Research ArticleCancer

HIF activation causes synthetic lethality between the VHL tumor suppressor and the EZH1 histone methyltransferase

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Science Translational Medicine  12 Jul 2017:
Vol. 9, Issue 398, eaal5272
DOI: 10.1126/scitranslmed.aal5272

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Renal cancer’s loss is patients’ gain

Clear cell renal cell carcinoma is the most common form of kidney cancer, and it is typically linked to the loss of von Hippel–Lindau protein (pVHL), a tumor suppressor. This loss results in activation of genes that are normally induced by hypoxia, including some histone demethylases. Chakraborty et al. discovered that increased H3K27 demethylase activity renders pVHL-deficient cells hyperdependent on an opposing H3K27 methyltransferase, EZH1, for survival. Inhibition of EZH1 is lethal for these cells.

Abstract

Inactivation of the von Hippel–Lindau tumor suppressor protein (pVHL) is the signature lesion in the most common form of kidney cancer, clear cell renal cell carcinoma (ccRCC). pVHL loss causes the transcriptional activation of hypoxia-inducible factor (HIF) target genes, including many genes that encode histone lysine demethylases. Moreover, chromatin regulators are frequently mutated in this disease. We found that ccRCC displays increased H3K27 acetylation and a shift toward mono- or unmethylated H3K27 caused by an HIF-dependent increase in H3K27 demethylase activity. Using a focused short hairpin RNA library, as well as CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 (CRISPR-associated protein 9) and a pharmacological inhibitor, we discovered that pVHL-defective ccRCC cells are hyperdependent on the H3K27 methyltransferase EZH1 for survival. Therefore, targeting EZH1 could be therapeutically useful in ccRCC.

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