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Extracellular vesicles (EVs) are released from cells and enter into body fluids thereby providing a toxicological mechanism of cell-cell communication. The present study aimed at assessing (a) the presence of EVs in mouse body fluids under physiological conditions, (b) the effect of exposure of mice to cigarette smoke for 8 weeks, and (c) modulation of smoke-related alterations by the nonsteroidal anti-inflammatory drug celecoxib, a selective cyclooxygenase-2 inhibitor. To this purpose, ICR (CD-1) mice were either unexposed or exposed to cigarette smoke, either treated or untreated with oral celecoxib. EVs, isolated from bronchoalveolar lavage fluid (BALF), blood serum, and urines, were analyzed by nanoparticle tracking analysis and flow cytometry. EVs baseline concentrations in BALF were remarkably high. Larger EVs were detected in urines. Smoking increased EVs concentrations but only in BALF. Celecoxib remarkably increased EVs concentrations in the blood serum of both male and female smoking mice. The concentration of EVs positive for EpCAM, a mediator of cell-cell adhesion in epithelia playing a role in tumorigenesis, was much higher in urines than in BALF, and celecoxib significantly decreased their concentration. Thus, the effects of smoke on EVs concentrations were well detectable in the extracellular environment of the respiratory tract, where they could behave as delivery carriers to target cells. Celecoxib exerted both protective mechanisms in the urinary tract and adverse systemic effects of likely hepatotoxic origin in smoke-exposed mice. Detection of EVs in body fluids may provide an early diagnostic tool and an end-point exploitable for preventive medicine strategies., Journal of Preventive Medicine and Hygiene, Vol 60 No 4 (2019): 2019604

Carcinogenesis can be visualized either as a multistep process (initiation, promotion, progression, invasion, and metastasis) or as a continuum of mutagenic and mitogenic events, with the contribution of epigenetic mechanisms. The exponential growth of the neoplastic mass explains the importance of secondary prevention (early diagnosis) and of tertiary prevention. Primary prevention, which was successful in controlling occupational cancers, aims at minimizing exposures to carcinogens in healthy subjects and at favoring the intake of chemopreventive agents with dietary and pharmacological agents. Besides chemical carcinogens, often in the form of complex mixtures, the workplace may involve exposures to physical agents, such as sunlight and artificial illumination systems delivering UV radiation, or to biological agents, such as chronic viral infections (HBV, HCV, and HIV) associated with cancers. A controversial issue is the occurrence of threshold doses for carcinogens in the workplace and the environment.

N-Acetylcysteine (NAC) is a drug bearing multiple preventive properties that can inhibit genotoxicity and carcinogenicity. NAC also inhibits invasion and metastasis of malignant cells, as well as tumor take. We recently demonstrated the effects of NAC on Kaposi's sarcoma cells supernatant-induced invasion in vitro and angiogenesis in vivo. Many anticancer agents act through cytotoxicity of rapidly proliferating cells and several antineoplastic drugs induce apoptosis of cancer cells. Since endothelial cells are the target for the inhibition of angiogenesis, we wanted to verify that NAC, while inhibiting tumor vascularization and endothelial cell invasion would not induce endothelial cell apoptosis. We tested the ability of NAC to modulate apoptosis and cytogenetic damage in vitro and to promote differentiation on a reconstituted basement membrane (matrigel) in two endothelial cell lines (EAhy926 and HUVE). Treatment with NAC protected endothelial cells from TGF-beta-induced apoptosis and paraquat-induced cytogenetic damage. Therefore, NAC acts as an antiangiogenic agent and, at the same time, appears to prevent apoptosis and oxygen-related genotoxicity in endothelial cells.

