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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Categories: 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 4

Positive role of CSL in promoting proliferative potential of skin, oral, and lung SCC cells.

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Positive role of CSL in promoting proliferative potential of skin, oral,...
(A) Cell lines derived from skin (SCC13), oral (FaDu), and lung (H520) SCCs stably infected with lentiviral vector for inducible Myc-tagged CSL versus empty vector control (pIND20) were analyzed 2 days after doxycycline treatment for CSL expression by immunoblotting. Numbers refer to relative folds of CSL expression using actin for normalization. (B) The same SCC cells as in A were plated at a limited density, and colony formation was measured. (C) The same SCC cells as in B were plated in Matrigel suspension. Number and size of spheroids were assessed using ImageJ software. (D) Cell lines derived from skin (SCC12, SCC13), oral (SCCO22, SCCO28, and FaDu), and lung (H520 and H2170) SCCs infected with 2 shRNA lentiviruses against CSL were analyzed for CSL expression by immunoblotting. (E) The same SCC cells as in D were plated at a limited density, and colony formation was measured. (F) The same SCC cells as in E were tested for cell metabolic activity assays. (G) The same SCC cells as in E were plated in Matrigel suspension. Shown are representative images of spheroids formed by FaDu cells. Scale bars: 250 μm. (B and C) Data are shown as mean ± SEM, 2-tailed unpaired t test. n = 3 independent experiments. (E–G) Data are shown as mean ± SEM. *P < 0.05; **P < 0.005; ***P < 0.0005, 1-way ANOVA with Dunnett’s test. n = 3 independent experiments.