CHARACTERISTIC CHANGES IN THE COPY NUMBER OF INTERSPERSED REPEATS IN BONE MARROW CELLS OF MICE TREATED WITH CYCLOPHOSPHAMIDE AND EXOGENOUS HUMAN DNA

Abstract

Mice were observed to get sick and die upon administration of exogenous DNA in a specific period of time following their pretreatment with the cytostatic cyclophosphamide (CP) (Dolgova et al., 2011). It was established that exogenous DNA reaches internal compartments of bone marrow cells (BMCs) where it is processed (Dolgova et al., 2012a). Thus, BMCs appear to be the primary targets for the synergic action of these preparations (Dolgova et al., 2012b).In the present study, we show that the copy number for mouse interspersed genomic repeats decreases in the genome of mouse mononuclear cells as a result of interstrand cross-link (ICL) repair after pre-treatment with cytostatic CP. This phenomenon occurs within the time span from 18 to 24 h following CP injection, which corresponds to the final step in the repair of the majority of double-strand breaks (DSBs), as predominant intermediates in ICL repair. Injections of exogenous DNA in CP-pretreated mice preserve the copy number of interspersed repeats at the original level. Our results suggest that the fragments of exogenous DNA participate in ICL-induced DSB repair, thereby compromising the repair process.

Keywords

• cyclophosphamide
• exogenous dna
• interstrand cross-links
• short interspersed repeat (sine)
• homologous recombination