Insulinoma-associated Protein 1 Research Articles

Cytological diagnosis of olfactory neuroblastoma at metastatic sites, with emphasis on role of insulinoma-associated protein 1 immunocytochemistry.

Olfactory neuroblastoma (ONB) is a rare neuroectodermal tumor with a propensity for lymph node and distant metastases in a proportion of cases, presenting opportunities for cytological diagnosis. Insulinoma-associated protein 1 (INSM1) is a recently identified marker of neuroendocrine differentiation with higher sensitivity and specificity than traditional neuroendocrine immunostains used in diagnosis of ONB. Archival aspirates diagnosed as metastatic ONB were retrieved and reviewed for described characteristics of ONB. Spare direct smears with sufficient cellular material from each case were selected, if available, and immunocytochemistry for INSM1 was performed on the destained alcohol-fixed smears. INSM1 was also performed on non-neuroendocrine malignant round cell tumors (MRCT). Seven fine needle aspirates (FNA) from five patients were identified, all of which showed a small round cell tumor with fine to coarse granular chromatin. Most cases had moderate to high cellularity, comprised of loosely cohesive clusters and dispersed cells. While two-cell pattern, nuclear streaking and moulding were frequent, background neuropil, fibrillary cytoplasm, and rosettes were uncommon. INSM1 immunostaining performed on spare direct smears showed strong positivity in 30%-100% of tumor cells (mean: 62%) in all aspirates tested (100%). In comparison with other immunostains, INSM1 showed more robust staining, and was easier to interpret. All non-neuroendocrine MRCTs were negative for INSM1. Metatstatic ONB can resemble other small round cell tumors, as all the diagnostic features of ONB may not be readily evident. INSM1 immunocytochemistry has high sensitivity and specificity and can reliably be used as a single marker to support the cytomorphology for a confirmatory diagnosis of ONB, even on direct smears if a cell block is not available.

Co-Expression of Adaptor Protein FAM159B with Different Markers for Neuroendocrine Cells: An Immunocytochemical and Immunohistochemical Study.

Little is known about the adaptor protein FAM159B. Recently, FAM159B was shown to be particularly expressed in neuroendocrine cells and tissues, such as pancreatic islets and neuroendocrine cells of the bronchopulmonary and gastrointestinal tracts, as well as in different types of neuroendocrine tumours. To gain insights into possible interactions of FAM159B with other proteins and/or receptors, we analysed the co-expression of FAM159B and various neuroendocrine-specific markers in the cancer cell lines BON-1, PC-3, NCI-h82, OH-1, and A431 and also in human pancreatic tissues and pancreatic neuroendocrine tumours. The markers included prominent markers of neuroendocrine differentiation, such as chromogranin A (CgA), neuron-specific enolase (NSE), synaptophysin (SYP), insulinoma-associated protein 1 (INSM1), neural cell adhesion molecule 1 (NCAM1), serotonin (5-HT), somatostatin-14/28 (SST), and several receptors that are typically expressed by neuroendocrine cells, such as dopamine receptor 2 (D2R), somatostatin receptor (SSTR) 1, 2, 3, 4 and 5, and regulator of G-protein signalling 9 (RGS9). FAM159B was expressed evenly throughout the cytosol in all five cancer cell lines. Immunocytochemical and immunohistochemical analyses revealed co-expression of FAM159B with SYP, INSM1, RGS9, D2R, SSTR2, SSTR3, SSTR4, and SSTR5 and strong overlapping co-localisation with NSE. Double-labelling and co-immunoprecipitation Western blot analyses confirmed a direct association between FAM159B and NSE. These results suggest the involvement of FAM159B in several intracellular signalling pathways and a direct or indirect influence on diverse membrane proteins and receptors.

Insulinoma-Associated Protein 1 (INSM1): Diagnostic, Prognostic, and Therapeutic Use in Small Cell Lung Cancer

