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Dizdar L, Werner TA, Drusenheimer JC, Möhlendick B, Raba K, Boeck I, Anlauf M, Schott M, Göring W, Esposito I, Stoecklein NH, Knoefel WT, Krieg A. BRAF V600E mutation: A promising target in colorectal neuroendocrine carcinoma. Int J Cancer 2018; 144:1379-1390. [PMID: 30144031 DOI: 10.1002/ijc.31828] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 07/04/2018] [Accepted: 08/02/2018] [Indexed: 12/16/2022]
Abstract
To determine the role of BRAFV600E mutation and MAPK signaling as well as the effects of BRAF and MEK directed therapy in gastroenteropancreatic neuroendocrine neoplasia (GEP-NEN), with a focus on highly aggressive gastroenteropancreatic neuroendocrine carcinoma (GEP-NEC). Using Sanger sequencing of BRAF exon 15 we determined the frequency of BRAFV600E mutations in 71 primary GEP-NENs. MEK phosphorylation was examined by immunohistochemistry in corresponding tissue samples. To evaluate the biological relevance of BRAFV600E mutation and MAPK signaling in GEP-NECs, effects of a pharmacological BRAF and MEK inhibition were analyzed in NEC cell lines both in vitro and in vivo. BRAFV600E mutation was detected in 9.9% of all GEP-NENs. Interestingly, only NECs of the colon harbored BRAFV600E mutations, leading to a mutation frequency of 46.7% in this subgroup of patients. In addition, a BRAFV600E mutation was significantly associated with high levels of MEK phosphorylation (pMEK) and advanced tumor stages. Pharmacological inhibition of BRAF and MEK abrogated NEC cell growth, inducing G1 cell cycle arrest and apoptosis only in BRAFV600E mutated cells. BRAF inhibitor dabrafenib and MEK inhibitor trametinib prevented growth of BRAFV600E positive NEC xenografts. High frequencies of BRAFV600E mutation and elevated expression levels of pMEK were detected in biologically aggressive and highly proliferative colorectal NECs. We provide evidence that targeting BRAF oncogene may represent a therapeutic strategy for patients with BRAF mutant colorectal NECs.
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Affiliation(s)
- Levent Dizdar
- Department of Surgery (A), Medical Faculty, Heinrich-Heine-University and University Hospital Duesseldorf, Duesseldorf, Germany
| | - Thomas A Werner
- Department of Surgery (A), Medical Faculty, Heinrich-Heine-University and University Hospital Duesseldorf, Duesseldorf, Germany
| | - Jasmin C Drusenheimer
- Institute of Pathology, Medical Faculty, Heinrich-Heine-University and University Hospital Duesseldorf, Duesseldorf, Germany
| | - Birte Möhlendick
- Department of Surgery (A), Medical Faculty, Heinrich-Heine-University and University Hospital Duesseldorf, Duesseldorf, Germany
| | - Katharina Raba
- Institute for Transplantation Diagnostics and Cell Therapeutics, Medical Faculty, Heinrich-Heine-University and University Hospital Duesseldorf, Duesseldorf, Germany
| | - Inga Boeck
- Institute of Pathology and Cytology, St. Vincenz Hospital Limburg, Limburg, Germany
| | - Martin Anlauf
- Institute of Pathology and Cytology, St. Vincenz Hospital Limburg, Limburg, Germany
| | - Matthias Schott
- Division for Specific Endocrinology, Medical Faculty, Heinrich-Heine-University and University Hospital Duesseldorf, Duesseldorf, Germany
| | - Wolfgang Göring
- Institute of Pathology, Medical Faculty, Heinrich-Heine-University and University Hospital Duesseldorf, Duesseldorf, Germany
| | - Irene Esposito
- Institute of Pathology, Medical Faculty, Heinrich-Heine-University and University Hospital Duesseldorf, Duesseldorf, Germany
| | - Nikolas H Stoecklein
- Department of Surgery (A), Medical Faculty, Heinrich-Heine-University and University Hospital Duesseldorf, Duesseldorf, Germany
| | - Wolfram T Knoefel
- Department of Surgery (A), Medical Faculty, Heinrich-Heine-University and University Hospital Duesseldorf, Duesseldorf, Germany
| | - Andreas Krieg
- Department of Surgery (A), Medical Faculty, Heinrich-Heine-University and University Hospital Duesseldorf, Duesseldorf, Germany
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