Arginine methylation is an epigenetic modification that receives increasing interest as it plays an important role in several diseases. This is especially true for hormone-dependent cancer, seeing that histone methylation by arginine methyltransferase I (PRMT1) is involved in the activation of sexual hormone receptors. Therefore, PRMT inhibitors are potential drugs and interesting tools for cell biology. A dapsone derivative called allantodapsone previously identified by our group served as a lead structure for inhibitor synthesis. Acylated derivatives of p-aminobenzenesulfonamides and the antilepra drug dapsone were identified as new inhibitors of PRMT1 by in vitro testing. The bis-chloroacetyl amide of dapsone selectively inhibited human PRMT1 in the low micromolar region and was selective for PRMT1 as compared to the arginine methyltransferase CARM1 and the lysine methyltransferase Set7/9. It showed anticancer activity on MCF7a and LNCaP cells and blocked androgen dependent transcription specifically in a reporter gene system. Likewise, a transcriptional block was also demonstrated in LNCaP cells using quantitative RT-PCR on the mRNA of androgen dependent genes.
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