Small cell lung carcinoma (SCLC) is an aggressive and difficult to treat cancer. Although immunohistochemistry is not mandatory for a SCLC diagnosis, it might be required, especially in small samples. Insulinoma-associated protein 1 (INSM1) is expressed in endocrine and nervous tissues during embryogenesis, generally absent in adults and re-expressed in SCLC and other neuroendocrine neoplasms. Its high specificity propelled its use as diagnostic biomarker and an attractive therapeutic target. Herein, we aim to provide a systematic and critical review on the use of INSM1 for diagnosis, prognostication and the treatment of SCLC. An extensive bibliographic search was conducted in PubMed® focusing on articles published since 2015. According to the literature, INSM1 is a highly sensitive (75–100%) and specific (82–100%) neuroendocrine immunohistochemical marker for SCLC diagnosis. It can be used in histological and cytological samples. Although advantageous, its standalone use is currently not recommended. Studies correlating INSM1 expression and prognosis have disclosed contrasting results, although the expression seemed to entail a worse survival. Targeting INSM1 effectively suppressed SCLC growth either as a suicide gene therapy regulator or as an indirect target of molecular-targeted therapy. INSM1 represents a valuable biomarker for a SCLC diagnosis that additionally offers vast opportunities for the development of new prognostic and therapeutic strategies.

Abstract 5252: In colorectal cancer (CRC), neuroendocrine carcinoma (NEC) is contaminated in the cancer given a confirmed diagnosis of poorly differentiated adenocarcinoma (P-ad-ca)

Abstract Background: Most of CRC were well or moderately differentiated adenocarcinoma and P-ad-ca is very rare. In Japan, P-ad-ca was reported to be only 4-6% of all CRC. NEC is also rare. The incidence of that were reported to be less than 1%. One of their points of common is morphological poorly differentiated appearance. In this study, we evaluated the incidence of NEC contaminated in the CRC given a confirmed diagnosis as P-ad-ca. Material and Method: From 2009 to 2019, 816 CRCs were resected in department of Yokohama City University Hospital and 74 cases showing P-ad-ca or having a small region of P-ad-ca with well or moderately differentiated ad-ca (W-ad-ca, M-ad-ca). Among the 74 cases, there were 8 of P-ad-ca, 4 of W-ad-ca with P-ad-ca, 44 of M-ad-ca with P-ad-ca, and 18 W-ad-ca and M-ad-ca with P-ad-ca. Immunohistochemistry (IHC) using neuroendocrine markers (NM) including chromogranin A, synaptophysin and insulinoma-associated protein 1 (INSM1) was performed to identified NEC. Recently, a high incidence of Rb protein loss was reported in NEC of several organs, then IHC using Rb monoclonal antibody was also performed. The cancers showing immunohistochemically positive of at least one of the three NM and negative of Rb were identified as true NEC in this study. Results: At least one of the three NM was positive in the 39 cases. In these 39 cases, 3 cases were also Rb negative. Two of the three cases were region of P-ad-ca. These 2 P-ad-ca regions showed positive of NM. Interestingly, in the other one case, region of W-ad-ca showed positive of NM and negative of Rb. Region of P-ad-ca of the case showed positive of all three NM and Rb. From morphological appearance, this case was quite unlikely to true NEC. Conclusion: In 74 P-ad-ca, 2 cases might be true NEC in our small evaluation. NEC might be contaminated in the P-ad-ca of CRC which is difficult to be distinguished by only pathological findings of HE staining. Citation Format: Yuhan Rong, Yuma Takeda, Naoki Okubo, Akihiro Suzuki, Motohiko Tokuhisa, Noritoshi Kobayashi, Atsushi Ishibe, Ikuma Kato, Shoji Yamanaka, Satoshi Fujii, Itaru Endo, Yasushi Ichikawa. In colorectal cancer (CRC), neuroendocrine carcinoma (NEC) is contaminated in the cancer given a confirmed diagnosis of poorly differentiated adenocarcinoma (P-ad-ca) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5252.

Pulmonary Neuroendocrine Cells and Small Cell Lung Carcinoma: Immunohistochemical Study Focusing on Mechanisms of Neuroendocrine Differentiation.

Neuroendocrine (NE) differentiation has been histochemically detected in normal and cancer tissues and cells. Immunohistochemical analyses have provided a more detailed understanding of NE biology and pathology. Pulmonary NE cells are a rare lung epithelial type, and small cell carcinoma of the lung (SCLC) is a high-grade NE tumor. Pulmonary NE and SCLC cells share common mechanisms for NE differentiation. Neural or NE cell lineage-specific transcription factors, such as achaete-scute homologue 1 (Ascl1) and insulinoma-associated protein 1 (INSM1), are crucial for the development of pulmonary NE cells, and NE differentiation is influenced by the balance between Ascl1 and the suppressive neural transcription factor, hairy-enhancer of split 1, a representative target molecule of the Notch signaling pathway.In this review, we discuss the importance of Ascl1 and INSM1 in identifying pulmonary NE and SCLC cells and introduce Ascl1-related molecules detected by comparative RNA-sequence analyses. The molecular classification of SCLC based on the expression of lineage-specific transcription or co-transcription factors, including ASCL1, NEUROD1, POU2F3, and YAP1, was recently proposed. We attempted to characterize these 4 SCLC subtypes using integrated immunohistochemical studies, which will provide insights into the molecular characteristics of these subtypes and clarify the inter- and intratumor heterogeneities of SCLC.

