Effects of 5-aza-2'-deoxycytidine on DNA Methylation within Female Mouse Reproductive Tissues

Abstract

Abstract 5-aza-2'-deoxycytidine (decitabine), is a chemotherapeutic DNA methyltransferase (DNMT) inhibitor widely used to treat myelodysplastic syndrome and acute myeloid leukemias. Decitabine’s anti-neoplastic activity is thought to result from inhibition of DNMTs leading to passive demethylation of 5’methylcytosines (5mC) in rapidly dividing tissues, resulting in cell death. However, we previously reported paradoxical effects on DNA methylation by decitabine in somatic tissues. Given the potential for lasting damage to DNA methylation in reproductive tissues from even short courses of decitabine in reproductive age humans, we chose to characterize its long-term effects here. Mice were treated with two clinically relevant doses of decitabine (0.15 mg/kg, 0.35 mg/kg) for 7 weeks and DNA methylation was assessed within female reproductive tract tissues. We found methylated cytosines within the ovary to be the least sensitive to decitabine exposure at both doses, whereas the uterus and the oviduct exhibited higher 5mC dysregulation, surprisingly biased towards hypermethylation at the 0.35 mg/kg dose. We identified the sites of differential methylation; revealing specific genes and pathways involved in cell differentiation, development, communication, and cell signaling that were universally altered in all tissues. In addition to our differential methylation data, we identified dysregulated transcription and pathways using RNAseq analyses. Overall, our findings show decitabine exposure causes an epigenetic insult to DNA methylation within female reproductive tissues. Our data provides evidence that further evaluation is needed to fully establish the long-term phenotypic effects post-decitabine exposure.