Formation and persistence of DNA adducts in epidermal and dermal mouse skin exposed to benzo(a)pyrene in vivo.

Tritiated benzo(a)pyrene was applied topically to 35 old male Swiss mice that received 250 nMole (0.63 mCi) per mouse in 150 microliters acetone. At each time point of study, 1, 3 and 7 days, 10 animals were killed, the skin was removed and the susceptible epidermic cells were separated from resistant dermis.

[Specific induction by phorbol ester of the gene transcription and of the activity of ornithine decarboxylase in two control and transformed epithelial cell lines. Modulator effect of anti-inflammatory agents].

The mechanism of ornithine decarboxylase (ODC) induction by phorbol ester (TPA) has been studied in two permanent epithelial cell lines, a control (Ctr) and a Benzo (a) pyrene transformed line (BaP-tr); the degree of ODC gene expression (ODC-mRNA) was evaluated in comparison to the ODC activity. A small dose of TPA (4 x 10(-8) M) highly induced ODC activity in these cells. The induction levels differed however, corresponding respectively to 4:1 (induced: basal ODC) in Ctr cells and to 2:1 in BaP-tr cells.

Inhibition of chemically-induced skin carcinogenesis in mice by peanut oil preparations.

Epidermal hyperplasia and sebaceous gland destruction - good indicators of carcinogenic potential - were studied in short-term mouse skin experiments following application of BaP and TPA dissolved either in a peanut oil mixture or in acetone. Subsequently, the carcinogenicity of BaP and DMBA alone or in association with TPA was dissolved in the same vehicles, and determined in mouse long-term skin tests. In parallel, ODC activity and binding to DNA, RNA and proteins were examined in epidermal cells after exposure to TPA and BaP respectively.

1-Chloromethylpyrene: a reference skin sensitizer and genotoxin.

1-Chloromethylpyrene (1-CMP) has been evaluated as a model mutagen and toxin related to the ultimate electrophiles derived from benzo[a]pyrene and 1-nitropyrene. It was mutagenic to Salmonella (greater than 100 pg/plate) and exceptionally reactive to DNA when assessed by the 32P-postlabelling technique. 1-CMP was inactive in a mouse bone micronucleus assay when administered by gavage, probably due to hydrolysis, whose kinetics have been studied (t1/2 approximately 23 min at 37 degrees C).

Study of various transforming effects of the anabolic agents trenbolone and testosterone on Syrian hamster embryo cells.

Trenbolone, a synthetic androgen together with testosterone, a natural androgen, were studied comparatively for their transforming effects on Syrian hamster embryo (SHE) cells. The data indicated that both androgens exhibited weak positive complete transforming activities without a dose response relationship. Trenbolone is more toxic than testosterone when the concentrations tested are higher than 10 micrograms/ml, but is less able to transform SHE cells.

Dose and frequency effect in mouse skin tumor promotion.

In order to study the influence of both dose and application frequency of tumor-promoting agents on tumor development, we conducted a large-scale mouse skin two-stage carcinogenesis experiment. The back skins of 1110 CD-1 mice were painted once with 50 micrograms benzo(a)pyrene. These mice were divided into 24 groups according to subsequent schedules of 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment.

Epidermal cell proliferation and modulation of the protective potency of dexamethasone against phorbol ester-induced ornithine decarboxylase activity.

Treating mouse skin with dexamethasone (DXME, 1 mumol) after a single TPA (3.25 nmol) application, inhibited both the dermal inflammatory reaction and the induction of epidermal ornithine decarboxylase (ODC) activity. At the hyperplastic stage, DXME was active against inflammation, though inhibited weakly the induction of ODC.

Biological effects of asbestos fibres on rat lung maintained in vitro.

The in vitro systems used to determine whether asbestos acts as an initiator or as a promoter have failed to give definitive answers. We studied the effect of chrysotile and crocidolite in an initiation-promotion model on the Fischer rat embryo lung. Two assay systems were used in succession: organ culture of the lung cultured for 24 days and epithelial cell culture derived from treated or untreated explants cultured for 25 passages.

Effect of long-term ingestion of asbestos fibres in rats.

The effects of ingested asbestos fibres were studied in Wistar Han rats. Chrysotile and a mixture of chrysotile/crocidolite (75%/25%) in palm oil were given for 24 months to 70 males and 70 females per group (daily doses 10, 60 and 360 mg); one control group was fed with normal diet, a second with normal diet plus palm oil. The animals were observed for a further 6 months after the end of the treatment.

