Diana Rita Szabó

Analysis of circulating microRNAs in adrenocortical tumors

Differential diagnosis of adrenocortical adenoma (ACA) and carcinoma is of pivotal clinical relevance, as the prognosis and clinical management of benign and malignant adrenocortical tumors (ACTs) is entirely different. Circulating microRNAs (miRNAs) are promising biomarker candidates of malignancy in several tumors; however, there are still numerous technical problems associated with their analysis. The objective of our study was to investigate circulating miRNAs in ACTs and to evaluate their potential applicability as biomarkers of malignancy. We have also addressed technical questions including the choice of profiling and reference gene used. A total of 25 preoperative plasma samples obtained from patients with ACAs and carcinomas were studied by microarray and quantitative real-time PCR. None of the three miRNAs (hsa-miR-192, hsa-mir-197 and hsa-miR-1281) found as differentially expressed in plasma samples in our microarray screening could be validated by quantitative real-time PCR. In contrast, of the selected eight miRNAs reported in the literature as differentially expressed in ACT tissues, five (hsa-miR-100, hsa-miR-181b, hsa-miR-184, hsa-miR-210 and hsa-miR-483-5p) showed a statistically significant overexpression in adrenocortical cancer vs adenoma when normalized on hsa-miR-16 as a reference gene. Receiver operator characteristic analysis of data revealed that the combination of dCThsa-miR-210 - dCThsa-miR-181b and dCThsa-miR-100/dCThsa-miR-181b showed the highest diagnostic accuracy (area under curve 0.87 and 0.85, respectively). In conclusion, we have found significant differences in expression of circulating miRNAs between ACAs and carcinomas, but their diagnostic accuracy is not yet high enough for clinical application. Further studies on larger cohorts of patients are needed to assess the diagnostic and prognostic potential application of circulating miRNA markers.

Antitumoral effects of 9-cis retinoic acid in adrenocortical cancer

The currently available medical treatment options of adrenocortical cancer (ACC) are limited. In our previous meta-analysis of adrenocortical tumor genomics data, ACC was associated with reduced retinoic acid production and retinoid X receptor-mediated signaling. Our objective has been to study the potential antitumoral effects of 9-cis retinoic acid (9-cisRA) on the ACC cell line NCI-H295R and in a xenograft model. Cell proliferation, hormone secretion, and gene expression have been studied in the NCI-H295R cell line. A complex bioinformatics approach involving pathway and network analysis has been performed. Selected genes have been validated by real-time qRT-PCR. Athymic nude mice xenografted with NCI-H295R have been used in a pilot in vivo xenograft model. 9-cisRA significantly decreased cell viability and steroid hormone secretion in a concentration- and time-dependent manner in the NCI-H295R cell line. Four major molecular pathways have been identified by the analysis of gene expression data. Ten genes have been successfully validated involved in: (1) steroid hormone secretion (HSD3B1, HSD3B2), (2) retinoic acid signaling (ABCA1, ABCG1, HMGCR), (3) cell-cycle damage (GADD45A, CCNE2, UHRF1), and the (4) immune response (MAP2K6, IL1R2). 9-cisRA appears to directly regulate the cell cycle by network analysis. 9-cisRA also reduced tumor growth in the in vivo xenograft model. In conclusion, 9-cisRA might represent a promising new candidate in the treatment of hormone-secreting adrenal tumors and adrenocortical cancer.

Effects of mitotane on gene expression in the adrenocortical cell line NCI-H295R: A microarray study

AIM The adrenolytic agent mitotane is widely used in the treatment of adrenocortical cancer; however, its mechanism of action is poorly elucidated. We have studied mitotane-induced mRNA expression changes in the NCI-H295R adrenocortical cancer cell line. MATERIALS & METHODS Cell viability and hormone assays were used to select the optimal mitotane concentration effectively inhibiting hormone secretion without affecting cell viability. RNA isolated from cultures treated for 48 and 72 h was subjected to Agilent 4×44K microarray platforms. Microarray results were validated by quantitative reverse-transcription PCR. RESULTS Altogether, 117 significantly differentially expressed genes were detected at 48 h and 72 h (p < 0.05) in mitotane-treated samples relative to controls. Three significantly underexpressed genes involved in steroid hormone biosynthesis (HSD3B1, HSD3B2 and CYP21A2) and four significantly overexpressed genes (GDF15, ALDH1L2, TRIB3 and SERPINE2) have been validated. CONCLUSION Gene-expression changes might be involved in the adrenal action of mitotane and in the inhibition of hormone secretion.

