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F D'Agostini

Publications and source records attributed to F D'Agostini.

At least 19 recordsLinked to original sources
PubMed2001

Inhibition of angiogenesis-driven Kaposi's sarcoma tumor growth in nude mice by oral N-acetylcysteine.

The thiol N-acetyl-L-cysteine (NAC), an analogue and precursor of reduced glutathione, has cancer chemopreventive properties attributable to its nucleophilicity, antioxidant activity, and a variety of other mechanisms. We demonstrated recently that NAC has anti-invasive, antimetastatic, and antiangiogenic effects in in vitro and in vivo test systems. In the present study, s.c. transplantation of KS-Imm cells in (CD-1)BR nude mice resulted in the local growth of Kaposi's sarcoma, a highly vascularized human tumor. The daily administration of NAC with drinking water, initiated after the tumor mass had become established and detectable, produced a sharp inhibition of tumor growth, with regression of tumors in half of the treated mice along with a markedly prolonged median survival time. The production of vascular endothelial growth factor (VEGF) and certain proliferation markers (proliferating cell nuclear antigen and Ki-67) were significantly lower in Kaposi's sarcomas from NAC-treated mice than from control mice. Treatment of KS-Imm cells with NAC in vitro resulted in a dose-dependent inhibition of chemotaxis and invasion through inhibition of gelatinase-A (matrix metalloproteinase-2, MMP-2) activity without altering MMP-2 or MMP-9 mRNA levels. NAC also significantly inhibited VEGF production but did not affect proliferation markers in vitro. Reverse transcription-PCR analysis indicated that total VEGF mRNAs were reduced by 10 mM NAC. Taken together, these findings provide evidence that NAC, the safety of which even at high doses has been established in almost 40 years of clinical use, in addition to its chemopreventive action, has a strong antiangiogenic potential that could be exploited for preventing cancer progression as well as used in cancer adjuvant therapy.

Acetylcysteine↗
PubMed2001

Multiple points of intervention in the prevention of cancer and other mutation-related diseases.

Multiple points of intervention are the target for dietary and pharmacological interventions aimed at preventing cancer and other diseases in which mutations in somatic cells play a pathogenetic role. For instance, our studies showed that DNA adducts can be consistently detected in arterial smooth muscle cells from human atherosclerotic lesions. Their levels were significantly correlated with the occurrence of atherogenic risk factors known from traditional epidemiology and were strikingly enhanced in atherosclerotic patients lacking the GSTM1 genotype. Cancer chemoprevention has a dual goal, i.e. prevention of occurrence of the disease (primary prevention) and early detection and reversion of tumors at a premalignant stage (secondary prevention). At a later stage, attempts can be made to prevent local recurrences as well as invasion and metastasis of malignant cells (tertiary prevention). For a rational use of chemopreventive agents it is essential not only to evaluate their efficacy and safety but also to understand the mechanisms involved. Sometimes it is difficult to discriminate whether modulation of a given end-point is actually a specific mechanism or rather the epiphenomenon of other events. For instance, we recently found that apoptosis is considerably stimulated in the respiratory tract of smoke-exposed rats; whereas certain chemopreventive agents work by further enhancing smoke-related apoptosis, other agents appear to downregulate apoptosis simply because they inhibit the genotoxic events signaling this process. We propose here a detailed, updated classification of the points of intervention exploitable in the prevention of mutation and cancer. The general outline includes a variety of extracellular and cellular mechanisms modulating the genotoxic response and tumor initiation as well as tumor promotion, progression, angiogenesis, invasion, and metastasis. This classification is not intended to provide a rigid scheme, since several intervention points are reiterated several times over different phases of the process. Moreover, some mechanisms are strictly interconnected or partially overlapping. Interestingly, a number of chemopreventive agents work through multiple mechanisms, which warrants a higher efficacy and a broader spectrum of action. It is also convenient to combine chemopreventive agents working through complementary mechanisms. In recent preclinical studies, we observed that combination of N-acetylcysteine with either oltipraz or ascorbic acid produces additive or more than additive protective effects towards early biomarkers and/or experimentally-induced tumors.

