Protein enzymatic changes of the cAMP pathway and microRNA aberrations in the pathogenesis of adrenocortical tumors

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2008 (EN)
Ενζυματικές αλλαγές στο cAMP μονοπάτι σηματοδότησης και αλλαγές στην έκφραση των microRNA στην παθογένεση των όγκων του φλοιού των επινεφριδίων
Protein enzymatic changes of the cAMP pathway and microRNA aberrations in the pathogenesis of adrenocortical tumors

Μπιμπάκη, Ειρήνη Ι

Στρατάκης, Κωνσταντίνος

Context Bilateral adrenal hyperplasias (BAHs) may be caused by mutations of genes that code for molecules that participate in cAMP signaling. Little is known about cAMP signaling in adrenocortical tumors (ADTs) that do not harbor mutations in known genes. Massive macronodular adrenocortical disease (MMAD) and Primary pigmented adrenocortical disease (PPNAD), two forms of BAHs may be caused by aberrant microRNA expression. Objective We assessed the cAMP signaling pathway by enzymatic and molecular studies in mutation-negative ADTs. Furthermore, we were interested in identifying the microRNA profile in MMAD and PPNAD and in detecting putative microRNAgene target pairs involved in adrenal tumorigenesis. Design Samples from 27 patients with ADTs (ages 5-60 years) were studied and compared to normal adrenocortical tissue. All samples were sequenced for GNAS, PRKAR1A, PDE11A, and PDE8B sequencing defects. Cyclic AMP (cAMP) levels and binding, protein kinase A (PKA), and phosphodiesterase (PDE) activities were assayed. Additionally, 10 patients with MMAD (ages 39 - 60 years) and 10 patients with PPNAD (ages 5-41 years) were studied in order to identify the microRNA profile; 4 normal adrenal cortices were used as controls. All samples were analyzed using microRNA microarrays; data were validated by Real Time PCR. MicroRNA microarray analysis was integrated with expression data in the same MMAD, PPNAD samples to identify potential microRNA-gene target pairs implicated in adrenal hyperplasia formation. Using a PPNAD cell line we tried to investigate the regulatory mechanisms underlying the expression of miR-449. Results All adenomas were mutation-negative; these tumors had lower PDE activity levels and higher cAMP binding affinity than normal adrenal. BAHs, both with and without any mutations, had higher cAMP levels and decreased free PKA activity. A total of 37 microRNAs, 44 microRNAs were differentially expressed between MMAD, PPNAD and normal tissues respectively. We also identified putative gene targets for these microRNAs. After considering various clinical parameters from our patients, we identified miR-130a and miR-382 as putative diagnostic markers in MMAD and let-7b in PPNAD. We demonstrate a regulatory mechanism according to which PKA modulates the expression of miR-449 and its target gene WISP2. Conclusion: ADTs independently of their mutation status, demonstrated functional abnormalities of cAMP signaling. It is probable that epigenetic events, microRNA - 8 - implication or additional defects of genes involved in this pathway are responsible. MicroRNAs appear to have distinct regulatory effects in MMAD and PPNAD, including an association with clinical presentation and severity of the disease. MicroRNAs are modulators of the Wnt signaling pathway, indicating a novel pathogenetic mechanism in adrenal tumorigenesis. (EN)

Τύπος Εργασίας--Μεταπτυχιακές εργασίες ειδίκευσης

Νοσήματα φλοιού επινεφριδίων
Adrenal Cortex Diseases



Σχολή/Τμήμα--Ιατρική Σχολή--Τμήμα Ιατρικής--Μεταπτυχιακές εργασίες ειδίκευσης

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