Transforming activities of sodium fluoride in cultured Syrian hamster embryo and BALB/3T3 cells.

The transforming activity of sodium fluoride was studied in the SHE and the BALB/3T3 cell culture systems. Initiating and promoting activities were then investigated by means of the orthogonal methodology. Sodium fluoride was found to induce morphological transformation of SHE cells seeded on a feeder layer of X-irradiated cells at high concentrations (75-125 micrograms/ml).

Use of the orthogonal design method to study the synergistic effects of asbestos fibres and 12-O-tetradecanoylphorbol-13-acetate (TPA) in the BALB/3T3 cell transformation system.

An orthogonal design method was used to study the transforming effects of chrysotile and crocidolite asbestos fibres in BALB/3T3 cells. Three experiments, designed by tables L9 (3(4)), L8 (2(7)) and L6 (3(1) x 2(2)) of the orthogonal method respectively, were performed separately. The results indicate exponential reductions in survival of treated cells concomitant with a linear increase in exposure concentrations from 0.

Sister chromatid exchanges and chromosomal aberrations in lymphocytes of nurses handling cytostatic agents.

A cohort study of 29 nurses who constantly handled cytostatic drugs, and 29 controls matched according to sex and age, was carried out between 1983 and 1986. Cytogenetic damage was assessed by sister chromatid exchanges (SCE) and chromosomal aberrations. No significant increase in mean number of SCE was found for nurses (7.

[Epigenetic mechanism of tumor promotion. Interrelationship between inflammation and ornithine decarboxylase activity induced in vitro by the carcinogenic 12-O-tetradecanoyl-phorbol-13-acetate].

Topical application of 2 micrograms 12-O-tetradecanoyl-phorbol-13-acetate (TPA) regularly induced two early events in mouse skin: inflammatory reaction localized in dermal compartment and stimulation of ornithine decarboxylase activity in epidermal cells, in relation to polyamine synthesis and cell division. These reactions were followed, after 48 hrs. by an epidermal hyperplasia.

Sensitivity of the skin of different mouse strains to the promoting effect of 12-0-tetradecanoyl-phorbol-13-acetate.

The sensitivity of the skin of Swiss DBA/2 and C57B1/6 mice was compared in two-stage carcinogenicity experiments. Groups of 30 mice were treated once with 7,12-dimethylbenz(a)anthracene (DMBA) (50 micrograms/mouse) which was applied to the shaved dorsal skin as initiator and, starting one week later, 12-0-tetradecanoyl-phorbol-13-acetate (TPA) was applied thrice-weekly at doses of either 0.04, 0.

Initiating, promoting and carcinogenic activities of three naphthofurans in a mouse skin long-term study.

The initiating, promoting and carcinogenic activities of three naphthofurans, 2-nitro-7-methoxynaphto[2,1-b]furan (A), 2-nitronaphtho[2,1-b]furan (C) and 7-methoxynaphtho[2,1-b]-furan (E), were determined in a long-term assay using CD1 mice, by means of a two-step skin painting regimen. Compound A was a strong initiator and a weak carcinogen, and compound C was a strong promotor and a moderate carcinogen, whereas compound E did not have any effect. The NO2 group at the 2 position on the molecule was concluded to be responsible for the carcinogenic activity of the former two naphthofurans.

Cytotoxic potential of ketonucleosides.

The relationship between the structure of ketonucleosides and cytotoxicity was investigated in Friend leukemia cells (FLC). When cells were grown in the continuous presence of ketonucleosides, it was shown that the addition of an electrophilic agent (Br-) to the sugar moiety (compound KN-35) increased the cytotoxic potential by ten fold as compared to the unsubstitute compound (KN-43). In contrast, addition of 0-acetyl group (compound KN-3) reduced this effect by three fold.

Morphological transformation in three mammalian cell systems following treatment with 6-nitrochrysene and 6-nitrobenzo[a]pyrene.

Two nitroaromatics, 6-nitrobenzo[a]pyrene (6-N-BaP) and 6-nitrochrysene (6-N-CRY), and the corresponding parent hydrocarbons, benzo[a]pyrene (BaP) and chrysene (CRY), were studied in in vitro transformation assays with Syrian hamster embryo (SHE) cells, BALB/3T3 and C3H10T1/2 mouse cell lines. The three cell systems showed different sensitivities to the transforming effects of the chemicals studied, SHE cells being the most efficient, followed by 3T3 cells and the last being C3H10T1/2 cells. In the SHE cell system all compounds were active.

