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Oncogene. 2019 Aug 12. doi: 10.1038/s41388-019-0938-8. [Epub ahead of print]

Proteomics identifies neddylation as a potential therapy target in small intestinal neuroendocrine tumors.

Author information

1
Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden.
2
Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden.
3
Department of Pathology and Cytology, Karolinska University Hospital Solna, Stockholm, Sweden.
4
SciLifeLab, Stockholm, Sweden.
5
Department of Pharmacology, Cambridge University, Cambridge, UK.
6
Department of Clinical Genetics, Linköping University Hospital, Linköping, Sweden.
7
Uppsala Clinical Research Center, Uppsala University, Uppsala, Sweden.
8
Department of Breast, Endocrine Tumours and Sarcoma, Karolinska University Hospital Solna, Stockholm, Sweden.
9
Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden. catharina.larsson@ki.se.
10
Department of Oncology-Pathology, Karolinska Institutet, Stockholm, Sweden. lukas.orre@ki.se.
11
SciLifeLab, Stockholm, Sweden. lukas.orre@ki.se.

Abstract

Patients with small intestinal neuroendocrine tumors (SI-NETs) frequently develop spread disease; however, the underlying molecular mechanisms of disease progression are not known and effective preventive treatment strategies are lacking. Here, protein expression profiling was performed by HiRIEF-LC-MS in 14 primary SI-NETs from patients with and without liver metastases detected at the time of surgery and initial treatment. Among differentially expressed proteins, overexpression of the ubiquitin-like protein NEDD8 was identified in samples from patients with liver metastasis. Further, NEDD8 correlation analysis indicated co-expression with RBX1, a key component in cullin-RING ubiquitin ligases (CRLs). In vitro inhibition of neddylation with the therapeutic agent pevonedistat (MLN4924) resulted in a dramatic decrease of proliferation in SI-NET cell lines. Subsequent mass spectrometry-based proteomics analysis of pevonedistat effects and effects of the proteasome inhibitor bortezomib revealed stabilization of multiple targets of CRLs including p27, an established tumor suppressor in SI-NET. Silencing of NEDD8 and RBX1 using siRNA resulted in a stabilization of p27, suggesting that the cellular levels of NEDD8 and RBX1 affect CRL activity. Inhibition of CRL activity, by either NEDD8/RBX1 silencing or pevonedistat treatment of cells resulted in induction of apoptosis that could be partially rescued by siRNA-based silencing of p27. Differential expression of both p27 and NEDD8 was confirmed in a second cohort of SI-NET using immunohistochemistry. Collectively, these findings suggest a role for CRLs and the ubiquitin proteasome system in suppression of p27 in SI-NET, and inhibition of neddylation as a putative therapeutic strategy in SI-NET.

PMID:
31406256
DOI:
10.1038/s41388-019-0938-8

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