DOG1 and PKC-θ are useful in the diagnosis of KIT-negative gastrointestinal stromal tumors

Clinicopathological and immunohistochemical characterization of gastrointestinal stromal tumour at four tertiary health centers in Nigeria using CD117, DOG1, and human epidermal growth factor receptor-2 biomarkers

Aims

Gastrointestinal stromal tumors (GISTs) are neoplastic lesions that primarily affect the digestive tract and develop from interstitial cells of Cajal. These lesions require histopathological and immunohistochemical characterization due to their malignant potential and personalized treatment. In this investigation, the sex, age, lesional sites of origin, histopathological types, the prevalence of human epidermal growth factor receptors (HER-2) expression, prognostic indices (based on tumor size and mitotic figures), expression of CD117 and DOG1, and characteristics of patients with GIST were all characterized.

Materials and Methods

This was a retrospective cross-sectional analysis of GIST cases seen at four tertiary health-care centers in Nigeria over a 10-year period (2008-2017) and investigated utilizing histopathological and immunohistochemical (CD117, DOG1, and HER-2) methods.

Results

In this investigation, there were twenty GIST cases. Notably, the majority (40%) of the cases had tumors with sizes between 7.0 and 8.0 cm; the stomach was the most frequent site (70%) and the spindle cell type of GIST was the most prevalent (80%) histopathological type. In addition, the stomach was significantly associated with GIST as an origin site (with a P = 0.001), and 100% and 50% of these tumors were immunoreactive with CD117 and DOG1, respectively.

Conclusions

In our study, GISTs most frequently develop in the stomach, and CD117 and DOG1 are essential for correctly diagnosing these tumors. However, HER-2 immunoreactivity is a predictive marker of survival for personalized care.

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.

Protein Kinase C (PKC) Isozymes as Diagnostic and Prognostic Biomarkers and Therapeutic Targets for Cancer

Protein kinase C (PKC) is a large family of calcium- and phospholipid-dependent serine/threonine kinases that consists of at least 11 isozymes. Based on their structural characteristics and mode of activation, the PKC family is classified into three subfamilies: conventional or classic (cPKCs; α, βI, βII, and γ), novel or non-classic (nPKCs; δ, ε, η, and θ), and atypical (aPKCs; ζ, ι, and λ) (PKCλ is the mouse homolog of PKCι) PKC isozymes. PKC isozymes play important roles in proliferation, differentiation, survival, migration, invasion, apoptosis, and anticancer drug resistance in cancer cells. Several studies have shown a positive relationship between PKC isozymes and poor disease-free survival, poor survival following anticancer drug treatment, and increased recurrence. Furthermore, a higher level of PKC activation has been reported in cancer tissues compared to that in normal tissues. These data suggest that PKC isozymes represent potential diagnostic and prognostic biomarkers and therapeutic targets for cancer. This review summarizes the current knowledge and discusses the potential of PKC isozymes as biomarkers in the diagnosis, prognosis, and treatment of cancers.

Risk Factors and Prognostic Analysis of Gastrointestinal Stromal Tumor Recurrence-Metastasis

Objective

Gastrointestinal stromal tumors (GISTs) are potential malignancies that occur in the digestive tract. This study aimed to investigate the risk factors and prognosis of recurrence and metastasis of gastrointestinal stromal tumor (GIST).

Methods

From January 2018 to December 2019, 422 patients with GIST who received surgery in the First Affiliated Hospital of Wenzhou Medical University were enrolled. Their clinical data were retrospectively analyzed, and their follow-ups were continued until March 31, 2022. Subsequently, univariate and multivariate Cox analyses, survival curves, and nomograms were adopted to explore the relationship between clinicopathological characteristics and recurrence or metastasis in patients with GIST.

Results

Univariate and multivariate Cox analysis exhibited that the prognosis of patients was affected by tumor rupture (P = 0.040), tumor location (P < 0.001), tumor diameter (P = 0.016), mitotic figures (P < 0.001), and risk grade (P < 0.009). The above variables were selected to create the nomogram for 3-year disease-free survival (DFS). The 3-year the ROC (receiver operating characteristic) curves of the nomogram were (0.878 95% confidence interval [CI]: 0.871-0.939).

Conclusion

Collectively, risk factors affecting postoperative recurrence or metastasis of GIST consist of primary site of tumors, tumor rupture, tumor diameter >10 cm, high-risk tumor classification, and mitotic figures ≥10 per 50 HPFs. And the application of nomogram may help physicians provide individualized diagnosis and treatment for patients with GISTs following surgical resection.

Cecal gastrointestinal stromal tumor causing ileocolic intussusception in an adult: A rare case report

Introduction and importance

Cecal gastrointestinal stromal tumors (GIST) constitute a rarer subtype of all GISTs. Rarely, it can present with ileocolic intussusception in adults making it a challenging diagnosis due to non-specific clinical features.

Case presentation

A 30-year previously healthy woman presented with lower abdominal pain and a distended abdomen who was subsequently diagnosed with ileocolic intussusception on a CT scan. Intraoperatively, a pedunculated polypoid hard mass was identified in the cecum and thus, a standard right hemicolectomy was performed with the suspicion of malignancy. Histopathology of the resected mass confirmed CD117 negative, spindle type GIST.

Discussion

Cecal GIST presenting in the form of ileocolic intussusception is rare. Contrast-enhanced CT scan is the preferred imaging modality for the evaluation of patients with suspected GIST to determine the extent of the tumor, the presence or absence of metastatic disease alongside evaluation of the possibility of complete resection. Adjuvant imatinib therapy following complete resection decreases the disease recurrence.

Conclusion

Intussusception in an adult can be the first manifestation of underlying malignancy like GIST. Complete surgical resection of the tumor with a negative margin offers long-term survival.