Integrative analysis of neuroblastoma and pheochromocytoma genomics data

BackgroundPheochromocytoma and neuroblastoma are the most common neural crest-derived tumors in adults and children, respectively. We have performed a large-scale in silico analysis of altogether 1784 neuroblastoma and 531 pheochromocytoma samples to establish similarities and differences using analysis of mRNA and microRNA expression, chromosome aberrations and a novel bioinformatics analysis based on cooperative game theory.MethodsDatasets obtained from Gene Expression Omnibus and ArrayExpress have been subjected to a complex bioinformatics analysis using GeneSpring, Gene Set Enrichment Analysis, Ingenuity Pathway Analysis and own software.ResultsComparison of neuroblastoma and pheochromocytoma with other tumors revealed the overexpression of genes involved in development of noradrenergic cells. Among these, the significance of paired-like homeobox 2b in pheochromocytoma has not been reported previously. The analysis of similar expression patterns in neuroblastoma and pheochromocytoma revealed the same anti-apoptotic strategies in these tumors. Cancer regulation by stathmin turned out to be the major difference between pheochromocytoma and neuroblastoma. Underexpression of genes involved in neuronal cell-cell interactions was observed in unfavorable neuroblastoma. By the comparison of hypoxia- and Ras-associated pheochromocytoma, we have found that enhanced insulin like growth factor 1 signaling may be responsible for the activation of Src homology 2 domain containing transforming protein 1, the main co-factor of RET. Hypoxia induced factor 1α and vascular endothelial growth factor signaling included the most prominent gene expression changes between von Hippel-Lindau- and multiple endocrine neoplasia type 2A-associated pheochromocytoma.ConclusionsThese pathways include previously undescribed pathomechanisms of neuroblastoma and pheochromocytoma and associated gene products may serve as diagnostic markers and therapeutic targets.

Highly reduced peritoneal mast cell number and decreased c-kit expression in histidine decarboxylase knock out mice

Mast cells (MC) are one of the major effector cells in the pathogenesis of the immediate-type hypersensitivity reaction in many non-allergic diseases and also in normal physiological processes. Apart from this, it has been elucidated recently that mast cells also play a significant role in host responses to bacterial infections and in various forms of inflammatory reactions [1, 2]. MCs contain a series of biogenic amines, such as histamine and serotonin, and lipid mediators, including leukotrienes and prostaglandins. They also synthesize large quantities of specific proteinases, such as tryptases and chymase. MCs have multiple functions which arise in part from the phenomenon of mast cell heterogeneity, demonstrated through differences in histochemical, biochemical and functional characteristics. Many aspects of the mechanisms and local requirements of MC development and differentiation are still unknown, but local cytokine patterns and, contact interactions with bone marrow stroma cells are probably involved in the formation of MC subsets. In this study the role of histamine in the number and c-kit expression of MCs was examined, using a recently developed histamine deficient mouse model with a disrupted histidine decarboxylase gene.

Pathogenesis of adrenocortical cancer

Adrenocortical cancer is a rare tumor with poor prognosis. Whereas most cases occur in a sporadic setting, there are very rare hereditary forms that are important for the understanding of tumor pathogenesis. The hereditary syndromes associated with adrenocortical cancer are: Li-Fraumenis syndrome, Beckwith-Wiedemanns syndrome and familial adenomatous polyposis, whereas multiple endocrine neoplasia type 1, Carneys complex and McCune-Albrights syndrome mostly predispose to benign adrenocortical tumors. Overexpression of insulin like growth factor 2, activation of Wnt/beta-catenin and cAMP-protein kinase A signaling, as well as mutations of p53 and MEN1 genes are regarded as major pathogenetic mechanisms. Options for medical treatment of adrenocortical cancer are rather limited. Recently published molecular-bioinformatical studies have revealed several previously unknown pathogenetic pathways that may even represent potential drug targets. In this study, the pathogenesis of hereditary tumor syndromes, the alterations in sporadic tumors and the most recent molecular-bioinformatical observations are discussed.

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.

Relevance of long non-coding RNAs in tumour biology

The discovery of the biological relevance of non-coding RNA molecules represents one of the most significant advances in contemporary molecular biology. It has turned out that a major fraction of the non-coding part of the genome is transcribed. Beside small RNAs (including microRNAs) more and more data are disclosed concerning long non-coding RNAs of 200 nucleotides to 100 kb length that are implicated in the regulation of several basic molecular processes (cell proliferation, chromatin functioning, microRNA-mediated effects, etc.). Some of these long non-coding RNAs have been associated with human tumours, including H19, HOTAIR, MALAT1, etc., the different expression of which has been noted in various neoplasms relative to healthy tissues. Long non-coding RNAs may represent novel markers of molecular diagnostics and they might even turn out to be targets of therapeutic intervention.