Insulinoma-associated protein 1 (INSM1): a potential biomarker and therapeutic target for neuroendocrine tumors

A comparative study of INSM1 (clone MRQ70) immunoreactivity on CytoLyt® pretreated cytology and resection specimens of pancreatic neuroendocrine tumors

INTRODUCTION

Insulinoma-associated protein 1 (INSM1) is a newly characterized sensitive and specific immunohistochemical marker for neuroendocrine (NE) tumors. Whereas more traditional NE markers, such as chromogranin A and synaptophysin, are cytoplasmic, INSM1 is uniquely nuclear and thus could serve as a useful addition to NE tumor workup. While application of immunohistochemical studies to cytology specimens is becoming increasingly relevant, knowledge of the effects of the certain fixatives as well as the pattern and intensity of immunoexpression are important considerations.

METHODS

Sixteen cases of pancreatic neuroendocrine tumor (PanNET) diagnosed between 2015 and 2021 underwent both fine-needle aspiration, which was subsequently prepared in CytoLyt®-fixed cytology cell block (CCB), and surgical resection, in which specimens were prepared into formalin-fixed paraffin embedded blocks (FFPE). For all samples, INSM1 immunoreactivity was classified according to staining intensity and extent, then compared between CCBs and matched FFPEs.

RESULTS

All 16 FFPE specimens demonstrated strong and diffuse INSM1 immunoreactivity, while only 10/16 (62.5%) CCBs were positive. Of those 10, only 2/10 (20%) demonstrated strong and diffuse reactivity.

CONCLUSION

The choice of fixative has a demonstrable effect on the immunoreactivity of INSM1 in PanNET. Even though the sensitivity is lower in CytoLyt®-fixed cell block specimens, the addition of INSM1 is useful, especially in challenging cases that may be negative for one or more of the traditional NE markers.

Molecular classification of small cell lung cancer subtypes: Characteristics, prognostic factors, and clinical translation

ABSTRACT

Small cell lung cancer (SCLC) is a highly malignant tumor with a very poor prognosis; therefore, more effective treatments are urgently needed for patients afflicted with the disease. In recent years, emerging molecular classifications based on key transcription factors of SCLC have provided more information on the tumor pathophysiology, metastasis, immune microenvironment, and acquired therapeutic resistance and reflected the intertumoral heterogeneity of the various SCLC phenotypes. Additionally, advances in genomics and single-cell sequencing analysis have further revealed the high intratumoral heterogeneity and plasticity of the disease. Herein, we review and summarize these recent lines of evidence and discuss the possible pathogenesis of SCLC.

The Significance of Insulinoma-Associated Protein 1 in the Pathological Diagnosis of Small-Cell Lung Cancer in Biopsy Specimens

Objective: Our purpose was to investigate the clinicopathological diagnostic value of immunohistochemical antibody for insulinoma-associated protein 1 (INSM1) in biopsy specimens of SCLC. Methods: Biopsy specimens of SCLC diagnosed at the pathology department of Tangshan Gongren Hospital from January 2022 to June 2023 were selected. INSM1 expression was detected and compared with conventional neuroendocrine markers synaptophysin (SYP), chromogranin A (CHGA), and CD56 regarding expression sensitivity and specificity. Results: The sensitivity of INSM1 expression was significantly higher than that of CHGA (95% vs 50%, P = .000), but there was no statistically significant difference in the specificity of INSM1, SYP, CHGA, and CD56 expression (100% vs 94% vs 98% vs 92%, respectively, P = .241, 1.000, .126). Conclusions: INSM1 antibody shows high sensitivity and specificity in the expression of SCLC and serves as a reliable immunohistochemical marker in the clinicopathological diagnosis of SCLC in biopsy specimens.

The role of insulinoma-associated protein 1 in predicting the progression and prognosis of human olfactory neuroblastoma in China

OBJECTIVE

Recent studies have suggested that insulinoma-associated protein 1 (INSM1) is a useful marker for pathological diagnosis of neuroendocrine tumors. In the present study, we investigated the association between INSM1 expression and prognosis in patients with olfactory neuroblastoma (ONB) and assessed the usefulness of INSM1 as a prognostic biomarker in these patients.