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Ileocolic intussusception is rare in adult and often associated with pathological lead points like neoplasm.

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Cecal GIST is an uncommon cause of ileocolic intussusception in adults.

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Diagnosis of this entity is challenging because of its non-specific presenting features.

Gastrointestinal stromal tumor: a review of current and emerging therapies

Gastrointestinal stromal tumors (GIST) are rare neoplasms arising from the interstitial cell of Cajal in the gastrointestinal tract. Two thirds of GIST in adult patients have c-Kit mutation and smaller fractions have platelet derived growth factor receptor alpha (PDGFRA) mutation. Surgery is the only curative treatment for localized disease. Imatinib improves survival when used adjuvantly and in advanced disease. Several targeted therapies have also improved survival in GIST patients after progression on imatinib including sunitinib and regorafenib. Recently, United States Federal and Drug Administration (FDA) approved two new tyrosine kinase inhibitors for the treatment of heavily pretreated advanced/unresectable GIST including avapritinib (a selective inhibitor for PDGFRA exon 18 mutation including D842V mutations) and ripretinib (a broad-spectrum kinase inhibitor of c-Kit and PDGFRA). In this article, we will provide a comprehensive review of GIST including the current standard of care treatment and exploring future paradigm shifts in therapy.

Diagnostic Immunohistochemistry of Soft Tissue and Bone Tumors: An Update on Biomarkers That Correlate with Molecular Alterations

The diagnosis of benign and malignant soft tissue and bone neoplasms is a challenging area of surgical pathology, due to the large number, rarity, and histologic diversity of tumor types. In recent years, diagnosis and classification has been aided substantially by our growing understanding of recurrent molecular alterations in these neoplasms. Concurrently, the role of diagnostic immunohistochemistry has also expanded, with the development of numerous biomarkers based on underlying molecular events. Such biomarkers allow us to infer the presence of these events and can therefore substitute for other ancillary molecular genetic techniques (e.g., fluorescence in situ hybridization, polymerase chain reaction, and next-generation sequencing). In this review, we discuss a range of biomarkers currently available for these neoplasms, highlighting the accuracy, staining characteristics, and interpretation pitfalls of each antibody. These include immunohistochemical antibodies that represent reliable surrogates for the detection of gene fusions (e.g., STAT6, CAMTA1, FOSB, DDIT3) and more recently described breakpoint-specific antibodies (e.g., SS18-SSX, PAX3/7-FOXO1). Additionally, discussed are markers that correlate with the presence of gene amplifications (e.g., MDM2, CDK4), deletions (e.g., SMARCB1, SMARCA4), single nucleotide variants (e.g., G34W, K36M), aberrant methylation (H3K27me3), and increased expression as discovered through gene expression profiling (e.g., MUC4, DOG1, ETV4, NKX2.2, NKX3.1).

Clinical Diagnosis of Gastrointestinal Stromal Tumor (GIST): From the Molecular Genetic Point of View

Gastrointestinal stromal tumors (GISTs) originating from the interstitial cells of Cajal are mesenchymal tumors of the gastrointestinal tract and have been found to harbor c-KIT mutations and KIT (CD117) expression since 1998. Later, PDGFRA mutations, SDH alterations, and other drive mutations were identified in GISTs. In addition, more and more protein markers such as DOG1, PKCθ were found to be expressed in GISTs which might help clinicians diagnose CD117-negative GISTs. Therefore, we plan to comprehensively review the molecular markers and genetics of GISTs and provide clinicians useful information in diagnostic and therapeutic strategies of GISTs. Twenty years after the discovery of KIT in GISTs, the diagnosis of GISTs became much more accurate by using immunohistochemical (IHC) panel (CD117/DOG1) and molecular analysis (KIT/PDGFRA), both of which constitute the gold standard of diagnosis in GISTs. The accurately molecular diagnosis of GISTs guides clinicians to precision medicine and provides optimal treatment for the patients with GISTs. Successful treatment in GISTs prolongs the survival of GIST patients and causes GISTs to become a chronic disease. In the future, the development of effective treatment for GISTs resistant to imatinib/sunitinib/regorafenib and KIT/PDGFRA-WT GISTs will be the challenge for GISTs.

Contribution of Anoctamins to Cell Survival and Cell Death

Before anoctamins (TMEM16 proteins) were identified as a family of Ca2+-activated chloride channels and phospholipid scramblases, the founding member anoctamin 1 (ANO1, TMEM16A) was known as DOG1, a marker protein for gastrointestinal stromal tumors (GIST). Meanwhile, ANO1 has been examined in more detail, and the role of ANO1 in cell proliferation and the development of different types of malignomas is now well established. While ANO5, ANO7, and ANO9 may also be relevant for growth of cancers, evidence has been provided for a role of ANO6 (TMEM16F) in regulated cell death. The cellular mechanisms by which anoctamins control cell proliferation and cell death, respectively, are just emerging; however, the pronounced effects of anoctamins on intracellular Ca2+ levels are likely to play a significant role. Recent results suggest that some anoctamins control membrane exocytosis by setting Ca2+i levels near the plasma membrane, and/or by controlling the intracellular Cl- concentration. Exocytosis and increased membrane trafficking induced by ANO1 and ANO6 may enhance membrane expression of other chloride channels, such as CFTR and volume activated chloride channels (VRAC). Notably, ANO6-induced phospholipid scrambling with exposure of phosphatidylserine is pivotal for the sheddase function of disintegrin and metalloproteinase (ADAM). This may support cell death and tumorigenic activity of IL-6 by inducing IL-6 trans-signaling. The reported anticancer effects of the anthelminthic drug niclosamide are probably related to the potent inhibitory effect on ANO1, apart from inducing cell cycle arrest through the Let-7d/CDC34 axis. On the contrary, pronounced activation of ANO6 due to a large increase in intracellular calcium, activation of phospholipase A2 or lipid peroxidation, can lead to ferroptotic death of cancer cells. It therefore appears reasonable to search for both inhibitors and potent activators of TMEM16 in order to interfere with cancer growth and metastasis.

