Neuroendocrine prostate cancer (NEPC) is a highly aggressive and therapy-resistant subtype that arises from adenocarcinoma through lineage plasticity; however, the molecular mechanisms driving this transition remain incompletely defined. Insulinoma-associated protein 1 (INSM1), a zinc-finger transcription factor and established neuroendocrine lineage marker, has been implicated in a variety of neuroendocrine malignancies, yet its functional contribution to NEPC progression is not well understood. In this study, we demonstrate that INSM1 is consistently upregulated across NEPC patient tumors and experimental models, including both ASCL1⁺ and NEUROD1⁺ molecular subtypes, as revealed by integrated bulk and single-cell transcriptomic analyses. Functional studies revealed that INSM1 is sufficient to induce and necessary to maintain neuroendocrine lineage programs in prostate cancer, as overexpression promoted and depletion suppressed neuroendocrine-associated transcriptional networks. Mechanistically, pro-neural transcription factors, including ASCL1, NEUROD1, NEUROG3, and MYCN, directly or indirectly activate INSM1 expression, positioning it as a critical downstream effector of neuroendocrine lineage specification. Therapeutically, we identify homo-harringtonine (HHT), an FDA-approved protein synthesis inhibitor, as a potent suppressor of INSM1. HHT selectively reduces viability of INSM1-high NEPC cells at nanomolar concentrations, promotes ubiquitin-mediated degradation of INSM1, and significantly inhibits tumor growth in vivo. Notably, INSM1 depletion further enhances cellular sensitivity to HHT treatment. Collectively, our findings establish INSM1 as a key regulator of neuroendocrine plasticity and a promising therapeutic vulnerability in NEPC, providing a rationale for targeting INSM1 to suppress tumor progression.

CONTEXT:INS-VNTR class I haplotype controls INS expression in thymus that might contribute to insulin tolerance induction. OBJECTIVE:We investigate the functional activities of differential tandem repeat units (TRUs) derived from insulin autoantibody-positive and -negative patients with type 1 diabetes (T1D). METHODS:INS-VNTR class I haplotypes derived from DNA samples from 28 gender-, age-, and human leukocyte antigen (HLA)-matched patients with T1D were polymerase chain reaction amplified and subcloned into pGL3-luciferase vector. The functional activities of the INS-VNTR locus were sequenced for composition and number of TRUs, measured INS-VNTR promoter activities, and AIRE binding capacity. Small molecules that enhance INS-VNTR-luc2 activity were identified. RESULTS:The mean TRUs (average from both alleles) were significantly longer in IAA- than IAA+ patients (39.8 vs 35.2). INS-VNTR promoter activity responds to the longer TRUs better than the shorter TRUs with AIRE, suggesting that longer TRUs exhibits stronger INS expression capacity potentially favorable for tolerance induction. The binding capacity of AIRE to confer INS transcription from various INS-VNTR haplotypes was determined via ChIP and pull-down assays. The INS-VNTR probe demonstrated differential binding affinity for the AIRE protein corresponding to TRUs, suggesting a differential INS expression in thymus. AIRE protein that binds to INS-VNTR could induce endogenous INS transcript in vitro. All-trans retinoic acid (vitamin A) is capable of stimulating INS-VNTR promoter activity, which provides a valuable option of early treatment of patients with prediabetes with daily vitamin A supplement. CONCLUSION:Longer TRUs of the class I INS-VNTR haplotype favors INS expression in thymus and tolerance induction. Vitamin A supplementation could be beneficial for prevention of insulin autoimmunity at the early stages of T1D onset.

Neuroblastoma (NB), a pediatric cancer of sympatho-adrenal (SA) lineage, is marked by disrupted differentiation and cellular heterogeneity. INSM1, a zinc-finger transcription factor, is highly expressed in NB and developing SA tissues, where it regulates neuroendocrine differentiation, especially in chromaffin cells. We investigated INSM1’s role in maintaining an undifferentiated, progenitor-like state in NB and its regulation via metabolic and epigenetic mechanisms. Transcriptomic profiling, promoter assays, and metabolic flux analysis revealed that INSM1 expression correlates with methionine cycle activity, particularly the S-adenosylmethionine (SAM)/S-adenosylhomocysteine (SAH) ratio. Disruption of SAM/SAH balance altered INSM1 promoter activity and histone methylation, implicating epigenetic control in NB cell fate. Retinoic acid-induced differentiation downregulated INSM1 and N-Myc, linking INSM1 to tumor cell immaturity. INSM1 overexpression in SH-SY-5Y cells upregulated neuroendocrine and thyroid hormone-related genes (CHGA, CHGB, DDC, NCAM1, DIO3, TH), while suppressing genes involved in cell cycle (RRM, CDC25A), methionine metabolism (AHCY, MAT2A), transcriptional regulation (MYBL2, EZH2), and oncogenic signaling (ALK, LINC011667). These findings suggest that INSM1 promotes NB aggressiveness by sustaining a neuroendocrine progenitor-like phenotype through metabolic-epigenetic coupling.

