Administração do extrato de garcinia brasiliensis e modulação do ambiente tumoral em modelo de carcinogênese pulmonar / Administration of garcinia brasiliensis extract and modulation of the tumor environment in a model of pulmonary carcinogenesis / Administración de extracto de garcinia brasiliensis y modulación del ambiente tumoral en un modelo de carcinogénesis pulmonar

Introdução: O benzopireno é um dos principais hidrocarbonetos aromáticos policíclicos presentes no ambiente e com alta capacidade carcinogênica, sendo, portanto, usado em modelos in vivo de carcinogênese pulmonar. Investigações têm mostrado o envolvimento dos mastócitos na modulação do ambiente tumoral e que os fármacos anti-inflamatórios podem reduzir a incidência de câncer de pulmão. Entre as possibilidades terapêuticas estão os fitoterápicos. O extrato de Garcinia brasiliensis, conhecido popularmente como bacupari, mostra propriedades anti-inflamatórias e antitumorais, mas ainda pouco estudado em modelos animais. Objetivos: Avaliar os efeitos da administração do extrato alcoólico de G. brasiliensis em modelo de carcinogênese induzida por benzopireno. Material e Método: O extrato bruto foi obtido por percolação com o uso de 20 g das folhas secas e trituradas de G. brasiliensis e 100 ml de etanol a 70%, por 24h. Ratos Wistar foram divididos em 3 grupos, um controle sem indução ou tratamento, um induzido pelo benzopireno (100 mg/kg, diluído em DMSO e administrado intraperitonealmente, uma única aplicação) e um grupo tratado por gavagem (1 ml) com extrato de bacupari a 4% (3x/semana, por 7 semanas, a partir da 15o semana da indução. Os animais de todos os grupos foram eutanasiados após 21 semanas para coleta dos pulmões que foram processados para análises histopatológicas (HE) e histoquímicas (Azul de Toluidina e Azul de Alcian Safranina) para quantificação dos mastócitos. Resultados: Os resultados das análises histopatológicas mostraram desorganização do parênquima pulmonar, aumento de tecido linfático associado aos brônquios, grande influxo de células inflamatórias e regiões de displasia. Pela coloração de azul de toluidina os mastócitos foram identificados na forma intacta e desgranulada (em processo de ativação). Na coloração conjunta Azul de Alcian e Safranina, os mastócitos corados em azul representam as fases iniciais do processo de maturação, enquanto os corados em vermelho estão maduros. A quantificações evidenciaram maior quantidade de mastócitos desgranulados, azul de Alcian e mistos (corados pelo Azul de Alcian e Safranina) nos grupos tratados com o extrato. Conclusão: Os dados indicam que o ambiente tumoral nos animais tratados mostra maior modulação dos mastócitos, com mais células jovens e ativadas. Mais análises serão realizadas para verificar se a ativação dos mastócitos promovida pelo tratamento com o extrato ocorre para contenção ou promoção do processo tumoral.(AU)

Introduction: Benzopyrene is one of the main polycyclic aromatic hydrocarbons present in the environment and with a high carcinogenic capacity, being, therefore, used in in vivo models of lung carcinogenesis. Investigations have shown the involvement of mast cells in modulating the tumor environment and that anti-inflammatory drugs can reduce the incidence of lung cancer. Among the therapeutic possibilities are herbal medicines. Garcinia brasiliensis extract, popularly known as bacupari, shows anti-inflammatory and antitumor properties, but still little studied in animal models. Objectives: To evaluate the effects of the administration of the alcoholic extract of G. brasiliensis in a model of carcinogenesis induced by benzopyrene. Material and Methods: The crude extract was obtained by percolation using 20 g of dried and crushed leaves of G. brasiliensis and 100 ml of 70% ethanol for 24 hours. Wistar rats were divided into 3 groups, a control without induction or treatment, one induced by benzopyrene (100 mg/kg, diluted in DMSO and administered intraperitoneally, a single application) and a group treated by gavage (1 ml) with bacupari extract. at 4%...(AU)

