Next-generation sequencing identifies novel mitochondrial variants in pituitary adenomas.

PURPOSE: Disrupted mitochondrial functions and genetic variants of mitochondrial DNA (mtDNA) have been observed in different human neoplasms. Next-generation sequencing (NGS) can be used to detect even low heteroplasmy-level mtDNA variants. We aimed to investigate the mitochondrial genome in pituitary adenomas by NGS. METHODS: We analysed 11 growth hormone producing and 33 non-functioning [22 gonadotroph and 11 hormone immunonegative] pituitary adenomas using VariantPro™ Mitochondrion Panel on Illumina MiSeq instrument. Revised Cambridge Reference Sequence (rCRS) of the mtDNA was used as reference. Heteroplasmy was determined using a 3% cutoff. RESULTS: 496 variants were identified in pituitary adenomas with overall low level of heteroplasmy (7.22%). On average, 35 variants were detected per sample. Samples harbouring the highest number of variants had the highest Ki-67 indices independently of histological subtypes. We identified eight variants (A11251G, T4216C, T16126C, C15452A, T14798C, A188G, G185A, and T16093C) with different prevalences among different histological groups. T16189C was found in 40% of non-recurrent adenomas, while it was not present in the recurrent ones. T14798C and T4216C were confirmed by Sanger sequencing in all 44 samples. 100% concordance was found between NGS and Sanger method. CONCLUSIONS: NGS is a reliable method for investigating mitochondrial genome and heteroplasmy in pituitary adenomas. Out of the 496 detected variants, 414 have not been previously reported in pituitary adenoma. The high number of mtDNA variants may contribute to adenoma genesis, and some variants (i.e., T16189C) might associate with benign behaviour.

Limitations of high throughput methods for miRNA expression profiles in non-functioning pituitary adenomas.

Microarray, RT-qPCR based arrays and next-generation-sequencing (NGS) are available high-throughput methods for miRNA profiling (miRNome). Analytical and biological performance of these methods were tested in identification of biologically relevant miRNAs in non-functioning pituitary adenomas (NFPA). miRNome of 4 normal pituitary (NP) and 8 NFPA samples was determined by these platforms and expression of 21 individual miRNAs was measured on 30 (20 NFPA and 10 NP) independent samples. Complex bioinformatics was used. 132 and 137 miRNAs were detected by all three platforms in NP and NFPA, respectively, of which 25 were differentially expressed (fold change > 2). The strongest correlation was observed between microarray and TaqMan-array, while the data obtained by NGS were the most discordant despite of various bioinformatics settings. As a technical validation we measured the expression of 21 selected miRNAs by individual RT-qPCR and we were able to validate 35.1%, 76.2% and 71.4% of the miRNAs revealed by SOLiD, TLDA and microarray result, respectively. We performed biological validation using an extended number of samples (20 NFPAs and 8 NPs). Technical and biological validation showed high correlation (p < 0.001; R = 0.96). Pathway and network analysis revealed several common pathways but no pathway showed the same activation score. Using the 25 platform-independent miRNAs developmental pathways were the top functional categories relevant for NFPA genesis. The difference among high-throughput platforms is of great importance and selection of screening method can influence experimental results. Validation by another platform is essential in order to avoid or to minimalize the platform specific errors.

MEN1 and microRNAs: The link between sporadic pituitary, parathyroid and adrenocortical tumors?

Sporadic tumors of the pituitary, parathyroids and adrenal cortex are unique, as their benign forms are very common, but malignant forms are exceptionally rare. Hereditary forms of these tumors occur in multiple endocrine neoplasia syndrome type 1 (MEN1). We hypothesize that the pathogenic link among the sporadic tumors of these organs of different germ layers might be represented by common molecular pathways involving the MEN1 gene and microRNAs (miR). miR-24 might be a microRNA linking the three tumor entities, but other candidates such as miR-142-3p and microRNAs forming the DLK1-MEG3 miRNA cluster might also be of importance.

Why is microRNA action tissue specific? A putative defense mechanism against growth disorders, tumor development or progression mediated by circulating microRNA?

