SMALL POLYDISPERSED CIRCULAR DNA (SPCDNA) IN HUMAN-CELLS - ASSOCIATION WITH GENOMIC INSTABILITY

Small Polydispersed Circular DNA (spcDNA) was suggested to be associat ed with genetically unstable cells. However, until now, qualitative an d quantitative research has been limited due to the lack of efficient methods for detection and analysis. We developed a two-dimensional (2- D) neutral-neutral gel electrophoresis assay for the identification, c haracterisation and quantitation of spcDNA. Using this method, we esta blished the relation of spcDNA to genetic and induced genomic instabil ity in human cells, both in vitro and in vivo. Enhanced amounts of spc DNA were found in genetically unstable cells and tissues. spcDNA was d etected in a tumor cell-line (HeLa) and in tumor tissue (colon carcino ma) as well as in fibroblasts derived from patients suffering from the genomic instability disease, Fanconi's Anemia. We failed to detect sp cDNA in the genetically stable normal human fibroblasts. However, foll owing treatment with the initiating carcinogen MNNG, an induction of s pcDNA was observed. The level of spcDNA was quantified according to mi tochondrial DNA (mtDNA) standards. In light of these findings, we disc uss the possible role of spcDNA as a marker and an enhancer of genomic instability.