Project description:Although there has been increased knowledge about the molecular biology of neuroendocrine tumors (NETs), little is known about thymic carcinoids and even less about those with excessive hormone disorders, such as ectopic ACTH syndrome. This study was designed to gain insights into molecular networks underlying the tumorigenesis of thymic carcinoids with ACTH secretion. By an approach integrating cDNA microarray and methods of computational biology, we compare gene expression profile between ACTH-producing thymic carcinoids and normal thymus. Totally there are 63 biological categories increased and 108 decreased in thymic carcinoids. Cell proliferation was stimulated which may explain the relatively uncontrolled cell growth of the tumor. Dysregulation of Notch signaling pathway was likely underlying the neuroendocrine features of this type of tumors. Moreover, the inhibition of the immunity and the increased neuropeptide signaling molecules, POMC and its sorting molecule CPE, made the clinical manifestation reasonable and thus validated the array data. In conclusion, thymic carcinoids have distinguished gene expression pattern from the normal thymus and they are characterized by deregulations of a series of biofunctions, which may be involved in the development of neuroendocrine tumor. This study hence has provided not only a detailed comprehension of the molecular pathogenesis of thymic carcinoid with ectopic ACTH syndrome, but also a road map to approach thymic neuroendocrine tumors at the system level. Transcriptome profilings were performed to identify differentially expressed cDNAs between five samples (NCs) from thymic tumor-suffering patients with ectopic ACTH syndrome (i.e., NC1, NC2, NC3, NC4, NC5, NC6) and six samples (ACs) of the noncancerous thymuses (i.e., AC1, AC2, AC3, AC4, AC5).
Project description:Although there has been increased knowledge about the molecular biology of neuroendocrine tumors (NETs), little is known about thymic carcinoids and even less about those with excessive hormone disorders, such as ectopic ACTH syndrome. This study was designed to gain insights into molecular networks underlying the tumorigenesis of thymic carcinoids with ACTH secretion. By an approach integrating cDNA microarray and methods of computational biology, we compare gene expression profile between ACTH-producing thymic carcinoids and normal thymus. Totally there are 63 biological categories increased and 108 decreased in thymic carcinoids. Cell proliferation was stimulated which may explain the relatively uncontrolled cell growth of the tumor. Dysregulation of Notch signaling pathway was likely underlying the neuroendocrine features of this type of tumors. Moreover, the inhibition of the immunity and the increased neuropeptide signaling molecules, POMC and its sorting molecule CPE, made the clinical manifestation reasonable and thus validated the array data. In conclusion, thymic carcinoids have distinguished gene expression pattern from the normal thymus and they are characterized by deregulations of a series of biofunctions, which may be involved in the development of neuroendocrine tumor. This study hence has provided not only a detailed comprehension of the molecular pathogenesis of thymic carcinoid with ectopic ACTH syndrome, but also a road map to approach thymic neuroendocrine tumors at the system level.
Project description:Pulmonary Carcinoids and Low-Grade Gastrointestinal Neuroendocrine Tumors Show Common MicroRNA Expression Profiles, Different from Adenocarcinomas and Small Cell Carcinomas
Project description:Background: It is still uncertain whether carcinoids of the lung and gastrointestinal (GI) tract have a common origin or whether they are closer in origin to carcinomas of the same organs. MicroRNA (miRNA) expression may clarify their nature and origin. Methods: First, to verify whether formalin-fixed paraffin-embedded (FFPE) samples retain the expression signature of the tissue, miRNA expression was compared between FFPE and frozen samples. Second, we selected surgically resected FFPE samples of pulmonary and GI carcinoids, as well as other types of tumors and normal tissues from each organ, and we compared the comprehensive expression patterns of miRNAs by microarray. These data were analyzed by hierarchical clustering and consensus clustering with non-negative matrix factorization (NMF). Results: The miRNA expression profiles of FFPE and frozen samples correlated quite well. In the first hierarchical clustering, most of the carcinoids formed one major cluster with loose subpartitioning into each organ type, while the second major cluster mainly comprised adenocarcinomas and normal tissues. The NMF approach largely supported hierarchical clustering. In the additional cluster analysis comparing carcinoids to small-cell lung carcinomas (SCLCs), carcinoids formed a distinct cluster, while SCLCs grouped together with pulmonary adenocarcinomas and normal lung tissues in another major cluster. Furthermore, we found some miRNAs that exhibited significant expression in carcinoids. Conclusion: Carcinoids had a characteristic pattern of miRNA expression, suggesting a common origin for pulmonary and GI carcinoids. The expression profiles were different in carcinoids and SCLCs, indicating distinct histogenesis of these neuroendocrine tumors.
Project description:The goal of this study was to characterize and classify pulmonary neuroendocrine tumors based on Array Comparative Genomic Hybridization (aCGH). Using aCGH, we performed karyotype analysis of 33 small cell lung cancer (SCLC) tumors, 13 SCLC cell lines, 19 bronchial carcinoids, and 9 gastrointestinal (GI) carcinoids. In contrast to the relatively stable karyotypes of carcinoid tumors, the karyotypes of SCLC tumors and cell lines were highly aberrant. High copy number (CN) gains were detected in SCLC tumors and cell lines in cytogenetic bands encoding JAK2, FGFR1, and MYC family members. In some of those samples, the CN of these genes exceeded 100, suggesting that they could represent driver alterations and potential drug targets in subgroups of SCLC patients. Recurrent CN alterations of a total of 203 genes, including the RB1 gene, and 59 microRNAs, most of which locate in the DLK1-DIO3 domain, were observed in SCLC tumors, bronchial carcinoids and carcinoids of GI origin; in contrast, CN alterations of the TP53 gene and the MYC family members were observed more frequently in SCLC. These findings suggest the existence of partially shared tumor-specific CN alterations in these tumors. Furthermore, we demonstrated that the aCGH profile of SCLC cell lines highly resemble that of clinical SCLC specimens. Finally, by analyzing potential drug targets, we provide a genomics based rationale for targeting the AKT-mTOR and apoptosis pathways in SCLC. Carcinoids, including 19 bronchial carcinoids and 9 carcinoid of gastrointestinal origin, and small cell lung cancer, including 33 patients' tumor samples and 13 cell line samples, were compared.
Project description:Corticotropin (ACTH)-secreting pituitary adenomas give rise to a severe endocrinological disorder, i.e., Cushing’s disease, with multifaceted clinical presentation and treatment outcomes. Experimental studies suggested that disease variability is inherent to the pituitary tumor, thus pointing to the need for further studies into tumor biology. Aim of the present study was to evaluate transcriptome expression pattern in a large series of ACTH-secreting pituitary adenoma specimens, in order to identify molecular signatures of these tumors. Gene expression profiling of formalin-fixed paraffin-embedded specimens from 40 human ACTH-secreting pituitary adenomas revealed significant expression of genes involved in protein biosynthesis and ribosomal function, in keeping with neuroendocrine cell profile. Unsupervised cluster analysis identified three distinct gene profile clusters and several genes were uniquely overexpressed in a given cluster, accounting for different molecular signatures. Of note, gene expression profiles were associated with clinical features such as age and size of the tumor. Altogether, our study shows that corticotrope tumors are characterized by neuroendocrine gene expression profile and present subgroup-specific molecular features.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.