MicroRNAs as endogenous mediators of RNA interference and epigenetic regulation are involved in the regulation of numerous basic physiological processes. Both their expression and action is tissue specific, as microRNA target different messenger RNA molecules in different tissues and have various actions. MicroRNAs are major players in tumor development and act as oncogenes and tumor suppressors that also depend on the cellular context. MicroRNA are secreted and are present in the circulation, and circulating microRNA might affect gene expression in various cells. We present a hypothesis on the relevance of tissue specific microRNA action supposing that it might be a putative defense mechanism preventing secreted microRNA-mediated uniform gene expression changes (e.g. inducing cell proliferation or inhibiting apoptosis) and thus growth disorders, tumor development or progression that would occur if all cells and tissues would respond in the same way to circulating microRNA.

Possible role for microRNAs as inter-species mediators of epigenetic information in disease pathogenesis: is the non-coding dark matter of the genome responsible for epigenetic interindividual or interspecies communication?

MicroRNAs are short non-coding RNA molecules involved in the posttranscriptional epigenetic regulation of gene expression. Recent data show that microRNAs can be found in body fluids, and these microRNAs might enter cells giving rise to a hormone like way of action. MicroRNAs released in body fluids might affect other individuals, and there are some data of potential cross-species action of microRNAs, as well. Here, the authors discuss hypotheses concerning the potential pathogenic relevance of interindividual and cross-species action of microRNAs including food-derived microRNAs. Supposing that microRNAs might traverse the gastrointestinal tract, microRNAs might wander via the food-chain and even master regulatory microRNAs might be envisaged that could influence gene expression in a wide range of species and might thereby link different species via common gene expression signatures. Since many microRNA genes are located in the non-protein coding "dark matter" of the genome, a novel function of this "dark matter" is raised regarding interindividual and cross-species epigenetic communication via information transfer by gene products coded by the non-protein coding part of the genome.

In silico analysis of pathways affected by differentially expressed microRNA in adrenocortical tumors.

BACKGROUND: MicroRNA are involved in the pathogenesis of several tumors, and several studies have been performed on the microRNA profile of adrenocortical tumors to date. The pathways affected by these microRNA, however, have not been analyzed yet by a systematic approach. AIM: To perform an in silico bioinformatics analysis of microRNA commonly altered in at least two studies and to decipher the pathways affected by microRNA in adrenocortical tumors. METHODS: Datasets on microRNA and mRNA expression have been retrieved from 5 and 3 studies, respectively. MicroRNA mRNA targets have been identified by our tissue specific target prediction pipeline, and mRNA have been subjected to Ingenuity Pathway Analysis. RESULTS: Thirty- nine microRNA were identified as commonly altered in two studies. Altogether 49,817 mRNA targets have been found for these microRNA. One-hundred and seventy-eight significant pathways associating with these have been identified and were found in all studies. We have selected 12 pathways involving retinoic acid signaling (lipopolysaccharide/ interleukin-1 mediated inhibition of retinoic X receptor (RXR) function, peroxisome proliferator-activated receptor (PPAR)α/RXRα activation, retinoic A receptor activation and PPAR signaling pathways) and cell cycle alterations (aryl hydrocarbon receptor signaling, growth arrest and DNA damage-inducible 45 signaling, integrin signaling, G2/M DNA damage checkpoint regulation, cyclins and cell cycle regulation and cell cycle control of chromosomal replication pathways) as these have been also established in our previous study on the functional genomics meta-analysis of adrenocortical tumors. Several microRNA have been identified that could affect these pathways. CONCLUSIONS: MicroRNA might affect several pathogenic pathways in adrenocortical tumors. Validation studies are required to confirm the biological relevance of these findings.

Underexpression of C-myc in adrenocortical cancer: a major pathogenic event?

The protooncogene c-myc is a major factor in tumourigenesis. Whereas c-myc overexpression is considered to be a general feature of many tumours, we have recently demonstrated c-myc underexpression in adrenocortical cancer by a meta-analysis. We hypothesise that c-myc underexpression might be a central event in adrenortical tumourigenesis based on network topology modelling and previous experimental observations. In this brief hypothesis, we present our arguments and their possible relevance.

Meta-analysis of adrenocortical tumour genomics data: novel pathogenic pathways revealed.

