Ubiquitin carboxyl-terminal esterase L1 (UCHL1) is associated with stem-like cancer cell functions in pediatric high-grade glioma

Abstract

Pediatric high-grade gliomas represent 8–12% of all primary tumors of the nervous system in children. Five-year survival for these pediatric aggressive tumors is poor (15–35%) indicating the need to develop better treatments for pediatric high-grade gliomas. In this work we used SF188 and SJ-GBM2 cell lines to study the function of the ubiquitin carboxyl-terminal esterase L1 (UCHL1), a deubiquitinase de-regulated in several cancers, in pediatric high-grade gliomas. UCHL1 depletion in SF188 and SJ-GBM2 glioma cells was associated with decreased cell proliferation and invasion, along with a reduced ability to grow in soft agar and to form spheres (i.e. self-renewal measure). A 70% reduction in Wnt signaling was also observed in the SF188 and SJ-GBM2 UCHL1 knockdowns (KDs) using a TCF-dependent TOPflash reporter assay. Transcriptome comparisons of UCHL1 KDs versus vector control identified a list of 306 differentially expressed genes (at least 2-fold change; p <0.05) which included genes known to be involved in cancer like ACTA2, POSTN, LIF, FBXL7, FBXW11, GDF15, HEY2, but also potential novel genes such us IGLL5, ABCA4, AQP3, AQP4, CALB1, and ALK. Bioinformatics gene ontology (GO) analysis of these 306 genes revealed significant enrichment in “signal peptides”, “extracellular matrix”and “secreted proteins” GO Terms. “Angiogenesis and blood vessel development”, “neuron differentiation/development”, cell adhesion”, and “cell migration” also showed significant enrichment in our GO analysis. Top canonical pathways identified by Ingenuity Pathway Analysis (IPA) included “Clathrin-mediated Endocytosis Signaling” (p = 5.14x10-4), “Virus Entry via Endocytic Pathways” (p = 6.15x 10−4), and “High Mobility Group-Box 1 (HMGB1) Signaling” (p = 6.15x10-4). While FGF2, IL1B, TNF and PDGFB were predicted as top upstream regulators (p < 2x10-16) of the UCHL1 KD-associated transcriptome. Aberrant expression of UCHL1 in pediatric high-grade gliomas may promote cell invasion, transformation, and self-renewal properties, at least in part, by modulating Wnt/Beta catenin activity. UCHL1 might act as an oncogene in glioma within the gene network that imparts stem-like characteristics to these cancer cells.

Ubiquitin C‐Terminal Hydrolase L1: Biochemical and Cellular Characterization of a Covalent Cyanopyrrolidine‐Based Inhibitor

“…As one of the most abundant soluble proteins in the brain, it has been linked to the progression of Alzheimer's and Parkinson's disease . There is also strong evidence supporting UCHL1 as an oncogene in various cancers including glioblastoma, small‐cell lung cancer, and blood cancers, among others . In particular, increased UCHL1 levels in these cancers correlates with increased invasiveness and metastatic behavior as well as poor patient prognosis .…”

Emerging role of F-box proteins in the regulation of epithelial-mesenchymal transition and stem cells in human cancers

“…Ueda et al reported that Fbxl10 overexpression in murine hematopoietic stem cells contributed to leukemia via upregulation of Nsg2 (neuron-specific gene family member 2) and metabolic activation [148]. FBXL7 and FBXW11 are also involved in UCHL1 (ubiquitin carboxyl-terminal esterase L1)-mediated stem-like cancer cell function in high-grade glioma [149].…”

Nrf2 inhibition affects cell cycle progression during early mouse embryo development

“…Recent studies have verified that brusatol may selectively and transiently inhibit Nrf2 signaling pathway and that the degradation of Nrf2 protein may serve as the major mechanism responsible for antineoplastic effects [ 15 ]. Ubiquitin C-terminal hydrolase L1 (UCHL1) is a deubiquitinating enzyme of the ubiquitin proteasome system and its depletion is associated with decreased cell proliferation [ 16 ].…”