High-risk neuroblastoma (NB) is a heterogeneous and malignant childhood cancer that is frequently characterized by MYCN proto-oncogene amplification or elevated N-Myc protein (N-Myc) expression. An N-Myc downstream target gene, insulinoma associated-1 (INSM1) has emerged as a biomarker that plays a critical role in facilitating NB tumor cell growth and transformation. N-Myc activates endogenous INSM1 gene expression through binding to the E2-box of the INSM1 proximal promoter in NB. We identified a plant alkaloid, homoharringtonine (HHT), from a chemical library screening showing potent inhibition of INSM1 promoter activity. This positive-hit plant alkaloid exemplifies an effective screening approach for repurposed compound targeting INSM1 expression in NB cancer therapy. The elevated N-Myc and INSM1 expression in NB constitutes a positive-loop through INSM1 activation that promotes N-Myc stability. In the present study, the biological effects and anti-tumor properties of HHT against NB were examined. HHT either down regulates and/or interferes with the binding of N-Myc to the E2-box of the INSM1 promoter and the inhibition of PI3K/AKT-mediated N-Myc stability could lead to the NB cell apoptosis. HHT inhibition of NB cell proliferation is consistent with the INSM1 expression as higher level of INSM1 exhibits a more sensitive IC50 value. The combination treatment of HHT and A674563 provides a better option of increasing potency and reducing cellular cytotoxicity than HHT or A674563 treatment alone. Taken together, the suppression of the INSM1-associated signaling pathway axis promotes the inhibition of NB tumor cell growth. This study developed a feasible approach for repurposing an effective anti-NB drug.

Human neuroblastoma (NB) is the most common childhood extracranial tumor arising from the sympathetic nervous system. It is also a clinically heterogeneous disease that ranges from spontaneous regression to high-risk stage 4 disease. The cause of this disease remains elusive. However, the amplification of NMYC oncogene occurred in roughly 30% of NB patients, which strongly correlated with the advanced stage of disease subtype and the worse prognosis status. We discovered that N-Myc oncoprotein binds and activates INSM1, a zinc-finger transcription factor of neuroendocrine tumors. We also found that INSM1 modulates N-Myc stability mediated through PI3K/AKT/GSK3β signaling pathway. Therefore, INSM1 emerges as a critical co-player with N-Myc in facilitating NB tumor cell growth and sustaining the advanced stage of malignancy. Using an INSM1-promoter driven luciferase screening-platform, we have recently identified fifteen small molecules that negatively regulate INSM1 expression. Interestingly, the identified small molecules can be divided into four large groups of compounds such as cell signaling inhibitor, DNA/RNA inhibitor, HDAC inhibitor, and cardiac glycoside. These findings support the presence of a unique mechanism associated with INSM1 and N-Myc interplay, which is critical in regulating NB tumor cell growth. We discuss the feasibility of identifying novel or repurposing small molecules targeting INSM1 as a potential treatment option for high-risk NB.

