Abstract

Small-cell lung cancer (SCLC) is an aggressive neuroendocrine subtype of lung cancer for which there is no effective treatment1,2. Using a mouse model in which deletion of Rb1 and Trp53 in the lung epithelium of adult mice induces SCLC3,4, we found that the Hedgehog signaling pathway is activated in SCLC cells independently of the lung microenvironment. Constitutive activation of the Hedgehog signaling molecule Smoothened (Smo) promoted the clonogenicity of human SCLC in vitro and the initiation and progression of mouse SCLC in vivo. Reciprocally, deletion of Smo in Rb1 and Trp53-mutant lung epithelial cells strongly suppressed SCLC initiation and progression in mice. Furthermore, pharmacological blockade of Hedgehog signaling inhibited the growth of mouse and human SCLC, most notably following chemotherapy. These findings show a crucial cell-intrinsic role for Hedgehog signaling in the development and maintenance of SCLC and identify Hedgehog pathway inhibition as a therapeutic strategy to slow the progression of disease and delay cancer recurrence in individuals with SCLC.

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Acknowledgements

We would like to thank A. Berns (The Netherlands Cancer Institute) and M. Scott (Stanford University) for the Trp53lox and Ptch1lacZ/+ mice, respectively, J. Whitsett (Cincinnati Children's Hospital) for the antibodies to surfactant protein C, C. Janke (Orsay Curie Institute) for antibodies to polyglutamylated tubulin and C.-M. Fan (Carnegie Institution of Washington) for the adenovirally expressed SmoM2 virus, as well as T. Oro, James Kim, Jynho Kim and P. Beachy for helpful discussions throughout the course of this study. We thank R. Toftgård (Karolinska Institute) and K. McGovern at Infinity Pharmaceuticals for their generous gift of the GANT-61 and cyclopamine, respectively, R. Rohatgi for help with the immunoblot analysis and B. Schaffer for help with the cell culture. This work was supported by the Lucile Packard Foundation for Children's Health (J.S.), the Damon Runyon Cancer Research Foundation (J.S.), the American Lung Association (J.S. and K.-S.P.), the Francis Family Foundation (K.-S.P.), the American Cancer Society (J.S.), the Tobacco-Related Disease Research Program of California (J.F.C.), US National Institutes of Health (NIH) National Cancer Institute R01 CA136574 (J.K.C.), the Flight Attendant Medical Research Institute (YCSA 072033) (C.D.P.), NIH 5T32 CA009302-33 (C.O.), the National Health and Medical Research Council of Australia project grants 546024 and 546098 and the Victorian Cancer Agency (D.N.W., L.G.M. and A.S.), the Deutsche Krebshilfe (107954) (R.K.T.), the German Ministry of Science and Education as part of the Nationales Genomforschungsnetz (NGFN-plus) program (01GS08100) (R.K.T.), the Max Planck Society (MIFA NEUR8061) (R.K.T.), the Deutsche Forschungsgemeinschaft (DFG) through Sonderforschungsbereiche (TP6) (R.K.T.), the Ministry for Innovation, Science, Research and Technology of the State of Nordrhein-Westfalen (MIWT, 4000-12 09) (R.K.T.) and by an anonymous foundation to R.K.T.

Author information

Author notes

    • Kwon-Sik Park
    • , Luciano G Martelotto
    • , Craig D Peacock
    •  & Julien Sage

    These authors contributed equally to this work.

Affiliations

  1. Department of Pediatrics, Stanford University, Stanford, California, USA.

    • Kwon-Sik Park
    • , Katie Bernard
    • , Jamie F Conklin
    •  & Julien Sage
  2. Department of Genetics, Stanford University, Stanford, California, USA.

    • Kwon-Sik Park
    • , Moe R Mahjoub
    • , Katie Bernard
    • , Jamie F Conklin
    • , Tim Stearns
    •  & Julien Sage
  3. Monash Institute of Medical Research, Monash University, Clayton, Victoria, Australia.