Differential expression of PKCα and -β in the zebrafish retina

The retina is a complex neural circuit, which processes and transmits visual information from light perceiving photoreceptors to projecting retinal ganglion cells. Much of the computational power of the retina rests on signal integrating interneurons, such as bipolar cells. Commercially available antibodies against bovine and human conventional protein kinase C (PKC) α and -β are frequently used as markers for retinal ON-bipolar cells in different species, despite the fact that it is not known which bipolar cell subtype(s) they actually label. In zebrafish (Danio rerio) five prkc genes (coding for PKC proteins) have been identified. Their expression has not been systematically determined. While prkcg is not expressed in retinal tissue, the other four prkc (prkcaa, prkcab, prkcba, prkcbb) transcripts were found in different parts of the inner nuclear layer and some as well in the retinal ganglion cell layer. Immunohistochemical analysis in adult zebrafish retina using fluorescent in situ hybridization and PKC antibodies showed an overlapping immunolabeling of ON-bipolar cells that are most likely of the BON s6 and BON s6L or RRod type. However, comparison of transcript expression with immunolabeling, implies that these antibodies are not specific for one single zebrafish conventional PKC, but rather detect a combination of PKC -α and -β variants.

Tumor rupture of gastric gastrointestinal stromal tumors during endoscopic resection: a risk factor for peritoneal metastasis?

BACKGROUND AND STUDY AIMS

 Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the gastrointestinal tract. Up to the present time, complete surgical excision has been the standard treatment for primary GISTs greater than 2 cm. It is well known that tumor rupture during surgery is an independent risk factor for peritoneal metastasis; however, it is not known whether the risk of peritoneal metastasis increases in cases where the tumor is ruptured during endoscopic resection.

PATIENTS AND METHODS

 A total of 195 patients treated for GIST between January 2014 and December 2016 in our hospital were enrolled in this study. They were divided into two groups according to whether the tumor was ruptured during endoscopic resection. The rate of peritoneal metastasis in patients in the two groups who also suffered perforation was investigated from the follow-up results.

RESULTS

 Approximately 55.4 % of all patients were female and the average age of the study group was 59.0 ± 10.3 years. Of the 195 patients, the tumors in 27 were ruptured and the remaining 168 patients underwent en bloc resection. There was no statistically significant difference in gender or age between the two groups. The median tumor size (maximum diameter) in all patients was 1.5 cm (0.3 - 5.0 cm): 2.5 cm (0.8 - 5.0 cm) and 1.4 cm (0.3 - 4.0 cm) in the tumor rupture group and en bloc resection group, respectively ( P  < 0.001). Most of the tumors were located in the gastric fundus. At a median follow-up of 18.7 ± 10.2 months, neither tumor recurrence (liver metastasis, peritoneal metastasis, local recurrence) nor mortality related to GISTs were detected.

CONCLUSIONS

 Tumor rupture during endoscopic resection of gastric GISTs may not be a risk factor for peritoneal metastasis.

Gastrointestinal stromal tumors: A multidisciplinary challenge

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors located in the alimentary tract. Its usual manifestation is gastrointestinal bleeding. However, small asymptomatic lesions are frequently detected as incidental finding. Characteristically, most GISTs (> 95%) are positive for the KIT protein (CD117) by IHC staining and approximately 80%-90% of GISTs carry a mutation in the c-KIT or PDGFRA genes. Mutational analysis should be performed when planning adjuvant and neoadjuvant therapy, due to its possible resistance to conventional treatment. The arise of tyrosine kinase inhibitor has supposed a revolution in GISTs treatment being useful as adjuvant, neoadjuvant or recurrence disease treatment. That is why a multidisciplinary approach to this disease is required. The correct characterization of the tumor at diagnosis (the diagnosis of recurrences and the evaluation of the response to treatment with tyrosine kinase inhibitors) is fundamental for facing these tumors and requires specialized Endoscopist, Radiologists and Nuclear Medicine Physician. Surgery is the only potentially curative treatment for suspected resectable GIST. In the case of high risk GISTs, surgery plus adjuvant Imatinib-Mesylate for 3 years is the standard treatment. Neoadjuvant imatinib-mesylate should be considered to shrink the tumor in case of locally advanced primary or recurrence disease, unresectable or potentially resectable metastasic tumors, and potentially resectable disease in complex anatomic locations to decrease the related morbidity. In the case of Metastatic GIST under Neoadjuvant treatment, when there are complete response, stable disease or limited disease progression, complete cytoreductive surgery could be a therapeutic option if feasible.

Gastrointestinal stromal tumor of the esophagus: current issues of diagnosis, surgery and drug therapy

Gastrointestinal stromal tumors (GISTs) often arise in the stomach and small intestine, while esophageal GISTs are rare. Due to their rarity, clinicopathological data on esophageal GISTs are extremely limited, and this results in a lack of clear recommendations concerning optimal surgical management for esophageal GISTs. It is difficult to distinguish esophageal GIST from leiomyoma, the most frequent esophageal mesenchymal tumor, prior to resection, because the two types of tumors appear similar on computed tomography (CT), endoscopic ultrasound (EUS), and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET). Fine-needle aspiration biopsy (FNAB) under EUS enables definitive diagnosis, but it is often avoided because scarring could make enucleation more difficult and increase the risk of tumor dissemination by capsule destruction. Esophageal segmental and wedge resections are not usually performed due to the anatomical peculiarity of the esophagus, and the surgical options are limited to the highly invasive esophagectomy or the much less invasive surgical tumor enucleation. The decision as to which surgical procedure should be performed for esophageal GISTs is still under debate. Tumor enucleation may be permitted for smaller tumors, and esophagectomy may be recommended for larger GISTs or high-risk tumors with a high mitotic rate. The purpose of neoadjuvant imatinib administration is downsizing of the GIST to reduce the extent of resection and to reduce the risk of intraoperative complications, including tumor rupture. The efficacy of neoadjuvant/adjuvant imatinib therapy for esophageal GISTs is poorly understood, because the reports are limited to case reports or case series with small numbers. More clinicopathological data and clinical trials for esophageal GIST are expected.

