Retrospective analysis of extra-gastrointestinal stromal tumors

AIM:To investigate the clinicopathologic features of patients with extra-gastrointestinal stromal tumors(EGISTs)in South Korea.METHODS:A total of 51 patients with an EGIST were identified.The clinicopathologic features,including sex,age,location,tumor size,histology,mitotic rate,immunohistochemical features,genetic status and survival data,were analyzed.RESULTS:The median age was 55 years(range:29-80years),and male:female ratio was 1:1.04.The most common site was in the mesentery(n=15)followed by the retroperitoneum(n=13)and omentum(n=8).The median tumor size was 9.0 cm(range:2.6-30.0cm)and the median mitotic rate was 5.0/50HPF.(1/50-185/50).KIT was analyzed in 16,which revealed 10cases with wild-type KIT and 6 cases with an exon 11mutation.Among 51 patients,31 patients had undergone surgery,and 10 had unresectable disease and had taken palliative imatinib,which resulted in 22.7 mo of progression-free survival.Of the patients who had undergone surgery,18 did not take adjuvant imatinib,and 8 of these were categorized as"high risk"according to the risk criteria.However,the relapse-free survival was not different(P=0.157)between two groups.CONCLUSION:Because the biologic behaviors of GISTs differ according to the location of the tumor,a more stratified strategy is required for managing EGISTs including incorporation of molecular features.

Primary Hepatic Extra-gastrointestinal Stromal Tumors:Molecular Pathogenesis,Immunohistopathology,and Treatment

Gastrointestinal stromal tumors are the most common mesenchymal tumors of the gastrointestinal tract.They originate from the interstitial cells of Cajal and are usually found in extrahepatic gastrointestinal sites.However,a small subset are derived from the liver and are known as primary hepatic gastrointestinal stromal tumors(PHGIST).They have a poor prognosis and are historically difficult to diagnose.Our objective was to review and update the latest evidence-based knowledge concerning PHGIST,with a focus on epidemiology,etiology,pathophysiology,clinical presentation,histopathology,and treatment.These tumors are usually found incidentally,occur sporadically,and are associated with mutations of KIT and PDGFRA genes.PHGIST is a diagnosis of exclusion,as it has the same molecular,immunochemistry and histological appearance as gastrointestinal stromal tumors(GIST).Thus,imaging,such as positron emission tomography-computed tomography(PET-CT)must be used to rule out metastatic GIST before a diagnosis can be made.However,with mutation analysis and pharmacological advances,tyrosine kinase inhibitors are typically pursued with or without surgical intervention.Other potential treatments include transcatheter arterial chemoembolization and tumor ablation.However,these are typically considered palliative options.As there are only a limited number of publications regarding PHGIST,data concerning morbidity and mortality are not yet available.Immunohistopathology can help develop screening guidelines and evaluating resistance to treatment.

Extragastrointestinal stromal tumors with diffuse membranous distribution with bleeding:A case report

BACKGROUND Extragastrointestinal stromal tumors(EGIST)and gastrointestinal stromal tumors are of similar pathological type and form.Here we report a rare case of EGIST diffusely distributed in membranous tissue in abdominal cavity,the feature of which included diffuse tumors at membranous tissue in entire abdominal cavity and spontaneous bleeding of the tumors.CASE SUMMARY The patient was a 71-year man and hospitalized due to continuous pain at lower abdomen for more than 10 days.Upon physical examination,the patient had flat and tough abdomen with mild pressing pain at lower abdomen,no obvious abdominal mass was touchable,and shifting dullness was positive.Positron emission tomography-computed tomography(CT)showed that in his peritoneal cavity,there were multiple nodules of various sizes,seroperitoneum,multiple enlarged lymph nodes in abdominal/pelvic cavity and right external ilium as well as pulmonary nodules.Plain CT scanning at epigastrium/hypogastrium/pelvic cavity+enhanced three-dimensional reconstruction revealed multiple soft tissue nodules in abdominal/pelvic cavity,peritoneum and right groin.Tumor marker of carbohydrate antigen 125 was 808 U/mL,diffuse tuberous tumor was seen in abdominal/pelvic cavity during operation with hematocelia,and postoperative pathological examination confirmed EGIST.Imatinib was administered with better therapeutic effect.CONCLUSION Gene testing showed breast cancer susceptibility gene 1 interacting protein C-terminal helicase 1 and KIT genovariation,and the patient was treated with imatinib follow-up visit found that his clinical symptoms disappeared and the tumor load alleviated obviously via imageological examination.

