• Biomarkers of environmental contaminants in field population of green mussel (Perna viridis) from Karnataka-Kerala coast (South West coast of India).

      Krishnakumar, P.K.; Sasikumar, Geetha; Bhat, G.S.; Asokan, D.P.K. (2006-05)
      The green mussel Perna viridis was sampled from relatively clean and contaminated sites along the Kartanata-Kerala coast (south west coast of India) to study the tissue concentration of trace metals and biological responses to stress (biomarkers) such as sister chromatid exchange (SCE), chromosomal aberration, micronucleus (MN) test, hemic neoplasia (HN), Chromotest (Ames test) and comet assay. In general, mean tissue concentrations of toxic trace metals collected from 25 sampling sites were found to be below the World Health Organisation (WHO) permissible concentration given for seafood. The digestive gland extract of mussels from all 25 sampling sites showed negative reaction for mutagenic activity (Ames test) in the absence of metabolic activation. Very low levels of chromosomal aberration, SCE, MN, HN and comet cells were observed in mussels collected from both the urban associated and relatively clean sites. This study seems to indicate that that the coastal waters of Karnataka and Kerala are minimally contaminated with genotoxic and carcinogenic chemicals.
    • Biomarkers of exposure, effect, and susceptibility in workers exposed to nitrotoluenes.

      Sabbioni, Gabriele; Jones, Christopher R.; Sepai, Ovnair; Hirvonen, Ari; Norppa, Hannu; Järventaus, Hilkka; Glatt, Hansruedi; Pomplun, Doreen; Yan, Huifang; Brooks, Lance R.; et al. (2006-03)
      Nitrotoluenes, such as 2-nitrotoluene, 2,4-dinitrotoluene (24DNT), and 26DNT, are carcinogenic in animal experiments. Humans are exposed to such chemicals in the workplace and in the environment. It is therefore important to develop methods to biomonitor people exposed to nitrotoluenes to prevent the potential harmful effects. For the present study, workers exposed to high levels of these chemicals were investigated. The external dose (air levels), the internal dose (urine metabolites), the biologically effective dose [hemoglobin (Hb) adducts and urine mutagenicity], and biological effects (chromosomal aberrations and health effects) were determined. Individual susceptibility was assessed by determining genetic polymorphisms of enzymes assumed to function in nitrotoluene metabolism, namely glutathione S-transferases (GSTM1, GSTT1, GSTP1), N-acetyltransferases (NAT1, NAT2), and sulfotransferases (SULT1A1, SULT1A2). The levels of urinary metabolites did not correlate with the air levels. The urinary mutagenicity levels determined in a subset of workers correlated with the levels of a benzylalcohol metabolite of DNT. The Hb-adducts correlated with the urine metabolites but not with the air levels. The frequency of chromosomal aberrations (gaps included) was increased (P < 0.05) in the exposed workers in comparison with a group of factory controls and correlated with the level of 24DNT Hb-adducts in young subjects (<31 years). The GSTM1-null genotype was significantly more prevalent in the controls than in the exposed group, which probably reflected an elevated susceptibility of the GSTM1-null genotype to adverse health effects of DNT exposure, such as nausea (odds ratio, 8.8; 95% confidence interval, 2.4-32.2). A statistically significant effect was seen for SULT1A2 genotype on a 24DNT Hb-adduct; GSTP1 genotype on a 2,4,6-trinitrotoluene Hb-adduct; and SULT1A1, SULT1A2, NAT1, GSTT1, and GSTP1 genotypes on chromosomal aberrations in the exposed workers.
    • Black tea polyphenols protect against 7,12-dimethylbenz[a]anthracene-induced hamster buccal pouch carcinogenesis.

      Letchoumy, P. Vidjaya; Chandra Mohan, K. V. P.; Kumaraguruparan, R.; Hara, Y.; Nagini, S. (2006)
      Dietary chemoprevention has emerged as a cost-effective approach for cancer control. We evaluated the chemopreventive effects of black tea polyphenols (Polyphenon-B) administration during the preinitiation phase of 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis. The expression of proliferating cell nuclear antigen (PCNA) in the buccal pouch and the concentration of lipid peroxides, protein carbonyl, and the antioxidant status in the buccal pouch, liver and erythrocytes were used as biomarkers of chemoprevention. All the hamsters painted with DMBA alone for 14 weeks developed buccal pouch carcinomas associated with increased expression of PCNA, diminished lipid and protein oxidation, and enhanced antioxidant status. In the liver and erythrocytes of tumor-bearing animals, enhanced oxidation of lipids and proteins was accompanied by compromised antioxidant defenses. Dietary administration of Polyphenon-B effectively suppressed DMBA-induced HBP carcinogenesis as revealed by decreased incidence of tumours and PCNA expression. In addition, Polyphenon-B modulated lipid and protein oxidation and enhanced the antioxidant status in the pouch, liver, and erythrocytes. We suggest that Polyphenon-B exerts its chemopreventive effects by inhibiting cell proliferation in the target tissue and modulating the oxidant-antioxidant status in the target as well as in host tissues.
    • Bladder cancer mortality and private well use in New England: an ecological study.

