ISL1 expression is not restricted to pancreatic well-differentiated neuroendocrine neoplasms, but is also commonly found in well and poorly differentiated neuroendocrine neoplasms of extrapancreatic origin

GAD2 Is a Highly Specific Marker for Neuroendocrine Neoplasms of the Pancreas

Glutamate decarboxylase 2 (GAD2) is the most important inhibitory neurotransmitter and plays a role in insulin-producing β cells of pancreatic islets. The limitation of GAD2 expression to a few normal cell types makes GAD2 a potential immunohistochemical diagnostic marker. To evaluate the diagnostic utility of GAD2 immunohistochemistry, a tissue microarray containing 19,202 samples from 152 different tumor entities and 608 samples of 76 different normal tissue types was analyzed. In normal tissues, GAD2 staining was restricted to brain and pancreatic islet cells. GAD2 staining was seen in 20 (13.2%) of 152 tumor categories, including 5 (3.3%) tumor categories containing at least 1 strongly positive case. GAD2 immunostaining was most commonly seen in neuroendocrine carcinomas (58.3%) and neuroendocrine tumors (63.2%) of the pancreas, followed by granular cell tumors (37.0%) and neuroendocrine tumors of the lung (11.1%). GAD2 was only occasionally (<10% of cases) seen in 16 other tumor entities including paraganglioma, medullary thyroid carcinoma, and small cell neuroendocrine carcinoma of the urinary bladder. Data on GAD2 and progesterone receptor (PR) expression (from a previous study) were available for 95 pancreatic and 380 extrapancreatic neuroendocrine neoplasms. For determining a pancreatic origin of a neuroendocrine neoplasm, the sensitivity of GAD2 was 64.2% and specificity 96.3%, while the sensitivity of PR was 56.8% and specificity 92.6%. The combination of PR and GAD2 increased both sensitivity and specificity. GAD2 immunohistochemistry is a highly useful diagnostic tool for the identification of pancreatic origin in case of neuroendocrine neoplasms with unknown site of origin.

Diagnostic Utility of GATA3 and ISL1 in Differentiating Neuroblastoma From Other Pediatric Malignant Small Round Blue Cell Tumors

Accurate diagnosis of neuroblastoma may be challenging, especially with limited or inadequate specimen and at the metastatic sites due to overlapping imaging, histopathologic, and immunohistochemical (immunohistochemistry [IHC]; infidelity among various lineage-associated transcription factors eg FLI1, transducin-like enhancer 1, etc) features. GATA3 and ISL1 have recently been described as markers of neuroblastic differentiation. This study aims at determining the diagnostic utility of GATA3 and ISL1 in differentiating neuroblastoma from other pediatric malignant small round blue cell tumors.

We evaluated GATA3 and ISL1 expression in 74 pediatric small round blue cell tumors that included 23 NMYC-amplified neuroblastomas, 11 EWSR1-rearranged round cell sarcomas, 7 SYT::SSX1-rearranged synovial sarcomas, 5 embryonal rhabdomyosarcomas, 10 Wilms tumors (nephroblastomas), 7 lymphoblastic lymphoma, 7 medulloblastoma, and 4 desmoplastic small round cell tumor.

All 23 neuroblastomas (moderate to strong staining in >50% of the tumor cells), 5 T-lymphoblastic lymphomas (moderate to strong staining in 40%-90% of the tumor cells), and 2 desmoplastic small round cell tumors (weak to moderate staining in 20%-30% of the tumor cells) expressed GATA3, while other tumors were negative. ISL1 immunoreactivity was observed in 22 (96%) neuroblastomas (strong staining in in >50% of the tumor cells, n  =  17; moderate to strong staining in 26%-50% of the tumor cells, n  =  5), 3 embryonal rhabdomyosarcoma (moderate to strong staining in 30%-85% of the tumor cells), 1 synovial sarcoma (weak staining in 20% of the tumor cells), and 7 medulloblastoma (strong staining in 60%-90% of the tumor cells). Other tumors were negative. Overall, GATA3 showed 86% specificity, 100% sensitivity, and 90% accuracy for neuroblastoma, with a positive predictive value (PPV) and negative predictive value (NPV) of 77% and 100%, respectively. ISLI showed 72% specificity, 96% sensitivity, and 81% accuracy for neuroblastoma, with a PPV and NPV of 67% and 97%, respectively. After the exclusion of T-lymphoblastic lymphoma and desmoplastic small round cell tumors, GATA3 had 100% specificity, sensitivity, accuracy, and PPV and NPV for neuroblastoma. Similarly, in pediatric small round blue cell tumors, ISL1 had 100% specificity, sensitivity, accuracy, PPV, and NPV for neuroblastoma, after embryonal rhabdomyosarcoma, synovial sarcoma, and medulloblastoma were excluded.

CONCLUSIONS

GATA3 and ISL1 may be valuable in the diagnostic work-up of neuroblastoma and may reliably be used to support the neuroblastic lineage of pediatric small round blue cell tumors. Furthermore, dual positivity helps in challenging scenarios, when there is equivocal imaging, overlapping IHC features, limited specimen, and the lack of facility for a molecular work up.

Revolutionizing pediatric neuroblastoma treatment: unraveling new molecular targets for precision interventions

Neuroblastoma (NB) is the most frequent solid tumor in pediatric cases, contributing to around 15% of childhood cancer-related deaths. The wide-ranging genetic, morphological, and clinical diversity within NB complicates the success of current treatment methods. Acquiring an in-depth understanding of genetic alterations implicated in the development of NB is essential for creating safer and more efficient therapies for this severe condition. Several molecular signatures are being studied as potential targets for developing new treatments for NB patients. In this article, we have examined the molecular factors and genetic irregularities, including those within insulin gene enhancer binding protein 1 (ISL1), dihydropyrimidinase-like 3 (DPYSL3), receptor tyrosine kinase-like orphan receptor 1 (ROR1) and murine double minute 2-tumor protein 53 (MDM2-P53) that play an essential role in the development of NB. A thorough summary of the molecular targeted treatments currently being studied in pre-clinical and clinical trials has been described. Recent studies of immunotherapeutic agents used in NB are also studied in this article. Moreover, we explore potential future directions to discover new targets and treatments to enhance existing therapies and ultimately improve treatment outcomes and survival rates for NB patients.

European Neuroendocrine Tumour Society (ENETS) 2023 guidance paper for nonfunctioning pancreatic neuroendocrine tumours

This ENETS guidance paper for well-differentiated nonfunctioning pancreatic neuroendocrine tumours (NF-Pan-NET) has been developed by a multidisciplinary working group, and provides up-to-date and practical advice on the management of these tumours. Using the extensive experience of centres treating patients with NF-Pan-NEN, the authors of this guidance paper discuss 10 troublesome questions in everyday clinical practice. Our many years of experience in this field are still being verified in the light of the results of new clinical, which set new ways of proceeding in NEN. The treatment of NF-Pan-NEN still requires a decision of a multidisciplinary team of specialists in the field of neuroendocrine neoplasms.

Renal neuroendocrine tumors: clinical and molecular pathology with an emphasis on frequent association with ectopic Cushing syndrome

Renal neuroendocrine tumors (RenNETs) are rare malignancies with largely unknown biology, hormone expression, and genetic abnormalities. This study aims to improve our understanding of the RenNETs with emphasis of functional, hormonal, and genetic features. Surgically resected RenNETs (N = 13) were retrieved, and immunohistochemistry and next-generation sequencing (NGS) were performed in all cases. In addition, all published RenNETs were systematically reviewed. Our cohort (4 men and 9 women, mean age 42, mean tumor size 7.6 cm) included 2 patients with Cushing syndrome (CS). WHO grade (23% G1, 54% G2, and 23% G3) and tumor progression did not correlate. CS-associated RenNETs (CS-RenNETs) showed a solid and eosinophilic histology and stained for ACTH, while the remaining non-functioning tumors had a trabecular pattern and expressed variably hormones somatostatin (91%), pancreatic polypeptide (63%), glucagon (54%), and serotonin (18%). The transcription factors ISL1 and SATB2 were expressed in all non-functioning, but not in CS-RenNETs. NGS revealed no pathogenic alterations or gene fusions. In the literature review (N = 194), 15 (8%) of the patients had hormonal syndromes, in which CS being the most frequent (7/15). Large tumor size and presence of metastasis were associated with shorter patients' survival (p < 0.01). RenNETs present as large tumors with metastases. CS-RenNETs differ through ACTH production and solid-eosinophilic histology from the non-functioning trabecular RenNETs that produce pancreas-related hormones and express ISL1 and SATB2. MEN1 or DAXX/ARTX abnormalities and fusion genes are not detected in RenNETs, indicating a distinct yet unknown molecular pathogenesis.