Insulin-like growth factor 2 targets IGF1R signaling transduction to facilitate metastasis and imatinib resistance in gastrointestinal stromal tumors

BACKGROUND Gastrointestinal stromal tumors(GISTs)are typical gastrointestinal tract neoplasms.Imatinib is the first-line therapy for GIST patients.Drug resistance limits the long-term effectiveness of imatinib.The regulatory effect of insulin-like growth factor 2(IGF2)has been confirmed in various cancers and is related to resistance to chemotherapy and a worse prognosis.AIM To further investigate the mechanism of IGF2 specific to GISTs.METHODS IGF2 was screened and analyzed using Gene Expression Omnibus(GEO:GSE225819)data.After IGF2 knockdown or overexpression by transfection,the phenotypes(proliferation,migration,invasion,apoptosis)of GIST cells were characterized by cell counting kit 8,Transwell,and flow cytometry assays.We used western blotting to evaluate pathway-associated and epithelial-mesenchymal transition(EMT)-associated proteins.We injected transfected cells into nude mice to establish a tumor xenograft model and observed the occurrence and metastasis of GIST.RESULTS Data from the GEO indicated that IGF2 expression is high in GISTs,associated with liver metastasis,and closely related to drug resistance.GIST cells with high expression of IGF2 had increased proliferation and migration,invasiveness and EMT.Knockdown of IGF2 significantly inhibited those activities.In addition,OEIGF2 promoted GIST metastasis in vivo in nude mice.IGF2 activated IGF1R signaling in GIST cells,and IGF2/IGF1R-mediated glycolysis was required for GIST with liver metastasis.GIST cells with IGF2 knockdown were sensitive to imatinib treatment when IGF2 overexpression significantly raised imatinib resistance.Moreover,2-deoxy-D-glucose(a glycolysis inhibitor)treatment reversed IGF2 overexpressionmediated imatinib resistance in GISTs.CONCLUSION IGF2 targeting of IGF1R signaling inhibited metastasis and decreased imatinib resistance by driving glycolysis in GISTs.

Systemic therapy in gastrointestinal stromal tumors

Gastrointestinal stromal tumors(GISTs)are the most common type of soft tissue sarcoma in the gastrointestinal tract.Most GISTs have been attributed to activated gain-of-function mutations in either KIT or platelet-derived growth factor receptorα,making these molecular features essential targets for therapeutic interventions.Although surgery is the standard treatment for localized GISTs,patients often experience relapse and disease progression even after surgery.In recent years,targeted therapy has significantly improved the prognosis of patients with advanced GISTs.Imatinib mesylate,a KIT inhibitor,is the first-line treatment for advanced GISTs and has revolutionized the treatment of this disease.However,drug resistance remains a major issue with imatinib treatment,as a significant majority of patients become resistant to imatinib either after initiation or after 2–3 years of treatment.Consequently,novel tyrosine kinase inhibitors such as sunitinib,regorafenib,ripretinib,and avapritinib have been introduced to address drug resistance.Immunotherapy has emerged as a potential approach for the treatment of advanced GISTs.This review comprehensively summarizes the pathogenesis of GISTs and the development of targeted therapies and immunotherapies,provides an overview of the emergence of drug resistance in advanced GISTs,and discusses the challenges and prospects associated with the treatment of GISTs.

Malignant extra-gastrointestinal stromal tumor of the pancreas:Report of two cases and review of the literature

Gastrointestinal stromal tumors(GISTs)are mesenchymal tumors that arise from the gastrointestinal tract.In rare cases,these tumors are found in intra-abdominal sites unrelated to the gastrointestinal tract,such as the mesentery,omentum and retroperitoneum.However,pancreatic extra-gastrointestinal stromal tumors are extremely rare,with only 14 previous cases reported.A 61-year-old man with no clinical symptoms had a routine check-up,during which an abdominal mass located in the pancreas tail was detected.Abdominal surgery was performed with resection of the pancreas tail and the spleen,and he was diagnosed with lowrisk GISTs.Another 60-year-old man with no clinical symptoms underwent Computed tomography which revealed a well-demarcated tumor,6 cm in diameter,in the head of the pancreas.He was diagnosed with pancreatic GISTs.Here,we describe two rare cases of pancreatic GISTs and review the cases previously reported in the literature.

