Distinct effects of topoisomerase II inhibitors on tumor cell lines (part 2)

One major class of anti-cancer drugs targets topoisomerase II to induce DNA double-strand breaks and cell death of fast growing cells. Here, we compare three members of this class - the antracyclines doxorubicin and aclarubicin, and a chemically unrelated compound, etoposide. Aclarubicin does not induce DNA breaks. We define a new activity for the antracyclines: unsupported histone eviction from ´open´ or loosely packed chromosomal areas reflecting exon and promoter regions. As a result, the epigenome and the transcriptome are strongly affected. Tissue culture cells were treated with doxorubicin, aclarubicin or etoposide for 2 hours. Then drugs were removed by extensive washing. cells were further cultured for indicated days before total RNA were extracted and compared to un-treated control.