@article{1eb71029a27b49d4a533b6f30adca07a,
title = "Novel mtorc1 inhibitors kill glioblastoma stem cells",
abstract = "Glioblastoma (GBM) is an aggressive tumor of the brain, with an average post-diagnosis survival of 15 months. GBM stem cells (GBMSC) resist the standard-of-care therapy, temozolomide, and are considered a major contributor to tumor resistance. Mammalian target of rapamycin Complex 1 (mTORC1) regulates cell proliferation and has been shown by others to have reduced activity in GBMSC. We recently identified a novel chemical series of human-safe piperazine-based brain-penetrant mTORC1-specific inhibitors. We assayed the piperazine-mTOR binding strength by two biophysical measurements, biolayer interferometry and field-effect biosensing, and these confirmed each other and demonstrated a structure–activity relationship. As mTORC1 is altered in human GBMSC, and as mTORC1 inhibitors have been tested in previous GBM clinical trials, we tested the killing potency of the tightest-binding piperazines and observed that these were potent GBMSC killers. GBMSCs are resistant to the standard-of-care temozolomide therapy, but temozolomide supplemented with tight-binding piperazine meclizine and flunarizine greatly enhanced GBMSC death over temozolomide alone. Lastly, we investigated IDH1-mutated GBMSC mutations that are known to affect mitochondrial and mTORC1 metabolism, and the tight-binding meclizine provoked {\textquoteleft}synthetic lethality{\textquoteright} in IDH1-mutant GBMSCs. In other words, IDH1-mutated GBMSC showed greater sensitivity to the coadministration of temozolomide and meclizine. These data tend to support a novel clinical strategy for GBM, i.e., the co-administration of meclizine or flunarizine as adjuvant therapy in the treatment of GBM and IDH1-mutant GBM.",
keywords = "Glioblastoma, Meclizine, MTOR, MTORC1, Piperazine",
author = "Sandoval, {Jose A.} and Alexey Tomilov and Sandipan Datta and Sonia Allen and Robert O{\textquoteright}Donnell and Thomas Sears and Woolard, {Kevin D} and Dmytro Kovalskyy and Angelastro, {James M.} and Gino Cortopassi",
note = "Funding Information: The GBMSC lines used were patient-derived from recurring tumors and gifted to us by Kevin Woolard DVM, PhD from the University of California Davis. The cell lines were named 0827 and 0923. 0827 is the only IDH1 WT cell line used in the main figures in the manuscript and is referred to as IDH1 wildtype in Figure 6. 923 is used only in appendix and is referred to as “IDH1 WT” in Appendix A Figure A1 and “GB SC 2” in Appendix A Figure A2. The 0827 and 923 GBM stem cells were cultured in Neurobasal A minimal media with 1X N-2 supplement, 1X B-27 supplement, 1X GlutaMAX, and (50 units/mL of penicillin/50 µg/mL of streptomycin) from Gibco (Gaithersburg, MD, USA), and human EGF and FGF-154 from Shenandoah Biotechnology (Warwick, PA, USA). The IDH1 mutant cell line was named 905 and will be referred to as IDH1 mutant or R132H IDH1 mutant. It is the only IDH1 mutant cell line used in the main figures. The IDH1 mutant Grade III astrocytoma was named BT 142 and is only used in the appendix figures. It is referred to as “IDH1 mutant” in Appendix A Figure A1 and “IDH1 mt 2” in Appendix A Figure A2. These cells were cultured in the same media as the IDH1 wildtype with the addition of 1 mL of 10 µg/mL PDGF. Cells used did not exceed passage 15. Patient-derived glioma stem cells were generated at the National Cancer Institute, National Institutes of Health (Bethesda, MD). This research was supported by the Intramural Research Program of the NIH, National Cancer Institute, Center for Cancer Research and approved by the Institutional Review Board [48,49]. The stemness profile of IDH1 wildtype cells are included as a appendix figure (Figure A3). GBM-differentiated cells were cultured in Dulbecco{\textquoteright}s modified Eagle{\textquoteright}s medium (DMEM) supplemented with 10% FBS and pen/strep. Funding Information: Funding: This research received support from P30CA093373 to UCDMC. Presented work was supported by",
year = "2020",
month = dec,
doi = "10.3390/ph13120419",
language = "English (US)",
volume = "13",
pages = "1--18",
journal = "Pharmaceuticals",
issn = "1424-8247",
publisher = "Multidisciplinary Digital Publishing Institute (MDPI)",
number = "12",
}