Marker For Gastrointestinal Stromal Tumors Research Articles

DOG1 as a novel antibody-drug conjugate target for the treatment of multiple gastrointestinal tumors and liver metastasis.

Discovered On Gastrointestinal stromal tumors protein 1 (DOG1), a major calcium-activated chloride channel, has been used as a common diagnostic marker for gastrointestinal stromal tumors. However, the therapeutic application of DOG1 was not well defined. Here, we aim to investigate its potential as a therapeutic target for an antibody-drug conjugate (ADC) in various cancers of the alimentary tract and metastasis. The DOG1 expression profile was determined among TCGA samples and tissue microarrays. High levels of DOG1 expression were ubiquitously observed in multiple cancer samples from the alimentary tract determined by TCGA samples and tissue microarrays. Circulating tumor cells isolated from metastatic colon cancer patients were also positive for DOG1 expression. The mechanisms of anti-DOG1 antibody were investigated by dual-luciferase reporter assay. The anti-DOG1 antibody could inhibit proliferation and metastasis via p53 signaling in limited cancer cell lines. The anti-DOG1 antibody was conjugated with a microtubule inhibitor DM4, to construct a new anti-DOG1-DM4-ADC to strengthen its activity. The anti-DOG1-DM4-ADC showed cytotoxicity at the nanomolar level in vitro. In the murine xenograft tumor models, treatment of anti-DOG1-DM4-ADC achieved a significant tumor growth inhibition rate. Our study indicates that anti-DOG1-DM4-ADC may be promising therapeutic molecules for DOG1-positive alimentary tract tumors and may be effective in inhibiting recurrence after curative resection of liver metastases of colorectal origin.

A Rare Case of Gastrointestinal Stromal Tumor of the Abdominal Wall

Gastrointestinal stromal tumors (GIST) are rarely encountered in medical practice, developing with predilection in people over 40 years old. Their starting point is found in the digestive tract, and can appear anywhere along it. Normally, in the human body cells go through the processes of development, division and then apoptosis. In the case of gastro-intestinal stromal tumors, the cells divide continuously and the process of apoptosis is no longer carried out, forming these tumors, which can be benign or malignant. The essential medical treatment used in the case of gastrointestinal stromal tumors is Imatinib, which has the role of preventing the growth or even regression in size of the tumor in most cases. The specificity marker for GIST is represented by c-KIT protein, and immunohistochemically, the majority of gastrointestinal stromal tumors show positivity for CD34 and c-KIT. There are also extragastro-intestinal stromal tumors, for example located in the liver, duodenum, pancreas, but they are extremely rare, being considered rather as metastases from the primary tumor.

S1697 Biliary Schwannoma in a Post-Liver Transplant Patient Presenting as Biliary Obstruction

