Neurofibromatosis type 1-related gastrointestinal stromal tumors: A special reference to loss of heterozygosity at 14q and 22q

Hidetaka Yamamoto, Taro Tobo, Mari Nakamori, Masakazu Imamura, Aya Kojima, Yoshinao Oda, Norimoto Nakamura, Tomonari Takahira, Takashi Yao, Masazumi Tsuneyoshi

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Abstract

Purpose: Multiple gastrointestinal stromal tumors (GISTs) rarely occur in patients with neurofibromatosis type 1 (NF-1). In contrast to sporadic GISTs characterized by frequent allelic losses of 1p, 14q and 22q and mutations of KIT or PDGFRA gene with the activation of the downstream RAS-MAPK pathway, the molecular pathogenetic mechanisms of NF-1-related GISTs (NF-1 GISTs) remain unclear. Methods: Thirty-one GISTs and two foci of Cajal cell hyperplasia (CCH) were obtained from five patients with NF-1. Phospho-MAPK p44/42 expression was examined by immunohistochemical stain. KIT and PDGFRA mutations were analyzed by PCR and direct sequencing methods. Loss of heterozygosity (LOH) was analyzed by PCR-based method with microsatellite markers on 14q and 22q. Results: Immunohistochemical expression of phospho-MAPK p44/42 was frequently found in NF-1 GISTs (23/25 cases, 92%). Neither the KIT nor PDGFRA mutation was detected in 25 NF-1 GISTs and 2 CCH. Among the informative cases, LOH was seen at 14q and 22q in 7/8 (87.5%) and 5/12 (41.7%) NF-1 GISTs, respectively. Such LOH was not detected in CCH, whereas it was detected in small GIST less than 1 cm in diameter. Conclusions: Our results support that KIT and PDGFRA mutations are very rare events in NF-1 GIST. Rather, activation of the Ras-MAPK pathway associated with the inactivation of the NF1 gene may play an important role in the cell proliferation of NF-1 GIST. Additionally, LOH at 14q and 22q may contribute to the relatively early phase of tumor development of NF-1 GIST.

Original languageEnglish
Pages (from-to)791-798
Number of pages8
JournalJournal of Cancer Research and Clinical Oncology
Volume135
Issue number6
DOIs
Publication statusPublished - Jun 1 2009

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All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research

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