Inflammation as a tumor promoter in cancer induction

The adaptive immune response to sporadic cancer

Most of the current experimental cancer models do not reflect the pathophysiology of real-life cancer. Cancer usually occurs sporadically and is clonal in origin. Between tumor initiation and progression, clinically unapparent pre-malignant cells may persist for years or decades in humans. Recently, mouse models of sporadic cancer have been developed. The mouse germ-line can be engineered with high precision so that defined genes can be switched on and off in the adult organism in a targeted manner. Analysis of the immune response against sporadic tumors requires the knowledge of a tumor antigen. Ideally, a silent oncogene, for which the mice are not tolerant, is stochastically activated in individual cells. This approach offers the opportunity to analyze the adaptive immune response throughout the long process of malignant transformation and most closely resembles cancer in humans. In such a model with the highly immunogenic SV40 large T antigen as a dormant oncogene, we discovered that sporadic cancer is recognized by the adaptive immune system at the pre-malignant stage, concomitant with the induction of tumor antigen-specific tolerance. These results demonstrated that even highly immunogenic sporadic tumors are unable to induce functional cytotoxic T lymphocytes. Based on this model, we conclude that immunosurveillance plays little or no role against sporadic cancer and that tumors must not escape immune recognition or destruction.

Role of tumor necrosis factor-alpha and TRAIL in high-dose radiation-induced bystander signaling in lung adenocarcinoma

In the present study, ionizing radiation (IR)-induced bystander effects were investigated in two lung cancer cell lines. A549 cells were found to be more resistant to radiation-conditioned medium (RCM) obtained from A549 cells when compared with the H460 exposed to RCM procured from H460 cells. Significant release of tumor necrosis factor-alpha (TNF-alpha) was observed in A549 cells after IR/RCM exposure, and the survival was reversed with neutralizing antibody against TNF-alpha. In H460 cells, significant release of TNF-related apoptosis-inducing ligand (TRAIL), but not TNF-alpha, was observed in response to IR, RCM exposure, or RCM + 2Gy, and neutralizing antibody against TRAIL diminished clonogenic inhibition. Mechanistically, TNF-alpha present in RCM of A549 was found to mediate nuclear factor-kappaB (NF-kappaB) translocation to nucleus, whereas the soluble TRAIL present in RCM of H460 cells mobilized the nuclear translocation of PAR-4 (a proapoptotic protein). Analysis of IR-inducible early growth response-1 (EGR-1) function showed that EGR-1 was functional in A549 cells but not in H460 cells. A significant decrease in RCM-mediated apoptosis was observed in both A549 cells stably expressing small interfering RNA EGR-1 and EGR-1(-/-) mouse embryonic fibroblast cells. Thus, the high-dose IR-induced bystander responses in A549 may be dependent on the EGR-1 function and its target gene TNF-alpha. These findings show that the reduced bystander response in A549 cells is due to activation of NF-kappaB signaling by TNF-alpha, whereas enhanced response to IR-induced bystander signaling in H460 cells was due to release of TRAIL associated with nuclear translocation of PAR-4.

A systematic review of the association between circulating concentrations of C reactive protein and cancer

The objective of this study was to review and summarise the published evidence for an association between circulating concentrations of C reactive protein (CRP) and cancer through a systematic review. 90 discrete studies were identified. 81 (90%) were prevalent case-control or cross-sectional studies, and only 9 studies had a prospective design. In most prevalent studies, CRP concentrations were found to be higher in patients with cancer than in healthy controls or controls with benign conditions. Of the nine large prospective studies identified in this review, four reported no relationship between circulating CRP levels and breast, prostate or colorectal cancers, and five studies found that CRP was associated with colorectal or lung cancers. Most of the studies evaluating CRP as a diagnostic marker of cancer did not present relevant statistical analyses. Furthermore, any association reported in the prevalent studies might reflect reverse causation, survival bias or confounding. The prospective studies provided no strong evidence for a causal role of CRP in cancer. Instead of further prevalent studies, more large prospective studies and CRP gene-cancer association studies would be valuable in investigating the role of CRP in cancer.

Activation of IkappaB kinase and NF-kappaB is essential for Helicobacter pylori-induced chronic gastritis in Mongolian gerbils

The Mongolian gerbil model of Helicobacter pylori infection resembles human gastritis. In this study, we investigated the role of NF-kappaB activation in H. pylori-infected gerbils. Activated macrophages were significantly increased in H. pylori-infected gastric mucosa and were identified as being important cells with potent activation of NF-kappaB, which plays an important part in producing proinflammatory cytokines. Macrophage depletion by the administration of clodronate resulted in milder inflammation in gerbils infected with H. pylori. In macrophages, the inhibition of IkappaB kinase beta (IKKbeta), which is a critical kinase for NF-kappaB activation, resulted in lower proinflammatory cytokine expression caused by heat-killed H. pylori cells. Furthermore, treatment with IKKbeta inhibitor resulted in milder inflammation in gerbils with H. pylori gastritis. Collectively, our data suggest that H. pylori-mediated gastric inflammation critically depends on the efficient recruitment and activation of macrophages, with sufficient NF-kappaB activation.

Mesenchymal stem cells in cancer: tumor-associated fibroblasts and cell-based delivery vehicles

Recent evidence suggests that mesenchymal stem cells (MSC) selectively home to tumors, where they contribute to the formation of tumor-associated stroma. This effect can be opposed by genetically modifying MSC to produce high levels of anti-cancer agents that blunt tumor growth kinetics and inhibit the growth of tumors in situ. In this review article, we describe the biological properties of MSC within the tumor microenvironment and discuss the potential use of MSC and other bone marrow-derived cell populations as delivery vehicles for antitumor proteins.

Joint effect between regular use of non-steroidal anti-inflammatory drugs, variants in inflammatory genes and risk of lymphoma

OBJECTIVE

Limited evidence suggests the importance of inflammatory processes for the etiology of lymphomas. To further research in this area, we investigated the role of genetic variants in key inflammatory factors, non-steroidal anti-inflammatory drug [NSAID] use, and their joint effect in lymphomagenesis.

METHODS

The study comprised 710 case-control pairs, matched for gender, age, and study region. We examined the association of regular NSAID use and polymorphisms in prostaglandin-endoperoxide synthase-2 (COX2), prostaglandin E synthase (PTGES), interleukin-1 alpha (IL1A), IL-1 beta (IL1B), and IL-1 receptor antagonist (IL1RA), and lymphoma risk by applying logistic regression to calculate odds ratios (OR) and 95% confidence intervals (95% CI).

RESULTS

Regular NSAID use was associated with a slightly reduced risk of B-NHL (OR = 0.8, 95% CI = 0.6-1.1). For T-NHL, the COX2 rs2745557 A-allele conferred a 2.2-fold (95% CI = 1.1-4.5) and homozygosis for the IL1RN rs454078 T-allele was associated with a 4.5-fold (95% CI = 1.4-13.9) elevated risk, however, based on sparse data. IL1 haplotype 5 was associated with a statistically significant 43% increased risk for B-NHL among non-regular users of NSAIDs, but a 70% decreased risk for regular users (p-value for interaction < 0.001).

CONCLUSIONS

These results suggest the relevance of joint effects between NSAID use and IL1 haplotypes on the risk of B-NHL.

