LZTR1 inactivation promotes MAPK/ ERK pathway activation in glioblastoma by stabilizing oncoprotein RIT1

Large-scale sequencing studies on glioblastoma have identified numerous genetic alterations. Leucine-zipper-like transcription regulator 1 ( LZTR1 ) is inactivated by non-synonymous mutations and copy number losses, suggesting that it is a tumor suppressor in glioblastoma. However, how LZTR1 mutations contribute to glioblastoma pathogenesis remains poorly understood. Here, we revealed that LZTR1, as an adaptor of the CUL3 E3 ubiquitin ligase complex, recognizes and triggers ubiquitin-dependent degradation of oncoprotein RIT1, a RAS-like GTPase. Wild-type LZTR1 suppresses glioblastoma cell proliferation and migration by inactivating the MAPK/ERK signaling pathway in a RIT1-dependent manner. However, the effects were abrogated by the glioblastoma-associated LZTR1 mutations. Our findings revealed the underlying molecular mechanism of LZTR1 mutations-driven glioblastoma, and provide novel therapeutic target for LZTR1 mutations-driven glioblastoma. * ### ABBREVIATIONS LZTR1 : leucine-zipper-like transcription regulator 1 RIT1 : RAS-like without CAAX1 ATCC : American Type Culture Collection siRNA : small interfering RNA shRNA : short hairpin RNA CCK-8 : Cell Counting Kit-8 qRT-PCR : quantitative real-time polymerase chain reaction BLI : bioluminescence imaging IP : immunoprecipitation DN : dominant negative OS : overall survival PFS : progression-free survival TCGA : the cancer genome atlas CGGA : Chinese glioma genome atlas GBM : glioblastoma