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PubMed1992

A possible modulatory influence of melatonin on representative phase I and II drug metabolizing enzymes in 9,10-dimethyl-1,2-benzanthracene induced rat mammary tumorigenesis.

The oncosuppressive effect of melatonin on 9,10-dimethyl-1,2-benzanthracene (DMBA) induced rat mammary tumorigenesis led us to assess its possible modulatory influence on representative hepatic and mammary drug metabolizing enzymes in DMBA treated female Holtzman rats, reared in short and long photoperiods. Melatonin treated rats in either photoperiod showed a significant induction in hepatic and mammary levels of glutathione (GSH) and cytosolic activities of glutathione S-transferase (GST) when compared with the corresponding controls, along with a significant drop in hepatic microsomal contents of cytochromes b5 and P450. This induction of GSH and GST, and depletion of cytochromes b5 and P450 by melatonin may possibly be related to its anticarcinogenic potential in this tumor model.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1980

Adnexal participation in formation of cutaneous tumors following topical application of 9,10-dimethyl-benzanthracene.

The response of the hair follicle apparatus to topical 9, 10-dimethyl-benzanthracene applications was studied in several strains of mice and rats. Early follicular destruction in mice was associated with subsequent formation of large number of epithelial tumors. Preserved follicular structures in rats proliferated with the formation of low incidence of adenomas and trichoepitheliomas. Hair nevi, hairfollicle nevi and trichofolliculomas, unrelated to treatment, were observed in several animal strains.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1995

Induction of carcinomas and sarcomas by 9,10-dimethyl-1,2-benzanthracene administration into the hamster maxillary sinus.

To determine whether the local administration of 9,10-dimethyl-1,2-benzanthracene (DMBA) into the hamster maxillary sinus induced carcinoma at the injected site, hamsters were injected with 30 microliters of 0.5% solution of DMBA in dimethyl sulfoxide (DMSO) through the infraorbital foramen into the maxillary sinus once weekly for 10 weeks (Group 2). Another group of hamsters (Group 1) received similar injections of 30 microliters of DMSO only. In a third group of animals (Group 3), a roll of oxycellulose was inserted into the maxillary sinus and 40 microliters of a 2% solution of DMBA in DMSO was injected once. Sinonasal carcinomas were demonstrated in 73% (8/11) of the hamsters in Group 2 and sarcomas were shown in 73% (8/11) of the hamsters in Group 3, as well as some carcinomas. No tumors were seen in the Group 1 hamsters. Histologic examination revealed squamous cell carcinomas arising from the surface epithelium and submucous glands of the nasal cavity and maxillary sinus. These findings indicate that the intrasinal administration of a 0.5% solution of DMBA in DMSO is a reliable method for inducing maxillary sinus cancer.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1975

Inhibition by 2,4-dinitrophenol of 9,10-dimethyl-1,2-benzanthracene carcinogenesis in the hamster cheek pouch.

After topical treatment of cheek pouches of 10 hamsters with 9,10-dimethyl-1,2-benzanthracene and 2,4-dinitrophenol for 10 weeks no carcinomas developed in any of the animals. After treatment of 10 animals with the carcinogen only, there were 49 carcinomas in the 8 survivors. Inhibition of chemical carcinogenesis by dinitrophenol was tentatively attributed to suppression of ATP synthesis and to activation of ATPase by dinitrophenol.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1987

Influence of chronic melatonin on 9,10-dimethyl-1,2-benzanthracene-induced mammary tumors in female Holtzman rats exposed to continuous light.

Daily treatment of 'functionally' and surgically pinealectomized female Holtzman rats reared in continuous light (light:dark schedule, 24L:OD) with oral melatonin (100 micrograms/day/rat) initiated 30 days prior to and 90 days following 9,10-dimethyl-1,2-benzanthracene (DMBA) administration on day 55 of age, resulted in a highly significant suppression of mammary tumor incidence and prolongation of latency period of tumor appearance (p less than 0.001). An identical treatment schedule of melatonin to intact rats given DMBA, housed in short photoperiods (10L:14D), also resulted in a significant suppression of tumor incidence (p less than 0.05), though the latency period of tumor appearance was not prolonged. These results demonstrate for the first time that replacement or additive manipulations of melatonin from puberty to adulthood plays a critical role in the suppression of DMBA-induced mammary tumors.

