2 expression in A549 cells is, at least in part, mediated through suppression of NF-kappaB transcription factor as well as through suppression of the signaling proteins of p38 MAPK, JNK, and PI3K, but not of ERK.

Non-steroidal anti-inflammatory drugs to potentiate chemotherapy effects: from lab to clinic

Most solid tumors express the cyclooxygenase-2 (COX-2) protein, a target of NSAIDs. COX-2 overexpression in tumorsis considered a predictor of more advanced stage disease and of worse prognosis in a number of studies investigating solid malignancies. Therefore, NSAIDs are evaluated as anti-cancer drugs. NSAIDs inhibit proliferation, invasiveness of tumors, and angiogenesis and overcome apoptosis resistance in a COX-2 dependent and independent manner. This review will focus on the rationale behind NSAIDs, including selective COX-2 inhibitors, in combination with conventional chemotherapeutic drugs or novel molecular targeted drugs. Studies investigating anti-cancer effects of NSAIDs on cell lines and xenograft models have shown modulation of the Akt, NF-kappaB, tyrosine kinase and the death receptor-mediated apoptosis pathways. COX-2 expression in tumors is not yet used as biomarker in the clinic. Despite the increased risk on cardiovascular toxicity induced by selective COX-2 inhibitors, several ongoing clinical trials are still investigating the therapeutic benefits of NSAIDs in oncology. The anti-tumor effects in these trials balanced with the side effects data will define the precise role of selective COX-2 inhibitors in the treatment of cancer patients.

Has Cox-2 a prognostic role in non-small-cell lung cancer? A systematic review of the literature with meta-analysis of the survival results

Cyclooxygenase-2 (COX-2) is overexpressed in lung cancer, especially in adenocarcinoma (ADC). Our aim was to determine the prognostic value of COX-2 on survival in patients with lung cancer. Studies evaluating the survival impact of COX-2 in lung cancer, published until December 2005, were selected. Data for estimation of individual hazard ratios (HR) for survival were extracted from the publications and combined in a pooled HR. Among 14 eligible papers, all dealing with non-small-cell lung cancer, 10 provided results for meta-analysis of survival data (evaluable studies). Cyclooxygenase-2 positivity was associated with reduced survival, improved survival or no statistically significant impact in six, one and seven studies, respectively. Combined HR for the 10 evaluable studies (1236 patients) was 1.39 (95% confidence intervals (CI): 0.97-1.99). In stage I lung cancer (six evaluable studies, 554 patients), it was 1.64 (95% CI: 1.21-2.24). No significant impact was shown in ADC. A slight detrimental effect on survival in patients with lung cancer is associated with COX-2 expression, but the statistical significance is not reached. This effect is statistically significant in stage I, suggesting that COX-2 expression could be useful at early stages to distinguish those with a worse prognosis.

Celecoxib decreases Ki-67 proliferative index in active smokers

PURPOSE

This study evaluated the feasibility of cyclooxygenase-2 (COX-2) inhibition for lung cancer chemoprevention. We hypothesized that treatment with oral Celecoxib, a selective COX-2 inhibitor, would favorably alter the biomarkers of lung cancer risk as measured by the Ki-67 proliferative labeling index (Ki-67 LI).

EXPERIMENTAL DESIGN

Twenty active heavy smokers were enrolled into a pilot study and treated with Celecoxib for 6 months. Bronchoscopies with bronchial biopsies were done before and after 6 months of Celecoxib treatment. H&E stain for histologic grading and immunohistochemical examination for Ki-67 LI, COX-2, and survivin were carried out on serially matched biopsy samples to determine responses to treatment.

RESULTS

Treatment with Celecoxib significantly reduced Ki-67 LI in smokers by 35% (P = 0.016), and increased the expression of nuclear survivin by 23% (P = 0.036) without significantly changing that of cytoplasmic survivin.

CONCLUSIONS

Our findings suggest that oral Celecoxib may be capable of modulating the proliferation indices and apoptotic balance in bronchial tissue of active smokers.

