

      Arriazu, Riánsares; Pozuelo, José M.; Henriques-Gil, Nuno; Perucho, Teresa; Martín, Rocío; Rodríguez, Rosario; Santamaría, Luis (2006-09)
      This work was directed to evaluate immunoexpression of markers for apoptosis, resistance to apoptosis, and cell proliferation, as well as estimates of nuclear size in ventral prostate of rats treated with cadmium chloride and cadmium+zinc chloride because a possible protective effect of zinc has been postulated. The following variables were studied: volume fraction (VF) of Bcl-2 immunostaining, percentage of cells immunoreactive to proliferating cell nuclear antigen (LIPCNA) and p53 (LIp53), numerical density of caspase-3 immunoreactive cells (NV caspase-3), and estimates of volume-weighted mean nuclear volume (upsilonV). The LIPCNA and VF of Bcl-2 were significantly increased in the treated animals. The dysplasias (independent of their origin) showed a significant increase of the LIp53, NV caspase-3, and upsilonV in comparison with normal acini from treated and control animals. It can be concluded that cell proliferation is enhanced in long-term cadmium-exposed rats, and exposure to zinc combined with cadmium had no effect on any of the variables studied when comparing with normal acini. The increase of nuclear upsilonV could indicate a more aggressive behavior for pretumoral lesions.
    • Incidence of cancer among female flight attendants: a meta-analysis.

      Tokumaru, Osamu; Haruki, Kosuke; Bacal, Kira; Katagiri, Tomomi; Yamamoto, Taisuke; Sakurai, Yutaka (2009-05-20)
      BACKGROUND: Airline flight personnel work in a unique environment with exposure to known or suspected carcinogens and mutagens including ionizing cosmic radiation. A meta-analysis was conducted to study whether the occupational exposure of female flight attendants (FA) increased their relative risk of cancer incidence. METHODS: A bibliographical computer search from 1966 to 2005 of cancer incidence cohort studies of female FA was performed. Combined relative risks (RRc) in cancer incidence were calculated by means of meta-analysis. RESULTS: RRc and 95% confidence interval (CI) for malignant melanoma and breast cancer in female FA were 2.13 (95% CI: 1.58-2.88) and 1.41 (1.22-1.62) (p < 0.0001). Excess risk was not significant for all-site cancer with RRc of 1.10 (0.99-1.21). CONCLUSIONS: The meta-analysis confirmed the significantly increased risks for malignant melanoma and breast cancer in female FA. Increased exposure to cosmic radiation during flight has been suggested as a potential occupational risk factor. Ultraviolet radiation exposure on board seems an unlikely occupational risk, but nonoccupational leisure time sun exposure is a possible risk factor. The etiology of the observed increase in incidence of some cancers remains controversial because assessment of possible confounders, especially nonoccupational exposure factors, has thus far been limited.
    • Increasing exposure levels cause an abrupt change in the absorption and metabolism of acutely inhaled benzo(a)pyrene in the isolated, ventilated, and perfused lung of the rat.

      Ewing, Per; Blomgren, Bo; Ryrfeldt, Ake; Gerde, Per (2006-06)
      The carcinogenic polycyclic aromatic hydrocarbons (PAHs) are active primarily at the site of entry to the body. Lung cancer following inhalation of PAH-containing aerosols such as tobacco smoke is one likely example. A suggested mechanism for this site preference is a slow passage of the highly lipophilic PAHs through the thicker epithelia of the conducting airways, accompanied by substantial local metabolism in airway epithelium. However, it is likely that the airway epithelium will become saturated with PAHs at surprisingly low exposure levels. The purpose of this research was to quantify the level of saturation for inhaled benzo(a)pyrene (BaP) in the isolated, perfused lung (IPL) of the rat. BaP was coated onto carrier particles of silica 3.5 microm diameter at three different levels. The DustGun aerosol generator was then used to deliver respectively 2.2, 36, and 8400 ng of BaP to the IPL with the carrier particles in less than 1 min. For 77 min after the exposure, single-pass perfusate was collected from the lungs. Lungs were then removed and, with the perfusate, analyzed for BaP and metabolites. Results show that the absorption and metabolism of inhaled BaP in the lungs was highly dose dependent. At low exposure levels absorption of BaP in the mucosa was proportional to the concentration in the air/blood barrier and proceeded with substantial local metabolism. At higher exposure levels the capacity of the epithelium to dissolve and metabolize BaP became saturated, and the absorption rate remained constant until crystalline BaP had dissolved, and the process proceeded with much smaller fractions of BaP metabolites produced in the mucosa. This phenomenon may explain the well-known difficulties of inducing lung cancer in laboratory animals with inhalants containing carcinogenic PAHs, where similar lifespan exposures are used as humans may experience but with much higher dose rates.

