(69f) Sprouty2 Regulates Signaling and Phenotypic Responses of Glioblastoma Cells to DNA Damaging Agents and Receptor Kinase Inhibitors

Cell signaling mechanisms govern tumor response to approved and investigational therapeutics, including DNA damaging agents and targeted therapeutics such as EGFR and MET kinase inhibitors. Understanding these mechanisms quantitatively is key to improving patient survival, especially in tumors characterized by a high degree of chemoresistance. We previously identified the protein Sprouty2 (SPRY2) as a possible tumor promoter in glioblastoma multiforme (GBM). This discovery was unexpected because SPRY2 functions as a tumor suppressor in other tumor types. Specifically, we found that SPRY2 knockdown reduced proliferation of human GBM cells and antagonized the growth of subcutaneous GBM tumor xenografts in mice. Here, we explored the role of SPRY2 in modulating the response of glioblastoma cells to two different classes of cancer therapeutics: DNA damaging agents, temozolomide and carboplatin, and targeted inhibitors of oncogenic receptor kinases, Gefitinib + PHA665752 (G+P). SPRY2 knockdown increased GBM cell line response to both classes of therapeutics. Thus, the normal expression of SPRY2 in glioblastoma cells antagonizes cell-autonomous responses that would otherwise lead to increased cancer cell death, pointing to SPRY2 as a broad driver of glioblastoma resistance to therapy. We went on to survey dynamic alterations in the DNA damage response, proliferation, and survival signaling pathways. We then modeled the relationships between cell death, cell cycle, and cell signaling using partial least squares regression (PLSR), a data-driven computational modeling approach. Our analysis revealed that a core subset of kinase-driven signaling processes, spanning multiple distinct signaling pathways that are common to the cellular response to both classes of therapeutics, is responsible for explaining how SPRY2 broadly modulates glioblastoma response to therapeutics. In combination with the original DNA damaging and receptor kinase inhibition treatments, we then inhibited these key kinase driven pathways, and observed the expected perturbations in cellular phenotypes. Co-inhibiting kinases identified by the PLSR model to contribute to variability between SPRY2 expressing versus knockdown cells, enhanced cell death and cell cycle arrest. These findings begin to elucidate the mechanism by which SPRY2 may act as a tumor promoter in glioblastoma cells. Ongoing studies aim to identify the molecular SPRY2 interaction partners that are upstream of these resistance mechanisms. Ultimately, this work has the potential to guide the rational combination of several available classes of therapeutics in order to improve glioblastoma patient survival.