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Trp53 and Rb1 regulate autophagy and ligand-dependent Hedgehog signaling


Ligand-dependent activation of Hedgehog (Hh) signaling in cancer occurs without mutations in canonical pathway genes. Consequently, the genetic basis of Hh pathway activation in adult solid tumors, such as small-cell lung cancer (SCLC), is unknown. Here we show that combined inactivation of Trp53 and Rb1, a defining genetic feature of SCLC, leads to hypersensitivity to Hh ligand in vitro, and during neural tube development in vivo. This response is associated with the aberrant formation of primary cilia, an organelle essential for canonical Hh signaling through smoothened, a transmembrane protein targeted by small-molecule Hh inhibitors. We further show that loss of both Trp53 and Rb1 disables transcription of genes in the autophagic machinery necessary for the degradation of primary cilia. In turn, we also demonstrate a requirement for Kif3a, a gene essential for the formation of primary cilia, in a mouse model of SCLC induced by conditional deletion of both Trp53 and Rb1 in the adult airway. Our results provide a mechanistic framework for therapeutic targeting of ligand-dependent Hh signaling in human cancers with somatic mutations in both TP53 and RB1.

Type Journal
ISBN 1558-8238 (Electronic) 0021-9738 (Linking)
Authors Cochrane, C. R.; Vaghjiani, V.; Szczepny, A.; Jayasekara, W. S. N.; Gonzalez-Rajal, A.; Kikuchi, K.; McCaughan, G. W.; Burgess, A.; Gough, D. J.; Watkins, D. N.; Cain, J. E.
Responsible Garvan Author Dr Alvaro Gonzalez Rajal
Published Date 2020-08-31
Published Volume 130
Published Issue 8
Published Pages 4006-4018
Status Published in-print
DOI 10.1172/JCI132513
URL link to publisher's version
OpenAccess link to author's accepted manuscript version