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Insulin-like growth factor 1 receptor stabilizes the ETV6-NTRK3 chimeric oncoprotein by blocking its KPC1/Rnf123-mediated proteasomal degradation.

ABSTRACT: Many oncogenes, including chimeric oncoproteins, require insulin-like growth factor 1 receptor (IGF1R) for promoting cell transformation. The ETS variant 6 (ETV6)-neurotrophic receptor tyrosine kinase 3 (NTRK3) (EN) chimeric tyrosine kinase is expressed in mesenchymal, epithelial, and hematopoietic cancers and requires the IGF1R axis for transformation. However, current models of IGF1R-mediated EN activation are lacking mechanistic detail. We demonstrate here that IGF-mediated IGF1R stimulation enhances EN tyrosine phosphorylation and that blocking IGF1R activity or decreasing protein levels of the adaptor protein insulin receptor substrate 1/2 (IRS1/2) results in rapid EN degradation. This was observed both in vitro and in vivo in fibroblast and breast epithelial cell line models and in MO91, an EN-expressing human leukemia cell line. Stable isotope labeling with amino acids in cell culture (SILAC)-based MS analysis identified the E3 ligase RING-finger protein 123 (Rnf123, more commonly known as KPC1) as an EN interactor upon IGF1R/insulin receptor (INSR) inhibitor treatment. KPC1/Rnf123 ubiquitylated EN in vitro, and its overexpression decreased EN protein levels. In contrast, KPC1/Rnf123 knockdown rendered EN resistant to IGF1R inhibitor-mediated degradation. These results support a critical function for IGF1R in protecting EN from KPC1/Rnf123-mediated proteasomal degradation. Attempts to therapeutically target oncogenic chimeric tyrosine kinases have traditionally focused on blocking kinase activity to restrict downstream activation of essential signaling pathways. In this study, we demonstrate that IGF1R inhibition results in rapid ubiquitylation and degradation of the EN oncoprotein through a proteasome-dependent mechanism that is reversible, highlighting a potential strategy for targeting chimeric tyrosine kinases in cancer.

SUBMITTER: Tognon CE

PROVIDER: S-EPMC6093223 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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Insulin-like growth factor 1 receptor stabilizes the ETV6-NTRK3 chimeric oncoprotein by blocking its KPC1/Rnf123-mediated proteasomal degradation.

Tognon Cristina E CE Rafn Bo B Cetinbas Naniye Malli NM Kamura Takumi T Trigo Genny G Rotblat Barak B Okumura Fumihiko F Matsumoto Masaki M Chow Christine C Davare Monika M Pollak Michael M Mayor Thibault T Sorensen Poul H PH

The Journal of biological chemistry 20180614 32

Many oncogenes, including chimeric oncoproteins, require insulin-like growth factor 1 receptor (IGF1R) for promoting cell transformation. The ETS variant 6 (ETV6)-neurotrophic receptor tyrosine kinase 3 (NTRK3) (EN) chimeric tyrosine kinase is expressed in mesenchymal, epithelial, and hematopoietic cancers and requires the IGF1R axis for transformation. However, current models of IGF1R-mediated EN activation are lacking mechanistic detail. We demonstrate here that IGF-mediated IGF1R stimulation ...[more]

PMID: 29903916

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Project description:Epstein-Barr virus (EBV) nuclear oncoprotein EBNA3C is essential for B-cell transformation and development of several B-cell lymphomas particularly those are generated in an immuno-compromised background. EBNA3C recruits ubiquitin-proteasome machinery for deregulating multiple cellular oncoproteins and tumor suppressor proteins. Although EBNA3C is found to be ubiquitinated at its N-terminal region and interacts with 20S proteasome, the viral protein is surprisingly stable in growing B-lymphocytes. EBNA3C can also circumvent autophagy-lysosomal mediated protein degradation and subsequent antigen presentation for T-cell recognition. Recently, we have shown that EBNA3C enhances autophagy, which serve as a prerequisite for B-cell survival particularly under growth deprivation conditions. We now demonstrate that proteasomal inhibition by MG132 induces EBNA3C degradation both in EBV transformed B-lymphocytes and ectopic-expression systems. Interestingly, MG132 treatment promotes degradation of two EBNA3 family oncoproteins-EBNA3A and EBNA3C, but not the viral tumor suppressor protein EBNA3B. EBNA3C degradation induced by proteasomal inhibition is partially blocked when autophagy-lysosomal pathway is inhibited. In response to proteasomal inhibition, EBNA3C is predominantly K63-linked polyubiquitinated, colocalized with the autophagy-lysosomal fraction in the cytoplasm and participated within p62-LC3B complex, which facilitates autophagy-mediated degradation. We further show that the degradation signal is present at the first 50 residues of the N-terminal region of EBNA3C. Proteasomal inhibition reduces the colony formation ability of this important viral oncoprotein, induces apoptotic cell death and increases transcriptional activation of both latent and lytic gene expression which further promotes viral reactivation from EBV transformed B-lymphocytes. Altogether, this study offers rationale to use proteasome inhibitors as potential therapeutic strategy against multiple EBV associated B-cell lymphomas, where EBNA3C is expressed.

Dataset Information

Insulin-like growth factor 1 receptor stabilizes the ETV6-NTRK3 chimeric oncoprotein by blocking its KPC1/Rnf123-mediated proteasomal degradation.

Publications

Insulin-like growth factor 1 receptor stabilizes the ETV6-NTRK3 chimeric oncoprotein by blocking its KPC1/Rnf123-mediated proteasomal degradation.

Similar Datasets

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