Tyrosine kinase inhibitor sensitive PDGFRΑ mutations in GIST: Two cases and review of the literature

Gastrointestinal stromal tumors (GISTs) are rare mesenchymal malignancies of the gastrointestinal tract. Most GISTs harbor a c-KIT (80%) or a PDGFRα (10%) mutation that leads to constitutive activation of the tyrosine kinase receptor. Response to treatment with tyrosine kinase inhibitors (TKIs) is dependent on mutational status of the tumor. The most common mutation in PDGFRα, D842V, is known to be imatinib resistant. Almost all other PDGFRα mutations are imatinib sensitive. We describe two patients with a PDGFRα exon 18 mutated GIST responding to treatment with TKIs. One of these patients has a p.M844_S847 deletion, not previously described in relation with TKI treatment response. Mutations in circulating tumor DNA were detectable with digital droplet PCR in serial plasma samples taken during treatment and correlated with treatment response of both patients. Computer 3D-modeling of the PDGFRα kinase domain of these two variants revealed no direct interference in imatinib or sunitinib binding and no effect in its activity in contrast to the reported structure of the imatinib resistant D842V mutation.

An overview is given of the literature regarding the evidence of patients with different PDGFRα mutated GISTs on response to TKIs. The findings emphasize the use of mutational analysis in GIST to provide patients personalized treatment. Detection of mutations in plasma is feasible and can provide real-time information concerning treatment response. We suggest to register GIST patients with these uncommon mutations in a prospective international database to understand the tumor biology and obtain more evidence of such mutations to predict treatment response.

Surgical Pathology of Gastrointestinal Stromal Tumors: Practical Implications of Morphologic and Molecular Heterogeneity for Precision Medicine

Gastrointestinal stromal tumor (GIST), the most common mesenchymal neoplasm of the gastrointestinal tract, exhibits diverse histologic and clinical manifestations. With its putative origin in the gastrointestinal pacemaker cell of Cajal, GIST can arise in association with any portion of the tubular gastrointestinal tract. Morphologically, GISTs are classified as spindled or epithelioid, though each of these subtypes encompasses a broad spectrum of microscopic appearances, many of which mimic other histologic entities. Despite this morphologic ambiguity, the diagnosis of GIST is aided in many cases by immunohistochemical detection of KIT (CD117) or DOG1 expression. The natural history of GIST ranges from that of a tumor cured by surgical resection to that of a locally advanced or even widely metastatic, and ultimately fatal, disease. This clinicopathologic heterogeneity is paralleled by an underlying molecular diversity: the majority of GISTs are associated with spontaneous activating mutations in KIT, PDGFRA, or BRAF, while additional subsets are driven by genetic lesions-often inherited-of NF1 or components of the succinate dehydrogenase enzymatic complex. Specific gene mutations correlate with particular anatomic or morphologic characteristics and, in turn, with distinct clinical behaviors. Therefore, prognostication and treatment are increasingly dictated not only by morphologic clues, but also by accompanying molecular genetic features. In this review, we provide a comprehensive description of the heterogenous molecular underpinnings of GIST, including implications for the practicing pathologist with regard to morphologic identification, immunohistochemical diagnosis, and clinical management.

Practical Immunohistochemistry in Neoplastic Pathology of the Gastrointestinal Tract, Liver, Biliary Tract, and Pancreas

CONTEXT

- Immunomarkers with diagnostic, therapeutic, or prognostic values have been increasingly used to maximize the benefits of clinical management of patients with neoplastic diseases of the gastrointestinal tract, liver, biliary tract, and pancreas.

OBJECTIVES

- To review the characteristics of immunomarkers that are commonly used in surgical pathology practice for neoplasms of the gastrointestinal tract, liver, biliary tract, and pancreas, and to summarize the clinical usefulness of immunomarkers that have been discovered in recent years in these fields.

DATA SOURCES

- Data sources include literature review, authors' research data, and personal practice experience.

CONCLUSIONS

- Immunohistochemistry is an indispensable tool for the accurate diagnosis of neoplastic diseases of the gastrointestinal tract, liver, biliary tract, and pancreas. Useful immunomarkers are available to help distinguish malignant neoplasms from benign conditions, determine organ origins, and subclassify neoplasms that are morphologically and biologically heterogeneous. Specific immunomarkers are also available to help guide patient treatment and assess disease aggressiveness, which are keys to the success of personalized medicine. Pathologists will continue to play a critical role in the discovery, validation, and application of new biomarkers, which will ultimately improve patient care.

Gastrointestinal stromal tumours of the oesophagus: a clinicopathological and molecular analysis of 27 cases

AIMS

Gastrointestinal stromal tumours (GISTs) may arise anywhere in the gastrointestinal tract, but are rare in the oesophagus. We describe the clinical, pathological and molecular characteristics of 27 primary oesophageal GISTs, the largest series to date.

