Gene Summary

Gene:ASCL1; achaete-scute family bHLH transcription factor 1
Aliases: ASH1, HASH1, MASH1, bHLHa46
Summary:This gene encodes a member of the basic helix-loop-helix (BHLH) family of transcription factors. The protein activates transcription by binding to the E box (5'-CANNTG-3'). Dimerization with other BHLH proteins is required for efficient DNA binding. This protein plays a role in the neuronal commitment and differentiation and in the generation of olfactory and autonomic neurons. Mutations in this gene may contribute to the congenital central hypoventilation syndrome (CCHS) phenotype in rare cases. [provided by RefSeq, Jul 2008]
Databases:OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:achaete-scute homolog 1
Source:NCBIAccessed: 31 August, 2019


What does this gene/protein do?
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Cancer Overview

Research Indicators

Publications Per Year (1994-2019)
Graph generated 31 August 2019 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 31 August, 2019 using data from PubMed, MeSH and CancerIndex

Specific Cancers (5)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: ASCL1 (cancer-related)

Rudin CM, Poirier JT, Byers LA, et al.
Molecular subtypes of small cell lung cancer: a synthesis of human and mouse model data.
Nat Rev Cancer. 2019; 19(5):289-297 [PubMed] Article available free on PMC after 01/05/2020 Related Publications
Small cell lung cancer (SCLC) is an exceptionally lethal malignancy for which more effective therapies are urgently needed. Several lines of evidence, from SCLC primary human tumours, patient-derived xenografts, cancer cell lines and genetically engineered mouse models, appear to be converging on a new model of SCLC subtypes defined by differential expression of four key transcription regulators: achaete-scute homologue 1 (ASCL1; also known as ASH1), neurogenic differentiation factor 1 (NeuroD1), yes-associated protein 1 (YAP1) and POU class 2 homeobox 3 (POU2F3). In this Perspectives article, we review and synthesize these recent lines of evidence and propose a working nomenclature for SCLC subtypes defined by relative expression of these four factors. Defining the unique therapeutic vulnerabilities of these subtypes of SCLC should help to focus and accelerate therapeutic research, leading to rationally targeted approaches that may ultimately improve clinical outcomes for patients with this disease.

Rajakulendran N, Rowland KJ, Selvadurai HJ, et al.
Wnt and Notch signaling govern self-renewal and differentiation in a subset of human glioblastoma stem cells.
Genes Dev. 2019; 33(9-10):498-510 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
Developmental signal transduction pathways act diversely, with context-dependent roles across systems and disease types. Glioblastomas (GBMs), which are the poorest prognosis primary brain cancers, strongly resemble developmental systems, but these growth processes have not been exploited therapeutically, likely in part due to the extreme cellular and genetic heterogeneity observed in these tumors. The role of Wnt/βcatenin signaling in GBM stem cell (GSC) renewal and fate decisions remains controversial. Here, we report context-specific actions of Wnt/βcatenin signaling in directing cellular fate specification and renewal. A subset of primary GBM-derived stem cells requires Wnt proteins for self-renewal, and this subset specifically relies on Wnt/βcatenin signaling for enhanced tumor burden in xenograft models. In an orthotopic Wnt reporter model, Wnt

Kremer WW, van Zummeren M, Heideman DAM, et al.
HPV16-Related Cervical Cancers and Precancers Have Increased Levels of Host Cell DNA Methylation in Women Living with HIV.
Int J Mol Sci. 2018; 19(11) [PubMed] Article available free on PMC after 01/11/2019 Related Publications
Data on human papillomavirus (HPV) type-specific cervical cancer risk in women living with human immunodeficiency virus (WLHIV) are needed to understand HPV⁻HIV interaction and to inform prevention programs for this population. We assessed high-risk HPV type-specific prevalence in cervical samples from 463 WLHIV from South Africa with different underlying, histologically confirmed stages of cervical disease. Secondly, we investigated DNA hypermethylation of host cell genes

Wagner AH, Devarakonda S, Skidmore ZL, et al.
Recurrent WNT pathway alterations are frequent in relapsed small cell lung cancer.
Nat Commun. 2018; 9(1):3787 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
Nearly all patients with small cell lung cancer (SCLC) eventually relapse with chemoresistant disease. The molecular mechanisms driving chemoresistance in SCLC remain un-characterized. Here, we describe whole-exome sequencing of paired SCLC tumor samples procured at diagnosis and relapse from 12 patients, and unpaired relapse samples from 18 additional patients. Multiple somatic copy number alterations, including gains in ABCC1 and deletions in MYCL, MSH2, and MSH6, are identifiable in relapsed samples. Relapse samples also exhibit recurrent mutations and loss of heterozygosity in regulators of WNT signaling, including CHD8 and APC. Analysis of RNA-sequencing data shows enrichment for an ASCL1-low expression subtype and WNT activation in relapse samples. Activation of WNT signaling in chemosensitive human SCLC cell lines through APC knockdown induces chemoresistance. Additionally, in vitro-derived chemoresistant cell lines demonstrate increased WNT activity. Overall, our results suggest WNT signaling activation as a mechanism of chemoresistance in relapsed SCLC.