The endothelial cell-produced antiangiogenic cytokine vascular endothelial growth inhibitor induces dendritic cell maturation

Angiogenesis is an essential component of chronic inflammation that is linked to carcinogenesis. In this study, we report that human vascular endothelial growth inhibitor (VEGI, TNF superfamily 15), an endothelial cell-produced antiangiogenic cytokine, induces mouse dendritic cell (DC) maturation, a critical event in inflammation-initiated immunity. VEGI-stimulated bone marrow-derived immature DCs display early activation of maturation signaling molecules NF-kappaB, STAT3, p38, and JNK, and cytoskeleton reorganization and dendrite formation. The activation signals are partially inhibited by using a neutralizing Ab against death domain-containing receptor-3 (DR3) or a truncated form of DR3 consisting of the extracellular domain, indicating an involvement of DR3 in the transmission of VEGI activity. A VEGI isoform, TL1A, does not induce similar activities under otherwise identical experimental conditions. Additionally, the cells reveal significantly enhanced expression of mature DC-specific marker CD83, secondary lymphoid tissue-directing chemokine receptor CCR7, the MHC class-II protein (MHC-II), and costimulatory molecules CD40, CD80, and CD86. Functionally, the cells exhibit decreased Ag endocytosis, increased cell surface distribution of MHC-II, and increased secretion of IL-12 and TNF. Moreover, VEGI-stimulated DCs are able to facilitate the differentiation of CD4+ naive T cells in cocultures. These findings suggest that the anticancer activity of VEGI arises from coupling the inhibition of endothelial cell growth with the promotion of the adaptive immune mechanisms through the stimulation of DC maturation.

Current topics in the epidemiology of oral cavity and oropharyngeal cancers

Oral cancer incidence rates rose dramatically during the twentieth century in the United States and Europe, especially among individuals under the age of 60 years. Although influenced by age, sex, and country of origin, incidence trends were most strongly affected by elevated risk among individuals born after approximately 1915. This cohort effect was indicative of strong behavioral influences on oral cancer risk. In this article, associations between oral cancer risk and established behavioral risk factors including alcohol and tobacco use are reviewed. Additionally, possible associations between oral cancer risk and oral hygiene, diet, nutritional status, and sexual behavior as well as the influence of genetic factors on oral cancer risk are considered. Special emphasis is placed on evaluating possible risk differences in individuals above and below the age of 45 and in users and nonusers of alcohol and tobacco.

Inflammation: its role and interplay in the development of cancer, with special focus on gynecological malignancies

The relationship between inflammation and cancer is intriguing. Mechanisms contributing to the pathobiology of carcinogenesis are multiple and complex. Many aspects still elude researchers and are subjects of intense speculation and debate, for example, the triggering factor for malignant transformation in inflammation. A comprehensive literature search was conducted from the Web sites of the National Library of Medicine and Pubmed Central, the US National Library of Medicine's digital archive of life sciences literature. The data were accessed from books and journals that published recent articles in this field. Several recent studies have identified nuclear factor-kappa B as a key modulator in driving inflammation to cancers. An inflammatory microenvironment inhabiting various inflammatory cells and a network of signaling molecules is essential for the malignant progression of transformed cells. This is attributed to the mutagenic predisposition of persistent infection-fighting agents at sites of chronic inflammation. The appreciation of the role of inflammation in carcinogenesis provides a mechanistic framework to understand clinical benefits of newer therapeutic strategies An in-depth knowledge about various pathogenic mechanisms involved in cancer will help clinicians in better management of the disease.

Decreased c-kit function inhibits enhanced skin carcinogenesis in c-Ha-ras protooncogene transgenic mice

We previously showed that rasH2 transgenic mice carrying the human c-Ha-ras protooncogene are highly susceptible to chemical skin carcinogenesis. In the dermis of rasH2 mice, mast cells are recruited constitutively, and the number of mast cells increases more than in wild-type mice in response to treatment with 7,12-dimethylbenz[a]anthracene and 12-O-tetradecanoylphorbol-13-acetate. To determine whether enhanced skin tumor development in rasH2 mice is dependent on the recruitment of mast cells, we generated rasH2 KIT(W/Wv) mice by crossing rasH2 mice and W or W(v) KIT mutants, and examined the chemical skin carcinogenesis. In rasH2 KIT(W/Wv) mice, mast cells were not found in the dermis either before or after treatment with 7,12-dimethylbenz[a]anthracene and 12-O-tetradecanoylphorbol-13-acetate. Papilloma multiplicity was up to 4.6-fold higher in rasH2 KIT(+/+) mice compared with their rasH2 KIT(W/Wv) siblings. At 12 weeks after the experiment began, the volumes of tumors were significantly smaller in rasH2 KIT(W/Wv) relative to rasH2 KIT(+/+) mice (rasH2 KIT(W/Wv): 29.2 +/- 19.9 mm(3) versus rasH2 KIT(+/+): 179.6 +/- 726.6 mm(3); P = 0.0153). There was no difference in the latency or multiplicity of papillomas between mice without the rasH2 transgene, KIT(W/Wv) mice and their wild-type littermates. Western blot analysis showed that expression of H-RAS protein in the skin was equivalent in rasH2 KIT(W/Wv) and rasH2 KIT(+/+) mice. In conclusion, the inhibition of c-kit decreased H-ras-induced skin carcinogenesis. The suppression of c-kit may be a unique and effective target as a preclinical model of cancer treatment where the activation of H-ras has a significant role. Targeting mast cells could also be a potential strategy for treating malignancies.

Cyclooxygenase-2 (cox-2) and the inflammogenesis of cancer

Cohesive scientific evidence from molecular, animal, and human investigations supports the hypothesis that aberrant induction of COX-2 and up-regulation of the prostaglandin cascade play a significant role in carcinogenesis, and reciprocally, blockade of the process has strong potential for cancer prevention and therapy. Supporting evidence includes the following: [1] expression of constitutive COX-2-catalyzed prostaglandin biosynthesis is induced by most cancer-causing agents including tobacco smoke and its components (polycylic aromatic amines, heterocyclic amines, nitrosamines), essential polyunsaturated fatty acids (unconjugated linoleic acid), mitogens, growth factors, proinflammatory cytokines, microbial agents, tumor promoters, and other epigenetic factors, [2] COX-2 expression is a characteristic feature of all premalignant neoplasms, [3] COX-2 expression is a characteristic feature of all malignant neoplasms, and expression intensifies with stage at detection and cancer progression and metastasis, [4] all essential features of carcinogenesis (mutagenesis, mitogenesis, angiogenesis, reduced apoptosis, metastasis, and immunosuppression) are linked to COX-2-driven prostaglandin (PGE-2) biosynthesis, [5] animal studies show that COX-2 up-regulation (in the absence of genetic mutations) is sufficient to stimulate the transformation of normal cells to invasive cancer and metastatic disease, [6] non-selective COX-2 inhibitors, such as aspirin and ibuprofen, reduce the risk of human cancer and precancerous lesions, and [7] selective COX-2 inhibitors, such as celecoxib, reduce the risk of human cancer and precancerous lesions at all anatomic sites thus far investigated. Results confirming that COX-2 blockade is effective for both cancer prevention and therapy have been tempered by observations that some COX2 inhibitors pose a risk to the cardiovascular system, and more studies are needed in order to determine if certain of these drugs can be taken at dosages that prevent cancer without increasing cardiovascular risk. It is emphasized that the "inflammogenesis model of cancer" is not mutually exclusive and may in fact be synergistic with the accumulation of somatic mutations in tumor suppressor genes and oncogenes or epigenetic factors in the development of cancer.

Anti-inflammatory property of the urinary metabolites of nobiletin in mouse

Nobiletin, a major component of polymethoxyflavones in citrus fruits, has a broad spectrum of health beneficial properties including anti-inflammatory and anti-carcinogenic activities. The metabolite identification of nobiletin in mouse urine has concluded that it undergoes mono-demethylation (3'- and 4'-demethylnobiletin) and di-demethylation (3',4'-didemethylnobiletin) metabolic pathway. Biological screening of nobiletin and its metabolites has revealed that the metabolites possess more potent anti-inflammatory activity than their parent compound. Therefore, this letter reports the identification of nobiletin metabolites and their anti-inflammatory activity against LPS-induced NO production and iNOS, COX-2 protein expression in RAW264.7 macrophage.