Introducción: El benzopireno es uno de los principales hidrocarburos aromáticos policíclicos presentes en el ambiente y tiene una elevada capacidad carcinogénica, por lo que se utiliza en modelos in vivo de carcinogénesis pulmonar. Las investigaciones han demostrado la implicación de los mastocitos en la modulación del entorno tumoral y que los fármacos antiinflamatorios pueden reducir la incidencia del cáncer de pulmón. Entre las posibilidades terapéuticas están las fitoterapias. El extracto de Garcinia brasiliensis, conocido popularmente como bacupari, muestra propiedades antiinflamatorias y antitumorales, pero todavía está sido poco estudiado en modelos animales. Objetivos: Evaluar los efectos de la administración del extracto alcohólico de G. brasiliensis en el modelo de carcinogénesis inducido por el benzopireno. Material y métodos: El extracto crudo se obtuvo por percolación utilizando 20 g de hojas de G. brasiliensis secas y trituradas y 100 ml de etanol al 70%, durante 24h. Las ratas Wistar fueran divididas en 3 grupos, uno de control sin inducción ni tratamiento, otro inducido por benzopireno (100 mg/kg, diluido en DMSO y administrado por vía intraperitoneal, una sola aplicación) y un grupo tratado por gavage (1ml) con extracto de bacupari 4% (3x/semana, durante 7 semanas, desde la 15ª semana de inducción). Los animales de todos los grupos fueron eutanasiados después de 21 semanas para recoger los pulmones que se procesaron para los análisis histopatológicos (HE) e histoquímicos (azul de toluidina y azul de safranina) para la cuantificación de los mastocitos. Resultados: Los resultados de los análisis histopatológicos mostraron desorganización del parénquima pulmonar, aumento del tejido linfoide asociado a los bronquios, gran afluencia de células inflamatorias y regiones de displasia. Mediante la tinción con azul de toluidina, los mastocitos se identificaron como intactos y degranulados (en proceso de activación). En la tinción conjunta de azul Alcian y Safranina, los mastocitos teñidos de azul representan las fases iniciales del proceso de maduración, mientras que los teñidos de rojo son maduros. La cuantificación mostró una mayor cantidad de mastocitos degranulados, azul Alcian y mixtos (teñidos con azul Alcian-Safranin) en los grupos tratados con el extracto. Conclusión: Los datos indican que el entorno del tumor en los animales tratados muestra una mayor modulación de los mastocitos, con más células jóvenes y activadas. Se llevarán a cabo más análisis para verificar si la activación de los mastocitos promovida por el tratamiento con el extracto se produce para contener o promover el proceso tumoral.(AU)

Naringenin ameliorates inflammation and cell proliferation in benzo(a)pyrene induced pulmonary carcinogenesis by modulating CYP1A1, NFκB and PCNA expression.

Lung cancer is the major cause of cancer-related mortality and is a growing economic burden worldwide. Chemoprevention has emerged as a very effective preventive measure against carcinogenesis and several bioactive compounds in diet have shown their cancer curative potential on lung cancer. Naringenin (NRG), a predominant flavanone found in citrus fruits has been reported to possess anti-oxidative, anti-inflammatory and anti-proliferative activity in a wide variety of cancer. The aim of the present study is to divulge the chemopreventive nature of NRG against benzo(a)pyrene (B[a]P) induced lung carcinogenesis in Swiss albino mice. Administration of B[a]P (50mg/kg, p.o.) to mice resulted in increased lipid peroxidation (LPO), proinflammatory cytokines (TNF-α, IL-6 and IL-1ß) with subsequent decrease in activities of tissue enzymic antioxidants (SOD, CAT, GPx, GR, GST) and non-enzymic antioxidants (GSH and Vit-C). Treatment with NRG (50mg/kg body weight) significantly counteracted all these alterations thereby showing potent anti-cancer effect in lung cancer. Moreover, assessment of protein expression by immunoblotting and mRNA expression by RT-PCR revealed that NRG treatment effectively negates B[a]P-induced upregulated expression of CYP1A1, PCNA and NF-κB. Further, the antiproliferative effect of NRG was confirmed by histopathological analysis and PCNA immunostaining in B[a]P induced mice which showed increased PCNA expression that was restored upon NRG administration. Overall, these findings substantiate the chemopreventive potential of NRG against chemically induced lung cancer in mice.