An aggressive form of neuroblastoma (NB), a malignant childhood cancer derived from granule neuron precursors and sympathoadrenal lineage, frequently comprises MYCN amplification/elevated N-Myc expression, which contributes to the development of neural crest-derived embryonal malignancy. N-Myc is an oncogenic driver in NB. Persistent N-Myc expression during the maturation of SA precursor cells can cause blockage of the apoptosis and induce abnormal proliferation, resulting in NB development. An insulinoma-associated-1 (INSM1) zinc-finger transcription factor has emerged as an NB biomarker that plays a critical role in facilitating tumor cell growth and transformation. INSM1 plays an essential role in sympathoadrenal cell differentiation. N-Myc activates endogenous INSM1 through an E2-box of the INSM1 proximal promoter, whereas INSM1 enhances N-Myc stability via RAC-α-serine/threonine protein kinase (AKT) phosphorylation in NB. The ectopic expression of INSM1 stimulates NB tumor growth in contrast to the knockdown of INSM1 that inhibits NB cell proliferation. The clinical pathological result and bioinformatics analysis show that INSM1 is a strong diagnostic and a prognostic biomarker for the evaluation of NB progression. The INSM1/N-Myc expression shows high clinical relevance in NB. Therefore, targeting the INSM1/N-Myc-associated signaling axis should be a feasible approach to identifying new drugs for the suppression of NB tumor growth.

Aggressive form of neuroblastoma (NB) is a malignant childhood cancer derived from granule neuron precursors and sympatho-adrenal lineage with N-MYC amplification. An insulinoma associated-1 (INSM1) transcription factor has emerged as a NB biomarker that plays critical role in facilitating tumor cell growth and transformation. N-myc activates INSM1 in NB was discovered. In order to elucidate the signaling pathways associated with INSM1 expression and NB tumor cell growth, we developed an INSM1 promoter-driven luciferase assay for new drug discovery. Promoter-driven luciferase assay demonstrated high Z' factor (>0.7). Performance measures using signal-to-noise ratio, signal window, and Z' factor confirmed this assay is a robust screening method. A panel of FDA-approved oncology drugs set (147 compounds) was subjected to the INSM1 promoter-driven luciferase assay. The positive-hit compounds were validated for effects on cell viability and INSM1 expression. Screening a FDA-approved oncology drugs set revealed multiple inhibitors against various signaling pathways via suppression of INSM1 promoter activity. The positive-hit compounds consist of 9 signaling pathway inhibitors negatively regulates INSM1 expression and cell viability in NB. These inhibitors target DNA/RNA/protein synthesis, tubulin assembly, and histone deacetylase signaling pathways. The outcome of this assay indicates that the newly identified pathways could be critical for NB growth and transformation. This technology and the positive-hits of multiple pathways represent a promising option of identifying re-purposed FDA-approved drugs valuable for NB treatment in the context of a NB-specific marker, INSM1.

Insulinoma-associated-1 (IA-1 or INSM1) encodes a zincfinger transcription factor, which was isolated from a human insulinoma subtraction library, with specific expression patterns, predominantly in developing neuroendocrine tissues and tumors. INSM1 is key in early pancreatic endocrine, sympatho-adrenal lineage, and pan-neurogenic precursor development. Insm1 gene ablation results in impairment of pancreatic beta cells, catecholamine biosynthesis, and basal progenitor development during mammalian neocortex maturation. Recently, INSM1 has emerged as a superior, sensitive, and specific biomarker for neuroendocrine tumors. INSM1 regulates downstream target genes and exhibits extranuclear activities associated with multiple signaling pathways, including Sonic Hedgehog, PI3K/AKT, MEK/ERK1/2, ADK, p53, Wnt, histone acetylation, LSD1, cyclin D1, Ascl1, and N-myc. Novel strategies targeting INSM1-associated signaling pathways facilitate the suppression of neuroendocrine tumor growth. In addition, INSM1 promoter-driven reporter assay and/or suicide gene therapy are promising effective therapeutic approaches for targeted specific neuroendocrine tumor therapy. In this review, the current knowledge of the biological role of INSM1 as a neuroendocrine tumor biomarker is summarized, and novel strategies targeting multiple signaling pathways in the context of INSM1 expression in neuroendocrine tumors are further explored.