Essential roles of high-mobility group box 1 in the development of murine colitis and colitis-associated cancer

High-mobility group box 1 (HMGB1) is a nuclear factor released extracellularly as a proinflammatory cytokine. We measured the HMGB1 concentration in the sera of mice with chemically induced colitis (DSS; dextran sulfate sodium salt) and found a marked increase. Inhibition of HMGB1 by neutralizing anti-HMGB1 antibody resulted in reduced inflammation in DSS-treated colons. In macrophages, HMGB1 induces several proinflammatory cytokines, such as IL-6, which are regulated by NF-kappaB activation. Two putative sources of HMGB1 were explored: in one, bacterial factors induce HMGB1 secretion from macrophages and in the other, necrotic epithelial cells directly release HMGB1. LPS induced a small amount of HMGB1 in macrophages, but macrophages incubated with supernatant prepared from necrotic cells and containing large amounts of HMGB1 activated NF-kappaB and induced IL-6. Using the colitis-associated cancer model, we demonstrated that neutralizing anti-HMGB1 antibody decreases tumor incidence and size. These observations suggest that HMGB1 is a potentially useful target for IBD treatment and the prevention of colitis-associated cancer.

C-reactive protein concentrations and subsequent ovarian cancer risk

OBJECTIVE

To estimate the association between prediagnostic levels of C-reactive protein (CRP), a marker of chronic systemic inflammation, and subsequent development of ovarian cancer.

METHODS

A multicenter, nested, case-control study was conducted, including women who developed ovarian cancer (case patients) and women who were cancer-free (controls) from the following cohorts: CLUE ("Give us a CLUE to cancer and heart disease") cohorts of Washington County, Maryland, the Columbia, Missouri Serum Bank, and the Island of Guernsey Prospective Study, United Kingdom. A total of 167 incident invasive epithelial ovarian cancer cases were identified and each matched to an average of two controls on cohort, age, race, menopausal status, time since last menstrual period, current hormone use, date of recruitment, and time of day of blood draw. Baseline serum samples were assayed for CRP concentrations, and estimates of risk associated with CRP levels were assessed using conditional logistic regression.

RESULTS

Ovarian cancer risk was positively associated with increasing CRP concentrations. The risk of developing ovarian cancer among women in the highest third of the distribution of CRP compared with those in the lowest third was 1.72 (95% confidence interval 1.06-2.77), with evidence of an increasing risk with increasing concentration of CRP (P trend=0.02). Similar associations were observed using established clinical CRP cutpoints for heart disease risk (odds ratio 2.03, 95% confidence interval 1.20-3.47 for 3-10 mg/L compared with less than 1 mg/L, P trend=.008). If this association is causal, roughly 23% of ovarian cancer cases are attributed to chronic inflammation as indicated by elevated CRP concentrations.

CONCLUSION

Higher circulating CRP concentrations in women who subsequently developed ovarian cancer support the hypothesized role of chronic inflammation in ovarian carcinogenesis.

LEVEL OF EVIDENCE

II.

Angiogenesis and chronic inflammation: cause or consequence?

Evidence has been gathered regarding the association between angiogenesis and inflammation in pathological situations. These two phenomena have long been coupled together in many chronic inflammatory disorders with distinct etiopathogenic origin, including psoriasis, rheumatoid arthritis, Crohn's disease, diabetes, and cancer. Lately, this concept has further been substantiated by the finding that several previously established non-inflammatory disorders, such as osteoarthritis and obesity, display both inflammation and angiogenesis in an exacerbated manner. In addition, the interplay between inflammatory cells, endothelial cells and fibroblasts in chronic inflammation sites, together with the fact that inflammation and angiogenesis can actually be triggered by the same molecular events, further strengthen this association. Therefore, elucidating the underlying cellular and molecular mechanisms that gather together the two processes is mandatory in order to understand their synergistic effect, and to develop new therapeutic approaches for the management of these disorders that cause a great deal of discomfort, disability, and in some cases death.

Immunoinflammatory mechanisms in lung cancer development: is leptin a mediator?

This is a short review focusing on leptin immunoinflammatory mechanisms that ultimately may contribute to lung cancer development. We explored the complex and intricate interaction of leptin with immune cells to propose a pathway of inflammation-associated lung cancer development.

Characterizing tumor-promoting T cells in chemically induced cutaneous carcinogenesis

There is a longstanding but poorly understood epidemiologic link between inflammation and cancer. Consistent with this, we previously showed that alphabeta T cell deficiency can increase resistance to chemical carcinogenesis initiated by 7,12-dimethylbenz[a]anthracene and promoted by phorbol 12-myristate 13-acetate. This provoked the hypothesis that alphabeta T cell deficiency removed T regulatory cells that limit the anti-tumor response or removed a specific tumor-promoting (T-pro) T cell population. Here we provide evidence for the latter, identifying a novel CD8(+) subset that is a candidate for T-pro cells. We demonstrate that CD8 cell-deficient mice show substantially less tumor incidence and progression to carcinoma, whereas susceptibility is restored by CD8(+) cell reconstitution. To characterize the putative T-pro cells, tumor-infiltrating lymphocytes were isolated from normal and CD4(-/-) mice, revealing an activated population of T cell receptor alphabeta(+)CD8(+)CD44(+)CD62L(-) cells expressing the inflammatory mediators IFNgamma, TNFalpha, and cyclooxygenase-2, but deficient in perforin, relative to recirculating cells of equivalent phenotype. This novel population of CD8(+) T cells has intriguing similarities with other lymphocytes that have been associated with tissue growth and invasiveness and has implications for inflammation-associated carcinogenesis, models of cancer immunosurveillance, and immunotherapeutic strategies.

Tumor necrosis factor-alpha stimulates focal adhesion kinase activity required for mitogen-activated kinase-associated interleukin 6 expression

Focal adhesion kinase (FAK) is a cytoplasmic protein-tyrosine kinase that promotes cell migration, survival, and gene expression. Here we show that FAK signaling is important for tumor necrosis factor-alpha (TNFalpha)-induced interleukin 6 (IL-6) mRNA and protein expression in breast (4T1), lung (A549), prostate (PC-3), and neural (NB-8) tumor cells by FAK short hairpin RNA knockdown and by comparisons of FAK-null (FAK(-/-)) and FAK(+/+) mouse embryo fibroblasts. FAK promoted TNFalpha-stimulated MAPK activation needed for maximal IL-6 production. FAK was not required for TNFalpha-mediated nuclear factor-kappaB or c-Jun N-terminal kinase activation. TNFalpha-stimulated FAK catalytic activation and IL-6 production were inhibited by FAK N-terminal but not FAK C-terminal domain overexpression. Analysis of FAK(-/-) fibroblasts stably reconstituted with wild type or various FAK point mutants showed that FAK catalytic activity, Tyr-397 phosphorylation, and the Pro-712/713 proline-rich region of FAK were required for TNFalpha-stimulated MAPK activation and IL-6 production. Constitutively activated MAPK kinase-1 (MEK1) expression in FAK(-/-) and A549 FAK short hairpin RNA-expressing cells rescued TNFalpha-stimulated IL-6 production. Inhibition of Src protein-tyrosine kinase activity or mutation of Src phosphorylation sites on FAK (Tyr-861 or Tyr-925) did not affect TNFalpha-stimulated IL-6 expression. Moreover, analyses of Src(-/-), Yes(-/-), and Fyn(-/-) fibroblasts showed that Src expression was inhibitory to TNFalpha-stimulated IL-6 production. These studies provide evidence for a novel Src-independent FAK to MAPK signaling pathway regulating IL-6 expression with potential importance to inflammation and tumor progression.

