Oncogenomics of c-Myc transgenic mice reveal novel regulators of extracellular signaling, angiogenesis and invasion with clinical significance for human lung adenocarcinoma
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Yari Ciribilli1,2 and Jürgen Borlak2
1Centre for Integrative Biology (CIBIO), University of Trento, 38123 Povo (TN), Italy
2Centre for Pharmacology and Toxicology, Hannover Medical School, 30625 Hannover, Germany
Jürgen Borlak, email: Borlak.Juergen@mh-hannover.de
Keywords: c-Myc transgenic mouse model of lung cancer, papillary adenocarcinomas, whole genome scans, c-Myc regulatory gene networks, c-Myc targeted regulators of extracellular signaling
Received: June 26, 2017 Accepted: September 21, 2017 Published: October 23, 2017
The c-Myc transcription factor is frequently deregulated in cancers. To search for disease diagnostic and druggable targets a transgenic lung cancer disease model was investigated. Oncogenomics identified c-Myc target genes in lung tumors. These were validated by RT-PCR, Western Blotting, EMSA assays and ChIP-seq data retrieved from public sources. Gene reporter and ChIP assays verified functional importance of c-Myc binding sites. The clinical significance was established by RT-qPCR in tumor and matched healthy control tissues, by RNA-seq data retrieved from the TCGA Consortium and by immunohistochemistry recovered from the Human Protein Atlas repository. In transgenic lung tumors 25 novel candidate genes were identified. These code for growth factors, Wnt/β-catenin and inhibitors of death receptors signaling, adhesion and cytoskeleton dynamics, invasion and angiogenesis. For 10 proteins over-expression was confirmed by IHC thus demonstrating their druggability. Moreover, c-Myc over-expression caused complete gene silencing of 12 candidate genes, including Bmp6, Fbln1 and Ptprb to influence lung morphogenesis, invasiveness and cell signaling events. Conversely, among the 75 repressed genes TNFα and TGF-β pathways as well as negative regulators of IGF1 and MAPK signaling were affected. Additionally, anti-angiogenic, anti-invasive, adhesion and extracellular matrix remodeling and growth suppressive functions were repressed. For 15 candidate genes c-Myc-dependent DNA binding and transcriptional responses in human lung cancer samples were confirmed. Finally, Kaplan–Meier survival statistics revealed clinical significance for 59 out of 100 candidate genes, thus confirming their prognostic value.
In conclusion, previously unknown c-Myc target genes in lung cancer were identified to enable the development of mechanism-based therapies.
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