Islet-1 Is Differentially Expressed Among Neuroendocrine and Non-Neuroendocrine Tumors and Its Potential Diagnostic Implication

Islet-1 (ISL1) plays key roles in programming the epigenome and facilitating the recruitment of additional regulatory factors. Although it has been used as a marker for pancreatic neuroendocrine tumors (PanNETs), ISL1 reactivity in other tumor types are critically missing. ISL1 immunohistochemistry was performed on 147 neuroendocrine tumors (NET) originated in pancreas, gastrointestinal tract, lung, thyroid, parathyroid, pituitary, adrenal medulla, head/neck, genitourinary tract, and skin; and 110 non-neuroendocrine tumors originated in the pancreas, thymus, lung, thyroid, mesothelium, adrenal cortex, stomach, breast, head/neck, skin, and kidney. ISL1 nuclear staining was observed in normal thymic epithelium, pancreatic islets, adrenal medulla, and pituitary gland cells as well as frequently in tumors of these origins: pancreatic NET (78%), paraganglioma/pheochromocytoma (100%), thymoma (82%), and pituitary NET (50%). ISL1 was also variably expressed in certain non-pancreatic NET such as Merkel cell carcinoma (100%), medullary carcinoma of the thyroid (100%), head/neck NEC (80%), genitourinary NEC (71%), lung small cell carcinoma (46%), lung carcinoids (17%), lower intestinal tract NET (93%) but not in upper gastrointestinal tract NET nor parathyroid adenoma. For other non-NETs, focal ISL1 expression was less frequently detected in gastric adenocarcinoma (40%), mesothelioma (29%), adrenal cortical carcinoma (17%), and squamous carcinoma (24%), but not in others tested. ISL1 is not a pan-NE marker as it is consistently lacking in upper gastrointestinal NET and parathyroid adenoma. It is also differentially expressed in thymoma. ISL1 immunohistochemnistry could help to differentiate PanNET and lower intestinal NET from upper gastrointestinal NET and be used as a marker for thymoma.

Diagnostic Approaches for Neuroendocrine Neoplasms of Unknown Primary (NEN-UPs) and Their Prognostic Relevance-A Retrospective, Long-Term Single-Center Experience

Neuroendocrine neoplasms (NENs) represent a rare and heterogenous group of tumors with predominantly gastroenteropancreatic or pulmonary origin. Despite numerous diagnostic efforts, the primary tumor site remains unknown in up to 20% of the patients diagnosed with NEN. In this subgroup of NEN patients, a standard diagnostic algorithm has not yet been integrated into clinical routine. Of note, an undetermined primary tumor site in NENs is associated with an impaired clinical outcome by at least "formally" limiting treatment options exclusively approved for NENs of a certain histological origin. In this retrospective study, a patient cohort of 113 patients initially diagnosed with NEN of unknown primary (NEN-UP) was analyzed. In 13 patients (11.5%) a primary tumor site could be identified subsequently, amongst others, by performing somatostatin receptor (SSTR)-PET-based imaging, which was irrespective of the initial clinical or demographic features. Diagnostic work-up and therapeutic regimens did not differ significantly between patients with an identified or unidentified primary tumor site; only a detailed immunohistochemical assessment providing additional information on the tumor origin proved to be significantly associated with the detection of a primary tumor site. Our study revealed that a profound diagnostic work-up, particularly including SSTR-PET-based imaging, leads to additional treatment options, finally resulting in significantly improved clinical outcomes for patients with NEN-UPs.

YAP1 and WWTR1 expression inversely correlates with neuroendocrine markers in Merkel cell carcinoma

BackgroundMerkel cell carcinoma (MCC) is an aggressive neuroendocrine (NE) skin cancer caused by severe UV-induced mutations or expression of Merkel cell polyomavirus (MCPyV) large and small T antigens (LT and ST). Despite deep genetic differences between MCPyV-positive and -negative subtypes, current clinical diagnostic markers are indistinguishable, and the expression profile of MCC tumors is, to our knowledge, unexplored.MethodsHere, we leveraged bulk and single-cell RNA-Seq of patient-derived tumor biopsies and cell lines to explore the underlying transcriptional environment of MCC.ResultsStrikingly, MCC samples could be separated into transcriptional subtypes that were independent of MCPyV status. Instead, we observed an inverse correlation between a NE gene signature and the Hippo pathway transcription factors Yes1-associated transcriptional regulator (YAP1) and WW domain-containing transcriptional regulator 1 (WWTR1). This inverse correlation was broadly present at the transcript and protein levels in the tumor biopsies as well as in established and patient-derived cell lines. Mechanistically, expression of YAP1 or WWTR1 in a MCPyV-positive MCC cell line induced cell-cycle arrest at least in part through TEA domain-dependent (TEAD-dependent) transcriptional repression of MCPyV LT.ConclusionThese findings identify what we believe to be a previously unrecognized heterogeneity in NE gene expression within MCC and support a model of YAP1/WWTR1 silencing as essential for the development of MCPyV-positive MCC.FundingUS Public Health Service grants R35CA232128, P01CA203655, and P30CA06516.

All Together Now: Standardization of Nomenclature for Neuroendocrine Neoplasms across Multiple Organs

Neuroendocrine neoplasms (NENs) span virtually all organ systems and exhibit a broad spectrum of behavior, from indolent to highly aggressive. Historically, nomenclature and grading practices have varied widely across, and even within, organ systems. However, certain core features are recapitulated across anatomic sites, including characteristic morphology and the crucial role of proliferative activity in prognostication. A recent emphasis on unifying themes has driven an increasingly standardized approach to NEN classification, as delineated in the World Health Organization's Classification of Tumours series. Here, we review recent developments in NEN classification, with a focus on NENs of the pancreas and lungs.

Long-term organoid culture of a small intestinal neuroendocrine tumor

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare and highly heterogeneous neoplasms whose incidence has markedly increased over the last decades. A grading system based on the tumor cells' proliferation index predicts high-risk for G3 NETs. However, low-to-intermediate grade (G1/G2) NETs have an unpredictable clinical course that varies from indolent to highly malignant. Cultures of human cancer cells enable to perform functional perturbation analyses that are instrumental to enhance our understanding of cancer biology. To date, no tractable and reliable long-term culture of G1/G2 NET has been reported to permit disease modeling and pharmacological screens. Here, we report of the first long-term culture of a G2 metastatic small intestinal NET that preserves the main genetic drivers of the tumor and retains expression patterns of the endocrine cell lineage. Replicating the tissue, this long-term culture showed a low proliferation index, and yet it could be propagated continuously without dramatic changes in the karyotype. The model was readily available for pharmacological screens using targeted agents and as expected, showed low tumorigenic capacity in vivo. Overall, this is the first long-term culture of NETs to faithfully recapitulate many aspects of the original neuroendocrine tumor.

Archetype tasks link intratumoral heterogeneity to plasticity and cancer hallmarks in small cell lung cancer

Small cell lung cancer (SCLC) tumors comprise heterogeneous mixtures of cell states, categorized into neuroendocrine (NE) and non-neuroendocrine (non-NE) transcriptional subtypes. NE to non-NE state transitions, fueled by plasticity, likely underlie adaptability to treatment and dismal survival rates. Here, we apply an archetypal analysis to model plasticity by recasting SCLC phenotypic heterogeneity through multi-task evolutionary theory. Cell line and tumor transcriptomics data fit well in a five-dimensional convex polytope whose vertices optimize tasks reminiscent of pulmonary NE cells, the SCLC normal counterparts. These tasks, supported by knowledge and experimental data, include proliferation, slithering, metabolism, secretion, and injury repair, reflecting cancer hallmarks. SCLC subtypes, either at the population or single-cell level, can be positioned in archetypal space by bulk or single-cell transcriptomics, respectively, and characterized as task specialists or multi-task generalists by the distance from archetype vertex signatures. In the archetype space, modeling single-cell plasticity as a Markovian process along an underlying state manifold indicates that task trade-offs, in response to microenvironmental perturbations or treatment, may drive cell plasticity. Stifling phenotypic transitions and plasticity may provide new targets for much-needed translational advances in SCLC. A record of this paper's Transparent Peer Review process is included in the supplemental information.

Aberrant transcription factors in the cancers of the pancreas

Transcription factors (TFs) are essential for proper activation of gene set during the process of organogenesis, differentiation, lineage specificity. Reactivation or dysregulation of TFs regulatory networks could lead to deformation of organs, diseases including various malignancies. Currently, understanding the mechanism of oncogenesis became necessity for the development of targeted therapeutic strategy for different cancer types. It is evident that many TFs go awry in cancers of the pancreas such as pancreatic ductal adenocarcinoma (PDAC) and pancreatic neuroendocrine neoplasms (PanNENs). These mutated or dysregulated TFs abnormally controls various signaling pathways in PDAC and PanNENs including RTK, PI3K-PTEN-AKT-mTOR, JNK, TGF-β/SMAD, WNT/β-catenin, SHH, NOTCH and VEGF which in turn regulate different hallmarks of cancer. Aberrant regulation of such pathways have been linked to the initiation, progression, metastasis, and resistance in pancreatic cancer. As of today, a number of TFs has been identified as crucial regulators of pancreatic cancer and a handful of them shown to have potential as therapeutic targets in pre-clinical and clinical settings. In this review, we have summarized the current knowledge on the role and therapeutic usefulness of TFs in PDAC and PanNENs.

