A crucial requirement for Hedgehog signaling in small cell lung cancer

Abstract

The authors find that cell-intrinsic activation of Hedgehog signaling without genetic alterations is a contributing feature to the progression and chemotherapy resistance of small-cell lung carcinoma, and that Hedgehog inhibition can prevent lung cancer growth and recurrence. 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.