METHODS AND RESULTS

DNA was extracted and exons 9, 11, 13 and 17 of KIT, exons 12, 14 and 18 of PDGFRA and exon 15 of BRAF were amplified and sequenced. Oesophageal GISTs occurred in 14 men and 13 women aged between 22 and 80 years (mean: 56 years). All 27 cases were immunohistochemically positive for KIT, and 92 and 47% co-expressed CD34 or smooth muscle actin, respectively. Fifteen (71% of analysed cases) harboured KIT exon 11 mutations and one case each had a mutation in KIT exon 13 (K642E) or BRAF exon 15 (V600E). Long-term follow-up data (median, 96.5 months) were obtained for 20 cases; two patients had metastases at presentation and seven had developed local recurrence and/or metastasis after surgery. A large tumour size (≥ 10 cm), high mitotic rate (> 5/5 mm² ), presence of a deletion mutation in KIT exon 11 involving codons 557-558 and a positive microscopic margin were associated with recurrence and metastasis. The KIT mutations identified in oesophageal GISTs are similar to those observed in gastric GISTs.

CONCLUSIONS

Complete surgical resection with clear margins is recommended, if technically feasible, and genotyping can help to improve diagnosis and further patient management in oesophageal GIST.

PKCθ utility in diagnosing c-KIT/DOG-1 double negative gastrointestinal stromal tumors

BACKGROUND

The aim of this study was to evaluate the diagnosis value of an immunohistochemical (IHC) panel of three antibodies for the diagnosis of gastrointestinal stromal tumors (GISTs).

MATERIAL AND METHODS

In 80 consecutive GISTs without lymph node metastases, the IHC examinations were performed using the antibodies CD117 (c-KIT), DOG-1 and c-theta (PKCθ) protein. The diagnostic value of PKCθ in c-KIT/DOG-1 negative GISTs has been explored in fewer than 10 Medline-indexed papers.

RESULTS

The c-KIT, PKCθ and DOG-1 positivity was noted in 92.50% (n = 74), 90% (n = 72) and 76.25% (n = 61) of the cases, respectively. All of the C-KIT negative cases (n = 6) were also DOG-1 negative but displayed PKCθ positivity. All of the DOG-1 positive cases (n = 61) also expressed c-KIT. No correlation between the examined markers and clinicopathological parameters was noted.

CONCLUSIONS

The PKCθ sensitivity is similar to c-KIT and superior to DOG-1 sensitivity. All of the c-KIT/DOG-1 negative GISTs seem to express PKCθ. For a proper diagnosis of GIST, the c-KIT/DOG-1/PKCθ panel should be used, with possible therapeutic but not prognostic value.

Gastrointestinal stromal tumours (GISTs): an insight into clinical practice with review of literature

BACKGROUND

Gastrointestinal stromal tumours (GISTs) are rare mesenchymal tumours of the gastrointestinal tract. We retrospectively reviewed the clinical management of all patients with GIST presenting to a regional multidisciplinary upper gastrointestinal cancer group in the north of England.

METHODS

Clinical, pathological, immunohistochemical treatment strategies, follow-up and outcome data on all patients with GIST between 2007 and 2012 were reviewed. Tumours were categorised by risk according to the National Institutes of Health (NIH) and AFIP models.

RESULTS

36 (85.7%) of 42 tumours were located in the stomach, 5 (11.9%) in the small intestine and 1 (2.4%) in the oesophagus. Median age of patients was 68 (range 43-91) years. 24 patients (57.1%) were female. Tumour size ranged from 1.0  to 12.7 cm with mean size of 5.46 cm. Metastasis was present in 19 (45.2%) patients at diagnosis with distant metastases in 12 patients. Liver was the most common site of metastases. Histology and immunohistochemical analysis was available in 32 (76.2%) patients. Most common histology was spindle cell morphology 17/32 (53.1%) followed by epithelioid 9/32 (28.1%) and mixed morphology 5/32 (15.6%). The positive rate for KIT protein (CD117) was 90.6%, while that for CD34 was 75.0%. 12/25 (48.0%) and 8/23 (34.8%) patients were categorised as high risk as per NIH and AFIP risk scores, respectively. 23/42 (54.8%) patients underwent surgical resection, after which 5/23 (21.7%) had adjuvant imatinib therapy. Imatinib was given as primary therapy in 14/42 (33.3%) patients.

CONCLUSIONS

Surgery alone may not be a curative treatment for GISTs. Targeted therapy with imatinib may play an important role in the treatment of GISTs. Further risk categorisation models may be needed to evaluate GIST behaviour and prognosis.

Asian Consensus Guidelines for the Diagnosis and Management of Gastrointestinal Stromal Tumor

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors originating in the gastrointestinal tract. With the introduction of molecular-targeted therapy for GISTs which has yielded remarkable outcomes, these tumors have become a model of multidisciplinary oncological treatment. Although Western clinical guidelines are available for GISTs, such as those published by the National Comprehensive Cancer Network (NCCN) and the European Society of Medical Oncology (ESMO), the clinical situations in Asian countries are different from those in Western countries in terms of diagnostic methods, surgical approach, and availability of new targeted agents. Accordingly, we have reviewed current versions of several GIST guidelines published by Asian countries (Japan, Korea, China, and Taiwan) and the NCCN and ESMO and discussed the areas of dissensus. We here present the first version of the Asian GIST consensus guidelines that were prepared through a series of meetings involving multidisciplinary experts in the four countries. These guidelines provide an optimal approach to the diagnosis and management of GIST patients in Asian countries.

C-Kit-Negative Gastrointestinal Stromal Tumor in the Stomach

C-kit-negative gastrointestinal stromal tumors (GISTs) are uncommon, and there have been few reports about the diagnosis and treatment of c-kit-negative GISTs in the stomach. We report the case of a patient who was diagnosed with a huge and atypical GIST in the stomach. The GIST was completely resected and finally diagnosed as c-kit-negative GIST based on immunohistochemical staining of tumor cells, which were negative for CD117 and CD34 and positive for Discovered on GIST-1 (DOG1). C-kit-negative GISTs could be treated by complete resection and/or imatinib, which is the same treatment for c-kit-positive GISTs.