Huang YH, Klingbeil O, He XY, et al.
POU2F3 is a master regulator of a tuft cell-like variant of small cell lung cancer.
Genes Dev. 2018; 32(13-14):915-928 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
Small cell lung cancer (SCLC) is widely considered to be a tumor of pulmonary neuroendocrine cells; however, a variant form of this disease has been described that lacks neuroendocrine features. Here, we applied domain-focused CRISPR screening to human cancer cell lines to identify the transcription factor (TF) POU2F3 (POU class 2 homeobox 3; also known as SKN-1a/OCT-11) as a powerful dependency in a subset of SCLC lines. An analysis of human SCLC specimens revealed that POU2F3 is expressed exclusively in variant SCLC tumors that lack expression of neuroendocrine markers and instead express markers of a chemosensory lineage known as tuft cells. Using chromatin- and RNA-profiling experiments, we provide evidence that POU2F3 is a master regulator of tuft cell identity in a variant form of SCLC. Moreover, we show that most SCLC tumors can be classified into one of three lineages based on the expression of POU2F3, ASCL1, or NEUROD1. Our CRISPR screens exposed other unique dependencies in POU2F3-expressing SCLC lines, including the lineage TFs SOX9 and ASCL2 and the receptor tyrosine kinase IGF1R (insulin-like growth factor 1 receptor). These data reveal POU2F3 as a cell identity determinant and a dependency in a tuft cell-like variant of SCLC, which may reflect a previously unrecognized cell of origin or a

Zhang S, Li M, Ji H, Fang Z
Landscape of transcriptional deregulation in lung cancer.
BMC Genomics. 2018; 19(1):435 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
BACKGROUND: Lung cancer is a very heterogeneous disease that can be pathologically classified into different subtypes including small-cell lung carcinoma (SCLC), lung adenocarcinoma (LUAD), lung squamous cell carcinoma (LUSC) and large-cell carcinoma (LCC). Although much progress has been made towards the oncogenic mechanism of each subtype, transcriptional circuits mediating the upstream signaling pathways and downstream functional consequences remain to be systematically studied.
RESULTS: Here we trained a one-class support vector machine (OC-SVM) model to establish a general transcription factor (TF) regulatory network containing 325 TFs and 18724 target genes. We then applied this network to lung cancer subtypes and identified those deregulated TFs and downstream targets. We found that the TP63/SOX2/DMRT3 module was specific to LUSC, corresponding to squamous epithelial differentiation and/or survival. Moreover, the LEF1/MSC module was specifically activated in LUAD and likely to confer epithelial-to-mesenchymal transition, known important for cancer malignant progression and metastasis. The proneural factor, ASCL1, was specifically up-regulated in SCLC which is known to have a neuroendocrine phenotype. Also, ID2 was differentially regulated between SCLC and LUSC, with its up-regulation in SCLC linking to energy supply for fast mitosis and its down-regulation in LUSC linking to the attenuation of immune response. We further described the landscape of TF regulation among the three major subtypes of lung cancer, highlighting their functional commonalities and specificities.
CONCLUSIONS: Our approach uncovered the landscape of transcriptional deregulation in lung cancer, and provided a useful resource of TF regulatory network for future studies.

Chen C, Breslin MB, Lan MS
Sonic hedgehog signaling pathway promotes INSM1 transcription factor in neuroendocrine lung cancer.
Cell Signal. 2018; 46:83-91 [PubMed] Related Publications
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/ERK

Browne AL, Charmsaz S, Varešlija D, et al.
Network analysis of SRC-1 reveals a novel transcription factor hub which regulates endocrine resistant breast cancer.
Oncogene. 2018; 37(15):2008-2021 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
Steroid receptor coactivator 1 (SRC-1) interacts with nuclear receptors and other transcription factors (TFs) to initiate transcriptional networks and regulate downstream genes which enable the cancer cell to evade therapy and metastasise. Here we took a top-down discovery approach to map out the SRC-1 transcriptional network in endocrine resistant breast cancer. First, rapid immunoprecipitation mass spectrometry of endogenous proteins (RIME) was employed to uncover new SRC-1 TF partners. Next, RNA sequencing (RNAseq) was undertaken to investigate SRC-1 TF target genes. Molecular and patient-derived xenograft studies confirmed STAT1 as a new SRC-1 TF partner, important in the regulation of a cadre of four SRC-1 transcription targets, NFIA, SMAD2, E2F7 and ASCL1. Extended network analysis identified a downstream 79 gene network, the clinical relevance of which was investigated in RNAseq studies from matched primary and local-recurrence tumours from endocrine resistant patients. We propose that SRC-1 can partner with STAT1 independently of the estrogen receptor to initiate a transcriptional cascade and control regulation of key endocrine resistant genes.

Donakonda S, Sinha S, Dighe SN, Rao MRS
System analysis identifies distinct and common functional networks governed by transcription factor ASCL1, in glioma and small cell lung cancer.
Mol Biosyst. 2017; 13(8):1481-1494 [PubMed] Related Publications
ASCL1 is a basic Helix-Loop-Helix transcription factor (TF), which is involved in various cellular processes like neuronal development and signaling pathways. Transcriptome profiling has shown that ASCL1 overexpression plays an important role in the development of glioma and Small Cell Lung Carcinoma (SCLC), but distinct and common molecular mechanisms regulated by ASCL1 in these cancers are unknown. In order to understand how it drives the cellular functional network in these two tumors, we generated a gene expression profile in a glioma cell line (U87MG) to identify ASCL1 gene targets by an si RNA silencing approach and then compared this with a publicly available dataset of similarly silenced SCLC (NCI-H1618 cells). We constructed TF-TF and gene-gene interactions, as well as protein interaction networks of ASCL1 regulated genes in glioma and SCLC cells. Detailed network analysis uncovered various biological processes governed by ASCL1 target genes in these two tumor cell lines. We find that novel ASCL1 functions related to mitosis and signaling pathways influencing development and tumor growth are affected in both glioma and SCLC cells. In addition, we also observed ASCL1 governed functional networks that are distinct to glioma and SCLC.

