PDGFRα Gene Mutation and Protein Expression in Gastrointestinal Stromal Tumors

Abstract

Objective: Mutation of the PDGFRα is a potential candidate in the pathogenesis of KIT wild-type gastrointestinal tumors (GISTs). In this study, we evaluated the prevalence of PDGFRα mutations and corresponding protein expression in GISTs, to determine their usefulness in obtaining a prognosis. Methods: Genomic DNA was extracted from paraffin-embedded tumor tissues from 194 GISTs. Exons 12, 14 and 18 of the PDGFRα were amplified and sequenced. Immunohistochemical staining was performed in 179 patients. Results: Mutations in the PDGFRα were detected in 6 (3.1%) patients, and were observed solely in KIT wild-type GISTs. Among the 6 patients with PDGFRα gene mutations, 5 patients with localized GISTs showed no relapse after resection during the 19- to 80-month follow-up period. Intensity of PDGFRα expression was classified as 0 in 26 (14.5%), 1+ in 69 (38.5%), 2+ in 71 (39.7%) and 3+ in 13 (7.3%) patients. Levels of PDGFRα expression showed no correlation with relapse-free survival. Conclusion:PDGFRα mutations in GISTs were found to be rare in this Korean population. Although localized GISTs with PDGFRα mutations showed relatively good prognosis after resection, the difference was not statistically significant.