ETV1 mRNA is specifically expressed in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) develop from interstitial cells of Cajal (ICCs) mainly by activating mutations in the KIT or PDGFRA genes. Immunohistochemical analysis for KIT, DOG1, and PKC-θ is used for the diagnosis of GIST. Recently, ETV1 has been shown to be a lineage survival factor for ICCs and required for tumorigenesis of GIST. We investigated the diagnostic value of ETV1expression in GIST. On fresh-frozen tissue samples, RT-PCR analysis showed that ETV1 as well as KIT, DOG1, and PKC-θ are highly expressed in GISTs. On tissue microarrays containing 407 GISTs and 120 non-GIST mesenchymal tumors of GI tract, we performed RNA in situ hybridization (ISH) for ETV1 together with immunohistochemical analysis for KIT, DOG1, PKC-θ, CD133, and CD44. Overall, 387 (95 %) of GISTs were positive for ETV1, while KIT and DOG1 were positive in 381 (94 %) and 392 (96 %) cases, respectively, showing nearly identical overall sensitivity of ETV1, KIT, and DOG1 for GISTs. In addition, ETV1 expression was positively correlated with that of KIT. Notably, ETV1 was positive in 15 of 26 (58 %) KIT-negative GISTs and even positive in 2 cases of GIST negative for KIT and DOG1, whereas only 6 (5 %) non-GIST mesenchymal GI tumors expressed ETV1. We conclude that ETV1 is specifically expressed in the majority of GISTs, even in some KIT-negative cases, suggesting that ETV1 may be useful as ancillary marker in diagnostically difficult select cases of GIST.

Expression of CD117, DOG-1, and IGF-1R in gastrointestinal stromal tumours - an analysis of 70 cases from 2004 to 2010

Introduction

Determination of the type of mutations in gastrointestinal stromal tumours (GIST) plays a major role in assessing the risk of progression of the disease, and also allows determination of the clinical management and treatment. More accurate GIST diagnosis is possible by using simultaneously various types of antibodies to immunohistochemistry methods in routine procedures.

Aim

To evaluate the expression of CD117, DOG-1, and IGF-1R in patients with gastrointestinal stromal tumours, and analysis of the impact of the examined protein expression on patient survival with emphasis on specific recognition and prognostication of these tumours.

Material and methods

The protein expression was analyzed in 70 patients who had undergone surgical treatment for mesenchymal tumours of the gastrointestinal tract, using the immunohistochemical method.

Results

Positive expression of CD117, DOG-1, and IGF1R included 95.71%, 88.57% and 11.43% of study GISTs, respectively. Statistical analysis showed positive significant correlation between DOG-1 expression and histological type of tumour (p = 0.024). Analysis of overall survival curves of 70 GIST patients according to expression of CD117, DOG-1, and IGF1R did not show a tendency towards longer survival of patients with positive expression (p > 0.05).

Conclusions

Predictive factors determining the survival time of patients are strongly associated with morphological features of tumours. A thorough analysis of each case plays a key role in predicting survival time of patients and may be a clue in targeting the therapeutic procedure.

The Novel PKCθ from Benchtop to Clinic

The protein kinases C (PKCs) are a family of serine/threonine kinases involved in regulating multiple essential cellular processes such as survival, proliferation, and differentiation. Of particular interest is the novel, calcium-independent PKCθ which plays a central role in immune responses. PKCθ shares structural similarities with other PKC family members, mainly consisting of an N-terminal regulatory domain and a C-terminal catalytic domain tethered by a hinge region. This isozyme, however, is unique in that it translocates to the immunological synapse between a T cell and an antigen-presenting cell (APC) upon T cell receptor-peptide MHC recognition. Thereafter, PKCθ interacts physically and functionally with downstream effectors to mediate T cell activation and differentiation, subsequently leading to inflammation. PKCθ-specific perturbations have been identified in several diseases, most notably autoimmune disorders, and hence the modulation of its activity presents an attractive therapeutic intervention. To that end, many inhibitors of PKCs and PKCθ have been developed and tested in preclinical and clinical studies. And although selectivity remains a challenge, results are promising for the future development of effective PKCθ inhibitors that would greatly advance the treatment of several T-cell mediated diseases.

An update on the application of newly described immunohistochemical markers in soft tissue pathology

CONTEXT

During the last 5 to 10 years, significant progress has been made in the molecular characterization of soft tissue tumors, predominantly with the identification of recurrent translocations or amplification of certain genes in different tumor types. Alongside this, translational efforts have identified many novel and diagnostically useful immunohistochemical markers for many of these tumor types.

OBJECTIVE

This article reviews a select group of recently described immunohistochemical markers of particular use in the evaluation of mesenchymal neoplasms; the underlying biology of the protein product, practical utility, and limitations of each marker are discussed in detail.

DATA SOURCES

Literature review, authors' research data, and personal practice experience serve as sources.

CONCLUSIONS

There are many diagnostically useful immunohistochemical markers to help confirm the diagnosis of many different soft tissue tumor types, some of which have reduced the need for additional, and more costly, studies, such as fluorescence in situ hybridization. However, no one marker is 100% specific for a given tumor, and knowledge of potential pitfalls and overlap in patterns of staining among other tumor types is crucial to ensure the appropriate application of these markers in clinical practice.