Animals↗
PubMed2001

Modulation of apoptosis by cigarette smoke and cancer chemopreventive agents in the respiratory tract of rats.

Preclinical studies may elucidate the meaning of biomarkers applicable to epidemiologic studies and to clinical trials for cancer prevention. No study has explored so far the effect of cigarette smoke on apoptosis in vivo. We evaluated modulation of apoptosis in cells of the respiratory tract of smoke-exposed Sprague-Dawley rats both by morphological analysis and TUNEL method. In a first study, exposure of rats to mainstream cigarette smoke for either 18 or 100 consecutive days produced a significant and time-dependent increase in the proportion of apoptotic cells in the bronchial and bronchiolar epithelium. Oral N:-acetylcysteine did not affect the background frequency of apoptosis but significantly and sharply decreased smoke-induced apoptosis. In a second study, exposure of rats to a mixture of sidestream and mainstream smoke for 28 consecutive days resulted in a >10-fold increase in the frequency of pulmonary alveolar macrophages undergoing apoptosis. Dietary administration of either 5,6-benzoflavone, 1,2-dithiole-3-thione or oltipraz did not affect the frequency of smoke-induced apoptosis, whereas phenethyl isothiocyanate produced a further significant enhancement. Again, N-acetylcysteine and its combination with oltipraz significantly decreased smoke-induced apoptosis. In both studies exposure to smoke resulted in a sharp increase of cells positive for proliferating cell nuclear antigen (PCNA), which was unaffected by the examined chemopreventive agents. These findings highlight the concept that modulation of apoptosis has diversified meanings. Different meanings (as explained in the following lines). First, the apoptotic process is triggered as a defense system against genotoxic agents, such as the components of cigarette smoke. The further induction produced by phenethyl isothiocyanate, favoring removal of damaged cells, represents an example of a detoxification mechanism. Inhibition of smoke-induced apoptosis by N:-acetylcysteine should be interpreted as an epiphenomenon of antigenotoxic mechanisms, as shown in parallel studies evaluating modulation of DNA alterations in the respiratory tract of the same animals. Thus, it is important to discriminate between whether the opposite modulation of apoptosis is per se a protective mechanism or the beneficial outcome of other mechanisms inhibiting genotoxicity.

Animals↗
PubMed2001

Mechanisms of N-acetylcysteine in the prevention of DNA damage and cancer, with special reference to smoking-related end-points.

Although smoking cessation is the primary goal for the control of cancer and other smoking-related diseases, chemoprevention provides a complementary approach applicable to high risk individuals such as current smokers and ex-smokers. The thiol N-acetylcysteine (NAC) works per se in the extracellular environment, and is a precursor of intracellular cysteine and glutathione (GSH). Almost 40 years of experience in the prophylaxis and therapy of a variety of clinical conditions, mostly involving GSH depletion and alterations of the redox status, have established the safety of this drug, even at very high doses and for long-term treatments. A number of studies performed since 1984 have indicated that NAC has the potential to prevent cancer and other mutation-related diseases. N-Acetylcysteine has an impressive array of mechanisms and protective effects towards DNA damage and carcinogenesis, which are related to its nucleophilicity, antioxidant activity, modulation of metabolism, effects in mitochondria, decrease of the biologically effective dose of carcinogens, modulation of DNA repair, inhibition of genotoxicity and cell transformation, modulation of gene expression and signal transduction pathways, regulation of cell survival and apoptosis, anti-inflammatory activity, anti-angiogenetic activity, immunological effects, inhibition of progression to malignancy, influence on cell cycle progression, inhibition of pre-neoplastic and neoplastic lesions, inhibition of invasion and metastasis, and protection towards adverse effects of other chemopreventive agents or chemotherapeutical agents. These mechanisms are herein reviewed and commented on with special reference to smoking-related end-points, as evaluated in in vitro test systems, experimental animals and clinical trials. It is important that all protective effects of NAC were observed under a range of conditions produced by a variety of treatments or imbalances of homeostasis. However, our recent data show that, at least in mouse lung, under physiological conditions NAC does not alter per se the expression of multiple genes detected by cDNA array technology. On the whole, there is overwhelming evidence that NAC has the ability to modulate a variety of DNA damage- and cancer-related end-points.