Introduction: Schwannomas are benign, mesenchymal-derived neoplasms which present as solid, slow growing tumors. They can rarely be observed in the gastrointestinal (GI) tract, with very limited reports of them occurring in the biliary system. In this case, we describe a bile duct schwannoma in a post-liver transplant patient. Case Description/Methods: A 77-year-old man with a history of alcohol-related cirrhosis with hepatocellular carcinoma treated with orthotopic liver transplantation 16 years prior, and end stage renal disease on hemodialysis presented with jaundice. Labs demonstrated new elevations in his liver enzymes: AST 181 U/L, ALT 189 U/L, alkaline phosphatase 625 U/L, total bilirubin (TB) 7.9 mg/dL, and direct bilirubin 5.0 mg/dL. A magnetic resonance cholangiopancreatography was performed and demonstrated a 16 x 15 x 11 mm enhancing mass causing abrupt narrowing of the mid common bile duct (CBD) with upstream duct dilation to 10 mm ( Figure A) without other discrete mass identified. A follow-up endoscopic ultrasound confirmed a hypoechoic mass in the mid CBD and fine needle biopsy was obtained. An endoscopic retrograde cholangiopancreatography was subsequently performed, which demonstrated a severe biliary stricture at the level of the prior biliary anastomosis which was treated with balloon dilation and placement of a covered metal stent. The procedure was complicated by post-sphincterotomy bleed and mild post-ERCP pancreatitis. His liver enzymes failed to improve, and his TB progressively worsened to 23.3 mg/dL. Pathology returned showing a low-grade spindle cell tumor (Figure B), with staining positive for S100 (Figure C) and negative for CD117 and desmin, consistent with a diagnosis of schwannoma. Surgical intervention was not pursued, in line with his goals of care, and he was ultimately transitioned to comfort-oriented care and passed 5 days after admission. Discussion: Schwannomas are rare neoplasms which can arise from the nonepithelial wall of the GI tract containing nerve fibers. They are composed of highly cellular spindle cells which stain positive for vimentin (marker of mesenchymal origin) and S100 protein (marker of nerve sheath origin), and negative for CD117 (marker of GI stromal tumors) and desmin (muscle cell marker). Neoplasms can often be suspected in late presentations of post-transplant biliary obstruction. To our knowledge, this is the first case report of a biliary schwannoma occurring at the site of a biliary anastomosis in a liver transplant patient.Figure 1.: A) MRCP T1-weighted coronal image demonstrating a 16 x 15 x 11 mm enhancing mass with diffusion restriction (yellow arrow) at the mid common bile duct causing an abrupt biliary stricture with upstream dilation, B) 10x magnification H&E showing spindled, wavy nuclei in a fibroblastic stroma consistent with a spindle cell neoplasm in a background of unremarkable columnar biliary epithelium, C) 10x magnification S100 immunohistochemical stain showing diffuse nuclear and granular cytoplasmic positivity consistent with nerve sheath origin.

Onodera's Prognostic Nutritional Index is a novel and useful prognostic marker for gastrointestinal stromal tumors.

BACKGROUNDImmunoinflammatory markers such as the peripheral blood neutrophil-to-lymphocyte ratio (NLR) and the platelet-to-lymphocyte ratio (PLR) have gained considerable attention as prognostic markers in gastrointestinal stromal tumors (GISTs). AIMTo assess the prognostic value of Onodera’s Prognostic Nutritional Index (OPNI) for GISTs.METHODSAll patients who had undergone surgical resection for a primary, localized GIST from 2009 to 2016 at our cancer center were initially and retrospectively identified. Recurrence-free survival (RFS) was calculated by the Kaplan-Meier method and compared by the log-rank test. We used multivariate Cox proportional hazard regression models to identify associations with outcome variables.RESULTSA total of 235 GISTs were identified and included for analysis under our inclusion criteria. Univariate and multivariate analyses both identified the OPNI as an independent prognostic marker, and the OPNI was associated with the primary site, tumor size, mitotic index, tumor rupture, necrosis, and modified NIH risk classification. Low OPNI (< 51.30; hazard ratio = 5.852; 95% confidence interval: 1.072–31.964; P = 0.0414) was associated with worse RFS. The 2- and 5-year RFS rates of the patients with a low OPNI were 92.83% and 76.22%, respectively, whereas 100% and 98.41% were achieved by the patients with a high OPNI.CONCLUSIONThe preoperative OPNI is a novel and useful prognostic marker for GISTs.

Prognostic value of Onodera\u2019s nutritional index for intermediate- and high-risk gastrointestinal stromal tumors treated with or without tyrosine kinase inhibitors