      Yu, Zhen; Mahadevan, Brinda; Lohr, Christiane V.; Fischer, Kay A.; Louderback, Mandy A.; Krueger, Sharon K.; Pereira, Clifford B.; Albershardt, Daniel J.; Baird, William M.; Bailey, George S.; et al. (2006-10)
      The fetus and neonate are sensitive targets for chemically induced carcinogenesis. Few studies have examined the risk/benefit of chemoprotective phytochemicals, given in the maternal diet, against transplacental carcinogenesis. In this study, B6129 SF1/J (AHR(b-1/d)) and 129Sv/ImJ (AHR(d/d)) mice were cross-bred. The polycyclic aromatic hydrocarbon, dibenzo[a,l]pyrene (DBP), was administered to pregnant mice (15 mg/kg, gavage) on gestation day 17, and 2000 p.p.m. indole-3-carbinol (I3C), a chemoprotective phytochemical from cruciferous vegetables, was fed to half of the mice from gestation day 9 until weaning. Offspring born to dams fed I3C exhibited markedly fewer mortalities (P < 0.0001). Maternal dietary exposure to I3C also significantly lowered lung tumor multiplicity (P = 0.035) in offspring surviving to 10 months of age. The I3C chemoprotection was independent of either maternal or fetal AHR genotype. The bioavailability of DBP to fetal target tissue was demonstrated by assessing DNA covalent adduction with a (33)P-post-labeling assay. The bioavailability of I3C was determined by dosing a subset of pregnant mice with [(14)C]-I3C. Addition of chemoprotective agents to the maternal diet during pregnancy and nursing may be an effective new approach in reducing the incidence of cancers in children and young adults.
    • Indoor radon and lung cancer risk in connecticut and utah.

      Sandler, Dale P.; Weinberg, Clarice R.; Shore, David L.; Archer, Victor E.; Stone, Mary Bishop; Lyon, Joseph L.; Rothney-Kozlak, Lynne; Shepherd, Marsha; Stolwijk, Jan A. J. (2006-04)
      Radon is a well-established cause of lung cancer in miners. Residents of homes with high levels of radon are potentially also at risk. Although most individual studies of indoor radon have failed to demonstrate significant risks, results have generally been consistent with estimates from studies of miners. We studied 1474 incident lung cancer cases aged 40-79 yr in Connecticut, Utah, and southern Idaho. Population controls (n = 1811) were identified by random telephone screening and from lists of Medicare recipients, and were selected to be similar to cases on age, gender, and smoking 10 yr before diagnosis/interview using randomized recruitment. Complete residential histories and information on known lung cancer risk factors were obtained by in-person and telephone interviews. Radon was measured on multiple levels of past and current homes using 12-mo alpha-track etch detectors. Missing data were imputed using mean radon concentrations for informative subgroups of controls. Average radon exposures were lower than anticipated, with median values of 23 Bq/m3 in Connecticut and 45 Bq/m3 in Utah/southern Idaho. Overall, there was little association between time-weighted average radon exposures 5 to 25 yr prior to diagnosis/interview and lung cancer risk. The excess relative risk (ERR) associated with a 100-Bq/m3 increase in radon level was 0.002 (95% CI -0.21, 0.21) in the overall population, 0.134 (95% CI -0.23, 0.50) in Connecticut, and -0.112 (95% CI -0.34, 0.11) in Utah/Idaho. ERRs were higher for some subgroups less prone to misclassification, but there was no group with a statistically significant linear increase in risk. While results were consistent with the estimates from studies of miners, this study provides no evidence of an increased risk for lung cancer at the exposure levels observed.

