Primary research

Qualitative and quantitative characteristics of the extracellular DNA delivered to the nucleus of a living cell

Vladimir A Rogachev¹ , Anastasia Likhacheva³ , Oksana Vratskikh³ , Lyudmila V Mechetina¹ , Tamara E Sebeleva¹ , Sergei S Bogachev^1,2,4 , Leonid A Yakubov² and Mikhail A Shurdov^2,4

¹  Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, prosp. Koptyuga 2, Novosibirsk, 630090, Russia

²  Panagenic International Inc. 2935 Byberry Road, Hatboro, PA, 19040, USA

³  Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia

⁴  OOO Panagen, ul. Choros-Gurkina 29, Gorno-Altaisk, 649000, Russia

author email corresponding author email

Cancer Cell International 2006, 6:23doi:10.1186/1475-2867-6-23

Published:	11 October 2006

Abstract

Background

The blood plasma and other intertissue fluids usually contain a certain amount of DNA, getting there due to a natural cell death in the organism. Cells of this organism can capture the extracellular DNA, whereupon it is delivered to various cell compartments. It is hypothesized that the extracellular DNA is involved in the transfer of genetic information and its fixation in the genome of recipient cell.

Results

The existence of an active flow of extracellular DNA into the cell is demonstrated using human breast adenocarcinoma (MCF-7) cells as a recipient culture. The qualitative state of the DNA fragments delivered to the main cell compartments (cytoplasm and interchromosomal fraction) was assessed. The extracellular DNA delivered to the cell is characterized quantitatively.

Conclusion

It is demonstrated that the extracellular DNA fragments in several minutes reach the nuclear space, where they are processed so that their linear size increases from about 500 bp to 10,000 bp. The amount of free extracellular DNA fragments simultaneously present in the nuclear space may reach up to 2% of the haploid genome. Using individual DNA fragments with a known molecular weight and sequence as an extracellular DNA, it is found that these fragments degrade instantly in the culture liquid in the absence of a competitor DNA and are delivered into the cell as degradants. When adding a sufficient amount of competitor DNA, the initial undegraded molecules of the DNA fragments with the known molecular weight and sequence are detectable both in the cytoplasm and nuclear space only at the zero point of experiments. The labeled precursor α-dNTP*, added to culture medium, was undetectable inside the cell in all the experiments.