Abstract
ABSTRACT
Purpose
Lung metastases are the primary cause of death in osteosarcoma patients and treatment response often vary due to convergence of genetic and phenotypic influences in the context of a dynamic tumor-host tissue environment. The purpose of this study was to determine how dynamic tumor- and host-driven receptor tyrosine kinase (RTK)-ERK signaling interactions contribute to phenotypic drug response heterogeneity.
Experimental Design
Live-cell time-lapse microscopy and data-driven dynamical modeling was used to resolve ERK activity, FOSL1/Fra-1 reporter expression, and spatiotemporal cell fate in living, biosensor-expressing osteosarcoma lung metastases
ex vivo
following MCL1 inhibitor exposure. RTK inhibitors were then evaluated for their ability to suppress adaptive signaling and enhance MCL1 inhibitor efficacy
ex vivo
and
in vivo
.
Results
MCL1 inhibition induced extensive tumor-cell death; however, persistent ERK
high
/Fra-1
high
reporter cells emerged and were enriched at the tumor-lung interface, consistent with adaptive resistance. Experimental and computational approaches revealed that tumor-cell lysis amplified fibroblast growth factor receptor (FGFR)-mediated ERK signaling in neighboring cells, promoting a targetable drug-resistant state marked by adaptive ERK induction, FOSL1/Fra-1 expression, and correlated with upregulation of known drug resistance pathways Nrf2 and HMOX1. Combinatorial inhibition of FGFR with fexagratinib, or broad-spectrum RTK inhibitor, pazopanib, suppressed adaptive ERK activation and enhanced MCL1 inhibitor response resulting in greater efficacy
ex vivo
and
in vivo
.
Conclusions
Tumor-host and tumor-cell-lysis-induced FGFR-ERK signaling contribute to spatiotemporally heterogeneous adaptive resistance in metastatic osteosarcoma. These data support combinatorial targeting of RTK signaling with cytotoxic or targeted agents as a strategy to block adaptive resistance and improve treatment efficacy.