Investigation of the RB1-SOX2 axis constitutes a tool for viral status determination and diagnosis in Merkel cell carcinoma

MCC (Merkel cell carcinoma) is an aggressive neuroendocrine cutaneous neoplasm. Integration of the Merkel cell polyomavirus (MCPyV) is observed in about 80% of the cases, while the remaining 20% are related to UV exposure. Both MCPyV-positive and -negative MCCs-albeit by different mechanisms-are associated with RB1 inactivation leading to overexpression of SOX2, a major contributor to MCC biology. Moreover, although controversial, loss of RB1 expression seems to be restricted to MCPyV-negative cases.The aim of the present study was to assess the performances of RB1 loss and SOX2 expression detected by immunohistochemistry to determine MCPyV status and to diagnose MCC, respectively.Overall, 196 MCC tumors, 233 non-neuroendocrine skin neoplasms and 70 extra-cutaneous neuroendocrine carcinomas (NEC) were included. SOX2 and RB1 expressions were assessed by immunohistochemistry in a tissue micro-array. Diagnostic performances were determined using the likelihood ratio (LHR).RB1 expression loss was evidenced in 27% of the MCC cases, 12% of non-neuroendocrine skin tumors and 63% of extra-cutaneous NEC. Importantly, among MCC cases, RB1 loss was detected in all MCPyV(-) MCCs, while MCPyV( +) cases were consistently RB1-positive (p < 0.001). SOX2 diffuse expression was observed in 92% of the MCC cases and almost never observed in non-neuroendocrine skin epithelial neoplasms (2%, p < 0.0001, LHR +  = 59). Furthermore, SOX2 diffuse staining was more frequently observed in MCCs than in extra-cutaneous NECs (30%, p < 0.001, LHR +  = 3.1).These results confirm RB1 as a robust predictor of MCC viral status and further suggest SOX2 to be a relevant diagnostic marker of MCC.

Pheochromocytomas and Abdominal Paragangliomas: A Practical Guidance

Simple Summary

Pheochromocytomas and abdominal paragangliomas (PPGLs) are rare. They can be discovered incidentally by imaging with computed tomography or magnetic resonance imaging and during hormonal surveillance in patients with known genetic variants that are associated with PPGLs. As most PPGLs are functioning, a hormonal work-up evaluating for catecholamine excess is recommended. Classical symptoms, such as tachycardia, hypertension and headache, can be present, but when the PPGL is discovered as an incidentaloma, symptoms may be lacking or be more discrete. PPGLs carry malignant potential, and patients should undergo close surveillance, as recurrence of disease or metastasis may develop. Genetic susceptibility for multifocal disease has gained more attention, and germline variants are commonly detected, thus facilitating detection of hereditary cases and afflicted family members. Any patient with a PPGL should be managed by an expert multidisciplinary team consisting of endocrinologists, radiologists, surgeons, pathologists and clinical geneticists.

Abstract

Pheochromocytomas and abdominal paragangliomas (PPGLs) are rare tumors arising from the adrenal medulla or the sympathetic nervous system. This review presents a practical guidance for clinicians dealing with PPGLs. The incidence of PPGLs has risen. Most cases are detected via imaging and less present with symptoms of catecholamine excess. Most PPGLs secrete catecholamines, with diffuse symptoms. Diagnosis is made by imaging and tests of catecholamines. Localized disease can be cured by surgery. PPGLs are the most heritable of all human tumors, and germline variants are found in approximately 30–50% of cases. Such variants can give information regarding the risk of developing recurrence or metastases as well as the risk of developing other tumors and may identify relatives at risk for disease. All PPGLs harbor malignant potential, and current histological and immunohistochemical algorithms can aid in the identification of indolent vs. aggressive tumors. While most patients with metastatic PPGL have slowly progressive disease, a proportion of patients present with an aggressive course, highlighting the need for more effective therapies in these cases. We conclude that PPGLs are rare but increasing in incidence and management should be guided by a multidisciplinary team.

Emerging Biomarkers in Thyroid Practice and Research

Simple Summary

Tumor biomarkers are molecules at genetic or protein level, or certain evaluable characteristics. These help in perfecting patient management. Over the past decade, advanced and more sensitive techniques have led to the identification of many new biomarkers in the field of oncology. A knowledge of the recent developments is essential for their application to clinical practice, and furthering research. This review provides a comprehensive account of such various markers identified in thyroid carcinoma, the most common endocrine malignancy. While some of these have been brought into use in routine patient management, others are novel and need more research before clinical application.

Abstract

Thyroid cancer is the most common endocrine malignancy. Recent developments in molecular biological techniques have led to a better understanding of the pathogenesis and clinical behavior of thyroid neoplasms. This has culminated in the updating of thyroid tumor classification, including the re-categorization of existing and introduction of new entities. In this review, we discuss various molecular biomarkers possessing diagnostic, prognostic, predictive and therapeutic roles in thyroid cancer. A comprehensive account of epigenetic dysregulation, including DNA methylation, the function of various microRNAs and long non-coding RNAs, germline mutations determining familial occurrence of medullary and non-medullary thyroid carcinoma, and single nucleotide polymorphisms predisposed to thyroid tumorigenesis has been provided. In addition to novel immunohistochemical markers, including those for neuroendocrine differentiation, and next-generation immunohistochemistry (BRAF V600E, RAS, TRK, and ALK), the relevance of well-established markers, such as Ki-67, in current clinical practice has also been discussed. A tumor microenvironment (PD-L1, CD markers) and its influence in predicting responses to immunotherapy in thyroid cancer and the expanding arena of techniques, including liquid biopsy based on circulating nucleic acids and plasma-derived exosomes as a non-invasive technique for patient management, are also summarized.

Neuroendocrine neoplasms of the pancreas: diagnosis and pitfalls

Common to neuroendocrine neoplasms of the pancreas is their expression of synaptophysin, chromogranin A, and/or INSM1. They differ, however, in their histological differentiation and molecular profile. Three groups can be distinguished: well-differentiated neuroendocrine neoplasms (neuroendocrine tumors), poorly differentiated neuroendocrine neoplasms (neuroendocrine carcinomas), and mixed neuroendocrine-non-neuroendocrine neoplasms. However, the expression of synaptophysin and, to a lesser extent, also chromogranin A is not restricted to the neuroendocrine neoplasms, but may also be in a subset of non-neuroendocrine epithelial and non-epithelial neoplasms. This review provides the essential criteria for the diagnosis of pancreatic neuroendocrine neoplasms including diagnostic clues for the distinction of high-grade neuroendocrine tumors from neuroendocrine carcinomas and an algorithm avoiding diagnostic pitfalls in the delineation of non-neuroendocrine neoplasms with neuroendocrine features from pancreatic neuroendocrine neoplasms.

An analysis of 130 neuroendocrine tumors G3 regarding prevalence, origin, metastasis, and diagnostic features

Limited data exist on high-grade neuroendocrine tumors (NETs G3) which represent a new category among neuroendocrine neoplasms (NEN). We analyzed NETs G3 in a consultation series regarding prevalence, origin, metastasis, and diagnostic problems. Based on the WHO classification of digestive system tumors, 130 NETs G3 (9%) were identified in 1513 NENs. NET G3 samples were more often obtained from metastatic sites (69%) than NET G1/G2 samples (24%). NET G3 metastases presented most frequently in the liver (74%) and originated from the pancreas (38/90, 42%), followed by the lung (9%), ileum (7%), stomach (3%), rectum (1%), and rare sites (2%) such as the prostate and breast. The primaries remained unknown in 15%. NETs G3 had a median Ki67 of 30% that distinguished them from NECs (60%), though with great overlap. The expression of site-specific markers, p53, Rb1, and SST2 was similar in NETs G3 and NETs G1/G2, except for p53 and Rb1 which were abnormally expressed in 8% and 7% of liver metastases from NET G3 but not from NET G1/G2. NETs G3 were frequently referred as NECs (39%) but could be well distinguished from NECs by normal p53 (92% versus 21%) and Rb1 expression (93% versus 41%) expression. In conclusion, NETs G3 are frequently discovered as liver metastases from pancreatic or pulmonary primaries and are often misinterpreted as NEC. p53 and Rb1 are powerful markers in the distinction of NET G3 from NEC. Rarely, carcinomas from non-digestive, non-pulmonary organs with neuroendocrine features may present as NET G3.

Second-Generation Neuroendocrine Immunohistochemical Markers: Reflections from Clinical Implementation

Simple Summary

Neuroendocrine tumors are a collection of neoplastic lesions arising in cells with traits similar to hormone-producing and nerve cells with the ability to secrete peptide hormones using an intricate vesicle transportation system. From a clinical standpoint, neuroendocrine tumors are unique in terms of therapeutic modalities, and a correct diagnosis is therefore imperative in order for the patient to obtain the most efficient treatment. In this process, the pathologist can analyze if the tumor cells express Chromogranin A and Synaptophysin, two proteins associated with the regulation of secretory vesicles. Unfortunately, these markers are not always present in neuroendocrine tumors, and non-neuroendocrine tumors may also occasionally express Chromogranin A or Synaptophysin—making the diagnosis difficult to make for certain cases. Recently, three proteins termed ISL1, INSM1 and Secretagogin were found to be selectively expressed in neuroendocrine cells, and subsequent studies have identified their potential as markers of neuroendocrine differentiation in the clinical setting. In this commentary, the benefits of these novel “second-generation” markers are briefly discussed from a clinical context.