DOG1 is a sensitive and specific immunohistochemical marker for diagnosis of canine gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) and leiomyosarcomas are histologically similar primary neoplasms commonly occurring in the gastrointestinal tract of dogs and humans. Immunohistochemical staining (IHC) is needed to differentiate between these 2 entities and positive reactivity for KIT (cluster of differentiation [CD]117) is regarded as the gold standard for diagnosis of canine GIST. Studies estimate 5–10% of human GISTs stain negative or only weakly positive for KIT and have identified DOG1 (discovered on gastrointestinal stromal tumors protein 1) as a highly sensitive and specific marker for human GISTs. The purpose of this study was to evaluate immunoreactivity of a commercially available DOG1 antibody for use in diagnosis of canine GISTs. Fifty-five primary mesenchymal gastrointestinal tumors with histologic features consistent with GIST or leiomyosarcoma were evaluated via IHC for KIT, DOG1, and desmin. A subset of tumors was additionally evaluated for reactivity for smooth muscle actin (SMA). Thirty-three tumors (60%) were diagnosed as GIST based on positive immunoreactivity for KIT or DOG1 regardless of reactivity for desmin or SMA. Most GISTs (32/33, 97.0%) had similar staining for both KIT and DOG1. DOG1 expression was identified in 2 tumors (1 study tumor and 1 additional tumor) negative for KIT and desmin that had histologic features consistent with KIT-negative, platelet-derived growth factor receptor-alpha (PDGFRA)-mutant human GISTs. Our results suggest that DOG1 has improved specificity and sensitivity to that of KIT for differentiating between canine GISTs and leiomyosarcomas. Inclusion of both DOG1 and KIT IHC in diagnostic panels will improve the accuracy of canine GIST diagnosis.

Protein kinase C and cancer: what we know and what we do not

Since their discovery in the late 1970s, protein kinase C (PKC) isozymes represent one of the most extensively studied signaling kinases. PKCs signal through multiple pathways and control the expression of genes relevant for cell cycle progression, tumorigenesis and metastatic dissemination. Despite the vast amount of information concerning the mechanisms that control PKC activation and function in cellular models, the relevance of individual PKC isozymes in the progression of human cancer is still a matter of controversy. Although the expression of PKC isozymes is altered in multiple cancer types, the causal relationship between such changes and the initiation and progression of the disease remains poorly defined. Animal models developed in the last years helped to better understand the involvement of individual PKCs in various cancer types and in the context of specific oncogenic alterations. Unraveling the enormous complexity in the mechanisms by which PKC isozymes have an impact on tumorigenesis and metastasis is key for reassessing their potential as pharmacological targets for cancer treatment.

Protein Kinase C (PKC) Isozymes and Cancer

Protein kinase C (PKC) is a family of phospholipid-dependent serine/threonine kinases, which can be further classified into three PKC isozymes subfamilies: conventional or classic, novel or nonclassic, and atypical. PKC isozymes are known to be involved in cell proliferation, survival, invasion, migration, apoptosis, angiogenesis, and drug resistance. Because of their key roles in cell signaling, PKC isozymes also have the potential to be promising therapeutic targets for several diseases, such as cardiovascular diseases, immune and inflammatory diseases, neurological diseases, metabolic disorders, and multiple types of cancer. This review primarily focuses on the activation, mechanism, and function of PKC isozymes during cancer development and progression.

Differential clinical and pathological characteristics of esophageal stromal tumors and leiomyomata

The objective of the study was to assess the differences in clinical and pathological characteristics between esophageal stromal tumor and leiomyoma. Data from 93 esophageal stromal tumors and leiomyomata cases were retrospectively analyzed, including clinical symptoms, endoscopic features, pathological characteristics, immunohistochemistry (IHC), and treatment. All cases underwent endoscopic ultrasonography examination before treatment. Lesions arising from the muscularis mucosa were resected by endoscopic mucosal resection or endoscopic submucosal dissection. Lesions arising from the muscularis propria were resected by surgery. All specimens were examined by IHC. Patients were followed up after endoscopic mucosal resection or endoscopic submucosal dissection. No difference was observed in clinical symptoms and endoscopic features between the two groups. Endoscopic ultrasonography demonstrated all lesions to be hypoechoic and well circumscribed. Most lesions >2 cm had heterogeneous internal ultrasound signal. In esophageal stromal tumor, 100% (29/29) were CD117-positive and DOG-1-positive; 72.4% (21/29) and 51.7% (15/29) were CD34-positive and smooth muscle actin-positive, respectively. In esophageal leiomyomata, 100% (64/64) were smooth muscle actin-positive and desmin-positive; 100% were CD117-negative and DOG-1-negative. No local recurrence was detected in followed up patients (n = 49) after an average of 1.8 years (1.0-3.0 years). IHC analyses are important for distinguishing esophageal stromal tumor from leiomyoma. Early endoscopic resection is an effective treatment option for esophageal stromal tumors >1 cm.

Diagnostic significance of DOG-1 and PKC-θ expression and c-Kit/PDGFRA mutations in gastrointestinal stromal tumours

OBJECTIVE

To investigate discovered on gastrointestinal stromal tumor (GIST)-1 (DOG-1) and protein kinase C-θ (PKC-θ) expression in a series of GISTs and determine the sensitivity, specificity, and diagnostic value of these two antigens.

METHODS

Immnunohistochemistry (IHC) was used to detect CD117, DOG-1, PKC-θ, CD34, Ki-67, α-smooth muscle actin (SMA), S100, and Desmin expression in 147 GISTs and 51 non-GISTs. c-Kit gene (exons 9, 11, 13, and 17) and platelet-derived growth factor receptor-alpha (PDGFRA) gene (exons 12 and 18) mutations were also detected.

