Investigation of hycanthone binding to DNA in chromatin with different supra-organization, composition, and function

Hycanthone is a drug used for the clinical treatment of schistosomiasis, although inducing chromosomes breaks and mutagenesis when it enters the DNA double helix. Based on visual observation of characteristics of basophilia and anisotropy after toluidine blue staining, a preferential binding of hycanthone to heterochromatin could be demonstrated for the nuclei of the Malpighian tubules of Triatoma infestans. In other cellular systems like cattle kidney cells in culture, plant cells, and mouse lymphocytes, the drug could be demonstrated to bind heterochromatin and euchromatin, irrespective of the packing state of the latter. When penetrating the various heterochromatin types (with the exception of T. infestans), the drug induced a chromatin loosening that could favor incidence of chromatin breaks. The variation of hycanthone binding to DNA in different cell types is possibly related to differences in composition, stereo-arrangement and stability of the DNA-protein complexes involved.