      Ayotte, Joseph D.; Baris, Dalsu; Cantor, Kenneth P.; Colt, Joanne; Robinson, Gilpin R.; Lubin, Jay H.; Karagas, Margaret; Hoover, Robert N.; Fraumeni, Joseph F.; Silverman, Debra T. (2006-02)
      STUDY OBJECTIVE: To investigate the possible relation between bladder cancer mortality among white men and women and private water use in New England, USA, where rates have been persistently raised and use of private water supplies (wells) common. DESIGN: Ecological study relating age adjusted cancer mortality rates for white men and women during 1985-1999 and proportion of persons using private water supplies in 1970. After regressing mortality rates on population density, Pearson correlation coefficients were computed between residual rates and the proportion of the population using private water supplies, using the state economic area as the unit of calculation. Calculations were conducted within each of 10 US regions. SETTING: The 504 state economic areas of the contiguous United States. PARTICIPANTS: Mortality analysis of 11 cancer sites, with the focus on bladder cancer. MAIN RESULTS: After adjusting for the effect of population density, there was a statistically significant positive correlation between residual bladder cancer mortality rates and private water supply use among both men and women in New England (men, r = 0.42; women, r = 0.48) and New York/New Jersey (men, r = 0.49; women, r = 0.62). CONCLUSIONS: Use of well water from private sources, or a close correlate, may be an explanatory variable for the excess bladder cancer mortality in New England. Analytical studies are underway to clarify the relation between suspected water contaminants, particularly arsenic, and raised bladder cancer rates in northern New England.
    • Brassica vegetable consumption reduces urinary F2-isoprostane levels independent of micronutrient intake.

      Fowke, Jay H.; Morrow, Jason D.; Motley, Saundra; Bostick, Roberd M.; Ness, Reid M (2006-10)
      Isothiocyanates and indoles (e.g. indole-3-carbinol) from Brassica vegetables (e.g. broccoli) induce Phase I and Phase II enzymes responsible for the oxidation, reduction and metabolism of endogenous and exogenous carcinogens. Brassica vegetables also contain micronutrients that may provide additional DNA protection from reactive oxygen species. This randomized crossover trial (n = 20) compares the effects of a Brassica Vegetable (BV) intervention against a Micronutrient and Fiber Supplementation (M+F) intervention on urinary F2-isoprostane levels (F2-iP), a stable biomarker of systemic oxidative stress. Brassica intake was monitored by repeated 24 h recalls, urinary ITC levels and questionnaire. Urinary F2-iP levels were measured by mass spectrometry from first-morning urine samples collected at Baseline and after each intervention, and change in natural log transformed urinary F2-iP levels were analyzed using repeated measures regression. Brassica consumption increased from 2 grams/day (g/d) during the Baseline or M+F intervention periods to 218 g/d during the BV intervention, whereas exposure to most antioxidant vitamins and minerals was greatest during the M+F intervention. F2-iP levels significantly decreased by 22.0 or 21.8% during the BV intervention compared with Baseline or the M+F intervention (P = 0.05, P = 0.05, respectively). Urinary F2-iP levels did not significantly differ between Baseline and the M+F intervention (difference = 0.2%; P = 0.98). Brassica intake has been associated with reduced risk of colon, lung, bladder, breast, prostate and other cancers. Our results suggest that Brassica consumption reduces systemic oxidative stress independent of the vitamin and mineral content of these vegetables.
    • Cancer chemopreventive and anti-inflammatory activities of chemically modified guar gum.

      Gamal-Eldeen, Amira M.; Amer, Hassan; Helmy, Wafaa A. (2006-07-10)
      Guar gum (G) is a simple characterized branched polysaccharide, which is frequently used in food industries. We prepared the gum C-glycosylated derivative (GG), and its sulphated derivative (SGG), aiming to characterize their cancer chemopreventive, and anti-inflammatory properties. Estimation of cancer chemopreventive activity, specifically anti-initiation, including the modulation of carcinogen metabolism and the antioxidant capacity, revealed that GG was a potent anti-initiator, where it inhibited not only the carcinogen activator enzyme, cytochrome P450 1A (CYP1A), but also induced the carcinogen detoxification enzymes glutathione-S-transferases (GSTs), while SGG inhibited both CYP1A and GSTs. SGG was an effective radical scavenger than GG against hydroxyl, peroxyl, and superoxide anion radicals. GG and SGG were found to modulate the macrophage functions into an anti-inflammatory pattern. Thus, both enhanced the macrophage proliferation and phagocytosis of fluorescein isothiocyanate (FITC)-zymosan; however, they also inhibited strongly the nitric oxide generation and tumor necrosis factor-alpha secretion in lipopolysaccharide (LPS)-stimulated RAW macrophage 264.7. Unexpectedly, both GG and SGG dramatically inhibited the binding affinity of FITC-LPS to RAW 264.7, as indicated by flow cytometry analysis. GG and SGG exhibited a significant anti-proliferative activity against human hepatocellular carcinoma cells (Hep G2), and only SGG was specifically cytotoxic for human breast carcinoma cells (MCF-7), but neither was significantly cytotoxic for human lymphoblastic leukemia cells (1301). SGG led to a major disturbance in cell cycle phases of Hep G2 cells as indicated by concomitant arrest in S- and G2/M-phases, a disturbance that was associated with an induced cell death as a result of necrosis, but not apoptosis in both GG- and SGG-treated cells. Taken together, the modified gums could be used as an alternative of G in health food industries to provide cancer prevention in risk populations.
    • Cancer survivorship--genetic susceptibility and second primary cancers: research strategies and recommendations.