Human in Vivo Pharmacokinetics of [(14)C]Dibenzo[def,p]chrysene by Accelerator Mass Spectrometry Following Oral Microdosing.

Dibenzo(def,p)chrysene (DBC), (also known as dibenzo[a,l]pyrene), is a high molecular weight polycyclic aromatic hydrocarbon (PAH) found in the environment, including food, produced by the incomplete combustion of hydrocarbons. DBC, classified by IARC as a 2A probable human carcinogen, has a relative potency factor (RPF) in animal cancer models 30-fold higher than benzo[a]pyrene. No data are available describing the disposition of high molecular weight (>4 rings) PAHs in humans to compare to animal studies. Pharmacokinetics of DBC was determined in 3 female and 6 male human volunteers following oral microdosing (29 ng, 5 nCi) of [(14)C]-DBC. This study was made possible with highly sensitive accelerator mass spectrometry (AMS), capable of detecting [(14)C]-DBC equivalents in plasma and urine following a dose considered of de minimus risk to human health. Plasma and urine were collected over 72 h. The plasma Cmax was 68.8 ± 44.3 fg·mL(-1) with a Tmax of 2.25 ± 1.04 h. Elimination occurred in two distinct phases: a rapid (α)-phase, with a T1/2 of 5.8 ± 3.4 h and an apparent elimination rate constant (Kel) of 0.17 ± 0.12 fg·h(-1), followed by a slower (ß)-phase, with a T1/2 of 41.3 ± 29.8 h and an apparent Kel of 0.03 ± 0.02 fg·h(-1). In spite of the high degree of hydrophobicity (log Kow of 7.4), DBC was eliminated rapidly in humans, as are most PAHs in animals, compared to other hydrophobic persistent organic pollutants such as, DDT, PCBs and TCDD. Preliminary examination utilizing a new UHPLC-AMS interface, suggests the presence of polar metabolites in plasma as early as 45 min following dosing. This is the first in vivo data set describing pharmacokinetics in humans of a high molecular weight PAH and should be a valuable addition to risk assessment paradigms.

Nucleotide excision repair gene polymorphisms, meat intake and colon cancer risk.

PURPOSE: Much of the DNA damage from colon cancer-related carcinogens, including heterocyclic amines (HCA) and polycyclic aromatic hydrocarbons (PAH) from red meat cooked at high temperature, are repaired by the nucleotide excision repair (NER) pathway. Thus, we examined whether NER non-synonymous single nucleotide polymorphisms (nsSNPs) modified the association between red meat intake and colon cancer risk. METHODS: The study consists of 244 African-American and 311 white colon cancer cases and population-based controls (331 African Americans and 544 whites) recruited from 33 counties in North Carolina from 1996 to 2000. Information collected by food frequency questionnaire on meat intake and preparation methods were used to estimate HCA and benzo(a)pyrene (BaP, a PAH) intake. We tested 7 nsSNPs in 5 NER genes: XPC A499V and K939Q, XPD D312N and K751Q, XPF R415Q, XPG D1104H, and RAD23B A249V. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were calculated using unconditional logistic regression. RESULTS: Among African Americans, we observed a statistically significant positive association between colon cancer risk and XPC 499 AV+VV genotype (OR=1.7, 95% CI: 1.1, 2.7, AA as referent), and an inverse association with XPC 939 QQ (OR=0.3, 95%CI: 0.2, 0.8, KK as referent). These associations were not observed among whites. For both races combined, there was interaction between the XPC 939 genotype, well-done red meat intake and colon cancer risk (OR=1.5, 95% CI=1.0, 2.2 for high well-done red meat and KK genotype as compared to low well-done red meat and KK genotype, pinteraction=0.05). CONCLUSIONS: Our data suggest that NER nsSNPs are associated with colon cancer risk and may modify the association between well-done red meat intake and colon cancer risk.

Early changes in proteome levels upon acute deltamethrin exposure in mammalian skin system associated with its neoplastic transformation potential.

