Genotoxic action of cycloplatam, a new platinum antitumor drug, on mammalian cells in vivo and in vitro

Characterization of the genotoxic profile of antineoplastic drugs using the cytokinesis-block micronucleus cytome assay

Since antineoplastic agents are frequently used in cancer therapy and able to affect the patient's DNA, it is important to know the genotoxic consequences on non-cancerous tissue. Therefore, we aimed to characterize the genotoxic profile of antineoplastic drugs belonging to different classes, using the cytokinesis-block micronucleus cytome assay in a human monocytic cell line (THP-1). All tested antineoplastic agents resulted in increased micronucleus formation. Exposure to anthracyclines led to an increased number of vacuolated cells and cell death, while for mitotic spindle inhibitors, (different stages of) cell death and an increased nuclear bud formation was observed. Alkylating agents induce a high proportion of vacuolated cells and increased nuclear bud formation. No striking differences of nuclear division index or nucleoplasmic bridge formation were observed between exposed and non-exposed cells. The here presented class-specific aberrations may facilitate interpretation of genotoxic aberrations when evaluating clinical samples from patients treated with these antineoplastic agents.

Antiproliferative and genotoxic potential of xanthen-3-one derivatives

Twelve previously synthesized, biologically active 2,6,7-trihydroxyxanthen-3-one derivatives were evaluated in vitro for antiproliferative activity. Compounds were screened against HeLa, SW620, HepG2 and A549 tumor cell lines. Compound with the trifluormethyl group on C-4' position of the phenyl ring showed the best inhibitory activity towards HeLa and A549 tumor cells with IC50 of 0.7 and 4.1 µmol L-1, resp. Compound with chlorine and fluorine substituents on aryl ring showed the best antiproliferative activity against SW620 with IC50 of 4.1 µmol L-1 and against HepG2 tumor cell line with IC50 of 4.2 µmol L-1. Analyses of cytotoxic and genotoxic potential of the trifluormethyl derivative were performed with cytokinesis-block micronucleus cytome assay in human lymphocyte culture and revealed no genotoxic and cytotoxic effects. The most potent compounds were subjected to molecular docking simulations in order to analyse bindings to molecular targets and, at the same time, further support the results of experimental cytotoxic tests. Docking studies showed sites of importance in forming hydrogen bonds of the most potent compounds with targets of interest.

Genotoxic and mutagenic studies of teratogens in developing rat and mouse

In this review, genotoxic and mutagenic effects of teratogenic chemical agents in both rat and mouse have been reviewed. Of these chemicals, 97 are drugs and 33 are pesticides or belong to other groups. Large literature searches were conducted to determine the effects of chemicals on chromosome abnormalities, sister chromatid exchanges, and micronucleus formation in experimental animals such as rats and mice. In addition, studies that include unscheduled DNA synthesis, DNA adduct formations, and gene mutations, which help to determine the genotoxicity or mutagenicity of chemicals, have been reviewed. It has been estimated that 46.87% of teratogenic drugs and 48.48% of teratogenic pesticides are positive in all tests. So, all of the teratogens involved in this group have genotoxic and mutagenic effects. On the other hand, 36.45% of the drugs and 21.21% of the pesticides have been found to give negative results in at least one test, with the majority of the tests giving positive results. However, only 4.16% of the drugs and 18.18% of the pesticides were determined to give negative results in the majority of the tests. Among tests with major negative results, 12.50% of the teratogenic drugs and 12.12% of the teratogenic pesticides were negative in all conducted tests.