A novel N-alkylated prodigiosin analogue induced death in tumour cell through apoptosis or necrosis depending upon the cell type

PURPOSE

To investigate the mechanism of cell death induced by the N-alkylated prodigiosin analogue, 2,2'-[3-methoxy-1'amyl-5'-methyl-4-(1''-pyrryl)] dipyrryl-methene (MAMPDM) in S-180 and EL-4 tumour cell lines.

METHODS

Effect of MAMPDM on cell viability was assessed by MTT dye conversion. Induction of apoptosis was assessed by monitoring caspase 3 activity using a fluorogenic substrate, fragmentation of DNA by gel electrophoresis and sub-diploid DNA containing cells by flowcytometry. Necrosis was estimated by flowcytometric analysis of the uptake of propidium iodide.

RESULTS

MAMPDM inhibited the proliferation of murine fibrosarcoma, S-180 cells and induced cell death. Investigations into the mechanism of cell death by MAMPDM in S-180 cells showed absence of hallmarks of apoptotic cell death such as activation of caspase 3, DNA fragmentation and presence of cells with sub-diploid DNA content. However, there was a rapid loss of membrane integrity as assessed by uptake of propidium iodide, which is characteristic of necrosis. In contrast to induction of necrosis in S-180 cells, MAMPDM induced apoptotic cell death in EL-4 cells as evident by activation of caspase 3, fragmentation of DNA and sub-diploid DNA containing cells.

CONCLUSIONS

MAMPDM could induce cell death by either apoptosis or necrosis depending upon the cell type. This would be of advantage in elimination of tumor cells defective in apoptotic pathway and therefore, refractory to the conventional therapies.

Expression of novel p53 isoforms in oral lichen planus

Oral lichen planus (OLP) is a chronic inflammatory disease of unknown origin, showing little spontaneous regression. WHO classifies OLP as a premalignant condition, however, the underlying mechanisms initiating development of cancer in OLP lesions are not understood. The p53 tumour suppressor plays an important role in many tumours, and an increased expression of p53 protein has been seen in OLP lesions. Recently it was shown that the human TP53 gene encodes at least nine different isoforms. Another member of the p53 family, p63, comprises six different isoforms and plays a crucial role in the formation of oral mucosa, salivary glands, teeth and skin. It has also been suggested that p63 is involved in development of squamous cell carcinoma of the head and neck (SCCHN). In contrast to p53, a decreased expression of p63 protein has been seen in OLP lesions. In this study, we mapped the expression of five novel p53 isoforms at RNA and protein levels in OLP and matched normal controls. In the same samples we also measured levels of p63 isoforms using quantitative RT–PCR. Results showed p53 to be expressed in all OLP lesions and normal tissues. The p53β and Δ133p53 isoforms were expressed in the majority of samples whereas the remaining three novel isoforms analysed were expressed in only a few samples. Levels of p63 isoforms were lower in OLP lesions compared with normal tissue, however, changes were not statistically significant.

The chemopreventive polyphenol Curcumin prevents hematogenous breast cancer metastases in immunodeficient mice

Dissemination of metastatic cells probably occurs long before diagnosis of the primary tumor. Metastasis during early phases of carcinogenesis in high risk patients is therefore a potential prevention target. The plant polyphenol Curcumin has been proposed for dietary prevention of cancer. We therefore examined its effects on the human breast cancer cell line MDA-MB-231 in vitroand in a mouse metastasis model. Curcumin strongly induces apoptosis in MDA-MB-231 cells in correlation with reduced activation of the survival pathway NFkappaB, as a consequence of diminished IotakappaB and p65 phosphorylation. Curcumin also reduces the expression of major matrix metalloproteinases (MMPs) due to reduced NFkappa B activity and transcriptional downregulation of AP-1. NFkappa B/p65 silencing is sufficient to downregulate c-jun and MMP expression. Reduced NFkappa B/AP-1 activity and MMP expression lead to diminished invasion through a reconstituted basement membrane and to a significantly lower number of lung metastases in immunodeficient mice after intercardiac injection of 231 cells (p=0.0035). 68% of Curcumin treated but only 17% of untreated animals showed no or very few lung metastases, most likely as a consequence of down-regulation of NFkappa B/AP-1 dependent MMP expression and direct apoptotic effects on circulating tumor cells but not on established metastases. Dietary chemoprevention of metastases appears therefore feasible.

Inflammation and cancer: is trophism the link?

The pathophysiological mechanisms of the inflammatory response can be common to wound repair and tumor development. We propose that this response evolves in three phases, the nervous or immediate phase, the immune or intermediate phase, and the endocrine or late phase. In wound repair and in these phases, the interstitial space successively presents edema due to ischemia-revascularization and nutrition by diffusion (nervous phase), infiltration by leukocytes, which would mediate the nutrition of damaged neighbor cells (immune phase) and by angiogenesis, nutrition mediated by the capillaries that favor regeneration or scarring (endocrine phase). At the same time, in tumor development, it is considered that the cancerous cell successively occupies the interstitial space, expressing three different phenotypes: the hypoxia-reperfusion phenotype, with anaerobic glycolisis, oxidative stress and edema (dormant stage); the immune phenotype that expresses the functions corresponding to leukocytes, including the hyperproduction of pro-inflammatory mediators, lymphangiogenesis, the invasion of lymph nodes (N stage) and systemic inflammatory response syndrome; and lastly, the endocrine phenotype, in which the appearance of both local (tumor or T stage) and systemic (metastasis or M stage) angiogenesis induce a growing disease.

Glycogen synthase kinase-3 (GSK3): inflammation, diseases, and therapeutics

Deciphering what governs inflammation and its effects on tissues is vital for understanding many pathologies. The recent discovery that glycogen synthase kinase-3 (GSK3) promotes inflammation reveals a new component of its well-documented actions in several prevalent diseases which involve inflammation, including mood disorders, Alzheimer's disease, diabetes, and cancer. Involvement in such disparate conditions stems from the widespread influences of GSK3 on many cellular functions, with this review focusing on its regulation of inflammatory processes. GSK3 promotes the production of inflammatory molecules and cell migration, which together make GSK3 a powerful regulator of inflammation, while GSK3 inhibition provides protection from inflammatory conditions in animal models. The involvement of GSK3 and inflammation in these diseases are highlighted. Thus, GSK3 may contribute not only to primary pathologies in these diseases, but also to the associated inflammation, suggesting that GSK3 inhibitors may have multiple effects influencing these conditions.

Inflammation, cancer and chemoresistance: taking advantage of the toll-like receptor signaling pathway

The association between chronic inflammation and cancer has long been observed. Furthermore, NF-kappaB activation and the subsequent production of cytokines, chemokines, growth factors, and antiapoptotic proteins has been found to be involved in cancer progression and chemoresistance. However, the signals inducing NF-kappaB in cancer cells are still not well understood. Here, we reviewed the association between chronic inflammation and cancer, the role of NF-kappaB and its inhibitors as potential anticancer drugs, and Toll-like receptors as possible signal initiators for NF-kappaB activation and inflammation-induced carcinogenesis and chemoresistance. Furthermore, we propose that, the stimulation of Toll-like receptors by microbial components and/or endogenous ligands may represent the initial signal promoting a proinflammatory environment that will enhance tumor growth and chemoresistance.

