UBE4B levels are correlated with clinical outcomes in neuroblastoma patients and with altered neuroblastoma cell proliferation and sensitivity to epidermal growth factor receptor inhibitors

Abstract

Background The UBE4B gene, located on chromosome 1p36, encodes a ubiquitin ligase that interacts with Hrs, a protein involved in EGFR trafficking, suggesting a link between EGFR trafficking and neuroblastoma pathogenesis. We have analyzed the roles of UBE4B in the outcomes of neuroblastoma patients and in neuroblastoma tumor cell proliferation, EGFR trafficking, and response to EGFR inhibition. Methods We examined the association of UBE4B expression with neuroblastoma patient survival using available microarray datasets. We measured UBE4B and EGFR protein levels in patient tumor samples and EGFR degradation rates in neuroblastoma cell lines and analyzed the effects of UBE4B on neuroblastoma tumor cell growth. The effects of the EGFR inhibitor cetuximab were examined in neuroblastoma cells expressing wild-type and mutant UBE4B. Results Low UBE4B gene expression is associated with poor outcomes in patients with neuroblastoma. UBE4B overexpression reduced neuroblastoma tumor cell proliferation, and UBE4B expression was inversely related to EGFR expression in patient tumor samples. EGFR degradation rates correlated with cellular UBE4B levels. Enhanced expression of catalytically active UBE4B resulted in reduced sensitivity to EGFR inhibition. Conclusions We have demonstrated associations between UBE4B expression and neuroblastoma patient outcomes and between UBE4B and EGFR expression in neuroblastoma tumor samples. Moreover, levels of UBE4B influenced neuroblastoma tumor cell proliferation, EGFR degradation, and response to EGFR inhibition. These results suggest UBE4B-mediated GFR trafficking may contribute to the poor prognosis of neuroblastoma tumors with 1p36 deletions, and that UBE4B expression may be a marker that can predict responses of neuroblastoma tumors to treatment.

UBE4B Protein Couples Ubiquitination and Sorting Machineries to Enable Epidermal Growth Factor Receptor (EGFR) Degradation

“…This sustained signaling is not necessarily an effect of the undegraded EGFR residing on the plasma membrane because the contribution of actively signaling and endosomally localized EGFRs is sufficient to activate initiate signal transduction cascades that mediate cell survival (44). These data suggest that UBE4B can regulate global cellular events, like proliferation and signaling, and identify UBE4B as a potential therapeutic target for cancer therapies because its mutation or deletion from cells may underlie enhanced signaling that may be pathogenic (43,45).…”

“…5C. When incubation with UBE4B was followed by incubation with USP8, ubiquitinated EGFR was not detected (lane 5 physiological relevance of the correlation of UBE4B levels with EGFR degradation may be related to differences in cellular UBE4B levels (and, therefore, EGFR levels and downstream signaling) that could underlie disease states such as cancer (43). In this regard, UBE4B-depleted cells displayed prolonged ERK1/2 activation compared with control cells following EGFR stimulation.…”

miRNA-95 Mediates Radioresistance in Tumors by Targeting the Sphingolipid Phosphatase SGPP1

“…This strategy identified 28 overlapping targets, of which four overlapping candidate gene targets (DICER1, UBE4B, SGPP1, and PTPN21) were further analyzed based upon their potential involvement in radiation resistance or oncogenic processes (11,(25)(26)(27)(28). Using qRT-PCR, we verified that their expression were significantly decreased in PC3-miR-95 cells relative to PC3-control cells (Fig.…”

Nifurtimox reduces N-Myc expression and aerobic glycolysis in neuroblastoma

“…1,2 Classification as high-risk or non-high-risk neuroblastoma depends on the stage defined by the International Neuroblastoma Staging System (INSS) 3,4 or less common the International Neuroblastoma Pathology Classification (INPC) proposed by Shimada et al 5,6 Over the past decades a multitude of prognosis and risk factors such as genetic mutations (e.g., deletion of chromosome 1p36, [7][8][9] altered expression of ALK, 10 PHOX2B) epigenetics, 9,11 ploidy 12 and age 13 have been identified. In the mid-1980s, the clinical and prognostic role of the proto-oncogene MYCN encoding for the protein N-Myc (v-myc myelocytomatosis viral related oncogene, neuroblastoma derived (avian)) was first described.…”