      Smith-Roe, Stephanie L.; Löhr, Christiane V.; Bildfell, Robert J.; Fischer, Kay A.; Hegan, Denise Campisi; Glazer, Peter M.; Buermeyer, Andrew B. (2006-11-28)
      Disruption of the DNA mismatch repair (MMR) pathway results in elevated mutation rates, inappropriate survival of cells bearing DNA damage, and increased cancer risk. Relatively little is known about the impact of environmentally relevant carcinogens on cancer risk in individuals with MMR-deficiency. We evaluated the effect of MMR status (Mlh1(+/+) versus Mlh1(-/-)) on the carcinogenic potential of the cooked-meat mutagen, 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP) in mice. PhIP exposure did not obviously increase lymphoma or small intestinal tumorigenesis in either Mlh1-deficient or -proficient mice. In contrast, the frequency of aberrant crypt foci (ACF), a preneoplastic biomarker for colon tumorigenesis, was increased by PhIP, and the increase due to PhIP was significantly greater in Mlh1(-/-) versus wild-type littermates. This apparent heightened susceptibility to induction of ACF parallels the previously reported hypermutability of Mlh1-deficient mice to PhIP and is consistent with the hypothesis that MMR-deficiency would increase the likelihood of PhIP-induced carcinogenic mutations. Further evaluation of the risk that consumption of heterocyclic amines may impart to MMR-deficient individuals therefore is warranted.
    • Inflammation, a key event in cancer development.

      Lu, Haitian; Ouyang, Weiming; Huang, Chuanshu (2006-04)
      Several recent studies have identified nuclear factor-kappaB as a key modulator in driving inflammation to cancers. Besides this transcription factor, essential in regulating inflammation and cancer development, an inflammatory microenvironment inhabiting various inflammatory cells and a network of signaling molecules are also indispensable for the malignant progression of transformed cells, which is attributed to the mutagenic predisposition of persistent infection-fighting agents at sites of chronic inflammation. As a subverted host response to inflammation-induced tumors, the inflammatory cells and regulators may facilitate angiogenesis and promote the growth, invasion, and metastasis of tumor cells. Thus far, research regarding inflammation-associated cancer development has focused on cytokines and chemokines as well as their downstream targets in linking inflammation and cancer. Moreover, other proteins with extensive roles in inflammation and cancer, such as signal transducers and activators of transcription, Nrf2, and nuclear factor of activated T cells, are also proposed to be promising targets for future studies. The elucidation of their specific effects and interactions will accelerate the development of novel therapeutic interventions against cancer development triggered by inflammation.
    • Influence of cadmium on murine thymocytes: potentiation of apoptosis and oxidative stress.