Park NI, Guilhamon P, Desai K, et al.
ASCL1 Reorganizes Chromatin to Direct Neuronal Fate and Suppress Tumorigenicity of Glioblastoma Stem Cells.
Cell Stem Cell. 2017; 21(2):209-224.e7 [PubMed] Related Publications
Glioblastomas exhibit a hierarchical cellular organization, suggesting that they are driven by neoplastic stem cells that retain partial yet abnormal differentiation potential. Here, we show that a large subset of patient-derived glioblastoma stem cells (GSCs) express high levels of Achaete-scute homolog 1 (ASCL1), a proneural transcription factor involved in normal neurogenesis. ASCL1

Takagi S, Ishikawa Y, Mizutani A, et al.
LSD1 Inhibitor T-3775440 Inhibits SCLC Cell Proliferation by Disrupting LSD1 Interactions with SNAG Domain Proteins INSM1 and GFI1B.
Cancer Res. 2017; 77(17):4652-4662 [PubMed] Related Publications
T-3775440 is an irreversible inhibitor of the chromatin demethylase LSD1, which exerts antiproliferative effects by disrupting the interaction between LSD1 and GFI1B, a SNAG domain transcription factor, inducing leukemia cell transdifferentiation. Here, we describe the anticancer effects and mechanism of action of T-3775440 in small-cell lung cancer (SCLC). T-3775440 inhibited proliferation of SCLC cells

Truong N, Chun SM, Kim TI, et al.
Hypermethylation of adjacent CpG sites is negatively correlated with the expression of lineage oncogene ASCL1 in pulmonary neuroendocrine tumors.
Tumour Biol. 2017; 39(6):1010428317706225 [PubMed] Related Publications
Achaete-scute homolog 1 is a lineage oncogene of high-grade pulmonary neuroendocrine tumors. Due to the relatively few studies investigating the epigenetic regulation of achaete-scute homolog 1 expression, we wanted to address whether DNA methylation of the achaete-scute homolog 1 CpG island is associated with clinicopathological features in pulmonary neuroendocrine tumors and to investigate its effect on the expression of this gene. Here, We performed multiplex immunohistochemistry (PerkinElmer, Waltham, MA, USA) to check for achaete-scute homolog 1 and Notch homolog 1 expression in 139 pulmonary neuroendocrine tumor samples. Quantitative measurements of achaete-scute homolog 1 CpG island methylation were conducted using the MassARRAY EpiTYPER (Sequenom, San Diego, CA, USA). The correlation between immunohistochemistry data, methylation data, and clinicopathological information was analyzed. Achaete-scute homolog 1 methylation levels were increased in pulmonary neuroendocrine tumors compared to those in normal controls (0.107 vs 0.061, p < 0.001), and among the achaete-scute homolog 1 CpG island, only CpG_6 and CpG_7.8 showed higher methylation levels in pulmonary neuroendocrine tumors (0.208 and 0.135, respectively) compared to those in normal lung tissues (0.072 and 0.087, respectively; p < 0.001). Moreover, the methylation level of CpG_6.7.8 was higher in patients with stage I pulmonary neuroendocrine tumors than in patients with stage II/III pulmonary neuroendocrine tumors (0.19 ± 0.16 vs 0.14 ± 0.07, p = 0.012). The hypermethylation of CpG_6.7.8 showed an inverse correlation with achaete-scute homolog 1 protein expression (r = -0.408, p = 0.007, Spearman test). Finally, we found that CpG_6.7.8 of the achaete-scute homolog 1 CpG island is frequently hypermethylated in early-stage pulmonary neuroendocrine tumors, and this aberrant hypermethylation is negatively correlated with achaete-scute homolog 1 expression in this tumor spectrum.

Ma H, Du X, Zhang S, et al.
Achaete-scute complex homologue-1 promotes development of laryngocarcinoma via facilitating the epithelial-mesenchymal transformation.
Tumour Biol. 2017; 39(6):1010428317705752 [PubMed] Related Publications
Laryngeal cancer is one of the most common fatal cancers among head and neck carcinomas, whose mechanism, however, remains unclear. The proneural basic-helix-loop-helix protein achaete-scute complex homologue-1, a member of the basic helix-loop-helix family, plays a very important role in many cancers. This study aims to explore the clinical value and mechanism of achaete-scute complex homologue-1 in laryngeal cancer. Methods including Cell Counting Kit-8, flow cytometry, Transwell invasion assays, and scratch assay were adopted to further explore the bio-function of achaete-scute complex homologue-1, whose expression was examined in fresh and paraffin chip of laryngeal carcinoma tissues by means of western blot and immunohistochemistry, after the interference of achaete-scute complex homologue-1; achaete-scute complex homologue-1, an overexpression in laryngeal carcinoma whose carcinogenicity potential was confirmed via western blot, was correlative with T classification (p = 0.002), histological differentiation (p = 0.000), lymph node metastasis (p = 0.000), and poor survival (p = 0.000). Multivariate analysis shows that achaete-scute complex homologue-1 overexpression is an independent prognostic factor unfavorable to laryngeal carcinoma patients (p = 0.000). Moreover, knocking down achaete-scute complex homologue-1 expression could significantly suppress the proliferation, migration, and invasion of laryngeal carcinoma cell in vitro and disorder epithelial-mesenchymal transformation-associated protein expression. Achaete-scute complex homologue-1 plays an important role in the genesis and progression of laryngeal carcinoma and may act as a potential biomarker for therapeutic target and prognostic prediction.