BackgroundImmunoinflammatory and nutritional markers, such as the peripheral blood neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR) and Onodera’s prognostic nutritional index (OPNI), have gained considerable attention and have been preliminarily revealed as prognostic markers of gastrointestinal stromal tumors (GISTs).MethodsIn this study, we first investigated the prognostic value of OPNI in GISTs treated with or without TKIs based on the propensity score matching (PSM) method. All of the patients had received surgical resection for primary GIST, and data from 2010 to 2018 were initially and retrospectively identified from our gastrointestinal center. Recurrence-free survival (RFS) was calculated by the Kaplan–Meier method and compared by the log-rank test.ResultsThe patients were divided into groups treated and not treated with TKIs, and we used the propensity score matching method to homogenize their baseline data. Multivariate Cox proportional hazard regression models were applied to identify associations with outcome variables. A total of 563 GISTs were initially chosen, and 280 of them were included for analysis under the inclusion criteria. After PSM, there were 200 patients included. Multivariate analyses identified OPNI as an independent prognostic marker that was associated with primary site, tumor size, mitotic index, tumor rupture, necrosis, and modified NIH risk classification. Low OPNI (< 42.6; HR 0.409; P < 0.001) was associated with worse RFS.ConclusionsPreoperative OPNI is a novel and useful prognostic marker for GISTs both treated and not treated with TKIs. Higher NLR and PLR have negative effects on RFS.

Identification of low-density lipoprotein receptor class A domain containing 4 (LDLRAD4) as a prognostic indicator in primary gastrointestinal stromal tumors

Background:There is an urgent clinical need to select the patients with resectable gastrointestinal stromal tumors (GISTs) who can benefit from adjuvant treatment after complete resection based on disease recurrence risk stratification. We hypothesized that integrating biomarkers into available risk assessment tools may improve the precision of GIST prognostic predictions. Methods:Candidate genes that may cause GIST progression were identified using the Gene Expression Omnibus dataset GSE20708. Quantitative Real-time was used to confirm the prognostic value of the candidate genes for recurrence-free survival (RFS) in a cohort of 94 patients. Results: Thirty-seven differentially expressed genes between localized tumors and metastatic primary tumors were found; 14 (37.8%) were upregulated and 23 (62.2%) were downregulated in the latter tumors. Low-density lipoprotein receptor class A domain containing 4 (LDLRAD4) was selected for further prognostic analysis. Although LDLRAD4 mRNA expression was not associated with recurrence risk grades as determined by the revised NIH consensus criteria, multivariate Cox regression analysis showed that LDLRAD4 expression (hazard ratio [HR] = 4.403, 95% confidence interval [CI]: 1.822-10.641, P = 0.001), tumor size (HR = 1.174, 95% CI: 1.027-1.342, P = 0.019) and tumor location (HR = 6.291, 95% CI: 1.128-35.080, P = 0.036) were independent prognostic factors for RFS in patients with resectable GISTs. Moreover, the RFS model constructed by these three factors may effectively predict GIST prognosis within the first 2 postsurgical years. Conclusion: Our study identifies LDLRAD4 as a suitable prognostic marker for GISTs. The integration of biomarkers into risk assessment tools may improve the precision of GIST prognostic predictions.

Do GISTs Occur in Rats and Mice? Immunohistochemical Characterization of Gastrointestinal Tumors Diagnosed as Smooth Muscle Tumors in The National Toxicology Program.

The majority of the tumors in the gastrointestinal (GI) tract of rats and mice, with spindle cell morphology, are diagnosed as smooth muscle tumors (SMTs). Similarly, several decades ago human GI tumors with spindle cell morphology were also diagnosed as SMTs. However, later investigations identified most of these tumors in humans as gastrointestinal stromal tumors (GISTs). The GISTs are considered to arise from the interstitial cells of Cajal located throughout the GI tract. Positive immunohistochemical staining with CKIT antibody is a well-accepted diagnostic marker for GISTs in humans. Since there is a considerable overlap between the histomorphology of SMTs and GISTs, it is not possible to distinguish them on hematoxylin and eosin stained sections. As a result, GISTs are not routinely diagnosed in toxicological studies. The current study was designed to evaluate the tumors diagnosed as leiomyoma or leiomyosarcoma in the National Toxicology Program's 2-year bioassays using CKIT, smooth muscle actin, and desmin immunohistochemistry. The results demonstrate that most of the mouse SMTs diagnosed as leiomyoma or leiomyosarcoma are likely GISTs, whereas in rats the tumors are likely SMTs and not GISTs.

