胃肠道间质瘤c-KIT,PDGFRA基因突变及CD117,DOG-1蛋白的表达情况

c-KIT and PDGFRA mutations and expression of CD117 and DOG-1 in gastrointestinal stromal tumors

目的:回顾性研究分析133例胃肠道间质瘤(gastrointestinal stromal tumor,GIST)患者中c-KIT及PDGFRA基因突变情况及其中94例的CD117,DOG-1蛋白表达情况。方法:用下一代测序(next generation sequencing,NGS)及免疫组织化学方法分别检测以甲醛固定石蜡包埋的标本中c-KIT,PDGFRA基因突变及CD117,DOG-1蛋白表达情况,探讨不同基因突变形式与病变原发部位的相关性,并分析基因突变与蛋白表达之间的相关性。结果:133例GIST患者中男74例,女59例,发病年龄以40岁以上为主。原发于胃的57例,小肠59例,腹腔8例,直肠5例,肠系膜2例,盆腔2例。97例(72.9%)检测到c-KIT突变,其中79例(59.4%)存在11号外显子突变,13例(9.8%)9号外显子突变,4例(3.0%)13号外显子突变,5例(3.8%)17号外显子突变,全为双突变。9号外显子插入突变主要见于小肠;11号外显子W557_K558缺失突变主要见于胃。11例(8.3%)检测到PDGFRA突变,其中8例(6.0%)为18号外显子突变,3例(2.3%)为12号外显子突变。PDGFRA突变病例均为胃原发。94例GIST患者中,89例(94.7%)CD117阳性,92例(97.9%)DOG-1阳性;双阳性表达88例(74例c-KIT突变,4例PDGFRA突变),CD117单独阳性1例(野生型),DOG-1单独阳性4例(1例c-KIT突变,3例PDGFRA突变),双阴性1例(c-KIT突变)。CD117与DOG-1蛋白表达之间呈显著相关,差异有统计学意义(P<0.01)。结论:GIST中c-KIT,PDGFRA基因突变率高。c-KIT及PDGFRA基因突变形式与GIST原发部位有关。绝大多数GIST病例CD117与DOG-1双表达,CD117与DOG-1双阴性及CD117单阳性GIST病例均十分罕见,DOG-1单阳性表达病例主要见于PDGFRA突变。对于单阳性及双阴性病例的确诊,依赖于基因检测。

Objective： To analyze the mutation patterns of c-KIT and PDGFRA in 133 gastrointestinal stromal tumor（GIST） cases and expression of CD117 and DOG-1 in 94 GIST cases. Methods： Next generation sequencing（NGS） and immunohistochemistry（IHC） were used to analyze gene mutations and protein expression in formalin-fixed paraffin-embedded slides and to investigate the association between gene mutation and primary locations. Results： Among 133 GIST cases, 74 were males and 59 were females with the majority over 40 years old. There were 57 cases in the stomach, 59 in the small intestine, 8 in the abdominal cavity, 5 in the rectum, 2 in the mesenterium, and 2 in the pelvic cavity. Overall, c-KIT mutations were identified in 97 cases（72.9%）： 79 of them were involved with exon 11（59.4%）, 13 with exon 9（9.8%）, 4 with exon 13（3.0%）, and 5 with exon 17（3.8%）, including 5 cases（3.8%） presented with double mutations. Exon 9 insertion was mainly identified in small intestine, whereas deletion of W557_K558 of exon 11 was common in stomach. Mutation of PDGFRA was present in 11 cases（8.3%）, with 8 of them in exon 18（6.0%）, 3 in exon 12（2.3%）. All PDGFRA-mutated cases were derived from stomach. We also investigated the expression of CD117 and DOG-1 in 94 cases： 89（94.7%） were CD117（＋）, 92（97.9%） were DOG-1（＋）. A total of 88 cases were double positive（74 harboring c-KIT mutation and 4 harboring PDGFRA mutation）, 1 case was CD117 single positive（wild-type）, 4 cases were DOG-1 single positive（1 c-KIT mutated and 3 PDGFRA mutated）, and 1 case was double negative（c-KIT mutated）. There was significant correlation between the expression of CD117 and DOG-1（P〈0.01）. Conclusion： The mutation rate of c-KIT and PDGFRA in GIST were high. There were relations between mutation form and primary location of GIST. Most GIST cases showed CD117 and DOG-1 double positive pattern, whereas double negative and CD117 single positive were rare. DOG-1 single positive cases were mainly found in PDGFRA-mutated cases. Gene analysis is essential for diagnosis of GIST in single positive and double negative cases.