      Travis, Lois B.; Rabkin, Charles S.; Brown, Linda Morris; Allan, James M.; Alter, Blanche P.; Ambrosone, Christine B.; Begg, Colin B.; Caporaso, Neil; Chanock, Stephen; DeMichele, Angela; et al. (2006-01-04)
      Cancer survivors constitute 3.5% of the United States population, but second primary malignancies among this high-risk group now account for 16% of all cancer incidence. Although few data currently exist regarding the molecular mechanisms for second primary cancers and other late outcomes after cancer treatment, the careful measurement and documentation of potentially carcinogenic treatments (chemotherapy and radiotherapy) provide a unique platform for in vivo research on gene-environment interactions in human carcinogenesis. We review research priorities identified during a National Cancer Institute (NCI)-sponsored workshop entitled "Cancer Survivorship--Genetic Susceptibility and Second Primary Cancers." These priorities include 1) development of a national research infrastructure for studies of cancer survivorship; 2) creation of a coordinated system for biospecimen collection; 3) development of new technology, bioinformatics, and biomarkers; 4) design of new epidemiologic methods; and 5) development of evidence-based clinical practice guidelines. Many of the infrastructure resources and design strategies that would facilitate research in this area also provide a foundation for the study of other important nonneoplastic late effects of treatment and psychosocial concerns among cancer survivors. These research areas warrant high priority to promote NCI's goal of eliminating pain and suffering related to cancer.
    • Carbohydrate digestibility predicts colon carcinogenesis in azoxymethane-treated rats.

      Jacobsen, Helene; Poulsen, Morten; Dragsted, Lars Ove; Ravn-Haren, Gitte; Meyer, Otto; Lindecrona, Rikke Hvid (2006)
      The purpose of this study was to compare the effect of carbohydrate structure and digestibility on azoxymethane (AOM)-induced colon carcinogenesis. Five groups of male Fischer 344 rats each comprising 30 animals were injected with AOM and fed a high-fat diet with 15% of various carbohydrates. The carbohydrate sources used were sucrose, cornstarch (a linear starch, reference group), potato starch (a branched starch), a short-chained oligofructose (Raftilose), and a long-chained inulin-type fructan (Raftiline). An interim sacrifice was performed after 9 wk to investigate markers of carbohydrate digestibility, including caecal fermentation (caecum weight and pH) and glucose and lipid metabolism [glucose, fructoseamine, HbA1c, triglycerides, and insulin-like growth factor (IGF) 1]. In addition potential early predictors of carcinogenicity [cell proliferation and aberrant crypt foci (ACF)] at 9 wk and their correlation to colon cancer risk after 32 wk were investigated. Tumor incidence was significantly reduced in animals fed oligofructose, and the number of tumors per animal was significantly reduced in animals fed inulin and oligofructose at 32 wk after AOM induction compared to the reference group fed sucrose. Increased caecum weight and decreased caecal pH were seen in groups fed oligofructose, inulin, and potato starch. Plasma triglyceride was decreased in rats fed oligofructose and inulin. Cell proliferation was increased in the proximal colon of rats fed sucrose, oligofructose, and inulin, and the number of cells per crypt decreased in rats fed oligofructose and inulin. The total number of ACF's was unaffected by treatment, and the size and multiplicity of ACF was unrelated to tumor development. It was concluded that less digestible carbohydrates with an early effect on caecum fermentation and plasma triglyceride decreased subsequent tumor incidence and multiplicity. This was unrelated to ACF, cell proliferation, and other markers of glucose and lipid metabolism.
    • CD40 ligation protects bronchial epithelium against oxidant-induced caspase-independent cell death.