Abstract

When analyzing tumors by histopathology, endocrine pathologists have traditionally been restricted to a few key immunohistochemical markers related to secretory vesicles in order to pinpoint neuroendocrine differentiation—most notably Chromogranin A (CGA) and Synaptophysin (SYP). Although proven of great clinical utility, these markers sometimes exhibit tissue-specific patterns depending on tumor origin, and non-neuroendocrine tumors might sometimes display focal expression. Moreover, CGA and SYP might be partially or totally absent in highly proliferative neuroendocrine carcinomas, making the diagnosis particularly challenging on small biopsies of metastatic lesions with unknown location of the primary tumor. The advent of second-generation neuroendocrine markers ISL LIM Homeobox 1 (ISL1), INSM Transcriptional Repressor 1 (INSM1) and Secretagogin (SECG) have expanded the pathology toolbox considerably, constituting markers that often retain expression even in poorly differentiated neuroendocrine carcinomas. As non-neuroendocrine tumors seldom express these antigens, the specificity of ISL1, INSM1 and SECG make them welcome additions to clinical practice. In this commentary, recent advances of this field as well as initial clinical experiences from a tertiary neuroendocrine center are discussed.

ISL1 promoted tumorigenesis and EMT via Aurora kinase A-induced activation of PI3K/AKT signaling pathway in neuroblastoma

Neuroblastoma (NB) is the most common extracranial solid malignancy in children and its mortality rate is relatively high. However, driver genes of NB are not clearly identified. Using bioinformatics analysis, we determined the top 8 differentially expressed genes (DEGs) in NB, including GFAP, PAX6, FOXG1, GAD1, PTPRC, ISL1, GRM5, and GATA3. Insulin gene enhancer binding protein 1 (ISL1) is a LIM homeodomain transcription factor which has been found to be highly expressed in a variety of malignant tumors, but the function of ISL1 in NB has not been fully elucidated. We identified ISL1 as an oncogene in NB. ISL1 is preferentially upregulated in NB tissues compared with normal tissues. High ISL1 expression is significantly associated with poor outcome of NB patients. Knockdown of ISL1 markedly represses proliferation and induces cell apoptosis in vitro, and suppresses tumorigenicity in vivo, while overexpression of ISL1 has the opposite effects. Mechanistically, we demonstrate that ISL1 promotes cell proliferation and EMT transformation through PI3K/AKT signaling pathway by upregulating Aurora kinase A (AURKA), a serine-threonine kinase that is essential for the survival of NB cells. The blockade of AURKA attenuates the function of ISL1 overexpression in the regulation of cell proliferation and migration, Conclusively, this study showed that ISL1 targeted AURKA to facilitate the development of NB, which provided new insights into the tumorigenesis of NB. Thus, ISL1 may be a promising therapeutic target in the future.

Recent Advances in Digestive Tract Tumors: Updates From the 5th Edition of the World Health Organization "Blue Book"

CONTEXT.—

The World Health Organization Classification of Tumours: Digestive System Tumors, 5th edition, was published in 2019 and shows several impactful changes as compared with the 4th edition published in 2010. Changes include a revised nomenclature of serrated lesions and revamping the classification of neuroendocrine neoplasms. Appendiceal goblet cell adenocarcinoma is heavily revised, and intrahepatic cholangiocarcinoma is split into 2 subtypes. New subtypes of colorectal carcinoma and hepatocellular carcinoma are described. Precursor lesions are emphasized with their own entries, and both dysplastic and invasive lesions are generally recommended to be graded using a 2-tier system. Hematolymphoid tumors, mesenchymal tumors, and genetic tumor syndromes each have their own sections in the 5th edition. New hematolymphoid lesions include monomorphic epitheliotropic intestinal T-cell lymphoma; duodenal-type follicular lymphoma; intestinal T-cell lymphoma, not otherwise specified; and indolent T-cell lymphoproliferative disorder of the gastrointestinal tract. This paper will provide an in-depth look at the changes in the 5th edition as compared with the 4th edition.

OBJECTIVE.—

To provide a comprehensive, in-depth update on the World Health Organization classification of digestive tumors, including changes to nomenclature, updated diagnostic criteria, and newly described entities.

DATA SOURCES.—

The 5th edition of the World Health Organization Classification of Tumours: Digestive System Tumours, as well as the 4th edition.

CONCLUSIONS.—

The World Health Organization has made many key changes in its newest update on tumors of the digestive system. Pathologists should be aware of these changes and incorporate them into their practice as able or necessary.

Expression of ISL1 and its partners in prostate cancer progression and neuroendocrine differentiation

INTRODUCTION AND OBJECTIVES

ISL1 serves as a biomarker of metastasis and neuroendocrine neoplasia in multiple tumors. However, the expression and relation of ISL1 to other biomarkers in prostate cancer have not been fully elucidated. Here, we characterize the expression of ISL1 and its partners in PCa and document its association to disease progression and post castration resistance neuroendocrine differentiation.

METHODS

The expression of ISL1 was interrogated in > 6000 primary samples from the Decipher GRID registry and 250 mCRPC samples to assess its prognostic value and relation to neuroendocrine differentiation.

RESULTS

ISL1 was highly correlated to MEIS genes and other genes related to cell motility. ISL1 down-regulation in PCa was associated with cancer progression, aggressive primary tumors, and metastatic outcome. We found that ISL1 is highly correlated to MEIS genes across multiple primary PCa and mCRPC cohorts. The expression of ISL1 and MEIS genes were significantly and inversely related to metastasis-free survival and lethal disease, and were downregulated in CRPC and hormone naïve metastatic tumors but showed upregulation in neuroendocrine tumors. Co-immunoprecipitation showed MEIS2 and ISL1 interacting with each supporting their role in modulating transcriptional regulation and nominating this complex for potential targeted therapy.

CONCLUSIONS

ISL1 complex with MEIS2 serves a critical role in prostate tumor progression and its upregulation in mCRPC/NE provides a rationale for assessing the role of ISL1 and its associated protein in treatment resistance.

An algorithmic approach utilizing CK7, TTF1, beta-catenin, CDX2, and SSTR2A can help differentiate between gastrointestinal and pulmonary neuroendocrine carcinomas

Primary gastrointestinal neuroendocrine carcinoma (GI-NEC) cannot be distinguished morphologically from pulmonary neuroendocrine carcinoma (P-NEC). This can present a significant diagnostic challenge in cases where site of origin cannot be readily determined. To identify immunohistochemical (IHC) markers that can be used to reliably distinguish between GI-NECs and P-NECs, we constructed 3-mm tissue microarrays, one containing 13 GI-NECs and one containing 20 P-NECs. IHC was performed on both microarrays using 21 stains: AE1/AE3, CK7, CK20, synaptophysin, chromogranin, CD56, INSM1, SSTR2A, CDX2, SATB2, TTF1, Napsin A, PR, GATA3, PAX8, ISL1, beta-catenin, AFP, SMAD4, Rb, and p53. For GI-NEC, the most strongly expressed marker was synaptophysin (mean H-score 248), while AE1/AE3 was the most strongly expressed in P-NEC (mean H-score 230), which was stronger than in GI-NEC (p = 0.011). Other markers that were stronger overall in P-NEC than in GI-NEC included CK7 (p < 0.0001) and TTF1 (p < 0.0001). Markers that were stronger overall in GI-NEC than in P-NEC included SSTR2A (p = 0.0021), SATB2 (p = 0.018), CDX2 (p = 0.019), and beta-catenin (nuclear; p = 0.029). SMAD4, Rb, and p53 showed similar rates of abnormal protein expression. Based on these results, a stepwise algorithmic approach utilizing CK7, TTF1, beta-catenin, CDX2, and SSTR2A had a 91% overall accuracy in distinguishing these GI-NEC from P-NEC. This was tested on a second cohort of 10 metastatic GI-NEC and 10 metastatic P-NEC, with an accuracy in this cohort of 85% and an overall accuracy of 89% for the 53 cases tested. Our algorithm reasonably discriminates GI-NEC from P-NEC using currently available IHC stains.

Insulin gene enhancer protein 1 mediates glycolysis and tumorigenesis of gastric cancer through regulating glucose transporter 4

Background

Insulin gene enhancer protein 1, (ISL1), a LIM‐homeodomain transcription factor, is involved in multiple tumors and is associated with insulin secretion and metabolic phenotypes. However, the role of ISL1 in stimulating glycolysis to promote tumorigenesis in gastric cancer (GC) is unclear. In this study, we aimed to characterize the expression pattern of ISL1 in GC patients and explore its molecular biological mechanism in glycolysis and tumorigenesis.

Methods

We analyzed the expression and clinical significance of ISL1 in GC using immunohistochemistry and real‐time polymerase chain reaction (PCR). Flow cytometry and IncuCyte assays were used to measure cell proliferation after ISL1 knockdown. RNA‐sequencing was performed to identify differentially expressed genes, followed by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and Gene Set Enrichment Analysis (GSEA) to reveal key signaling pathways likely regulated by ISL1 in GC. Alteration of the glycolytic ability of GC cells with ISL1 knockdown was validated by measuring the extracellular acidification rate (ECAR) and oxygen consumption rate (OCR) and by detecting glucose consumption and lactate production. The expression of glucose transporter 4 (GLUT4) and ISL1 was assessed by Western blotting, immunohistochemistry, and immunofluorescent microscopy. The luciferase reporter activity and chromatin immunoprecipitation assays were performed to determine the transcriptional regulation of ISL1 on GLUT4.

Results

High levels of ISL1 and GLUT4 expression was associated with short survival of GC patients. ISL1 knockdown inhibited cell proliferation both in vitro and in vivo. KEGG analysis and GSEA for RNA‐sequencing data indicated impairment of the glycolysis pathway in GC cells with ISL1 knockdown, which was validated by reduced glucose uptake and lactate production, decreased ECAR, and increased OCR. Mechanistic investigation indicated that ISL1 transcriptionally regulated GLUT4 through binding to its promoter.

