Deficiency of platelet-derived growth factor receptor-α-positive cells in Hirschsprung's disease colon

AIM: To investigate whether the expression of plateletderived growth factor receptor-α-positive(PDGFRα^+)-cells is altered in Hirschsprung's disease(HD).METHODS: HD tissue specimens(n = 10) were collected at the time of pull-through surgery, while colonic control samples were obtained at the time of colostomy closure in patients with imperforate anus(n = 10). Immunolabelling of PDGFRα^+-cells was visualized using confocal microscopy to assess the distribution of these cells, while Western blot analysis was undertaken to quantify PDGFRα protein expression.RESULTS: Confocal microscopy revealed PDGFRα+-cells within the mucosa, myenteric plexus and smooth muscle in normal controls, with a marked reduction in PDGFRα^+-cells in the HD specimens. Western blotting revealed high levels of PDGFRα protein expression in normal controls, while there was a striking decrease in PDGFRα protein expression in the HD colon.CONCLUSION: These findings suggest that the altered distribution of PDGFRα^+-cells in both the aganglionic and ganglionic HD bowel may contribute to the motility dysfunction in HD.

Expression of NG2 and platelet-derived growth facto receptor alpha in the developing neonatal rat brain

Platelet-derived growth factor receptor alpha （PDGFRct） is a marker of oligodendrocyte precursor cells in the central nervous system. NG2 is also considered a marker of oligodendrocyte precursor cells. However, whether there are differences in the distribution and morphol- ogy of oligodendrocyte precursor cells labeled by NG2 or PDGFRa in the developing neonatal rat brain remains unclear. In this study, by immunohistochemical staining, NG2 positive （NG2＋） cells were ubiquitous in the molecular layer, external pyramidal layer, internal pyramidal layer, and polymorphic layer of the cerebral cortex, and corpus callosum, external capsule, piriform cortex, and medial septal nucleus. NG2~ cells were stellate or fusiform in shape with long processes that were progressively decreased and shortened over the course of brain development. The distribution and morphology of PDGFRct positive （PDGFRa＋） cells were coincident with NG2＋ cells. The co- localization of NG2 and PDGFRu in the cell bodies and processes of some cells was confirmed by double immunofluorescence labeling. Moreover, cells double-labeled for NG2 and PDGFRa were predominantly in the early postnatal stage of development. The numbers of NG2＋/PDGFRa＋ cells and PDGFRa＋ cells decreased, but the number of NG2＋ cells increased from postnatal days 3 to 14 in the developing brain. In addition, amoeboid microglial cells of the corpus callosum, newborn brain macrophages in the normal developing brain, did not express NG2 or PDGFRu, but NG2 expression was detected in amoeboid microglia after hypoxia. The present results suggest that NG2 and PDGFRct are specific markers of oligodendrocyte precursor cells at different stages during early development. Additionally, the NG2 protein is involved in inflammatory and pathological processes of amoeboid microglial cells.

Basic fibroblast growth factor gene transfection in repair of internal carotid artery aneurysm wall

Surgery or interventional therapy has some risks in the treatment of cerebral aneurysm. We established an internal carotid artery aneurysm model by dripping elastase in the crotch of the right internal and external carotid arteries of New Zealand rabbits. Following model induction, lentivirus carrying basic fibroblast growth factor was injected through the ear vein. We found that the longer the action time of the lentivirus, the smaller the aneurysm volume. Moreover, platelet-derived growth factor expression in the aneurysm increased, but smooth muscle 22 alpha and hypertension-related gene 1 mRNA expression decreased. At 1,2, 3, and 4 weeks following model establishment, following 1 week of injection of lentivirus carrying basic fibroblast growth factor, the later the intervention time, the more severe the blood vessel damage, and the bigger the aneurysm volume, the lower the smooth muscle 22 aJpha and hypertension-related gene ~ mRNA expression. Simultaneously, platelet-derived growth factor expression decreased. These data suggest that recombinant lentivirus carrying basic fibroblast growth factor can repair damaged cells in the aneurysmal wall and inhibit aneurysm dynamic growth, and that the effect is dependent on therapeutic duration.

