Evaluation of chemopreventive agents for genotoxic activity.

We conducted genetic toxicity evaluations of 11 candidate chemopreventive agents with the potential for inhibiting carcinogenesis in humans at increased risk of cancer. The compounds were evaluated for bacterial mutagenesis in the Salmonella-E. coli assay, for mammalian mutagenesis in mouse lymphoma cells, for chromosome aberrations in Chinese Hamster Ovary (CHO) cells, and for micronucleus induction in mouse bone marrow.

Gene expression profiling of mouse host response to Listeria monocytogenes infection.

The purpose of this study was to evaluate gene expression profiles in the liver and blood for prediction of infection severity from Listeria monocytogenes (LM). Mice were injected with medium broth (control) or a nonlethal or lethal dose of LM and sacrificed 6 h later. Gene expression changes were determined using Affymetrix MGU74Av2 GeneChips and confirmed by real-time polymerase chain reaction analysis.

Evaluation of mutant frequencies of chemically induced tumors and normal tissues in lambda/cII transgenic mice.

Genomic instability has been implicated as an important component in tumor progression. Evaluation of mutant frequencies (MFs) in tumors of transgenic mice containing nontranscribed marker genes should be useful for quantitating mutation rates in tumors as the physiologically inactive transgene provides neither a positive nor a negative selective pressure on the tumor. We have conducted long-term carcinogenicity studies in lambda/cII transgenic B6C3F1 mice using a variety of genotoxic and nongenotoxic test agents and have evaluated the mutant frequencies in both tumors and normal tissues from these animals.

Genotoxicity and toxicity of the potential cancer-preventive agent polyphenon E.

The potential health benefits of green tea continue to attract public and scientific interests and are attributed in part to polyphenolic catechin constituents. Polyphenon E (Poly E) is a decaffeinated green tea catechin mixture containing about 50% epigallocatechin gallate and 30% other catechins. We evaluated the toxicity and genotoxicity of Poly E by using two in vitro assays: bacterial mutagenesis in a Salmonella typhimurium-E.