Sporadic adrenocortical tumours are common, but their pathogenesis is poorly elucidated. In this study, we present a meta-analysis and review of gene expression microarray and comparative genome hybridization (CGH) studies performed to date on these tumours, including our own data. Data of whole genome microarray studies from altogether 164 tumours (97 benign, 67 malignant) and 18 normal tissues were reclassified and reanalysed. Significant gene sets and cytogenetic changes from publications without available genomic data were also examined including 269 benign, 215 malignant tumour and 30 normal tissues. In our experimental study, 11 tumour and four normal samples were analysed by parallel mRNA and CGH profiling. Data were examined by an integrative bioinformatics approach (GeneSpring, Gene Set Enrichment Analysis and Ingenuity Pathway Analysis softwares) searching for common gene expression changes and paralleling chromosome aberrations. Both meta-analysis of available mRNA and CGH profiling data and our experimental study revealed three major pathogenetic pathways: (1) cell cycle, (2) retinoic acid signalling (including lipopolysaccharide/Toll like receptor 4 pathway), (3) complement system and antigen presentation. These pathways include novel, previously undescribed pathomechanisms of adrenocortical tumours, and associated gene products may serve as diagnostic markers of malignancy and therapeutic targets.

Bone turnover in patients with endogenous Cushing's syndrome before and after successful treatment.

UNLABELLED: We investigated bone turnover and its restoration in a large number of patients in the active phase and after cure of endogenous Cushing's syndrome. Furthermore, the usefulness of serum osteocalcin and collagen breakdown products as potential markers of active Cushing's syndrome was also evaluated. INTRODUCTION: Suppressed bone formation is one of the most characteristic features of Cushing's syndrome (CS). Despite numerous previous reports, many aspects of the disturbed bone metabolism of these patients are unexplored. In this study, we investigated the time course of bone marker changes after the cure of CS as well as correlations between bone markers and serum cortisol concentrations. METHODS: Eighty-seven patients with CS were studied. Patients were followed up to 48 months after surgical cure. Serum osteocalcin (OC) and collagen breakdown products (CTX) were measured with immunochemiluminescence method and compared to the results of 161 healthy controls. RESULTS: OC showed a negative, while CTX displayed a positive correlation with serum cortisol. Patients with diabetes mellitus and myopathy had significantly lower serum OC levels compared to those without these complications. The area under the curve of OC obtained by receiver-operating characteristics analysis for the discrimination of patients with CS from healthy controls was 0.9227. Postoperative OC increased rapidly from the first few days or weeks reaching its maximum at the sixth month and remained stable after the 24th postoperative month. CONCLUSIONS: Our study demonstrated significant correlations between serum cortisol and both bone formation and resorption markers in the active phase of CS. We propose that OC may serve as a sensitive biologic marker of glucocorticoid activity in endogenous CS during its active phase and it may reflect the clinical cure of the disease.

Pharmacological options for treatment of hyperandrogenic disorders.

Hyperandrogenic disorders are frequent in women. The most common cause is polycystic ovary syndrome, a condition found up to 7% in women of reproductive age. The effects of testosterone and dihydrotestosterone are elicited via androgen receptors. Androgen receptor acts as a ligand-dependent transcription factor that regulates the expression of several target genes. There are several pharmacological possibilities for the treatment of androgen excess, as inhibition of the biologic activity of androgens can be carried out at different levels. The androgen receptor, the 5alpha-reductase enzyme, and the hypothalamic-pituitary-gonad axis are the most frequent targets of antiandrogenic therapies. This review summarizes the structural and chemical features of currently available antiandrogenic drugs, including cyproterone acetate, spironolactone, flutamide and finasteride. Also, it presents some recent advances in the chemistry and pharmacology of novel steroidal and non-steroidal antiandrogens, and 5alpha-reductase inhibitors. Finally, recent knowledge on non-classical antiandrogenic drugs, such as insulin-sensitizers, ketoconazole, and GnRH-agonists are briefly discussed.

Steroid biosynthesis inhibitors in the therapy of hypercortisolism: theory and practice.

Cushing's syndrome is a rare disease with significant morbidity and mortality. Surgical intervention represents the most effective treatment option in both adrenocorticotropin-dependent and -independent forms of hypercortisolism. It is not uncommon, however, that surgery fails to cure or control the disease. Pharmacotherapy with drugs inhibiting steroid biosynthesis can be effectively used in these cases in order to alleviate symptoms or even to induce chemical adrenalectomy. A few drugs inhibiting single or multiple steps in adrenal steroid biosynthesis can be used in clinical practice. Drugs predominantly inhibiting single enzymatic steps include the 11beta-hydroxylase inhibitor metyrapone and the 3beta-hydroxysteroid dehydrogenase inhibitor trilostane, whereas mitotane, aminoglutethimide, ketoconazole and etomidate block multiple enzymatic reactions. Etomidate is the only agent available for parenteral administration that renders it as a treatment of choice in critically ill patients requiring a rapid control of hypercortisolemia. Ketoconazole, metyrapone and aminoglutethimide can be used alone or in combination for the treatment of hypercortisolism caused by benign adrenocorticotropin- or cortisol-secreting tumors. The clinical utility of trilostane is variable. Besides blocking multiple steps in adrenal steroid biosynthesis, the DDT (insecticide) analogue mitotane also has adrenolytic properties by inducing mitochondrial degeneration that renders it superior to other drugs in the treatment of adrenocortical cancer. Severe side effects may develop during therapy with each aforementioned drug that include hepatic, endocrine and neurological toxicity. After summarizing the chemical and biological properties of steroid biosynthetic inhibitors, the authors describe their possible clinical applications and limitations.