DOG1 is useful for diagnosis of KIT-negative gastrointestinal stromal tumor of stomach

Approximately 80%-95%of gastrointestinal stromal tumors(GISTs)show positive staining for KIT,while the other 5%-20%show negative staining.If the tumor is negative for KIT,but is positive for CD34,a histological diagnosis is possible.However,if the tumor is negative for KIT,CD34,S-100,and SMA,a definitive diagnosis is often challenging.Recently,Discovered on GIST-1(DOG1)has received considerable attention as a useful molecule for the diagnosis of GIST.DOG1,a membrane channel protein,is known to be overexpressed in GIST.Because the sensitivity and specificity of DOG1 are higher than those of KIT,positive staining for DOG1has been reported,even in KIT-negative GISTs.KITnegative GISTs most commonly arise in the stomach and are mainly characterized by epithelioid features histologically.We describe our experience with a rare case of a KIT-negative GIST of the stomach that was diagnosed by positive immunohistochemical staining for DOG1 in a patient who presented with severe anemia.Our findings suggest that immunohistochemical staining for DOG1,in addition to gene analysis,is useful for the diagnosis of KIT-negative tumors that are suspected to be GISTs.

Is exon mutation analysis needed for adjuvant treatment of gastrointestinal stromal tumor?

Gastrointestinal stromal tumors(GISTs) are the most common soft tissue sarcoma of the gastrointestinal tract,resulting from an activating mutation of stem cell factor receptor(KIT),and an activating mutation of the homologous platelet-derived growth factor receptor alpha(PDGFRA) kinase.Most GISTs(90%-95%) are KIT-positive.About 5% of GISTs are truly negative for KIT expression.GISTs have been documented to resistant conventional chemotherapeutics.Due to the KIT activation that occurs in the majority of the cases,KIT inhibition is the primary treatment approach in the adjuvant treatment of metastatic GISTs.Imatinib mesylate is an oral agent that is a selective protein tyrosine kinase inhibitor of the KIT protein tyrosine kinase,and it has demonstrated clinical benefit and objective tumor responses in most GIST patients in phase Ⅱ and Ⅲ trials.The presence and the type of KIT or PDGFRA mutation are predictive of response to imatinib therapy in patients with advanced and metastatic disease.Molecular analysis in phaseⅠ-Ⅱ trials revealed significant differences in objective response,progression-free survival,and overall survival between GISTs with different kinase mutations.The aim of this letter is to touch on the need for exon mutation analysis for adjuvant treatment with imatinib in GIST patients.

Characterizing gastrointestinal stromal tumors and evaluating neoadjuvant imatinib by sequencing of endoscopic ultrasound-biopsies

AIM To evaluate endoscopic ultrasound(EUS)-guided biopsies for the pretreatment characterization of gastrointestinal stromal tumors(GIST) to personalize the management of patients.METHODS All patients with lesions suspected to be GIST who were referred for EUS-sampling at a tertiary Swedish center were eligible for inclusion 2006-2015. During the observational study phase(2006-2011), routine fine-needle-aspiration(EUS-FNA) was performed.In 2012-2015, we converted to an interventional, randomized protocol with dual sampling EUS-FNA and fine-needle-biopsy-sampling(EUS-FNB) for all lesions. c-KIT-and DOG-1-immunostaining was attempted in all samples and a manual count of the Ki-67-index was performed. FNB-sampled tissue and the resected specimens were subjected to Sanger sequencing of the KIT and platelet-derived growth factor alpha(PDGFRA) genes. RESULTS In all, 64 unique patients with GIST were included, and of these, 38 were subjected to pretreatment dual sampling. EUS-FNB had a higher diagnostic sensitivity when compared head-to-head with EUS-FNA(98% vs 58%, P < 0.001) and was more adequate for Ki-67-indexing(Ki-67EUS)(92% vs 40%, P < 0.001). Sequencing of EUS-biopsies was successful in 43/44(98%) patients, and the mutation profiles(KIT-mutation 73%, PDGFRA-mutation 18%, wild-type 7%) were fully congruent with those detected in the corresponding resected specimens. In imatinib-na?ve patients, the Ki-67_(EUS) was comparable with the Ki-67-index in the corresponding surgical specimens(Ki-67_(SURG))(2.7% vs 2.9%, P = 0.68). In patients treated with neoadjuvant imatinib who also carried mutations indicating sensitivity, the Ki-67 EUS was higher than the Ki-67_(SURG)(2.5% vs 0.2%, P = 0.005), with a significant reduction in the Ki-67-index of-91.5%(95%CI:-82.4 to-96.0, P = 0.005). CONCLUSION EUS-guided biopsy sampling is accurate for the pretreatment diagnosis and characterization of GISTs and allows the prediction and evaluation of tumor response to neoadjuvant imatinib therapy.

