Loss of KDM6A characterizes a poor prognostic subtype of human pancreatic cancer and potentiates HDAC inhibitor lethality

Abstract

Although genomic analysis have recently discovered the malignant subtype of human pancreatic ductal adenocarcinoma (PDAC) characterized by frequent mutations of histone demethylase KDM6A, the biological and molecular roles still remain obscure. We herein elucidated the clinical and biological impacts of KDM6A deficiency on human PDAC and identified the therapeutic potential by pathological and molecular evaluation. Immunohistochemical analysis suggested that loss of KDM6A in cancerous tissues was an independent prognostic factor for both recurrence-free and overall survival in the 103 tumor specimens surgically resected from patients with PDAC. We established KDM6A knocked out cells by using the CRISPR/Cas9 system and KDM6A-expressed cells by doxycycline-inducible system from each two human PDAC cell lines, respectively. KDM6A knockout enhanced aggressive traits of human PDAC cell lines, whereas KDM6A overexpression suppressed them. Microarray analysis revealed reduced expression of 22 genes including five well-known tumor suppressors, such as CDKN1A, and ChIP-PCR analysis displayed depleted enrichment of histone H3 lysine 27 acetylation (H3K27ac) at the promoter regions of the five candidates. The epigenetic alterations were induced by the impaired recruitment of histone acetyltransferase p300, which cooperatively interacted with KDM6A. Consistent with these results, the KDM6A knockout cells demonstrated higher vulnerability to histone deacetylase (HDAC) inhibitors through the reactivation of CDKN1A in vitro and in vivo than the KDM6A wild-type. In conclusion, KDM6A exhibited essential roles in human PDAC as a tumor suppressor and KDM6A deficiency could be a promising biomarker for unfavorable outcome in PDAC patients and a potential surrogate marker for response to HDAC inhibitors.