Computed tomography radiogenomics:A potential tool for prediction of molecular subtypes in gastric stromal tumor

BACKGROUND Preoperative knowledge of mutational status of gastrointestinal stromal tumors(GISTs)is essential to guide the individualized precision therapy.AIM To develop a combined model that integrates clinical and contrast-enhanced computed tomography(CE-CT)features to predict gastric GISTs with specific genetic mutations,namely KIT exon 11 mutations or KIT exon 11 codons 557-558 deletions.METHODS A total of 231 GIST patients with definitive genetic phenotypes were divided into a training dataset and a validation dataset in a 7:3 ratio.The models were constructed using selected clinical features,conventional CT features,and radiomics features extracted from abdominal CE-CT images.Three models were developed:ModelCT sign,modelCT sign+rad,and model CTsign+rad+clinic.The diagnostic performance of these models was evaluated using receiver operating characteristic(ROC)curve analysis and the Delong test.RESULTS The ROC analyses revealed that in the training cohort,the area under the curve(AUC)values for model_(CT sign),model_(CT sign+rad),and modelCT_(sign+rad+clinic)for predicting KIT exon 11 mutation were 0.743,0.818,and 0.915,respectively.In the validation cohort,the AUC values for the same models were 0.670,0.781,and 0.811,respectively.For predicting KIT exon 11 codons 557-558 deletions,the AUC values in the training cohort were 0.667,0.842,and 0.720 for model_(CT sign),model_(CT sign+rad),and modelCT_(sign+rad+clinic),respectively.In the validation cohort,the AUC values for the same models were 0.610,0.782,and 0.795,respectively.Based on the decision curve analysis,it was determined that the model_(CT sign+rad+clinic)had clinical significance and utility.CONCLUSION Our findings demonstrate that the combined modelCT_(sign+rad+clinic)effectively distinguishes GISTs with KIT exon 11 mutation and KIT exon 11 codons 557-558 deletions.This combined model has the potential to be valuable in assessing the genotype of GISTs.

Gastric IgG4-related disease mimicking a gastrointestinal stromal tumor in a child: A case report

BACKGROUND Gastric IgG4-related disease(IgG4-RD)is rarely encountered in clinical practice,and especially more so among pediatric patients.To our knowledge,this is the first report of IgG4-RD presenting as a calcifying gastric mass in a child.We describe how this entity was difficult to differentiate from a gastrointestinal stromal tumor(GIST)imaging-based approaches.Therefore,this case highlights the importance of considering IgG4-RD in the differential diagnosis of gastric tumor before performing surgical resection,especially to distinguish it from malignancy to avoid unnecessary surgery.CASE SUMMARY The patient suffered from epigastric pain for several days.Panendoscopy and computed tomography scan revealed a submucosal tumor.Differential diagnoses included GIST,leiomyoma,teratoma,and mucinous adenocarcinoma.However,laparoscopic proximal gastrectomy allowed for the definitive diagnosis of IgG4-related stomach disease.CONCLUSION We emphasize the importance of considering IgG4-RD in the differential diagnosis of gastric submucosal tumors before performing surgical resection.

Postoperative encapsulated hemoperitoneum in a patient with gastric stromal tumor treated by exposed endoscopic full-thickness resection: A case report