Diagnostic evaluation of selected granin family proteins and INSM-1 (Insulinoma-associated protein 1) in patients with medullary thyroid carcinoma

Diagnostic evaluation of selected granin family proteins and INSM-1 (Insulinoma-associated protein 1) in patients with medullary thyroid carcinoma

Granin family peptides and INSM-1 (Insulinoma-associated protein 1) in the biochemical diagnosis of pheochromocytoma

Granin family peptides and INSM-1 (Insulinoma-associated protein 1) in the biochemical diagnosis of pheochromocytoma

Utility of Secretagogin as a Novel Marker for the Diagnosis of Lung Neuroendocrine Carcinoma

BackgroundSmall cell lung cancers (SCLC) and large cell neuroendocrine carcinomas (LCNEC) are a subset of high‐grade lung carcinomas with characteristic morphology and molecular profile. Commonly used neuroendocrine markers include synaptophysin, chromogranin A, CD56, and insulinoma‐associated protein 1 (INSM1). However, none of these neuroendocrine markers are perfectly sensitive nor specific. Thus, we examined the utility of a calcium‐binding protein, secretagogin (SCGN), which is found mainly in neuroendocrine cells and neurons for diagnosing high‐grade neuroendocrine carcinomas (NECs) of the lung.Materials and MethodsA total of 71 pulmonary NEC resection specimens were collected from the pathology archive between 2005 and 2021, including 18 SCLCs, 13 combined‐SCLCs (c‐SCLCs), 23 LCNECs, and 17 combined‐LCNECs (c‐LCNECs). Immunohistochemical stains with SCGN were done and compared with synaptophysin, chromogranin A, CD56, and INSM1. The stains were evaluated by Allred scoring system which combined staining intensity and proportion of positive tumor cells. Both intensity score (none =0, mild =1, moderate =2, strong =3) and proportion score (0% =0, <1% =1, 1‐10% =2, 11‐33% =3, 34‐66% =4, 67‐100% =5) were summed up to give a final Allred score between 0 and 8. At least mild staining intensity in at least 1% of the cells was considered positive (Allred score greater than or equal to 2). Clinicopathological parameters such as age, sex, smoking history, tumor size, and tumor stage were also retrieved from the medical chart. Paired T‐test (two‐sided) was used to compare the Allred scores and positive proportions of each stain. Fisher’s exact test was used for categorical variables. A P‐value less than 0.05 was considered statistically significant.ResultsBioinformatic study showed the specific SCGN expression in neuroendocrine cells and NECs. No significant difference was observed among the four NEC categories regarding age, sex, tumor size, and staging. All patients had a history of smoking. SCGN showed diffuse nuclear and cytoplasmic staining in NECs with intra‐tumoral heterogenicity (Figure 1). The non‐neuroendocrine components were negative for SCGN. Sensitivity of SCGN was no better than the other established neuroendocrine markers based on Allred score for all cases combined or LCNECs/c‐LCNECs only. However, the sensitivity of SCGN (71%) was slightly higher than chromogranin A (68%) based on Allred score for SCLCs/c‐SCLCs only. The average percentage of SCGN positive tumor cells was 8% higher than chromogranin A (22% versus 14%, P=0.0332) in all NECs and 18% higher (32% for SCGN versus 13% for chromogranin A, P=0.0054) for SCLC and c‐SCLC cases only.ConclusionSCGN had the lowest sensitivity (55%) among the markers. However, it performed better than chromogranin A (71% versus 68%) in the diagnosis of SCLCs and c‐SCLCs. Its positive tumor cell percentage was significantly higher than chromogranin A in SCLCs and c‐SCLCs (18% higher, P=0.0054). The above data showed that SCGN could be used as a supplemental neuroendocrine marker to diagnose small cell carcinoma.

Utility of secretagogin as a marker for the diagnosis of lung neuroendocrine carcinoma.

