胃肠间质瘤KIT和PDGFRA基因突变的检测和意义

目的 探讨中国胃肠间质瘤(GIST)患者KIT和血小板源性生长受体α(PDGFRA)基因突变的特点,分析其临床意义.方法 对136例GIST患者肿瘤组织进行DNA抽提、聚合酶链反应(PCR)扩增和直接测序,检测KIT基因外显子9、11、13、17和PDGFRA基因12、18外显子突变;并对8例取得伊马替尼耐药瘤组织的患者进行2次检测.结果 在136例患者中,KIT突变111例(81.6%).其中外显子11突变95例(69.8%),外显子9突变16例(11.8%),未检测到PDGFRA突变的病例.KIT和PDGFRA野生型25例(18.4%).KIT外显子11突变最常见为5'缺失突变,共60例(60/95,63.2%),其次为点突变21例(21/95,22.1%);KIT外显子9突变均为插入串联重复,其中14例(14/16,87.5%)为常见的密码子502和503重复,而另外2例为罕见的密码子501和502重复.不同性别、年龄以及晚期GIST患者和潜在恶性的GIST患者间突变情况差异无统计学意义(P＞0.05);而不同部位GIST的KIT外显子11突变发生率差异有统计学意义(P＜0.01).伊马替尼耐药GIST的检测中发现1例继发的KIT外显子17点突变(Asp820Val+Tyr823Asp).结论 KIT基因突变在中国GIST患者中常见,不同部位间KIT外显子11突变差异有统计学意义.KIT继发性突变发生于靶向药物伊马替尼耐药的患者.

Detection of KIT and PDGFRA mutations in gastrointestinal stromal tumors

Objective To investigate the mutations of KIT and PDGFRA genes and their clinical significance in Chinese patients with gastrointestinal stromal tumor (GIST). Methods Molecular analysis of KIT exons 9, 11, 13, 17 and PDGFRA exons 12, 18 was performed on 136 patients from a single institute. Specimens from imatinib-resistant tumors in 8 cases were studied to identify molecular correlations of imatinib resistance. Results KIT mutations was found in 111 patients (81.6% ) , among whom exons 11 and 9 were mutated in 95 (69.8% ) and 16 (11.8% ) patients, respectively. Wild types of KIT and PDGFRA was identified in the other 25 patients (18.4% ). Inflamed deletions in the 5 ' end were most common molecular changes in mutated exon 11 (60/95, 63.2% ), followed by point mutation (21/95, 23.1% ). Rare internal tandem duplications involving codon 501-502 of exon 9 were found in 2 cases (Ser501-Ala5O2dup, 2/16, 13.5% ). Compared to intestinal GIST, exon 11 mutation was more common in gastric and rectal GIST (P<0.01). Secondary point mutations on exon 17 of KIT were identified in an imatinib-resistant patient (Asp820Val +Tyr823Asp). Conclusion KIT mutations is common in Chinese GIST patients. Mutational status is different in varied primary tumor locations. Secondary mutations of KIT can be found in imatinib-resistant patients.