9,10-Dimethyl-1,2-benzanthracene↗
PubMedDate not supplied

Ultrastructural study of melanocytic lesions in albino guinea pigs induced with 7,12-dimethyl-benzanthracene.

We studied the fine structure of benign, premalignant and malignant melanocytic lesions induced in Dunkin-Hartley guinea pigs by means of topical application of 7,12-dimethyl-benzanthracene (DMBA). The most noteworthy characteristics of the atypical melanocytes (melanocytic dysplasia and melanomas) were the variable morphology and structure, and, in particular, the aberrant character of the melanosomes. The melanocytes presented irregularity of nuclear outlines with frequent lobulation. The heterochromatin was usually found in thick clumps reinforcing the nuclear membrane, and the nucleoli were usually multiple. The melanosomes were ellipsoidal and spherical with a pattern that was lamellar, concentric, incomplete, and even microgranular and microvesicular. The melanization was usually in thick, irregular clumps. Melanosome complexes were always present.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1983

Potentiation of Friend viral leukemogenesis by 9,10-dimethyl-1,2-benzanthracene in two strains of mice.

The polycyclic aromatic hydrocarbon, 9,10-dimethyl-1,2-benzanthracene (DMBA) produced malignancy involving the spleen in SJL/J and B10SJF1 mice when injected ip at 500 micrograms per mouse either alone or in combination with threshold doses of Friend leukemia virus (FLV). The mice that received both chemical and virus died significantly sooner than mice that received either chemical or virus alone, and a synergism between DMBA and FLV was demonstrated in both the virus-resistant B10SJF1 hybrids and virus-sensitive SJL/J mice.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1989

Sequential analysis of experimental oral carcinogenesis in hamster cheek pouch using 9,10-dimethyl-1-2-benzanthracene.

The utility of hamster cheek pouch model for studies on oral carcinogenesis has been explored using 9,10-dimethyl-1-2-benzanthracene as a carcinogen. Based on the morphological, histopathological and electron microscopic observations the hamster cheek pouch carcinogenesis can be separated into different stages starting from the normal to the fully grown carcinomas. This system is reliable, precise, consistent and can be used for the evaluation of different agents for initiating or promoting effects and as well as for the studies on mechanism of oral carcinogenesis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMedDate not supplied

[Anatomo-pathologic and ultrastructural study in a case of melanoma in the golden Syrian hamster chemically induced by 9,10 dimethyl-1,2-benzanthracene (DMBA) and transplantable].

Pigmented melanomas were induced in the Syrian golden hamster by oral administration of 9, 10-dimethyl 1,2-benzanthracene. The primary tumors were grafted into new animals to obtain a series of transplantable tumors. The grafted tumors show the malignant characters which are not present in the primary tumors. These were studied clinically, histologically and ultrastructurally. We believe that this transformation occured perhaps as a consequence of the selection of cells which have a more prominent tendency toward malignancy. This selection could be explained by a greater resistance of lesser pigmented melanocytes or by their weak immunologic capacity. The malignant potential of these cells could eventually be correlated with the presence of viral particles which act as cocarcinogens.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1994

Variations in nucleolar organizer regions during 9-10 dimethyl1-2 benzanthracene induced tongue carcinogenesis in rats.

The quantitative and qualitative changes of transcriptionally active nucleolar organizer regions (NORs) identified by silver staining (AgNORs) were observed in rat tongue lesions induced by 9-10 dimethyl 1-2 benzanthracene (DMBA). Epithelial hyperplasia, mild, moderate dysplasia and severe dysplasia (with or without invasive squamous cell carcinoma) were induced 4,6,8 & 10 weeks respectively after implantation of 5 mg DMBA in the submucosa of rat's tongues. A general trend towards an increase in the mean AgNOR counts with longer time and resultant histopathological findings was observed, where the lowest value (2.44 +/- 1.00) was found in specimens showing epithelial hyperplasia (4 weeks after DMBA implantation) and the highest value in those showing severe dysplasia with invasive squamous cell carcinoma (10 weeks after DMBA implantation). Clumping and irregularity of AgNOR dots were demonstrated in DMBA treated specimens and were found to increase with higher degrees of epithelia dysplasia. The dispersal of the AgNOR dots in the nucleoplasm indicating high cellular activity was characteristically evident in specimens showing severe dysplasia with invasive squamous cell carcinoma. Our results suggest that although AgNORs can be useful as a qualitative marker of cellular activity at the early stages of DMBA tongue carcinogenesis, counting the AgNOR dots cannot be relied upon in discriminating the different degrees of induced cellular changes.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1988

Phenobarbital, dexamethasone and benzanthracene induce several cytochrome P450 mRNAs in rat hepatoma cells.