Small-cell lung cancers (SCLC) and large-cell neuroendocrine carcinomas (LCNEC) are two types of high-grade pulmonary neuroendocrine carcinomas (NECs). Diagnostic neuroendocrine markers commonly include synaptophysin, chromogranin A, CD56, and insulinoma-associated protein 1 (INSM1). In this study, the utility of secretagogin (SCGN) was examined in the context of pulmonary NEC diagnosis. The study included 71 pulmonary NEC cases (18 SCLCs, 13 combined-SCLCs, 23 LCNECs, and 17 combined-LCNECs). Immunohistochemical stains of SCGN, synaptophysin, chromogranin A, CD56, and INSM1 were performed on whole tumor sections. The stains were evaluated based on combined staining intensity and the proportion of positive tumor cells. At least mild staining intensity in at least 1% of the cells was considered positive. Bioinformatic studies showed specific SCGN expression in neuroendocrine cells and NECs. SCGN showed diffuse nuclear and cytoplasmic staining in NECs with intra-tumoral heterogeneity. The non-neuroendocrine components were negative. The sensitivity of SCGN was no better than the other established neuroendocrine markers based on all NECs combined or LCNECs/c-LCNECs only. However, the sensitivity of SCGN (71%) was higher than chromogranin A (68%) for SCLCs/c-SCLCs only. The average proportion of SCGN positive tumor cells was 8% higher than chromogranin A (22% versus 14%, P = 0.0332) in all NECs and 18% higher for SCLC and c-SCLC cases only (32% versus 13%, P = 0.0054). The above data showed that SCGN could be used as a supplemental neuroendocrine marker to diagnose SCLC.

Immunohistochemical analyses of the expression profiles of INSM1, ATRX, DAXX and DLL3 in solid papillary carcinomas of the breast.

Solid papillary carcinoma (SPC) is a rare but distinct clinicopathological feature of breast cancer characterised by frequent neuroendocrine differentiation. Insulinoma-associated protein 1 (INSM1) is a useful neuroendocrine marker for various neuroendocrine tumours. α-thalassemia/mental retardation syndrome X-linked protein (ATRX) and death domain-associated protein (DAXX) are useful prognostic markers for patients with pancreatic neuroendocrine tumours. However, to the best of our knowledge, few studies have addressed INSM1 expression in SPCs. Although ATRX, DAXX and δ-like canonical notch ligand 3 (DLL3) are frequently expressed in neuroendocrine lung carcinomas, there are no reports on their expression in SPCs. Therefore, the present study aimed to analyse the expression profiles of INSM1, ATRX, DAXX and DLL3 in the largest series of patients with SPC that has been, to the best of our knowledge, studied until now. Immunohistochemical analyses were performed to determine chromogranin A, synaptophysin, INSM1, ATRX, DAXX and DLL3 expression in 39 specimens surgically resected from patients with SPC (18 SPC in situ and 21 SPC invasive). The associations between the expression of these markers and the clinicopathological factors were investigated. Chromogranin A, synaptophysin and INSM1 were expressed in 64.1, 100 and 92.3% of the patients, respectively. Both ATRX and DAXX expression was observed in 28.2% of the patients. No patient expressed DLL3. Lack of INSM1 or chromogranin A expression was significantly associated with advanced pathological stages in patients with SPC (P=0.033) and in patients with invasive SPC (P=0.012), showing a tendency for a high Ki-67 labelling index (LI) and advanced histological grade in patients with invasive SPC. Loss of ATRX or DAXX expression was significantly associated with lymphatic invasion, but not with histological grade, Ki-67 LI or presence of invasive tumours. Thus, INSM1 was demonstrated to be a useful diagnostic marker for SPCs. Overall, detecting the lack of INSM1 or chromogranin A expression may be useful for analysing the characteristics of tumour cells in SPCs.

