PDGFRalpha gene mutation and protein expression in gastrointestinal stromal tumors.

ABSTRACT

OBJECTIVE: Mutation of the PDGFRalpha is a potential candidate in the pathogenesis of KIT wild-type gastrointestinal tumors (GISTs). In this study, we evaluated the prevalence of PDGFRalpha 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 PDGFRalpha were amplified and sequenced. Immunohistochemical staining was performed in 179 patients. RESULTS: Mutations in the PDGFRalpha were detected in 6 (3.1%) patients, and were observed solely in KIT wild-type GISTs. Among the 6 patients with PDGFRalpha gene mutations, 5 patients with localized GISTs showed no relapse after resection during the 19- to 80-month follow-up period. Intensity of PDGFRalpha 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 PDGFRalpha expression showed no correlation with relapse-free survival. CONCLUSION: PDGFRalpha mutations in GISTs were found to be rare in this Korean population. Although localized GISTs with PDGFRalpha mutations showed relatively good prognosis after resection, the difference was not statistically significant.