KCTD12 is negatively regulated by Kit in gastrointestinal stromal tumors.

Our group has previously demonstrated that pfetin, encoded by the KCTD12 gene, is a strong prognostic biomarker for gastrointestinal stromal tumors (GISTs). However, the underlying mechanisms that control pfetin expression remain unknown. To elucidate the regulatory mechanisms of KCTD12 in GIST, in addition to a possible association between KCTD12 alterations and protein expression, we examined 76 patients with GISTs for KCTD12 mutations by PCR-direct sequence, and compared these results with clinicopathologic data. The function of pfetin in GIST progression was also revealed using GIST T1 cells. In this series, pfetin expression was not observed in 15 cases, and loss of pfetin expression was associated with higher mitotic rate (>5/50HPFs: p = 0.029). There was also a trend between presence of necrosis and loss of pfetin expression but this was not statistically significant (p = 0.09). KCTD12 mutations were frequently observed in 22 out of 76 GISTs (28.9%); however, they did not affect protein expression and were not associated with patients’ prognosis. KCTD12 in vitro knockdown resulted in the accelerated growth of GIST T1 cells, confirming that pfetin functions as a tumor suppressor. KIT knockdown significantly inhibited cellular growth and upregulated the expression of pfetin at both the mRNA and protein level. These findings suggest that GISTs with loss of pfetin expression has proliferative advantage and that higher pfetin expression in GISTs may be indicative of lower expression levels of KIT. This relationship confirms that pfetin is a useful prognostic marker in GISTs.

Expression of neural cell adhesion molecule L1 (CD171) in neuroectodermal and other tumors: An immunohistochemical study of 5155 tumors and critical evaluation of CD171 prognostic value in gastrointestinal stromal tumors.

The neural cell adhesion molecule L1 (CD171) is a multidomain type 1 membrane glycoprotein of the immunoglobulin superfamily important in the nervous system development, kidney morphogenesis, and maintenance of the immune system. Recent studies reported CD171 expression being associated with adverse clinical outcome in different types of cancer and there has been a growing interest in targeting this cell membrane molecule on neoplastic cells by chimeric antigen receptor redirected T lymphocytes or specific antibodies. Nevertheless, conflicting results regarding the prognostic value of CD171 expression in renal cell carcinomas and gastrointestinal stromal tumors were published. In this study, CD171 expression was immunohistochemically analyzed in 5155 epithelial, mesenchymal, melanocytic, and lymphohematopoietic tumors to assess its utility in diagnostic pathology and to pinpoint potential targets for CD171-targeting therapy. A newly developed anti-CD171 rabbit monoclonal antibody, clone 014, was selected from the panel of commercially available CD171 antibodies. Immunohistochemistry was performed using Leica Bond Max automation and multitumor blocks containing up to 60 tumor samples. CD171 was constitutively and strongly expressed in neuroectodermal tumors such as schwannoma, neuroblastoma, and paraganglioma, whereas other mesenchymal tumors including schwannoma mimics showed only rarely CD171 positivity. Frequent CD171-expression was also detected in ovarian serous carcinoma, malignant mesothelioma, and testicular embryonal carcinoma. CD171 immunohistochemistry may have some role in immunophenotypic differential diagnosis of neurogenic tumors and pinpointing potential candidates for anti-CD171 therapy. Though, because of its rare expression and lack of predictive value, CD171 is neither a diagnostic nor prognostic marker for gastrointestinal stromal tumors.

Circulating tumor cells as a prognostic and predictive marker in gastrointestinal stromal tumors: a prospective study.

