Abstract
Abstract Lung cancer is the leading cause of cancer deaths worldwide. The LKB1 (STK11) tumor suppressor gene is commonly inactivated in non-small cell lung carcinomas (NSCLC), a major form of lung cancer. Currently, no effective treatments are available for LKB1-inactivated lung cancer. Elucidation of critical signaling downstream of LKB1-inactivation has the potential to uncover rational therapeutic targets for this unique and prevalent molecular subset of lung cancers. In this study, we identified INSL4 (insulin-like 4), a member of the insulin/IGF/relaxin superfamily, as a novel downstream target of LKB1-deficiency through gene expression profiling analysis. We observed that INSL4 expression was highly induced through aberrant CRTC-CREB activation subsequent to LKB1 inactivation. INSL4 was highly expressed in human LKB1-deficient NSCLC cells and primary tumors while undetectable in all normal tissues except in the placenta. High INSL4 expression was associated with more advanced lung cancer and worse patient survival. INSL4 depletion inhibited the growth and viability of LKB1-null NSCLC cells in vitro and blocked the growth of lung cancer xenografts. Moreover, expression profiling identified an INSL4-regulated gene program that is associated with the regulation of cell cycle, growth, and survival. In conclusion, LKB1 deficiency induces an autocrine INSL4 signaling that critically supports the growth and survival of lung cancer cells. Therefore, aberrant INSL4 signaling is a promising therapeutic target for LKB1-deficient lung cancers. Citation Format: Rongqiang Yang, Steven W. Li, Zirong Chen, Xin Zhou, Wei Ni, Dongtao A. Fu, Jianrong Lu, Frederic J. Kaye, Lizi Wu. LKB-inactivated lung cancer cells exhibit dependency on INSL4 signaling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 392.
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