      Merendino, Anna M.; Bucchieri, Fabio; Gagliardo, Rosalia; Daryadel, Arezoo; Pompeo, Flora; Chiappara, Giuseppina; Santagata, Roberta; Bellia, Vincenzo; David, Sabrina; Farina, Felicia; et al. (2006-08)
      CD40 and its ligand regulate pleiotropic biological responses, including cell proliferation, differentiation, and apoptosis. In many inflammatory lung diseases, tissue damage by environmental or endogenous oxidants plays a major role in disease pathogenesis. As the epithelial barrier is a major target for these oxidants, we postulated that CD40, the expression of which is increased in asthma, plays a role in the regulation of apoptosis of bronchial epithelial cells exposed to oxidants. Using 16HBE 14o- cells exposed to oxidant stress, we found that ligation of CD40 (induced by G28-5 monoclonal antibodies) enhanced cell survival and increased the number of cells in G2/M (interphase between DNA synthesis and mitosis) of the cell cycle. This was associated with NF-kappaB and activator protein-1 activation and increased expression of the inhibitor of apoptosis, c-IAP1. However, oxidant stress-induced apoptosis was found to be caspase- and calpain-independent implicating CD40 ligation as a regulator of caspase-independent cell death. This was confirmed by the demonstration that CD40 ligation prevented mitochondrial release and nuclear translocation of apoptosis inducing factor. In conclusion, we demonstrate a novel role for CD40 as a regulator of epithelial cell survival against oxidant stress. Furthermore, we have identified, for the first time, an endogenous inhibitory pathway of caspase-independent cell death.
    • The challenge resulting from positive and negative effects of sunlight: how much solar UV exposure is appropriate to balance between risks of vitamin D deficiency and skin cancer?

      Reichrath, Jörg (2006-09)
      There is no doubt that solar ultraviolet (UV) exposure is the most important environmental risk factor for the development of non-melanoma skin cancer. Therefore, sun protection is of particular importance to prevent these malignancies, especially in risk groups. However, 90% of all requisite vitamin D has to be formed in the skin through the action of the sun-a serious problem, for a connection between vitamin D deficiency and a broad variety of independent diseases including various types of cancer, bone diseases, autoimmune diseases, hypertension and cardiovascular disease has now been clearly indicated in a large number of epidemiologic and laboratory studies. An important link that improved our understanding of these new findings was the discovery that the biologically active vitamin D metabolite 1,25(OH)(2)D is not exclusively produced in the kidney, but in many other tissues such as prostate, colon, skin and osteoblasts. Extra-renally produced 1,25(OH)(2)D is now considered to be an autocrine or paracrine hormone, regulating various cellular functions including cell growth. We and others have shown that strict sun protection causes vitamin D deficiency in risk groups. In the light of new scientific findings that convincingly demonstrate an association of vitamin D deficiency with a variety of severe diseases including various cancers, the detection and treatment of vitamin D deficiency in sun-deprived risk groups is of high importance. It has to be emphasized that in groups that are at high risk of developing vitamin D deficiency (e.g., nursing home residents or patients under immunosuppressive therapy), vitamin D status has to be monitored. Vitamin D deficiency should be treated, e.g., by giving vitamin D orally. Dermatologists and other clinicians have to recognize that there is convincing evidence that the protective effect of less intense solar UV radiation outweighs its mutagenic effects. Although further work is necessary to define an adequate vitamin D status and adequate guidelines for solar UV exposure, it is at present mandatory that public health campaigns and recommendations of dermatologists on sun protection consider these facts. Well-balanced recommendations on sun protection have to ensure an adequate vitamin D status, thereby protecting people against adverse effects of strict sun protection without significantly increasing the risk of developing UV-induced skin cancer.
    • Challenges identifying genetic determinants of pediatric cancers--the childhood leukemia experience.

      Sinnett, Daniel; Labuda, Damian; Krajinovic, Maja (2006)
      Pediatric cancers affect approximately 1 in every 500 children before the age of 15. Little is known about the etiology of this heterogeneous group of diseases despite the fact they constitute the major cause of death by disease among this population. Because of its relatively high prevalence, most of the work done in pediatric oncogenetics has been focused on leukemias, particularly acute lymphoblastic leukemia (ALL). Although it is now well accepted that genetic variation plays a significant role in determining individual's cancer susceptibility, few studies have explored genetic susceptibility to childhood leukemia with respect to common polymorphisms. The biochemical and genetic mechanisms contributing to cancer susceptibility are numerous and can be grouped into broad categories: (1) cellular growth and differentiation, (2) DNA replication and repair, (3) metabolism of carcinogens (4) apoptosis, (5) oxidative stress response and (6) cell cycle. To evaluate whether candidate genes in these pathways are involved in childhood leukemogenesis, we conducted case-control studies. We showed that leukemogenesis in children may be associated with DNA variants in some of these genes and that the combination of genotypes seems to be more predictive of risk than either of them independently. We also observed that, at least at some loci, the parental genetics might be important in predicting the risk of cancer in this pediatric model of a complex disease. Taken together, these results indicate that the investigation of a single enzyme and/or a single genotype might not be sufficient to explain the etiology of childhood leukemia because of the complexity of the environment and that of the inter-individual variability in cancer susceptibility.
    • Characterization of 67 kD laminin receptor, a protein whose gene is overexpressed on treatment of cells with anti-benzo[a]pyrene-7,8-diol-9,10-epoxide.