BackgroundCirculating tumor cells (CTC) are prognostic and predictive for several cancer types. Only limited data exist regarding prognostic or predictive impact of CTC on gastrointestinal stromal tumor (GIST) patients. The aim of our study was to elucidate the role of CTC in GIST patients.ResultsA total of 121 GIST patients and 54 non-GIST samples were enrolled in the study. The cutoff value for ANO1 positive was 3*10−5 and 65 (54%) GIST patients were defined as ANO1 positive. ANO1s were more frequently detected in unresectable patients. Tumor size, mitotic count and risk level were associated with ANO1 detection in resectable GIST patients. The presence of ANO1 significantly correlated with poor disease-free survival (15.3 versus 19.6 months, p = 0.038). Most patients turned ANO1-negative after surgery and inversely, all 21 patients with recurrence turned ANO1-positive with high ANO1 expression levels. Moreover, in the neoadjuvant setting, decline of ANO1 expression level correlated with the response of imatinib.MethodsCells from peripheral blood mononuclear cells tested positive for anoctamin 1, calcium activated chloride channel, ANO1 (DOG1) were considered as tumor CTC of GISTs. The expression levels of ANO1 were determined using quantitative real-time polymerase chain reaction (qRT-PCR). The highest level of ANO1 expression in non-GIST samples was used as the “cutoff” value.ConclusionANO1 detection by qRT-PCR in peripheral blood is of clinical potential for monitoring recurrence and evaluating therapeutic efficacy of imatinib for GIST patients.

Novel Use for DOG1 in Discriminating Breast Invasive Carcinoma from Noninvasive Breast Lesions.

Aims. DOG1 has proven to be a useful marker of gastrointestinal stromal tumors (GISTs). Recently, DOG1 expression has also been reported in some non-GIST malignant tumors, but the details related to DOG1 expression in breast tissue remain unclear. The aim of this study was to detect the expression of DOG1 in the human breast and to evaluate the feasibility of using DOG1 to discriminate between invasive breast carcinoma and noninvasive breast lesions. Methods and Results. A total of 210 cases, including both invasive and noninvasive breast lesions, were collected to assess DOG1 expression immunohistochemically. DOG1 expression was consistently positive in breast myoepithelial cells (MECs), which was similar to the results obtained for three other MEC markers: calponin, smooth muscle myosin heavy chain (SMMHC), and P63 (P > 0.05 in all). Importantly, DOG1 was useful in discriminating invasive breast carcinoma from noninvasive breast lesions (P < 0.05). Conclusions. DOG1 is a useful marker of breast MECs, and adding DOG1 to the MEC identification panel will provide more sophisticated information when diagnosing uncertain cases in the breast.

Multidisciplinary approach in diagnosis and treatment of gastrointestinal stromal tumors.

Gastrointestinal stromal tumors (GIST) constitute from 0.1% to 3% of all malignant neoplasms of the gastrointestinal tract. Immunohistochemistry plays a key role in the differential diagnosis of GIST and other mesenchymal tumors. The main immunohistochemical marker for GIST is the CD117 (c-Kit), which hyperexpression observed in 95% tumors. When planning treatment of GIST a multidisciplinary approach involving surgeon-oncologist, pathologist, oncologist and radiologist-chemotherapist is required. Surgical treatment remains the main method of treatment in the absence of dissemination of the disease. Tumor size, mitotic index, location of tumor and mutation status of tumor affect on the prognosis of disease progression. Imatinib is a small molecule inhibitor of tyrosine kinase c-Kit, PDGFR, Abl, Bcr-Abl and the main drug in treatment of metastatic GIST. Imatinib is applied in a dose of 400 mg/day, and allows to achieve a clinical improvement (partial response + stabilization) in 90% of patients. Using of imatinib in adjuvant therapy during first year after the operation significantly increases progression-free survival up to 98%. High-risk patients need adjuvant treatment with imatinib for 3 years after the operation according to the ESMO 2012 recommendations. Neoadjuvant therapy with imatinib leads to a reduction of the tumor mass, increase resectability and frequency of performing organ-preserving operations. In case of progression of GIST during therapy with imatinib the last dose may be doubled or a second-line treatment with sunitinib (tyrosine kinase inhibitor of VEGFR, PDGFR, KIT, Flt3) can be used. Sunitinib is applied in a dose of 50 mg/day for 4 weeks daily with an interval of 2 weeks. Treatment with sunitinib allowed to achieve clinical improvement in 24.2% of imatninib-resistant patients. It is necessary to take into account not only the size but also the density and structure of the tumor when performing radiological assessment of response of the tumor to therapy. Currently, the phase II clinical studies are conducted with the aim to investigate the new targeted therapies for the treatment of GIST.