Acetylcysteine↗
PubMed2001

Pilot studies evaluating the lung tumor yield in cigarette smoke-exposed mice.

In spite of the major role played by cigarette smoking in the epidemiology of lung cancer, it is very difficult to reproduce the carcinogenicity of this complex mixture in animal models. We implemented a series of pilot experiments in three mouse strains, exposed either to environmental cigarette smoke (ECS) or mainstream cigarette smoke (MCS) or its condensate (MCSC). The whole-body exposure of Aroclor-treated A/J mice to ECS resulted in a rapid and potent induction of micronuclei in peripheral blood erythrocytes. After 6 months of exposure, 6 h a day, followed by 4 months of recovery in filtered air, both lung tumor incidence and multiplicity were significantly increased as compared to sham-exposed mice (77.8% vs. 22.2%, and 1.11+/-0.26 vs. 0.22+/-0.15, means +/- SE). Multiple i.p. injections of butylated hydroxytoluene did not significantly enhance the tumor yield. Another experiment confirmed the responsiveness of A/J mice exposed to ECS for 5 months, followed by 4 months of recovery in air (75.0% vs. 25.0%, and 1.05+/-0.17 vs. 0.25+/-0.10). In contrast, the increase in lung tumor yield after exposure to ECS for 2 months, followed by recovery in air for 7 months, was not significant, and the continuous exposure to ECS for 9 months was totally ineffective. These data, in agreement with previous results of others, show that exposure of A/J mice to ECS for 5-6 months, followed by recovery in air for 4 months, is successful in inducing a weak but significant and reproducible increase in lung tumor yield. Furthermore, the simultaneous exposure to the light emitted by halogen quartz bulbs for 9 months and to ECS for 5 months, followed by 4 months in air, was again weakly tumorigenic (incidence of 55.0% and multiplicity of 0.75+/-0.19), whereas exposure to both ECS and light for 9 months was devoid of effect. The whole-body exposure of A/J mice to MCS, 1 h a day for 5 months, or weekly i.p. injections of MCSC for 5 months, followed in both cases by 4 months of recovery in air, failed to enhance the lung tumor yield. The whole-body exposure of SKH-1 hairless mice to ECS for 6 months, followed by exposure to halogen light for 8 months, resulted in the formation of multiple skin tumors but failed to produce lung tumors. The whole-body exposure of C57BL/6 mice to ECS for 6 months failed to induce any lung tumor but caused alopecia, gray hair, and hair bulb cell apoptosis, which were prevented by the oral administration of N-acetylcysteine.

Acetylcysteine↗
PubMed2000

Interactions between N-acetylcysteine and ascorbic acid in modulating mutagenesis and carcinogenesis.