Clarke MA, Luhn P, Gage JC, et al.
Discovery and validation of candidate host DNA methylation markers for detection of cervical precancer and cancer.
Int J Cancer. 2017; 141(4):701-710 [PubMed] Related Publications
Human papillomavirus (HPV) testing has been recently introduced as an alternative to cytology for cervical cancer screening. However, since most HPV infections clear without causing clinically relevant lesions, additional triage tests are required to identify women who are at high risk of developing cancer. We performed DNA methylation profiling on formalin-fixed, paraffin-embedded tissue specimens from women with benign HPV16 infection and histologically confirmed cervical intraepithelial neoplasia grade 3, and cancer using a bead-based microarray covering 1,500 CpG sites in over 800 genes. Methylation levels in individual CpG sites were compared using a t-test, and results were summarized by computing p-values. A total of 12 candidate genes (ADCYAP1, ASCL1, ATP10, CADM1, DCC, DBC1, HS3ST2, MOS, MYOD1, SOX1, SOX17 and TMEFF2) identified by DNA methylation profiling, plus an additional three genes identified from the literature (EPB41L3, MAL and miR-124) were chosen for validation in an independent set of 167 liquid-based cytology specimens using pyrosequencing and targeted, next-generation bisulfite sequencing. Of the 15 candidate gene markers, 10 had an area under the curve (AUC) of ≥ 0.75 for discrimination of high grade squamous intraepithelial lesions or worse (HSIL+) from

Bhinge K, Yang L, Terra S, et al.
EGFR mediates activation of RET in lung adenocarcinoma with neuroendocrine differentiation characterized by ASCL1 expression.
Oncotarget. 2017; 8(16):27155-27165 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
Achaete-scute homolog 1 (ASCL1) is a neuroendocrine transcription factor specifically expressed in 10-20% of lung adenocarcinomas (AD) with neuroendocrine (NE) differentiation (NED). ASCL1 functions as an upstream regulator of the RET oncogene in AD with high ASCL1 expression (A+AD). RET is a receptor tyrosine kinase with two main human isoforms; RET9 (short) and RET51 (long). We found that elevated expression of RET51 associated mRNA was highly predictive of poor survival in stage-1 A+AD (p=0.0057). Functional studies highlighted the role of RET in promoting invasive properties of A+AD cells. Further, A+AD cells demonstrated close to 10 fold more sensitivity to epidermal growth factor receptor (EGFR) inhibitors, including gefitinib, than AD cells with low ASCL1 expression. Treatment with EGF robustly induced phosphorylation of RET at Tyr-905 in A+AD cells with wild type EGFR. This phosphorylation was blocked by gefitinib and by siRNA-EGFR. Immunoprecipitation experiments found EGFR in a complex with RET in the presence of EGF and suggested that RET51 was the predominant RET isoform in the complex. In the microarray datasets of stage-1 and all stages of A+AD, high levels of EGFR and RET RNA were significantly associated with poor overall survival (p < 0.01 in both analyses). These results implicate EGFR as a key regulator of RET activation in A+AD and suggest that EGFR inhibitors may be therapeutic in patients with A+AD tumors even in the absence of an EGFR or RET mutation.

Allison Stewart C, Tong P, Cardnell RJ, et al.
Dynamic variations in epithelial-to-mesenchymal transition (EMT), ATM, and SLFN11 govern response to PARP inhibitors and cisplatin in small cell lung cancer.
Oncotarget. 2017; 8(17):28575-28587 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
Small cell lung cancer (SCLC) is one of the most aggressive forms of cancer, with a 5-year survival <7%. A major barrier to progress is the absence of predictive biomarkers for chemotherapy and novel targeted agents such as PARP inhibitors. Using a high-throughput, integrated proteomic, transcriptomic, and genomic analysis of SCLC patient-derived xenografts (PDXs) and profiled cell lines, we identified biomarkers of drug sensitivity and determined their prevalence in patient tumors. In contrast to breast and ovarian cancer, PARP inhibitor response was not associated with mutations in homologous recombination (HR) genes (e.g., BRCA1/2) or HRD scores. Instead, we found several proteomic markers that predicted PDX response, including high levels of SLFN11 and E-cadherin and low ATM. SLFN11 and E-cadherin were also significantly associated with in vitro sensitivity to cisplatin and topoisomerase1/2 inhibitors (all commonly used in SCLC). Treatment with cisplatin or PARP inhibitors downregulated SLFN11 and E-cadherin, possibly explaining the rapid development of therapeutic resistance in SCLC. Supporting their functional role, silencing SLFN11 reduced in vitro sensitivity and drug-induced DNA damage; whereas ATM knockdown or pharmacologic inhibition enhanced sensitivity. Notably, SCLC with mesenchymal phenotypes (i.e., loss of E-cadherin and high epithelial-to-mesenchymal transition (EMT) signature scores) displayed striking alterations in expression of miR200 family and key SCLC genes (e.g., NEUROD1, ASCL1, ALDH1A1, MYCL1). Thus, SLFN11, EMT, and ATM mediate therapeutic response in SCLC and warrant further clinical investigation as predictive biomarkers.

