Abstract 40: Biomaterials and systems biology to guide breast cancer drug screening

Improved in vitro models are needed to better understand cancer progression and bridge the gap between in vitro proof-of-concept studies, in vivo validation, and clinical application. Many methods exist to create biomaterial platforms, including hydrogels, which we use to study cells in contexts more akin to what they experience in vivo. Our lab has multiple approaches to create such biomaterials, based on combinations of poly(ethylene glycol) (PEG) with peptides and zwitterions. In this presentation, I will discuss our findings in using these cell culture environments to understand the role of the extracellular matrix (ECM) in controlling cancer cell innate drug response via adaptive signaling. Specifically, I will present data comparing the behavior of breast, prostate, and ovarian cancer cells to chemotherapy and targeted drugs when cultured as 3D spheroids, on 2D gels, and as a function of the stiffness of the tumor microenvironment. This approach uncovered that cells on 2D hydrogels and spheroids encapsulated in 3D hydrogels were less responsive to receptor tyrosine kinase (RTK)-targeting drugs sorafenib and lapatinib, but not cytotoxic drugs, compared to single cells in hydrogels and cells on plastic. We found that transcriptomic differences between these in vitro models and tumor xenografts did not reveal mechanisms of ECM-mediated resistance to sorafenib. However, a systems biology analysis of phospho-kinome data uncovered that variation in MEK phosphorylation was associated with RTK-targeted drug resistance. Using sorafenib as a model drug, we found that co-administration with a MEK inhibitor decreased ECM-mediated resistance in vitro and reduced in vivo tumor burden compared to sorafenib alone. In sum, we provide a novel strategy for identifying and overcoming ECM-mediated resistance mechanisms by performing drug screening, phospho-kinome analysis, and systems biology across multiple biomaterial environments. Our work suggests that different model systems are important for evaluating cell response to receptor tyrosine kinase inhibitors, whose efficacy depends on cell-ECM interactions. Citation Format: Alyssa Schwartz, Lauren Barney, Lauren Jansen, Christopher Hall, Aaron Meyer, Shelly R. Peyton. Biomaterials and systems biology to guide breast cancer drug screening [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):A