Conclusion

ISL1 facilitates glycolysis and tumorigenesis in GC via the transcriptional regulation of GLUT4.

Neuroendocrine neoplasms of the biliary tree, liver and pancreas: a pathological approach

Neuroendocrine neoplasms of the pancreatobiliary tract and liver are a heterogeneous group that encompass a spectrum of entities with distinct morphological, biological and clinical features. Although in the various anatomical sub-sites of this region they show specific characteristics, these tumors, as a whole, share several etiological and clinical aspects. This review systematically addresses NENs arising in the extrahepatic bile ducts, gallbladder, liver and pancreas, with the principal aim of pinpointing essential diagnostic and classification issues. In addition, the section on hepatic NENs has been expanded to include metastatic disease of unknown primary site.

Clinical Routine Application of the Second-generation Neuroendocrine Markers ISL1, INSM1, and Secretagogin in Neuroendocrine Neoplasia: Staining Outcomes and Potential Clues for Determining Tumor Origin

Neuroendocrine neoplasms (NENs) have traditionally been identified via expression of proteins associated to the regulation of secretory vesicles and granules. We report the clinical usage of the "second-generation" proteins ISL LIM homeobox 1 (ISL1), INSM transcriptional repressor 1 (INSM1), and secretagogin (SECG) as immunohistochemical markers of neuroendocrine differentiation since their introduction in clinical routine and compare the results with the established proteins chromogranin A (CGA) and synaptophysin (SYP). In total, 161 tumors, including 139 NENs and 22 "non-NENs" (unrelated tumors with an initial suspicion of NEN), were informatively stained for ISL1, and subsets were also interrogated for INSM1 and/or SECG. Diffuse or focal positive immunoreactivity was noted for ISL1 in 91/139 NENs (65%) and in 6/22 (27%) non-NENs, for INSM1 in 76/85 NENs (89%) and in 2/5 (40%) non-NENs, and for SECG in 49 out of 64 NENs (77%) and in 0/5 non-NENs (0%). Generally, ISL1, INSM1, and SECG exhibited sensitivities in line with or slightly below that of CGA and SYP-largely attributable to tissue-specific patterns regarding tumoral origin. Moreover, for pancreatic and small intestinal NENs, the two largest subgroups, ISL1 staining results were consistent irrespectively of tumor source and WHO grade. We verify previously suggested immunohistochemical schemes of neuroendocrine markers of first- and second-generations to facilitate the diagnostic process for NENs and confirm that the second-generation neuroendocrine markers display tissue-specific patterns. We therefore recommend their implementation in tertiary endocrine pathology centers, not least to aid in the identification of primary tumors when analyzing metastases.

The U2AF2 /circRNA ARF1/miR-342-3p/ISL2 feedback loop regulates angiogenesis in glioma stem cells

BACKGROUND

Glioma is the most common and lethal primary brain tumor in adults, and angiogenesis is one of the key factors contributing to its proliferation, aggressiveness, and malignant transformation. However, the discovery of novel oncogenes and the study of its molecular regulating mechanism based on circular RNAs (circRNAs) may provide a promising treatment target in glioma.

METHODS

Bioinformatics analysis, qPCR, western blotting, and immunohistochemistry were used to detect the expression levels of ISL2, miR-342-3p, circRNA ARF1 (cARF1), U2AF2, and VEGFA. Patient-derived glioma stem cells (GSCs) were established for the molecular experiments. Lentiviral-based infection was used to regulate the expression of these molecules in GSCs. The MTS, EDU, Transwell, and tube formation assays were used to detect the proliferation, invasion, and angiogenesis of human brain microvessel endothelial cells (hBMECs). RNA-binding protein immunoprecipitation, RNA pull-down, dual-luciferase reporter, and chromatin immunoprecipitation assays were used to detect the direct regulation mechanisms among these molecules.

RESULTS

We first identified a novel transcription factor related to neural development. ISL2 was overexpressed in glioma and correlated with poor patient survival. ISL2 transcriptionally regulated VEGFA expression in GSCs and promoted the proliferation, invasion, and angiogenesis of hBMECs via VEGFA-mediated ERK signaling. Regarding its mechanism of action, cARF1 upregulated ISL2 expression in GSCs via miR-342-3p sponging. Furthermore, U2AF2 bound to and promoted the stability and expression of cARF1, while ISL2 induced the expression of U2AF2, which formed a feedback loop in GSCs. We also showed that both U2AF2 and cARF1 had an oncogenic effect, were overexpressed in glioma, and correlated with poor patient survival.

CONCLUSIONS

Our study identified a novel feedback loop among U2AF2, cARF1, miR-342-3p, and ISL2 in GSCs. This feedback loop promoted glioma angiogenesis, and could provide an effective biomarker for glioma diagnosis and prognostic evaluation, as well as possibly being used for targeted therapy.

Pancreatic neuroendocrine tumors with somatostatin expression and paraganglioma-like features

A small fraction of pancreatic neuroendocrine tumors (PanNETs) shows a solid, paraganglioma-like (PG-like) histology. We wanted to know whether these PanNETs have a special hormone expression and are related to paragangliomas (PGs)/pheochromocytomas (PCs). We screened a series of 48 surgically resected PanNETs for their histological growth patterns and their association with expression of islet hormones. The PanNETs were divided into PG-like and non-PG-like tumors and immunohistochemically monitored for the expression of islet hormones, cytokeratins, and S100. The results were correlated to histological pattern, lymph node status, and data in 28 PGs/PCs, including 2 PGs attached to the pancreas. All PanNETs, in contrast to PGs/PCs, were cytokeratin positive. A PG-like growth pattern was identified in 9 of 48 PanNETs and correlated with somatostatin expression. Only half of the non-PG-like PanNETs also contained somatostatin-positive cells. Eight of 28 PGs/PCs expressed somatostatin, mostly in individual cells. PG-like PanNETs and non-PG-like PanNETs infiltrated the adjacent pancreatic tissue, whereas 2 to the pancreas-associated PGs were well demarcated. Lymph node metastases were detected in 58%, 39%, 57%, and 53% of the somatostatin-producing, somatostatin-negative, PG-like, and non-PG-like PanNETs, respectively. PG-like PanNETs, in contrast to PG/PCs, are characterized by the expression of cytokeratin and somatostatin, the development of lymph node metastasis, and the infiltration into pancreatic parenchyma. Non-PG-like PanNETs may also express somatostatin and show lymph node metastases to the same extent. A literature review of cases reported as PG of the pancreas reveals that only a small fraction of these tumors probably represents true pancreatic PGs.

Downregulated Pancreatic Beta Cell Genes Indicate Poor Prognosis in Patients With Pancreatic Neuroendocrine Neoplasms

OBJECTIVE

To predict metachronous liver metastasis after pancreatectomy for pancreatic neuroendocrine neoplasms (Pan-NENs).

SUMMARY OF BACKGROUND DATA

Liver metastasis determines the prognosis of patients with Pan-NENs, but no index exists in the WHO 2017 classification for this prediction.

METHODS

Between April 2014 and March 2018, resected primary tumors from 20 patients with or without simultaneous liver metastasis were examined using genome-wide gene expression analysis. For validation analysis, resected primary tumors from 62 patients without simultaneous liver metastasis were examined for PAX6 expression.

RESULTS

Gene expression profiling revealed pancreatic beta cell genes (NES, -2.0; P < 0.001) as the most downregulated set in patients with simultaneous liver metastasis. In the test study, PAX6 was the most valuable index for liver metastasis (log FC, -3.683; P = 0.0096). Multivariate analysis identified PAX6 expression (hazard ratio, 0.2; P = 0.03) as an independent risk factor for metachronous liver metastasis-free survival (mLM-FS). The 5-year mLM-FS of patients with high versus low PAX6 expression was significantly better (95% vs 66%, respectively; P < 0.0001). The 5-year overall survival rate of was also better than in those with high versus low PAX6 expression (100% vs 87%, respectively). Patients with low PAX 6 expression were significantly younger and leaner, had a higher Ki-67 index (P = 0.01, 0.007, 0.008, respectively), and showed a higher mitotic rate than patients with high PAX6 expression.

CONCLUSIONS

Downregulated pancreatic beta cell genes involving PAX6 in primary tumors may predict mLM and poor overall survival after primary tumor resection in Pan-NEN patients.