The TNF-alpha 238A polymorphism is associated with susceptibility to persistent bone marrow dysplasia following chronic exposure to benzene

Chronic exposure to benzene can result in transient hematotoxicity (benzene poisoning, BP) or persistent bone marrow pathology including dysplasia and/or acute myeloid leukemia. We recently described a persistent bone marrow dysplasia with unique dysplastic and inflammatory features developing in individuals previously exposed to benzene (BID) [Irons RD, Lv L, Gross SA, Ye X, Bao L, Wang XQ, et al. Chronic exposure to benzene results in a unique form of dysplasia. Leuk Res 2005;29:1371-80]. In this study we investigated the association of single nucleotide polymorphisms (SNP) (-863 (C-->A), -857 (C-->T), -308 (G-->A), -238 (G-->A)) in the promoter region of the cytokine, tumor necrosis factor-alpha (TNF-alpha) on the development of BP, persistent BID and de novo myelodysplastic syndrome (MDS) in 394 individuals. Only the -238 (G-->A) polymorphism was significantly associated with the development of BID (odds ratio (OR)=7.4; 95% C.I. 1.23-44.7) and was specific for BID and not de novo MDS or BP. These findings are consistent with a role for inflammation in the development of BID and suggest that cell-specific alterations in TNF-alpha expression may promote clonal selection in the evolution of neoplastic hematopoietic disease.

Humulone inhibits phorbol ester-induced COX-2 expression in mouse skin by blocking activation of NF-κB and AP-1: IκB kinase and c-Jun-N-terminal kinase as respective potential upstream targets

Humulone, a bitter acid derived from hop (Humulus lupulus L.), possesses antioxidative, anti-inflammatory and other biologically active activities. Although humulone has been reported to inhibit chemically induced mouse skin tumor promotion, the underlying mechanisms are yet to be elucidated. Since an inappropriate over-expression of cyclooxygenase-2 (COX-2) is implicated in carcinogenesis, we investigated effects of humulone on COX-2 expression in mouse skin stimulated with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA). Topical application of humulone (10 mumol) significantly inhibited TPA-induced epidermal COX-2 expression. Humulone also diminished TPA-induced DNA binding of nuclear factor-kappaB (NF-kappaB) and activator protein-1 (AP-1). Pre-treatment with humulone attenuated TPA-induced phosphorylation of p65 and nuclear translocation of NF-kappaB subunit proteins. Humulone blunted TPA-induced activation of inhibitory kappaB (IkappaB) kinase (IKK) in mouse skin, which accounts for its suppression of phosphorylation and subsequent degradation of IkappaBalpha. An in vitro kinase assay revealed that humulone could directly inhibit the catalytic activity of IKKbeta. Humulone suppressed the activation of mitogen-activated protein kinases (MAPKs) in TPA-treated mouse skin. The roles of extracellular signal-regulated protein kinase-1/2 and p38 MAPK in TPA-induced activation of NF-kappaB in mouse skin had been defined in our previous studies. The present study revealed that topical application of SP600125, a pharmacological inhibitor of c-Jun-N-terminal kinase (JNK), abrogated the activation of AP-1 and the expression of COX-2 in TPA-treated mouse skin. Taken together, humulone suppressed TPA-induced activation of NF-kappaB and AP-1 and subsequent expression of COX-2 by blocking upstream kinases IKK and JNK, respectively, which may account for its antitumor-promoting effects on mouse skin carcinogenesis.

Frequencies of single nucleotide polymorphisms in genes regulating inflammatory responses in a community-based population

BACKGROUND

Allele frequencies reported from public databases or articles are mostly based on small sample sizes. Differences in genotype frequencies by age, race and sex have implications for studies designed to examine genetic susceptibility to disease. In a community-based cohort of 9,960 individuals, we compared the allele frequencies of 49 single nucleotide polymorphisms (SNPs) of genes involved in inflammatory pathways to the frequencies reported on public databases, and examined the genotypes frequencies by age and sex. The genes in which SNPs were analyzed include CCR2, CCR5, COX1, COX2, CRP, CSF1, CSF2, IFNG, IL1A, IL1B, IL2, IL4, IL6, IL8, IL10, IL13, IL18, LTA, MPO, NOS2A, NOS3, PPARD, PPARG, PPARGC1 and TNF.

RESULTS

Mean(SD) age was 53.2(15.5); 98% were Caucasians and 62% were women. Only 1 out of 33 SNPs differed from the SNP500Cancer database in allele frequency by >10% in Caucasians (n = 9,831), whereas 12 SNPs differed by >10% (up to 50%) in African Americans (n = 105). Two out of 15 SNPs differed from the dbSNP database in allele frequencies by >10% in Caucasians, and 5 out of 15 SNPs differed by >10% in African Americans. Age was similar across most genotype groups. Genotype frequencies did not differ by sex except for TNF(rs1799724), IL2(rs2069762), IL10(rs1800890), PPARG(rs1801282), and CRP(rs1800947) with differences of less than 4%.

CONCLUSION

When estimating the size of samples needed for a study, particularly if a reference sample is used, one should take into consideration the size and ethnicity of the reference sample. Larger sample size is needed for public databases that report allele frequencies in non-Caucasian populations.

The involvement of IL-1 in tumorigenesis, tumor invasiveness, metastasis and tumor-host interactions

Interleukin-1 (IL-1) includes a family of closely related genes; the two major agonistic proteins, IL-1alpha and IL-1beta, are pleiotropic and affect mainly inflammation, immunity and hemopoiesis. The IL-1Ra antagonist is a physiological inhibitor of pre-formed IL-1. Recombinant IL-1alpha and IL-1beta bind to the same receptors and induce the same biological functions. As such, the IL-1 molecules have been considered identical in normal homeostasis and in disease. However, the IL-1 molecules differ in their compartmentalization within the producing cell or the microenvironment. Thus, IL-1beta is solely active in its secreted form, whereas IL-1alpha is mainly active in cell-associated forms (intracellular precursor and membrane-bound IL-1alpha) and only rarely as a secreted cytokine, as it is secreted only in a limited manner. IL-1 is abundant at tumor sites, where it may affect the process of carcinogenesis, tumor growth and invasiveness and also the patterns of tumor-host interactions. Here, we review the effects of microenvironment- and tumor cell-derived IL-1 on malignant processes in experimental tumor models and in cancer patients. We propose that membrane-associated IL-1alpha expressed on malignant cells stimulates anti-tumor immunity, while secretable IL-1beta, derived from the microenvironment or the malignant cells, activates inflammation that promotes invasiveness and also induces tumor-mediated suppression. Inhibition of the function of IL-1 by the IL-1Ra, reduces tumor invasiveness and alleviates tumor-mediated suppression, pointing to its feasibility in cancer therapy. Differential manipulation of IL-1alpha and IL-1beta in malignant cells or in the tumor's microenvironment can open new avenues for using IL-1 in cancer therapy.