SOX11 is a sensitive and specific marker for pulmonary high-grade neuroendocrine tumors

BackgroundSynaptophysin (SYN), chromogranin A (CGA), CD56 and insulinoma-associated protein 1 (INSM1) are proposed neuroendocrine (NE) markers used for diagnosis of pulmonary NE tumors. These NE markers have been identified in subsets of non-NE tumors requiring differential diagnosis, thus we sought to explore new NE markers.MethodsWe evaluated the immunohistochemical expression of SOX11, a transcription factor involved in neurogenesis, in pulmonary NE tumors and large cell carcinomas (LCCs).ResultsWe found that SOX11 showed a sensitivity similar to INSM1 and CGA, and less than SYN and CD56 in small cell lung carcinomas (SCLCs) and large cell neuroendocrine carcinomas (LCNECs). While SOX11 is more specific than the other four markers for diagnosis of high-grade neuroendocrine carcinomas (HG-NECs) because 1) None of LCCs (0/63), the most challenging non-NE tumor type for differential diagnosis due to overlapped morphology with LCNECs displayed SOX11 positivity. While expression of at least one of SYN, CGA, CD56 or INSM1 was identified in approximately 60% (18/30) of LCCs. 2) SOX11 was only expressed in 1 of 37 carcinoid tumors in contrast to diffuse expression of SYN, CGA, CD56 and INSM1. In HG-NECs, we noticed that SOX11 was a good complementary marker for SCLC diagnosis as it was positive in 7 of 18 SYN−/CGA−/CD56− SCLCs and 3 of 8 SYN−/CGA−/CD56−/INSM1− SCLCs, and SOX11 positivity in 4 of 6 SYN−/CGA−/CD56− cases previously diagnosed as LCCs with NE morphology provides additional evidence of NE differentiation for reclassification into LCNECs, which was further confirmed by electromicroscopical identification of neurosecretory granules. We also found SOX11 expression cannot predict the prognosis in patients with HG-NECs.ConclusionsTherefore, SOX11 is a useful complementary transcriptional NE marker for diagnosis and differential diagnosis of SCLC and LCNEC.

Insulinoma-Associated Protein 1 (INSM1) as a Novel Immunohistochemical Marker for Neuroendocrine Neoplasms

Insulinoma-Associated Protein 1 (INSM1) as a Novel Immunohistochemical Marker for Neuroendocrine Neoplasms

INSM1, a Novel Biomarker for Detection of Neuroendocrine Neoplasms: Cytopathologists' View.

Background: Insulinoma-associated protein 1 (INSM1) has been considered as a novel immunostain for neuroendocrine tumors (NETs) and is hypothesized to be more reliable than first-generation NET biomarkers, such as CGA (chromogranin A), SYP (synaptophysin) and CD56 (neural cell adhesion molecule). In this review, we summarize existing literature on INSM1′s reliability as an immunostain for detection of various NETs, its results in comparison to first-generation NET biomarkers, and its expression in both non-NETs and benign tissues/cells on cytology specimens (cell blocks/smears).

Prognostic value and non-neuroendocrine role of INSM1 in small cell lung cancer

BackgroundSmall cell lung cancer (SCLC) is a malignant lung neuroendocrine tumor with early metastasis, rapid progression, and poor outcomes. Insulinoma-associated protein 1 (INSM1) has been an excellent marker for neuroendocrine (NE) differentiation and widely used in the diagnosis of NE neoplasms, including SCLC. However, its role beyond NE diagnostic marker remained little reported. MethodsWe examined immunohistochemical expression of INSM1 in 73 surgically resected SCLC, analyzed its prognostic value by Kaplan-Meier method, and investigated clinical-pathological features of INSM1 high SCLC. In vitro, We assessed INSM1 function on glucose intake, tumor migration, and Cisplatin resistance by 2-NBDG glucose uptake fluorescent assay, transwell assay, and ANNEXIN V/PI assay, respectively. In vivo, we evaluated the therapeutic value of metformin on reversing INSM1 induced chemoresistance by BALB/c nude mice xenograft tumor model. ResultsHigh INSM1 expression was correlated with lymph node metastasis (LNM) (p = 0.0005), later TNM stages (p = 0.0003), and predicted poor survival (Log-rank p = 0.038). Multivariate Cox analysis confirmed INSM1 as an independent prognostic factor in SCLC (p = 0.012, HR:3.195, 95%CI:1.288–7.927). Interestingly, LNM was correlated with worse prognosis only in patients received chemotherapy (Log-rank p = 0.027) rather than the others (Log-rank p = 0.40). In patients having LNM and treated with chemotherapy, high INSM1 was correlated with worse clinic outcome (Log-rank p = 0.009). In vitro, overexpression of INSM1 decreased AMPK-α expression as well as glucose intake, promoted tumor cell migration, and limited the apoptosis induced by Cisplatin, which all could be reversed by Metformin. In vivo, INSM1 overexpression also contributed to tumor growth beyond inducing Cisplatin resistance. ConclusionOur finding suggested INSM1 played more role than a NE marker, partly through down-regulating AMPK signal. INSM1 may serve as a novel prognostic marker and therapeutic target in SCLC.

