An FGFR 3/ MYC positive feedback loop provides new opportunities for targeted therapies in bladder cancers

• DOI: 10.15252/emmm.201708163
• Publication Date: 2018-02-21T01:10:32Z
• Authors: Mélanie Mahe; Florent Dufour; Hélène Neyret‐Kahn; Aura Moreno‐Vega; Claire Beraud; Mingjun Shi; Imene Hamaidi; Virginia Sanchez‐...; Clementine Krucker; Marion Dorland‐Ga...; Elodie Chapeaublanc; Remy Nicolle; Hervé Lang; Celio Pouponnot; Thierry Massfelder; François Radvanyi; Isabelle Bernard‐...
• Keywords: 0301 basic medicine; Medicine (General); Cell Survival; Urogenital System; [SDV.CAN]Life Sciences [q-bio]/Cancer; p38; MYC; QH426-470; [SDV.MHEP.UN]Life Sciences [q-bio]/Human health and pathology/Urology and Nephrology; p38 Mitogen-Activated Protein Kinases; 03 medical and health sciences; R5-920; [SDV.BBM.GTP]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Genomics [q-bio.GN]; Cell Line, Tumor; Genetics; Humans; Receptor, Fibroblast Growth Factor, Type 3; p38 Subject Categories Cancer; BET inhibitors; Research Articles; Cell Proliferation; Azepines; Triazoles; 3. Good health; Urinary Bladder Neoplasms; FGFR3; bladder cancer; Signal Transduction

FGFR3 alterations (mutations or translocation) are among the most frequent genetic events in bladder carcinoma. They lead to an aberrant activation of FGFR3 signaling, conferring an oncogenic dependence, which we studied here. We discovered a positive feedback loop, in which the activation of p38 and AKT downstream from the altered FGFR3 upregulates MYC mRNA levels and stabilizes MYC protein, respectively, leading to the accumulation of MYC, which directly upregulates FGFR3 expression by binding to active enhancers upstream from FGFR3 Disruption of this FGFR3/MYC loop in bladder cancer cell lines by treatment with FGFR3, p38, AKT, or BET bromodomain inhibitors (JQ1) preventing MYC transcription decreased cell viability in vitro and tumor growth in vivo A relevance of this loop to human bladder tumors was supported by the positive correlation between FGFR3 and MYC levels in tumors bearing FGFR3 mutations, and the decrease in FGFR3 and MYC levels following anti-FGFR treatment in a PDX model bearing an FGFR3 mutation. These findings open up new possibilities for the treatment of bladder tumors displaying aberrant FGFR3 activation.