      Pathak, Neelima; Khandelwal, Shashi (2006-08-20)
      Cadmium (Cd) is a well-known environmental carcinogen and a potent immunotoxicant. It induces thymocyte apoptosis in vitro. However, the mode of action is unclear. In this study, we examined the effect of Cd (10, 25 and 50microM) on mitochondrial membrane potential and caspase-3 as well as oxidative stress markers in murine thymocytes. The cadmium induced apoptosis occurred in a concentration and time dependent manner. The early markers of apoptosis-loss in mitochondrial membrane potential and caspase-3 activation were evident as early as 1.5h by 50microM Cd. Enhanced reactive oxygen species (ROS) generation and glutathione (GSH) depletion were observed at 60min, prior to the lowering of mitochondrial membrane potential. The Cd induced DNA damage as depicted by internucleosomal fragmentation on agarose and histone associated mono- and oligonucleosomes detection by ELISA, corrobated with the apoptotic DNA (sub-G(1) population) and total apoptotic cells by Annexin V binding assay. The number of cells in sub-G(1) population increased to 66% at 50microM Cd concentration and the distribution of early and late apoptotic cells was 47% and 15%, respectively. Addition of N-acetylcysteine and pyrrolidine dithiocarbamate (thiol antioxidants) to the Cd treated cells, lowered the sub-G(1) population, inhibited the ROS generation and raised the GSH levels. Buthionine sulfoximine (GSH depletor) on the other hand, enhanced both the ROS production and the sub-G(1) fraction. These results clearly demonstrate the apoptogenic potential of Cd in murine thymocytes, following mitochondrial membrane depolarization, caspase activation and ROS and GSH acting as critical mediators.
    • Inhibition of benzo[a]pyrene-activating enzymes and DNA binding in human bronchial epithelial BEAS-2B cells by methoxylated flavonoids.

      Tsuji, Petra A.; Walle, Thomas (2006-08)
      Cigarette smoking is a major risk factor in lung carcinogenesis via carcinogens such as polycyclic aromatic hydrocarbons (PAHs) and nitrosamines. In this study, we used benzo[a]pyrene (BaP) as the classic PAH compound and BEAS-2B cells, a model of normal human bronchial epithelial cells, to investigate whether 5,7-dimethoxyflavone (5,7-DMF) and 3',4'-DMF compared with resveratrol (RV) have chemopreventive properties in this cancer. Exposure of BEAS-2B cells to [(3)H]BaP (1 microM) showed increasing binding to DNA up to 72 h of exposure, about 20-fold higher than that at 0.5 h exposure. BaP exposure also increased both CYP1A1/1B1 and microsomal epoxide hydrolase (mEH) enzyme activities with a maximum 10-fold increase at 48 h. BaP induced CYP1A1 protein and mRNA levels maximally after 48 h. In contrast, although CYP1B1 mRNA was rapidly induced, its protein expression showed a very poor response. Simultaneous treatment with BaP and 5,7-DMF, 3',4'-DMF or RV for 48 h inhibited BaP-DNA binding by > or =75%, with 3',4'-DMF being the most effective. 5,7-DMF affected CYP1A1 mRNA levels only modestly, whereas 3',4'-DMF was a potent inhibitor. The catalytic activity of CYP1A1/1B1 was reduced over 95% after exposure to 5,7-DMF, 3',4'-DMF or RV, most effectively by 3',4'-DMF. BaP-induced mEH activity was not affected by treatment with 5,7-DMF, but was significantly inhibited by 3',4'-DMF. In contrast, mEH activity was notably increased by RV. Most importantly, western blotting showed all three polyphenols dramatically reducing BaP-induced CYP1A1 protein expression. Both 5,7-DMF and 3',4'-DMF demonstrated very high, about 40-fold, accumulation in BEAS-2B cells. In summary, BaP exposure results in a high level of DNA binding in BEAS-2B cells, which is mainly mediated by induction of CYP1A1 protein, just as in the human lung. Two methoxylated dietary flavonoids with highly specific effects on BaP bioactivation block this DNA binding and CYP1A1 protein expression as effectively as RV, thus making them potential chemopreventive agents for BaP-induced lung carcinogenesis.

