Novel germline mutation of KIT associated with familial gastrointestinal stromal tumors and mastocytosis

Gastrointestinal stromal tumors (GISTs) are often associated with activating KIT mutations, affecting regulatory domains of the KIT tyrosine kinase. Sporadic mastocytosis in adults is usually also caused by KIT mutations that, however, activate KIT by affecting the intracellular enzymatic site of the molecule. Most GISTs respond to KIT inhibitors that bind to the enzymatic site; in most cases of mastocytosis, however, the modified enzymatic site is not affected by these drugs. We present a kindred with both familial GISTs and mastocytosis that express a novel germline KIT mutation in exon 8, resulting in deletion of codon 419 and affecting the extracellular domain of KIT. This mutation activates KIT, and the mutant KIT is inhibited by the tyrosine kinase inhibitor imatinib mesylate. Our studies identify a new regulatory region in the KIT molecule and strongly suggest that patients with extracellular KIT mutations respond to tyrosine kinase inhibitors.     

Endosonographic diagnosis of recurrent gastrointestinal stromal tumors associated with Carney's syndrome

This is a report of a patient who manifests all of the features of Carney's syndrome, including gastrointestinal stromal tumors (GISTs), extra-adrenal paragangliomas, and pulmonary chondromas. The patient underwent surgical resection of a gastric GIST; a retroperitoneal, nonfunctional paraganglioma; and a mediastinal, catecholamine-secreting paraganglioma (pheochromocytoma). Recently, new gastric GISTs were diagnosed by endoscopic, ultrasound-guided, fine-needle aspiration (EUS-FNA) biopsy and were resected. Recurrence of stromal tumors following complete resection is common in Carney's syndrome and presents considerable management challenges. This case illustrates several important points: (1) Carney's syndrome, although rare, should be considered in patients with foregut GISTs; (2) GISTs associated with Carney's syndrome, like sporadic gastric GISTs, may have a more indolent clinical course; and (3) EUS-FNA may be useful for the diagnosis and management of GISTs in this syndrome.     

Familial gastrointestinal stromal tumors associated with dysphagia and novel type germline mutation of KIT gene

A family with multiple gastrointestinal stromal tumors (GISTs), a new type of germline mutation of KIT gene, and dysphagia is reported. The mutation was observed at Asp-820 in tyrosine kinase (TK) II domain. Mutations in TK II domain have been found in mast cell and germ cell tumors but not in GISTs, and the present family members are the first reported cases of GISTs with TK II domain mutations, including sporadic GISTs. Because interleukin 3-dependent Ba/F3 murine lymphoid cells transfected with the mutant KIT complementary DNA grew autonomously without any growth factors and formed tumors in nude mice, the mutation was considered to be gain-of-function type. Family members with the germline KIT mutation reported dysphagia, but those without the mutation did not. The mechanism of dysphagia was examined with gastrointestinal fiberscopy, endoscopic ultrasonography, and esophageal manometry. No mechanical obstruction was found, and the esophagus was not remarkably dilated. In the family members with dysphagia, endoscopic ultrasonography at the esophagocardiac junction showed a thickened hyperechoic layer between the circular and longitudinal muscle layers, suggesting hyperplasia of interstitial cells of Cajal at the myenteric plexus layer. Manometry showed low resting lower esophageal sphincter pressure and abnormal simultaneous contractions of the esophagus without normal peristalsis. These findings indicate that the dysphagia of the present family is different from typical achalasia. This is the first report of familial dysphagia caused by germline gain-of-function mutation of the KIT gene at the TK II domain.     

Defects in succinate dehydrogenase in gastrointestinal stromal tumors lacking KIT and PDGFRA mutations