Acute toxic and genotoxic activities of widely used cytostatic drugs in higher plants: Possible impact on the environment

Cytostatic drugs are highly toxic pharmaceuticals and it was repeatedly postulated that they may cause adverse effects in ecosystems. The acute toxic and genotoxic properties of these drugs have not been adequately investigated in higher plants so far; therefore, we studied the most widely used drugs (5-flurouracil, 5FU; etoposide, Et; cisplatin, CisPt; carboplatin, CaPt; vincristine sulfate, VinS and cyclophosphamide monohydrate, CP) in micronucleus (MN) assays with meiotic pollen tetrad cells of Tradescantia and with root cells from Allium cepa. MNi are formed as a consequence of chromosome breaks and aneuploidy. We monitored also the acute toxic properties of the drugs, i.e. inhibition of cell division (mitotic indices and retardation of root growth) in the latter species. All compounds caused in both indicator plants genotoxic effects. The order of genotoxic potencies expressed as NOELs in µM was CisPt (0.1)≥ Et (0.5)>CP (1.0)>CaPt (10)>5FU (30)>VinS (100) in Tradescantia. A similar order was seen in Allium MN but Et was less active (5.0µM). Four compounds caused alterations of the mitotic indices under the present conditions namely CisPt (0.5), Et (10.0), 5FU (10.0) and VinS (100). Inhibition of root growth decreased in the order CisPt (0.5)>Et (1.0)≥VinS (1.0)>5FU (5.0)>CaPt (33.0)>CP (>1000). Comparisons of the NOELs with the predicted environmental concentrations (PEC) show that the latter values are at least 5 orders of magnitude lower and indicate that it is unlikely that their release in the environment may cause adverse effects in higher plants. However, it is notable that the levels of both platinum compounds and of 5FU in hospital effluents may reach levels which may induce damage of the genetic material.

Assessment of anti-mutagenic, anti-histopathologic and antioxidant capacities of Egyptian bee pollen and propolis extracts

Bee pollen and propolis are popular, traditional health foods. The objective of the current study was to investigate the anti-mutagenic, anti-histopathologic and antioxidant effects among water extracts of Egyptian bee pollen (WEBP) and brown powder of water-soluble derivative propolis (WSDP) on cisplatin (CDDP) induced hepatic, renal, testicular and genotoxicity in male albino mice (Mus muscullus), in addition to their effects on the oxidant/antioxidant status in the tested organs. Hepatic, renal and testicular dysfunctions were evaluated histologically; while genotoxicity and cytotoxicity were evaluated by the bone marrow chromosomal aberration assay and mitotic index, respectively. Moreover, oxidative stress was explored via determination of lipid peroxidation, catalase activity and the concentration of the reduced form of glutathione. The treatment of mice with WEBP and WSDP at doses 140 and 8.4 mg/kg b. wt./day, respectively for 14 days simultaneously with CDDP (2.8 mg/kg b. wt.) resulted in significant protection. The positive control animals taken CDDP alone showed toxic histological and genetical manifestations (at P < 0.05) accompanied with an elevated content of peroxidized lipid and lowered catalase activity and glutathione concentration in the homogenate of liver, kidney and testis tissues (at P < 0.001). These toxic side effects in all tested organs were greatly ablated with a significant reduction in lipid peroxidation level and elevation in catalase activity and glutathione concentration (P < 0.001) when using both WEBP and WSDP. On the basis of the present assays, Bee pollen appears more potent in exerting an ameliorative effect and this effect was more pronounced in testis.

A core in vitro genotoxicity battery comprising the Ames test plus the in vitro micronucleus test is sufficient to detect rodent carcinogens and in vivo genotoxins

In vitro genotoxicity testing needs to include tests in both bacterial and mammalian cells, and be able to detect gene mutations, chromosomal damage and aneuploidy. This may be achieved by a combination of the Ames test (detects gene mutations) and the in vitro micronucleus test (MNvit), since the latter detects both chromosomal aberrations and aneuploidy. In this paper we therefore present an analysis of an existing database of rodent carcinogens and a new database of in vivo genotoxins in terms of the in vitro genotoxicity tests needed to detect their in vivo activity. Published in vitro data from at least one test system (most were from the Ames test) were available for 557 carcinogens and 405 in vivo genotoxins. Because there are fewer publications on the MNvit than for other mammalian cell tests, and because the concordance between the MNvit and the in vitro chromosomal aberration (CAvit) test is so high for clastogenic activity, positive results in the CAvit test were taken as indicative of a positive result in the MNvit where there were no, or only inadequate data for the latter. Also, because Hprt and Tk loci both detect gene-mutation activity, a positive Hprt test was taken as indicative of a mouse-lymphoma Tk assay (MLA)-positive, where there were no data for the latter. Almost all of the 962 rodent carcinogens and in vivo genotoxins were detected by an in vitro battery comprising Ames+MNvit. An additional 11 carcinogens and six in vivo genotoxins would apparently be detected by the MLA, but many of these had not been tested in the MNvit or CAvit tests. Only four chemicals emerge as potentially being more readily detected in MLA than in Ames+MNvit--benzyl acetate, toluene, morphine and thiabendazole--and none of these are convincing cases to argue for the inclusion of the MLA in addition to Ames+MNvit. Thus, there is no convincing evidence that any genotoxic rodent carcinogens or in vivo genotoxins would remain undetected in an in vitro test battery consisting of Ames+MNvit.

