MicroRNA expression profiling in benign (sporadic and hereditary) and recurring adrenal pheochromocytomas

Abstract

MicroRNAs are involved in the pathogenesis of several tumors, however, there have been no data on microRNA expression in pheochromocytomas to date. The objective of our study was to perform microRNA expression profiling in sporadic and hereditary benign, and recurring adrenomedullary tumors. Furthermore, the applicability of formalin-fixed paraffin-embedded tissue samples for the analysis of microRNA expression in pheochromocytomas was examined. MicroRNA expression data of three matched frozen and formalin-fixed paraffin-embedded samples were correlated. A total of 21 formalin-fixed paraffin-embedded samples (sporadic benign, multiple endocrine neoplasia 2, von Hippel-Lindau disease, sporadic recurring) were subjected to microRNA expression profiling using microarrays. MicroRNAs with significant differences in expression were validated and sample sizes were extended including tumors from neurofibromatosis type 1 patients by real-time quantitative reverse-transcription PCR (n ¼ 33). MicroRNA target prediction was carried out by TargetScan and MicroCosm Targets. Pathway analysis of targets was performed by Ingenuity Pathway Analysis and DIANA mirPath. Furthermore, microRNA expression profiles of a malignant pheochromocytoma and a pair of primary and recurrent tumors were studied by TaqMan Human MicroRNA Cards. MicroRNA expression correlated well between frozen and formalin-fixed paraffinembedded samples (70-92%). Microarray analysis revealed 16 significantly differentially expressed microRNAs. Five of these were validated by real-time RT-PCR. miR-139-3p, miR-541 and miR-765 were significantly differentially expressed between sporadic benign and von Hippel-Lindau-related pheochromocytomas. Significantly higher expression of miR-885-5p and miR-1225-3p was found in multiple endocrine neoplasia type 2 and sporadic recurring pheochromocytomas, respectively. Pathway analysis revealed the possible involvement of Notch-and G-proteincoupled receptor signaling in tumor recurrence. MicroRNA expression profiles in the primary recurrent and recurring malignant comparisons have been similar. In conclusion, we have proved that formalin-fixed paraffinembedded samples can be used for the analysis of microRNA expression in pheochromocytomas. MicroRNA expression patterns differ between various sporadic, hereditary and recurring tumors and miR-1225-3p may be useful for identifying recurring pheochromocytomas.

MicroRNAs in adrenal tumors: relevance for pathogenesis, diagnosis, and therapy

“…Overexpression of hypoxia-related miR-210 was found in pseudohypoxia-associated highly vascularized SDHB-and VHL-associated tumors [71]. Overexpression of miR-139-3p, miR-541, miR-765, and miR-133b have been found characteristic for VHL tumors [71,72]. Overexpressed miR-96 [71] and miR-183 [71,73] was described in SDHB-associated pheochromocytomas, and the transfection of these two microRNAs hampered the nerve growth factor (NGF)-induced differentiation of rat PC12 cells in vitro [70].…”

Integrative analysis of miRNA and mRNA expression profiles in pheochromocytoma and paraganglioma identifies genotype-specific markers and potentially regulated pathways

“…Of our reduced list of candidates, eight miRNAs specific to or common among genetic group(s) were identified and validated in this study. Among them, upregulation of miR-885-5p and miR-488 was unique to RET-related PCCs/PGLs; the former miRNA was also described by Tombol et al (2010) as a RET-specific miRNA and reported to suppress cell migration through modulation of focal adhesion activity (Song et al 2011). In neuroblastoma, miR-885-5p has been reported as a tumor suppressor gene, which targets cyclin-dependent kinase 2 (CDK2) and mini-chromosome maintenance protein 5 (MCM5) (Afanasyeva et al 2011).…”

“…miRNAs bind to semi-complimentary sites at the 3 0 -UTR of targeted mRNA, which can result in mRNA degradation and/or translational truncation (Bartel 2004, Lim et al 2005, and thus can affect gene expression. To date, three miRNA expression profiling studies have been performed on PCCs/PGLs (Meyer-Rochow et al 2010, Tombol et al 2010, Patterson et al 2012. This study identifies for the first time miRNA expression levels in seven genetic classes of PCCs/PGLs (VHL, SDHB, SDHD, RET, NF1, TMEM127, and MAX mutants), which were validated in an independent series.…”

Circulating tumor cells and miRNAs as prognostic markers in neuroendocrine neoplasms

“…This issue is extremely important as there are no reliable histologic or molecular markers that allow distinguishing benign from malignant PCs. Tombol and coworkers (Tombol et al 2010) evaluated 34 PC cases including 9 sporadic benign, 5 sporadic recurrent tumors, 8 lesions in the settings of multiple endocrine neoplasia type 2, 6 associated with von Hippel Lindau disease, 5 with type 1 neurofibromatosis and 1 malignant PC. They observed that miR-1225-3p levels are higher in sporadic recurrent as compared to sporadic non-recurrent PC, providing a threshold value for miR-1225-3p also that identified a PC as recurrent with good sensitivity and specificity.…”