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The regulation of BNP transcription and DNA methylation modification in anticancer drug-induced cardiomyocyte toxicity.

Background) Genomic DNA, which contains all of the genetic information, is damaged by a variety of endogenous and environmental factors such as genotoxic chemicals, ionizing radiation and UV light. Consequently, the DNA repair process is constantly active as it responds to damage in the DNA structure. Not only cardiotoxicity of anticancer drug treatment but also ischemic heart disease and heart failure associated with overloaded pressure interfere with DNA damage response and DNA repair regulation in cardiomyocytes. We have reported that anticancer drug treatment causes a transient decrease in plasma brain natriuretic peptide (BNP) levels, but the mechanism of this decrease is unknown. In the present study, to clarify this molecular mechanism, we analyzed mouse hearts treated with anticancer drugs. Methods) C57BL/6 mice were treated with cisplatin (16 mg/kg, ip), and then BNP gene expression and DNA methylation in the heart were examined. Results) In cisplatin-treated mice, there was a transient decrease in BNP gene expression and an increase in DNA methylation of the BNP promoter region. Furthermore, DNA methyltransferase type 1 (DNMT1) was found to affect this DNA methylation. Conclusions) In cisplatin-treated mice, cardiac BNP transcription was repressed by DNA methylation. DNMT1 was suggested to be involved in this DNA methylation modification.