Chemoprevention strategies with cyclooxygenase-2 inhibitors for lung cancer

Clinical lung cancer is the ultimate event resulting from a series of genetic and epigenetic alterations in the respiratory epithelium at risk. According to the "field carcinogenesis" theory, these alterations can occur throughout the entire lung. In individuals with a genetic predisposition combined with a sufficient amount of procarcinogenic environmental influences, a few of these sites may eventually progress to malignancies. Recent advances in the understanding of tumor biology have identified new therapeutic targets for lung cancer chemoprevention, among which is cyclooxgygenase (COX)-2. Ample preclinical data suggest that the COX-2/prostaglandin E2 (PGE2) signaling pathway plays a pivotal role in conferring the malignant phenotype. Produced primarily by the action of COX on the free arachidonic acid liberated from membrane phospholipids, overproduction of PGE2, which is predominantly generated by upregulation of COX-2, is associated with a variety of mechanisms known to facilitate tumorigenesis. These mechanisms include abnormal expression of epithelial growth factors, epithelial and microvascular proliferation, resistance to apoptosis, and suppression of antitumor immunity. The lung is one of the major sites of PGE2 production, and previous studies have shown elevated PGE2 levels in bronchoalveolar lavage fluid of patients with bronchogenic carcinoma. In animal models, inhibition of COX-2 and PGE2 synthesis suppresses lung tumorigenesis. These preclinical data suggesting the antineoplastic effect of COX-2 inhibitors provide the basis for several ongoing pilot clinical trials to determine the feasibility of COX-2 inhibition in chemoprevention of bronchogenic carcinoma.

Pretreatment of acetylsalicylic acid promotes tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis by down-regulating BCL-2 gene expression

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has been shown to be selective in the induction of apoptosis in cancer cells with minimal toxicity to normal tissues. However, not all cancers are sensitive to TRAIL-mediated apoptosis. Thus, TRAIL-resistant cancer cells must be sensitized first to become responsive to TRAIL. In this study, we observed that pretreatment by acetylsalicylic acid (ASA) augmented TRAIL-induced apoptotic death in human prostate adenocarcinoma LNCaP and human colorectal carcinoma CX-1 cells. Western blot analysis showed that pretreatment of ASA followed by TRAIL treatment activated caspases (8, 9, and 3) and cleaved poly(ADP-ribose) polymerase, the hallmark feature of apoptosis. Most interestingly, at least 12 h of pretreatment with ASA was prerequisite for promoting TRAIL-induced apoptosis and was related to down-regulation of BCL-2. Biochemical analysis revealed that ASA inhibited NF-kappaB activity, which is known to regulate BCL-2 gene expression, by dephosphorylating IkappaB-alpha and inhibiting IKKbeta activity but not by affecting the HER-2/neu phosphatidylinositol 3-kinase-Akt signal pathway. Overexpression of BCL-2 suppressed the promotive effect of ASA on TRAIL-induced apoptosis and changes in mitochondrial membrane potential. Taken together, our studies suggested that ASA-promoted TRAIL cytotoxicity is mediated through down-regulating BCL-2 and by decreasing mitochondrial membrane potential.

Cyclooxygenase 2 inhibition promotes IFN-gamma-dependent enhancement of antitumor responses

In previous studies, we demonstrated an immune suppressive network in non-small cell lung cancer that is due to overexpression of tumor cyclooxygenase 2 (COX-2). In this study, we assessed the vaccination response to tumor challenge following either pharmacological or genetic inhibition of COX-2 in a murine lung cancer model. Treatment of naive mice with the COX-2 inhibitor, SC-58236, skewed splenocytes toward a type 1 cytokine response, inducing IFN-gamma, IL-12, and IFN-gamma-inducible protein 10, whereas the type 2 cytokines IL-4, IL-5, and IL-10 remained unaltered. Fifty percent of mice receiving SC-58236 and an irradiated tumor cell vaccine completely rejected tumors upon challenge. Those mice that did form tumors following challenge demonstrated a reduced tumor growth. In contrast, all mice either vaccinated with irradiated tumor cells alone or receiving SC-58236 alone showed progressive tumor growth. Studies performed in CD4 and CD8 knockout mice revealed a requirement for the CD4 T lymphocyte subset for the complete rejection of tumors. To determine the role of host COX-2 expression on the vaccination responses, studies were performed in COX-2 gene knockout mice. Compared with control littermates, COX-2(-/-) mice showed a significant tumor growth reduction, whereas heterozygous COX-2(-/+) mice had an intermediate tumor growth reduction following vaccination. In vivo depletion of IFN-gamma abrogated the COX-2 inhibitor-mediated enhancement of the vaccination effect. These findings provide a strong rationale for additional evaluation of the capacity of COX-2 inhibitors to enhance vaccination responses against cancer.

