Nuclear factor-kappaB (NF-kappaB) is frequently expressed in lung cancer and preneoplastic lesions

Epithelial NF-kappaB activation promotes urethane-induced lung carcinogenesis

Chronic inflammation is linked to carcinogenesis in several organ systems. In the lungs, NF-kappaB, a central effector of inflammatory responses, is frequently activated in non-small-cell lung cancer, but its role in tumor promotion has not been studied. Several lines of evidence indicate that ethyl carbamate (urethane)-induced lung tumor formation, a prototypical mouse model of multistage lung carcinogenesis, is potentiated by inflammation. We found that mouse strains susceptible to lung tumor formation (FVB, BALB/c) exhibited early NF-kappaB activation and inflammation in the lungs after urethane treatment. However, a resistant strain (C57B6) failed to activate NF-kappaB or induce lung inflammation. In FVB mice, we identified urethane-induced NF-kappaB activation in airway epithelium, as well as type II alveolar epithelial cells and macrophages. Using an inducible transgenic mouse model (FVB strain) to express a dominant inhibitor of NF-kappaB specifically in airway epithelial cells, we found that urethane-induced lung inflammation was blocked and tumor formation was reduced by >50%. Selective NF-kappaB inhibition resulted in increased apoptosis of airway epithelial cells at 2 weeks after urethane treatment in association with a marked reduction of Bcl-2 expression. These studies indicate that NF-kappaB signaling in airway epithelium is integral to tumorigenesis in the urethane model and identify the NF-kappaB pathway as a potential target for chemoprevention of lung cancer.

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.

Inhibition of cell growth and induction of apoptosis via inactivation of NF-kappaB by a sulfurcompound isolated from garlic in human colon cancer cells

Compounds such as S-allylmercaptocysteine, diallyl disulfide, and S-trityl-L-cysteine isolated from garlic have been known to be effective in chemoprevention. Nuclear transcription factor-kappaB (NF-kappaB) has been known to be an implicated factor in apoptotic cell death of several cancer cells. In this study, we investigated whether a sulfurcompound (named thiacremonone) isolated from garlic could modulate NF-kappaB activity and thereby induce apoptotic cell death of colon cancer cells. Treatment with different concentrations (30 - 150 microg/ml) of thiacremonone for various periods (0 - 48 h) inhibited colon cancer cell (SW620 and HCT116) growth followed by induction of apoptosis in a dose-dependent manner. We also found that thiacremonone modulated tumor necrosis factor-alpha (TNF-alpha) and tetradeanoyl phorbol acetate (TPA)-induced NF-kappaB transcriptional and DNA binding activity. Moreover, thiacremonone suppressed NF-kappaB target anti-apoptotic genes (Bcl-2, cIAP1/2, and XIAP) and inflammatory genes (iNOS and COX-2), whereas it induced apoptotic genes (Bax, cleaved caspse-3, and cleaved PARP) expression. These results suggest that a novel sulfurocompound from garlic inhibited colon cancer cell growth through induction of apoptotic cell death by modulating of NF-kappaB.

Combined prognostic value of both RelA and IkappaB-alpha expression in human non-small cell lung cancer

BACKGROUND

We sought to investigate the prognostic significance of nuclear factor (NF)-kappaB activity, especially nuclear RelA and IkappaB-alpha expression patterns, in non-small cell lung cancer (NSCLC).

METHODS

A total of 116 patients with pathologically confirmed stage I to II NSCLC were included. Immunohistochemical analysis and electrophoretic mobility shift assays of NF-kappaB were performed to determine RelA and phosphorylated IkappaB-alpha staining, and DNA binding activity of NF-kappaB in human NSCLC. Downstream genes, including VEGF and IL-8, were also assessed. The prognostic significance of a single expression of RelA, phosphorylated IkappaB-alpha, and b-composite expressions was evaluated by Cox proportional hazard regression models and by Kaplan-Meier survival analyses. Correlation between RelA/IkappaB-alpha expression status and clinicopathological features of NSCLC was also analyzed.