BACKGROUND Gastric stromal tumors,originating from mesenchymal tissues,are one of the most common tumors of the digestive tract.For stromal tumors originating from the muscularis propria,compared with conventional endoscopic submucosal dissection(ESD),endoscopic full-thickness resection(EFTR)can remove deep lesions and digestive tract wall tumors completely.However,this technique has major limitations such as perforation,postoperative bleeding,and post-polypectomy syndrome.Herein,we report a case of postoperative serous surface bleeding which formed an encapsulated hemoperitoneum in a patient with gastric stromal tumor that was treated with exposed EFTR.Feasible treatment options to address this complication are described.CASE SUMMARY A 47-year-old male patient had a hemispherical protrusion found during gastric endoscopic ultrasonography,located at the upper gastric curvature adjacent to the stomach fundus,with a smooth surface mucosa and poor mobility.The lesion was 19.3 mm×16.1 mm in size and originated from the fourth ultrasound layer.Computed tomography(CT)revealed no significant evidence of lymph node enlargement or distant metastasis.Using conventional ESD technology for mucosal pre-resection,exposed EFTR was performed to resect the intact tumor in order to achieve a definitive histopathological diagnosis.Based on its morphology and immunohistochemical expression of CD117 and DOG-1,the lesion was proven to be consistent with a gastric stromal tumor.Six days after exposed EFTR,CT showed a large amount of encapsulated fluid and gas accumulation around the stomach.In addition,gastroscopy suggested intracavitary bleeding and abdominal puncture drainage indicated serosal bleeding.Based on these findings,the patient was diagnosed with serosal bleeding resulting in encapsulated abdominal hemorrhage after exposed EFTR for a gastric stromal tumor.The patient received combined treatments,such as hemostasis under gastroscopy,gastrointestinal decompression,and abdominal drainage.All examinations were normal within six months of follow-up.CONCLUSION This patient developed serous surface bleeding in the gastric cavity following exposed EFTR.Serosal bleeding resulting in an encapsulated hemoperitoneum is rare in clinical practice.The combined treatment may replace certain surgical techniques.

Relationship between multi-slice computed tomography features and pathological risk stratification assessment in gastric gastrointestinal stromal tumors

BACKGROUND Computed tomography(CT)imaging features are associated with risk stratification of gastric gastrointestinal stromal tumors(GISTs).AIM To determine the multi-slice CT imaging features for predicting risk stratification in patients with primary gastric GISTs.METHODS The clinicopathological and CT imaging data for 147 patients with histologically confirmed primary gastric GISTs were retrospectively analyzed.All patients had received dynamic contrast-enhanced CT(CECT)followed by surgical resection.According to the modified National Institutes of Health criteria,147 lesions were classified into the low malignant potential group(very low and low risk;101 lesions)and high malignant potential group(medium and high-risk;46 lesions).The association between malignant potential and CT characteristic features(including tumor location,size,growth pattern,contour,ulceration,cystic degeneration or necrosis,calcification within the tumor,lymphadenopathy,enhancement patterns,unenhanced CT and CECT attenuation value,and enhancement degree)was analyzed using univariate analysis.Multivariate logistic regression analysis was performed to identify significant predictors of high malignant potential.The receiver operating curve(ROC)was used to evaluate the predictive value of tumor size and the multinomial logistic regression model for risk classification.RESULTS There were 46 patients with high malignant potential and 101 with low-malignant potential gastric GISTs.Univariate analysis showed no significant differences in age,gender,tumor location,calcification,unenhanced CT and CECT attenuation values,and enhancement degree between the two groups(P>0.05).However,a significant difference was observed in tumor size(3.14±0.94 vs 6.63±3.26 cm,P<0.001)between the low-grade and high-grade groups.The univariate analysis further revealed that CT imaging features,including tumor contours,lesion growth patterns,ulceration,cystic degeneration or necrosis,lymphadenopathy,and contrast enhancement patterns,were associated with risk stratification(P<0.05).According to binary logistic regression analysis,tumor size[P<0.001;odds ratio(OR)=26.448;95%confidence interval(CI):4.854-144.099)],contours(P=0.028;OR=7.750;95%CI:1.253-47.955),and mixed growth pattern(P=0.046;OR=4.740;95%CI:1.029-21.828)were independent predictors for risk stratification of gastric GISTs.ROC curve analysis for the multinomial logistic regression model and tumor size to differentiate high-malignant potential from low-malignant potential GISTs achieved a maximum area under the curve of 0.919(95%CI:0.863-0.975)and 0.940(95%CI:0.893-0.986),respectively.The tumor size cutoff value between the low and high malignant potential groups was 4.05 cm,and the sensitivity and specificity were 93.5%and 84.2%,respectively.CONCLUSION CT features,including tumor size,growth patterns,and lesion contours,were predictors of malignant potential for primary gastric GISTs.