      Siddiqui, Imtiaz A.; Zaman, Najia; Aziz, Moammir H.; Reagan-Shaw, Shannon R.; Sarfaraz, Sami; Adhami, Vaqar M.; Ahmad, Nihal; Raisuddin, Sheikh; Mukhtar, Hasan (2006-04)
      Cancer of the prostate gland (CaP), the most common invasive malignancy and a major cause of cancer related deaths in male population in the USA, is an ideal candidate disease for chemoprevention because it is typically detected in elderly population with a relatively slower rate of growth and progression. Many dietary phytochemicals are showing promising chemopreventive effects, at-least in pre-clinical models of CaP. Our published data in cell culture and animal studies, supported by the work from other laboratories, as well as epidemiological observations and case-control studies, suggest that polyphenols present in green tea possess CaP chemopreventive and possibly therapeutic effects. This present study was designed to compare CaP cancer chemopreventive effects of green tea polyphenols (GTP), water extract of black tea, and their major constituents epigallocatechin-3-gallate and theaflavins, respectively, in athymic nude mice implanted with androgen-sensitive human CaP CWR22Rnu1 cells. Our data demonstrated that the treatment with all the tea ingredients resulted in (i) significant inhibition in growth of implanted prostate tumors, (ii) reduction in the level of serum prostate specific antigen, (iii) induction of apoptosis accompanied with upregulation in Bax and decrease in Bcl-2 proteins, and (iv) decrease in the levels of VEGF protein. Furthermore, we also found that GTP (0.01 or 0.05% w/v; given after establishment of CWR22Rnu1 tumor) causes a significant regression of tumors suggesting therapeutic effects of GTP at human achievable concentrations.
    • Inhibition of hepatocarcinogenesis by the deletion of the p50 subunit of NF-kappaB in mice administered the peroxisome proliferator Wy-14,643.

      Glauert, Howard P.; Eyigor, Aysegul; Tharappel, Job C.; Cooper, Simon; Lee, Eun Y.; Spear, Brett T. (2006-04)
      Wy-14,643 (WY) is a hypolipidemic drug that induces hepatic peroxisome proliferation and tumors in rodents. We previously showed that peroxisome proliferators increase NF-kappaB DNA binding activity in rats, mice, and hepatoma cell lines, and that mice deficient in the p50 subunit of NF-kappaB had much lower cell proliferation in response to the peroxisome proliferator ciprofibrate. In this study we examined the promotion of hepatocarcinogenesis by WY in the p50 knockout (-/-) mice. The p50 -/- and wild type mice were first administered diethylnitrosamine (DEN) as an initiating agent. Mice were then fed a control diet or a diet containing 0.05% WY for 38 weeks. Wild-type mice receiving DEN only developed a low incidence of tumors, and the majority of wild-type mice receiving both DEN and WY developed tumors. However, no tumors were seen in any of the p50 -/- mice. Cell proliferation and apoptosis were measured in hepatocytes by BrdU labeling and the TUNEL assay, respectively. Treatment with DEN + WY increased both cell proliferation and apoptosis in both the wild-type and p50 -/- mice; DEN treatment alone has no effect. In the DEN/WY-treated mice, cell proliferation and apoptosis were slightly lower in the p50 -/- mice than in the wild-type mice. These data demonstrate that NF-kappaB is involved in the promotion of hepatic tumors by the peroxisome proliferator WY; however, the difference in tumor incidence could not be attributed to alterations in either cell proliferation or apoptosis.
    • Instability of expanded simple tandem repeats is induced in cell culture by a variety of agents: N-Nitroso-N-ethylurea, benzo(a)pyrene, etoposide and okadaic acid.

