Reciprocal epigenetic remodeling mediated by polycomb and DNMT3B control testicular cancer hypersensitivity and resistance to 5-aza and cisplatin

We undertook a pharmacogenomic approach in order to better understand mechanisms of hypomethylating agent hypersensitivity of TGCTs by generating a panel of acquired 5-aza resistant TGCT cells and contrasting these to previously generated acquired cisplatin resistance cells from the same parent. Interestingly, there was a reciprocal relationship between cisplatin and 5-aza sensitivity, with cisplatin resistance associated with increased sensitivity to 5-aza and 5-aza resistance associated with increased sensitivity to cisplatin. Unbiased transcriptome analysis revealed 5-aza resistant cells strongly downregulated polycomb target gene expression, the exact opposite of the finding for cisplatin resistant cells which upregulated polycomb target genes. This was associate with a dramatic increase in H3K27me3 and substantial decrease in DNMT3B levels in 5-aza resistant cells, the exact opposite changes seen in cisplatin resistant cells. Overall design: gene expression of parental and Aza resistant cell lines in biological triplicate were analysed