Insulinoma-associated-1 (INSM1) is a key protein functioning as a transcriptional repressor in neuroendocrine differentiation and is activated by N-Myc in human neuroblastoma (NB). INSM1 modulates the phosphoinositide 3-kinase (PI3K)-AKT Ser/Thr kinase (AKT)-glycogen synthase kinase 3β (GSK3β) signaling pathway through a positive-feedback loop, resulting in N-Myc stabilization. Accordingly, INSM1 has emerged as a critical player closely associated with N-Myc in facilitating NB cell growth. Here, an INSM1 promoter-driven luciferase-based screen revealed that the compound 5′-iodotubercidin suppresses adenosine kinase (ADK), an energy pathway enzyme, and also INSM1 expression and NB tumor growth. Next, we sought to dissect how the ADK pathway contributes to NB tumor cell growth in the context of INSM1 expression. We also found that 5′-iodotubercidin inhibits INSM1 expression and induces an intra- and extracellular adenosine imbalance. The adenosine imbalance, which triggers adenosine receptor-3 signaling that decreases cAMP levels and AKT phosphorylation and enhances GSK3β activity. We further observed that GSK3β then phosphorylates β-catenin and promotes the cytoplasmic proteasomal degradation pathway. 5′-Iodotubercidin treatment and INSM1 inhibition suppressed extracellular signal-regulated kinase 1/2 (ERK1/2) activity and the AKT signaling pathways required for NB cell proliferation. The 5′-iodotubercidin treatment also suppressed β-catenin, lymphoid enhancer–binding factor 1 (LEF-1), cyclin D1, N-Myc, and INSM1 levels, ultimately leading to apoptosis via caspase-3 and p53 activation. The identification of the signaling pathways that control the proliferation of aggressive NB reported here suggests new options for combination treatments of NB patients.

Insulinoma-associated-1 (IA-1 or INSM1) encodes a zinc-finger transcription factor, which was isolated from a human insulinoma subtraction library, with specific expression patterns, predominantly in developing neuroendocrine tissues and tumors. INSM1 is key in early pancreatic endocrine, sympatho-adrenal lineage, and pan-neurogenic precursor development. Insm1 gene ablation results in impairment of pancreatic β cells, catecholamine biosynthesis, and basal progenitor development during mammalian neocortex maturation. Recently, INSM1 has emerged as a superior, sensitive, and specific biomarker for neuroendocrine tumors. INSM1 regulates downstream target genes and exhibits extranuclear activities associated with multiple signaling pathways, including Sonic Hedgehog, PI3K/AKT, MEK/ERK1/2, ADK, p53, Wnt, histone acetylation, LSD1, cyclin D1, Ascl1, and N-myc. Novel strategies targeting INSM1-associated signaling pathways facilitate the suppression of neuroendocrine tumor growth. In addition, INSM1 promoter-driven reporter assay and/or suicide gene therapy are promising effective therapeutic approaches for targeted specific neuroendocrine tumor therapy. In this review, the current knowledge of the biological role of INSM1 as a neuroendocrine tumor biomarker is summarized, and novel strategies targeting multiple signaling pathways in the context of INSM1 expression in neuroendocrine tumors are further explored. IMPLICATIONS: Neuroendocrine transcription factor (INSM1) may serve as a neuroendocrine biomarker for the development of novel cancer therapeutics against neuroendocrine tumors.

BACKGROUND:Neurogenin3 (Ngn3) and neurogenic differentiation 1 (NeuroD1), two crucial transcriptional factors involved in human diabetes (OMIM: 601724) and islet development, have been previously found to directly target to the E-boxes of the insulinoma-associated 2 (Insm2) gene promoter, thereby activating the expression of Insm2 in insulin-secretion cells. However, little is known about the function of Insm2 in pancreatic islets and glucose metabolisms.METHODS:Homozygous Insm2-/- mice were generated by using the CRISPR-Cas9 method. Glucose-stimulated insulin secretion and islet morphology were analyzed by ELISA and immunostainings. Expression levels of Insm2-associated molecules were measured using quantitative RT-PCR and Western blots.RESULTS:Fasting blood glucose levels of Insm2-/- mice were higher than wild-type counterparts. Insm2-/- mice also showed reduction in glucose tolerance and insulin/C-peptide levels when compared to the wild-type mice. RT-PCR and Western blot analysis revealed that expression of Insm1 was significantly increased in Insm2-/- mice, suggesting a compensatory response of the homolog gene Insm1. Similarly, transcriptional levels of Ngn3 and NeuroD1 were also increased in Insm2-/- mice. Moreover, Insm2-/- female mice showed a significantly decreased reproductive capacity.CONCLUSIONS:Our findings suggest that Insm2 is important in glucose-stimulated insulin secretion and is involved in the development pathway of neuroendocrine tissues which are regulated by the transcription factors Ngn3, NeuroD1 and Insm1.

