KCTD2, an adaptor of Cullin3 E3 ubiquitin ligase, suppresses gliomagenesis by destabilizing c-Myc

Eun Jung Kim, Sung Hak Kim, Xiong Jin, Xun Jin, Hyunggee Kim

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)

Abstract

Cullin3 E3 ubiquitin ligase ubiquitinates a wide range of substrates through substrate-specific adaptors Bric-a-brac, Tramtrack, and Broad complex (BTB) domain proteins. These E3 ubiquitin ligase complexes are involved in diverse cellular functions. Our recent study demonstrated that decreased Cullin3 expression induces glioma initiation and correlates with poor prognosis of patients with malignant glioma. However, the substrate recognition mechanism associated with tumorigenesis is not completely understood. Through yeast two-hybrid screening, we identified potassium channel tetramerization domain-containing 2 (KCTD2) as a BTB domain protein that binds to Cullin3. The interaction of Cullin3 and KCTD2 was verified using immunoprecipitation and immunofluorescence. Of interest, KCTD2 expression was markedly decreased in patient-derived glioma stem cells (GSCs) compared with non-stem glioma cells. Depletion of KCTD2 using a KCTD2-specific short-hairpin RNA in U87MG glioma cells and primary Ink4a/Arf-deficient murine astrocytes markedly increased self-renewal activity in addition with an increased expression of stem cell markers, and mouse in vivo intracranial tumor growth. As an underlying mechanism for these KCTD2-mediated phenotypic changes, we demonstrated that KCTD2 interacts with c-Myc, which is a key stem cell factor, and causes c-Myc protein degradation by ubiquitination. As a result, KCTD2 depletion acquires GSC features and affects aerobic glycolysis via expression changes in glycolysis-associated genes through c-Myc protein regulation. Of clinical significance was our finding that patients having a profile of KCTD2 mRNA-low and c-Myc gene signature-high, but not KCTD2 mRNA-low and c-Myc mRNA-high, are strongly associated with poor prognosis. This study describes a novel regulatory mode of c-Myc protein in malignant gliomas and provides a potential framework for glioma therapy by targeting c-Myc function.

Original languageEnglish
Pages (from-to)649-659
Number of pages11
JournalCell Death and Differentiation
Volume24
Issue number4
DOIs
Publication statusPublished - 2017 Apr 1

Bibliographical note

Funding Information:
We thank all members of Cell Growth Regulation Lab for their helpful discussions and technical assistances. This work was supported by grants from the National Research Foundation (NRF) funded by the Ministry of Science, ICT and Future Planning (2011-0017544, 2015R1A5A1009024 and 2016R1D1A1B03931941), from Next-Generation Biogreen21 Program (PJ01107701), from the General Program of the National Natural Science Foundation of China (no. 81572891), and from Korea University.

Publisher Copyright:
© 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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