METHOD

Immunohistochemistry was performed on 109 ONB patients who underwent endoscopic surgery at Beijing Tong Ren Hospital (Beijing, China) between June 2006 and November 2021 Patient age at the time of surgery ranged from 10 months to 72 years (mean age, 43.55 ± 13.47 years). In total, 63 (57.8%) and 46 (42.2%) tumors occurred in male and female patients, respectively. The percentages of grade I-IV cases were 13.8% (15/109), 36.7% (40/109), 29.4% (32/109) and 20.2% (22/109), respectively.

RESULTS

The expression rate (moderately/strongly positive) of INSM1 was significantly higher in high-grade (Ⅲ/Ⅳ; 83%; 45/54) than low-grade (Ⅰ/Ⅱ; 27%; 15/55) ONB cases. High expression levels of INSM1 were significantly positively associated with high pathological stage (p < 0.001), local recurrence, and death. Kaplan‑Meier analysis revealed that patients with high INSM1 expression had significantly shorter disease‑free survival (DFS) and mean survival (75.01 ± 10.71 vs. 158.56 ± 10.32) times, and shorter overall survival (OS). Multivariate Cox regression analysis revealed that INSM1 was an independent prognostic factor for DFS (HR: 4.963, 95%CI [2.11-10.84] p < 0.001) and OS (HR: 4.791, 95%CI [2.117-10.485], p < 0.001) after adjusting for sex, age, and tumor grade. In addition, INSM1 was an independent prognostic factor for DFS in patients treated with surgery (HR: 3.714, 95%CI [1.267-10.889], p = 0.017) and chemotherapy (HR: 5.574, 95%CI [1.584-19.612], p = 0.007).

CONCLUSION

INSM1 expression had a positive association with the prognosis of patients with ONB and could serve as a prognostic biomarker in these patients.

Osamura R, Shiomi T, Matsuno A. Analysis of Insulinoma-Associated Protein 1 Expression in Pituitary Neuroendocrine Tumors

Insulinoma-associated protein 1 (INSM1) is a representative diagnostic marker of neuroendocrine neoplasms (NENs); however, it has not yet been used to diagnose pituitary neuroendocrine tumors (PitNETs), according to the 2022 World Health Organization (WHO) classification of pituitary tumors. This study aimed to examine the expression of INSM1 using immunohistochemistry, in the various cell lineages of PitNET classified by hormone secretion and transcription factor expression. INSM1 expression in PitNETs (different subtypes) and normal pituitary tissues was immunohistochemically assessed. The results were interpreted as scores of 0 (negative), 1 (focally positive), or 2 (frankly positive), depending on the proportion of cell staining. Twenty-eight of 35 PitNET cases (80%) showed INSM1 positivity in their nuclei. The staining in each histological subtype of PitNETs was as follows: somatotroph tumors, score 0 = 3/5, score 1 = 1/5, score 2 = 1/5; lactotroph tumors, score 0 = 2/5, score 1 = 1/5, score 2 = 2/5; thyrotroph tumors, score 2 = 5/5; corticotroph tumors: score 1 = 1/9, score 2 = 8/9; gonadotroph tumors, score 0 = 2/10, score 1 = 0/10, score 2 = 8/10; and unclassifiable tumor, score 1 = 1/1. INSM1 expression in most PitNETs was obtained, similar to that in the normal pituitary gland; thus, INSM1 may maintain the characteristics of anterior pituitary cells and pituitary tumors.