In vitro antitumor activity of 2-acetyl pyridine 4n-ethyl thiosemicarbazone and its platinum(II) and palladium(II) complexes

The reaction of platinum(II) [Pt(II)] or palladium(II) [Pd(II)] with 2-acetyl pyridine 4N-ethyl thiosemicarbazone, HAc4Et (1) results in the complexes [Pt(Ac4Et)(2)] (2) and [Pd(Ac4Et)(2)] (3). In a panel of human tumor cell lines of different origins (breast, colon, and ovary cancers), and containing also cisplatin-refractory/resistant cell lines, the in vitro growth inhibitory effect of 1-3 was compared to that of cisplatin by using the sulforodamine B assay. After a 96-hour continuous treatment, both the thiosemicarbazone HAc4Et and the metal compounds [Pt(Ac4Et)(2)] and [Pd(Ac4Et)(2)] exhibit very remarkable growth inhibitory activities with mean IC(50) values of 0.9 nM (0.22-2.47 nM), 0.7 nM (0.15-2 nM) and 0.5 nM (0.17-1.02 nM), respectively. In contrast, cisplatin shows a markedly lower growth inhibitory potency, the mean IC(50) in the panel being 2.8 muM (0.2-8 muM). In addition to their major cell growth inhibitory potency, complexes 1-3 are characterized by a growth inhibitory profile different from that of cisplatin, being active towards cisplatin-refractory tumor cell lines. These findings, along with the ability of completely overcoming acquired cisplatin resistance from either multifocal or reduced uptake origin, confirm the antitumor potential of HAc4Et and support the hypothesis that both [Pt(Ac4Et)(2)] and [Pd(Ac4Et)(2)] complexes can be characterized by cellular pharmacological properties distinctly different from those of cisplatin.

Cytogenetic toxicity of cycloplatam in human lymphocytes: detection by the micronucleus test and fluorescence in situ hybridization

Cycloplatam has been shown to be effective in the treatment of pleural mesothelioma, myeloma and ovarian carcinoma. Cycloplatam is not nephrotoxic with respect to the platinum-based anti-tumor agents. We have investigated the mechanism underlying the induction of micronuclei (MN) in human lymphocytes by cycloplatam compared to that by its parent drugs cisplatin and carboplatin. The cytokinesis-block micronucleus assay in human lymphocytes was applied in combination with fluorescence in situ hybridization (FISH) with an all-chromosome centromeric probe allowing discrimination between MN due to chromosomal fragments (centromere negative, C) and those containing whole chromosomes (centromere positive, C). A statistically significant increase of MN frequency (P<0.001) was detected for cisplatin, carboplatin and cycloplatam. However, cycloplatam was active at a much lower dose (0.1 micromol/l) than cisplatin or carboplatin (1 micromol/l). No significant increase in the frequency of C or C MN was observed for cisplatin and carboplatin compared to the controls. A statistically significant (P<0.001) increase in the percentage of C MN was observed in cycloplatam-treated cells. The results obtained suggest different mechanisms for cytogenetic damage induced by platinum drugs. Cycloplatam induces one type of MN and it could be considered a clastogenic agent, whereas cisplatin and carboplatin appear to induce both chromosome breakage and numerical chromosomal abnormalities.