Syntaxin-1 and Insulinoma-Associated Protein 1 Expression in Breast Neoplasms with Neuroendocrine Features.

Introduction: A subset of breast neoplasia is characterized by features of neuroendocrine differentiation. Positivity for Neuroendocrine markers by immunohistochemistry is required for the diagnosis. Sensitivity and specificity of currently used markers are limited; based on the definitions of WHO Classification of Tumours, 5th edition, about 50% of breast tumors with features of neuroendocrine differentiation express chromogranin-A and 16% express synaptophysin. We assessed the applicability of two novel markers, syntaxin-1 and insulinoma-associated protein 1 (INSM1) in breast carcinomas. Methods: Hypercellular (Type B) mucinous carcinomas, solid papillary carcinomas, invasive carcinomas of no special type with neuroendocrine features and ductal carcinomas in situ of neuroendocrine subtype were included in our study. The immunohistochemical panel included chromogranin A, synaptophysin, CD56, syntaxin-1 and INSM1. The specificity of syntaxin-1 and INSM1 was determined using samples negative for chromogranin A, synaptophysin and CD56. Results: The sensitivity of syntaxin-1 was 84.7% (50/59), with diffuse positivity in more than 60% of the cases. Syntaxin-1 also had an excellent specificity (98.1%). Depending on the definition for positivity, the sensitivity of INSM1 was 89.8% (53/59) or 86.4% (51/59), its specificity being 57.4% or 88.9%. The sensitivities of chromogranin A, synaptophysin and CD56 were 98.3, 74.6 and 22.4%, respectively. Discussion: Syntaxin-1 and INSM1 are sensitive and specific markers of breast tumors with neuroendocrine features, outperforming chromogranin A and CD56. We recommend syntaxin-1 and INSM1 to be included in the routine neuroendocrine immunohistochemical panel.

Expression of CD200 and INSM1 in gastrointestinal and pancreatic neuroendocrine neoplasms and its diagnostic values

Objective: To investigate the expression and diagnostic values of CD200 and insulinoma associated protein 1 (INSM1) in gastrointestinal and pancreatic neuroendocrine neoplasm (GIP-NEN). Methods: The expression of CD200, INSM1, Syn and CgA was detected in 69 cases of GIP-NEN, 66 cases of gastrointestinal and pancreatic non-neuroendocrine neoplasm (GIP-nonNEN) and 16 cases of metastatic neuroendocrine neoplasm by immunohistochemistry, to compare the values of CD200, INSM1, Syn, CgA and their combinations in diagnosing GIP-NEN. Receiver operating characteristics (ROC) curve was used. Results: The immunoreactivity of CD200 was present in the cytoplasma and/or membrane of the neoplasms cells, the positive expression rates in GIP-NEN and GIP-nonNEN were significantly different (P<0.01). The sensitivity and specificity of CD200 for diagnosing GIP-NEN were 95.7% and 78.8%, respectively. There was significant difference of the positive rates of CD200 between neuroendocrine tumor and neuroendocrine carcinoma (P=0.05). The immunoreactivity of INSM1 was present in the nuclei of neoplasms cells. The positive expression rates in GIP-NEN and GIP-nonNEN were significantly different (P<0.01). The sensitivity and specificity of INSM1 for diagnosis of GIP-NEN were 85.5% and 95.5%, respectively. There were also significantly different positive rates of INSM1 between neuroendocrine tumor and neuroendocrine carcinoma, as well as between G1 and G3 neuroendocrine tumors (P<0.05). There was no difference in the area under ROC curve (AUC) of single stain of CD200, INSM1, Syn or CgA (0.857, 0.907, 0.890 and 0.833, respectively, P>0.05). The sensitivity of combined CD200+INSM1 stains for diagnosing GIP-NEN was significantly higher than that of Syn+CgA (85.5% vs. 63.8%, P<0.05). The AUC of two combinations were 0.962 and 0.925, respectively, which were not statistically different (P>0.05). Conclusions: CD200 and INSM1 are two novel markers of neuroendocrine neoplasm, which aid to diagnosis for GIP-NEN and exclude its mimickers. They are associated with tumor grades. Combining both as an immunohistochemical panel shows high sensitivity and specificity. Thus, the combined panel can be utilized as useful supplement for Syn and CgA.