Carney-Stratakis syndrome, an inherited condition predisposing affected individuals to gastrointestinal stromal tumor (GIST) and paraganglioma, is caused by germline mutations in succinate dehydrogenase (SDH) subunits B, C, or D, leading to dysfunction of complex II of the electron transport chain. We evaluated the role of defective cellular respiration in sporadic GIST lacking mutations in KIT or PDGFRA (WT). Thirty-four patients with WT GIST without a personal or family history of paraganglioma were tested for SDH germline mutations. WT GISTs lacking demonstrable SDH genetic inactivation were evaluated for SDHB expression by immunohistochemistry and Western blotting and for complex II activity. For comparison, SDHB expression was also determined in KIT mutant and neurofibromatosis-1-associated GIST, and complex II activity was also measured in SDH-deficient paraganglioma and KIT mutant GIST; 4 of 34 patients (12%) with WT GIST without a personal or family history of paraganglioma had germline mutations in SDHB or SDHC. WT GISTs lacking somatic mutations or deletions in SDH subunits had either complete loss of or substantial reduction in SDHB protein expression, whereas most KIT mutant GISTs had strong SDHB expression. Complex II activity was substantially decreased in WT GISTs. WT GISTs, particularly those in younger patients, have defects in SDH mitochondrial complex II, and in a subset of these patients, GIST seems to arise from germline-inactivating SDH mutations. Testing for germline mutations in SDH is recommended in patients with WT GIST. These findings highlight a potential central role of SDH dysregulation in WT GIST oncogenesis.     

High frequency of SDHB germline mutations in patients with malignant catecholamine-producing paragangliomas: implications for genetic testing

CONTEXT: Adrenal and extraadrenal paragangliomas are tumors of chromaffin cells that are usually benign but that may also develop into malignant disease. Mutations of the gene for succinate dehydrogenase subunit B (SDHB) are associated with a high risk of malignancy, but establishing the precise contribution requires relatively large numbers of patients with well-defined malignancy. OBJECTIVE: We assessed the prevalence of SDHB mutations in a series of patients with malignant paraganglioma. DESIGN: SDHB mutation testing was carried out in 44 consecutive patients with malignant paraganglioma. Clinical characteristics of patients with malignant disease due to SDHB mutations were compared with those without mutations. RESULTS: Pathogenic SDHB mutations were found in 13 of the 44 patients (30%). Close to one third of patients had metastases originating from an adrenal primary tumor, compared with a little over two thirds from an extraadrenal tumor. Among the latter patients, the frequency of SDHB mutations was 48%. CONCLUSION: This study establishes that missense, nonsense, frameshift, and splice site mutations of the SDHB gene are associated with about half of all malignancies originating from extraadrenal paragangliomas. The high frequency of SDHB germline mutations among patients with malignant disease, particularly when originating from an extraadrenal paraganglioma, may justify a high priority for SDHB germline mutation testing in these patients.     

Gain-of-function mutations of platelet-derived growth factor receptor alpha gene in gastrointestinal stromal tumors

BACKGROUND & AIMS: Most gastrointestinal stromal tumors (GISTs) have gain-of-function mutations of c-kit receptor tyrosine kinase (KIT) gene, but some GISTs do not. We investigated the cause of GISTs without KIT mutations. Because GISTs apparently expressed platelet-derived growth factor receptor (PDGFR) alpha, we examined whether GISTs without KIT mutations had a mutation of PDGFR alpha. METHODS: Whole coding region of PDGFR alpha complementary DNA (cDNA) was sequenced in GISTs with or without KIT mutations. Mutant PDGFR alpha cDNA was transfected into 293T human embryonic kidney cells, and autophosphorylation of PDGFR alpha was examined. Proliferation of Ba/F3 murine lymphoid cells stably transfected with mutant PDGFR alpha cDNA was estimated by tritium thymidine incorporation. Wild-type KIT cDNA was cotransfected with mutant PDGFR alpha cDNA, and immunoprecipitation by anti-KIT antibody was performed. Inhibitory effect of Imatinib mesylate on activated PDGFR alpha was examined. RESULTS: We found 2 types of constitutively activated mutations of PDGFR alpha, Val-561 to Asp or Asp-842 to Val, in 5 of 8 GISTs without KIT mutations but not in 10 GISTs with KIT mutations. Stable transfection of each mutation induced autonomous proliferation of Ba/F3 cells. Constitutively activated mutant PDGFR alpha bound and activated the cotransfected wild-type KIT. The constitutive activation of PDGFR alpha with Val-561 to Asp was inhibited effectively by Imatinib mesylate but that of PDGFR alpha with Asp-842 to Val was inhibited only weakly, even at the concentration of 10 micromol/L. CONCLUSIONS: The gain-of-function mutations of PDGFR alpha appear to play an important role in development of GISTs without KIT mutations.     