Both ascorbic acid (AsA, vitamin C) and N-acetylcysteine (NAC), a precursor and analogue of glutathione, possess a broad array of biological properties underlying their protective role in a variety of pathophysiological conditions. However, under certain circumstances, AsA behaves as a pro-oxidant rather than an anti-oxidant and produces adverse effects. This prompted us to evaluate whether NAC could interact with AsA in preventing mutation and cancer. AsA significantly increased spontaneous revertants in the Salmonella typhimurium strains TA102 and TA104, which are sensitive to oxidative mutagens. In contrast, NAC lowered the spontaneous background in TA104 and neutralized the negative effects of AsA. Moreover, NAC and AsA showed additive effects in reducing chromium(VI) and in reverting its mutagenicity. A single i.p. injection of urethane (1 g/kg body weight) to 120 A/J mice resulted, after 4 months, in the formation of a total of 1,532 lung tumors, 425 in the 30 mice treated with the carcinogen only, 404 in those treated with urethane plus AsA, 365 in those treated with urethane plus NAC and 338 in those treated with urethane plus the combination of AsA and NAC (both given daily with drinking water at the dose of 1 g/kg body weight). Compared to positive controls, tumor multiplicity was poorly affected by AsA, whereas it was significantly decreased by NAC and even more so by its combination with AsA. The overall volumes of lung tumors in the 4 groups were 107.5, 89.3, 61.3 and 49.7 mm(3), respectively. Tumor sizes were slightly but significantly decreased in mice treated with AsA and more so in those treated with NAC and NAC plus AsA, their combination being significantly more effective than each individually. All protective effects elicited by combining the 2 drugs were additive. Therefore, NAC prevents the adverse effects of AsA on spontaneous mutagenicity; at the same time, this thiol behaves in an additive fashion with AsA, inhibiting the mutagenicity of chromium(VI) and the lung tumorigenicity of urethane in mice. These findings suggest that NAC and AsA could conveniently be combined in cancer chemoprevention and other pharmacological interventions.

Acetylcysteine↗
PubMed2000

Induction of alopecia in mice exposed to cigarette smoke.

Besides being responsible for a high proportion of those chronic degenerative diseases that are the leading causes of death in the population, tobacco smoking has been associated with skin diseases. Smoke genotoxicants are metabolized in hair follicle cells, where they form DNA adducts and cause DNA damage. The suspicion was raised that, in humans, a link may exist between smoking and both premature grey hair and hair loss. In order to check this hypothesis, we carried out a study in C57BL/6 mice exposed whole-body to a mixture of sidestream and mainstream cigarette smoke. After 3 months exposure, most mice developed areas of alopecia and grey hair, while no such lesions occurred either in sham-exposed mice or in smoke-exposed mice receiving the chemopreventive agent N-acetylcysteine with drinking water. Cell apoptosis occurred massively in the hair bulbs at the edge of alopecia areas. Smoke-exposed mice had extensive atrophy of the epidermis, reduced thickness of the subcutaneous tissue, and scarcity of hair follicles. On the whole, exposure to smoke genotoxic components appears to alter the hair cycle with a dystrophic anagen pattern. Although this mechanism is different from that of genotoxic cytostatic drugs, N-acetylcysteine appears to exert protective effects in both conditions.

Acetylcysteine↗
PubMed2000

Less than additive interaction between cigarette smoke and chromium(VI) in inducing clastogenic damage in rodents.

A combination of tobacco smoking with certain agents has been shown to exert synergistic carcinogenic effects. On the other hand, antagonism betweeen smoke and other pulmonary carcinogens has also been documented by both epidemiological and experimental data. In spite of a very large number of studies carried out for decades in workers exposed to hexavalent chromium, the influence of smoking habits on lung carcinogenesis induced by this metal has not been clarified. For this reason, we performed two studies evaluating clastogenic effects in rodents. In the first one, BDF(1) mice were exposed whole-body to mainstream cigarette smoke for 5 days and, on the last day, they received an i.p. injection of potassium dichromate. In the second study, Sprague-Dawley rats were exposed whole-body to environmental cigarette smoke for 18 consecutive days and for the same period of time they received daily intra-tracheal instillations of sodium dichromate. Individually, the two hexavalent chromium salts and cigarette smoke, either mainstream or environmental, enhanced the frequency of micronuclei in bone marrow polychromatic erythrocytes of both mice and rats. Moreover, individual exposure to either environmental cigarette smoke or sodium dichromate enhanced the frequency of micronuclei and multiple nuclei in pulmonary alveolar macrophages of rats. In both studies, combined exposure to cigarette smoke and hexavalent chromium produced less than additive clastogenic effects. These results are consistent with our previous data, showing that hexavalent chromium and either benzo[a]pyrene or cigarette smoke condensate behave antagonistically in in vitro mutagenicity test systems and that the chromium reducing capacity of human pulmonary alveolar macrophages and peripheral lung parenchyma is enhanced in smokers. Taken together, in the absence of any epidemiological evidence, these findings rule out any occurrence of synergism between cigarette smoke and hexavalent chromium, at least in certain stages of the carcinogenesis process.

