Notch-effector CSL promotes squamous cell carcinoma by repressing histone demethylase KDM6B
Dania Al Labban, … , Renato Panizzon, G. Paolo Dotto
Dania Al Labban, … , Renato Panizzon, G. Paolo Dotto
Published June 1, 2018; First published May 14, 2018
Citation Information: J Clin Invest. 2018;128(6):2581-2599. https://doi.org/10.1172/JCI96915.
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Research Article Cell biology Oncology

Notch-effector CSL promotes squamous cell carcinoma by repressing histone demethylase KDM6B

Abstract

Notch 1/2 genes play tumor-suppressing functions in squamous cell carcinoma (SCC), a very common malignancy in skin and internal organs. In contrast with Notch, we show that the transcription factor CSL (also known as RBP-Jκ), a key effector of canonical Notch signaling endowed with intrinsic transcription-repressive functions, plays a tumor-promoting function in SCC development. Expression of this gene decreased in upper epidermal layers and human keratinocytes (HKCs) undergoing differentiation, while it increased in premalignant and malignant SCC lesions from skin, head/neck, and lung. Increased CSL levels enhanced the proliferative potential of HKCs and SCC cells, while silencing of CSL induced growth arrest and apoptosis. In vivo, SCC cells with increased CSL levels gave rise to rapidly expanding tumors, while cells with silenced CSL formed smaller and more differentiated tumors with enhanced inflammatory infiltrate. Global transcriptomic analysis of HKCs and SCC cells with silenced CSL revealed major modulation of apoptotic, cell-cycle, and proinflammatory genes. We also show that the histone demethylase KDM6B is a direct CSL-negative target, with inverse roles of CSL in HKC and SCC proliferative capacity, tumorigenesis, and tumor-associated inflammatory reaction. CSL/KDM6B protein expression could be used as a biomarker of SCC development and indicator of cancer treatment.

Authors

Dania Al Labban, Seung-Hee Jo, Paola Ostano, Chiara Saglietti, Massimo Bongiovanni, Renato Panizzon, G. Paolo Dotto

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Figure 9

KDM6B as a direct target of CSL.

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KDM6B as a direct target of CSL. (A) Venn diagram illustrating overlap b...
(A) Venn diagram illustrating overlap between number of genes bound by CSL (ChIP-seq profile) and those upregulated by silencing of the gene (RNA-seq profile) in HKCs. (B) List of overlapping genes grouped by biological function. Highlighted are direct CSL target genes commonly upregulated by CSL gene silencing in HKCs and SCC13 cells. (C) Upper panel: graphic illustration of the position of CSL-binding peaks revealed by Chip-seq analysis for the KDM6B gene, utilizing ENCODE information for promoter and enhancer localization, as indicated by islands of histone H3 modifications (K4me3 and K27Ac) along with position of the transcription start site (TSS) (81) and coding exons (boxes). Also indicated are positions of sites tested by direct ChIP assays. Lower panel: ChIP assays for independent confirmation of Chip-seq results of CSL binding to the indicated sites within the KDM6B genomic locus. HKCs were processed for ChIP assays with anti-CSL antibodies versus nonimmune IgG controls, using tagmentation for signal amplification (see Methods). Shown are CSL fold enrichments relative to nonimmune controls (NB, nonbinding). (D) The same ChIP samples as in C were tested for CSL fold enrichment of predicted segments of the HES1 gene-promoter region as positive controls for the assay.