[Whipple's triad with high and low insulin levels]

A 69-year-old female patient and a 70-year-old male patient were admitted to hospital with recurrent, severe hypoglycemic episodes and a typical manifestation of Whipple's triad. In the female, elevated levels of insulin, C‑peptide and pro-insulin together with pathological findings during a fasting test proved the presence of an insulinoma, which could be detected by Ga-68-DOTATOC-PET-CT in the pancreas. There was a very rare co-existence of a neuroendocrine Merkel cell carcinoma. In the male, levels of insulin and C‑peptide were suppressed and a diagnosis of paraneoplastic hypoglycemia by IGF‑2 secretion was made with increased glucose disposal in skeletal muscle proven by ¹⁸F‑FDG-PET-CT.

INSM1 Expression in Mesenchymal Tumors and Its Clinicopathological Significance

BACKGROUND

Insulinoma-associated protein 1 (INSM1) has been identified as a nuclear marker of neuroendocrine tumors. Although INSM1 appears to be a subtle and specific biomarker for neuroendocrine tumor, its expression and clinicopathological significance in mesenchymal tumors remain unclear.

METHODS

We analyzed INSM1 mRNA level in GEO database and conducted immunohistological staining to detect the expression of INSM1 on 576 mesenchymal tumors from pathology department of Tongji Hospital.

RESULTS

At transcription level, INSM1 expression in AITL (angioimmunoblastic T-cell lymphoma) was higher than their adjacent normal tissues as well as Hodgkin's lymphoma. Moreover, INSM1 expression in well-differentiated liposarcoma (WDLPS) was significantly higher than normal fat (P = 0.014) and dedifferentiated liposarcoma (DDLPS) (P = 0.0248). At protein level, the positive rate of INSM1 in AITL was 18/48 (47.4%), while in DDLPS was 9/20 (45%). INSM1 expression in AITL was significantly higher than Hodgkin's lymphoma (P = 0.008). And INSM1 expression in WDLPS was significantly lower than DDLPS (P = 0.015).

CONCLUSION

The combination of GEO data and immunohistochemistry data indicated that the expression level of INSM1 was higher in AITL compared with normal control, suggesting that INSM1 may be involved in pathogenesis of AITL. The abnormal expression of INSM1 was found in WDLPS, and the positive rate of INSM1 was higher in DDLPS than in WDLPS. INSM1 may be involved in the regulation of liposarcoma development. There were significant differences in the expression of INSM1 between AITL and Hodgkin's lymphoma and WDLPS and DDLPS. These findings may assist in the differential diagnosis of these tumors when common markers are difficult to identify, enriching the diagnostic index system of mesenchymal tumors.

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.

Comprehensive in Vitro Characterization of the LSD1 Small Molecule Inhibitor Class in Oncology

Lysine-specific demethylase 1 (LSD1 or KDM1A) is a chromatin modifying enzyme playing a key role in the cell cycle and cell differentiation and proliferation through the demethylation of histones and nonhistone substrates. In addition to its enzymatic activity, LSD1 plays a fundamental scaffolding role as part of transcription silencing complexes such as rest co-repressor (CoREST) and nucleosome remodeling and deacetylase (NuRD). A host of classical amine oxidase inhibitors such as tranylcypromine, pargyline, and phenelzine together with LSD1 tool compounds such as SP-2509 and GSK-LSD1 have been extensively utilized in LSD1 mechanistic cancer studies. Additionally, several optimized new chemical entities have reached clinical trials in oncology such as ORY-1001 (iadademstat), GSK2879552, SP-2577 (seclidemstat), IMG-7289 (bomedemstat), INCB059872, and CC-90011 (pulrodemstat). Despite this, no single study exists that characterizes them all under the same experimental conditions, preventing a clear interpretation of published results. Herein, we characterize the whole LSD1 small molecule compound class as inhibitors of LSD1 catalytic activity, disruptors of SNAIL/GFI1 (SNAG)-scaffolding protein-protein interactions, inducers of cell differentiation, and potential anticancer treatments for hematological and solid tumors to yield an updated, unified perspective of this field. Our results highlight significant differences in potency and selectivity among the clinical compounds with iadademstat being the most potent and reveal that most of the tool compounds have very low activity and selectivity, suggesting some conclusions derived from their use should be taken with caution.