Animals↗
PubMed1999

Formation and persistence of nucleotide alterations in rats exposed whole-body to environmental cigarette smoke.

The assessment of pathological effects produced by environmental tobacco smoke in humans is controversial in epidemiological studies. On the other hand, animal models are poorly sensitive to smoke carcinogenicity. We designed an experimental study assessing the tissueselective formation and persistence of DNA adducts in smoke-exposed rats. Sprague-Dawley rats were exposed for 6 h per day, 5 days per week, to environmental smoke resulting from a mixture of sidestream and mainstream smoke generated from Kentucky 2R1 reference cigarettes. The total particulate matter was in the range of 73-93 mg/m(3). DNA adducts were measured by (32)P-post-labelling in rat organs (lung, heart, liver, bladder and testis), tissues (dissected tracheal epithelium) and cells [isolated bronchoalveolar lavage (BAL) cells]. A time-related increase of (32)P-post-labelled DNA modifications was detectable by autoradiography, in the form of massive diagonal radioactive zones and individual spots. Top levels were reached after 4-5 weeks of exposure. The ratio of smoke-induced DNA adducts to the background levels detected in sham-exposed rats was 11.2 in the tracheal epithelium, 10.4 in BAL cells, 7.3 in the heart, 6.3 in the lung, 5.1 in the bladder, 1.9 in the testis and 1. 1 in the liver. Appearance of DNA adducts in the lung was also revealed by synchronous fluorescence spectrophotometry. Smoke-related oxidative damage was demonstrated by a significant enhancement of 8-hydroxy-2'-deoxyguanosine in lung DNA. In parallel, there was a time-related induction of lung microsomal arylhydrocarbon hydroxylase activity, an elevation in cytosolic glutathione S-transferase activity, and a moderate but progressive and significant depletion of reduced glutathione. After discontinuing exposure to environmental cigarette smoke for 1 week, DNA adduct levels significantly dropped in the lung, tracheal epithelium, heart and bladder. The decrease was evident but not statistically significant in BAL cells, and was negligible in the heart. The selective localization and the differential persistence of these promutagenic nucleotide modifications in rat organs, tissues and cells suggest that exposure to environmental cigarette smoke, at least under the high exposure regimens used in experimental studies, may pose a potential risk of developing mutation-related diseases.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1999

Induction and prevention of micronuclei and chromosomal aberrations in cultured human lymphocytes exposed to the light of halogen tungsten lamps.

Previous studies have shown that the light emitted by halogen tungsten lamps contains UV radiation in the UV-A, UV-B and UV-C regions, induces mutations and irreparable DNA damage in bacteria, enhances the frequency of micronuclei in cultured human lymphocytes and is potently carcinogenic to the skin of hairless mice. The present study showed that the light emitted by an uncovered, traditional halogen lamp induces a significant, dose-related and time-related increase not only in micronuclei but also in chromosome-type aberrations, such as breaks, and even more in chromatid-type aberrations, such as isochromatid breaks, exchanges and isochromatid/chromatid interchanges, all including gaps or not, in cultured human lymphocytes. All these genotoxic effects were completely prevented by shielding the same lamp with a silica glass cover, blocking UV radiation. A new model of halogen lamp, having the quartz bulb treated in order to reduce the output of UV radiation, was considerably less genotoxic than the uncovered halogen lamp, yet induction of chromosomal alterations was observed at high illuminance levels.

Adult↗
PubMed1999

N-acetylcysteine inhibits endothelial cell invasion and angiogenesis.