Interleukin-1beta-driven inflammation promotes the development and invasiveness of chemical carcinogen-induced tumors

The role of microenvironment interleukin 1 (IL-1) on 3-methylcholanthrene (3-MCA)-induced carcinogenesis was assessed in IL-1-deficient mice, i.e., IL-1beta(-/-), IL-1alpha(-/-), IL-1alpha/beta(-/-) (double knockout), and mice deficient in the naturally occurring inhibitor of IL-1, the IL-1 receptor antagonist (IL-1Ra). Tumors developed in all wild-type (WT) mice, whereas in IL-1beta-deficient mice, tumors developed slower and only in some of the mice. In IL-1Ra-deficient mice, tumor development was the most rapid. Tumor incidence was similar in WT and IL-1alpha-deficient mice. Histologic analyses revealed fibrotic structures forming a capsule surrounding droplets of the carcinogen in olive oil, resembling foreign body-like granulomas, which appeared 10 days after injection of 3-MCA and persisted until the development of local tumors. A sparse leukocyte infiltrate was found at the site of carcinogen injection in IL-1beta-deficient mice, whereas in IL-1Ra-deficient mice, a dense neutrophilic infiltrate was observed. Treatment of IL-1Ra-deficient mice with recombinant IL-1Ra but not with an inhibitor of tumor necrosis factor abrogated the early leukocytic infiltrate. The late leukocyte infiltrate (day 70), which was dominated by macrophages, was also apparent in WT and IL-1alpha-deficient mice, but was nearly absent in IL-1beta-deficient mice. Fibrosarcoma cell lines, established from 3-MCA-induced tumors from IL-1Ra-deficient mice, were more aggressive and metastatic than lines from WT mice; cell lines from IL-1-deficient mice were the least invasive. These observations show the crucial role of microenvironment-derived IL-1beta, rather than IL-1alpha, in chemical carcinogenesis and in determining the invasive potential of malignant cells.

Nrf2-deficient mice have an increased susceptibility to dextran sulfate sodium-induced colitis

Inflammatory bowel diseases, chronic inflammatory disorders, have been strongly linked with an increased risk of the development of colorectal cancer. Understanding the etiology of these diseases is pivotal for the improvement of currently available strategies to fight against inflammatory bowel disease, and more importantly, to prevent colorectal cancer. Nuclear factor-erythroid 2-related factor 2 (Nrf2) has been known to be a transcriptional factor which plays a crucial role in cytoprotection against inflammation, as well as oxidative and electrophilic stresses. The aim of this study is to investigate the role of Nrf2 in the regulation of dextran sulfate sodium (DSS)-induced experimental colitis in mice. Nrf2-deficient mice were found to be more susceptible to DSS-induced colitis as shown by the increased severity of colitis following 1 week of oral administration of 1% DSS. The increased severity of colitis in Nrf2(-/-) mice was found to be associated with decreased expression of antioxidant/phase II detoxifying enzymes including heme-oxygenase-1, NAD(P)H-quinone reductase-1, UDP-glucurosyltransferase 1A1, and glutathione S-transferase Mu-1. In addition, proinflammatory mediators/cytokines such as COX-2, inducible nitric oxide, interleukin 1beta, interleukin 6, and tumor necrosis factor alpha were significantly increased in the colonic tissues of Nrf2(-/-) mice compared with their wild-type (Nrf2+/+) counterparts. In summary, we show for the first time that mice lacking Nrf2 are more susceptible to DSS-induced colitis. Our data suggests that Nrf2 could play an important role in protecting intestinal integrity, through regulation of proinflammatory cytokines and induction of phase II detoxifying enzymes.

Identification of a novel competitive inhibitor of p38alpha MAPK by a human PBMC screen

The pro-inflammatory cytokines TNF-alpha and IL-1beta are two of the important mediators involved in the several chronic inflammatory diseases. We used the release of TNF-alpha and IL-1beta from lipopolysaccharide-stimulated human PBMC as inflammatory indexes to discover the potential anti-inflammatory candidates. Among near 500 chemical compounds, MT4 had the suppressive action on the release of TNF-alpha and IL-1beta in PBMC with IC50 values of 22 and 44 nM, respectively. After verified the MT4 inhibitory mechanism, the results revealed that p38alpha and p38beta MAPK activity was inhibited by MT4 with an IC50 value of 0.13 and 0.55 microM, respectively. Further characterization of enzyme kinetics showed the binding mode of MT4 was competitive with the ATP substrate-binding site of p38alpha MAPK.

Inflammation, atrophy, and gastric cancer

The association between chronic inflammation and cancer is now well established. This association has recently received renewed interest with the recognition that microbial pathogens can be responsible for the chronic inflammation observed in many cancers, particularly those originating in the gastrointestinal system. A prime example is Helicobacter pylori, which infects 50% of the world's population and is now known to be responsible for inducing chronic gastric inflammation that progresses to atrophy, metaplasia, dysplasia, and gastric cancer. This Review provides an overview of recent progress in elucidating the bacterial properties responsible for colonization of the stomach, persistence in the stomach, and triggering of inflammation, as well as the host factors that have a role in determining whether gastritis progresses to gastric cancer. We also discuss how the increased understanding of the relationship between inflammation and gastric cancer still leaves many questions unanswered regarding recommendations for prevention and treatment.

The participation of mesenchymal stem cells in tumor stroma formation and their application as targeted-gene delivery vehicles

Recent evidence suggests that mesenchymal stem cells (MSC) selectively proliferate to tumors and contribute to the formation of tumor-associated stroma. The biological rationale for tumor recruitment of MSC remains unclear but may represent an effort of the host to blunt tumor cell growth and improve survival. There is mounting experimental evidence that normal stromal cells can revert malignant cell behavior, and separate studies have demonstrated that stromal cells can enhance tumor progression after acquisition of tumor-like genetic lesions. Together, these observations support the rationale for modifying normal MSC to deliver therapeutic proteins directly into the tumor microenvironment. Modified MSC can produce high concentrations of antitumor proteins directly within the Tumor mass, which have been shown to blunt tumor growth kinetics in experimental animal model systems. In this chapter we will address the biological properties of MSC within the tumor microenvironment and discuss the potential use of MSC and other bone marrow-derived cell populations as delivery vehicles for antitumor proteins.

Chronic bacterial infection and inflammation incite reactive hyperplasia in a mouse model of chronic prostatitis

BACKGROUND

Chronic inflammation is postulated to contribute to prostate carcinogenesis. We developed a mouse model of chronic prostatitis to test whether infection-induced chronic inflammation would incite reactive changes in prostatic epithelium.

METHODS

Prostate tissues harvested from either phosphate-buffered saline (PBS) or E. coli-infected mice were evaluated for histological changes and immunostained for markers of oxidative stress and epithelial cell proliferation.

RESULTS

As compared to PBS-treated controls, mice infected with E. coli bacteria for 5 days showed foci of uniformly acute inflammation in the glandular lumen and a persistent inflammation at 12 weeks post-inoculation in the stroma. Prostatic glands showing varying degrees of atypical hyperplasia and dysplasia had stronger staining for oxidative DNA damage and increased epithelial cell proliferation than normal prostatic glands.

CONCLUSIONS

These data demonstrate that chronic inflammation induces reactive hyperplasia associated with oxidative stress injury and support the proposed linkage among inflammation, oxidative DNA damage, and prostate carcinogenesis.

Heterogeneity of mammary lesions represent molecular differences

Background

Human breast cancer is a heterogeneous disease, histopathologically, molecularly and phenotypically. The molecular basis of this heterogeneity is not well understood. We have used a mouse model of DCIS that consists of unique lines of mammary intraepithelial neoplasia (MIN) outgrowths, the premalignant lesion in the mouse that progress to invasive carcinoma, to understand the molecular changes that are characteristic to certain phenotypes. Each MIN-O line has distinguishable morphologies, metastatic potentials and estrogen dependencies.

Methods

We utilized oligonucleotide expression arrays and high resolution array comparative genomic hybridization (aCGH) to investigate whole genome expression patterns and whole genome aberrations in both the MIN-O and tumor from four different MIN-O lines that each have different phenotypes. From the whole genome analysis at 35 kb resolution, we found that chromosome 1, 2, 10, and 11 were frequently associated with whole chromosome gains in the MIN-Os. In particular, two MIN-O lines had the majority of the chromosome gains. Although we did not find any whole chromosome loss, we identified 3 recurring chromosome losses (2F1-2, 3E4, 17E2) and two chromosome copy number gains on chromosome 11. These interstitial deletions and duplications were verified with a custom made array designed to interrogate the specific regions at approximately 550 bp resolution.