Neuroendocrine (NE) lung tumors account for 20% of total lung cancer cases and represent a subset of aggressive tumors with metastatic potential. High-risk NE lung cancer patients display disseminated disease, N-myc expression/amplification, and poorly differentiated tumors. In this study, we investigate the molecular mechanisms underlying a zinc-finger transcription factor, INSM1 in NE lung cancer. Our study revealed that INSM1 crosstalk with the Shh-PI3K/AKT-N-myc/Ascl1-MEK/ERK1/2 transcriptional network in NE lung cancer. The INSM1 expression pattern and functional data demonstrated that INSM1 is not only critical for NE differentiation, but also served as a NE tumor-specific marker in small cell lung carcinoma (SCLC). The Shh signaling pathway activates INSM1 expression through N-myc and Ascl1 in aggressive SCLC. The E2-box in the INSM1 promoter is the direct target recognized by N-myc and Ascl1 transcription factors. N-myc or Ascl1 activates endogenous INSM1 expression in lung cancer cells. INSM1 functions as a key player in NE lung cancer via Shh signaling that crosstalk with PI3K/AKT and MEK/ERK1/2 pathway to enhance N-myc stability in NE lung cancer. We investigate the negative effects of Shh inhibitor and knockdown of INSM1 in NE lung cancer cells. The combination of different Shh signaling pathway inhibitors targeting INSM1 and N-myc inhibits lung cancer cell growth and could be used as a new treatment option for SCLC.

Insulinomas are the most common type of neuroendocrine (NE) pancreatic islet tumors. Patients with insulinomas may develop complications associated with hyperinsulinemia. To increase the treatment options for insulinoma patients, we have tested a conditionally replicating adenovirus that has been engineered in such a way that it can specifically express therapeutic genes in NE tumors.

INS-VNTR (insulin-variable number of tandem repeats) and AIRE (autoimmune regulator) have been associated with the modulation of insulin gene expression in thymus, which is essential to induce either insulin tolerance or the development of insulin autoimmunity and type 1 diabetes. We sought to analyze whether each functional domain of AIRE is critical for the activation of INS-VNTR in human thymic epithelial cells. Twelve missense or nonsense mutations in AIRE and two chimeric AIRE constructs were generated. A luciferase reporter assay and a pulldown assay using biotinylated INS-class I VNTR probe were performed to examine the transactivation and binding activities of WT, mutant, and chimeric AIREs on the INS-VNTR promoter. Confocal microscopy analysis was performed for WT or mutant AIRE cellular localization. We found that all of the AIRE mutations resulted in loss of transcriptional activation of INS-VNTR except mutant P252L. Using WT/mutant AIRE heterozygous forms to modulate the INS-VNTR target revealed five mutations (R257X, G228W, C311fsX376, L397fsX478, and R433fsX502) that functioned in a dominant negative fashion. The LXXLL-3 motif is identified for the first time to be essential for DNA binding to INS-VNTR, whereas the intact PHD1, PHD2, LXXLL-3, and LXXLL-4 motifs were important for successful transcriptional activation. AIRE nuclear localization in the human thymic epithelial cell line was disrupted by mutations in the homogenously staining region domain and the R257X mutation in the PHD1 domain. This study supports the notion that AIRE mutation could specifically affect human insulin gene expression in thymic epithelial cells through INS-VNTR and subsequently induce either insulin tolerance or autoimmunity.

Background: Insulinoma associated-1 (INSM1) gene is expressed exclusively in early embryonic neuroendocrine tissues, but has been found highly re-activated in most of the neuroendocrine tumors including small cell lung carcinoma.Methods: In order to elucidate the functional effects of INSM1 in normal lung development, we used a conditional lung-specific INSM1 transgenic mouse model. Transgenic (Tet-on system) CMV-INSM1 responder mice were bred with the lung-specific, club cell secretory protein (CCSP) promoter-rtTA activator mice to produce bi-transgenic progeny carrying both alleles, CCSP-rtTA and Tet-on-INSM1. Mice were fed with doxycycline containing food at the initial mating day to the postnatal day 21. Lung samples were collected at embryonic day 17.5, newborn, and postnatal day 21 for analyses.Results: Northern blot, RT-PCR, and immunohistochemical analyses revealed that doxycycline induced respiratory epithelium-specific INSM1 expression in bi-transgenic mice. Samples from postnatal day 21 mice revealed a larger lung size in the bi-transgenic mouse as compared to the single-transgenic or wild-type littermates. The histopathology results showed that the alveolar space in the bi-transgenic mice were 4 times larger than those in the single transgenic or wild-type littermates. In contrast, the size was not significantly different in the lungs collected at E17.5 or newborn among the bi-transgenic, single transgenic, or wild type mice. The respiratory epithelium with INSM1 ectopic expression suppressed cyclin D1 signal. Further in vitro studies revealed that the ectopic expression of INSM1 suppresses cyclin D1 expression and delays cell cycle progression.Conclusion: The current study suggests that CCSP promoter-driven INSM1 ectopic expression impairs normal lung development especially in postnatal alveologenesis.