RESULTS

About 94.5% GISTs were CD117 positive, 96% were DOG-1 positive, and 90.5% were PKC-θ positive. DOG-1 had a specificity of 100%, while CD117 and PKC-θ had a specificity of 90% and 80%, respectively. There was no significant difference between DOG-1 and PKC-θ expressions when compared to CD117 expression. In 30 out of 42 (71.5%) GISTs, a c-Kit gene mutation was found, and in 3 out of 42 cases (7%), PDGFRA was mutated. Wild-type c-Kit/PDGFRA genes accounted for 21.5% (9/42). Most c-Kit gene mutations were found to be located at exon 11, mainly as in-frame deletions. Mutations in exon 9 were all missense mutations. Most PDGFRA gene mutations were found in exon 18, codon 842. c-Kit gene mutations in exons 13 and 17, and the PDGFRA gene mutation in exon 12 were not detected.

CONCLUSIONS

Compared to CD117, DOG-1 is a biomarker with higher sensitivity and specificity. The combination of CD117 and DOG-1 can be used to improve the diagnosis of GIST. Although PKC-θ has a lower specificity than DOG-1, it can be a useful biomarker, especially in CD117(-) and/or DOG-1(-) cases.

Extended adjuvant therapy with imatinib in patients with gastrointestinal stromal tumors : recommendations for patient selection, risk assessment, and molecular response monitoring

On the basis of the recently published results of a clinical trial comparing 12 and 36 months of imatinib in adjuvant therapy for gastrointestinal stromal tumors (GISTs), which demonstrated clinical benefit of longer imatinib treatment in terms of delaying recurrences and improving overall survival, both the US Food and Drug Administration and the European Medicines Agency have updated their recommendations and approved 36 months of imatinib treatment in patients with v-kit Hardy-Zuckerman 4 feline sarcoma viral oncogene homolog (KIT)-positive GISTs (also known as CD117-positive GISTs) at high risk of recurrence after surgical resection of a primary tumor. This article discusses patient selection criteria for extended adjuvant therapy with imatinib, different classifications of risk of recurrence, and assessment of the response to therapy.

Surgical treatment of gastric gastrointestinal stromal tumor

Gastrointestinal stromal tumor is the most common mesenchymal tumor in the gastrointestinal tract and is most frequently developed in the stomach in the form of submucosal tumor. The incidence of gastric gastrointestinal stromal tumor is estimated to be as high as 25% of the population when all small and asymptomatic tumors are included. Because gastric gastrointestinal stromal tumor is not completely distinguished from other submucosal tumors, a surgical excisional biopsy is recommended for tumors >2 cm. The surgical principles of gastrointestinal stromal tumor are composed of an R0 resection with a normal mucosa margin, no systemic lymph node dissection, and avoidance of perforation, which results in peritoneal seeding even in cases with otherwise low risk profiles. Laparoscopic surgery has been indicated for gastrointestinal stromal tumors <5 cm, and the indication for laparoscopic surgery is expanded to larger tumors if the above mentioned surgical principles can be maintained. A simple exogastric resection and various transgastric resection techniques are used for gastrointestinal stromal tumors in favorable locations (the fundus, body, greater curvature side). For a lesion at the gastroesophageal junction in the posterior wall of the stomach, enucleation techniques have been tried preserve the organ's function. Those methods have a theoretical risk of seeding a ruptured tumor, but this risk has not been evaluated by well-designed clinical trials. While some clinical trials are still on-going, neoadjuvant imatinib is suggested when marginally unresectable or multiorgan resection is anticipated to reduce the extent of surgery and the chance of incomplete resection, rupture or bleeding.

Clinical features and treatment of gastrointestinal stromal tumors: Recent advances

Gastrointestinal stromal tumors (GISTs) are the most common gastrointestinal mesenchymal tumors. The development of molecular biology, pathology and clinical medicine in recent years has deepened our understanding of GISTs. The combination of traditional surgery and molecular targeted drugs is particularly important for the treatment of GISTs. Multi-target and multi-kinase inhibitors such as imatinib and sunitinib have been used for the treatment of unresectable and recurrent GISTs. This paper provides a brief review of gene analysis, pathological characteristics, operational and adjuvant therapy of GISTs.

Pathology of gastrointestinal stromal tumors

Gastrointestinal stromal tumor (GIST) is a well recognized and relatively well understood soft tissue tumor. Early events in GIST development are activating mutations in KIT or PDGFRA, which occur in most GISTs and encode for mutated tyrosine receptor kinases that are therapeutic targets for tyrosine kinase inhibitors, including imatinib and sunitinib. A small minority of GISTs possessing neither KIT nor PDGFRA mutations may have germline mutations in SDH, suggesting a potential role of SDH in the pathogenesis. Immunohistochemical detection of KIT, and more recently DOG1, has proven to be reliable and useful in the diagnosis of GISTs. Because current and future therapies depend on pathologists, it is important that they recognize KIT-negative GISTs, GISTs in specific clinical contexts, GISTs with unusual morphology, and GISTs after treatment. This review focuses on recent developments in the understanding of the biology, immunohistochemical diagnosis, the role of molecular analysis, and risk assessment of GISTs.

Clinical practice guideline for accurate diagnosis and effective treatment of gastrointestinal stromal tumor in Korea

Despite their rarity in incidence and prevalence, gastrointestinal stromal tumors (GISTs) have emerged as a distinct and noteworthy pathogenetic entity. The clinical management of GISTs has rapidly evolved due to the recent elucidation of their oncogenic signal transduction pathway and the introduction of molecular-targeted therapies. Successful management of GISTs requires a multidisciplinary approach firmly based on an accurate histopathologic diagnosis. In 2007, the Korean GIST study group published the first guideline for optimal diagnosis and treatment of GISTs in Korea. The second version of the guideline was published in 2010. Herein, we provide the results of relevant clinical studies for the purpose of further revision to the guideline. We expect this new guideline will enhance the accuracy of diagnosis, as performed by members of the Korean associate of physicians involved in GIST patient care, thus improving the efficacy of treatment.