P66.08 Differential Expression of INSM1 Between Pure SCLC and LCNEC After Surgical Resection and Its Clinicopathological Significance

According to WHO diagnostic criteria, both Small cell lung cancer (SCLC) and Large cell neuroendocrine (LCNEC) are categorized into high grade neuroendocrine carcinoma, based on morphological features and immunostaining of neuroendocrine markers including CD56, chromogranin A (CgA) and synaptophysin (Syn). However, the above markers have limited satisfactory significance of specificity and sensitivity. Insulinoma-associated protein 1 (INSM1) is highly expressed in SCLC cells as a zinc finger protein, and numerous studies have shown that INSM1 positive staining has a strong correlation with NE differentiation in SCLC and an alternative diagnostic biomarker for SCLC, but few studies are involved in LCNEC and its significance remains unclear in LCNEC. The aim of this study was to investigate the potential of INSM1 as a neuroendocrine marker by comparing the expression of INSM1 in SCLC and LCNEC and its clinicopathological significance. 347 surgically resected lung cancer including 290 pure SCLC and 57 pure LCNEC samples were retrieved in this retrospective study. INSM1 expression was detected by immunohistochemistry staining in SCLC and LCNEC tissue microarrays. The different expression of INSM1 between SCLC and LCNEC as well as the correlation with clinicopathological features including gender, age, smoking history, tumor location, AJCC 7th stage, reginal lymph node metastasis, pleural invasion and tumor thrombosis were analyzed by chi-square test. Of the included patients, male/female ratio was 2.33 (203/87) in SCLC and 10.4 (52/5) in LCNEC, the smoker rate was 64.5% (187/290) in SCLC and 43.9% (25/57) in NSCLC. According to the AJCC Cancer Staging Manual (7th edition), the SCLC patients were 29.0% (84/290) in stage I, 27.2% (79/290) in stage II, 40.7% (118/290) in stage III, and 3.1% (9/290) in stage IV, while the NSCLC patients were 49.1% (28/57) in stage I, 26.3% (15/57) in stage II, and 24.6% (14/57) in stage III, respectively. INSM1 was localized in the nucleus of lung cancer cells, a significant higher positive rate was detected in SCLC than that in LCNEC (271/290,93.4% in SCLC; 32/57,56.1% in LCNEC; p<0.05). INSM1 protein expression significantly correlated with smoking history (p=0.023), pleural invasion (p=0.010), and a positive trend of regional lymph node metastasis (p=0.052) in SCLC, but did not correlate with any of the clinicopathological features in LCNEC (p＞0.05). INSM1 protein was found no prognostic significance neither in SCLC nor in LCNEC (p＞0.05). INSM1 protein is highly expressed in SCLC and positively correlated with pleural invasion and smoking history. In contrast, INSM1 expression in LCNEC is significant lower and does not correlated with such clinicopathological features. Further research needs to be done on exploring the potential different underlying mechanisms and diagnostic significance of INSM1 in SCLC and LCNEC.

Reciprocal YAP1 loss and INSM1 expression in neuroendocrine prostate cancer.

Neuroendocrine prostate cancer (NEPC) is a rare but aggressive histologic variant of prostate cancer that responds poorly to androgen deprivation therapy. Hybrid NEPC-adenocarcinoma (AdCa) tumors are common, often eluding accurate pathologic diagnosis and requiring ancillary markers for classification. We recently performed an outlier-based meta-analysis across a number of independent gene expression microarray datasets to identify novel markers that differentiate NEPC from AdCa, including up-regulation of insulinoma-associated protein 1 (INSM1) and loss of Yes-associated protein 1 (YAP1). Here, using diverse cancer gene expression datasets, we show that Hippo pathway-related genes, including YAP1, are among the top down-regulated gene sets with expression of the neuroendocrine transcription factors, including INSM1. In prostate cancer cell lines, transgenic mouse models, and human prostate tumor cohorts, we confirm that YAP1 RNA and YAP1 protein expression are silenced in NEPC and demonstrate that the inverse correlation of INSM1 and YAP1 expression helps to distinguish AdCa from NEPC. Mechanistically, we find that YAP1 loss in NEPC may help to maintain INSM1 expression in prostate cancer cell lines and we further demonstrate that YAP1 silencing likely occurs epigenetically, via CpG hypermethylation near its transcriptional start site. Taken together, these data nominate two additional markers to distinguish NEPC from AdCa and add to data from other tumor types suggesting that Hippo signaling is tightly reciprocally regulated with neuroendocrine transcription factor expression. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

IDH2 R172 Mutations Across Poorly Differentiated Sinonasal Tract Malignancies: Forty Molecularly Homogenous and Histologically Variable Cases With Favorable Outcome.

