Intercalation and Induction of Strand Breaks by Adriamycin and Daunomycin: A Study with Human Genomic DNA

Abstract

The anticancer drugs Adriamycin (ADR) and Daunomycin (DNM) of the anthracycline family are effective in treating a variety of cancers. Although their interactions with other cellular targets may play a role in the selective cytotoxicity of these drugs, it is generally believed that intercalation with DNA is essential for their activity. However, a relationship has not yet been established between intercalation and cellular processes leading to cytotoxicity. The present study was designed to investigate the relationship, if any, between intercalation and DNA strand breaks. ADR and DNM were observed to be strong intercalators of human genomic DNA by absorption and fluorimetric methods that were further substantiated by rise in thermal melting temperature. DNM is the better intercalator of the two, which is also evident from circular dichroic spectral changes. DNA strand breaks, considered to be an index of genotoxicity, was assayed by single cell gel electrophoresis (SCGE; comet assay). ADR and DNM induced equivalent genotoxicity in normal human lymphocytes at a clinically used dose, which was observed to be independent of intercalation efficiency though positively correlated to yield of reactive oxygen species.

Biophysical studies of mutated K562 DNA (erythroleukemic cells) binding to adriamycin and daunomycin reveal that mutations induce structural changes influencing binding behavior

“…Binding to normal genomic DNA is reported (Ghosh et al, 2012) to remarkably quench the fluorescence of these drugs. Similar binding to mutated DNA isolated from K562 cells also resulted in quenching of the fluorescence of these drugs, eventually leading to saturation (figure not shown).…”

“…Previous binding studies of ADR and DNM with normal human genomic DNA isolated from peripheral blood showed preferred binding with DNM over ADR. These drugs also showed higher genotoxicity to normal lymphocytes (Ghosh et al, 2012).…”

“…Isolated DNA was further purified by phenol chloroform method and lyophilized (Ghosh et al, 2012). Lyophilized DNA was dissolved in 50 mM phosphate buffer (pH 6.5) when required and the purity was ascertained by the ratio of A 260 /A 280 ; samples with the ratio between 1.8 and 2.0 were considered pure.…”

“…DNM is more effective than ADR against acute myeloid leukemia (AML), which is often attributed to their structural differences (Cutts et al, 2007). According to our earlier studies, other than structural differences, sequence specificity and the yield of reactive oxygen species (ROS) also determine the efficacy of these drugs in normal lymphocytes (Ghosh, Hossain, Saha, Dey, & Suresh Kumar, 2012). In continuation, the consequences of mutations on drug binding behavior of K562 genome compared to normal human genome are presently our area of interest and investigation.…”

The peroxidase activity of ADM-Fe3+ cooperates with lipid peroxidation: The participation of hydroperoxide and hydroxyl radicals in the damage to proteins and DNA

“…The cytotoxic action of ADM has been explained by its intercalation into DNA [4], which results in inhibition of replication, transcription, and ultimately, translation. The free radicals generated by ADM participate in causing the DNA damage, lipid peroxidation and mitochondrial dysfunctions [5][6][7][8].…”