      Polyzos, Aris; Parfett, Craig; Healy, Caroline; Douglas, George R.; Yauk, Carole L. (2006-06-25)
      Expanded simple tandem repeat (ESTR) sequences have proven useful biomarkers to detect genotoxicity in vivo. Their high sensitivity has been used to assess environmentally relevant doses of mutagens such as ionizing radiation, DNA alkylating agents and airborne particulate pollution, for germline mutations in mouse assays. The mutagenic response involves size alteration of these ESTR loci induced by agents causing a variety of cellular damage. The mechanistic aspects of this induced instability remain unclear and have not been studied in detail. Mechanistic knowledge is important to help understand the relevance of increased ESTR mutation frequencies. In this study, we applied a murine cell culture system to examine induced response to four agents exhibiting different modes of toxic action including: N-nitroso-N-ethylurea (ENU), benzo(a)pyrene (BaP), okadaic acid and etoposide at slightly sub-toxic levels. We used single-molecule-polymerase chain reaction (SM-PCR) to assess the relative mutant frequency after 4-week chemical treatments at the Ms6-hm ESTR sequence of cultured C3H/10T1/2 cells (a mouse embryonic cell line). Increased mutation was observed with both 0.64 mM ENU (1.95-fold increase, P<0.0001), 1 microM benzo(a)pyrene (1.87-fold increase, P=0.0006) and 3 nM etoposide (1.89-fold increase, P=0.0003). The putative ESTR mutagen okadaic acid (1.27-fold increase, P=0.2289), administered at 0.5 nM, did not affect the C3H/10T1/2 Ms6-hm locus. Therefore, agents inducing small and bulky adducts, and indirectly causing strand breaks through inhibition of topoisomerase, caused similar induction of instability at an ESTR locus at matched toxicities. As size spectra for induced mutations were identical, the data indicate that although these chemicals exhibit distinct modes of action, a similar indirect process is influencing ESTR instability. In contrast, a potent tumour promoter that is a kinase inhibitor does not contribute to induced ESTR instability in cell culture.
    • International studies of prenatal exposure to polycyclic aromatic hydrocarbons and fetal growth.

      Choi, Hyunok; Jedrychowski, Wieslaw; Spengler, John; Camann, David E.; Whyatt, Robin M.; Rauh, Virginia; Tsai, Wei-Yann; Perera, Frederica P. (2006-11)
      OBJECTIVES: Polycyclic aromatic hydrocarbons (PAHs) are ubiquitously distributed human mutagens and carcinogens. However, lack of adequate air monitoring data has limited understanding of the effects of airborne PAHs on fetal growth. To address this gap in knowledge, we examined the association between prenatal exposure to airborne PAHs and birth weight, birth length, and birth head circumference, respectively, in Krakow, Poland, and New York City (NYC). METHODS: The parallel prospective cohort studies enrolled nonsmoking, healthy, and nonoccupationally exposed women and their newborns. Personal air monitoring of pregnant women was conducted over 48 hr. To control for maternal environmental tobacco smoke (ETS) exposure, we excluded those with umbilical cord plasma cotinine concentrations > 25 ng/mL. Mean cord plasma cotinine concentrations in both ethnic groups were
    • Lack of promoting effects of phenobarbital at low dose on diethylnitrosamine-induced hepatocarcinogenesis in TGF-alpha transgenic mice.

      Puatanachokchai, Rawiwan; Kakuni, Masakazu; Wanibuchi, Hideki; Kinoshita, Anna; Kang, Jin Seok; Salim, Elsayed I.; Morimura, Keiichirou; Tamano, Seiko; Merlino, Glenn T.; Fukushima, Shoji (2009-03-16)
      Phenobarbital (PB), a rodent non-genotoxic carcinogen, showed hormesis, biphasic effects on rat liver carcinogenesis. To test the hypothesis that the hormesis earlier observed for PB induced hepatocarcinogenesis might also exist in the TGF-alpha transgenic mice model, one which is highly susceptible to carcinogenesis, the carcinogenic or promotion effects of a wide range of phenobarbital (PB) concentrations were investigated. Two weeks after a single i.p. dose of 5 mg /kg bw of diethylnitrosamine (DEN) to 15 day old mice, animals were treated with diet containing PB at doses of 0, 2, 15 or 500 ppm. The incidence and multiplicity of tumors, including hepatocellular adenomas and carcinomas, were significantly increased by the high dose of PB, but no significant difference among the groups receiving 2 and 15 ppm for liver tumors when compared to DEN alone group. The proliferating cell nuclear antigen indices for liver tumors and surrounding hepatocytes in high dose PB treated mice were significantly increased, but no change was noted at the lower doses. The total cytochrome P450 content in the liver was also elevated by 500 ppm of PB, while hepatic 8-OHdG levels demonstrated no significant change. In conclusion, PB at high dose enhances DEN-induced hepatocarcinogenesis in TGF-alpha transgenic mice, but low doses lack any significant effects. One possible mechanism of phenobarbital carcinogenicity might be influenced by cytochrome P450 system exhibiting a strong promoting activity for liver of mice.
    • Levels of 1-hydroxypyrene and other monohydroxy polycyclic aromatic hydrocarbons in children: a study based on U.S. reference range values.