Deltamethrin, a pyrethroid insecticide, used extensively for pest control has been reported to cause adverse health effects including carcinogenic/toxic effects in animals but the underlying mechanism remains elusive. In the present study, we investigated the effect of deltamethrin after short exposure on early protein expression changes involved in neoplastic transformation in mouse skin, validated the results in human keratinocyte HaCaT cells and thereby explore the possible underlying mechanism. Deltamethrin (4 mg/kg b.wt) and benzo[a]pyrene (B[a]P, 0.05 mg/kg b.wt) were topically applied on Swiss albino mice, respectively. The comparative protein expression profiles with vehicle control were generated by 2-dimensional gel electrophoresis (2-DE) and mass spectrometry. 2-DE maps of deltamethrin and B[a]P treated mouse skin showed 20 and 24 significant (2 fold change, p < 0.05) differentially expressed protein spots, against vehicle controls. However, comparison between them showed relatively similar expression level of 20 spots. Among them, 5 proteins (carbonic anhydrase III, peroxiredoxin-2, calcyclin, superoxide dismutase [Cu-Zn], ubiquitin) are of particular significance as these are involved in cancer-related key processes. Deregulation of these was confirmed at protein and mRNA levels by immunoblotting and RT-PCR in mouse skin and HaCaT cells. Therefore, we conclude that these preliminarily identified proteins might be responsible for the neoplastic transformation of mouse skin epidermal cells and HaCaT cells by deltamethrin. This study proposes complementary mechanism where inhibition of proteasome activator protein (PA200) is responsible for accumulation of ubiquitinated-calcyclin, regulates deltamethrin-induced neoplastic changes in mouse skin and HaCaT cells.

Dibenzo[def,p]chrysene (DBC) suppresses antibody formation in spleen cells following oral exposures of mice.

Dibenzo[def,p]chrysene (DBC) is a potent environmental carcinogen in rodents, fish, and human cells examined in culture. There are numerous similarities between the patterns of cytochrome P-450 (P450) activation of DBC and its covalent binding to DNA and proteins with another polycyclic aromatic hydrocarbon (PAH), 7,12-dimethylbenz[a]anthracene (DMBA). Our lab has previously shown that DMBA produces immunosuppression in rodents and human cell systems. Therefore, the purpose of these studies was to examine the immunotoxicity of DBC in a rodent model that was found to be sensitive to the immunosuppressive effects of DMBA. Data showed that DBC had similar potency to DMBA in producing suppression of a T-dependent antibody response (TDAR) and altered spleen cell subsets in a similar manner as DMBA when DMBA was given by gavage for 5 d in corn oil to mice at doses of 1-100 mg/kg total cumulative doses. T-cell-independent antigen (TNP-Ficoll) responses were quantitatively less sensitive to DBC suppression. It was also found that as with DMBA, DBC produced a persistent immunosuppression, which lasted for at least 4 wk following dosing with a novel pill method for self-administration of DBC. In conclusion, DBC appears to possess many of the same characteristics of DMBA in terms of its immunotoxicity.

Transplacental carcinogenesis with dibenzo[def,p]chrysene (DBC): timing of maternal exposures determines target tissue response in offspring.

Dibenzo[def,p]chrysene (DBC) is a transplacental carcinogen in mice (15mg/kg; gestation day (GD) 17). To mimic residual exposure throughout pregnancy, dams received four smaller doses of DBC (3.75mg/kg) on GD 5, 9, 13 and 17. This regimen alleviated the previously established carcinogenic responses in the thymus, lung, and liver. However, there was a marked increase in ovarian tumors (females) and hyperplastic testes (males). [(14)C]-DBC (GD 17) dosing revealed transplacental distribution to fetal tissues at 10-fold lower concentrations than in paired maternal tissue and residual [(14)C] 3weeks post-dose. This study highlights the importance of developmental stage in susceptibility to environmental carcinogens.

