Flow perfusion effects on three-dimensional culture and drug sensitivity of Ewing sarcoma

Abstract

Three-dimensional tumor models accurately describe different aspects of the tumor microenvironment and are readily available for mechanistic studies of tumor biology and for drug screening. Nevertheless, these systems often overlook biomechanical stimulation, another fundamental driver of tumor progression. To address this issue, we cultured Ewing sarcoma (ES) cells on electrospun poly(e-caprolactone) 3D scaffolds within a flow perfusion bioreactor. Flow-derived shear stress provided a physiologically relevant mechanical stimulation that significantly promoted insulin-like growth factor-1 (IGF1) production and elicited a superadditive release in the presence of exogenous IGF1. This finding is particularly relevant, given the central role of the IGF1/IGF-1 receptor (IGF-1R) pathway in ES tumorigenesis and as a promising clinical target. Additionally, flow perfusion enhanced in a rate-dependent manner the sensitivity of ES cells to IGF-1R inhibitor dalotuzumab (MK-0646) and showed shear stress-dependent resistance to the IGF-1R blockade. This study demonstrates shear stressdependent ES cell sensitivity to dalotuzumab, highlighting the importance of biomechanical stimulation on ES-acquired drug resistance to IGF-1R inhibition. Furthermore, flow perfusion increased nutrient supply throughout the scaffold, enriching ES culture over static conditions. Our use of a tissue-engineered model, rather than human tumors or xenografts, enabled precise control of the forces experienced by ES cells, and therefore provided at least one explanation for the remarkable antineoplastic effects observed by some ES tumor patients from IGF-1R targeted therapies, in contrast to the lackluster effect observed in cells grown in conventional monolayer culture. T he ability to treat cancer patients is critically dependent upon a robust drug discovery pipeline and an efficient method to select the most promising drug candidates for clinical trial advancement. Preclinical drug screening typically relies on the use of 2D culture systems, which are reproducible, fast, and inexpensive. Nevertheless, tumor phenotype is dictated by its interaction with the surrounding 3D microenvironment (1). The inability of 2D systems to mimic this key element has generally resulted in preclinical findings that overstate drug activity when subsequently tested in human clinical trials, therefore undermining the drug discovery process in cancer therapies (2).To overcome these issues, several 3D tumor models have been proposed, including tumor spheroids and hydrogel systems, which attempt to recapitulate heterotypic interactions either between tumor and stroma or tumor and extracellular matrix (ECM), respectively (3, 4). These systems have begun to bridge the gap between in vitro and in vivo testing in several aspects, such as cell growth (5), gene expression pattern (6), and chemoresistance (7). However, these models are still unable to recapitulate and adequately examine the effects of other cues present in the tumor microenvironment, such as heterotypic cell−cell...

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Heralding a new paradigm in 3D tumor modeling

“…In a recent study, Santoro et al cultured Ewing sarcoma cells on an electrospun polymeric scaffold within a flow perfusion bioreactor and showed that flow-derived shear stress significantly enhanced the production of insulin-like growth factor-1 (IGF-1) over static conditions [143]; the IGF1/IGF-1 receptor pathway is a current clinical target for this pediatric disease. It was further demonstrated that drug response to an IGF-1 receptor inhibitor, dalotuzumab, was dependent on flow rate, underscoring the importance of mechanical stimulation on the cancer cell phenotype and drug sensitivity.…”

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