67例胃肠道间质瘤患者的内镜诊断和治疗

目的 探讨胃肠道间质瘤的内镜下特点及内镜治疗方式.方法 回顾性分析2004年1月～2011年6月间我院67例胃肠道间质瘤患者的临床及其病理资料,统计患者的临床表现、辅助检查及治疗等.辅助检查方法包括内镜(超声内镜)或影像学检查(CT平扫及增强),治疗方法为内镜下治疗或外科手术治疗.结果 胃肠道间质瘤男女发病率相似,以中老年患者居多,45岁以上者55例(82.1％).病程长短不等,以黑便,血便(27例,40.3％)、腹痛(18例,26.9％)、腹部不适(8例,11.9％)等非特异性症状为主.病变部位位于胃(38.8％)及小肠(40.3％)者居多,结肠(13.4％)者亦不少见.内镜及超声内镜检查53例(79.1％),其中行内镜引导下细针穿刺者1例;CT平扫及增强扫描14例(20.9％).内镜下治疗45例(67.2％),外科手术治疗22例(32.8％),67例患者均治愈出院.结论 随着双气囊小肠镜的开展及普及,小肠间质瘤诊断率明显提高.超声内镜辅助下行内镜下治疗,是诊治胃肠道间质瘤的有效手段之一.     

Expression and clinical significance of SSH1 in gastrointestinal stromal tumors

<正>Objective To investigate the correlations between the expression of the slingshot-1(SSH1) and the general clinicopathological factors in gastrointestinal stromal tumor (GIST) patients. Methods Immunohistochemical staining was used to detect the expression of SSH1 protein in 96 gastrointestinal stromal tumors,and the correlations between expression level of SSH1 and general     

PDGFRA germline mutation in a family with multiple cases of gastrointestinal stromal tumor

Familial gastrointestinal stromal tumor (GIST) is a rare autosomal dominant genetic disorder associated with KIT germline mutations. In sporadic forms of the disease, somatic mutations target either KIT or PDGFRA genes. In a kindred in which 5 individuals had GIST, no germline mutation in KIT coding sequence has been detected. We hypothesized that the PDGFRA gene could be a predisposing gene in familial GIST. We sequenced PDGFRA exons 12 and 18 because several somatic mutations were identified within this region. We detected a germline PDGFRA missense mutation, 2675G > T, resulting in a tyrosine substitution for the highly conserved aspartic acid at codon 846. This mutation showed perfect cosegregation with the GIST phenotype among the 7 family members tested. Interestingly, PDGFRA Asp846 is homologous to codon 820, which is located in the KIT tyrosine kinase II domain. In a previous study, a KIT germline Asp820Tyr mutation was detected in a Japanese kindred in which 6 individuals had GIST. Transfection of a KIT820Tyr complementary DNA in nude mice was found to be tumorigenic confirming the oncogenic potential of this mutation. The present study shows that PDGFRA is a second familial GIST predisposing gene. These results indicate a further example of involvement of structurally related genes in familial cancer syndromes.     

Familial gastrointestinal stromal tumor with hyperpigmentation: association with a germline mutation of the c-kit gene

We describe 2 siblings with multiple gastrointestinal stromal tumors (GISTs) and cutaneous hyperpigmentation. Both had a point mutation of the c-kit gene. The patients were sisters who had exhibited cutaneous hyperpigmentation since their late teens, but the diagnosis of multiple gastrointestinal submucosal tumors was not made until they were 41 and 45 years old. Histologic examination showed that these tumors were GISTs expressing CD34 and Kit protein. Both patients died of GISTs. Single-strand conformation polymorphism analysis showed a mutation of c-kit in tumor DNA extracted from paraffin-embedded specimens. Direct sequencing analysis showed that the point mutation occurred at codon 559 of exon 11 (Val-->Ala). The same single-point mutation was detected in DNA extracted from peripheral leukocytes obtained from the younger sister and her 2 children (who had similar general hyperpigmentation) as well as in DNA from a skin biopsy specimen taken from the older sister. The germline mutation at codon 559 of the c-kit gene found in the present familial GISTs differed from that in a previously reported case of familial GISTs. We propose that GISTs caused by a germline mutation of the c-kit gene should be referred to as GIST-cutaneous hyperpigmentation disease.     

