EZH2-inhibitor DZNep enhances apoptosis of renal tubular epithelial cells in presence and absence of cisplatin.

Background: The enhancer of zeste homolog 2 (EZH2) is a histone methyltransferase and induces the trimethylation of histone H3 lysine 27 (H3K27me3) in the promoter of many key genes; EZH2 acts as a transcriptional repressor and is an epigenetic regulator for several cancers. However, the role of EZH2 in nonneoplastic diseases, such as kidney diseases, is unknown and has been investigated.

Materials and method: NRK-52E cells were treated with DZNep, a potent inhibitor of EZH2, with different concentrations and for different times to evaluate the apoptosis level of NRK-52E cells by Western blot and Flow cytometry analysis. The binding of EZH2 to the Deptor promoter was determined by ChIP assay.

Results: The inhibition of EZH2 with 3-deazaneplanocin A (DZNep), a specific inhibitor of EZH2, led to the apoptosis of NRK-52E cells and the inhibition of mTORC1 and mTORC2 activity. A ChIP assay demonstrated that EZH2 bound the promoter region of Deptor, an endogenous inhibitor of mTORC1 and mTORC2, and regulated the transcription of Deptor by modulating H3K27me3 in its promoter region. Further experiments were performed to examine the effects of EZH2 inhibition on cisplatin-induced injured cells. Cisplatin induced the activation of mTORC1 and mTORC2 and apoptosis in NRK-52E cells, and DZNep inhibited mTORC1 and mTORC2 activity and aggravated cell apoptosis.

Conclusions: These data suggested that EZH2 inhibition increased the transcription of Deptor by modifying H3K27me3 in its promoter region, subsequently inhibited mTORC1 and mTORC2 activities, downregulated the expression of apoptosis suppressor genes, and finally led to apoptosis in renal tubular cells. The inhibition of EZH2 aggravated the cisplatin-induced injury in renal tubular cells by inactivating the mTOR complexes. The present study provides new insight into renal protection and suggests that EZH2 might be a target.