THE POLYCOMB PROTEINS RING1B AND EZH2 REPRESS THE TUMORAL PROINFLAMMATORY FUNCTION IN METASTASIZING PRIMARY CUTANEOUS SQUAMOUS CELL CARCINOMA

Cutaneous squamous cell carcinoma (cSCC) is the second most common malignancy in humans and approximately 5% metastasize, usually to regional lymph nodes. Epigenetic regulation of gene expression may allow tumoral cells to acquire new functions in order to escape from the primary tumor. The aim of this study was to investigate the expression and function of proteins of the Polycomb family of epigenetic regulators in the metastatic process of cSCC. A higher expression of RING1B and EZH2 was detected by immunohistochemistry in a series of primary cSCC tumors that metastasized (MSCC) when compared to non metastasizing cSCC (non MSCC). Stable downregulation of RING1B and EZH2 in cSCC cells results in enhanced expression of inflammatory cytokines and activation of the NFB signaling pathway. Accordingly, non MSCC display higher levels of membranous pS176 IKK and their stroma is enriched in neutrophils and eosinophils when compared to MSCC. In vitro, hematopoietic cells exhibit a substantial migratory response to supernatants from Polycomb depleted cSCC cells. Altogether these data indicate that RING1B and EZH2 repress the innate inflammatory cSCC function and impair tumor immunosurveillance and suggest that patients with high risk cSCC could benefit from clinical therapies addressed to harness the immune response.

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Hernández-Ruiz E, Toll A, García-Diez I, Andrades E, Ferrandiz-Pulido C, Masferrer E, Yébenes M, Jaka A, Gimeno J, Gimeno R, García-Patos V, Pujol RM, Hernández-Muñoz I