ΔNp63α silences a microRNA program to aberrantly initiate a wound healing program that promotes TGFβ-induced metastasis

• Published in: Cancer research (Chicago, Ill.) Vol. 76; no. 11; pp. 3236 - 3251
• Main Authors: Calleja, Lidia Rodriguez, Jacques, Camille, Lamoureux, François, Baud'huin, Marc, Gabriel, Marta Tellez, Quillard, Thibault, Sahay, Debashish, Perrot, Pierre, Amiaud, Jerome, Charrier, Celine, Brion, Regis, Lecanda, Fernando, Verrecchia, Franck, Heymann, Dominique, Ellisen, Leif W., Ory, Benjamin
• Format: Journal Article
• Language: English
• Published: 17.03.2016
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/0008-5472.CAN-15-2317

Primary cancer cell dissemination is a key event during the metastatic cascade, but context-specific determinants of this process remain largely undefined. Multiple reports have suggested that the p53 (TP53) family member p63 (TP63) plays an anti-metastatic role through its minor epithelial isoform containing the N-terminal transactivation domain (TAp63). However, the role and contribution of the major p63 isoform lacking this domain, ΔNp63α, remain largely undefined. Here, we report a distinct and TAp63-independent mechanism by which ΔNp63α-expressing cells within a TGFβ-rich microenvironment become positively selected for metastatic dissemination. Orthotopic transplantation of ΔNp63α-expressing human osteosarcoma cells into athymic mice resulted in larger and more frequent lung metastases than transplantation of control cells. Mechanistic investigations revealed that ΔNp63α repressed miR-527 and miR-665, leading to the upregulation of two TGFβ effectors, SMAD4 and TβRII (TGFBR2). Furthermore, we provide evidence that this mechanism reflects a fundamental role for ΔNp63α in the normal wound healing response. We show that ΔNp63α-mediated repression of miR-527/665 controls a TGFβ-dependent signaling node that switches off anti-migratory miR-198 by suppressing the expression of the regulatory factor, KSRP (KHSRP). Collectively, these findings reveal that a novel microRNA network involved in the regulation of physiological wound healing responses is hijacked and suppressed by tumor cells to promote metastatic dissemination.