    • Luciano G Martelotto
    • , Anette Szczepny
    •  & D Neil Watkins
  4. Max Planck Institute for Neurological Research with Klaus-Joachim-Zülch Laboratories of the Max Planck Society and the Medical Faculty of the University of Cologne, University of Cologne, Cologne, Germany.

    • Martin Peifer
    • , Martin L Sos
    •  & Roman K Thomas
  5. Department of Internal Medicine and Center of Integrated Oncology Köln-Bonn, University of Cologne, Cologne, Germany.

    • Martin L Sos
    •  & Roman K Thomas
  6. University of California–San Francisco Department of Pathology, San Francisco, California, USA.

    • Anthony N Karnezis
  7. Department of Biology, Stanford University, Stanford, California, USA.

    • Moe R Mahjoub
    •  & Tim Stearns
  8. Novartis Institutes for Biomedical Research, Cambridge, Massachusetts, USA.

    • Jing Yuan
    • , Ribo Guo
    • , Beatrice Ospina
    • , Marion Dorsch
    •  & Silvia Buonamici
  9. Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia.

    • Jeanette Falzon
    • , Samara Bennett
    •  & Tracey J Brown
  10. Sidney Kimmel Cancer Centre, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.

    • Ana Markovic
    • , Wendy L Devereux
    •  & Craig D Peacock
  11. Department of Chemical and Systems Biology, Stanford University, Stanford, California, USA.

    • Cory A Ocasio
    •  & James K Chen
  12. Laboratory of Translational Cancer Genomics, Center of Integrated Oncology Köln-Bonn, University of Cologne, Cologne, Germany.

    • Roman K Thomas

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Contributions

A.N.K. analyzed the histopathology of all mouse lung tumors and edited the manuscript. A.S. performed and analyzed the immunohistochemistry. D.N.W. and L.G.M. edited the manuscript and analyzed the immunohistochemistry. L.G.M. performed experiments with Smo inhibitors and chemotherapy in culture and in xenografts. C.A.O. and J.K.C. generated HPI-1 for cell culture experiments. J.K.C. edited the manuscript. M.R.M. and T.S. designed, performed and analyzed the experiments related to the primary cilia in mouse cells. M.P., M.L.S. and R.K.T. designed and performed the experiments related to the genomic analysis of mouse and human tumors. K.-S.P. and K.B. quantified the proliferation and survival phenotypes in tumors treated with cyclopamine. K.-S.P. and J.F.C. analyzed gene and protein expression levels in tumor cells. K.-S.P. performed all the other experiments involving mouse cells. K.-S.P. and J.S. designed the experiments for the analysis of mouse SCLC cells in culture and in vivo, and generated the corresponding figures. C.D.P. designed and analyzed the research performed by A.M. and W.L.D. on the human SCLC cells in vitro. J.F., S.Buonamici, S. Bennett, J.Y., R.G., B.O., M.D., A.M., W.L.D. and T.J.B. designed and performed in vivo xenograft experiments and analyzed the data. K.-S.P., J.S., C.D.P. and S.B. wrote and edited the manuscript.

Competing interests

D.N.W. is a co-inventor on a patent application for the use of Smo antagonists in SCLC. J.K.C. has consulted for Fate Therapeutics, and J.S. has consulted for Infinity Pharmaceuticals. R.K.T. received consulting and lecture fees (from Sequenom, Sanofi-Aventis, Merck, Roche, Infinity, Boehringer, AstraZeneca and ATLAS Biolabs) as well as research support (from Novartis and AstraZeneca). S.B., J.Y., B.O. and R.G. are employees of Novartis Institute of BioMedical Research. M.D. is an employee of Sanofi-aventis.

Corresponding authors

Correspondence to Craig D Peacock or Julien Sage.

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DOI

https://doi.org/10.1038/nm.2473

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