The thiol N-acetylcysteine (NAC) is a chemopreventive agent that acts through a variety of mechanisms and can prevent in vivo carcinogenesis. We have previously shown that NAC inhibits invasion and metastasis of malignant cells as well as tumor take. Neovascularization is critical for tumor mass expansion and metastasis formation. We investigated whether a target of the anti-cancer activity of NAC could be the inhibition of the tumor angiogenesis-associated phenotype in vitro and in vivo using the potent angiogenic mixture of Kaposi's sarcoma cell products as a stimulus. Two endothelial (EAhy926 and human umbilical vein endothelial [HUVE]) cell lines were utilized in a panel of assays to test NAC ability in inhibiting chemotaxis, invasion, and gelatinolytic activity in vitro. NAC treatment of EAhy926 and HUVE cells in vitro dose-dependently reduced their ability to invade a reconstituted basement membrane, an indicator of endothelial cell activation. Invasion of HUVE cells was inhibited with an ID50 of 0.24 mM NAC, whereas inhibition of chemotaxis required a 10 fold higher doses, indicating that invasion is a preferential target. NAC inhibited the enzymatic activity and conversion to active forms of the gelatinase produced by endothelial cells. The matrigel in vivo assay was used for the evaluation of angiogenesis; NAC strongly inhibited neovascularization of the matrigel sponges in response to Kaposi's sarcoma cell products. NAC prevented angiogenesis while preserving endothelial cells, implying that it could be safely used as an anti-angiogenic treatment.

Acetylcysteine↗
PubMed1998

Inhibition by oral N-acetylcysteine of doxorubicin-induced clastogenicity and alopecia, and prevention of primary tumors and lung micrometastases in mice.

The thiol N-acetylcysteine (NAC), an analog and precursor of glutathione, displays cancer preventive properties not only in early stages of the carcinogenesis process but also in its advanced stages. NAC inhibited type-IV collagenase activity as well as invasion, tumor take, and metastasis of malignant cells in murine models. Previously, we provided evidence for synergistic effects of oral NAC with intravenously injected doxorubicin (DOX). In the present study B16-BL6 melanoma cells were injected s.c. into the footpad of C57BL/6 mice. The animals were divided into 5 groups: i) untreated mice; ii) mice receiving daily NAC with drinking water (12.25 mmol/kg body weight) starting 16 h after injection of cancer cells; iii) mice receiving a single i.v. injection of DOX (2 micromol/kg body weight) 24 h after injection of cancer cells; iv) mice receiving a combination of NAC and DOX, with NAC treatment starting 72 h before injection of cancer cells; and v) mice treated as in iv) but with NAC treatment starting 16 h after injection of cancer cells. Both NAC and DOX, either individually or in combination, significantly enhanced the survival time as compared to controls. The weight of local primary tumors was significantly decreased by either drug, and was further decreased to a significant extent, compared to the individual treatments, in the two groups of mice receiving combinations of NAC and DOX. No lung micrometastases, evaluated by immunohistochemistry as S-100-positive foci of melanocytic cells, were detectable in the two groups of mice receiving the combined treatments. NAC significantly, attenuated the time-related increase of micronucleated polychromatic erythrocytes in the peripheral blood of DOX-treated mice. All mice individually treated with DOX developed a partial but well evident alopecia, diffusely affecting their back hair, which was totally prevented by NAC, irrespective of the combination schedule. Thus, besides preventing DOX cardiotoxicity, as extensively documented in the literature, oral NAC protects mice from DOX-induced myelogenotoxicity and alopecia, and at the same time interacts with this cytotoxic agent in inhibiting cancer cell invasion and metastasis.

Acetylcysteine↗
PubMed1996

Synergism between N-acetylcysteine and doxorubicin in the prevention of tumorigenicity and metastasis in murine models.

