Mechanisms leading to the expression of recessive alleles: the use of polymorphic microsatellites and whole-chromosome painting probes to analyze mouse tumors, mutants, and micronuclei

Characterization of the genotoxicity of anthraquinones in mammalian cells

Naturally occurring 1,8-dihydroxyanthraquinones are under consideration as possible carcinogens. Here we wanted to elucidate a possible mechanism of their genotoxicity. All three tested anthraquinones, emodin, aloe-emodin, and danthron, showed capabilities to inhibit the non-covalent binding of bisbenzimide Hoechst 33342 to isolated DNA and in mouse lymphoma L5178Y cells comparable to the topoisomerase II inhibitor and intercalator m-amsacrine. In a cell-free decatenation assay, emodin exerted a stronger, danthron a similar and aloe-emodin a weaker inhibition of topoisomerase II activity than m-amsacrine. Analysis of the chromosomal extent of DNA damage induced by these anthraquinones was performed in mouse lymphoma L5178Y cells. Anthraquinone-induced mutant cell clones showed similar chromosomal lesions when compared to the topoisomerase II inhibitors etoposide and m-amsacrine, but were different from mutants induced by the DNA alkylator ethyl methanesulfonate. These data support the idea that inhibition of the catalytic activity of topoisomerase II contributes to anthraquinone-induced genotoxicity and mutagenicity.

Early cancer detection by microsatellite marker analysis

A major goal of tumor biology has been the development of tumor markers that are useful for the diagnosis and management of cancer. A drawback associated with many of these markers is that they are not unique to tumor cells, but rather are normal or developmental antigens which are overexpressed in tumor tissue Therefore, determination of possible malignancy is based on a designated expression level rather than a clear-cut difference. Studies have shown that DNA from tumor cells has a pattern of chromosomal deletion clearly distinguishable from normal cell DNA, and more importantly, DNA from tumor cells can be detected in the serum of cancer patients. Particular chromosomal deletion patterns are associated with specific tumor types. It is hypothesized that individuals at risk for certain genetically well-characterized cancers, could be successfully screened for those cancers by a PCR-based blood test. In this way, neoplasia could be detected at earlier, more treatable stages of development.