Published in Cancer Detection and Prevention 1998; 22(Supplement 1).

Flavopereirine is an intercalating agent for non-supercoiled DNA

Hervé A. Calvez

Molecular International Research Ltd.

AIM : The aim of our studies was to demonstrate that flavopereirine, alcaloid from β-carboline class and containing one positively and a second negatively charged nitrogen atom, interacts with destabilized and transcriptionally active DNA from cancer cells and non-supercoiled circular plasmid DNA. METHODS: DNA from U251 BCNU resistant glioblastoma cells, G361 melanoma cells and CRL1656 MPF normal astrocytes was evaluated by electrophoresis in agarose gel with range of flavopereirine concentration from 200 to 800 microM. Topology study was based on the property of flavopereirine to preserve circular DNA from restriction enzyme which can generate linear DNA. Plasmid DNAs were separated by electrophoresis in agarose gel. pBR322 plasmid and Hind III enzyme were used with a range of flavopereirine concentration from 10 to 1000 µM. Results : Relaxed DNA from cancer cells preferentially binds flavopereirine and because of the positively charged nitrogen atom is neutralized and doesn’t run in the gel like DNA from healthy cells. Supercoiled circular DNA is protected from restriction enzyme activity whereas supercoiled circular plasmid DNA is open. CONCLUSION : Our experiments demonstrate that DNA with particular topology is used as a target by flavopereirine. It was previously shown that flavopereirine concentrates in the tumor cells nuclei and nucleoli while it does not enter normal cells. Differential behavior correlates with a difference in the secondary structure between cancer and normal cells DNAs. Flavopereirine behavior with small circular plasmid may be given as a model of interaction : it interacts with non-supercoiled circular DNA which is protected against restriction enzyme effect. Spatial structure of cancer cells DNA is very different from healthy cells DNA and might be the base for a molecular selectivity more important than only nucleotide sequence and gene expression.

KEY WORDS: flavopereirine, topology, cancer DNA, cancer DNA, pBR322, .

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Paper presented at the International Symposium on the Impact of Biotechnology on Prediction, Prevention and Treatment of Cancer; Nice, France; October 24 - 27, 1998; in the section on Anticancer Therapies.