      Huang, Wenlin; Caudill, Samuel P.; Grainger, James; Needham, Larry L.; Patterson, Donald G. (2006-05-05)
      Urine samples collected in 1999 and 2000 as part of the National Health and Nutrition Examination Survey (NHANES) were analyzed for 14 monohydroxy polycyclic aromatic hydrocarbons (PAH, metabolites of 7 PAH compounds) and for the first time reference range values were calculated for these metabolites in the U.S. population. The purpose of this paper is to explore differences in these PAH metabolites between children (6-11 years old), adolescents, and adults. More than 99% of the urine samples contained a detectable amount of 1-hydroxypyrene (1-OHpyrene), a metabolite of pyrene. We found that children in the youngest age group (6-11 years) had a geometric mean level (creatinine corrected data) 30% higher than children and adults in the other age groups, but no statistical differences existed between the two genders and among different racial groups. Smokers and persons exposed to environmental tobacco smoke (ETS) in 12-19-year-old group and the 20-year-and-older group had higher levels of urinary 1-OHpyrene by a factor of 2-3 than non-smokers in the corresponding age group. Measurements of 3-hydroxyphenanthrene also suggested increased levels in children and in smokers. These results may indicate that young children are at a greater risk for PAH exposure, or that they absorb, distribute, metabolize, or eliminate PAH differently than adults.
    • Lifelong persistence of AML associated MLL partial tandem duplications (MLL-PTD) in healthy adults.

      Basecke, Jorg; Podleschny, Martina; Clemens, Robert; Schnittger, Susanne; Viereck, Volker; Trumper, Lorenz; Griesinger, Frank (2006-09)
      AML-associated MLL-PTD contribute to leukemogenesis by a gain of function and confer an unfavorable prognosis. Like other leukemia associated aberrations they are also present in healthy adults. To delineate the leukemogenic mechanism we tracked down MLL-PTD in normal hematopoiesis and investigated cord blood samples. MLL-PTD were observed in 56/60 (93%) of all cord bloods. In contrast to AML, the transcript frequency in cord blood was four log scales lower as determined by real-time PCR. The CD34+ progenitor cell, CD33+ myeloid, CD19+ B-lymphoid and CD3+ T-lymphoid subfractions were positive. The ubiquitous presence of MLL-PTD in cord blood implicates a lifelong exposure, not an accumulation during lifetime. Since also present in the stem cell subfraction, these factors seem not to be major determinants in MLL-PTD leukemogenesis.
    • Lung cancer risk among former uranium miners of the WISMUT Company in Germany.