INSM1 Expression in Breast Neoplasms with Neuroedocrine Features

According to the 2019 WHO classification of breast tumors, neuroendocrine neoplasms (NENs) are classified into well-differentiated NE tumors (NET) and poorly differentiated NE carcinomas (NEC), while other breast cancers (BCs) of special and no special type with neuroendocrine (NE) features are not incorporated in this scheme anymore. We aimed to assess whether INSM1, a novel NE marker, could have a role in breast NEN subtyping. We selected 63 BCs operated from 2003 to 2018, classified as BCs with NE features, with available clinico-pathological data. Following 2019 WHO criteria, this cohort was reclassified into 37 NETs/NECs, the remaining 26 tumors representing solid-papillary (7), mucinous (7), and mixed type (12) carcinomas with NE differentiation. Chromogranin A (CGA) and synaptophysin (SYN) immunostains were reviewed, and INSM1 was tested by immunohistochemistry. Thirty CGA- and SYN-negative no special type BCs served as negative control. INSM1 was expressed in 52/63 cases of the whole cohort (82.54%). INSM1 positive and negative cases had no significantly different clinico-pathological characteristics. INSM1 expression was not significantly different between the newly reclassified NET/NEC group and other BCs with NE features. No immunoexpression was observed in control BCs. The sensitivity and specificity of INSM1 for the NE phenotype was 82.5% and 100%, respectively, compared to 61.9% and 100% for CGA, and 95.2 and 100% for SYN. In conclusion, INSM1 is as accurate as traditional NE biomarkers to identify NE differentiation in BC. In analogy to standard NE markers, INSM1 could not distinguish NET and NEC from the other BC histotypes with NE differentiation.

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

BACKGROUND

Small 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.

METHODS

We 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.

RESULTS

High 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.

CONCLUSION

Our 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.

MI-773, a breaker of the MDM2/p53 axis, exhibits anticancer effects in neuroblastoma via downregulation of INSM1

Neuroblastoma (NB) is a common pediatric malignancy associated with poor outcomes. Recent studies have shown that murine double minute2 homolog (MDM2) protein inhibitors are promising anticancer agents. MI-773 is a novel and specific antagonist of MDM2, however, the molecular mechanism of its anti-NB activity remains unclear. NB cell viability was measured by Cell Counting Kit-8 assay following MI-773 treatment. Cell cycle progression was analyzed using PI staining and apoptosis was assessed using Annexin V/PI staining. The molecular mechanisms by which MI-773 exerted its effects were investigated using a microarray. The results showed that disturbance of the MDM2/p53 axis by MI-773 resulted in potent suppression of proliferation, induction of apoptosis and cell cycle arrest in NB cells. In addition, microarray analysis showed that MI-773 led to significant downregulation of genes involved in the G₂/M phase checkpoint and upregulation of hallmark gene associated with the p53 pathway. Meanwhile, knockdown of insulinoma-associated 1 decreased proliferation and increased apoptosis of NB cells. In conclusion, the present study demonstrated that MI-773 exhibited high selectivity and blockade affinity for the interaction between MDM2 and TP53 and may serve as a novel strategy for the treatment of NB.

Insulinoma-associated protein 1(INSM1) is a superior marker for the diagnosis of gastroenteropancreatic neuroendoerine neoplasms: a meta-analysis

PURPOSE

An increasing number of studies have shown that insulinoma-associated protein 1 (INSM1) is a robust marker for the diagnosis of gastroenteropancreatic neuroendocrine neoplasms (GEP-NEN). The overall diagnostic accuracy of INSM1 for GEP-NEN remains unclear. The purpose of this study is to estimate the diagnostic value of INSM1 for GEP-NEN through a meta-analysis.

METHODS

We searched relevant studies addressing the accuracy of INSM1 in the diagnosis of GEP-NEN from PubMed, Web of Science, Embase, Cochrane Library and China National Knowledge Infrastructure (CNKI) as well as from reference lists since the establishment of the database to January 12, 2021. Pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and summary receiver operating characteristic (SROC) curves were used to comprehensively evaluate the diagnostic value of INSM1 for GEP-NEN. Statistical analysis was performed by Stata 15.0 and RevMan 5.4.