7,12-Dimethylbenz(a)anthracene (DMBA) is a prototype carcinogen that induces a high yield of mammary tumors in rats after a single feeding. We investigated the induction and chemoprevention of DNA adducts in female Sprague Dawley rats receiving DMBA by gavage according to a variety of treatment schedules. The patterns of 32P-postlabeled DNA adducts in liver and mammary epithelial cells were similar to those produced by the in vitro reaction of metabolically activated DMBA with calf thymus DNA. There was a high and statistically significant correlation between dose of DMBA administered to rats (0, 0.6, 2.4, and 12 mg/kg body weight) and levels of DNA adducts in both types of cells. The regression lines relating DMBA doses to total DNA adduct levels were significantly divergent and crossed at 1.5 mg/kg body weight, indicating that, at lower doses, the formation of DNA adducts is more intense in target mammary cells, whereas at higher doses, DNA adduct levels are more elevated in liver cells, presumably due to the greater metabolic capacity of this organ. When the rats were sacrificed 7 days rather than 2 days after DMBA administration, DNA adduct levels were approximately halved in both liver and mammary cells. The observed patterns can be interpreted based on toxicokinetic factors, local and distant metabolism, removal of DNA adducts by excision repair, and cell proliferation rate. Of three chemopreventive agents given with the diet to rats treated with 12 mg of DMBA, 5,6-benzoflavone (1650 ppm) was the most effective, inhibiting DNA adduct formation in liver and mammary cells by 96.5 and 83.5%, respectively. Feeding of 1,2-dithiole-3-thione (600 ppm) inhibited this biomarker by 68.5 and 50.2%, whereas butyl hydroxyanisole (BHA; 5000 ppm) showed a significant inhibition in the liver (46.5%) but was ineffective in mammary cells (29.0%, not significant). These data correlate nicely with the results of a parallel study in which 5,6-benzoflavone, 1,2-dithiole-3-thione, and BHA inhibited formation of hemoglobin adducts by 80.0, 44.0, and 0%, respectively; the incidence of mammary tumors by 82.4, 47.1, and 5.9%, respectively; and their multiplicity by 92.6, 80.0, and 7.4%, respectively. Therefore, biomarkers of biologically effective dose are highly predictive of the efficacy of chemopreventive agents in the DMBA rat mammary model. The selective inhibition by BHA of DNA adducts in the liver but not in mammary cells is consistent with the finding that this phenolic antioxidant stimulated phase II activities in the liver but not in the mammary gland (L. L. Song et al., manuscript in preparation). In any case, the broad-spectrum inducer 5,6-BF appears to be more effective than the two monofunctional phase II inducers, presumably because an enhanced activation of DMBA to reactive metabolites is coordinated with their blocking, detoxification, and excretion.

Damage to mitochondrial DNA (mtDNA) has been postulated to be associated with aging, cancer, and other chronic degenerative diseases which are the predominant causes of death in the population. We used molecular dosimetry techniques, i.e., 32P postlabeling and synchronous fluorescence spectrophotometry, in order to evaluate the formation of adducts to both mtDNA and nuclear DNA (nDNA) in different organs of rats exposed to genotoxic carcinogens. Adducts to mtDNA were detected following administration of benzo(a)pyrene i.p. or 2-acetylaminofluorene by gavage as well as following exposure of animals to cigarette smoke. mtDNA adduct levels were consistently higher than those to nDNA in the same cells, and qualitative differences were also pointed out in the case of the aromatic amine. The oral administration of the thiol N-acetylcysteine, one of the most promising cancer chemopreventive agents endowed with nucleophilic and antioxidant properties, produced a significant decrease of mtDNA adducts in the liver of 2-acetylaminofluorene-treated rats and, sharply, in the lung and liver of rats exposed to cigarette smoke.

Since somatic mutations are suspected to contribute to the pathogenesis not only of cancer but also of atherosclerotic plaques, we measured DNA adducts in the smooth muscle layer of atherosclerotic lesions in abdominal aorta specimens taken at surgery from seven patients. DNA adducts were evaluated in three laboratories by means of different molecular dosimetry methods, including: (a) HPLC/fluorescence, which specifically identifies the DNA adducts of the anti-benzo(a)pyrene (BPDE) isomer; (b) two- and three-dimensional synchronous fluorescence spectrophotometries, which detect DNA adducts of BPDE and other reactive metabolites of polycyclic aromatic hydrocarbons; and (c) 32P postlabeling, which reveals the presence of a variety of types of DNA adducts. The HPLC/fluorescence method provided for the first time evidence for the presence of BPDE-DNA specific adducts in three of six specimens tested. Synchronous fluorescence spectrophotometry displayed broad areas of fluorescence in all seven specimens, thereby suggesting the occurrence not only of BDPE-DNA but also of other DNA adducts with similar fluorescence characteristics. All specimens were also positive at 32P postlabeling, which revealed multiple spots detectable following enrichment either with nuclease P1 or butanol, indicative of the presence of different aromatic DNA adducts. Thus, the data obtained by applying typical cancer biomarkers provide further support to the hypothesis that there may be similarities between the carcinogenic and the atherogenic processes, and in particular that genetic alterations caused by DNA-binding agents in the artery wall may be detected in atherosclerotic lesions.