PPARγ is a tumor suppressor in basal bladder tumors offering new potential therapeutic opportunities
Résumé
PPARactivation is a critical event in luminal muscle-invasive bladder cancer (MIBC) tumorigenesis, favoring both tumor cell growth and microenvironment modulation toward tumor immune escape. Conversely, the down-regulation of PPARactivity in basal MIBC suggests tumor suppressive effects in this subgroup. Here, we report genetic, epigenetic and functional evidence to support the tumor suppressor role for PPAR in basal bladder tumors. We identified hemizygous deletions, DNA hyper-methylation and loss-of-function mutations of PPARin basal MIBC, associated with PPAR under-expression and its decreased activity. Re-expression of PPARin basal tumor cells resulted in the activation of PPAR-dependent transcription program that modulated fatty acid metabolism and cell differentiation and decreased cell growth, which could partly rely on EGFR down-regulation. Structure-function studies of two PPAR mutant revealed a destabilization of a region important for coactivator recruitment and should help develop potent molecules to activate PPAR as a therapeutic strategy for basal MIBC. The identification of this subtype-dependent dual role of PPAR in MIBC strengthens the critical role of PPAR in bladder tumorigenesis and reinforces the interest in stratified medicine based on tumor molecular subtyping.
Domaines
Sciences du Vivant [q-bio]Origine | Fichiers produits par l'(les) auteur(s) |
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