Driver mutations in major lung cancer oncogenes can be analyzed in Drosophila models

Lung cancer remains the leading cause of cancer-associated mortality. Despite recent promising achievements, the overall prognosis remains very poor. In order to integrate the advantages of adapted, transgenic animal models with a high-throughput procedure on the one hand and compliance with the 3R principles on the other hand, we have established and evaluated appropriate Drosophila models. To achieve this goal, we ectopically expressed oncogenes representing the most important driver mutations exclusively in the airway system. These oncogenes were either the human oncogenes or the corresponding Drosophila orthologs. We concentrated on two complementary read-out systems, 1) early larval lethality and 2) quantification of concurrently expressed GFP as a proxy for tumor mass. We could show that ectopic expression of EgfrCA, RasV12, Raf, Rolled (MAPK), PI3K92E, Alk, Akt and Arm can induce early lethality. Thus, they can be used in a straight-forward high-throughput screening approach and can replace mouse models to a considerable extent. Moreover, we could also show that measurement of tumor mass by a concurrently expressed marker (GFP) can be used to detect positive treatment results. Our results show that our Drosophila system provides a superb in vivo inver­tebrate screening system amenable to high-throughput approaches and thus effectively complements the toolbox for the development of novel anti-lung cancer treatments, while complying with the 3R principles.

An EGFR-Induced Drosophila Lung Tumor Model Identifies Alternative Combination Treatments.

Lung cancer is the leading cause of cancer-associated mortality. Mutations in the EGFR gene are among the most important inducers of lung tumor development, but success of personalized therapies is still limited because of toxicity or developing resistances. We expressed constitutively active EGFR (EGFRCA) exclusively in the airway system of Drosophila melanogaster and performed comprehensive phenotyping. Ectopic expression of EGFRCA induced massive hyper- and metaplasia, leading to early death. We used the lethal phenotype as a readout and screened a library of FDA-approved compounds and found that among the 1,000 compounds, only the tyrosine kinase inhibitors (TKI) afatinib, gefitinib, and ibrutinib rescued lethality in a whole-animal screening approach. Furthermore, we screened the library in the presence of a subtherapeutic afatinib dose and identified bazedoxifene as a synergistically acting compound that rescues EGFR-induced lethality. Our findings highlight the potential of Drosophila-based whole-animal screening approaches not only to identify specific EGFR inhibitors but also to discover compounds that act synergistically with known TKIs. Moreover, we showed that targeting the EGFR together with STAT-signaling is a promising strategy for lung tumor treatment.