Patients with non-small cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) gene mutations
have been successfully treated with EGFR tyrosine kinase inhibitors (EGFR-TKIs). Osimertinib has emerged as
one of the preferred front-line agents given the significant improvement in progression-free survival and overall
survival. However, the majority of patients will develop acquired resistance to this targeted therapy. Osimertinib
is effective in combination with MEK/ERK signaling inhibitions in overcoming and even delaying acquired
resistance to osimertinib in pre-clinical studies. Single-cell molecular profiling has identified that YAP inhibitors
may overcome acquired resistance to osimertinib, even after exposure to MEK/ERK inhibitions. Bulk molecular
assays and single-cell RNA-seq methods have been the mainstream approaches to evaluating the signaling
alterations in cultures and tissues. However, there is little known about spatially resolved single-cell and
subcellular details of signaling networks and interactions in NSCLCs. Recently, the rapid multiplexed
immunofluorescence (RapMIF) assay (developed by the Pl) revealed the effect of osimertinib on the subcellular
organization of signaling protein factors. To further evaluate the protein-protein interactions in NSCLC cells and
tissues, this proposal will establish rapid multiplexed protein interaction (RapMPI) method to study drug-sensitive
and resistant human cell lines in cultures and tissues from cell line-derived xenografts in mice and patient-derived
xenografts (PDXs) with EGFR mutations (EGFRm). RapMPI will be optimized using automated labeling,
multiplexing chemistry, and signaling interactome reconstructions. This project tests the hypotheses that single
cell and spatial signaling networks and interaction maps will quantitatively model MEK/ERK upstream' s crosstalk
with YAP's upstream to define 20 pre-selected protein pair interactions for rationally designed combination
therapies to overcome acquired resistance to osimertinib. Aim 1 will map out spatial signaling interactors and
their subcellular localization on major organelles using RapMPI in drug-sensitive and resistant EGFRm cells
under control, osimertinib treatment only, MEKIERK, or YAP inhibition only, and osimertinib combined with
MEKIERK or YAP inhibition conditions. Aim 2 will then measure spatial signaling interactome using RapMPI in
vivo using MEK/ERK or YAP inhibitors in combination with osimertinib in mouse xenograft and PDX models (pretreatment,
1-week, 1-month, and until resistance occurs, n=5 each) and EGFRm human tissues with osimertinib-responsive
or resistance clinical outcome (n=10 each). The long-term goal of this R33 is to uncover the spatially
and temporally coordinated acquired resistance using the subcellular and cellular signaling network maps. This
R33 is innovative because ii establishes an emerging subcellular image-based signaling analysis technology to
guide rationally designed combinatorial intervention for overcoming resistance to osimertinib. The proposed work
is significant because it generates new knowledge on compensatory signaling networks in NSCLCs at the
highest molecular resolution on a single cell basis otherwise not attainable by bulk signaling protein assays.