      An, She-Juan; Chen, Jia-Kun; Chen, Hua-jie; Chang, Wei; Jiang, Yi-Guo; Wei, Qing-Yi; Chen, Xue-Min (2006-04)
      The molecular mechanisms potentially related to tumorigenesis induced by anti-benzo[a]pyrene-7,8-diol-9,10-epoxide (anti-BPDE) were investigated by suppression subtractive hybridization of the human bronchial epithelial cells (16HBE) carcinoma induced by BPDE-transformed 16HBE cells (16HBE-C). The 67 kD laminin receptor gene (67LR1) is one of the screened overexpressed genes in 16HBE-C cells when compared with 16HBE. In order to understand the main functions of 67LR1 gene, we amplified the full length of 67LR1 gene using reverse transcription-polymerase chain reaction (RT-PCR) method. The amplified gene products were inserted into pcDNA 3.1 Directional TOPO expression vector. We then transfected 16HBE cells with this vector and derived stable transfected 16HBE cell lines containing the 67LR1 gene by using lipofectin and G418 selection protocols. The expression products of transfected genes were analyzed by semiquantitative RT-PCR. Soft agar growth assay was carried out to identify the malignant features of 67LR1 gene. The stable transfected cell lines can form colonies in soft agar. Further, the transfected cells showed morphological changes compared to the control cells, such as the obvious pseudopods. These data suggest that the 67LR1 gene may be related to malignant transformation induced by the anti-BPDE. The 67LR1 protein may be related to the directionality of cell movement.
    • Chemoprevention of mouse urinary bladder carcinogenesis by fermented brown rice and rice bran.

      Kuno, Toshiya; Hirose, Yoshinobu; Yamada, Yasuhiro; Hata, Kazuya; Qiang, Sheng Hong; Asano, Nami; Oyama, Takeru; Zhi, Huilan; Iwasaki, Teruaki; Kobayashi, Hiroshi; et al. (2006-03)
      Fermented brown rice by Aspergillus oryzae (FBRA) has been shown to be a potent anti-carcinogenic compound. Here, we investigated the modifying effects of dietary feeding with a naturally occurring anti-oxidant FBRA on N-butyl-N-(4-hydroxybutyl)-nitrosamine (OH-BBN)-induced urinary bladder carcinogenesis in male ICR mice. Five-week-old male ICR mice were divided into 7 groups, and groups 1-5 were given OH-BBN (500 ppm) in drinking water for 6 weeks starting at 7 weeks of age. Groups 2 and 3 were fed the diet containing 5% and 10% FBRA during the initiation phase, respectively, whereas groups 4 and 5 were fed these diets during the post-initiation phase. Group 6 was given the diet containing 10% FBRA throughout the experiment, and group 7 was kept on the basal diet alone and served as an untreated control. At the end of the study (week 32), the incidences of simple hyperplasia, dysplasia and carcinoma in the bladders of group 1 (OH-BBN alone) were 92%, 49% and 38%, respectively. Those of group 5 (64%, 23% and 10%) and the incidence of carcinoma of group 4 (17%) was significantly less than that of group 1. Furthermore, the multiplicity of simple hyperplasia and carcinoma of group 5 was significantly less than that of group 1. Post-initiation exposure of 10% FBRA significantly decreased the number/nucleus of silver-stained nucleolar organizer region proteins (AgNORs), an index of cell proliferation, in the non-lesional transitional epithelium when compared to that of the control. Our results indicate that FBRA exerts chemopreventive effects against chemically induced urinary bladder carcinogenesis through anti-proliferative mechanisms. FBRA could be a promising chemopreventive agent for human urinary bladder cancer.
    • Chemoprevention of photocarcinogenesis by selected dietary botanicals.

