Genetic modifiers of EGFR dependence in non-small cell lung cancer

Abstract

Lung adenocarcinomas harboring activating mutations in the epidermal growth factor receptor (EGFR) represent a common molecular subset of non-small cell lung cancer (NSCLC) cases. EGFR mutations predict sensitivity to EGFR tyrosine kinase inhibitors (TKIs) and thus represent a dependency in NSCLCs harboring these alterations, but the genetic basis of EGFR dependence is not fully understood. Here, we applied an unbiased, ORF-based screen to identify genetic modifiers of EGFR dependence in EGFR-mutant NSCLC cells. This approach identified 18 kinase and kinase-related genes whose overexpression can substitute for EGFR in EGFRdependent PC9 cells, and these genes include seven of nine Src family kinase genes, FGFR1, FGFR2, ITK, NTRK1, NTRK2, MOS, MST1R, and RAF1. A subset of these genes can complement loss of EGFR activity across multiple EGFR-dependent models. Unbiased gene-expression profiling of cells overexpressing EGFR bypass genes, together with targeted validation studies, reveals EGFRindependent activation of the MEK-ERK and phosphoinositide 3-kinase (PI3K)-AKT pathways. Combined inhibition of PI3K-mTOR and MEK restores EGFR dependence in cells expressing each of the 18 EGFR bypass genes. Together, these data uncover a broad spectrum of kinases capable of overcoming dependence on EGFR and underscore their convergence on the PI3K-AKT and MEK-ERK signaling axes in sustaining EGFR-independent survival. epidermal growth factor receptor | non-small cell lung cancer | ORF

Ex vivo model of non‑small cell lung cancer using mouse lung epithelial cells

“…4B). These results are consistent with the idea that Kras activates MAPK signaling downstream of EGFR, making cells resistant to EGFR inhibition and that transformation by EGFR ex19del requires its kinase activity and downstream MAPK signaling (17). Overall, these results show that transformed LE cells are addicted to oncogenic Kras-or EGFR-stimulated signaling.…”

High-throughput Phenotyping of Lung Cancer Somatic Mutations

“…First, we leveraged a recently developed erlotinib-rescue assay in PC9 lung adenocarcinoma cells (Sharifnia et al, 2014) to determine which mutations represent gain-of-function mutations that are epistatic to EGFR. PC9 cells harbor an activating EGFR exon 19 in-frame deletion and are naturally sensitive to the EGFR inhibitor erlotinib.…”

“…PC9 cells harbor an activating EGFR exon 19 in-frame deletion and are naturally sensitive to the EGFR inhibitor erlotinib. Expression of variants such as mutant KRAS that re-activate downstream signaling pathways can rescue the erlotinib-induced lethality in this cell type (Sharifnia et al, 2014). …”

A genetic interaction analysis identifies cancer drivers that modify EGFR dependency

“…This is supported by existing evidence of genetic interactions of EGFR with other drivers of tumorigenesis (Sharifnia et al 2014). For example, patients bearing EGFR mutations are known to evolve resistance to EGFRi therapies by virtue of mutations in other cancer drivers.…”