Preliminary physiologically based pharmacokinetic models for benzo[a]pyrene and dibenzo[def,p]chrysene in rodents.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants generated as byproducts of natural and anthropogenic combustion processes. Despite significant public health concern, physiologically based pharmacokinetic (PBPK) modeling efforts for PAHs have so far been limited to naphthalene, plus simpler PK models for pyrene, nitropyrene, and benzo[a]pyrene (B[a]P). The dearth of published models is due in part to the high lipophilicity, low volatility, and myriad metabolic pathways for PAHs, all of which present analytical and experimental challenges. Our research efforts have focused upon experimental approaches and initial development of PBPK models for the prototypic PAH, B[a]P, and the more potent, albeit less studied transplacental carcinogen, dibenzo[def,p]chrysene (DBC). For both compounds, model compartments included arterial and venous blood, flow limited lung, liver, richly perfused and poorly perfused tissues, diffusion limited fat, and a two compartment theoretical gut (for oral exposures). Hepatic and pulmonary metabolism was described for both compounds, as were fractional binding in blood and fecal clearance. Partition coefficients for parent PAH along with their diol and tetraol metabolites were estimated using published algorithms and verified experimentally for the hydroxylated metabolites. The preliminary PBPK models were able to describe many, but not all, of the available data sets, comprising multiple routes of exposure (oral, intravenous) and nominal doses spanning several orders of magnitude.

Human cancer-associated mutations in the Aα subunit of protein phosphatase 2A increase lung cancer incidence in Aα knock-in and knockout mice.

Strong evidence has indicated that protein phosphatase 2A (PP2A) is a tumor suppressor, but a mouse model for testing the tumor suppressor activity was missing. The most abundant forms of trimeric PP2A holoenzyme consist of the scaffolding Aα subunit, one of several regulatory B subunits, and the catalytic Cα subunit. Aα mutations were discovered in a variety of human carcinomas. All carcinoma-associated mutant Aα subunits are defective in binding the B or B and C subunits. Here we describe two knock-in mice expressing cancer-associated Aα point mutants defective in binding B' subunits, one knockout mouse expressing truncated Aα defective in B and C subunit binding, and a floxed mouse for generating conditional Aα knockouts. We found that the cancer-associated Aα mutations increased the incidence of cancer by 50 to 60% in lungs of FVB mice treated with benzopyrene, demonstrating that PP2A acts as a tumor suppressor. We show that the effect of Aα mutation on cancer incidence is dependent on the tumor suppressor p53. The finding that the Aα mutation E64D, which was detected in a human lung carcinoma, increases the lung cancer incidence in mice suggests that this mutation also played a role in the development of the carcinoma in which it was discovered.

Reduced cytochrome P4501A activity and recovery from oxidative stress during subchronic benzo[a]pyrene and benzo[e]pyrene treatment of rainbow trout.

This study assessed the role of aryl hydrocarbon receptor (AHR) affinity, and cytochrome P4501A (CYP1A) protein and activity in polyaromatic hydrocarbon (PAH)-induced oxidative stress. In the 1-100nM concentration range benzo[a]pyrene (BaP) but not benzo[e]pyrene (BeP) competitively displaced 2nM [(3)H]2, 3, 7, 8-tetrachloro-dibenzo-p-dioxin from rainbow trout AHR2α. Based on appearance of fluorescent aromatic compounds in bile over 3, 7, 14, 28 or 50days of feeding 3µg of BaP or BeP/g fish/day, rainbow trout liver readily excreted these polyaromatic hydrocarbons (PAHs) and their metabolites at near steady state rates. CYP1A proteins catalyzed more than 98% of ethoxyresorufin-O-deethylase (EROD) activity in rainbow trout hepatic microsomes. EROD activity of hepatic microsomes initially increased and then decreased to control activities after 50days of feeding both PAHs. Immunohistochemistry of liver confirmed CYP1A protein increased in fish fed both PAHs after 3days and remained elevated for up to 28days. Neither BaP nor BeP increased hepatic DNA adduct concentrations at any time up to 50days of feeding these PAHs. Comet assays of blood cells demonstrated marked DNA damage after 14days of feeding both PAHs that was not significant after 50days. There was a strong positive correlation between hepatic EROD activity and DNA damage in blood cells over time for both PAHs. Neither CYP1A protein nor 3-nitrotyrosine (a biomarker for oxidative stress) immunostaining in trunk kidney were significantly altered by BaP or BeP after 3, 7, 14, or 28days. There was no clear association between AHR2α affinity and BaP and BeP-induced oxidative stress.