Hepatoma cells derived from the Reuber H35 rat hepatoma express cytochrome P450 enzymes of two major families: polycyclic aromatic hydrocarbon-inducible forms are found in both differentiated and dedifferentiated cells while phenobarbital (PB)-inducible forms are found only in differentiated cells. We report here that (i) benzanthracene and PB induce P450 c mRNA in differentiated and dedifferentiated cells and (ii) dexamethasone and PB induce P450 b/e and/or P450 PB1 mRNAs in differentiated cells but not in dedifferentiated cells.

Animals↗
PubMed1995

The genotoxicity of benzanthracenes: a quantitative structure-activity study.

Molecular orbital (MO) evaluations of a series of 14 methyl-substituted benz[alpha]anthracenes, calculated by the complete neglect of differential overlap (CNDO/2) method, are reported. By quantitative structure-activity relationship (QSAR) analysis, the carcinogenic and mutagenic potencies of these compounds have been shown to be correlated with their electronic structures, namely, with the magnitude of the energy of the lowest unoccupied molecular orbital (LUMO). The log mutagenicity potencies for the series of 14 benz[alpha]anthracenes are negatively dependent on E(LUMO), with a correlation coefficient of 0.82, which is increased to 0.90 by inclusion in the QSAR of a second variable, namely Q3H, the electronic density in the highest occupied molecular orbital, E(HOMO), of carbon-3. E(LUMO) is also negatively correlated with mouse carcinogenicity of the benzanthracenes, with a correlation coefficient of 0.88 for tumour incidence, and of 0.83 for log carcinogenicity index. The carcinogenicity and mutagenicity of the individual members of this series of polycyclic aromatic hydrocarbons are discussed in terms of the relationships between molecular structure, electron density, metabolic activation and covalent binding of reactive intermediates.

Animals↗
PubMed1990

Induction of cytochrome P(1)450 RNA and benzo[a]pyrene metabolism in primary human hepatocyte cultures with benzanthracene.

Exposure of cells to microsomal enzyme inducers can modify the potency of many carcinogens. We have examined the steady-state level of RNA from the P(1)450 gene and the metabolism of benzo[a]pyrene (BP) in primary cultures of human hepatocytes exposed for up to 4 days to 12.5 microM benzanthracene (BA), and in uninduced control cultures. While the steady-state levels of RNA from the P(1)450 gene were nondetectable in uninduced (DMSO only) human hepatocytes, 12.5 microM BA-induced AHH activity, BP metabolism, and/or P(1)450-specific RNA in hepatocytes from seven human cases were investigated. RNA levels specific for the P(1)450 gene appeared maximal at 24 hr following exposure to BA, whereas, the protein, as determined by AHH enzyme activity from BA-induced hepatocytes, continued to increase up to the last time point examined, 72 hr. BA induction for 96 hr increased metabolism of BP (initial concentration of BP, 10 microM) over a time course of 3, 6, 12, and 24 hr of incubation with BP compared with that of controls. The major metabolites of BP produced by human hepatocytes in culture were the unidentified polar BP metabolite(s), possibly polyhydroxylated. BA induction caused approximately a twofold increase in these metabolites. BA-induced cultures showed an increase in glutathione conjugation compared to that in controls. The percentage of glucuronide and sulfate conjugates remains similar in all cultures. Total binding of tritium label BP to DNA was 1.3-fold to fivefold greater in induced cultures, and related more to total metabolism than to production of a specific metabolite. Exposure of human hepatocytes in vitro to BA leads to a large increase in the steady-state level of the RNA specific for the P(1)450 gene and an increase metabolism of BP.

Adolescent↗
PubMed1983

Effects of methylcholanthrene and benzanthracene on blastogenesis and aryl hydrocarbon hydroxylase induction in splenic lymphocytes from three inbred strains of mice.