The thiol N-acetylcysteine (NAC) is a promising cancer chemopreventive agent which acts through a variety of mechanisms, including its nucleophilic and antioxidant properties. We have recently shown that NAC inhibits type-IV collagenase activity as well as invasion, tumor take and metastasis of malignant cells in mice. NAC is also known to attenuate the cardiotoxicity of the cytostatic drug doxorubicin (DOX, Adriamycin). The present study was designed to evaluate whether the combination of NAC and DOX treatments in mice injected with cancer cells could affect their tumorigenic and metastatic properties. Six separate experiments were carried out, using a total of 291 adult female mice. In experimental metastasis assays, in which B16-F10 melanoma cells were injected i.v. into (CD-1)BR nude mice, DOX significantly reduced the number of lung metastases when administered i.v. at a dose of 10 mg/kg body weight, 3 days after the i.v. injection of cancer cells. NAC inhibited lung metastases when added to the medium of cancer cells before their i.v. injection. The combined treatment with DOX and NAC, under various experimental conditions, was highly effective, showing a synergistic reduction in the number of mestastases. In tumorigenicity and spontaneous metastasis assays, in which B16-BL6 melanoma cells were injected s.c. into the footpad of C57BL/6 mice, DOX decreased the number of lung metastases when given i.p. at 2 mg/kg body weight. Oral NAC exerted significant protective effects, and considerably prolonged survival of mice. The combined treatment with DOX and NAC again showed synergistic effects on the frequency and weight of primary tumors and local recurrences, and completely prevented the formation of lung metastases in the experiment in which these end-points were evaluated at fixed times. While injection of DOX 7 days after implantation of cancer cells failed to improve the cancer-protective effects of NAC, its injection after I day resulted in a striking inhibition of lung metastases. These findings demonstrate an evident synergism between DOX (given parenterally) and NAC (given with drinking water) in preventing tumorigenicity and metastases. The indications of these animal studies warrant further evaluation in clinical trials.

Acetylcysteine↗
PubMed1996

Biomarker alterations produced in rat lung by intratracheal instillations of air particulate extracts and chemoprevention with oral N-acetylcysteine.

Organic matter extracts were obtained from particulates recovered from 10,000-m3 air samples collected in Sicily (Italy). The overall concentrations of acenaphthene, benzo(a)pyrene, phenanthrene, anthracene, fluoranthene, and pyrene were 526 ng/m3 air in a highly polluted urban area and 48 ng/m3 in a rural area affected by motor vehicle traffic pollution. After metabolic activation, both samples were mutagenic in Salmonella typhimurium his(-) strains of the TA and YG series, with potencies in TA100 of 140.7 and 11.8 revertants/m3 air, respectively. The samples, resuspended in tricaprylin, were instilled intratracheally in Sprague-Dawley rats for 5 consecutive days, accounting for a cumulative dose in each animal of the organic fractions extracted from 400 m3 air, which corresponds approximately to the volume of air inhaled by a man in 1 month. Treatment with the rural area sample and, at higher levels, with the urban area sample resulted in the formation of adducts to lung DNA, as assessed both by synchronous fluorescence spectrophotometry and by 32P postlabeling, which showed the appearance of up to six individual adducts emerging from diffuse diagonal radioactive zones. The adducts were more efficiently detected by extraction with butanol than by digestion with nuclease P1. DNA binding of air particulate extracts was followed by alterations of early damage biomarkers only in the rats treated with the urban area sample. Repair of DNA damage in lung cells was inferred from a significant stimulation of the nuclear enzyme poly(ADP-ribose) polymerase compared with that in sham-exposed rats. Among the cells recovered by bronchoalveolar lavage, an increase in polymorphonucleate leukocytes and cells of the ciliated respiratory epithelium was accompanied by a relative decrease in pulmonary alveolar macrophages. The frequency of micronuclei was significantly enhanced both in epithelial cells and alveolar macrophages, and binucleated macrophages were also more frequent in treated rats. The thiol N-acetylcysteine, one of the most promising cancer chemopreventive agents, was administered with drinking water to a group of animals receiving the air particulate polycyclic aromatic hydrocarbon fraction from the urban area. N-acetylcysteine prevented or considerably attenuated the alterations of all monitored parameters. These findings provide evidence that, even under outstandingly high exposure conditions, it is possible to protect the respiratory tract from DNA-binding and DNA-damaging air particulate carcinogens.