Rectal gastrointestinal stromal tumors:Imaging features with clinical and pathological correlation

AIM:To investigate computed tomography(CT) and magnetic resonance imaging(MRI) manifestations of rectal gastrointestinal stromal tumors(GISTs) in order to enhance the recognition of these rare tumors.METHODS:Fourteen patients with pathologically proven rectal GISTs were retrospectively reviewed.Patient histories were retrospectively reviewed for patient age,gender,presenting symptoms,endoscopic investigations,operation notes and pathologic slides.All tumors were evaluated for CD117,CD34 expression,and the tumors were stratified according to current criteria of the National Institutes of Health(NIH).In all cases the first pre-operation imaging findings(CT and MRI,n = 3;MRI only,n = 8;CT only,n = 3) were analyzed by two experienced radiologists by consensus,which include:tumor size,shape,CT density(hypodense,isodense and hyperdense),MRI signal intensity(hypointense,isointense and hyperintense),epicenter(intraluminal or extraluminal),margin(well-defined or ill-defined),internal component(presence of calcifications,necrosis,hemorrhage or ulceration),pattern and degree of enhancement,invasion into adjacent structures.After review of the radiologic studies,clinical and pathological findings were correlated with radiological findings.RESULTS:The patients,13 men and 1 woman,were aged 31-62 years(mean = 51.5 ± 10.7 years).The most common initial presentation was hematochezia(n = 6).The mean tumor diameter was 5.68 ± 2.64 cm(range 1.5-11.2 cm).Eight lesions were round or oval,and 6 lesions were irregular.Eleven lesions were welldefined and 3 had ill-defined margins.Ten tumors were extraluminal and 4 were intraluminal.The density and MR signal intensity of the solid component of the lesions were similar to that of muscle on unenhanced CT(n = 6) and T1-weighted images(n = 11),and hyperintense on T2-weighted MR images.Calcification was detected in 2 tumors.Following intravenous injection of contrast media,3 lesions had mild enhancement and 11 lesions had moderate enhancement.Enhancement was homogenous in 3 lesions and hete     

DOG1、CD117和PDGFRA在胃肠道间质瘤中的表达及相关性

目的:探讨DOG1、CD117和血小板衍生生长因子受体α(PDGFRA)在胃肠道间质瘤(GISTs)诊断中的意义,并分析与其GISTs 临床病理因素和危险度的关系.方法:应用免疫组织化学Envision二步法检测63例GISTs及43例非GISTs间叶源性肿瘤患者中DOG1、CD117及PDGFRA的表达,并分析上述免...     

Expression of Ets-1 proto-oncoprotein in gastrointestinal stromal tumors, leiomyomas and schwannomas

AIM: Gastrointestinal stromal tumors (GISTs) are rare. GISTs differ from other mesenchymal tumors of the gastrointestinal tract (e.g. leiomyomas and schwannomas). The purpose of this study was to investigate the role of Ets-1 in the growth and differentiation of GISTs. METHODS: Twenty-eight GISTs, nine leiomyomas and six schwannomas were examined by immunohistochemical staining method for Ets-1 in this study. Specimens were selected from surgical pathology archival tissues at Nagasaki University Hospital. RESULTS: Ets-1 protein was expressed in the cytoplasm of cells in all of these tumors. Immunohistochemical staining revealed that 27 GISTs (96.4%), six leiomyomas (66.7%), and five schwannomas (83.3%) were positive for Ets-1. Ets-1 expression was statistically different between GISTs and leiomyomas (P< 0.005). However, there was no correlation between Ets-1 expression and clinical risk categories. CONCLUSION: Ets-1 plays an important role in the growth and differentiation of GISTs, leiomyomas and schwannomas.     