      Baliga, Manjeshwar S.; Katiyar, Santosh K. (2006-02)
      Epidemiological, clinical and laboratory studies have implicated solar ultraviolet (UV) radiation as a tumor initiator, tumor promoter and complete carcinogen, and their excessive exposure can lead to the development of various skin disorders including melanoma and nonmelanoma skin cancers. Sunscreens are useful, but their protection is not adequate to prevent the risk of UV-induced skin cancer. It may be because of inadequate use, incomplete spectral protection and toxicity. Therefore new chemopreventive methods are necessary to protect the skin from photodamaging effects of solar UV radiation. Chemoprevention refers to the use of agents that can inhibit, reverse or retard the process of skin carcinogenesis. In recent years, considerable interest has been focused on identifying naturally occurring botanicals, specifically dietary, for the prevention of photocarcinogenesis. A wide variety of botanicals, mostly dietary flavonoids or phenolic substances, have been reported to possess substantial anticarcinogenic and antimutagenic activities because of their antioxidant and antiinflammatory properties. This review summarizes chemopreventive effects of some selected botanicals, such as apigenin, curcumin, grape seed proanthocyanidins, resveratrol, silymarin, and green tea polyphenols, against photocarcinogenesis in in vitro and in vivo systems. Attention has also been focused on highlighting the mechanism of chemopreventive action of these dietary botanicals. We suggest that in addition to the use of these botanicals as dietary supplements for the protection of photocarcinogenesis, these botanicals may favorably supplement sunscreens protection and may provide additional antiphotocarcinogenic protection including the protection against other skin disorders caused by solar UV radiation.
    • Chemopreventive effects of dietary flaxseed on colon tumor development.

      Bommareddy, Ajay; Arasada, Bhanu L.; Mathees, Duane P.; Dwivedi, Chandradhar (2006)
      Fatty acid composition of dietary fat plays a vital role in colon tumor development in animal models. Fats containing omega-6 fatty acids (e.g., corn oil) enhanced and omega-3 fatty acids (e.g., flaxseed oil) reduced chemically induced colon tumor development in rats. Lignans have also been shown to prevent colon tumor development in experimental animals. The objective of this investigation is to study the effects of dietary flaxseed meal, a source of both omega-3 fatty acid and lignans, on colon tumor development and compare them with the effects of dietary corn meal. Male Fischer rats, two groups of 24 each, were assigned to the AIN-93M diet supplemented with either 15% corn meal or 15% flaxseed meal, respectively. Carcinogenesis was initiated with subcutaneous injections of azoxymethane (15 mg/kg) once a week for 3 consecutive wk. After 35 wk of initiation, rats were anesthetized with ether. Blood was collected by cardiac puncture, and rats were sacrificed. The gastrointestinal tract was isolated. The site, size, and number of tumors were recorded. The fatty acid analysis of the collected serum and colon samples was performed. Expression of cyclooxygenase (COX)-1 and COX-2 was performed by Western blot method. Lignan levels in serum and colon samples were assayed. Colon tumor incidence, multiplicity, and size were found to be 82.6% and 29.4%; 1.3 and 0.3; and 44.4 and 5.3 mm(2) in corn and flaxseed meal groups, respectively. Colon and serum samples of the corn meal group showed higher levels of omega-6 fatty acid levels whereas the flaxseed meal group exhibited higher levels of omega-3 fatty acids. COX-1 and COX-2 expression in the flaxseed group was significantly lower (P < 0.05) as compared to the corn group. Dietary flaxseed meal containing high levels of omega-3 fatty acids and lignans is effective in preventing colon tumor development when compared with dietary corn meal possibly by increasing omega-3 fatty acid levels and decreasing COX-1 and COX-2 levels.
    • Chemopreventive effects of rofecoxib and folic acid on gastric carcinogenesis induced by N-methyl-N'-nitro-N-nitrosoguanidine in rats.

      Fei, Su Juan; Xiao, Shu Dong; Peng, Yan Shen; Chen, Xiao Yu; Shi, Yao (2006)
      OBJECTIVES: Epidemiological and experimental studies indicate that non-steroidal anti-inflammatory drugs (NSAIDs) are chemopreventive agents of gastrointestinal cancers, but few studies on gastric cancer have been carried out. A decrease in folic acid supplement and subsequent DNA hypomethylation are related to gastrointestinal cancers, and it has been shown that high-dose folic acid may interfere with gastric carcinogenesis in dogs. The objective of this study was to investigate the effects of rofecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, and folic acid on the chemoprevention of gastric cancer induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Wistar rats, and to evaluate the cell proliferation of gastric mucosa in different experimental groups. METHODS: Eighty male Wistar rats were randomly divided into five groups (16 rats in each group). In the control group, the rats were given pure water and basal diet. In the MNNG group, the rats received MNNG in drinking water (100 mg/L) and basal diet. In the MNNG + low-dose rofecoxib group, the rats were given MNNG and rofecoxib 5 mg/kg per day with basal diet. In the MNNG + high-dose rofecoxib group, the rats were given MNNG and rofecoxib 15 mg/kg per day with basal diet. In the MNNG + folic acid group, the rats were given MNNG and folic acid 5 mg/kg per day with basal diet. The experiment was terminated at 50 weeks, and all rats were killed. Blood samples of 3 mL were obtained for measurement of serum folic acid concentrations in the control group, the MNNG group and the MNNG + folic acid group by using chemiluminescent method. The stomach was removed from all rats for histopathological examination and immunohistochemical study. Proliferating cell nuclear antigen (PCNA) expression in gastric epithelial cells was also determined. RESULTS: In the MNNG group, five of 11 rats (45.5%) developed gastric cancer, while in all other four groups no gastric cancer was found (P < 0.05). The positivity rate of PCNA expression in the cancerous tissues was significantly higher than that in the non-cancerous tissues (80.0%vs 14.1%, P < 0.05). The positivity rate of PCNA expression in the gastric mucosal cells of the MNNG group was significantly higher than that in the other four groups. The mean serum folic acid concentration of rats was significantly higher in the MNNG + folic acid group (193.70 +/- 60.73 ng/mL) than those in the control group (84.21 +/- 25.26 ng/mL) and the MNNG group (72.27 +/- 16.70 ng/mL, P < 0.05). It was shown that both low- and high-dose rofecoxib as well as folic acid interfered with the development of gastric cancer induced by MNNG in Wistar rats. CONCLUSIONS: The results indicate that rofecoxib as well as folic acid interferes with gastric carcinogenesis induced by MNNG in Wistar rats, and the suppression of gastric cell proliferation may play a crucial role in the chemoprevention of gastric cancer by rofecoxib and folic acid. The higher serum folic acid concentration of rats may play an important role in the prevention of gastric cancer.
    • Clove (Syzygium aromaticum L.), a potential chemopreventive agent for lung cancer.

