Abstract
Pulmonary neuroendocrine (NE) cancer, including small cell lung cancer (SCLC), is a particularly aggressive malignancy. The lineage-specific transcription factors Achaete-scute homolog 1 (ASCL1), NEUROD1 and POU2F3 have been reported to identify the different subtypes of pulmonary NE cancers. Using a large-scale mass spectrometric approach, here we perform quantitative secretome analysis in 13 cell lines that signify the different NE lung cancer subtypes. We quantify 1,626 proteins and identify IGFBP5 as a secreted marker for ASCL1High SCLC. ASCL1 binds to the E-box elements in IGFBP5 and directly regulates its transcription. Knockdown of ASCL1 decreases IGFBP5 expression, which, in turn, leads to hyperactivation of IGF-1R signaling. Pharmacological co-targeting of ASCL1 and IGF-1R results in markedly synergistic effects in ASCL1High SCLC in vitro and in mouse models. We expect that this secretome resource will provide the foundation for future mechanistic and biomarker discovery studies, helping to delineate the molecular underpinnings of pulmonary NE tumors.
Highlights
Pulmonary neuroendocrine (NE) cancer, including small cell lung cancer (SCLC), is a aggressive malignancy
To comprehensively analyze the secretome of high-grade NE-lung cancer, we sought to profile the secreted proteins in the conditioned media (CM) from a panel of 13 human lung cancer cell lines (Fig. 1a). This panel was composed of the following cell lines that signify the normal/different subtypes of NE-lung cancers: (1) a human bronchial epithelial cell line HBEC34-KT that is characterized by a number of properties consistent with untransformed epithelial cells, including: normal epithelial morphology, expression of epithelial markers, lacking anchorage-independent growth and inability to form tumors in vivo[24]; (2) HCC4018; (3) additional ASCL1High SCLC lines (n = 6, H2081, H889, H1092, H69, H2107, H128); (4) NEUROD1High SCLC lines (n = 5, H378, H82, H2171, HCC970, H524)
H2081 cells treated with DMSO, JQ-1 (1 μM for 48 h) and iBET-762 (2 μM for 48 h). b Immunoblotting analyses of indicated antibodies in H2081 cells transfected with empty vector or Myc-Achaete-scute homolog 1 (ASCL1) for 40 h, treated with DMSO or JQ-1 (1 μM for 48 h). c Immunoblotting analysis of IGF-1-induced IGF-1R activation in H2081 treated as indicated
Summary
Pulmonary neuroendocrine (NE) cancer, including small cell lung cancer (SCLC), is a aggressive malignancy. Recent studies have indicated that there is considerable heterogeneity among SCLCs in terms of expression of lineage-specific oncogenes (e.g., ASCL1, NEUROD1 and POU2F3)[5,9,10,11], histology[12], growth characteristics[13], expression of NE cell differentiation markers[5,10], MYC family member activation[14], and mechanisms of Notch pathway inactivation[15,16] These findings point to the critical need for better classification of the different SCLC subtypes, and more personalized treatment regimens. Recent advances in cancer cell secretome analysis showed the application of the proteomic approaches for the identification of secreted proteins[21,22]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