Early genotoxic effects in gill cells and haemocytes of Dreissena polymorpha exposed to cadmium, B[a]P and a combination of B[a]P and Cd.

The aim of this study was to assess the genotoxic potential of environmentally relevant concentrations of Cd on the zebra mussel, an important freshwater sentinel organism, and to determine the stability of DNA damage in gill cells and haemocytes. The oxidative DNA damage and the co-genotoxicity of Cd in combination with B[a]P were investigated. We measured DNA damage in haemocytes and gill cells of zebra mussels exposed for 11 days to a constant concentration of Cd (10µg/L), B[a]P (10µg/L) or the two combined chemicals (10µg/L+1µg/L). Enzymatic dissociation of gills with dispase gave the lower percentage DNA in tail, compared with collagenase/dispase or collagenase. Bioaccumulation of cadmium in the soft tissues of mussels exposed to CdCl(2) or CdCl(2)+B[a]P increased in a time-dependent manner indicating that both exposures were effective. Cd (10µg/L) is genotoxic only during the first 3 days of exposure in gill cells, while in haemocytes the genotoxicity of Cd was observed later. B[a]P (10µg/L) induced an early increase of DNA damage in gill cells (after 10h and 1 day), while in both gill cells and haemocytes, B[a]P caused a marked increase of DNA damage after 3 days of exposure. The Cd+B[a]P mixture decreased the DNA-damaging effect of Cd and B[a]P in both cell types. Cd induced an increase of DNA damage in Fpg-treated slides, indicating that Cd contributed to oxidative DNA damage. Cadmium induced a cytogenetic effect in gill cells, assessed by the number of micronuclei, throughout the duration of the exposure, while B[a]P did not induce any cytogenetic effect. B[a]P, Cd and Cd+B[a]P induced a transient increase in the number of bi-nucleated cells. Our data clearly show that gills are more sensitive to Cd and B[a]P, which makes them more suitable for future bio-monitoring studies.

3-Hydroxybenzo(a)pyrene as a biomarker of dermal exposure to benzo(a)pyrene.

The aim of this study was to determine the percutaneous absorption flux of BaP (20 microg/cm(2) in ethanol) and the usefulness of urinary 3-OHBaP as a bio-indicator of dermal exposure to BaP. The percutaneous absorbed dose and absorption flux were estimated by comparison with intravenous administration of BaP (0.01 and 0.05 mg/kg in Cremophor) as reference way. A percutaneous absorption flux of 0.37 microg/cm(2)/h was determined by killing groups of rats, following exposure time of 4.5 and 24 h. [(14)C] skin content was 3.1 microg/cm(2), after 24 h exposure to BaP. Total urinary 3-OHBaP accounted for 0.4% of the real absorbed dose, which was fourfold higher than the percentage of an intravenous dose excreted as 3-OHBaP. This finding reveals that percutaneous absorption of BaP, based on the ratio of urinary excretion of 3-OHBaP following percutaneous exposure compared to percutaneous absorption following intravenous administration of BaP, is overestimated in the rat. In vitro, BaP was intensively metabolised by rat skin. Unchanged BaP and 3-OHBaP in receptor fluid accounted for 50 and 30% of the total radioactivity. This percutaneous first past effect of BaP in rats could, in part, explain the higher urinary excretion ratio of 3-OHBaP compared to the value based on intravenous administration of BaP. Conversely, BaP was largely lower metabolised as 3-OHBaP during percutaneous absorption by humans, so BaP absorption flux should be overestimated to a lesser extent in humans than in rats.

Mutations induced by benzo[a]pyrene and dibenzo[a,l]pyrene in lacI transgenic B6C3F1 mouse lung result from stable DNA adducts.