RESULTS

Nine studies with a total of 393 patients were included in the meta-analysis. The meta-analysis results showed that the pooled sensitivity and specificity of INSM1 for the diagnosis of GEP-NEN were 0.99 (95% CI: 0.87-1.00) and 0.96 (95% CI: 0.93-0.98), respectively. The PLR and NLR were 23.3 (95% CI: 13.3-40.8) and 0.01 (95% CI: 0.00-0.14), respectively. The DOR was 380.31 (95% CI: 164.14-881.21), and the area under the curve (AUC) of SROC curve was 0.98 (95% CI: 0.96-0.99).

CONCLUSIONS

The results show that INSM1 is an effective marker for the diagnosis of GEP-NEN with high sensitivity and specificity. INSM1 is recommended for clinical application to improve the diagnostic accuracy of GEP-NEN. However, more high-quality studies are needed to confirm these findings.

Utility of Insulinoma-Associated Protein 1 (INSM1) and Mucin 2 (MUC2) Immunohistochemistry in the Distinction of Endocrine Mucin-Producing Sweat Gland Carcinoma From Morphologic Mimics

ABSTRACT

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare low-grade adnexal malignancy with a predilection for the eyelids of elderly White women, which is associated with invasive mucinous carcinoma with endocrine features in one-third of cases. EMPSGC is characterized by the presence of neuroendocrine differentiation and mucin production. However, EMPSGC displays a variety of architectural patterns including solid, cribriform, papillary, and cystic growth. In addition, EMPSGC may also display nonendocrine cytologic features, such as apocrine change. Because of their variable appearance, EMPSGC can show significant morphologic overlap with certain histologic mimics, namely basal cell carcinoma, hidrocystoma, apocrine hidradenoma, and tubular adenoma. In addition, the often limited sampling of this anatomically delicate area can make the diagnosis of EMPSGC challenging. EMPSGC expresses neuroendocrine markers, including synaptophysin and chromogranin, often in a focal distribution. However, insulinoma-associated protein 1 (INSM1) has been found to be a more sensitive marker for EMPSGC. Recent studies have also demonstrated the expression of the gel-forming mucin 2 (MUC2) in EMPSGC, possibly signifying a lacrimal or conjunctival origin of these neoplasms. In this article, we discuss EMPSGC in the context of its histologic mimics (BCC, hidrocystoma, apocrine hidradenoma, and tubular adenoma) and we investigate the utility of the immunohistochemical expression of INSM1 and MUC2 in the distinction of EMPSGC from them. We demonstrate that INSM1 and MUC2 can reliably distinguish EMPSGC from these histologic mimics.

Application of INSM1 in Diagnosis and Grading of Laryngeal Neuroendocrine Carcinoma

OBJECTIVE

Chromogranin (CHG), synaptophysin (Syn), and CD56 are generally used in a panel to support diagnoses of laryngeal neuroendocrine carcinomas (NECs). However, the absence of expression of these markers does not completely exclude the diagnosis. INSM1 is a novel marker that is considered sufficiently sensitive and specific for NE differentiation. The aim of this study is not only to detect its sensitivity and specificity, but also to evaluate its application in grading for laryngeal NECs.

METHODS

The clinicopathological characteristics of the 25 cases with laryngeal NECs were retrospectively analyzed. The expressions of INSM1, CHG, Syn, and CD56 were detected by immunohistochemistry.

RESULTS

Of the 25 laryngeal NECs, INSM1 had higher sensitivity (92%) than Syn (84%), CHG (76%) and CD56 (76%). The average H scores of INSM1, CD56, Syn, and CHG were 160, 37.5, 300, 300 for well-differentiated neuroendocrine carcinoma (WD-NEC); 190, 149, 209, 215 for moderately differentiated neuroendocrine carcinoma (MD-NEC); 251, 208, 104, 25 for poorly differentiated neuroendocrine carcinoma with small cell (SCNEC); 109, 160, 98, 26 for large cell types (LCNEC), respectively. Of these 98 non-neuroendocrine tumors, INSM1 expression was seen in nine (9%) tumors, all were squamous cell carcinoma. And INSM1 staining was generally focal.

