Transgenerational inheritance of enhanced susceptibility to radiation-induced medulloblastoma in newborn Ptch1⁺/⁻ mice after paternal irradiation.

The hypothesis of transgenerational induction of increased cancer susceptibility after paternal radiation exposure has long been controversial because of inconsistent results and the lack of a mechanistic interpretation. Here, exploiting Ptch1 heterozygous knockout mice, susceptible to spontaneous and radiation-induced medulloblastoma, we show that exposure of paternal germ cells to 1 Gy X-rays, at the spermatogonial stage, increased by a considerable 1.4-fold the offspring susceptibility to medulloblastoma induced by neonatal irradiation. This effect gained further biological significance thanks to a number of supporting data on the immunohistochemical characterization of the target tissue and preneoplastic lesions (PNLs). These results altogether pointed to increased proliferation of cerebellar granule cell precursors and PNLs cells, which favoured the development of frank tumours. The LOH analysis of tumor DNA showed Ptch1 biallelic loss in all tumor samples, suggesting that mechanisms other than interstitial deletions, typical of radiation-induced medulloblastoma, did not account for the observed increased cancer risk. This data was supported by comet analysis showing no differences in DNA damage induction and repair in cerebellar cells as a function of paternal irradiation. Finally, we provide biological plausibility to our results offering evidence of a possible epigenetic mechanism of inheritance based on radiation-induced changes of the microRNA profile of paternal sperm.

Genomic and post-genomic effects of anti-glaucoma drugs preservatives in trabecular meshwork.

Oxidative stress plays an important role in glaucoma. Some preservatives of anti-glaucoma drugs, commonly used in glaucoma therapy, can prevent or induce oxidative stress in the trabecular meshwork. The aim of this study is to evaluate cellular and molecular damage induced in trabecular meshwork by preservatives contained in anti-glaucoma drugs. Cell viability (MTT test), DNA fragmentation (Comet test), oxidative DNA damage (8-oxo-dG), and gene expression (cDNA microarray) have been evaluated in trabecular meshwork specimens and in human trabecular meshwork cells treated with benzalkonium chloride, polyQuad, purite, and sofzia-like mixture. Moreover, antimicrobial effectiveness and safety of preservative contents in drugs was tested. In ex vivo experiments, benzalkonium chloride and polyQuad induced high level of DNA damage in trabecular meshwork specimens, while the effect of purite and sofzia were more attenuated. The level of DNA fragmentation induced by benzalkonium chloride was 2.4-fold higher in subjects older than 50 years than in younger subjects. Benzalkonium chloride, and polyQuad significantly increased oxidative DNA damage as compared to sham-treated specimens. Gene expression was altered by benzalkonium chloride, polyQuad, and purite but not by sofzia. In in vitro experiments, benzalkonium chloride and polyQuad dramatically decreased trabecular meshwork cell viability, increased DNA fragmentation, and altered gene expression. A lesser effect was also exerted by purite and sofzia. Genes targeted by these alterations included Fas and effector caspase-3. The efficacy of the preservatives in inhibiting bacterial growth increased the adverse effects in trabecular meshwork in terms of DNA damage and alteration of gene expression. Presented data indicates the delicate balance between efficacy and safety of drug preservatives as not yet optimized.

Modulation of cigarette smoke-related end-points in mutagenesis and carcinogenesis.

The epidemic of lung cancer and the increase of other tumours and chronic degenerative diseases associated with tobacco smoking have represented one of the most dramatic catastrophes of the 20th century. The control of this plague is one of the major challenges of preventive medicine for the next decades. The imperative goal is to refrain from smoking. However, chemoprevention by dietary and/or pharmacological agents provides a complementary strategy, which can be targeted not only to current smokers but also to former smokers and passive smokers. This article summarises the results of studies performed in our laboratories during the last 10 years, and provides new data generated in vitro, in experimental animals and in humans. We compared the ability of 63 putative chemopreventive agents to inhibit the bacterial mutagenicity of mainstream cigarette smoke. Modulation by ethanol and the mechanisms involved were also investigated both in vitro and in vivo. Several studies evaluated the effects of dietary chemopreventive agents towards smoke-related intermediate biomarkers in various cells, tissues and organs of rodents. The investigated end-points included metabolic parameters, adducts to haemoglobin, bulky adducts to nuclear DNA, oxidative DNA damage, adducts to mitochondrial DNA, apoptosis, cytogenetic damage in alveolar macrophages, bone marrow and peripheral blood erytrocytes, proliferation markers, and histopathological alterations. The agents tested in vivo included N-acetyl-L-cysteine, 1,2-dithiole-3-thione, oltipraz, phenethyl isothiocyanate, 5,6-benzoflavone, and sulindac. We started applying multigene expression analysis to chemoprevention research, and postulated that an optimal agent should not excessively alter per se the physiological background of gene expression but should be able to attenuate the alterations produced by cigarette smoke or other carcinogens. We are working to develop an animal model for the induction of lung tumours following exposure to cigarette smoke. The most encouraging results were so far obtained in models using A/J mice and Swiss albino mice. The same smoke-related biomarkers used in animal studies can conveniently be applied to human chemoprevention studies. We participated in trials evaluating the effects of N-acetyl-L-cysteine and oltipraz in smokers from Italy, The Netherlands, and the People's Republic of China. We are trying to develop a pharmacogenomic approach, e.g. based on genetic metabolic polymorphisms, aimed at predicting not only the risk of developing cancer but also the individual responsiveness to chemopreventive agents.