351. PDCD4 is a CSL associated protein with a transcription repressive function in cancer associated fibroblast activation.
- Author
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Jo SH, Kim DE, Clocchiatti A, and Dotto GP
- Subjects
- Animals, Apoptosis Regulatory Proteins genetics, Cancer-Associated Fibroblasts metabolism, Carcinoma, Squamous Cell genetics, Cell Line, Tumor, Cellular Senescence, Down-Regulation, HEK293 Cells, HeLa Cells, Humans, Keratosis, Actinic genetics, Mice, Mice, SCID, Protein Binding, RNA, Small Interfering genetics, RNA-Binding Proteins genetics, Signal Transduction, Skin Neoplasms genetics, Transcription, Genetic, Xenograft Model Antitumor Assays, Apoptosis Regulatory Proteins metabolism, Cancer-Associated Fibroblasts immunology, Carcinoma, Squamous Cell metabolism, Immunoglobulin J Recombination Signal Sequence-Binding Protein metabolism, Keratosis, Actinic metabolism, RNA-Binding Proteins metabolism, Skin Neoplasms metabolism
- Abstract
The Notch/CSL pathway plays an important role in skin homeostasis and carcinogenesis. CSL, the key effector of canonical Notch signaling endowed with an intrinsic transcription repressive function, suppresses stromal fibroblast senescence and Cancer Associated Fibroblast (CAF) activation through direct down-modulation of key effector genes. Interacting proteins that participate with CSL in this context are as yet to be identified. We report here that Programmed Cell Death 4 (PDCD4), a nuclear/cytoplasmic shuttling protein with multiple functions, associates with CSL and plays a similar role in suppressing dermal fibroblast senescence and CAF activation. Like CSL, PDCD4 is down-regulated in stromal fibroblasts of premalignant skin actinic keratosis (AKs) lesions and squamous cell carcinoma (SCC). While devoid of intrinsic DNA binding capability, PDCD4 is present at CSL binding sites of CAF marker genes as well as canonical Notch/CSL targets and suppresses expression of these genes in a fibroblast-specific manner. Thus, we propose that PDCD4 is part of the CSL repressive complex involved in negative control of stromal fibroblasts conversion into CAFs.
- Published
- 2016
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