title: Human recombinant arginase I (Co)-PEG5000 [HuArgI (Co)-PEG5000]-induced arginine depletion is selectively cytotoxic to human glioblastoma cells.
abstract: In this study, we attempt to target Arginine auxotrophy in glioblastoma multiforme (GBM) cells using a pegylated recombinant human Arginase I cobalt [HuArgI (Co)-PEG5000]. We tested and characterized the activity of HuArgI (Co)-PEG5000 on a panel of 9 GBM cell lines and on human fetal glial cells (SVG-p12). HuArgI (Co)-PEG5000 was cytotoxic to all GBM cells tested. SVG-p12 cells were not sensitive demonstrating the selective cytotoxicity of HuArgI (Co)-PEG5000-induced arginine deprivation. Addition of L-citrulline led to the rescue of 6 GBM cell lines but only at concentrations of 11.4 mM, reflecting the extent of arginine auxotrophy in GBM. The ability of L-citrulline to rescue cells was dependent on the expression of argininosuccinate synthetase-1 (ASS1) with the cells that were not rescued by L-citrulline being negative for ASS1 expression. Knocking-down ASS1 reversed the ability of L-citrulline to rescue GBM cells, further illustrating the dependence of arginine auxotrophy on ASS1 expression. Inhibition of autophagy increased cell sensitivity to HuArgI (Co)-PEG5000 indicating that, following arginine deprivation, autophagy plays a protective role in GBM cells. Analysis of the type of cell death revealed a lack of AnnexinV staining and caspase activation in HuArgI (Co)-PEG5000-treated cells, indicating that arginine deprivation induces caspase-independent, non-apoptotic cell death in GBM. We have shown that GBM cells are auxotrophic for arginine and can be selectively targeted using HuArgI (Co)-PEG5000-induced arginine depletion, thus demonstrating that L-Arginine deprivation is a potent and selective potential treatment for GBM.
authors.affiliation: Department of Natural Sciences, School of Arts and Sciences, Lebanese American University, Beirut, 1102 2801, Lebanon.
authors.forename: Oula
authors.initials: O
authors.lastname: Khoury
authors.forename: Noura
authors.initials: N
authors.lastname: Ghazale
authors.forename: Everett
authors.initials: E
authors.lastname: Stone
authors.forename: Mirvat
authors.initials: M
authors.lastname: El-Sibai
authors.forename: Arthur E
authors.initials: AE
authors.lastname: Frankel
authors.forename: Ralph J
authors.initials: RJ
authors.lastname: Abi-Habib
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D001119:Arginase / Q000494:pharmacology*; D001120:Arginine / Q000378:metabolism*; D001124:Argininosuccinate Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D001343:Autophagy; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D005434:Flow Cytometry; D005909:Glioblastoma / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D011092:Polyethylene Glycols / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured
chemical_list: D011994:Recombinant Proteins; D011092:Polyethylene Glycols; D001120:Arginine; C574619:ARG1 protein, human; D001119:Arginase; C572759:HuArgI (Co)-PEG5000; D001124:Argininosuccinate Synthase