IDH2 R172 mutations occur in sinonasal undifferentiated carcinoma (SNUC), large-cell neuroendocrine carcinoma (LCNEC), sinonasal adenocarcinomas, and olfactory neuroblastoma (ONB). We performed a clinical, pathologic, and genetic/epigenetic analysis of a large IDH2-mutated sinonasal tumor cohort to explore their distinct features. A total 165 sinonasal/skull base tumors included 40 IDH2 mutants studied by light microscopy, immunohistochemistry, and genome-wide DNA methylation, and 125 IDH2 wild-type tumors used for comparison. Methylation profiles were analyzed by unsupervised hierarchical clustering, t-distributed stochastic neighbor embedding dimensionality reduction and assessed for copy number alterations (CNA). Thirty-nine histologically assessable cases included 25 (64.1%) SNUC, 8 (20.5%) LCNEC, 2 (5.1%) poorly differentiated adenocarcinomas, 1 (2.7%) ONB, and 3 (7.7%) IDH2-mutated tumors with ONB features. All cases were high-grade showing necrosis (82.4%), prominent nucleoli (88.9%), and median 21 mitoses/10 HPFs. AE1/AE3 and/or CAM 5.2 were positive in all and insulinoma-associated protein 1 (INSM1) in 80% cases. All IDH2 mutants formed one distinct group by t-distributed stochastic neighbor embedding dimensionality reduction separating from all IDH2 wild-type tumors. There was no correlation between methylation clusters and histopathologic diagnoses. Recurrent CNA included 1q gain (79.3%), 17p loss (75.9%), and 17q gain (58.6%). No CNA differences were observed between SNUC and LCNEC. IDH2 mutants showed better disease-specific survival than SMARCB1-deficient (P=0.027) and IDH2 wild-type carcinomas overall (P=0.042). IDH2-mutated sinonasal tumors are remarkably homogeneous at the molecular level and distinct from IDH2 wild-type sinonasal malignancies. Biology of IDH2-mutated sinonasal tumors might be primarily defined by their unique molecular fingerprint rather than by their respective histopathologic diagnoses.

Expression of insulinoma-associated protein 1 in non–small cell lung cancers: a diagnostic pitfall for neuroendocrine tumors

Insulinoma-associated protein 1 (INSM1) has been reported as a highly sensitive and specific marker of neuroendocrine tumors. INSM1 expression has also been reported, although uncommonly, in non-neuroendocrine tumors. This study aimed to elucidate potential nonspecific INSM1 expression in non-small cell non-neuroendocrine lung cancers (NSCNELCs), especially in squamous cell carcinomas (SqCCs) with basaloid features to avoid diagnostic pitfalls. Tissue microarrays (TMAs) were constructed for 324 NSCNELCs, including 196 adenocarcinomas (AdCs), 86 SqCCs, and 42 other NSCNELCs. In addition, 38 whole-tissue sections of SqCCs with basaloid features were examined. INSM1 immunostain was semiquantitively evaluated based on the percentage of nuclear staining in tumor cells, categorized as negative, focal (<10% tumor cells), and positive (>10% tumor cells). Among 324 TMAs, 6.2% (20/324) were positive for INSM1, 4.9% (16/324) were focal, and 88.9% (289/34) were negative. Of 196 AdCs, 5.1% (10/196) were positive for INSM1, 4.7% (9/196) were focal, and 90.3% (177/196) were negative. Of 86 SqCCs, 9.3% (8/86) were positive for INSM1, 5.8% (5/86) were focal, and 84.9% (73/86) were negative. Of the remaining 42 NSCNELCs, 4.8% (2/42) were positive for INSM1, 4.8% (2/42) were focal, and 90.4% (38/44) were negative. Among 38 cases of whole-tissue sections of SqCCs with basaloid features, 15.8% (6/38) were positive for INSM1, 18.4% (7/38) were focal, and 65.8% (25/38) were negative. Our study demonstrates that INSM1 is expressed in a significant subset of NSCNELCs, suggesting caution in interpreting INSM1 staining, especially with limited samples. INSM1 should not be used as a stand-alone neuroendocrine marker in differentiating primary lung tumors.