PHH3 as an Ancillary Mitotic Marker in Gastrointestinal Stromal Tumors.

Background:Counting mitoses is subjective and time-consuming. The adjunctive diagnostic utility of a recently reported mitotic marker, phosphohistone H3 (PHH3), was investigated in gastrointestinal stromal tumors (GISTs).Methods:We reviewed 77 GISTs for several proliferative indices. These included the mitotic count per 50 high power fields (HPFs), the immunohistochemical Ki- 67 labeling index and the immunohistochemical PHH3 mitotic index (MI). For comparison, Spearman’s rank correlation and interclass correlation coefficient were used.Results:Mitotic counts ranged from 0–138 (mean, 7.57±2.34) and the PHH3 MI ranged from 0–126 per 50 HPFs (mean, 9.61±2.27). We found a positive correlation between mitotic counts and PHH3 MI (r=0.810, p<.001). The inter-observer correlation coefficient for three participants was 0.975 for mitotic counts and 0.940 for the PHH3 MI. When using the PHH3 MI instead of mitotic counts in the Armed Forces Institute of Pathology (AFIP) stratification criteria, 10 cases were reclassified. In one patient with a mitotic count of 2 and a PHH3 MI of 6 per 50 HPFs, distant metastasis occurred.Conclusions:In GISTs, the PHH3 MI correlated adequately with mitotic counts and can be used as a useful adjunctive to count mitotic figures efficiently.

Anoctamin 1 induces calcium-activated chloride secretion and proliferation of renal cyst–forming epithelial cells

Polycystic kidney diseases are characterized by multiple bilateral renal cysts that gradually enlarge and lead to a decline in renal function. Cyst enlargement is driven by transepithelial chloride secretion, stimulated by enhanced levels of cyclic adenosine monophosphate, which activates apical cystic fibrosis transmembrane conductance regulator chloride channels. However, chloride secretion by calcium-dependent chloride channels, activated through stimulation of purinergic receptors, also has a major impact. To identify the molecular basis of calcium-dependent chloride secretion in cyst expansion, we determined the role of anoctamin 1 and 6, two recently discovered calcium-activated chloride channels both of which are expressed in epithelial cells. We found that anoctamin 1, which plays a role in epithelial fluid secretion and proliferation, is strongly expressed in principal-like MDCK cells (PLCs) forming cysts within a collagen matrix, in an embryonic kidney cyst model, and in human autosomal dominant polycystic kidney disease tissue. Knockdown of anoctamin 1 but not anoctamin 6 strongly diminished the calcium-dependent chloride secretion of PLCs. Moreover, two inhibitors of anoctamin ion channels, tannic acid and a more selective inhibitor of anoctamin 1, significantly inhibited PLC cyst growth and cyst enlargement in an embryonic kidney cyst model. Knockdown of ANO1 by morpholino analogs also attenuated embryonic cyst growth. Thus, calcium-activated chloride secretion by anoctamin 1 appears to be a crucial component of renal cyst growth.