CONCLUSION

INSM1 has high sensitivity and specificity in diagnosis of laryngeal NECs. For grading laryngeal NECs, Syn and CHG showed significant advantages in the diagnosis of WD-NEC and MD-NEC, whereas INSM1 and CD56 showed greater diagnostic value in the diagnosis of SCNEC and LCNEC, especially in SCNEC.

LEVEL OF EVIDENCE

4 Laryngoscope, 2021.

Next Generation Sequencing analysis suggests varied multistep mutational pathogenesis for Endocrine Mucin Producing Sweat Gland Carcinoma with comments on INSM1 and MUC2 suggesting a conjunctival origin

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a low-grade eyelid tumor. Small biopsies and insensitive immunohistochemistry predispose to misdiagnosis. We aimed to identify clarifying immunohistochemical and/or molecular markers. Clinicopathologic data (22 cases) was reviewed. Immunohistochemistry (Insulinoma-associated protein-1(INSM1), BCL-2, MUC2, MUC4, androgen-receptor, Beta-catenin, MCPyV) and next generation sequencing (MSK-IMPACT, 468 genes) was performed (3 cases). Female (n=15) and male (n=7) patients, mean-age 71.8 years (53-88), had eyelid/periorbital tumors (>90%) with mucin-containing solid/cystic neuroendocrine pathology. Immunohistochemistry (INSM1, BCL2, androgen-receptor, RB1, Beta-catenin) was diffusely-positive (5/5), MUC2 partial, MUC4 focal, and MCPyV negative. MSK-IMPACT identified 12 single-nucleotide-variants and one in-frame deletion in 3 cases, each with DNA damage response/repair (BRD4, PPP4R2, RTEL1) and tumor-suppressor pathway (BRD4, TP53, TSC1, LATS2) mutations. Microsatellite instability, copy number alterations, and structural alterations were absent. INSM1 and MUC2 are positive in EMPSGC. MUC2 positivity suggests conjunctival origin. Multistep pathogenesis involving DNA damage repair and tumor-suppressor pathways may be implicated.

Transcriptomic analysis identifies a tumor subtype mRNA classifier for invasive non-functioning pituitary neuroendocrine tumor diagnostics

Rationale: The invasive behavior of non-functioning pituitary neuroendocrine tumors (NF-PitNEts) presents obstacles for complete surgical resection and is indicative of poor prognosis. Therefore, developing reliable diagnostic tools for identifying invasive PitNEts would be helpful in guiding surgical decisions and, in particular, the follow-up treatment.

Methods: We analyzed differential gene expression profiles between 39 non-invasive and 22 invasive NF-PitNEts by high-throughput sequencing, gene co-expression, and functional annotation. Twenty-one transcripts were further validated by Taqman-qPCR in another 143 NF-PitNEt samples. The histological expression and serum-exosomal mRNA of three candidate genes were examined by tissue microarray and droplet digital PCR.

Results: Non-invasive and invasive NF-PitNEts were clustered into distinct groups with a few outliers because of their gonadotroph, corticotroph, or null cell lineages. The gene signature with strong invasive potential was enriched in 'Pathways in cancers' and 'MAPK pathway', with significantly higher in situ INSM1 and HSPA2 protein expression in invasive NF-PitNEts. Further integration of the 20 qPCR-validated differentially expressed genes and pituitary cell lineages provided a gene-subtype panel that performed 80.00-90.24% diagnostic accuracy for the invasiveness of NF-PitNEts.

Conclusion: Our approach defined new characteristics in the core molecular network for patients at risk for invasive NF-PitNEt, representing a significant clinical advance in invasive PitNEt diagnostics.