Optical second-harmonic generation imaging for identifying gastrointestinal stromal tumors

Gastrointestinal stromal tumors(GISTs)are the most common mesenchymal tumors arising in the digest tract.It brings a challenge to diagnosis because it is asymptomatic clinically.It is well known that tumor development is often accompanied by the changes in the morphology of collagen fibers.Nowadays,an emerging optical imaging technique,second-harmonic generation(SHG),can directly identify collagen fibers without staining due to its noncentrosymmetric properties.Therefore,in this study,we attempt to assess the feasibility of SHG imaging for detecting GISTs by monitoring the morphological changes of collagen fibers in tumor microenvironment.We found that collagen alterations occurred obviously in the GISTs by comparing with normal tissues,and furthermore,two morphological features from SHG images were extracted to quantitatively assess the morphological difference of collagen fibers between normal muscular layer and GISTs by means of automated image analysis.Quantitative analyses show a significant difference in the two collagen features.This study demonstrates the potential of SHG imaging as an adjunctive diagnostic tool for label-free identification of GISTs.

Neurofibromatosis type 1 with multiple gastrointestinal stromal tumors:A case report

BACKGROUND Neurofibromatosis type 1(NF1)is characterized by café-au-lait patches on the skin and the presence of neurofibromas.Gastrointestinal stromal tumor(GIST)is the most common non-neurological tumor in NF1 patients.In NF1-associated GIST,KIT and PDGFRA mutations are frequently absent and imatinib is ineffective.Surgical resection is first-line treatment.CASE SUMMARY A 56-year-old woman with NF1 was hospitalized because of an incidental pelvic mass.Physical examination was notable for multiple café-au-lait patches and numerous subcutaneous soft nodular masses of the skin of the head,face,trunk,and limbs.Her abdomen was soft and nontender.No masses were palpated.Digital rectal examination was unremarkable.Abdominal computed tomography was suspicious for GIST or solitary fibrous tumor.Laparoscopy was performed,which identified eight well-demarcated masses in the jejunum.All were resected and pathologically diagnosed as GISTs.The patient was discharged on day 7 after surgery without complications.No tumor recurrence was evident at the 6-mo follow-up.CONCLUSION Laparoscopy is effective for both diagnosis and treatment of NF1-associated GIST.

Sunitinib-induced hyperammonemic encephalopathy in metastatic gastrointestinal stromal tumors:A case report

BACKGROUND Sunitinib,a multi-targeted tyrosine kinase inhibitor(TKI),has been approved for the salvage treatment of gastrointestinal stromal tumors(GIST).Hyperammonemic encephalopathy is a rare but severe complication of sunitinib use.Here,we present the case of a 66-year-old male with metastatic GIST without underlying liver cirrhosis who developed sunitinib-induced hyperammonemic encephalopathy.CASE SUMMARY A 66-year-old male with metastatic GIST was admitted because of reduced consciousness.Imatinib was administered as the first-line systemic therapy.He experienced repeated episodes of peritonitis due to tumor perforation,and surgery was performed.Progressive disease was confirmed based on increased liver metastasis,and sunitinib was initiated as a salvage treatment.However,23 d after the third course of sunitinib,he presented to the emergency room with an episode of altered consciousness and behavioral changes.Based on the patient clinical history and examination findings,sunitinib-induced encephalopathy was suspected.Sunitinib was discontinued,and the patient was treated for hyperammonemia.The patient had a normal level of consciousness four days later,and the serum ammonia level gradually decreased.No further neurological symptoms were reported in subsequent follow-ups.CONCLUSION TKI-induced hyperammonemic encephalopathy is potentially life-threatening.Patients receiving TKIs experiencing adverse reactions should undergo systemic evaluation and prompt treatment.

Giant hepatic extra-gastrointestinal stromal tumor treated with cytoreductive surgery and adjuvant systemic therapy:A case report and review of literature

BACKGROUND Primary extra-gastrointestinal stromal tumors(E-GIST)of the liver are rare.The clinical presentation may range from asymptomatic to bleeding or manifestations of mass effect.Oncologic surgery followed by adjuvant therapy with imatinib is the standard of care.However,under specific circumstances,a cytoreductive approach may represent a therapeutic option.We describe herein the case of an 84-year-old woman who presented with a tender,protruding epigastric mass.Abdominal computed tomography scan revealed a large,heterogeneous mass located across segments III,IV,V,and VIII of the liver.The initial approach was transarterial embolization of the tumor,which elicited no appreciable response.Considering the large size and central location of the tumor and the advanced age of the patient,non-anatomic complete resection was indicated.Due to substantial intraoperative bleeding and hemodynamic instability,only a near-complete resection could be achieved.Histopathology and immunohistochemical staining confirmed the diagnosis of primary E-GIST of the liver.Considering the risk/benefit ratio for therapeutic options,debulking surgery may represent a strategy to control pain and prolong survival.CASE SUMMARY Here,we present a case report of a patient diagnosed with E-GIST primary of the liver,which was indicated a cytoreductive surgery and adjuvant therapy with imatinib.CONCLUSION E-GIST primary of the liver is a rare conditional,the treatment is with systemic therapy and total resection surgery.However,a cytoreductive surgery will be necessary when a complete resection is no possible.