High expression of the RNA-binding protein RBPMS2 in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract and are often associated with KIT or PDGFRA gene mutations. GIST cells might arise from the interstitial cells of Cajal (ICCs) or from a mesenchymal precursor that is common to ICCs and smooth muscle cells (SMCs). Here, we analyzed the mRNA and protein expression of RNA-Binding Protein with Multiple Splicing-2 (RBPMS2), an early marker of gastrointestinal SMC precursors, in human GISTs (n=23) by in situ hybridization, quantitative RT-PCR analysis and immunohistochemistry. The mean RBPMS2 mRNA level in GISTs was 42-fold higher than in control gastrointestinal samples (p<0.001). RBPMS2 expression was not correlated with KIT and PDGFRA expression levels, but was higher in GISTs harboring KIT mutations than in tumors with wild type KIT and PDGFRA or in GISTs with PDGFRA mutations that were characterized by the lowest RBPMS2 levels. Moreover, RBPMS2 levels were 64-fold higher in GIST samples with high risk of aggressive behavior than in adult control gastrointestinal samples and 6.2-fold higher in high risk than in low risk GIST specimens. RBPMS2 protein level was high in 87% of the studied GISTs independently of their histological classification. Finally, by inhibiting the KIT signaling pathway in GIST882 cells, we show that RBPMS2 expression is independent of KIT activation. In conclusion, RBPMS2 is up-regulated in GISTs compared to normal adult gastrointestinal tissues, indicating that RBPMS2 might represent a new diagnostic marker for GISTs and a potential target for cancer therapy.

Anti-tumor effects of the Notch pathway in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are driven by gain-of-function mutations of KIT or PDGFRa. The introduction of imatinib has significantly extended survival for patients. However, most patients develop resistances. Notch signaling is a conserved developmental pathway known to play a critical role in the development of several cancers, functioning as a tumor promoter or a tumor suppressor. Given that the normal progenitor cell for GIST, the interstitial cell of Cajal, has characteristics similar to those of cells of neuroendocrine origin, we hypothesized that Notch pathway impacts the biology of GIST cells. In this study, we retrovirally and pharmacologically manipulated the Notch pathway in human GIST cells. We also performed a retrospective analysis of a cohort on 15 primary tumors to determine the role of Hes1, a major target gene of Notch, as a prognostic marker for GIST. Constitutively, active intracellular domain of Notch1 (ICN1) expression potently induced growth arrest and downregulated KIT expression in vitro. Additionally, treatment with the histone deacetylase inhibitor suberoylanilide hydroxamic acid caused dose-dependent upregulation of Notch1 expression and a parallel decrease in viability in these cells. Retroviral silencing of downstream targets of Notch (dominant-negative Hes1) and pharmacological inhibition of Notch activation (γ-secretase inhibition) partially rescued GIST cells from suberoylanilide hydroxamic acid treatment. GIST patients with high Hes1 mRNA levels have a significantly longer relapse-free survival. These results identify a novel anti-tumor effect of Notch1 and cross talk between the Notch and KIT pathways. Thus, activation of this pathway by treatment with histone deacetylase inhibitors is an appealing potential therapeutic strategy for GISTs. Précis: This study is the first report of the tumor suppressor effects of Notch pathway in gastrointestinal stromal tumors via a negative feedback with the oncogene KIT and may lead the development of new therapeutic strategies for GISTs patients.

DOG1 (Clone K9) is Seldom Expressed and Not Useful in the Evaluation of Pancreatic Neoplasms