      Banerjee, Sarmistha; Panda, Chinmay Kr; Das, Sukta; Department of Cancer Chemoprevention, Chittarajan National Cancer Institute, 37, S.P. Mukherjee Road, Kolkata 700026, India. (2006-08)
      Spices and flavoring plants part rich in supposedly health-promoting phytochemicals are currently receiving much attention as a possible source of cancer chemopreventive compounds. Clove, the sun-dried unopened flower bud from the plant Syzygium aromaticum L. is a commonly used spice and food flavor. In the present work we assess the chemopreventive potential of aqueous infusion of clove during benzo[a]pyrene (BP)-induced lung carcinogenesis in strain A mice. Incidence of hyperplasia, dysplasia and carcinoma in situ evident in the carcinogen control group on the 8th, 17th and 26th weeks, respectively, were effectively reduced after treatment with clove infusion. Significant reduction in the number of proliferating cells and an increased number of apoptotic cells was also noted in these BP-induced lung lesions following clove treatment. Western blotting analysis revealed that clove infusion upregulates the expression of pro-apoptotic proteins p53 and Bax, and downregulates the expression of anti-apoptotic protein Bcl-2 in the precancerous stages. Expression of caspase 3 and its activation by clove infusion were evident from a very early stage of carcinogenesis (eighth week). Clove infusion was also found to downregulate the expression of some growth-promoting proteins, viz, COX-2, cMyc, Hras. The observations signify the chemopreventive potential of clove in view of its apoptogenic and anti-proliferative properties.
    • A combined analysis of North American case-control studies of residential radon and lung cancer.

      Krewski, Daniel; Lubin, Jay H.; Zielinski, Jan M.; Alavanja, Michael; Catalan, Vanessa S.; Field, R. William; Klotz, Judith B.; Letourneau, Ernest G.; Lynch, Charles F.; Lyon, Joseph L.; et al. (2006-04)
      Cohort studies have consistently shown underground miners exposed to high levels of radon to be at excess risk of lung cancer, and extrapolations based on those results indicate that residential radon may be responsible for nearly 10-15% of all lung cancer deaths per year in the United States. However, case-control studies of residential radon and lung cancer have provided ambiguous evidence of radon lung cancer risks. Regardless, alpha-particle emissions from the short-lived radioactive radon decay products can damage cellular DNA. The possibility that a demonstrated lung carcinogen may be present in large numbers of homes raises a serious public health concern. Thus, a systematic analysis of pooled data from all North American residential radon studies was undertaken to provide a more direct characterization of the public health risk posed by prolonged radon exposure. To evaluate the risk associated with prolonged residential radon exposure, a combined analysis of the primary data from seven large scale case-control studies of residential radon and lung cancer risk was conducted. The combined data set included a total of 4081 cases and 5281 controls, representing the largest aggregation of data on residential radon and lung cancer conducted to date. Residential radon concentrations were determined primarily by a-track detectors placed in the living areas of homes of the study subjects in order to obtain an integrated 1-yr average radon concentration in indoor air. Conditional likelihood regression was used to estimate the excess risk of lung cancer due to residential radon exposure, with adjustment for attained age, sex, study, smoking factors, residential mobility, and completeness of radon measurements. Although the main analyses were based on the combined data set as a whole, we also considered subsets of the data considered to have more accurate radon dosimetry. This included a subset of the data involving 3662 cases and 4966 controls with a-track radon measurements within the exposure time window (ETW) 5-30 yr prior to the index date considered previously by Krewski et al. (2005). Additional restrictions focused on subjects for which a greater proportion of the ETW was covered by measured rather than imputed radon concentrations, and on subjects who occupied at most two residences. The estimated odds ratio (OR) of lung cancer generally increased with radon concentration. The OR trend was consistent with linearity (p = .10), and the excess OR (EOR) was 0.10 per Bq/m3 with 95% confidence limits (-0.01, 0.26). For the subset of the data considered previously by Krewski et al. (2005), the EOR was 0.11 (0.00, 0.28). Further limiting subjects based on our criteria (residential stability and completeness of radon monitoring) expected to improve radon dosimetry led to increased estimates of the EOR. For example, for subjects who had resided in only one or two houses in the 5-30 ETW and who had a-track radon measurements for at least 20 yr of this 25-yr period, the EOR was 0.18 (0.02, 0.43) per 100 Bq/m3. Both estimates are compatible with the EOR of 0.12 (0.02, 0.25) per 100 Bq/m3 predicted by downward extrapolation of the miner data. Collectively, these results provide direct evidence of an association between residential radon and lung cancer risk, a finding predicted by extrapolation of results from occupational studies of radon-exposed underground miners.
    • Combined analysis of r-1,t-2,3,c-4-tetrahydroxy-1,2,3,4-tetrahydrophenanthrene and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol in smokers' plasma.