Dibenzo[a,l]pyrene (DB[a,l]P) and benzo[a]pyrene (B[a]P) are carcinogenic polycyclic aromatic hydrocarbons (PAHs) that are each capable of forming a variety of covalent adducts with DNA. Some of the DNA adducts formed by these PAHs have been demonstrated to spontaneously depurinate, producing apurinic (AP) sites. The significance of the formation of AP sites as a key event in the production of mutations and tumours by PAHs has been a subject of ongoing investigations. Because cells have efficient and accurate mechanisms for repairing background levels of AP sites, the contribution of PAH-induced AP site mutagenesis is expected to be maximal in conditions where those induced AP sites are produced in significant excess of the endogenous AP sites. In this study, we investigated the effect of two dosing regimens on the mutagenicity of DB[a,l]P and B[a]P in vivo using the Big Blue(R) transgenic mouse system. We compared administration of a single highly tumorigenic dose of each PAH with a fractionated delivery of the same total dose administered over 5 days, with the expectation that PAH-induced AP sites would be produced at a greater margin above background levels in animals receiving the high single dose than in the animals receiving the fractionated doses. Treatment with DB[a,l]P yielded a 2.5-fold (single dose) to 3-fold (fractionated dose) increase in mutant frequencies relative to controls. Both single-dose and fractionated dose treatment regimens with B[a]P produced about a 15-fold increase in mutant frequencies compared to controls. The mutations induced by B[a]P and DB[a,l]P correlated with the stable covalent DNA adducts produced by each. These mutation results are consistent with the previously identified stable covalent DNA adducts being the promutagenic lesions produced by these two PAHs and do not support a major role for depurinating adducts, contributing to PAH-induced mutagenesis in mouse lung in vivo.

Benzo[a]pyrene-3,6-dione inhibited VEGF expression through inducing HIF-1alpha degradation.

Vascular endothelial growth factor (VEGF) is a potent angiogenesis inducer for tumor growth and angiogenesis. Benzo[a]pyrene (BaP) belongs to polycyclic aromatic hydrocarbons (PAHs) and is known to cause carcinogenesis. But the effects of BaP and its metabolites on VEGF and HIF-1 expression remain to be elucidated. In this study, we found benzo[a]pyrene-3,6-dione (BPQ), but not BaP and benzo[a]pyrene-7,8-diol-9,10-epoxide (BPDE) inhibited VEGF expression in a dose-dependent manner. BPQ inhibited VEGF transcriptional activation through hypoxia-inducible factor 1 (HIF-1) binding site. BPQ specifically decreased HIF-1alpha, but not HIF-1beta subunit expression in A549 cells. We found that BPQ did not inhibit HIF-1alpha mRNA level, but inhibited its protein expression in a proteasome-dependent manner. To further clarify the mechanism of BPQ in regulating HIF-1alpha stability, we found that BPQ inhibited HIF-1alpha protein expression by the increase of the proteasome-dependent degradation, and by the disruption of HIF-1alpha and Hsp90 association.

Antiviral activity of liposomal preparations of antibiotic geliomycin.

A liposomal preparation with maximally possible content of incorporated geliomycin was obtained. Its cytotoxicity was studied in a culture of human embryonal diploid fibroblasts. Antiviral activity was studied on a model of cytomegaloviral infection in vitro by the capacity to plaque formation. Liposomal geliomycin was 10-fold less toxic for human cells than the solution of the antibiotic in DMSO and exhibited antiviral activity towards cytomegaloviral infection at a concentration of 0.042 microg/ml.

Dibenzo[A,L]pyrene-induced genotoxic and carcinogenic responses are dramatically suppressed in aryl hydrocarbon receptor-deficient mice.

Dibenzo[a,l]pyrene (DB[a,l]P), a notorious air pollutant, is the most powerful carcinogenic polycyclic aromatic hydrocarbon (PAH) ever tested. Although the carcinogenicity of PAH may be primarily mediated by the aryl hydrocarbon receptor (AhR), the in vivo role of AhR in skin carcinogenesis remains to be defined. In this context, we investigated the genotoxic and carcinogenic responses of the AhR-deficient mouse skin to DB[a,l]P. A single painting resulted in a striking epidermal hyperplasia in AhR+/+ mice but not in AhR-/- mice. Bromodeoxyuridine-labeling index and accumulation of p53 protein in epidermal cells of AhR+/+ mice were 8- and 33-fold higher than those of AhR-/- mice, respectively. 32P-Postlabeling assay for DB[a,l]P-DNA adducts displayed a 2-fold increase in the AhR+/+ mouse skin. After DB[a,l]P exposure, AhR-/- mice arranged a nearly 60% reduction in the induction of epidermal cytochrome P450 (CYP)1A1, but CYP1B1 was constitutively expressed in both genotypes of mice, irrespective of DB[a,l]P treatment. As compared with AhR+/+ mice, AhR-/- mice had both significantly lower incidence (100% vs. 33%) and multiplicity (2.7 vs. 0.46) of skin tumors by the complete carcinogenesis study. These observations indicate that a reduced tumor yield in AhR-/- mice may be secondary to reduction of inducible CYP1A1 activation and subsequent DNA adduction. It is evident from our continuous work that although AhR is likely to play a central role in epidermal proliferation and possibly neoplastic transformation, the relative importance of AhR for carcinogenesis may be different among PAH examined.