Duffy DJ, Krstic A, Halasz M, et al.
Retinoic acid and TGF-β signalling cooperate to overcome MYCN-induced retinoid resistance.
Genome Med. 2017; 9(1):15 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
BACKGROUND: Retinoid therapy is widely employed in clinical oncology to differentiate malignant cells into their more benign counterparts. However, certain high-risk cohorts, such as patients with MYCN-amplified neuroblastoma, are innately resistant to retinoid therapy. Therefore, we employed a precision medicine approach to globally profile the retinoid signalling response and to determine how an excess of cellular MYCN antagonises these signalling events to prevent differentiation and confer resistance.
METHODS: We applied RNA sequencing (RNA-seq) and interaction proteomics coupled with network-based systems level analysis to identify targetable vulnerabilities of MYCN-mediated retinoid resistance. We altered MYCN expression levels in a MYCN-inducible neuroblastoma cell line to facilitate or block retinoic acid (RA)-mediated neuronal differentiation. The relevance of differentially expressed genes and transcriptional regulators for neuroblastoma outcome were then confirmed using existing patient microarray datasets.
RESULTS: We determined the signalling networks through which RA mediates neuroblastoma differentiation and the inhibitory perturbations to these networks upon MYCN overexpression. We revealed opposing regulation of RA and MYCN on a number of differentiation-relevant genes, including LMO4, CYP26A1, ASCL1, RET, FZD7 and DKK1. Furthermore, we revealed a broad network of transcriptional regulators involved in regulating retinoid responsiveness, such as Neurotrophin, PI3K, Wnt and MAPK, and epigenetic signalling. Of these regulators, we functionally confirmed that MYCN-driven inhibition of transforming growth factor beta (TGF-β) signalling is a vulnerable node of the MYCN network and that multiple levels of cross-talk exist between MYCN and TGF-β. Co-targeting of the retinoic acid and TGF-β pathways, through RA and kartogenin (KGN; a TGF-β signalling activating small molecule) combination treatment, induced the loss of viability of MYCN-amplified retinoid-resistant neuroblastoma cells.
CONCLUSIONS: Our approach provides a powerful precision oncology tool for identifying the driving signalling networks for malignancies not primarily driven by somatic mutations, such as paediatric cancers. By applying global omics approaches to the signalling networks regulating neuroblastoma differentiation and stemness, we have determined the pathways involved in the MYCN-mediated retinoid resistance, with TGF-β signalling being a key regulator. These findings revealed a number of combination treatments likely to improve clinical response to retinoid therapy, including co-treatment with retinoids and KGN, which may prove valuable in the treatment of high-risk MYCN-amplified neuroblastoma.

Pantaleo MA, Urbini M, Indio V, et al.
Genome-Wide Analysis Identifies MEN1 and MAX Mutations and a Neuroendocrine-Like Molecular Heterogeneity in Quadruple WT GIST.
Mol Cancer Res. 2017; 15(5):553-562 [PubMed] Related Publications
Quadruple wild-type (WT) gastrointestinal stromal tumor (GIST) is a genomic subgroup lacking KIT/PDGFRA/RAS pathway mutations, with an intact succinate dehydrogenase (SDH) complex. The aim of this work is to perform a wide comprehensive genomic study on quadruple WT GIST to improve the characterization of these patients. We selected 14 clinical cases of quadruple WT GIST, of which nine cases showed sufficient DNA quality for whole exome sequencing (WES). NF1 alterations were identified directly by WES. Gene expression from whole transcriptome sequencing (WTS) and miRNA profiling were performed using fresh-frozen, quadruple WT GIST tissue specimens and compared with SDH and KIT/PDGFRA-mutant GIST. WES identified an average of 18 somatic mutations per sample. The most relevant somatic oncogenic mutations identified were in TP53, MEN1, MAX, FGF1R, CHD4, and CTDNN2. No somatic alterations in NF1 were identified in the analyzed cohort. A total of 247 mRNA transcripts and 66 miRNAs were differentially expressed specifically in quadruple WT GIST. Overexpression of specific molecular markers (COL22A1 and CALCRL) and genes involved in neural and neuroendocrine lineage (ASCL1, Family B GPCRs) were detected and further supported by predicted miRNA target analysis. Quadruple WT GIST show a specific genetic signature that deviates significantly from that of KIT/PDGFRA-mutant and SDH-mutant GIST. Mutations in MEN1 and MAX genes, a neural-committed phenotype and upregulation of the master neuroendocrine regulator ASCL1, support a genetic similarity with neuroendocrine tumors, with whom they also share the great variability in oncogenic driver genes.

Chou WC, Lin PH, Yeh YC, et al.
Genes involved in angiogenesis and mTOR pathways are frequently mutated in Asian patients with pancreatic neuroendocrine tumors.
Int J Biol Sci. 2016; 12(12):1523-1532 [PubMed] Article available free on PMC after 01/11/2019 Related Publications

