磷酸化血小板源生长因子受体α和C—kit在胃肠道和胃肠道外间质瘤的表达及其临床意义

目的探讨磷酸化血小板源生长因子受体α（P—PDGFR—α）在胃肠道间质瘤（GIST）和胃肠道外GIST（EGIST）的表达及临床意义，为进一步提高GIST和EGIST的病理诊断、病理分型及临床治疗提供依据。方法用免疫组织化学方法检测28例CD117阳性和13例CD117阴性的GIST和EGIST间质瘤组织中P—PDGFR-α的表达，并且用PCR直接测序的方法检测41例GISTC—kiI基因外显子9、11、13、17和P—PDGFR-α外显子12、18突变。结果P—PDGFR-α在CD117阴性的GIST表达（69．2％）显著高于在CD117阳性的GIST表达（7．1％）（P〈0．05）；P—PDGFR-α在上皮型GIST的表达（27．3％）和混合型GIST的表达（63．3％）均显著高于在梭型细胞型GIST的表达（9％）（P〈0．05）；CD117在梭型细胞型GIST的表达（53．6％）明显高于在上皮型GIST（7．1％）和混合型GIST（39．3％）的表达（P〈0．05）。在28例CD117阳性GIST中，19例有c—kit基因的突变，其中15例在外显子11有突变，4例在外显子13有突变，13例CD117阴性GIST中无C—kit基因突变：11例PDGFR-α阳性的GIST中4例有PDGFR-α基因的突变．均发生在外显子18。结论P—PDGFR-α为CD117阴性GIST的病理诊断、病理分型和临床治疗进一步提供了可靠的依据。PDGFR-α基因突变后引起产物蛋白的磷酸化可能是CD117阴性的GIST发生的重要分子基础和生物学行为。

Expression and gene mutation of phospho-platelet derived growth factor receptor alpha and C-kit in gastrointestinal and extra-gastrointestinal stromal tumors

OBJECTIVE: To investigate the expression of phospho-platelet derived growth factor receptor alpha (P-PDGFR-alpha) in gastrointestinal stromal tumors (GIST) and extra-gastrointestinal stromal tumors (EGIST) and its clinical significance. METHODS: Expression of P-PDGFR-alpha in 28 samples of positive CD117 and 13 samples of negative CD117 was detected by Envision immunohistochemical staining. Direct PCR sequencing was used to investigate the mutation status of c-kit gene exons 9, 11, 13, 17 and PDGFR-alpha gene exons 12 and 18. RESULTS: The positive rate of P-PDGFR-alpha expression in GISTs with negative CD117 was 69.2%, which was significantly higher than that in GISTs with positive CD117 (7.1%, P<0.05). The positive rates of P-PDGFR-alpha expression in epithelioid GISTs(27.3%) and mixed GIST(63.3%) were both significantly higher than that in fusiform GISTs (9%, P<0.05). The positive rate of CD117 expression in fusiform GISTs (53.6%)was significantly higher than that in epithelioid GISTs (7.1%) and mixed GISTs(39.3%, P<0.05). C-kit gene mutation was found in 19 GIST cases with positive CD117. C-kit gene mutation was found in 19 of 28 GIST patients with positive CD117, among them, mutation of exon 11 occurred in 15 cases and exon 13 in 4 cases. No C-kit gene mutation was seen in 13 GIST patients with negative CD117. PDGFR-alpha gene mutation was found in 4 of 11 GIST cases with positive P-PDGFR-alpha and all occurred in exon 18. CONCLUSIONS: Examination of P-PDGFR-alpha expression may provide reliable evidence for the further improvement of pathological diagnosis,pathological typing and treatment for GISTs with negative CD117. Phosphorylated protein induced by PDGFR-alpha mutation may be associated with the important alternative molecular mechanism and the biological behavior of GIST development.