Lack of carcinogenicity and increased survival in F344 rats treated with 5-fluorouracil for two years

Molecular dynamics, density functional, ADMET predictions, virtual screening, and molecular interaction field studies for identification and evaluation of novel potential CDK2 inhibitors in cancer therapy

In this work, we have used molecular dynamics, density functional theory, virtual screening, ADMET predictions, and molecular interaction field studies to design and propose eight novel potential inhibitors of CDK2. The eight molecules proposed showed interesting structural characteristics that are required for inhibiting the CDK2 activity and show potential as drug candidates for the treatment of cancer. The parameters related to the Rule of Five were calculated, and only one of the molecules violated more than one parameter. One of the proposals and one of the drug-like compounds selected by virtual screening indicated to be promising candidates for CDK2-based cancer therapy.

SFTG international collaborative study on in vitro micronucleus test I. General conditions and overall conclusions of the study

This study, coordinated by the SFTG (French branch of European Environmental Mutagen Society), included 38 participants from Europe, Japan and America. Clastogens (bleomycin, urethane), including base and nucleoside analogs (5-fluorouracil and cytosine arabinoside), aneugens and/or polyploidy inducers (colchicine, diethylstilboestrol, griseofulvin and thiabendazole), as well as non-genotoxic compounds (mannitol and clofibrate), were tested. Four cell types were used, i.e. human lymphocytes in the presence of cytochalasin B and CHO, CHL and L5178Y cell lines, in the presence or absence of cytochalasin B, with various treatment-recovery schedules. Mitomycin C was used as a positive control for all cell types. Mannitol and clofibrate were consistently negative in all cell types and with all treatment-recovery conditions. Urethane, known to induce questionable clastogenicity, was not found as positive. Bleomycin and mitomycin C were found positive in all treatment-recovery conditions. The base and nucleoside analogs were less easy to detect, especially 5-fluorouracil due to the interference with cytotoxicity, while cytosine arabinoside was detected in all cell types depending on the treatment-recovery schedule. Aneugens (colchicine, diethylstilboestrol and griseofulvin) were all detected in all cell types. In this study, the optimal detection was ensured when a short treatment followed by a long recovery was associated with a long continuous treatment without recovery. There was no impact of the presence or absence of cytochalasin B on the detection of micronucleated cells on cell lines. Scoring micronucleated cells in both mononucleated and binucleated cells when using cytochalasin B was confirmed to be useful for the detection and the identification of aneugens. In conclusion, these results, together with previously published validation studies, provide a useful contribution to the optimisation of a study protocol for the detection of both clastogens and aneugens in the in vitro micronucleus test.

Genotoxicity test system based on p53R2 gene expression in human cells: examination with 80 chemicals

p53R2, which encodes a subunit of ribonucleotide reductase, is activated by DNA damage induced by gamma-ray and ultraviolet irradiation, and also by genotoxic chemicals such as adriamycin. For the purpose of constructing an easy-operating genotoxicity test system using human cell lines, we developed a p53R2-dependent luciferase reporter gene assay, and demonstrated dose-dependent luminescence caused by adriamycin in two human cell lines that express wild-type p53, MCF-7 and HepG2. The performance of this assay system was evaluated with 80 chemicals including those known in the Ames test as genotoxic or non-genotoxic. When the luciferase activity of cells treated with the test sample was over 200% to that of control cells in a dose-dependent increasing manner, the sample was judged positive as a genotoxic chemical. Forty of 43 Ames-positive chemicals induced luciferase activity in this assay system. Eight Ames-negative chemicals also induced luciferase activity. These eight chemicals are genotoxic in other in vitro test systems using mammalian cells. It is suggested that this assay system can be applied to rapid screening of chemicals for potential human genotoxicity.