An Algorithmic Immunohistochemical Approach to Define Tumor Type and Assign Site of Origin

Immunohistochemistry represents an indispensable complement to an epidemiology and morphology-driven approach to tumor diagnosis and site of origin assignment. This review reflects the state of my current practice, based on 15-years' experience in Pathology and a deep-dive into the literature, always striving to be better equipped to answer the age old questions, "What is it, and where is it from?" The tables and figures in this manuscript are the ones I "pull up on the computer" when I am teaching at the microscope and turn to myself when I am (frequently) stuck. This field is so exciting because I firmly believe that, through the application of next-generation immunohistochemistry, we can provide better answers than ever before. Specific topics covered in this review include (1) broad tumor classification and associated screening markers; (2) the role of cancer epidemiology in determining pretest probability; (3) broad-spectrum epithelial markers; (4) noncanonical expression of broad tumor class screening markers; (5) a morphologic pattern-based approach to poorly to undifferentiated malignant neoplasms; (6) a morphologic and immunohistochemical approach to define 4 main carcinoma types; (7) CK7/CK20 coordinate expression; (8) added value of semiquantitative immunohistochemical stain assessment; algorithmic immunohistochemical approaches to (9) "garden variety" adenocarcinomas presenting in the liver, (10) large polygonal cell adenocarcinomas, (11) the distinction of primary surface ovarian epithelial tumors with mucinous features from metastasis, (12) tumors presenting at alternative anatomic sites, (13) squamous cell carcinoma versus urothelial carcinoma, and neuroendocrine neoplasms, including (14) the distinction of pheochromocytoma/paraganglioma from well-differentiated neuroendocrine tumor, site of origin assignment in (15) well-differentiated neuroendocrine tumor and (16) poorly differentiated neuroendocrine carcinoma, and (17) the distinction of well-differentiated neuroendocrine tumor G3 from poorly differentiated neuroendocrine carcinoma; it concludes with (18) a discussion of diagnostic considerations in the broad-spectrum keratin/CD45/S-100-"triple-negative" neoplasm.

An Update on the Role of Immunohistochemistry in the Evaluation of Gastrointestinal Tract Disorders

As in other organ systems, immunohistochemistry (IHC) serves as an ancillary diagnostic tool for a wide variety of neoplastic and non-neoplastic disorders, including infections, work-up of inflammatory conditions, and subtyping neoplasms of the gastrointestinal (GI) tract. In addition, IHC is also used to detect a variety of prognostic and predictive molecular biomarkers for carcinomas of the GI tract. The purpose of this review is to highlight the use of IHC in common diagnostic scenarios throughout the tubular GI tract. The clinical indication and guidelines for performing IHC for detecting Helicobacter pylori is discussed along with role of gastrin and neuroendocrine markers in the diagnosis of autoimmune metaplastic atrophic gastritis. The major portion of this review discusses the use of IHC in the diagnostic workup of malignant neoplasms of the GI tract, such as adenocarcinoma versus squamous cell carcinoma, workup of poorly differentiated malignant neoplasms, and evaluation of uncommon gastric neoplasms (alpha-feto protein-producing carcinomas) and switch/sucrose-nonfermenting complex-deficient carcinomas. Lastly, localization of neuroendocrine tumors of unknown origin to aid clinical management, as well as HPV-driven anal neoplasia and IHC in the workup of basaloid anal neoplasms are also reviewed.

Pathologic Considerations in Gastroenteropancreatic Neuroendocrine Tumors

This review serves as a primer on contemporary neuroendocrine neoplasm classification, with an emphasis on gastroenteropancreatic well-differentiated neuroendocrine tumors. Topics discussed include general features of neuroendocrine neoplasms, general neuroendocrine marker immunohistochemistry, the distinction of well-differentiated neuroendocrine tumor from pheochromocytoma/paraganglioma and other diagnostic mimics and poorly differentiated neuroendocrine carcinoma from diagnostic mimics, the concepts of differentiation and grade and the application of Ki-67 immunohistochemistry to determine the latter, the various WHO classifications of neuroendocrine neoplasms including the 2019 WHO classification of gastroenteropancreatic tumors, organ-specific considerations for gastroenteropancreatic well-differentiated neuroendocrine tumors, immunohistochemistry to determine site of origin in metastatic well-differentiated neuroendocrine tumor of occult origin, immunohistochemistry in the distinction of well-differentiated neuroendocrine tumor G3 from large cell neuroendocrine carcinoma, and, finally, required and recommended reporting elements for biopsies and resections of gastroenteropancreatic neuroendocrine epithelial neoplasms.

Significance of achaete-scute complex homologue 1 (ASCL1) in pulmonary neuroendocrine carcinomas; RNA sequence analyses using small cell lung cancer cells and Ascl1-induced pulmonary neuroendocrine carcinoma cells

ASCL1 is one of the master transcription factors of small cell lung carcinoma (SCLC). To investigate the significance of ASCL1 in pulmonary neuroendocrine carcinoma, we performed 2 comparative RNA-seq studies between H69 (ASCL1-positive, classical type SCLC) and H69AR (ASCL1-negative, variant type SCLC) and between ASCL1-transfected A549 adenocarcinoma cell lines (A549(ASCL1+) cell lines) and A549(control) cell lines. RNA-seq analyses revealed that 940 genes were significantly different between the H69 and H69AR cell lines, and 728 between the A549(ASCL1+) and A549(control) cell lines. In total, 120 common genes between these analyses were selected as candidate ASCL1-related genes, and included genes with various cellular functions, such as neural development, secretion, growth, and morphology. Their expression degrees in three classical and two variant SCLC cell lines, two A549(ASCL1+) and two A549(control) cell lines were subjected to quantitative PCR analyses. Since the candidate ASCL1-related genes were strongly expressed in the classical SCLC and A549(ASCL1+) cell lines and more weakly expressed in the variant SCLC and A549(control) cell lines, the ASCL1-related 7 molecules INSM1, ISL1, SYT4, KCTD16, SEZ6, MS4A8, and COBL were further selected. These molecules suggested diverse functions for A549(ASCL1+): INSM1 and ISL1 are transcription factors associated with neuroendocrine differentiation, while SYT4, KTCD16, and SEZ6 may be related to neurosecretory functions and MS4A8 and COBL to cell growth and morphology. An immunohistochemistry of these seven molecules was performed on lung carcinoma tissues and the xenotransplanted tumors of A549(ASCL1+), and they were preferentially and positively stained in ASCL1-postive tumor tissues.

The Role of ISL1 and LHX5 LIM Homeobox Genes in Bladder Tumourigenesis

Introduction

Lin-11, Isl-1 and Mec-3 domains (LIM) homeobox genes are among the most important sub-families of homeobox genes. These genes are thought to play an important role in cancer. In this study, the protein expression of these genes was examined in urothelial carcinoma of the bladder. The expression pattern of Islet-1 (ISL1) and LIM homeobox 5 (LHX5) across different cancer stages and grades, as well as the association between the protein expression of these genes and patient demographics and clinicopathological features, were examined.

Methods

A total of 100 formalin-fixed paraffin-embedded urothelial carcinoma tissues were selected from the Department of Pathology, Hospital Kuala Lumpur and the protein expression of ISL1 and LHX5 was determined using immunohistochemistry.

Results

Positive expression of ISL1 and LHX5 was detected in 94% and 98% of the samples, respectively. There were no distinct LHX5 expression patterns associated with different cancer stages, but the proportion of high-expressing tumours was higher in high-grade tumours. In addition, there was a significant association between the expression of LHX5 and tumour grade. The proportion of tumours expressing high levels of ISL1 was found to be highest in later stage tumours.

Conclusion

The high percentage of tumours expressing both these genes suggests that ISL1 and LHX5 play an important role in bladder tumourigenesis across multiple stages.

Immunohistochemistry in the diagnosis and classification of neuroendocrine neoplasms: what can brown do for you?

This review is based on a presentation given at the Hans Popper Hepatopathology Society companion meeting at the 2019 United States and Canadian Academy of Pathology Annual Meeting. It presents updates on the diagnosis and classification of neuroendocrine neoplasms, with an emphasis on the role of immunohistochemistry. Neuroendocrine neoplasms often present in liver biopsies as metastases of occult origin. Specific topics covered include 1. general features of neuroendocrine neoplasms, 2. general neuroendocrine marker immunohistochemistry, with discussion of the emerging marker INSM1, 3. non-small cell carcinoma with (occult) neuroendocrine differentiation, 4. the WHO Classification of neuroendocrine neoplasms, with discussion of the 2019 classification of gastroenteropancreatic neoplasms, 5. use of Ki-67 immunohistochemistry, 6. immunohistochemistry to assign site of origin in neuroendocrine metastasis of occult origin, 7. immunohistochemistry to distinguish well-differentiated neuroendocrine tumor G3 from poorly differentiated neuroendocrine carcinoma, 8. lesions frequently misdiagnosed as well-differentiated neuroendocrine tumor, and 9. required and recommended data elements for biopsies and resections with associated immunohistochemical stains. Next-generation immunohistochemistry, including lineage-restricted transcription factors (e.g., CDX2, islet 1, OTP, SATB2) and protein correlates of molecular genetic events (e.g., p53, Rb), is indispensable for the accurate diagnosis and classification of these neoplasms.

Histogenesis of Merkel Cell Carcinoma: A Comprehensive Review

Merkel cell carcinoma (MCC) is a primary neuroendocrine carcinoma of the skin. This neoplasia features aggressive behavior, resulting in a 5-year overall survival rate of 40%. In 2008, Feng et al. identified Merkel cell polyomavirus (MCPyV) integration into the host genome as the main event leading to MCC oncogenesis. However, despite identification of this crucial viral oncogenic trigger, the nature of the cell in which MCC oncogenesis occurs is actually unknown. In fact, several hypotheses have been proposed. Despite the large similarity in phenotype features between MCC tumor cells and physiological Merkel cells (MCs), a specialized subpopulation of the epidermis acting as mechanoreceptor of the skin, several points argue against the hypothesis that MCC derives directly from MCs. Alternatively, MCPyV integration could occur in another cell type and induce acquisition of an MC-like phenotype. Accordingly, an epithelial as well as a fibroblastic or B-cell origin of MCC has been proposed mainly based on phenotype similarities shared by MCC and these potential ancestries. The aim of this present review is to provide a comprehensive review of the current knowledge of the histogenesis of MCC.