Effect of single neonatal or repeated benzpyrene exposure on the serotonin content of immune cells in young male rats.

In earlier experiments single benzpyrene treatment of newborn rats caused strong alterations in the endorphin content of adult rats' immune cells. In the present experiments young (4-6 weeks old) male rats were studied for demonstrating the effect of the single neonatal or repeated (neonatally and at weanling) benzpyrene exposure on the serotonin content of immune cells (blood lymphocytes, monocytes, granulocytes; peritoneal fluid lymphocytes, mast cells, monocytes and granulocytes, thymic lymphocytes). Flow cytometric analysis showed that 50 microg benzpyrene treatment of five-week-old animals was ineffective after 5 days and this was the situation four weeks after single neonatal (20 microg) benzpyrene exposure. However, the repeated treatment of neonatally benzpyrene exposed 4 weeks old animals after 5 days resulted in elevated blood and thymic lymphocyte serotonin amount and in one index (peritoneal monocyte-granulocyte group) reduced serotonin content. This means that neonatal benzpyrene treatment does not influence directly the serotonin content (production or transport) of immune cells (unlike to the endorphin content) however, sensitizes them to a following benzpyrene exposure. The results widen the list of harmful effects (influencing steroid receptor binding, sexual behavior and immune cells' endorphin content) of perinatal benzpyrene exposure.

Effect of single neonatal treatment with the soy bean phytosteroid, genistein on the sexual behavior of adult rats.

Hormonal imprinting develops during the perinatal critical period, when the target hormone meets the yet unmatured receptor. As a consequence of imprinting the receptor accomplishes its maturation reaching the binding capacity characteristic to adults. In this period in the presence of foreign molecules similar to the target hormone faulty imprinting may occur with life-long consequences. Soy bean contains phytosteroids which can mimic estrogen effects. In the present experiments single genistein (20 microg) or combined genistein + benzpyrene (20 microg) treatments were done neonatally and the sexual behavior of male and female adult animals was studied. Genistein significantly increased the lordosis quotient of females, which was compensated by neonatal benzpyrene treatment. Genistein also enhanced the sexual activity of males, and this was significantly not reduced by parallel benzpyrene treatment. The results show that neonatal genistein exposure can imprint sexual activity for life and the presence of a second imprinter can modify genistein's behavioral effect.

Effect of a single treatment (imprinting) with genistein or combined treatment with genistein+benzpyrene on the binding capacity of glucocorticoid and estrogen receptors of adult rats.

Hormonal imprinting takes place perinatally at the first encounter between the hormone and its target receptor. This is needed for the normal finishment of the maturation of the receptor-signal transduction system. In excess of foreign molecules, which can also bind to the receptor, faulty imprinting develops with life-long consequences. Genistein, a soybean phytosteroid (isoflavone), has estrogen-like effects and can be bound by steroid receptors. In the present experiments, single neonatal treatment (imprinting) with 20 microg of genistein, or combined treatment with 20 microg of genistein+20 microg of benzpyrene was done and liver and thymus glucocorticoid receptors of adult male and female rats and uterine estrogen receptors were studied. There was no difference in the binding capacity of uterine estrogen receptors. Genistein treatment alone caused a significant reduction of liver glucocorticoid receptor density in males; however, there were no other significant alterations. After combined genistein+benzpyrene treatment, more.than half of the thymus and liver glucocorticoid receptor values significantly changed. The results call attention to the imprinting-modifying effect of a second (environmental) imprinter.