      Carmella, Steven G.; Yoder, Andrea; Hecht, Stephen S. (2006-08)
      Polycyclic aromatic hydrocarbons (PAH) and tobacco-specific nitrosamines, such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), are widely accepted to be two important types of lung carcinogens in cigarette smoke. In this study, we have developed a method to estimate individual uptake of these compounds by quantifying r-1,t-2,3,c-4-tetrahydroxy-1,2,3,4-tetrahydrophenanthrene (PheT) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) in 1 mL of smokers' plasma. PheT and NNAL are biomarkers of PAH and NNK uptake, respectively. [D10]PheT and [pyridine-D4]NNAL were added to plasma as internal standards. The plasma was treated with beta-glucuronidase to release any conjugated PheT and NNAL. The analytes were enriched by solid-phase extraction on a mixed mode cation exchange cartridge and the PheT fraction was further purified by high-performance liquid chromatography. The appropriate fractions were analyzed by gas chromatography-negative ion chemical ionization-mass spectrometry for PheT and liquid chromatography-electrospray ionization-mass spectrometry for NNAL. The method was sensitive (limits of quantitation: PheT, 13 fmol/mL; NNAL, 3 fmol/mL), accurate, and precise. Levels of PheT and NNAL in plasma from 16 smokers averaged 95 +/- 71 and 36 +/- 21 fmol/mL, respectively, which are approximately 1% to 2% of the amounts found in urine. This method should be useful in molecular epidemiology studies of carcinogen uptake and lung cancer in smokers.
    • Combined antioxidant (beta-carotene, alpha-tocopherol and ascorbic acid) supplementation increases the levels of lung retinoic acid and inhibits the activation of mitogen-activated protein kinase in the ferret lung cancer model.

      Kim, Yuri; Chongviriyaphan, Nalinee; Liu, Chun; Russell, Robert M.; Wang, Xiang-Dong (2006-07)
      Interactions among beta-carotene (BC), alpha-tocopherol (AT) and ascorbic acid (AA) led to the hypothesis that using a combination of these antioxidants could be more beneficial than using a single antioxidant alone, particularly against smoke-related lung cancer. In this investigation, we have conducted an animal study to determine whether combined BC, AT and AA supplementation (AOX) protects against 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung carcinogenesis in smoke-exposed (SM) ferrets. Ferrets were treated for 6 months in the following four groups: (i) control, (ii) SM + NNK, (iii) AOX and (iv) SM + NNK + AOX. Results showed that the combined AOX supplementation (i) prevented the SM + NNK-decreased lung concentrations of retinoic acid (RA) and BC; (ii) inhibited the SM + NNK-induced phosphorylation of Jun N-terminal kinase (JNK), extracellular-signal-regulated protein kinase (ERK) and proliferating cellular nuclear antigen proteins in the lungs of ferrets; and (iii) blocked the SM + NNK-induced up-regulation of total p53 and Bax proteins, as well as phosphorylated p53 in the lungs of ferrets. In addition, there were no lesions observed in the lung tissue of ferrets in the control and/or the AOX groups after 6 months of intervention, but combined AOX supplementation resulted in a trend toward lower incidence of both preneoplastic lung lesions and lung tumor formation in SM + NNK + AOX group of ferrets, as compared with the SM + NNK group alone. These data indicate that combined AOX supplementation could be a useful chemopreventive strategy against lung carcinogenesis through maintaining normal tissue levels of RA and inhibiting the activation of mitogen-activated protein kinase pathways, cell proliferation and phosphorylation of p53.