Ito T, Kudoh S, Ichimura T, et al.
Small cell lung cancer, an epithelial to mesenchymal transition (EMT)-like cancer: significance of inactive Notch signaling and expression of achaete-scute complex homologue 1.
Hum Cell. 2017; 30(1):1-10 [PubMed] Related Publications
Small cell lung cancer (SCLC) is one of the most malignant neoplasms in common human cancers. The tumor is composed of small immature-looking cells with a round or fusiform shape, which possesses weak adhesion features among them, suggesting that SCLC shows the morphological characteristics of epithelial to mesenchymal transition (EMT). SCLC is characterized by high metastatic and recurrent rates, sensitivity to the initial chemotherapy, and easy acquirement of chemoresistance afterwards. These characters may be related to the EMT phenotype of SCLC. Notch signaling is an important signaling pathway, and could have roles in regulating neuroendocrine differentiation, proliferation, cell adhesion, EMT, and chemoresistance. Notch1 is usually absent in SCLC in vivo, but could appear after chemotherapy. Notch1 can enhance cell adhesion by induction of E-cadherin in SCLC, which indicates mesenchymal to epithelial transition. On the other hand, achaete-scute complex homologue 1 (ASCL1), negatively regulated by Notch signaling, is a lineage-specific gene of SCLC, and functions to promote neuroendocrine differentiation as well as EMT. ASCL1-transfected adenocarcinoma cell lines induced neuroendocrine phenotypes and lost epithelial cell features. SCLC is characterized by neuroendocrine differentiation and EMT-like features, which could be produced by inactive Notch signaling and ASCL1 expression. In addition, chemical and radiation treatments can activate Notch signaling, which suppress neuroendocrine differentiation and induces chemoradioresistance, accompanied by secession from EMT. Thus, the status of Notch signaling and ASCL1 expression may determine the cell behaviors of SCLC partly through modifying EMT phenotypes.

Somnay Y, Lubner S, Gill H, et al.
The PARP inhibitor ABT-888 potentiates dacarbazine-induced cell death in carcinoids.
Cancer Gene Ther. 2016; 23(10):348-354 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
Monoagent DNA-alkylating chemotherapies like dacarbazine are among a paucity of medical treatments for advanced carcinoid tumors, but are limited by host toxicity and intrinsic chemoresistance through the base excision repair (BER) pathway via poly (ADP-ribose) polymerase (PARP). Hence, inhibitors of PARP may potentiate DNA-damaging agents by blocking BER and DNA restoration. We show that the PARP inhibitor ABT-888 (Veliparib) enhances the cytotoxic effects of dacarbazine in carcinoids. Two human carcinoid cell lines (BON and H727) treated with a combination of ABT-888 and dacarbazine resulted in synergistic growth inhibition signified by combination indices <1 on the Chou-Talalay scale. ABT-888 administered prior to varying dacarbazine doses promoted the suppression of neuroendocrine biomarkers of malignancy, ASCL1 and chromogranin A, as shown by western analysis. Ataxia telangiectasia mitogen factor phosphorylation and p21

Ramalingam S, Eisenberg A, Foo WC, et al.
Treatment-related neuroendocrine prostate cancer resulting in Cushing's syndrome.
Int J Urol. 2016; 23(12):1038-1041 [PubMed] Related Publications
Here we present, to the best of our knowledge, the first case of a paraneoplastic Cushing's syndrome (hypercortisolism) resulting from treatment-related neuroendocrine prostate cancer - a highly aggressive and difficult disease to treat. A 51-year-old man was started on androgen deprivation therapy after presenting with metastatic prostate cancer, characterized by diffuse osseous metastasis. Shortly thereafter, he developed progressive disease with biopsy proven neuroendocrine prostate cancer as well as symptoms of increased skin pigmentation, hypokalemia, hypertension, hyperglycemia and profound weakness, consistent with ectopic Cushing's syndrome. Molecular analysis of the patient's tumor through RNA sequencing showed high expression of several genes including CHGA, ASCL1, CALCA, HES6, PCSK1, CALCB and INSM1 confirming his neuroendocrine phenotype; elevated POMC expression was found, supporting the diagnosis of ectopic Cushing's syndrome.

Kato F, Fiorentino FP, Alibés A, et al.
MYCL is a target of a BET bromodomain inhibitor, JQ1, on growth suppression efficacy in small cell lung cancer cells.
Oncotarget. 2016; 7(47):77378-77388 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
We aimed to elucidate the effect of JQ1, a BET inhibitor, on small cell lung cancers (SCLCs) with MYCL amplification and/or expression. Fourteen SCLC cell lines, including four with MYCL amplification, were examined for the effects of JQ1 on protein and gene expression by Western blot and mRNA microarray analyses. The sensitivity of SCLC cells to JQ1 was assessed by cell growth and apoptosis assays. MYCL was expressed in all the 14 cell lines, whereas MYC/MYCN expression was restricted mostly to cell lines with gene amplification. ASCL1, a transcription factor shown to play a role in SCLC, was also expressed in 11/14 cell lines. All SCLC cell lines were sensitive to JQ1 with GI50 values ≤1.23 μM, with six of them showing GI50 values <0.1 μM. Expression of MYCL as well as MYCN, ASCL1 and other driver oncogenes including CDK6 was reduced by JQ1 treatment, in particular in the cell lines with high expression of the respective genes; however, no association was observed between the sensitivity to JQ1 and the levels of MYCL, MYCN and ASCL1 expression. In contrast, levels of CDK6 expression and its reduction rates by JQ1 were associated with JQ1 sensitivity. Therefore, we concluded that CDK6 is a novel target of JQ1 and predictive marker for JQ1 sensitivity in SCLC cells.