Absence of genotoxic effects in cells exposed to four ketonucleoside derivatives.

The relationship between the structure and genotoxic potential of four new cytostatic compounds--the ketonucleosides KN-35, KN-43, KN-44 and KN-3--was investigated in short-term in vitro assays of hypoxanthine-guanine phosphoribosyl transferase locus mutation in V79 cells, induction of chromosomal aberrations and sister chromatid exchanges on human lymphocytes, induction of chromosomal aberrations and micronuclei in V79 cells, and transformation of Syrian hamster embryo cells. None of the ketonucleosides induced mutagenic effects in any of the assays. Their failure to exhibit significantly genotoxic activity may be ascribed to the probable absence of any reaction between these drugs and the cellular DNA, and indicates that they act by some other mechanism which probably differs from the one observed with alkylating or intercalating antitumoural agents.

In vitro and in vivo activity of 12-O-3-N-dansylamino TPA.

Dansyl-TPA, a fluorescent TPA analogue, which is a label with a high affinity for C3H/10T1/2 cells and induces 3H-choline release from these cells (Tran et al. Nouv. J.

Use of an orthogonal design method to study two-stage chemical carcinogenesis in BALB/3T3 cells.

An orthogonal design method was used to study two-stage chemical carcinogenesis in BALB/3T3 cells. Four factors were studied: different concentrations of the initiator N-methyl-N-nitro-N'-nitrosoguanidine (MNNG); different concentrations of the promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA); different concentrations of fetal calf serum (FCS) and different times at which TPA was added after cell initiation. From the results of three experiments designed by Table L9(3(4)), L8(2(7)) and L16(4(5)), 0.

Micronuclei in red blood cells of the newt Pleurodeles waltl after treatment with benzo(a)pyrene: dependence on dose, length of exposure, posttreatment time, and uptake of the drug.

Aquatic larvae of the newt Pleurodeles waltl were exposed to different concentrations of benzo(a)pyrene (BaP) for various lengths of time. Frequencies of micronuclei in circulating erythrocytes were determined at different times after termination of the treatment. The incidence of micronuclei in larvae kept for 8 days in BaP-containing water displayed a marked increase with dose up to 0.

Naphthofurans induced chromosomal aberrations detected in metaphase, anaphase and telophase V79 Chinese hamster cells.

The mutagenic activities of 5 newly synthesized naphthofurans were analysed in two in vitro cytogenetic assays: the metaphase chromosomal aberration assay and the anaphase telophase bridge-fragment assay. Both assays were conducted using V79 Chinese hamster cells. The compounds included: 2-nitro-7-methoxynaphtho[2,1-b]furan (A), 2-nitro-8-methoxynaphtho[2,1-b]furan (B), 2-nitro-naphtho[2,1-b]furan (C), 2-nitro-7-bromonaphtho[2,1-b]furan (D) and 7-methoxynaphtho[2,1-b]furan (E).

Characterization and identification of 6 mutagens in opium pyrolysates implicated in oesophageal cancer in Iran.

Previous epidemiological studies have indicated an association between the ingestion of opium pyrolysates, dietary deficiencies, and a high incidence of oesophageal cancer in subjects in north-east Iran. Laboratory studies have shown that pyrolysates of opium and particularly of morphine, a major opium alkaloid, are highly mutagenic in bacteria and induce sister-chromatid exchanges in mammalian cells after metabolic activation. We now report the ability of these pyrolysates to transform Syrian hamster embryo cells in culture and present some evidence for their carcinogenicity in mice and hamsters following topical, subcutaneous, intratracheal and intragastric administration.

The in vitro micronucleus assay for detection of cytogenetic effects induced by mutagen-carcinogens: comparison with the in vitro sister-chromatid exchange assay.

The sensitivity of a cytogenetic assay, as expressed by the in vitro induction of micronuclei (MN), was compared to the in vitro induction of sister-chromatid exchanges (SCEs). Chinese hamster lung (V79) cells were exposed to 3 known alkylating agents: methyl methanesulphonate (MMS), ethyl methanesulphonate (EMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and to 5 newly synthesized naphthofurans: 2-nitro-7-methoxynaphtho[2,1-b]furan (A), 2-nitro-8-methoxynaphtho[2,1-b]furan (B), 2-nitronaphtho[2,1-b]furan (C), 2-nitro-7-bromonaphtho[2,1-b]furan (D) and 7-methoxynaphtho[2,1-b]furan (E). The induction of MN only was also analysed after exposure of the cells to 4 alcohols: ethanol, methanol, butanol and propanol.