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Gain-of-Function Mutations of Receptor Tyrosine Kinases in Gastrointestinal Stromal Tumors

[ Vol. 7 , Issue. 8 ]

Author(s):

K. Isozaki and S. Hirota   Pages 469 - 475 ( 7 )

Abstract:


Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in human gastrointestinal tract. We first found that most GISTs expressed KIT, a receptor tyrosine kinase encoded by protooncogene c-kit and that approximately 90% of the sporadic GISTs had somatic gain-of-function mutations of the c-kit gene. Since both GISTs and interstitial cells of Cajal (ICCs) were double-positive for KIT and CD34, GISTs were considered to originate from ICCs or their precursor cells. We also found that germline gain-of-function mutations of the c-kit gene resulted in familial and multiple GISTs with diffuse hyperplasia of ICCs as the preexisting lesion. Moreover, we found that about half of the sporadic GISTs without c-kit gene mutations had gain-of-function mutations of platelet-derived growth factor receptor alpha (PDGFRA) gene that encodes another receptor tyrosine kinase. Imatinib which is known to inhibit constitutively activated BCR-ABL tyrosine kinase in chronic myelogenous leukemia also inhibits constitutive activation of mutated KIT and PDGFRA, and is now being used for metastatic or unresectable GISTs as a molecular target drug. Mutational analyses of c-kit and PDGFRA genes are considered to be significant for prediction of effectiveness of imatinib and newly developed/ developing other agents on GISTs. Some mouse models of familial and multiple GISTs have been genetically created, and may be useful for further investigation of GIST biology.

Keywords:

Gastrointestinal stromal tumors, gain-of-function mutation, c-kit gene, PDGFRA gene, molecular target therapy

Affiliation:

Department of Surgical Pathology,Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya,Hyogo 663-8501, Japan.



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