3D Tissue-Engineered Tumor Model for Ewing’s Sarcoma That Incorporates Bone-like ECM and Mineralization

The tumor microenvironment harbors essential components
required
for cancer progression including biochemical signals and mechanical
cues. To study the effects of microenvironmental elements on Ewing’s
sarcoma (ES) pathogenesis, we tissue-engineered an acellular three-dimensional
(3D) bone tumor niche from electrospun poly­(ε-caprolactone)
(PCL) scaffolds that incorporate bone-like architecture, extracellular
matrix (ECM), and mineralization. PCL-ECM constructs were generated
by decellularizing PCL scaffolds harboring cultures of osteogenic
human mesenchymal stem cells. The PCL-ECM constructs simulated in
vivo-like tumor architecture and increased the proliferation of ES
cells compared to PCL scaffolds alone. Compared to monolayer controls,
3D environments facilitated the downregulation of the canonical insulin-like
growth factor 1 receptor (IGF-1R) signal cascade through mechanistic
target of rapamycin (mTOR), both of which are targets of recent clinical
trials. In addition to the downregulation of canonical IGF-1R signaling,
3D environments promoted a reduction in the clathrin-dependent nuclear
localization and transcriptional activity of IGF-1R. In vitro drug
testing revealed that 3D environments generated cell phenotypes that
were resistant to mTOR inhibition and chemotherapy. Our versatile
PCL-ECM constructs allow for the investigation of the roles of various
microenvironmental elements in ES tumor growth, cancer cell morphology,
and induction of resistant cell phenotypes.