Gastroenterology

Gastroenterology

Volume 115, Issue 5, November 1998, Pages 1090-1095
Gastroenterology

Alimentary Tract
A novel gain-of-function mutation of c-kit gene in gastrointestinal stromal tumors,☆☆

https://doi.org/10.1016/S0016-5085(98)70079-4Get rights and content

Abstract

Background & Aims: The c-kit gene encodes a receptor tyrosine kinase (KIT). Recently, we found gain-of-function mutations of the c-kit gene in gastrointestinal stromal tumors (GISTs). All mutations were confined within the 11 amino acids (Lys-550 to Val-560) in the juxtamembrane domain, but one GIST showed a novel deletion-type mutation at codon 579 (Asp) in the juxtamembrane domain. The aim of this study was to clarify whether the mutation is activating. Methods: Mutant c-kit cDNA was transfected into an interleukin 3 (IL-3)-dependent Ba/F3 murine lymphoid cell line, and the magnitude of autophosphorylation of the mutant KIT was examined with or without stem cell factor (SCF), a ligand of KIT. An in vitro kinase assay was also performed. The biological behavior of the transfectant was estimated by both an in vitro proliferation assay and in vivo transplantation to nude mice. Results: The mutant KIT exhibited constitutive phosphorylation and strong kinase activity without SCF. The transfectant grew autonomously without IL-3 and SCF, and it formed tumors in nude mice. Conclusions: Deletion at codon 579 (Asp) in the juxtamembrane domain of the c-kit gene is a novel gain-of-function mutation other than the region between Lys-550 and Val-560.

GASTROENTEROLOGY 1998;115:1090-1095

Section snippets

Materials

A mesenchymal stomach tumor, obtained during a surgical procedure, was used for the examination. Normal gastric tissue near the tumor was used as a control.

Immunohistochemistry

A rabbit polyclonal antibody against the human KIT was purchased from IBL Co. (Fujioka, Japan). A rabbit polyclonal antibody against human S-100 protein and mouse monoclonal antibodies against human α–smooth muscle actin, vimentin, and desmin were purchased from DAKO (Glostrup, Denmark). A mouse monoclonal antibody against human CD34 antigen

Results

Immunohistochemistry was performed to show that the tumor was in fact a GIST. All tumor cells were positive for both KIT and CD34, which are the most reliable markers for GISTs (Figure 1AC).

. Immunohistochemical characteristics of the tumor. Stained with (A) H&E, (B) anti-KIT antibody, (C) anti-CD34 antibody, (D) antidesmin antibody, (E) anti–α-smooth muscle actin antibody, (F) anti-S100 antibody, and (G) antivimentin antibody. The tumor was positive for KIT, CD34, and vimentin and negative for

Discussion

Recently we found gain-of-function mutations of the c-kit gene in 5 of 6 GISTs examined.14 All mutations were located within the 11 amino acids (Lys-550 to Val-560) of the juxtamembrane domain.14 In the process of further investigation on whether gain-of-function mutations in GISTs were restricted in the above mentioned site, we found a novel deletion-type mutation at a codon 579 (Asp) in the juxtamembrane domain. In the present study, we show that the novel mutation also resulted in

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  • Cited by (0)

    Address requests for reprints to: Koji Isozaki, M.D., Ph.D., Second Department of Internal Medicine, Osaka University Medical School, Yamadaoka 2-2, Suita, Osaka 565-0871, Japan. Fax: (81) 6-879-3739.

    ☆☆

    Supported by grants from the Ministry of Education, Science, Culture and Sports of Japan.

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