Neuroendocrine Liver Metastasis-a Specific Set of Markers to Detect Primary Tumor Sites

The diagnosis of neuroendocrine neoplasia (NEN) is often made at an advanced stage of disease, including hepatic metastasis. At this point, the primary may still be unknown and sometimes cannot even be detected by functional imaging, especially in very small tumors of the pancreas (pan) and small intestinal (si) entities. The site of the primary may be based on biopsy specimens of the liver applying a specific set of markers. Specimens of liver metastases from 87 patients with NENs were studied. In retrospect, 50 patients had si and 37 pan NENs. Tissue samples were evaluated by immunohistochemistry. The markers applied were insulin gene enhancer protein Islet-1 (ISL-1), homeobox protein CDX-2 (CDX2), thyroid transcription factor 1 (TTF-1), and serotonin. Positive stains for CDX2 were documented in 43 (86%) and for serotonin in 45 (90%) of 50 siNENs. Three panNENs were positive for CDX2 and one for serotonin, respectively. ISL-1 was negative throughout in siNENs and also negative in 8 of 50 panNENs (21.6%). TTF-1 was negative in more than 90% of the specimens of either entity. Immunohistochemical markers in liver metastasis can lead the way to the site of the primary NEN. They should always be used in combined clusters.

ISL1 predicts poor outcomes for patients with gastric cancer and drives tumor progression through binding to the ZEB1 promoter together with SETD7

ISL1, a LIM-homeodomain transcription factor, serves as a biomarker of metastasis in multiple tumors. However, the function and underlying mechanisms of ISL1 in gastric cancer (GC) have not been fully elucidated. Here we found that ISL1 was frequently overexpressed in GC FFPE samples (104/196, 53.06%), and associated with worse clinical outcomes. Furthermore, the overexpression of ISL1 and loss-of-function of ISL1 influenced cell proliferation, invasion and migration in vitro and in vivo, including GC patient-derived xenograft models. We used ChIP-seq and RNA-seq to identify that ISL1 influenced the regulation of H3K4 methylation and bound to ZEB1, a key regulator of the epithelial–mesenchymal transition (EMT). Meanwhile, we validated ISL1 as activating ZEB1 promoter through influencing H3K4me3. We confirmed that a complex between ISL1 and SETD7 (a histone H3K4-specific methyltransferase) can directly bind to the ZEB1 promoter to activate its expression in GC cells by immunoprecipitation, mass spectrometry, and ChIP-re-ChIP. Moreover, ZEB1 expression was significantly positively correlated with ISL1 and was positively associated with a worse outcome in primary GC specimens. Our paper uncovers a molecular mechanism of ISL1 promoting metastasis of GC through binding to the ZEB1 promoter together with co-factor SETD7. ISL1 might be a potential prognostic biomarker of GC.

Grading of Neuroendocrine Carcinomas: Correlation of 68Ga-PET/CT Scan with Tissue Biomarkers

There is a growing need for more accurate biomarkers to facilitate the diagnosis and prognosis of patients with grade (G) 3 neuroendocrine carcinomas (NECs). In particular, the discrimination between well-differentiated neuroendocrine carcinomas (WD-NECs) and poorly differentiated neuroendocrine carcinomas (PD-NECs) is still an unmet need. We previously showed that ⁶⁸Gallium-(⁶⁸Ga-) PET/CT positivity is a prognostic factor in patients with gastroenteropancreatic (GEP) G3 NECs, correlating with a better outcome in terms of overall survival. Here, we hypothesize that ⁶⁸Ga-PET/CT could help to discriminate between WD-NECs and PD-NECs, adding complementary information to that obtained from morphologic and biologic factors. A retrospective, single-institution study was performed on 11 patients with histologically confirmed, measurable G3 large- or small-cell GEP-NECs according to the 2017 WHO classification. The staging procedures included a ⁶⁸Ga-PET/CT scan. Results of ⁶⁸Ga-PET/CT were correlated in univariate analysis with loss of tissue immunohistochemical expression of DAXX/ATRX or RB1 frequently associated with WD-NECs or PD-NECs, respectively. None of the patients with positive ⁶⁸Ga-PET/CT showed loss of RB1 expression, whereas among those (n = 6) with negative ⁶⁸Ga-PET/CT, 4 showed loss of expression. A trend towards a correlation between loss of RB1 expression and negative ⁶⁸Ga-PET/CT was observed. Our preliminary data support the hypothesis that PD-NECs carrying RB1 mutation and loss of its expression may be associated with negative ⁶⁸Ga-PET/CT. If confirmed in a larger clinical trial, ⁶⁸Ga-PET/CT would help in the stratification of G3 NECs.

Histopathological, immunohistochemical, genetic and molecular markers of neuroendocrine neoplasms

Neuroendocrine neoplasms (NENs) arise from cells of the neuroendocrine system located in many sites amongst which most common are the gastrointestinal (GI) system and the lung. The efforts to assess the specific site of origin or predict the biological behavior of NENs is based upon a detailed study of neoplasm's architectural pattern, immunohistochemical, genetic and molecular profile. Immunohistochemistry is used to characterize the aggressivity of NENs, by assessing the proliferation index Ki-67, as well as the neuroendocrine differentiation by assessing chromogranin A (CgA) and CD56. Basal panels of immunohistochemical markers such as CDX-2, Isl-1, TTF-1, PAX6/8 are currently being used to allocate the neoplasms, while in dubious cases new markers are investigating. Unraveling the genetic and molecular mechanisms of NENs pathogenesis along with shedding light on the molecular heterogeneity of neoplasms and the individual patterns of molecular lesions, underlining these neoplasms may provide new tools in terms of diagnostics and therapeutics. Molecular targeted therapies (MTTs) such as everolimus and sunitinib have been the first example of druggable molecular targets implicated in NENs that have been approved for NEN treatment. New investigational drugs are developing along with genetic tests that may allow the identification of the specific subset of patients that will respond to each individual MTT. Multiparametrical molecular and genetic analysis such as the NETest and the MASTER are already in trials shedding light in a step-by-step management of NENs that allow not only the selection of an appropriate therapeutic option but also the identification of response to treatment or early relapse allowing an early amendment of the strategy. Summarizing the combination of histopathological, immunohistochemical, genetic and molecular profile of a NEN opens new horizons in the efficient management of NENs.

NKX2.2, PDX-1 and CDX-2 as potential biomarkers to differentiate well-differentiated neuroendocrine tumors

Background

Well-differentiated neuroendocrine tumors (NET) most frequently arise from the gastrointestinal tract (GI), pancreas, and lung. Patients often present as metastasis with an unknown primary, and the clinical management and outcome depend on multiple factors, including the accurate diagnosis with the tumor primary site. Determining the site of the NET with unknown primary remains challenging. Many biomarkers have been investigated in primary NETs and metastatic NETs, with heterogeneous sensitivity and specificity observed.

Methods

We used high-throughput tissue microarray (TMA) and immunohistochemistry (IHC) with antibodies against a panel of transcriptional factors including NKX2.2, PDX-1, PTF1A, and CDX-2 on archived formalin-fixed paraffin-embedded NETs, and investigated the protein expression pattern of these transcription factors in 109 primary GI (N = 81), pancreatic (N = 17), and lung (N = 11) NETs.

Results

Differential expression pattern of these markers was observed. In the GI and pancreatic NETs (N = 98), NKX2.2, PDX-1, and CDX-2 were immunoreactive in 82 (84%), 14 (14%), and 52 (52%) cases, respectively. PDX-1 was expressed mainly in the small intestinal and appendiceal NETs, occasionally in the pancreatic NETs, and not in the colorectal NETs. All three biomarkers including NKX2.2, PDX-1, and CDX-2 were completely negative in lung NETs. PTF1A was expressed in all normal and neuroendocrine tumor cells.

Conclusions

Our findings suggest that NKX2.2 was a sensitive and specific biomarker for the GI and pancreatic neuroendocrine tumors. We proposed that a panel of immunostains including NKX2.2, PDX-1, and CDX-2 may show diagnostic utility for the most common NETs.

Pathology of Neuroendocrine Tumours of the Female Genital Tract

Neuroendocrine tumours are uncommon or rare at all sites in the female genital tract. The 2014 World Health Organisation (WHO) Classification of neuroendocrine tumours of the endometrium, cervix, vagina and vulva has been updated with adoption of the terms low-grade neuroendocrine tumour and high-grade neuroendocrine carcinoma. In the endometrium and cervix, high-grade neoplasms are much more prevalent than low-grade and are more common in the cervix than the corpus. In the ovary, low-grade tumours are more common than high-grade carcinomas and the term carcinoid tumour is still used in WHO 2014. The term ovarian small-cell carcinoma of pulmonary type is included in WHO 2014 for a tumour which in other organs is termed high small-cell neuroendocrine carcinoma. Neuroendocrine tumours at various sites within the female genital tract often occur in association with other neoplasms and more uncommonly in pure form.