Horie M, Saito A, Ohshima M, et al.
YAP and TAZ modulate cell phenotype in a subset of small cell lung cancer.
Cancer Sci. 2016; 107(12):1755-1766 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
Small cell lung cancer (SCLC) is a highly aggressive and metastatic malignancy that shows rapid development of chemoresistance and a high rate of recurrence. Recent genome and transcriptome studies have provided the whole landscape of genomic alterations and gene expression changes in SCLC. In light of the inter-individual heterogeneity of SCLC, subtyping of SCLC might be helpful for prediction of therapeutic response and prognosis. Based on the transcriptome data of SCLC cell lines, we undertook transcriptional network-defined SCLC classification and identified a unique SCLC subgroup characterized by relatively high expression of Hippo pathway regulators Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) (YAP/TAZ subgroup). The YAP/TAZ subgroup displayed adherent cell morphology, lower expression of achaete-scute complex homolog 1 (ASCL1) and neuroendocrine markers, and higher expression of laminin and integrin. YAP knockdown caused cell morphological alteration reminiscent of floating growth pattern in many SCLC cell lines, and microarray analyses revealed a subset of genes regulated by YAP, including Ajuba LIM protein (AJUBA). AJUBA also contributed to cell morphology regulation. Of clinical importance, SCLC cell lines of the YAP/TAZ subgroup showed unique patterns of drug sensitivity. Our findings shed light on a subtype of SCLC with YAP and TAZ expression, and delineate molecular networks underlying the heterogeneity of SCLC.

Zhang H, Wei M, Jiang Y, et al.
Reprogramming A375 cells to induced‑resembled neuronal cells by structured overexpression of specific transcription genes.
Mol Med Rep. 2016; 14(4):3134-44 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
Induced-resembled neuronal cells (irNCs) are generated by reprogramming human melanoma cells through the introduction of key transcription factors, providing novel concepts in the treatment of malignant tumor cells and making it possible to supply neural cells for laboratory use. In the present study, irNCs were derived from A375 cells by inducing the 'forced' overexpression of specific genes, including achaete‑scute homolog 1 (Ascl1), neuronal differentiation factor 1 (Neurod1), myelin transcription factor 1 (Myt1), brain protein 2 (Brn2, also termed POU3F2) and human brain‑derived neurotrophic factor (h‑BDNF). irNCs induced from A375 cells express multiple neuronal markers and fire action potentials, exhibiting properties similar to those of motor neurons. The reprogramming procedure comprised reverse transcription‑polymerase chain reaction and immunofluorescence staining; furthermore, electrophysiological profiling demonstrated the characteristics of the induced‑resembled neurons. The present study obtained a novel type of human irNC from human melanoma, which secreted BDNF continuously, providing a model for neuron‑like cells. Thus, irNCs offer promise in investigating various neural diseases by using neural‑like cells derived directly from the patient of interest.

Borromeo MD, Savage TK, Kollipara RK, et al.
ASCL1 and NEUROD1 Reveal Heterogeneity in Pulmonary Neuroendocrine Tumors and Regulate Distinct Genetic Programs.
Cell Rep. 2016; 16(5):1259-1272 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
Small cell lung carcinoma (SCLC) is a high-grade pulmonary neuroendocrine tumor. The transcription factors ASCL1 and NEUROD1 play crucial roles in promoting malignant behavior and survival of human SCLC cell lines. Here, we find that ASCL1 and NEUROD1 identify heterogeneity in SCLC, bind distinct genomic loci, and regulate mostly distinct genes. ASCL1, but not NEUROD1, is present in mouse pulmonary neuroendocrine cells, and only ASCL1 is required in vivo for tumor formation in mouse models of SCLC. ASCL1 targets oncogenic genes including MYCL1, RET, SOX2, and NFIB while NEUROD1 targets MYC. ASCL1 and NEUROD1 regulate different genes that commonly contribute to neuronal function. ASCL1 also regulates multiple genes in the NOTCH pathway including DLL3. Together, ASCL1 and NEUROD1 distinguish heterogeneity in SCLC with distinct genomic landscapes and distinct gene expression programs.

Polley E, Kunkel M, Evans D, et al.
Small Cell Lung Cancer Screen of Oncology Drugs, Investigational Agents, and Gene and microRNA Expression.
J Natl Cancer Inst. 2016; 108(10) [PubMed] Article available free on PMC after 01/11/2019 Related Publications
BACKGROUND: Small cell lung carcinoma (SCLC) is an aggressive, recalcitrant cancer, often metastatic at diagnosis and unresponsive to chemotherapy upon recurrence, thus it is challenging to treat.
METHODS: Sixty-three human SCLC lines and three NSCLC lines were screened for response to 103 US Food and Drug Administration-approved oncology agents and 423 investigational agents. The investigational agents library was a diverse set of small molecules that included multiple compounds targeting the same molecular entity. The compounds were screened in triplicate at nine concentrations with a 96-hour exposure time using an ATP Lite endpoint. Gene expression was assessed by exon array, and microRNA expression was derived by direct digital detection. Activity across the SCLC lines was associated with molecular characteristics using pair-wise Pearson correlations.
RESULTS: Results are presented for inhibitors of targets: BCL2, PARP1, mTOR, IGF1R, KSP/Eg5, PLK-1, AURK, and FGFR1. A relational map identified compounds with similar patterns of response. Unsupervised microRNA clustering resulted in three distinct SCLC subgroups. Associating drug response with micro-RNA expression indicated that lines most sensitive to etoposide and topotecan expressed high miR-200c-3p and low miR-140-5p and miR-9-5p. The BCL-2/BCL-XL inhibitors produced similar response patterns. Sensitivity to ABT-737 correlated with higher ASCL1 and BCL2. Several classes of compounds targeting nuclear proteins regulating mitosis produced a response pattern distinct from the etoposide response pattern.
CONCLUSIONS: Agents targeting nuclear kinases appear to be effective in SCLC lines. Confirmation of SCLC line findings in xenografts is needed. The drug and compound response, gene expression, and microRNA expression data are publicly available at