[Genetics of multiple endocrine neoplasies: clinical implications]. / Génétique des néoplasies endocriniennes multiples: implications cliniques.

The multiple endocrine neoplasia (MEN) syndromes are hereditary monogenic diseases that are transmitted as autosomal dominant traits, and are characterized by the development of tumors and hyperplasias in several endocrine organs. The causative genes of the 2 principal forms of MEN have been recently identified; a protooncogene for MEN2 (the RET gene) and a tumor suppressor gene for MEN1 (the MEN1 gene). Correlations between phenotype and genotype were described in the case of RET mutations that could help in defining the screening methods and the preferable age of prophylactic thyroidectomy. No correlations were established between the mutations of the MEN1 gene and the phenotype of patients suffering from MEN1. We present here a synopsis of the recent results of the genetics of MEN syndromes underlining their clinical implications.

Segregation of the V804L mutation and S836S polymorphism of exon 14 of the RET gene in an extended kindred with familial medullary thyroid cancer.

In multiple endocrine neoplasia type 2A (MEN 2A) and familial medullary thyroid cancer (FMTC), the majority of germline mutations are restricted to specific positions in exons 10 and 11 of the RET gene. However, germline mutations may very occasionally occur in other exons, including exon 14 of the RET gene. Interestingly, an increased frequency of a rare germline sequence variant of the RET exon 14, S836S, has been detected in patients with sporadic medullary thyroid cancer (MTC), and this variant has been proposed to play a role in the genesis of MTC and, perhaps, FMTC. In this study we report the segregation of a germline V804L mutation and a germline sequence variant S836S in exon 14 of the RET gene in an extended Hungarian FMTC kindred comprising 80 individuals of four generations. Molecular analysis of the RET gene was performed by direct DNA sequencing in 23 family members, of whom 12 had the V804L mutation, three had the V804L mutation and S836S polymorphism in separate alleles, and six had the S836S polymorphism, all in heterozygous forms. Two of the family members had neither mutation nor polymorphism of the RET gene. Three of the family members who had the V804L mutation and one member who could not be tested for mutation were operated for non-metastatic MTC, while one member with MTC who had the V804L mutation refused surgery. In all patients affected with MTC, the disease developed relatively late in life and never caused death. None of the other family members carrying the V804L mutation and/or the S836S polymorphism had clinical or biochemical evidence of MTC. These observations suggest that the co-existence of the V804L mutation and S836S polymorphism in separate alleles does not seem to aggravate the relatively low-risk disease phenotype characteristic in most patients with codon 804 mutations of the RET exon 14.

Novel sequence variants of the genes associated with the multiple endocrine neoplasia syndromes 1 and 2. analysis by an "in silico approach.".

MEN syndromes (1 and 2) are hereditary tumor syndromes inherited as autosomal dominant traits. The genes that harbor the mutations responsible for the development of these syndromes have been cloned in recent years. In the present study we applied an "in silico" approach to find previously undescribed sequence variants of the RET protooncogene and the MEN1 gene. Sequence comparisons were performed at the National Center for Biotechnology Information Database by the search tool blastn. We found several sequence alterations in both coding and non-coding sequences. The majority of polymorphisms described to date were found by our approach, in addition we observed novel sequence variants of both genes as well. These sequence variants may have both diagnostic and theoretical relevance. In silico strategies may represent new, and potentially effective ways for finding novel sequence variants.

[Xenotransplantation of islets of Langerhans: a possible therapy for diabetes mellitus?]. / Die Xenotransplantation von Langerhans-Inseln: eine mögliche Therapie des Diabetes mellitus?

