CpG methylation potentiates pixantrone and doxorubicin-induced DNA damage and is a marker of drug sensitivity

Abstract

DNA methylation is an epigenetic modification of the mammalian genome that occurs predominantly at cytosine residues of the CpG dinucleotide. Following formaldehyde activation, pixantrone alkylates DNA and particularly favours the CpG motif. Aberrations in CpG methylation patterns are a feature of most cancer types, a characteristic that may determine their susceptibility to specific drug treatments. Given their common target, DNA methylation may modulate the DNA damage induced by formaldehyde-activated pixantrone. In vitro transcription, mass spectrometry and oligonucleotide band shift assays were utilized to establish that pixantrone–DNA adduct formation was consistently enhanced 2–5-fold at discrete methylated CpG doublets. The methylation-mediated enhancement was exquisitely sensitive to the position of the methyl substituent since methylation at neighboring cytosine residues failed to confer an increase in pixantrone–DNA alkylation. Covalent modification of DNA by formaldehyde-activated doxorubicin, but not cisplatin, was augmented by neighbouring CpG methylation, indicating that modulation of binding by CpG methylation is not a general feature of all alkylators. HCT116 colon cancer cells vastly deficient in CpG methylation were 12- and 10-fold more resistant to pixantrone and doxorubicin relative to the wild-type line, suggesting that these drugs may selectively recognize the aberrant CpG methylation profiles characteristic of most tumour types.

Influence OF anticancer drugs on DNA methylation in liver of female mice

“…DNA methylation level from CpG islands linked to twenty eight genes whose expression levels had been shown to contribute with the resistance against DNA double strand break induced drugs. These data were supported in some way to our data in documenting DNA methylation by different doses of doxorubicin drug in non-tumor female mice [28] assessed the CpG methylation aberrations induced by pixantrone and doxorubicin. A characteristic that may determine the most cancer types to specific drug treatments and is a marker of drug sensitivity.…”

The Novel Anthracenedione, Pixantrone, Lacks Redox Activity and Inhibits Doxorubicinol Formation in Human Myocardium: Insight to Explain the Cardiac Safety of Pixantrone in Doxorubicin-Treated Patients

“…Moreover, it is known that, in cancer cells, the mode of action of PIX was not confined to inhibiting topoisomerase II, but extended to forming PIX-formaldehyde conjugates that crosslinked to DNA much more efficaciously than equivalent DOX conjugates (Evison et al, 2009;Cell Therapeutics Inc., 2012). This anticipates that, in cancer cells altered by prior waves of DOX clearance, a limited uptake of PIX would be outweighed by its greater potency in damaging DNA.…”

Pixantrone dimaleate for treating non-Hodgkin’s lymphoma

“…More precisely, it has been shown that pixantrone intercalates from the DNA major groove [19]. However, evidence of minor groove association was also observed.…”

“…Its novel mode of action offers a reduced potential for generating reactive oxygen species, binding iron and forming alcohol metabolites that cause the cardiac toxicity of anthracycline [14,17,18]. Moreover, it has been demonstrated that CpG methylation, which is specific to tumour cells, augments the generation of covalent pixantrone--DNA adducts [19].…”