Results

We demonstrated that expression and genomic changes are present in the early premalignant lesions and that these molecular profiles can be correlated to phenotype (metastasis and estrogen responsiveness). We also identified expression changes associated with genomic instability. Progression to invasive carcinoma was associated with few additional changes in gene expression and genomic organization. Therefore, in the MIN-O mice, early premalignant lesions have the major molecular and genetic changes required and these changes have important phenotypic significance. In contrast, the changes that occur in the transition to invasive carcinoma are subtle, with few consistent changes and no association with phenotype.

Conclusion

We propose that the early lesions carry the important genetic changes that reflect the major phenotypic information, while additional genetic changes that accumulate in the invasive carcinoma are less associated with the overall phenotype.

Dietary modulation of the multistage, multimechanisms of human carcinogenesis: effects on initiated stem cells and cell-cell communication

Diet can influence the risk to cancer in both negative and positive ways. Worldwide, more than 10 million persons develop cancer annually. Diet could prevent many cancers. Carcinogenesis is a multistage, multimechanism process, consisting of "initiation," "promotion," and "progression" phases. Although diet could affect each phase, an efficacious strategy for dietary chemoprevention would be intervention during the promotion phase. The tumor-promotion process requires sustained exposure to agents that stimulate the growth and inhibition of apoptosis of initiated cells in the absence of antipromoters. Chronic inflammation has been associated with the promotion process. The mechanism affecting the promotion process appears to be the inhibition of cell-cell communication between normal and initiated cells. Most, if not all, tumor-promoting agents and conditions, reversibly, inhibit cell-cell communication, whereas antipromoters, antioxidants, and anti-inflammatory agents have been shown to ameliorate the effects of tumor promoters on cell-cell communication. Additionally, adult stem cells are hypothesized to be the target cells for initiating the carcinogenic process. A new paradigm has been presented that postulates the first function of the carcinogenic process is to block the "mortalization" of a normal, "immortal" adult stem cell rather than the induction of "immortalization" of a normal mortal cell.

Hurdles to lymphocyte trafficking in the tumor microenvironment: implications for effective immunotherapy

An important consideration in the development of T cell-based cancer immunotherapy is that effector T cells must efficiently traffic to the tumor microenvironment in order to control malignant progression. T cell trafficking to target tissues is orchestrated by dynamic interactions between circulating lymphocytes and endothelial cells lining blood vessels. It is informative, in this regard, to compare and contrast the molecular mechanisms governing lymphocyte extravasation at distinct vascular sites: (1) high endothelial venules (HEV) of secondary lymphoid organs, which are portals for efficient trafficking of naive and central memory T lymphocytes; (2) non-activated endothelium of normal tissues that mediate relatively low basal levels of trafficking but are rapidly transformed into HEV-like vessels in response to local inflammatory stimuli; and (3) vessels within the intratumoral region and the surrounding peritumoral areas. These vessels can be distinguished by differential expression of hallmark trafficking molecules that function as molecular beacons directing lymphocyte migration across vascular barriers. This article reviews evidence that recruitment of effector T cells to the intratumoral microenvironment is impeded by sub-threshold expression of trafficking molecules on tumor microvessels. Emerging data support the thesis that when considered from the perspective of extravasation, vessels embedded within the intratumoral microenvironment of established tumors do not exhibit stereotypical characteristics of a chronic inflammatory state. A major challenge will be to develop therapeutic approaches to improve trafficking of effector T lymphocytes to tumor sites without skewing the balance in favor of a chronic inflammatory milieu that facilitates tumor maintenance and progression.

Circulating nucleic acids (CNAs) and cancer--a survey

It has been known for decades that it is possible to detect small amounts of extracellular nucleic acids in plasma and serum of healthy and diseased human beings. The unequivocal proof that part of these circulating nucleic acids (CNAs) is of tumor origin, initiated a surge of studies which confirmed and extended the original observations. In the past few years many experiments showed that tumor-associated alterations can be detected at the DNA and RNA level. At the DNA level the detection of point mutations, microsatellite alterations, chromosomal alterations, i.e. inversion and deletion, and hypermethylation of promoter sequences were demonstrated. At the RNA level the overexpression of tumor-associated genes was shown. These observations laid the foundation for the development of assays for an early detection of cancer as well as for other clinical means.

Cancer immunotherapy and preclinical studies: why we are not wasting our time with animal experiments

Experimental research on the immune response to transplanted tumors has led to pioneering discoveries that laid many of the foundations for the current field of immunology. Experimental research in oncology has proven that murine and human tumors have antigens that are truly cancer specific. This article discusses research investigating how can antigens on cancer cells be used to help eradicate cancer.

Mutual repression between steroid and xenobiotic receptor and NF-kappaB signaling pathways links xenobiotic metabolism and inflammation

While it has long been known that inflammation and infection reduce expression of hepatic cytochrome P450 (CYP) genes involved in xenobiotic metabolism and that exposure to xenobiotic chemicals can impair immune function, the molecular mechanisms underlying both of these phenomena have remained largely unknown. Here we show that activation of the nuclear steroid and xenobiotic receptor (SXR) by commonly used drugs in humans inhibits the activity of NF-kappaB, a key regulator of inflammation and the immune response. NF-kappaB target genes are upregulated and small bowel inflammation is significantly increased in mice lacking the SXR ortholog pregnane X receptor (PXR), thereby demonstrating a direct link between SXR and drug-mediated antagonism of NF-kappaB. Interestingly, NF-kappaB activation reciprocally inhibits SXR and its target genes whereas inhibition of NF-kappaB enhances SXR activity. This SXR/PXR-NF-kappaB axis provides a molecular explanation for the suppression of hepatic CYP mRNAs by inflammatory stimuli as well as the immunosuppressant effects of xenobiotics and SXR-responsive drugs. This mechanistic relationship has clinical consequences for individuals undergoing therapeutic exposure to the wide variety of drugs that are also SXR agonists.

Progress in chemoprevention drug development: the promise of molecular biomarkers for prevention of intraepithelial neoplasia and cancer--a plan to move forward

This article reviews progress in chemopreventive drug development, especially data and concepts that are new since the 2002 AACR report on treatment and prevention of intraepithelial neoplasia. Molecular biomarker expressions involved in mechanisms of carcinogenesis and genetic progression models of intraepithelial neoplasia are discussed and analyzed for how they can inform mechanism-based, molecularly targeted drug development as well as risk stratification, cohort selection, and end-point selection for clinical trials. We outline the concept of augmenting the risk, mechanistic, and disease data from histopathologic intraepithelial neoplasia assessments with molecular biomarker data. Updates of work in 10 clinical target organ sites include new data on molecular progression, significant completed trials, new agents of interest, and promising directions for future clinical studies. This overview concludes with strategies for accelerating chemopreventive drug development, such as integrating the best science into chemopreventive strategies and regulatory policy, providing incentives for industry to accelerate preventive drugs, fostering multisector cooperation in sharing clinical samples and data, and creating public-private partnerships to foster new regulatory policies and public education.