Fujino K, Motooka Y, Hassan WA, et al.
Insulinoma-Associated Protein 1 Is a Crucial Regulator of Neuroendocrine Differentiation in Lung Cancer.
Am J Pathol. 2015; 185(12):3164-77 [PubMed] Related Publications
Insulinoma-associated protein 1 (INSM1) is expressed exclusively in embryonic developing neuroendocrine (NE) tissues. INSM1 gene expression is specific for small-cell lung cancer (SCLC), along with achaete-scute homolog-like 1 (ASCL1) and several NE molecules, such as chromogranin A, synaptophysin, and neural cell adhesion molecule 1. However, the underlying biological role of INSM1 in lung cancer remains largely unknown. We first showed that surgically resected SCLC samples specifically expressed INSM1. Forced expression of the INSM1 gene in adenocarcinoma cell lines (H358 and H1975) induced the expression of ASCL1, brain-2 (BRN2), chromogranin A, synaptophysin, and neural cell adhesion molecule 1; in contrast, knockdown of the INSM1 gene by siRNA in SCLC (H69 and H889) decreased their expression. However, forced/knockdown expression of ASCL1 and BRN2 did not affect INSM1 expression. A chromatin immunoprecipitation study revealed that INSM1 bound to the promoter region of the ASCL1 gene. A xenotransplantation assay using tet-on INSM1 gene-transfected adenocarcinoma cell lines demonstrated that INSM1 induced NE differentiation and growth inhibition. Furthermore, we found that INSM1 was not expressed in non-small-cell lung cancer and some SCLC cell lines expressing Notch1-Hes1. By forced/knockdown expression of Notch1 or Hes1 genes, we revealed that Notch1-Hes1 signaling suppressed INSM1, as well as ASCL1 and BRN2. INSM1, expressed exclusively in SCLC, is a crucial regulator of NE differentiation in SCLCs, and is regulated by the Notch1-Hes1 signaling pathway.

Somnay YR, Dull BZ, Eide J, et al.
Chrysin suppresses achaete-scute complex-like 1 and alters the neuroendocrine phenotype of carcinoids.
Cancer Gene Ther. 2015; 22(10):496-505 [PubMed] Article available free on PMC after 01/11/2019 Related Publications
Carcinoids are neuroendocrine neoplasms that cause significant morbidity and mortality and for which few effective therapies are available. Given the recent identification of the anticancer flavonoid chrysin, we sought to investigate its therapeutic potential in carcinoids. Here we report chrysin's ability to modulate the achaete-scute complex-like 1 (ASCL1), a neuroendocrine-specific transcription factor highly implicated in the malignant phenotype of carcinoids and other neuroendocrine cancers. Moreover, we elucidate the role of ASCL1 in carcinoid growth and bioactivity. Treatment of two carcinoid cell lines (BON and H727) with varying chrysin concentrations suppressed cell proliferation, while reducing expression of ASCL1 and the neuroendocrine biomarker chromogranin A (CgA), demonstrated by western blotting. Propidium iodide and phycoerythrin AnnexinV/7-aminoactinomycin D staining and sorting following chrysin treatment revealed S/G2 phase arrest and apoptosis, respectively. This was corroborated by chrysin-induced cleavage of caspase-3 and poly ADP-ribose polymerase and activation of p21(Waf1/Cip1). Furthermore, direct ASCL1 knockdown with an ASCL1-specific small interfering RNA inhibited CgA and synaptophysin expression as well as carcinoid proliferation, while also reducing cyclin B1 and D1 and increasing p21(Waf1/Cip1) and p27(Kip1) expression, suggesting an arrest of the cell cycle. Collectively, these findings warrant the deliberation of targeted ASCL1 suppression by chrysin or other agents as a therapeutic approach for carcinoid management.

Lenhart R, Kirov S, Desilva H, et al.
Sensitivity of Small Cell Lung Cancer to BET Inhibition Is Mediated by Regulation of ASCL1 Gene Expression.
Mol Cancer Ther. 2015; 14(10):2167-74 [PubMed] Related Publications
The BET (bromodomain and extra-terminal) proteins bind acetylated histones and recruit protein complexes to promote transcription elongation. In hematologic cancers, BET proteins have been shown to regulate expression of MYC and other genes that are important to disease pathology. Pharmacologic inhibition of BET protein binding has been shown to inhibit tumor growth in MYC-dependent cancers, such as multiple myeloma. In this study, we demonstrate that small cell lung cancer (SCLC) cells are exquisitely sensitive to growth inhibition by the BET inhibitor JQ1. JQ1 treatment has no impact on MYC protein expression, but results in downregulation of the lineage-specific transcription factor ASCL1. SCLC cells that are sensitive to JQ1 are also sensitive to ASCL1 depletion by RNAi. Chromatin immunoprecipitation studies confirmed the binding of the BET protein BRD4 to the ASCL1 enhancer, and the ability of JQ1 to disrupt the interaction. The importance of ASCL1 as a potential driver oncogene in SCLC is further underscored by the observation that ASCL1 is overexpressed in >50% of SCLC specimens, an extent greater than that observed for other putative oncogenes (MYC, MYCN, and SOX2) previously implicated in SCLC. Our studies have provided a mechanistic basis for the sensitivity of SCLC to BET inhibition and a rationale for the clinical development of BET inhibitors in this disease with high unmet medical need.

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