Primary Extra-Gastrointestinal Stromal Tumor (GIST) arising from mesentery of small bowel and presenting as abdominal mass: A rare entity

Introduction: Majority of mesenchymal tumors of gastrointestinal tract are Gastrointestinal Stromal Tumor (GIST). It is, however, a rare tumor, accounting for less than 1% of primary gastrointestinal (GI) neoplasms. Though, these tumors are refractory to conventional chemotherapy or radiotherapy but show a good response to targeted adjuvant chemotherapy with tyrosine kinase inhibitors following surgical resection. Case Report: we report here a case of primary Extra-GIST tumor arising from mesentry of small bowel near duodeno-jejunal junction in a 69 years old male patient. The patient presented with a palpable mass in upper abdomen for past 15 days. On examination, a non-tender mobile lump of size around 17 × 10 cm, with bosselated surface and firm in consistency was palpable involving epigastric, left hypochondrium and umbilical region. Contrast enhanced computed tomography of abdomen revealed a heterogenous mesentric mass. On surgical intervention a mass was found involving mesentery near dudenojejunal junction without involvement of gastrointestinal tract. Complete surgical resection of the tumor was done and adjuvant chemotherapy with Imatinib mesylate was started as HPE revealing GIST with mitotic index of >10/50 HPF and 17 × 10 cm size placed the patient in high risk category. Patient was discharged on 12th of post-operative day with advice of regular follow-up. Conclusion: GIST occurrence is not restricted to bowel but can involve unusual sites also. The mainstay of treatment remains surgical resection with adequate margin. In cases where tumour has malignant potential (high mitotic figures on histopathology) adjuvent treatment with tyrosine kinase may prevent or delay relapse.

Extra-gastrointestinal Stromal Tumor :Clinical Characteristics,Diagnosis, Treatment, and Prognosis

Objective:To explore the clinicopathological characteristics,treatment and prognosis of extrogastrointestinal stromal tumor(EGIST).Methods:In our study,Clinicopathological data of EGISTs from January 2010 to October 2014were systematically investigated.Pathology results were rechecked.Patients also were followed Up.Prognostic factors were evaluated using Cox proportional hazard models and univariate and multivariate with Log-rank test.Results:An amount of EGISTs cases were selected due to inclusion criteria,including 28males and 26Females,with age from 18 To78 years(median,58).Patients were follwed up.12cases were dead.The 1-,3-,5-year survival rates were 91%,75%,66%.Patients undergoing R0 resection had a better 5-year overall survival rate than those undergoing R1 resection(75%vs46%,P<0.05).For patients with high risk of recurrence after surgery,the 5-year overall survival rate was 62%and 40%respectively(P<0.05).Conclusions:Tumor size,mitotic count and tumor rupture affect the prognosis of patients after resection of primary EGISTs independently.Adjuvant imatinib can effectively improve the prognosis of the patients with high risk of recurrence,and the survival rate of patients after surgery.Surgical resection is the main treatment of EGIST,and R0 resection helps to prolong the survival time.