Acetylcysteine↗
PubMed1996

Induction by carcinogens and chemoprevention by N-acetylcysteine of adducts to mitochondrial DNA in rat organs.

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.

2-Acetylaminofluorene↗
PubMed1996

Human antibodies against the polymorphic epithelial mucin in ovarian cancer patients recognise a novel sequence in the tandem repeat region.

The humoral immune response to the polymorphic epithelial mucin (PEM) was studied by characterising the reactivity of human antibodies generated by EBV-immortalised B-cells from tumour-draining lymph nodes of ovarian cancer patients. All the human antibodies, selected in ELISA for their reactivity to the protein tandem core repeat sequence, reacted with PEM-expressing tumour cells. Aberrant glycosylation of the peptide core of the PEM molecule in cancer cells leads to the exposure of peptide epitopes that can be considered tumour specific. The epitope mapping of six human antibodies revealed that only one of them contained the PDTR sequence, shown to be the immunodominant epitope in the mouse. Four of the six human antibodies recognised a novel common immunogenic sequence (APPAH) in the tandem repeats. The binding of these human antibodies did not appear to be modulated by the length of the carbohydrate side chains, as shown by O-glycosylation inhibition studies. These results indicate that distinct sequences within the tandem repeat of PEM are target for a humoral immune response in humans. The presence of antibodies directed against different epitopes within the same antigenic region may modulate the antigen presentation process and the ongoing immune response. This data may help in clarifying the mechanisms of the immune response to PEM in cancer patients for the development of PEM-based immunotherapy.

Antibodies, Neoplasm↗
PubMed1995

Inhibition of invasion, gelatinase activity, tumor take and metastasis of malignant cells by N-acetylcysteine.

The thiol N-acetylcysteine (NAC) is currently considered one of the most promising cancer chemopreventive agents by virtue of its multiple and coordinated mechanisms affecting the process of chemical carcinogenesis. Recent studies have shown that an unpaired cysteine residue in the propeptide plays a key role in inactivation of latent metastasis-associated metalloproteinases: the present study was designed to assess whether NAC could also affect tumor take, invasion and metastasis of malignant cells. As assessed by zymographic analysis, NAC completely inhibited the gelatinolytic activity of type-IV collagenases in the cells tested (gelatinases A and B). Moreover, NAC was efficient in inhibiting the chemotactic and invasive activities of tumor cells of human (A2058 melanoma) and murine origin (K1735 and B16-F10 melanoma cells as well as C87 Lewis lung carcinoma cells) in Boyden-chamber assays, which are predictive of the invasive and metastatic properties. Reduced glutathione (GSH) had a similar, although less effective activity. The number of lung metastases decreased sharply when B16-F10 murine melanoma cells, injected i.v. into nude mice, were pre-treated with NAC and resuspended in medium supplemented with 10 mM NAC. In other experiments NAC was given in drinking water, starting 48-72 hr before subcutaneous inoculation of either B16-F10 cells or of their highly metastatic variant B16-BL6, or intramuscular injection of LLC cells. In all experiments NAC treatment decreased the weight of the locally formed primary tumor and produced a dose-related delay in tumor formation. Spontaneous metastasis formation by B16-F10 and B16-BL6 tumors was slightly yet significantly reduced by oral administration of NAC. However, this was not observed for Lewis lung tumors. These data indicate that NAC affects the process of tumor-cell invasion and metastasis, probably due to inhibition of gelatinases by its sulfhydryl group, with the possible contribution of other mechanisms, including the potent antioxidant activity of this thiol.

3T3 Cells↗