RESULTS

NF-kappaB DNA binding activity, VEGF, and IL-8 showed correlation with nuclear RelA and cytoplasmic pIkappaB-alpha expression. Expression of nuclear RelA/NF-kappaB showed an increase in NSCLC tissue compared with adjacent normal tissue and normal lung tissue. There was a positive correlation between NF-kappaB activation (nuclear translocation of RelA) and tumor clinicopathological features such as tumor grade, including T stages, N stages, and tumor, node, metastasis system stages, smoking status, and age. Positive correlation was observed between nuclear RelA and cytoplasmic pIkappaB-alpha. Both nuclear RelA and cytoplasmic pIkappaB-alpha were associated with poor prognosis by univariate and multivariate analyses.

CONCLUSIONS

Nuclear RelA and cytoplasmic pIkappaB-alpha expression are associated with a poorer prognosis in NSCLC patients. In particular, composite application of these two biomarkers might be of greater value than application of a single marker to identify patients at high risk, even at an early clinical stage.

Constitutive and inducible nuclear factor-κB in immortalized normal human bronchial epithelial and non-small cell lung cancer cell lines

Constitutive activation of the proinflammatory nuclear factor kappaB (NF-kappaB) transcription factor p65(RelA)/p50 has been implicated in many cancers, including leukemias, lymphomas, and several solid tumors, including lung cancer. In many cases, constitutive NF-kappaB activation can be recapitulated in cell lines isolated from these cancers. To test whether this is the case with non-small cell lung cancer (NSCLC) cell lines, we investigated the basal levels of NF-kappaB proteins, their subcellular distribution, their DNA-binding activities, and the expression of NF-kappaB-responsive genes in 10 NSCLC cell lines. The immortalized human bronchial epithelial cell line BEAS-2B served as a normal control. We found little evidence of substantial constitutive NF-kappaB activation in NSCLC cell lines, although most all of the normal and NSCLC cells possessed inducible NF-kappaB. Our findings provide a resource for the use of particular NSCLC cell lines for the investigation of constitutive and inducible NF-kappaB activity in vitro.

Effect of celecoxib and novel agent LC-1 in a hamster model of lung cancer

BACKGROUND

Lung cancer is the leading cause of cancer deaths in the United States. Inflammatory molecules, cyclooxygenase-2 (COX-2) and nuclear factor kappa B (NF-kappaB) have been implicated in lung carcinogenesis. The therapeutic potential of celecoxib, a COX-2 selective inhibitor, and LC-1, a pro-apoptotic drug with accompanying inhibition of NF-kappaB, were investigated.

MATERIALS AND METHODS

Syrian golden hamsters (n = 140) underwent N-nitroso-bis(2-oxopropyl)amine (BOP) injection weekly for 6 wk. Hamsters were randomized into seven groups: placebo and low/high doses of LC-1, celecoxib, and LC-1/celecoxib. Treatments were given via orogastric lavage for 32 wk. Immunohistochemistry was used to determine COX-2 expression and NF-kappaB activity. Ki-67 labeling was used as an index of proliferation. COX activity was measured by prostaglandin E(2) enzyme-linked immunosorbent assay.

RESULTS

BOP successfully induced lung adenocarcinoma in 63% of placebo animals. Lung tumors strongly expressed COX-2 and NF-kappaB. Prostaglandin E(2) levels were decreased in celecoxib compared with placebo groups (P < 0.05) reflecting suppression of COX activity, but no decrease in NF-kappaB was seen as measured by immunohistochemistry in the tumors. There was no significant difference in tumor size, tumor incidence, or tumor proliferation index between placebo and treatment groups.

CONCLUSIONS

Carcinogen exposure results in increased COX-2 and NF-kappaB expression and suggests a role in carcinogenesis. Celecoxib and LC-1 did not have any effect in preventing lung cancer development when co-administered with and continued after the carcinogen BOP. Higher doses that can result in suppression of NF-kappaB activity will need to be explored to determine the viability of this approach to prevent lung cancer development.