The effects of polycyclic aromatic hydrocarbons (PAH) such as benzanthracene (BA) and methylcholanthrene (MCA) on 3H-thymidine incorporation and aryl hydrocarbon hydroxylase (AHH) induction were assayed in mitogen-activated and non-activated splenic lymphocyte cultures derived from three strains of mice (C57BL, C3H and DBA/2). Results of three separate experiments on blastogenesis and the substrate induction of AHH were statistically significant. In mitogen-activated and non-activated lymphocytes from C57BL and C3H mice (AHH responsive strains) the percentage of blastogenesis induced by BA or MCA was higher than in lymphocytes from the non-responsive strain (DBA/2). On the basis of the PAH concentrations used MCA and BA were similar as inducers of blastogenesis and of AHH activity. AHH induction was measurable only in mitogen-activated lymphocytes and showed a non-linear relation to blastogenesis. In responsive strains, 10 microM oF BA or 1.5 microM of MCA induced AHH 2-5 fold, while in non-responsive mice induced AHH was very close to the basal level. This difference between the level of induction of lymphoblast formation and AHH in responsive and non-responsive strains of mice may be related to different subpopulations of lymphocytes in spleen or other lymphatic organs.

Animals↗
PubMed1977

In vitro induction of aryl hydrocarbon hydroxylase in human pulmonary alveolar macrophages by benzanthracene.

Aryl hydrocarbon hydroxylase (AHH) was induced in human pulmonary alveolar macrophages (PAMs) cultured in the presence of benzanthracene. Time and dose--response curves were established for in vitro induction of this enzyme system in PAMs. In addition, a positive correlation was noted between the level of AHH activity in freshly lavaged PAMs and the in vitro inducibility of the enyzme in these cells from either nonsmokers or cigarette smokers. Measurements of the inducibility of AHH in cultured human PAMs provide an experimental system suitable for studying the mechanisms responsible for the initiation of pulmonary carcinogenesis.

Adult↗
PubMed1979

Aryl hydrocarbon hydroxylase induction in mitogen-stimulated lymphocytes by benzanthracene or cigarette tars adsorbed to asbestos fibers.

Human mitogen-stimulated lymphocytes, cultured in the presence of amosite asbestos (AS), demonstrated a slight increase in aryl hydrocarbon hydroxylase (AHH) activity compared with non-induced (control) cultures (P = 0.005). A much greater increase in enzyme activity occurred following addition of the inducers benzanthracene (BA) or cigarette tars (CT) to cell cultures (P less than 0.001 in both instances). Significant enzyme induction also occurred when AS fibers were first preincubated with CT or BA, washed with acetone, then added to lymphocyte cultures (P less than 0.003 in all instances). This increase in AHH activity was not as great, however, as the induction observed when BA or CT was added to cell cultures. No further increase in enzyme activity was noted when AS and CT or AS and BA were simultaneously added to culture lymphocytes (P greater than 0.070 in all instances). The results demonstrate that polycyclic aromatic hydrocarbons (PAH), such as BA and other components of CT, are adsorbed and transported by amosite AS particles. These AS-PAH complexes are capable of inducing AHH in cultured human lymphocytes.

Adsorption↗
PubMed1997

Infrared spectroscopy of matrix-isolated polycyclic aromatic hydrocarbon cations. 4. The tetracyclic PAH isomers chrysene and 1,2-benzanthracene.

The mid-infrared spectra of the polycyclic aromatic hydrocarbon (PAH) cations of the tetracyclic isomers chrysene (C18H12+) and 1,2-benzanthracene (C18H12+) are presented. As with previous PAH cations studied to date, the CC stretching and CH in-plane bending mode absorptions are about an order of magnitude stronger than the aromatic CH out-of-plane bending absorptions and nearly 2 orders of magnitude more intense than the corresponding bands in the neutral molecule. The CH bands arising from the out-of-plane bends in the cation are slightly weaker than the corresponding bands in the neutral species. The strongest cation bands of these species fall between 1300 and 1330 cm-1, close to the peak of the most intense interstellar emission feature in HII regions and reflection nebulae. A strong PAH cation band at slightly higher frequency than 1300 cm-1 may be associated with an asymmetric CC stretching vibration involving rings adjacent to the kink in the chain of aromatic rings.

Argon↗
PubMed1976

1,2-Benzanthracene in soil.

Samples from three cultivated soils and one from a roadside, all in Ontario, were found to contain less than 1 to 68 ppb of 1,2-Benzanthracene (BA). Two plots subjected to stubble (residue of wheat crop) burning annually for 15 years did not contain significant amounts of BA, although polyaromatic hydrocarbons, including BA, result from pyrolysis of most organic matter.

Benz(a)Anthracenes↗