Green tea polyphenol EGCG suppresses cigarette smoke condensate-induced NF-kappaB activation in normal human bronchial epithelial cells

Cigarette smoke is a powerful inducer of inflammatory responses resulting in disruption of major cellular pathways with transcriptional and genomic alterations driving the cells towards carcinogenesis. Cell culture and animal model studies indicate that (-)-epigallocatechin-3-gallate (EGCG), the major polyphenol present in green tea, possesses potent anti-inflammatory and antiproliferative activity capable of selectively inhibiting cell growth and inducing apoptosis in cancer cells without adversely affecting normal cells. Here, we demonstrate that EGCG pretreatment (20-80 microM) of normal human bronchial epithelial cells (NHBE) resulted in significant inhibition of cigarette smoke condensate (CSC)-induced cell proliferation. Nuclear factor-kappaB (NF-kappaB) controls the transcription of genes involved in immune and inflammatory responses. In most cells, NF-kappaB prevents apoptosis by mediating cell survival signals. Pretreatment of NHBE cells with EGCG suppressed CSC-induced phosphorylation of IkappaBalpha, and activation and nuclear translocation of NF-kappaB/p65. NHBE cells transfected with a luciferase reporter plasmid containing an NF-kappaB-inducible promoter sequence showed an increased reporter activity after CSC exposure that was specifically inhibited by EGCG pretreatment. Immunoblot analysis showed that pretreatment of NHBE cells with EGCG resulted in a significant downregulation of NF-kappaB-regulated proteins cyclin D1, MMP-9, IL-8 and iNOS. EGCG pretreatment further inhibited CSC-induced phosphorylation of ERK1/2, JNK and p38 MAPKs and resulted in a decreased expression of PI3K, AKT and mTOR signaling molecules. Taken together, our data indicate that EGCG can suppress NF-kappaB activation as well as other pro-survival pathways such as PI3K/AKT/mTOR and MAPKs in NHBE cells, which may contribute to its ability to suppress inflammation, proliferation and angiogenesis induced by cigarette smoke.

Analysis of inflammation

In the past, inflammation has been associated with infections and with the immune system. But more recent evidence suggests that a much broader range of diseases have telltale markers for inflammation. Inflammation is the basic mechanism available for repair of tissue after an injury and consists of a cascade of cellular and microvascular reactions that serve to remove damaged and generate new tissue. The cascade includes elevated permeability in microvessels, attachment of circulating cells to the vessels in the vicinity of the injury site, migration of several cell types, cell apoptosis, and growth of new tissue and blood vessels. This review provides a summary of the major microvascular, cellular, and molecular mechanisms that regulate elements of the inflammatory cascade. The analysis is largely focused on the identification of the major participants, notably signaling and adhesion molecules, and their mode of action in the inflammatory cascade. We present a new hypothesis for the generation of inflammatory mediators in plasma that are derived from the digestive pancreatic enzymes responsible for digestion. The inflammatory cascade offers a large number of opportunities for development of quantitative models that describe various aspects of human diseases.

Cytokine mRNA expression in basal cell carcinoma

There is evidence that cytokines (CKs) play a significant role in the development and/or progression of skin cancer. The aim of the present study was to investigate the mRNA expression of tumour necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and IL-8 in biopsy specimens of basal cell carcinoma (BCC), and to compare the results with the mRNA levels of non-lesional skin of BCC patients and healthy subjects. Skin samples were obtained from 22 patients with BCC (lesional, non-lesional) and 25 healthy subjects (controls). Routine histology and real-time RT-PCR was performed. Histological examination revealed 12 nodular BCCs and 10 superficial BCCs. The mRNA levels of CKs observed in healthy controls did not significantly (P > 0.05) differ from non-lesional CK levels of BCCs patients. However, IL-6 and IL-8 levels of lesional skin were significantly (P < 0.05) higher than the CK levels observed in non-lesional skin and controls, respectively. mRNA expression of IL-6 and IL-8 showed a significant positive correlation (r = 0.51; P < 0.05). There was no significant (P > 0.05) difference between lesional mRNA levels of TNF-alpha and those levels observed in non-lesional skin and controls. The mRNA expression of CKs found in nodular and superficial BCCs did not significantly differ (P > 0.05). BCC is associated with a significant increase of IL-6 and IL-8 expression. We have shown for the first time that upregulation of IL-6 mRNA significantly correlates with IL-8 overexpresssion. In accordance with previous studies our data suggest a role for IL-6 and IL-8 in the development and/or progression of BCC, since mRNA expression of both CKs are significantly increased in tumour tissue.

Multiple molecular targets in cancer chemoprevention by curcumin

Carcinogenesis encompasses 3 closely associated stages: initiation, progression, and promotion. Phytochemicals are nonnutritive components of plants that are currently being studied in chemoprevention of various diseases for their pleiotropic effects and nontoxicity. Cancer chemoprevention involves the use of either natural or synthetic chemicals to prevent the initiation, promotion, or progression of cancer. Curcumin is the active constituent of turmeric, which is widely used as a spice in Indian cooking. It has been shown to possess anti-inflammatory, antioxidant, and antitumor properties. Curcumin has also been shown to be beneficial in all 3 stages of carcinogenesis. Much of its beneficial effect is found to be due to its inhibition of the transcription factor nuclear factor kappa B (NF-kappaB) and subsequent inhibition of proinflammatory pathways. This review summarizes the inhibition of NF-kappaB by curcumin and describes the recently identified molecular targets of curcumin. It is hoped that continued research will lead to development of curcumin as an anticancer agent.

TNF-alpha inhibits asbestos-induced cytotoxicity via a NF-kappaB-dependent pathway, a possible mechanism for asbestos-induced oncogenesis

Asbestos is the main cause of human malignant mesothelioma (MM). In vivo, macrophages phagocytize asbestos and, in response, release TNF-alpha and other cytokines that contribute to carcinogenesis through unknown mechanisms. In vitro, asbestos does not induce transformation of primary human mesothelial cells (HM); instead, asbestos is very cytotoxic to HM, causing extensive cell death. This finding raised an apparent paradox: How can asbestos cause MM if HM exposed to asbestos die? We found that asbestos induced the secretion of TNF-alpha and the expression of TNF-alpha receptor I in HM. Treatment of HM with TNF-alpha significantly reduced asbestos cytotoxicity. Through numerous technical approaches, including chemical inhibitors and small interfering RNA strategies, we demonstrate that, in HM, TNF-alpha activates NF-kappaB and that NF-kappaB activation leads to HM survival and resistance to the cytotoxic effects of asbestos. Our data show a critical role for TNF-alpha and NF-kappaB signaling in mediating HM responses to asbestos. TNF-alpha signaling through NF-kappaB-dependent mechanisms increases the percent of HM that survives asbestos exposure, thus increasing the pool of asbestos-damaged HM that are susceptible to malignant transformation. Cytogenetics supported this hypothesis, showing only rare, aberrant metaphases in HM exposed to asbestos and an increased mitotic rate with fewer irregular metaphases in HM exposed to both TNF-alpha and asbestos. Our findings provide a mechanistic rationale for the paradoxical inability of asbestos to transform HM in vitro, elucidate and underscore the role of TNF-alpha in asbestos pathogenesis in humans, and identify potential molecular targets for anti-MM prevention and therapy.

Sphingolipids as modulators of cancer cell death: potential therapeutic targets

Through modifications in the fine membrane structure, cell-cell or cell-matrix interactions, and/or modulation of intracellular signaling pathways, sphingolipids can affect the tumorigenic potential of numerous cell types. Whereas ceramide and its metabolites have been described as regulators of cell growth and apoptosis, these lipids as well as other sphingolipid molecules can modulate the ability of malignant cells to grow and resist anticancer treatments, and their susceptibility to non-apoptotic cell deaths. This review summarizes our current knowledge on the properties of sphingolipids in the regulation of cancer cell death and tumor development. It also provides an update on the potential perspectives of manipulating sphingolipid metabolism and using sphingolipid analogues in anticancer therapy.