CSL ChIP-Seq on human keratinocytes

Down-modulation or loss-of-function mutations of the Notch 1 and 2 genes are associated with development of squamous cell carcinoma (SCC), a very frequent and therapy-resilient malignancy in skin, head/neck (H/N), lung and other surface epithelia. In this context, surprisingly little is known on the role of CSL (RBP-Jk), key effector of canonical Notch signaling endowed with intrinsic transcription repressive function. CSL expression is decreased in upper epidermal layers and differentiating primary human keratinocytes (HKCs), while it is up-regulated in premalignant and malignant SCC lesions and SCC cell lines from skin, Head/Neck and lung. Increased CSL levels enhance proliferation and self-renewal potential of HKCs and SCC cells, while its silencing induces growth arrest and apoptosis. In vivo, SCC cells with increased CSL levels give rise to rapidly expanding tumors, while upon CSL silencing they form smaller and more differentiated tumors with enhanced inflammatory infiltrate. Global transcriptomic analysis of HKC and SCC cells plus/minus CSL silencing reveals major modulation of apoptotic, cell cycle and pro-inflammatory genes, with no significant association with Notch or keratinocyte differentiation gene signatures. KDM6B, a histone demethylase gene with highly context dependent functions, is a direct CSL negative target, with an inverse role of CSL in HKC and SCC self-renewal and tumorigenesis, with IL6 as a target of likely significance. CSL / KDM6B protein expression could be used as biomarkers of SCC development and novel indicators of cancer treatment. Overall design: CSL ChIP-Seq on HKCs (human keratinocytes)