Abstract 2998: Linear confined space migration induces treatment resistance and gene expression changes in glioblastoma multiforme

Abstract

Abstract Background: Glioblastoma Multiforme (GBM), an aggressive brain cancer, is known for its treatment resistant recurrence and lethality. The diffuse migration and invasion of GBM cells commonly occurs along brain white matter tracts in linear confined spaces between axons and has significant clinical implications as these cells survive initial therapies forming the main source of recurrent tumors resistant to therapies. In this context, this project aims to analyze the treatment resistance mechanism associated with linear confined space migrating cells (LCSM) to devise a better treatment strategy for GBM. Methods: We used a combination of microfluidic technology (5 µM wide channels in PDMS block) emulating linear white matter tracts in brain and standard molecular analysis (confocal microscopy, high content imaging, western blot, and flow cytometry) to investigate LCSM cells compared to Standard Monolayer Culture cells (SMCs) for the mechanism of drug resistance. Both established and patient derived GBM cell lines were used in the study. Results: LCSM cells were more resistant to chemo-drugs (Temozolomide and Doxorubicin) than SMCs as observed in cell viability assays. Enhanced drug efflux was observed in LCSM cells compared to SMC cells indicating the activation of drug efflux pumps. Protein expression analysis indicated that ABC drug efflux transporters (ABCB1, ABCC1, ABCG2) were activated or enhanced at varying levels in different LCSM cells compared to SMCs. Pharmacological inhibition of the prominently expressed ABCG2 protein using KO143 resulted in enhanced cell death by chemo drugs, suggesting that chemo resistance in LCSM, at least in part, is conferred by ABCG2 or other efflux transporters. In addition, CD133 (a marker of treatment resistant stem cell population in GBM) and AQP4 (Aquaporin 4; pro-migratory marker in GBM) were also enhanced in LCSM compared to SMC suggesting their possible roles in treatment resistance. Conclusion: Preliminary studies reveal that the enhanced expression ABC transporters, prominently ABCG2, might be responsible for enhanced drug efflux and low therapeutic sensitivity in GBM- LCSM cells. The over expression of AQP4 and CD133, and differential expression of other genes suggest that more complex mechanisms might be involved, which are currently under investigation. Citation Format: Anish Babu, Patrick McKernan, Xue Cai, James Battiste. Linear confined space migration induces treatment resistance and gene expression changes in glioblastoma multiforme [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2998.