Targeting Cyclooxygenase-2 in Recurrent Non–Small Cell Lung Cancer: A Phase II Trial of Celecoxib and Docetaxel

Cyclooxygenase-2 (COX-2) catalyzes the rate-limiting step in prostaglandin (PG) synthesis and is overexpressed in 70% to 90% of non-small cell lung cancers (NSCLC). Preclinical studies suggest inhibition of COX-2 can enhance the cytotoxic effect of docetaxel. To test this concept clinically, we administered celecoxib (400 mg p.o. twice daily) plus docetaxel (75 mg/m(2) every 3 weeks) to a cohort of patients with recurrent, previously treated NSCLC. Patients first received single agent celecoxib for 5 to 10 days to ascertain the effectiveness of COX-2 inhibition, which was determined by measuring pre- and post-celecoxib levels of urinary 11alpha-hydroxy-9,15-dioxo-2,3,4,5-tetranor-prostane-1,20-dioic acid (PGE-M), the major metabolite of prostaglandin E(2) (PGE(2)). We enrolled 56 patients (35 men, 21 women; median age, 61 years). All patients had received at least one prior chemotherapy regimen. The overall response rate was 11% and median survival was 6 months, similar to that observed with docetaxel alone. Pre-celecoxib urinary PGE-M decreased from a mean level of 27.2 to 12.2 ng/mg Cr after 5 to 10 days of celecoxib (P = 0.001). When grouped by quartile, patients with the greatest proportional decline in urinary PGE-M levels experienced a longer survival compared to those with no change or an increase in PGE-M (14.8 versus 6.3 versus 5.0 months). Our data suggest that combining celecoxib with docetaxel using the doses and schedule employed does not improve survival in unselected patients with recurrent, previously treated NSCLC. However, in light of the apparent survival prolongation in the subset with a marked decline in urinary PGE-M levels, further investigation of strategies designed to decrease PGE(2) synthesis in NSCLC seems warranted.

Curcumin inhibits interferon-α induced NF-κB and COX-2 in human A549 non-small cell lung cancer cells

The A549 cells, non-small cell lung cancer cell line from human, were resistant to interferon (IFN)-alpha treatment. The IFN-alpha-treated A549 cells showed increase in protein expression levels of NF-kappaB and COX-2. IFN-alpha induced NF-kappaB binding activity within 30 min and this increased binding activity was markedly suppressed with inclusion of curcumin. Curcumin also inhibited IFN-alpha-induced COX-2 expression in A549 cells. Within 10 min, IFN-alpha rapidly induced the binding activity of a gamma-(32)P-labeled consensus GAS oligonucleotide probe, which was profoundly reversed by curcumin. Taken together, IFN-alpha-induced activations of NF-kappaB and COX-2 were inhibited by the addition of curcumin in A549 cells.

Inhibition of mammalian target of rapamycin reverses alveolar epithelial neoplasia induced by oncogenic K-ras

The serine/threonine kinase AKT and its downstream mediator mammalian target of rapamycin (mTOR) are activated in lung adenocarcinoma, and clinical trials are under way to test whether inhibition of mTOR is useful in treating lung cancer. Here, we report that mTOR inhibition blocked malignant progression in K-ras(LA1) mice, which undergo somatic activation of the K-ras oncogene and display morphologic changes in alveolar epithelial cells that recapitulate those of precursors of human lung adenocarcinoma. Levels of phospho-S6(Ser236/235), a downstream mediator of mTOR, increased with malignant progression (normal alveolar epithelial cells to adenocarcinoma) in K-ras(LA1) mice and in patients with lung adenocarcinoma. Atypical alveolar hyperplasia, an early neoplastic change, was prominently associated with macrophages and expressed high levels of phospho-S6(Ser236/235). mTOR inhibition in K-ras(LA1) mice by treatment with the rapamycin analogue CCI-779 reduced the size and number of early epithelial neoplastic lesions (atypical alveolar hyperplasia and adenomas) and induced apoptosis of intraepithelial macrophages. LKR-13, a lung adenocarcinoma cell line derived from K-ras(LA1) mice, was resistant to treatment with CCI-779 in vitro. However, LKR-13 cells grown as syngeneic tumors recruited macrophages, and those tumors regressed in response to treatment with CCI-779. Lastly, conditioned medium from primary cultures of alveolar macrophages stimulated the proliferation of LKR-13 cells. These findings provide evidence that the expansion of lung adenocarcinoma precursors induced by oncogenic K-ras requires mTOR-dependent signaling and that host factors derived from macrophages play a critical role in adenocarcinoma progression.

Novel Strategies for the Early Detection and Prevention of Lung Cancer

Lung cancer is the leading cause of cancer death in the United States. Despite evidence of molecular abnormalities in biological specimens, progress in this disease is hampered by the lack of diagnostic markers useful for clinical practice. The majority of patients with lung cancer are still diagnosed at an advanced stage, when prognosis is poor. This article reviews new strategies being studied for the early detection of lung cancer. These strategies involve new methods of imaging (including low-dose computed tomography [CT] scanning), DNA analysis, and proteomic-based techniques. These strategies have not only improved our understanding of lung cancer but show promise in offering better survival to patients with this deadly disease. Of paramount importance in the search for methods of early detection is the need for the identification of the ideal population to screen, a multidisciplinary approach, and validation of promising techniques.