      Brüske-Hohlfeld, Irene; Rosario, Angelika Schaffrath; Wölke, Gabriele; Heinrich, Joachim; Kreuzer, Michaela; Kreienbrock, Lothar; Wichmann, H-Erich (2006-03)
      After 1946, the WISMUT Company developed the third-largest uranium-mining province in the world in the German Democratic Republic. METHODS: A case-control study among former WISMUT miners was conducted to investigate the lung cancer risk in relation to attained age, time since exposure, exposure duration, and exposure rate. It consisted of 505 patients with lung cancer and 1,073 controls matched to cases according to the year of birth. The cumulative exposure to radon and radon decay products was calculated as the sum of yearly exposures and expressed in Working Level Months (WLM). Cases had a mean cumulative exposure of 552 WLM compared to 420 WLM in controls. RESULTS: There was a statistically significant increase in lung cancer risk for cumulative exposures above 800 WLM. Under the assumption of a linear risk model, there was a significant increase in the relative risk of 0.10 per 100 WLM after adjusting for smoking and asbestos exposure. For current smokers the increase in relative risk was lower (0.05 per 100 WLM), whereas it was higher (0.20 per 100 WLM) among nonsmokers and longtime ex-smokers. After correcting in a sensitivity analysis for the fact that the controls of this study had a higher average exposure than the population of WISMUT workers they were recruited from, the adjusted ERR increased to 0.24 per 100 WLM. Lung cancer risk declined with time since exposure, except for exposures received 45 or more years ago. No inverse dose rate effect was observed.

      González, Carlos A.; Jakszyn, Paula; Pera, Guillem; Agudo, Antonio; Bingham, Sheila; Palli, Domenico; Ferrari, Pietro; Boeing, Heiner; del Giudice, Giuseppe; Plebani, Mario; et al. (2006-03-01)
    • Metabolic profile in workers occupationally exposed to arsenic: role of GST polymorphisms.

      Marcos, Ricardo; Martínez, Valeria; Hernández, Alba; Creus, Amadeu; Sekaran, Chandra; Tokunaga, Hiroshi; Quinteros, Domingo (2006-03)
      Arsenic is a well-known human carcinogen with a ubiquitous distribution in the natural environment. Chronic exposure to inorganic arsenic involves a biotransformation process that leds to the main excretion of organic methylated metabolites, such as monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), as well as the parental inorganic species. Interindividual variation in arsenic metabolism has been extensively reported, and polymorphisms in genes involved in such process could be related to changes in the arsenic excretion profile and the response to chronic exposures. Our analysis of the metabolic profiles in three groups of workers exposed to different arsenic exposure levels showed high amounts of inorganic arsenic and MMA in the most-exposed workers versus the least-exposed workers, in whom high amounts of DMA were observed. With respect to the role of different genetic polymorphisms in the glutathione S-transferase (GST) genes in the modulation of the urinary profiles, for the overall population only a tendency was just observed between GSTM1 null and MMA excretion as well as between GSTP1 val/val and DMA excretion.
    • Modifying effect of dietary sesaminol glucosides on the formation of azoxymethane-induced premalignant lesions of rat colon.

      Sheng, HongQiang; Hirose, Yoshinobu; Hata, Kazuya; Zheng, Qiao; Kuno, Toshiya; Asano, Nami; Yamada, Yasuhiro; Hara, Akira; Osawa, Toshihiko; Mori, Hideki (2007-02-08)
      Sesame, which has been reported to have preventive effects against various disordered conditions, contains small quantities of lignans and several precursors to them such as sesaminol glucosides (SG). The lignans have the potent antioxidative activity and are suggested to have chemopreventive property. In the present study, we evaluated the modulating effect of SG on the development of colon precancerous lesions, aberrant crypt foci (ACF) and beta-catenin-accumulated crypts (BCAC), in the azoxymethane (AOM)-induced short-term model using male F344 rats. Dietary SG (500 ppm) significantly decreased the incidence of AOM-induced ACF when compared to the control (P<0.01). The incidences of AOM-induced BCAC in the SG-treated groups (250 or 500 ppm) were also significantly lower than that of the control group (P<0.01). Interestingly, administration of 500 ppm SG clearly decreased serum triglyceride level and mRNA expression of intestinal fatty acid-binding protein in the colonic mucosa, as compared to the control. These findings indicate that dietary SG inhibits AOM-induced carcinogenesis and suggest SG as a possible chemopreventive agent.