The current therapy of insulin-dependent (Type 1) diabetes mellitus is based on the lifelong application of exogenous insulin. Since the destruction of insulin-producing pancreatic islets is considered to be responsible for disease development, the transplantation of healthy islets could turn out to be the curative therapy of the disease. Unfortunately, numerous problems seem to be associated with the transplantation of islets of human origin. Therefore, xenotransplantation (the transplantation of organs/tissues of animal origin) could turn out to be an effective alternative treatment protocol. Some human trials have already been performed. In this brief review the author attempts to make a synopsis of the present perspectives and problems of islet xenotransplantation.

Biological and clinical significance of the JAK-STAT pathway; lessons from knockout mice.

Originally described as the signal-transducing pathway of interferons, the JAK-STAT pathway soon turned out to participate in the signalling of numerous other immune and even non-immune mediators. Several murine knockout models have been described that underline the biological significance of this signalling system. Some human diseases (mainly neoplastic) are also known where malfunctioning of the JAK-STAT pathway is considered to participate in the pathogenesis. In this brief review article we will try to make a synopsis of its biological and clinical significance.

C-terminal peptides of interleukin-6 modulate the expression of junB protooncogene and the production of fibrinogen by HepG2 cells.

Interleukin-6 (IL-6) is a 185 amino acid residue helical cytokine with various biological activities (e. g. B cell development, acute phase reaction). We have investigated the role of the 168-185 C-terminal region of IL-6 in the induction of fibrinogen synthesis and expression of junB mRNA using synthetic peptides corresponding to this region. Circular dichroism spectroscopy data suggest that even truncated peptides have a strong tendency to adopt an ordered conformation. Peptides were tested alone or in combination with recombinant hIL-6 on an IL-6 responsive human hepatoma HepG2 cell line. The expression of the protooncogene junB monitored by competitive RT-PCR represents an early, while the fibrinogen production detected by sandwich ELISA a late, marker of IL-6 initiated events. We found that peptides--depending on their structure--modulate spontaneous as well as IL-6 induced fibrinogen production and/or mRNA expression of junB by exhibiting inhibition (in the presence of IL-6) or stimulation (in the absence of IL-6).

Bidirectional communication between histamine and cytokines.

Histamine plays fundamental roles in numerous immune reactions. In addition to its well-characterized effects in the acute inflammatory and allergic responses, histamine also influences the expression and actions of several cytokines. The interaction between histamine and the cytokines is bidirectional, since some cytokines were found to modulate the production and release of histamine as well. Because several pharmacological agents that modulate the actions of histamine (e.g. antihistamines) are widely used in the treatment of various human diseases (allergy, peptic ulcer etc.), this complex interaction could have general medical relevance too, but the current situation appears to be rather controversial and further studies are needed to elucidate these sophisticated interactions more precisely.

[Antimicrobial peptides: a new way to treat bacterial infections]. / Antimikrobiális peptidek: új lehetóség a bakteriális fertózések leküzdésére?

The therapy of bacterial infections is currently a difficult problem of the contemporary medicine, mainly due to the increasing spread of resistance to conventional antibiotics and to the appearance of multi-resistant bacterial strains. Although the gene-encoded antimicrobial peptides were described for a while their intensive research and study of their possible clinical applications has started only in the recent years. These antimicrobial peptides appear to form part of the most ancient defense mechanisms of the phylogenesis by exerting cytotoxic (mainly membrane damaging) effects against many bacteria. In this review the author attempts to make a brief synopsis--from a medical point of view--of the most important antimicrobial peptides and their possible clinical applications.

[Drugs affecting apoptosis in the immune system]. / Az immunrendszeri apoptosisra ható gyógyszerek.

Apoptosis is a key feature in the physiological and pathological regulation of the immune system. Concerning its central immunoregulatory roles, it would be reasonable to attempt to influence the progression of autoimmune diseases by pharmacological intervention in the processes of apoptosis. Numerous compounds capable of influencing apoptosis are known, but their exact mechanisms of action are only in part understood. The majority of the known chemicals does not affect apoptosis selectively, but alters the function of the whole organism, therefore considerable side-effects related to the application of these compounds may appear. The complexity of this situation is indicated by findings that the same compound can either induce or inhibit apoptosis depending on the experimental system and concentration studied. Our knowledge will, presumably, be extended in the future that could lead to the safer clinical application of these compounds. In this brief review article we attempt to present a synopsis of the most important agents influencing apoptosis in the immune system from a clinical point of view.