DOG1, a transmembrane calcium-regulated chloride channel protein, is a sensitive and specific marker for gastrointestinal stromal tumors compared with other spindle cell and epithelioid neoplasms. Overexpression has also been described in a variety of both benign and malignant epithelial neoplasms. Recently, DOG1 immunoreactivity has been reported in pancreatic solid pseudopapillary tumors (SPT), suggesting a role as a marker for SPT. Utilizing immunohistochemistry, we evaluated DOG1 expression in pancreatic neoplasms to determine the prevalence of staining and establish diagnostic utility. Multiple tissue microarrays (TMA) were created from cores of formalin-fixed paraffin-embedded blocks containing pancreatic adenocarcinomas (n=112), neuroendocrine tumors (n=99), serous cystadenomas (n=28), and SPT (n=14) as well as normal pancreas (n=12). Immunoreactivity for DOG1 (clone K9) was assessed for intensity (1 to 3+), percentage of tumor positivity and location. Of the 99 cases of neuroendocrine tumors, only 2 (2%) were focally positive. Patchy staining was identified in 8 cases (7%) of adenocarcinoma of 1 to 2+ intensity, involving 15% to 80% of the tumor cells and primarily seen in a membranous and luminal distribution. In contrast to a previous report, no DOG1 positivity was observed in SPT, evaluated by both TMA and full sections. The TMAs of serous cystadenomas and normal pancreas were negative for DOG1. Rarely, pancreatic islets displayed granular, cytoplasmic staining. DOG1 antibody clone K9 is not a useful marker for SPT or other primary pancreatic neoplasms. Additional studies may be helpful to evaluate differences between clones of DOG1.

Thymosin β4 is a novel potential prognostic marker in gastrointestinal stromal tumors

Thymosin beta-4 (Tβ(4)) is a major actin-sequestering molecule that contributes to cell growth, differentiation, motility, survival, mitosis and angiogenesis. It is overexpressed in certain type of carcinoma and fibrosarcoma cell lines and is associated with metastatic potential. The aim of this study was to investigate the relationship between Tβ(4) expression and clinicopathologic features and VEGF status in gastrointestinal stromal tumors (GISTs). Retrospectively, 60 GISTs were re-examined and immunohistochemistry for Tβ(4) and VEGF was performed. Increased expression of Tβ(4) and VEGF was observed in 26 (43.3%) and in 19 (31.6%) of the tumors, respectively. Tβ(4) expression was positively correlated with VEGF expression (p < 0.01). Tβ(4) and VEGF expression were significantly associated with tumor size (p = 0.00 and p = 0.02, respectively) and high mitosis (p = 0.03 and p = 0.00, respectively). Although Tβ(4) expression was positively associated with pleomorphism (p = 0.01), VEGF expression was positively associated with necrosis (p = 0.03). Tβ(4) expression was related with local recurrence and/or metastasis (p = 0.03), but VEGF expression was not (p = 0.12). We firstly demonstrate the presence of Tβ(4) protein in GISTs. Our study reveals that increased expression of Tβ(4) could be considered as an indicator of aggressive behavior of tumor.

Cathepsin L is highly expressed in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors of the gastrointestinal tract that are diagnosed by c-kit staining in most cases. A lysosomal cysteine proteinase termed cathepsin L has been commonly associated with malignancy in several cancer types, but this finding has not been reported for GISTs. We analyzed the cathepsin L mRNA and protein expression in GISTs. Real-time reverse transcription polymerase chain reaction (RT-PCR) analysis revealed that cathepsin L levels were higher in GISTs than those in gastric or colorectal tumors; this finding was supported by results of the Western blot analysis. Immunohistochemistry revealed that cathepsin L was localized to the cytoplasm of GIST cells as an intense granular signal, which was not observed in the cells of leiomyoma, a mesenchymal tumor that was analyzed as a control specimen. Double immunofluorescence microscopy revealed that a portion of the granular signal colocalized with lysosome-associated membrane protein-1 (LAMP-1), which is a lysosomal marker. Moreover, immunohistochemical analysis of 43 tumor specimens revealed that 86.0% (n=37) were cathepsin-L positive, and this positivity was significantly correlated with c-kit positivity but not with other clinicopathological factors, including gender, age, region, size, mitosis and risk of recurrence. From these results, we conclude that cathepsin L is highly expressed in GISTs compared to its expression in other cancerous lesions; this identifies cathepsin-L as a new diagnostic marker for GISTs.

Gastrointestinal Stromal Tumors: Disease and Treatment Update

Gastrointestinal Stromal Tumors: Disease and Treatment Update