DNA intercalating drugs: Mechanisms of action in cancer treatment

DNA-intercalating drugs (e.g., doxorubicin) have been used in cancer treatment since the 1960s. Multiple mechanisms have been observed with these drugs. These drugs intercalate into nucleosome-free regions of chromatin, which play a crucial role in regulating gene expression and genome organization. DNA intercalation by these drugs results in a plethora of events, including DNA damage, chromatin damage (histone eviction), erosion of chromatin organization, nucleolar condensation, RNA polymerase I and/or RNA polymerase II degradation, transcription arrest, deubiquitination of histone H2B ubiquitinated at lysine 120, topoisomerase I and/or II inhibition and/or trapping, and disruption of proteins associated with the elongating RNA polymerase II. These events may occur within hours following the addition of these drugs. At later times, changes to the DNA structure (e.g., the formation of Z DNA) occur, and eventually, the cells will die via apoptosis. This review will examine the mechanisms of action of DNA-intercalating drugs, specifically two anthracyclines (doxorubicin and aclarubicin) and a heteroaromatic compound (BMH-21). Doxorubicin and aclarubicin are used clinically to treat cancer, while BMH-21 remains in preclinical development. Reports on plasma pharmacokinetics of these anthracyclines will be tabulated, and the clinical relevance of the observed mechanisms of action for doxorubicin and aclarubicin will be assessed based on this information.