Islet-1 promotes the proliferation and invasion, and inhibits the apoptosis of A375 human melanoma cells

The aim of this study was to examine the effects of the insulin gene enhancer-binding protein, islet-1 (ISL1), on the proliferation, invasion and apoptosis of the human melanoma cell line, A375. An ISL1 overexpression lentiviral vector was constructed and transfected into the A375 cells. The proliferation of the A375 cells transfected with the ISL1 vector (termed A375/ISL1 cells) was examined by MTT assay, flow cytometry and TUNEL assay, and cell invasion was examined by Transwell assay. The expression levels of matrix metalloproteinase (MMP)-2 and MMP-9 were measured by qPCR and western blot analysis; the expression levels of Akt and p-Akt were measured in the cells treated with vascular endothelial growth factor (VEGF) and the PI3K/Akt inhibitor, LY294002, by western blot analysis. The optical density value of the A375/ISL1 cells was increased after 12 h of culture (P<0.001), as shown by MTT assay. The ratio of apoptotic A375/ISL1 cells was significantly decreased (P<0.001), as shown by flow cytometry and TUNEL assay. In addition, the average penetration rate of the A375/ISL1 cells significantly increased (P<0.001), as shown by Transwell assay. The expression levels of MMP-2 and MMP-9 were significantly increased in the A375/ISL1 cells, as shown by qPCR and western blot analysis (P<0.001). Moreover, treatment of the A375/ISL1 cells with VEGF for 48 h increased the expression of Akt and p-Akt compared with the control cells transfected with A375/green fluorescent protein (GFP) (P<0.05; P<0.001, respectively). In addition, in the A375/ISL1 cells treated with the LY294002 inhibitor for 24 and 48 h, the level of Akt was also found to increase compared to the control A375/GFP cells (P<0.05). On the whole, the findings of this study indicate that the overexpression of ISL1 promotes the proliferation and invasion, and inhibits the apoptosis of A375 melanoma cells. ISL1 thus plays an important role in A375 cell survival, and these effects are possibly mediate via the PI3K/Akt signaling pathway.

Discovering cancer vulnerabilities using high-throughput micro-RNA screening

Micro-RNAs (miRNAs) are potent regulators of gene expression and cellular phenotype. Each miRNA has the potential to target hundreds of transcripts within the cell thus controlling fundamental cellular processes such as survival and proliferation. Here, we exploit this important feature of miRNA networks to discover vulnerabilities in cancer phenotype, and map miRNA-target relationships across different cancer types. More specifically, we report the results of a functional genomics screen of 1280 miRNA mimics and inhibitors in eight cancer cell lines, and its presentation in a sophisticated interactive data portal. This resource represents the most comprehensive survey of miRNA function in oncology, incorporating breast cancer, prostate cancer and neuroblastoma. A user-friendly web portal couples this experimental data with multiple tools for miRNA target prediction, pathway enrichment analysis and visualization. In addition, the database integrates publicly available gene expression and perturbation data enabling tailored and context-specific analysis of miRNA function in a particular disease. As a proof-of-principle, we use the database and its innovative features to uncover novel determinants of the neuroblastoma malignant phenotype.

INSM1 Demonstrates Superior Performance to the Individual and Combined Use of Synaptophysin, Chromogranin and CD56 for Diagnosing Neuroendocrine Tumors of the Thoracic Cavity

Despite the importance of recognizing neuroendocrine differentiation when diagnosing tumors of the thoracic cavity, the sensitivity of traditional neuroendocrine markers is suboptimal, particularly for high-grade neuroendocrine carcinomas such as small cell lung carcinoma and large cell neuroendocrine carcinoma. To increase sensitivity, neuroendocrine markers are routinely ordered as panels of multiple immunostains where any single positive marker is regarded as sufficient evidence of neuroendocrine differentiation. Insulinoma-associated protein 1 (INSM1) is a well-validated transcription factor of neuroendocrine differentiation that has only recently been evaluated for diagnostic use. We performed INSM1 immunohistochemistry on a large series of thoracic neuroendocrine and non-neuroendocrine tumors and compared its performance to synaptophysin, chromogranin, and CD56. INSM1 was positive in 94.9% of small cell lung carcinomas and 91.3% of large cell neuroendocrine carcinomas, compared with 74.4% and 78.3% with the combined panel of traditional markers. INSM1 also stained all (100%) of the atypical carcinoids, typical carcinoids and mediastinal paragangliomas, but only 3.3% of adenocarcinomas and 4.2% of squamous cell carcinomas. Overall, INSM1 demonstrated a sensitivity of 96.4% across all grades of thoracic neuroendocrine tumors, significantly more than the 87.4% using the panel of traditional markers (P=0.02). INSM1 is sufficiently sensitive and specific to serve as a standalone first-line marker of neuroendocrine differentiation. A more restrained approach to immunohistochemical analysis of small thoracic biopsies is appropriate given the expanding demand on this limited material for therapeutic biomarker analysis.

Neuroendocrine Neoplasms: Dichotomy, Origin and Classifications

Neuroendocrine neoplasms (NENs) are heterogeneous tumors with a common phenotype. There are two fundamentally different groups of NENs: well-differentiated, low-proliferating NENs, called neuroendocrine tumors (NETs) or carcinoids, and poorly differentiated, highly proliferating NENs, called small- or large-cell neuroendocrine carcinomas (NECs). This NEN dichotomy is probably due to an origin from different neuroendocrine progenitor cells. The current World Health Organization (WHO) classification of gastrointestinal NENs uses the Ki67 proliferation index to grade NETs as G1 or G2, and NECs as G3. In the pancreas, NETs and NECs may overlap in their proliferation index, making the distinction between them difficult and leading to therapeutic uncertainties. Therefore, the WHO classification of pancreatic NENs (PanNENs) from 2017 introduced a new NET G3 category. Helpful for the distinction of NETs G3 from NECs is the expression of p53 and rb1 that is usually negative in PanNETs. Comparison of the WHO classification of digestive system NENs with other NEN classifications reveals site-specific differences in terminology and a general lack of grading systems. However, all classifications recognize the existence of the two major NEN families and provide a general basis for their prognostic and therapeutic stratification. A development of a common NEN classification across organs is desirable.

Classification of pulmonary neuroendocrine tumors: new insights

Neuroendocrine tumors of the lung (Lu-NETs) embrace a heterogeneous family of neoplasms classified into four histological variants, namely typical carcinoid (TC), atypical carcinoid (AC), large cell neuroendocrine carcinoma (LCNEC) and small cell lung carcinoma (SCLC). Defining criteria on resection specimens include mitotic count in 2 mm2 and the presence or absence of necrosis, alongside a constellation of cytological and histological traits including cell size and shape, nuclear features and overall architecture. Clinically, TC are low-grade malignant tumors, AC intermediate-grade malignant tumors and SCLC/LCNEC high-grade malignant full-blown carcinomas with no significant differences in survival between them. Homologous tumors arise in the thymus that occasionally have some difficulties in differentiating from the lung counterparts when presented with large unresectable or metastatic lesions. Immunohistochemistry (IHC) helps refine NE diagnosis at various anatomical sites, particularly on small-sized tissue material, in which only TC and small cell carcinoma categories can be recognized easily on hematoxylin & eosin stain, while AC and LCNEC can only be suggested on such material. The Ki-67 labeling index effectively separates carcinoids from small cell carcinoma and may prove useful for the clinical management of a metastatic disease to help the therapeutic decision-making process. Although carcinoids and high-grade neuroendocrine carcinomas in the lung and elsewhere make up separate tumor categories on molecular grounds, emerging data supports the concept of secondary high-grade NETs arising in the preexisting carcinoids, whose clinical and biological relevance will have to be placed into the proper context for the optimal management of these patients. In this review, we will discuss the selected, recent literature with a focus on current issues regarding Lu-NET nosology, i.e., classification, derivation and tumor evolution.

High-grade Neuroendocrine Carcinoma of the Lung With Carcinoid Morphology: A Study of 12 Cases

Twelve lung neuroendocrine tumors with morphologic features of carcinoid tumors but with mitotic count >10/2 mm are reported. There were 7 males and 5 females, with age ranging from 56 to 78 years. Four cases were from never-smokers. All tumors showed architectural and cytomorphologic features of carcinoid tumor, including organoid nesting, insular, trabecular, or acinar growth, and tumor cells with low nucleocytoplasmic ratio, abundant cytoplasm, ovoid to round nuclei, and salt and pepper chromatin. Angulated or confluent nesting, insular or lobular growth pattern was also seen. Nuclear irregularities and anisonucleosis were focally present. Mitotic count ranged from 11 to 61/2 mm. Punctate-type necrosis was present in 8 tumors. Anaplastic cytology, large infarct-type necrosis, desmoplasia, or marked inflammatory infiltrate was not found in any of the tumors. One tumor occurred in the background of diffuse idiopathic pulmonary neuroendocrine hyperplasia. All tumors were treated by resection, and all but 1 patient subsequently developed metastasis, and 7 died of the tumor. For metastatic tumors, 4 patients were treated by platinum-based chemotherapy with no apparent response, whereas 3 other patients were treated by combined capecitabine and temozolomide-novel chemotherapy for well-differentiated neuroendocrine tumor/carcinoid tumor-2 of them responded. This subset of tumor would be classified as large cell neuroendocrine carcinoma according to the current WHO classification scheme, but their clinical and pathologic features appear to have more in common with the carcinoid tumor group than large cell neuroendocrine carcinoma, therefore, identification of this subset may be relevant for further therapeutic management.