Following the publication of this article, an interested reader drew to our attention an anomaly associated with the presentation of Figs. 5 and 8; essentially, the β-actin control bands in Fig. 8 appeared to be a mirror image of the same control bands shown in Fig. 5A. After having re‑examined the data, Fig. 5 was correctly presented as shown in the paper, although the β-actin blot in Fig. 8 had been inadvertently misplaced as a mirror image of the control data from Fig. 5. Two similar experiments were performed at that time, yielding similar results, and the error with the control data did not affect the second of the experiments. Therefore, we present a corrected version of Fig. 8 containing the alternative data. The findings and conclusions of this paper are still supported by our experimental data, and were not affected by this error. We sincerely apologize for this mistake, and thank the reader of our article who drew this matter to our attention. Furthermore, we regret any inconvenience this mistake has caused. [the original article was published in the International Journal of Oncology 42: 1113-1119, 2013; DOI: 10.3892/ijo.2013.1789].

Insulinoma associated-1 (IA-1/INSM1) gene is exclusively expressed during early embryonic development, but has been found to be re-expressed at high levels in neuroendocrine tumors including neuroblastoma. Using over-expression and knockdown experiments in neuroblastoma cells, we showed that INSM1 is critical for cell proliferation, BME-coated invasion, and soft agar colony formation. Here, we identified INSM1 as a novel target gene activated by N-myc in N-myc amplified neuroblastoma cells. The Sonic hedgehog signaling pathway induced INSM1 by increasing N-myc expression. INSM1 activated PI3K/AKT/GSK3β pathways to suppress N-myc phosphorylation (Thr-58) and inhibited degradation of N-myc. Inversely, N-myc protein bound to the E2-box region of the INSM1 promoter and activated INSM1 expression. The invasion assay and the xenograft nude mouse tumor model revealed that the INSM1 factor facilitated growth and oncogenesis of neuroblastoma. The current data supports our hypothesis that a positive-feedback loop of sonic hedgehog signaling induced INSM1 through N-myc and INSM1 enhanced N-myc stability contributing to the transformation of human neuroblastoma.

Accurate detection of neuroendocrine (NE) tumors is critically important for better prognosis and treatment outcomes in patients. To demonstrate the efficacy of using an adenoviral vector for the detection of NE tumors, we have constructed a pair of adenoviral vectors which, in combination, can conditionally replicate and release Gaussia luciferase into the circulation after infecting the NE tumors. The expression of these two vectors is regulated upstream by an INSM1-promoter (insulinoma-associated-1) that is specifically active in NE tumors and developing NE tissues, but silenced in normal adult tissues. In order to retain the tumor-specificity of the INSM1 promoter, we have modified the promoter using the core insulator sequence from the chicken β-globin HS4 insulator and the neuronal restrictive silencing element (NRSE). This modified INSM1-promoter can retain NE tumor specificity in an adenoviral construct while driving a mutated adenovirus E1A gene (∆24E1A), the Metridia, or Gaussia luciferase gene. The in vitro cell line and mouse xenograft human tumor studies revealed the NE specificity of the INSM1-promoter in NE lung cancer, neuroblastoma, medulloblastoma, retinoblastoma, and insulinoma. When we combined the INSM1-promoter driven Gaussia luciferase with ∆24E1A, the co-infected NE tumor secreted higher levels of Gaussia luciferase as compared to the INSM1p-Gaussia virus alone. In a mouse subcutaneous xenograft tumor model, the combination viruses secreted detectable level of Gaussia luciferase after infecting an INSM1-positive NE lung tumor for ≥12 days. Therefore, the INSM1-promoter specific conditional replicating adenovirus represents a sensitive diagnostic tool to aid clinicians in the detection of NE tumors.