Evidence for the genotoxic effect of daunomycin in multipotent hematopoietic cells of mouse bone marrow: Chromatin proteins analysis

Severe bone marrow suppression and anemia are the main side effects of using chemotherapeutic agents like daunomycin. In this study the effect of daunomycin on viability and chromosomal proteins of multipotent hematopoietic cells (MHCs) of mouse bone marrow was investigated. The cells were separated from mature cells according to their adherence, incubated in the absence and presence of various concentrations of daunomycin and viability was determined by trypan blue exclusion and MTT assay. The histones and high mobility group (HMG) proteins were extracted by acid and salt, respectively and analyzed on SDS-PAGE and immunoblot. The results revealed that daunomycin exhibited time and dose dependent cytotoxicity on the cells and upon increasing the concentrations of drug, the extractability of histone and HMG proteins decreased. Agarose gel electrophoresis showed aggregation of DNA in the presence of drug. Flow cytometry analysis suggested that there are differences in type and amount of histones H2A and H2B of these cells in comparison with thymus histones. Moreover histone H3 was not subjected to trimethylation at lysine 9 and daunomycin decreased H3K9 dimethylation and H3K9 acetylation in these cells in a dose-dependent manner. From these results it is concluded that the binding of daunomycin to chromatin precedes chromatin of multipotent hematopoietic cells of bone marrow into compaction/aggregation and beside DNA, histones and HMG proteins also play an important role in this process.