TATA-box-binding protein-associated factor 15 is a novel biomarker that promotes cell proliferation and migration in gastrointestinal stromal tumor

BACKGROUND Gastrointestinal stromal tumor(GIST)is a common neoplasm with high rates of recurrence and metastasis,and its therapeutic efficacy is still not ideal.There is an unmet need to find new molecular therapeutic targets for GIST.TATA-boxbinding protein-associated factor 15(TAF15)contributes to the progress of various tumors,while the role and molecular mechanism of TAF15 in GIST progression are still unknown.AIM To explore new molecular therapeutic targets for GIST and understand the biological role and underlying mechanisms of TAF15 in GIST progression.METHODS Proteomic analysis was performed to explore the differentially expressed proteins in GIST.Western blotting and immunohistochemical analysis were used to verify the expression level of TAF15 in GIST tissues and cell lines.Cell counting kit-8,colony formation,wound-healing and transwell assay were executed to detect the ability of TAF15 on cell proliferation,migration and invasion.A xenograft mouse model was applied to explore the role of TAF15 in the progression of GIST.Western blotting was used to detect the phosphorylation level and total level of RAF1,MEK and ERK1/2.RESULTS A total of 1669 proteins were identified as differentially expressed proteins with 762 upregulated and 907 downregulated in GIST.TAF15 was selected for the further study because of its important role in cell proliferation and migration.TAF15 was significantly over expressed in GIST tissues and cell lines.Overexpression of TAF15 was associated with larger tumor size and higher risk stage of GIST.TAF15 knockdown significantly inhibited the cell proliferation and migration of GIST in vitro and suppressed tumor growth in vivo.Moreover,the inhibition of TAF15 expression significantly decreased the phosphorylation level of RAF1,MEK and ERK1/2 in GIST cells and xenograft tissues,while the total RAF1,MEK and ERK1/2 had no significant change.CONCLUSION TAF15 is over expressed in GIST tissues and cell lines.Overexpression of TAF15 was associated with a poor prognosis of GIST patients.TAF15 promotes cell proliferation and migration in GIST via the activation of the RAF1/MEK/ERK signaling pathway.Thus,TAF15 is expected to be a novel latent molecular biomarker or therapeutic target of GIST.

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 heterogeneous in 11.In 1 of 11 patients who underwent both CT and MRI,the tumor was homogenous on CT scan and heterogeneous on MRI.Eight patients were classified as high risk according to the modified recurrent risk classification system of NIH.CONCLUSION:Rectal GISTs usually manifest as large,well-circumscribed,exophytic masses with moderate and heterogeneous enhancement on CT and MRI.The invasion of adjacent organs,bowel obstruction and local adenopathy are uncommon.

A gist of gastrointestinal stromal tumors: A review

Gastrointestinal stromal tumors (GISTs) have been recognized as a biologically distinctive tumor type, different from smooth muscle and neural tumors of the gastrointestinal tract (GIT). They constitute the majority of gastrointestinal mesenchymal tumors of the GIT and are known to be refractory to conventional chemotherapy or radiation. They are defined and diagnosed by the expression of a proto-oncogene protein detected by immunohistochemistry which serves as a crucial diagnostic and therapeutic target. The identification of these mutations has resulted in a better understanding of their oncogenic mechanisms. The remarkable antitumor effects of the molecular inhibitor imatinib have necessitated accurate diagnosis of GIST and their distinction from other gastrointestinal mes-enchymal tumors. Both traditional and minimally invasive surgery are used to remove these tumors with minimal morbidity and excellent perioperative outcomes. The revolutionary use of specific, molecularlytargeted therapies, such as imatinib mesylate, reduces the frequency of disease recurrence when used as an adjuvant following complete resection. Neoadjuvant treatment with these agents appears to stabilize disease in the majority of patients and may reduce the extent of surgical resection required for subsequent complete tumor removal. The important interplay between the molecular genetics of GIST and responses to targeted therapeutics serves as a model for the study of targeted therapies in other solid tumors. This review summarizes our current knowledge and recent advances regarding the histogenesis, pathology, molecular biology, the basis for the novel targeted cancer therapy and current evidence based management of these unique tumors.

Molecular basis and management of gastrointestinal stromal tumors

Molecularly targeted agents have dramatically impacted the management of several cancers. Targeting KIT has led to a new treatment paradigm in gastrointestinal stromal tumors (GISTs). KIT is a cell surface receptor with tyrosine kinases that, upon binding of its ligand, stem cell factor, activates various signaling pathways. Imatinib and sunitinib, both tyrosine kinase inhibitors directed to KIT, were approved for firstand secondline treatment of metastatic and unresectable GISTs. In this article, we will review the molecular pathogenesis of GISTs followed by a discussion of imatinib and sunitinib’s role in the treatment of GISTs. Finally, we will introduce novel therapeutic options for imatiniband sunitinib-resistant GISTs.