Progress in the treatment of gastrointestinal stromal tumors

Gastrointestinal stromal tumor(GIST)is a type of tumor that originates from the mesenchymal tissue of the digestive tract and accounts for most interstitial tumors of the gastrointestinal tract.Present studies demonstrate that GIST is mainly driven by a mutated c-KIT or platelet-derived growth factor receptor alpha gene.Histologically,GIST is usually composed of spindle cells,epithelioid cells,or pleomorphic cells in a bundle or diffuse pattern.GIST cells are generally immunohistochemically positive for CD34,CD117,or DOG-1 expression.GIST is similar to interstitial cells of Cajal around the myenteric plexus of the gastrointestinal tract,and both have a positive c-KIT gene,CD117,and CD34 expression.At present,gastroscopy,colonoscopy,computed tomography,nuclear magnetic resonance and other means are the primary means to diagnosis GIST.At the same time,for unidentified GIST,biopsy is also a necessary means of examination.However,for the treatment of gastrointestinal stromal tumors,oral Gleevec and surgery are present primary treatment methods,which is still limited.However,not all patients are suitable for Gleevec.For some gene mutated sites,Gleevec treatment is ineffective.With the increase of cases of gastrointestinal stromal tumors,targeted therapies for GISTs with different gene loci mutations are urgently needed.

59例血小板源性生长因子受体α突变型胃肠间质瘤的临床病理特征和预后分析

目的血小板源性生长因子受体α(PDGFRA)突变的胃肠间质瘤(GIST)是一种发病率较低的GIST,有关其临床病理特点以及预后的研究很少。本文探讨PDGFRA突变型GIST的临床病理特征及预后因素,以期为治疗提供更多数据参考。方法采用回顾性病例对照研究方法,收集2015年1月至2019年8月期间,复旦大学附属中山医院进行手术切除并经术后病理诊断证实为GIST的患者病历资料,筛选出基因检测为PDGFRA突变型、并排除PDGFRA同义突变、非肿瘤相关死亡和临床病理资料缺失的患者。收集患者临床病理特征资料,并分析影响PDGFRA突变型GIST患者预后的危险因素。结果纳入的59例PDGFRA突变型GIST患者中,男性41例(69.5%),女性18例(30.5%),60岁以下患者31例(52.5%);肿瘤均来源于胃,肿瘤≤5 cm者33例(55.9%),>5 cm者26例(44.1%);核分裂象计数≤5个/50高倍镜视野(HPF)者49例(83.0%);改良美国国立卫生研究院(NIH)危险度分级标准:极低危8例(13.6%),低危25例(42.4%),中危14例(23.7%),高危12例(20.3%);7例PDGFRA第12外显子突变,52例第18外显子突变,其中D842V突变36例。D842V组与非D842V组的临床病理特点比较,差异无统计学意义(均P>0.05)。中位随访21(0~59)个月,全组患者的1年和3年无复发生存率(RFS)分别为96.6%和91.5%,8例出现复发,3例死亡;6例D842V突变的GIST患者术后发生了肿瘤的复发,其中4例服用dasatinib或avapritinib后获得不同程度的肿瘤缓解。log-rank分析显示,与女性相比,男性拥有较好的总生存率(OS)(100%比83.3%,P=0.046);D842V与非D842V、第12外显子与第18外显子突变患者的RFS和OS均相近(均P>0.05)。单因素Cox分析显示,RFS与性别(P=0.010)、肿瘤大小(P=0.042)、核分裂象计数(P=0.003)及NIH危险度分级(P=0.042)有关;而多因素分析结果显示,较高的危险度分级是导致PDGFRA突变型GIST复发的独立危险因素(HR=12.796,95%CI:1.326~123.501,P=0.028),男性的复发风险低于女性(HR=0.154,95%CI:0.028~0.841,P=0.031)。结论性别和改良NIH危险度分级是影响PDGFRA突变型GIST复发的独立因素,而D842V与非D842V,第12外显子与第18外显子突变患者的复发与死亡风险接近。

Coexistence of a c-kit negative gastrointestinal stromal tumor and a gastric mucinous adenocarcinoma

Mazur and Clark introduced the term ＂gastrointestinal stromal tumor＂ （GIST）. These tumors are thought to originate from mesenchymal stem cells that differentiate toward the interstitial cells of Cajal. Activation of c-kit or platelet-derived growth factor receptor alpha （PDGFRA） gene mutation has been shown to be a major force in GIST pathogenesis leading to down-stream phosphorylation of substrate proteins and subsequently activation of networks of signal transduction pathways that regulate cell proliferation,survival, apoptosis, motility and other important cell functions. Immunohistochemically, a great majority of GISTs show strong, diffuse c-kit expression. The diagnosis of GIST is currently based on morphologic features and immunohistochemical demonstration of c-kit （CD117）. However, in some cases c-kit immunoreactivity is weak or undetectable.