Clinical manifestations and prognostic factors in patients with gastrointestinal stromal tumors

AIM: To investigate the incidence of CD117-positive immunohistochemical staining in previously diagnosed gastrointestinal (GI) tract stromal tumors (GIST) and to analyze the tumors‘ dinical manifestations and prognostic factors. METHODS: We retrospectively reviewed 91 cases with a previous diagnosis of GI stromal tumor, leiomyoma, or leiomyosarcoma. Tissue samples were assessed with CDl17, CD34, SMA and Sl00 immunohistochemical staining. Clinical and pathological characteristics were analyzed for prognostic factors. RESULTS: CDl17 was positive in 81 (89%) of 91 tissuesamples. There were 59 cases (72.8%) positive for CD34, 13 (16%) positive for SMA, and 12 (14.8%) positive for S100. There was no gender difference in patients with CD117-positive GIST. Their mean age was 65 years. There were 44 (54%) tumors located in the stomach and 29 (36%) in the small intestine. The most frequent presenting symptoms were abdominal pain and GI bleeding. The mean tumor size was 7.5&#177;5.7 cm. There were 35 cases (43.2%) with tumors &gt;5 cm. The tumor size correlated significantly with tumor mitotic count and resectability. Tumor size, mitotic count, and resectability correlated significantly with tumor recurrence and survival. There was recurrent disease in 39% of our patients, and their mean survival after recurrence was 16.6 months. Most recurrences were at the primary site or metastatic to the liver. Twenty-six percent of our patients died of their disease.CONCLUSION: Traditional histologic criteria are not specific enough to diagnose GIST. This diagnosis must be confirmed with CDl17 immunohistochemical staining. Prognosis is dependent on tumor size, mitotic count, and resectability.     

肿瘤-睾丸抗原MAGE-1和NY-ESO-1 mRNA在胃肠间质瘤中的表达

目的:探讨肿瘤-睾丸抗原(CTA)MAGE-1和NY-ESO-1作为胃肠间质瘤(GISTs)免疫治疗特异性靶点及MAGE-1和NY-ESO-1 mRNA作为辅助GISTs危险度分级指标的可能性.及其与GISTs生物学行为的关系.方法:采用逆转录-聚合酶链反应(RT-PCR)技术,检测30例GISTs中MAGE-1和NY-ESO-1mRNA的表达,并取正常胃肠道组织作为阴性对照组,同时分析MAGE-1和NY-ESO-1mRNA表达与病理特征的关系.结果:正常对照组中无阳性表达,30例GISTs中,18例至少表达一种CTA,MAGE-1和NY-ESO-1 mRNA在GISTs中的表达率分别为30%和47%.MAGE-1和NY-ESO-1 mRNA表达与患者年龄、性别和病理类型无关,而与肿瘤生长部位、肿瘤大小及危险度分级有关(P<0.05).MAGE-1和NY-ESO-1 mRNA在低危、中危、高危三个组中表达量随着危险度分级的升高而增高,三组间差异有统计学意义(P<0.05).MAGE-1和NY-ESO-1 mRNA在GISTs中的表达不存在相关性(r=0.018,P>0.05).结论:MAGE-1和NY-ESO-1 mRNA在GISTs中的高特异性表达,其抗原有望成为GISTs免疫治疗特异性的靶点:MAGE-1和NY-ESO-1 mRNA表达与GISTs危险度分级有关,MAGE-1和NY-ESO-1 mRNA有望成为辅助GISTs危险度分级的诊断指标.     

Frequent fusion of the JAZF1 and JJAZ1 genes in endometrial stromal tumors

Endometrial stromal tumors are divided into three types: benign stromal nodules, endometrial stromal sarcomas, and undifferentiated endometrial sarcomas. A variety of cytogenetic abnormalities involving chromosome 7 have been reported in endometrial stromal sarcomas, including a recurrent t(7;17)(p15;q21). We have identified two zinc finger genes, which we have termed JAZF1 and JJAZ1, at the sites of the 7p15 and 17q21 breakpoints. Analyses of tumor RNA indicate that a JAZF1/JJAZ1 fusion is present in all types of endometrial stromal tumors; however, the fusion appears to be rarer among endometrial stromal sarcomas that would be considered high-grade according to certain classification schemes. These findings suggest that the less malignant endometrial stromal tumors may evolve toward more malignant types, but that some endometrial stromal sarcomas with relatively abundant mitotic activity may compose a biologically distinct group.