Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterized in man by parathyroid, pancreatic, pituitary and adrenal tumours. The MEN1 gene encodes a 610-amino acid protein (menin) which is a tumour suppressor. To investigate the in vivo role of menin, we developed a mouse model, by deleting Men1 exons 1 and 2 and investigated this for MEN1-associated tumours and serum abnormalities. Men1 +/− mice were viable and fertile, and 220 Men1 +/− and 94 Men1 +/+ mice were studied between the ages of 3 and 21 months. Survival in Men1 +/− mice was significantly lower than in Men1 +/+ mice (<68% vs >85%, P<0.01). Men1 +/− mice developed, by 9 months of age, parathyroid hyperplasia, pancreatic tumours which were mostly insulinomas, by 12 months of age, pituitary tumours which were mostly prolactinomas, and by 15 months parathyroid adenomas and adrenal cortical tumours. Loss of heterozygosity and menin expression was demonstrated in the tumours, consistent with a tumour suppressor role for the Men1 gene. Men1 +/− mice with parathyroid neoplasms were hypercalcaemic and hypophosphataemic, with inappropriately normal serum parathyroid hormone concentrations. Pancreatic and pituitary tumours expressed chromogranin A (CgA), somatostatin receptor type 2 and vascular endothelial growth factor-A. Serum CgA concentrations in Men1 +/− mice were not elevated. Adrenocortical tumours, which immunostained for 3-β-hydroxysteroid dehydrogenase, developed in seven Men1 +/− mice, but resulted in hypercorticosteronaemia in one out of the four mice that were investigated. Thus, these Men1 +/− mice are representative of MEN1 in man, and will help in investigating molecular mechanisms and treatments for endocrine tumours.
Brian Harding, Manuel C Lemos, Anita A C Reed, Gerard V Walls, Jeshmi Jeyabalan, Michael R Bowl, Hilda Tateossian, Nicky Sullivan, Tertius Hough, William D Fraser, Olaf Ansorge, Michael T Cheeseman, and Rajesh V Thakker
P S H Soon, A J Gill, D E Benn, A Clarkson, B G Robinson, K L McDonald, and S B Sidhu
The management of adrenocortical tumors (ACTs) is complex. The Weiss score is the present most widely used system for ACT diagnosis. An ACT is scored from 0 to 9, with a higher score correlating with increased malignancy. However, ACTs with a score of 3 can be phenotypically benign or malignant. Our objective is to use microarray profiling of a cohort of adrenocortical carcinomas (ACCs) and adrenocortical adenomas (ACAs) to identify discriminatory genes that could be used as an adjunct to the Weiss score. A cohort of Weiss score defined ACCs and ACAs were profiled using Affymetrix HGU133plus2.0 genechips. Genes with high-discriminatory power were identified by univariate and multivariate analyses and confirmed by quantitative real-time reverse transcription PCR and immunohistochemistry (IHC). The expression of IGF2, MAD2L1, and CCNB1 were significantly higher in ACCs compared with ACAs while ABLIM1, NAV3, SEPT4, and RPRM were significantly lower. Several proteins, including IGF2, MAD2L1, CCNB1, and Ki-67 had high-diagnostic accuracy in differentiating ACCs from ACAs. The best results, however, were obtained with a combination of IGF2 and Ki-67, with 96% sensitivity and 100% specificity in diagnosing ACCs. Microarray gene expression profiling accurately differentiates ACCs from ACAs. The combination of IGF2 and Ki-67 IHC is also highly accurate in distinguishing between the two groups and is particularly helpful in ACTs with Weiss score of 3.
Cristina L Ronchi, Silviu Sbiera, Barbara Altieri, Sonja Steinhauer, Vanessa Wild, Michaela Bekteshi, Matthias Kroiss, Martin Fassnacht, and Bruno Allolio
Previous SNP array analyses have revealed genomic alterations of the Notch pathway as being the most frequent abnormality in adrenocortical tumors (ACTs). The aim of the present study was to evaluate the expression of components of Notch signaling in ACTs and to correlate them with clinical outcome. The mRNA expression of JAG1, NOTCH1, and selected target genes of NOTCH1 (HES1, HES5, and HEY2) was evaluated in 80 fresh frozen samples (28 normal adrenal glands (NAGs), 24 adenomas (ACAs), and 28 carcinomas (ACCs)) by quantitative RT-PCR. Immunohistochemistry was performed in 221 tissues on paraffin slides (16 NAGs, 27 ACAs, and 178 ACCs) for JAG1, activated NOTCH1 (aNOTCH1), and HEY2. An independent ACC validation cohort (n=77) was then also investigated. HEY2 mRNA expression was higher in ACCs than it was in ACAs (P<0.05). The protein expression of all of the factors was high (H-score 2–3) in a larger proportion of ACCs as compared to ACAs and NAGs (JAG1 in 27, 15, and 10%; aNOTCH1 in 13, 8, and 0%; HEY2 in 66, 61, and 33% respectively, all P<0.001). High JAG1 expression was associated with earlier tumor stages and lower numbers of metastases in ACCs (both P=0.08) and favorably impacted overall and progression-free survival (PFS) (131 vs 30 months, hazard ratio (HR) 0.45, and 37 vs 9 months, HR 0.51, both P<0.005). This impact on overall survival (OS) was confirmed in the validation cohort. No such association was observed for aNOTCH1 or HEY2. In conclusion, different components of the Notch1 signaling pathway are overexpressed in ACCs, which suggests a role for the pathway in malignant transformation. However, JAG1 is overexpressed in a subgroup of ACCs with a better clinical outcome.
Zsófia Tömböl, Peter M Szabó, Viktor Molnár, Zoltán Wiener, Gergely Tölgyesi, János Horányi, Peter Riesz, Peter Reismann, Attila Patócs, István Likó, Rolf-Christian Gaillard, András Falus, Károly Rácz, and Peter Igaz
MicroRNAs (miRs) are involved in the pathogenesis of several neoplasms; however, there are no data on their expression patterns and possible roles in adrenocortical tumors. Our objective was to study adrenocortical tumors by an integrative bioinformatics analysis involving miR and transcriptomics profiling, pathway analysis, and a novel, tissue-specific miR target prediction approach. Thirty-six tissue samples including normal adrenocortical tissues, benign adenomas, and adrenocortical carcinomas (ACC) were studied by simultaneous miR and mRNA profiling. A novel data-processing software was used to identify all predicted miR–mRNA interactions retrieved from PicTar, TargetScan, and miRBase. Tissue-specific target prediction was achieved by filtering out mRNAs with undetectable expression and searching for mRNA targets with inverse expression alterations as their regulatory miRs. Target sets and significant microarray data were subjected to Ingenuity Pathway Analysis. Six miRs with significantly different expression were found. miR-184 and miR-503 showed significantly higher, whereas miR-511 and miR-214 showed significantly lower expression in ACCs than in other groups. Expression of miR-210 was significantly lower in cortisol-secreting adenomas than in ACCs. By calculating the difference between dCTmiR-511 and dCTmiR-503 (delta cycle threshold), ACCs could be distinguished from benign adenomas with high sensitivity and specificity. Pathway analysis revealed the possible involvement of G2/M checkpoint damage in ACC pathogenesis. To our knowledge, this is the first report describing miR expression patterns and pathway analysis in sporadic adrenocortical tumors. miR biomarkers may be helpful for the diagnosis of adrenocortical malignancy. This tissue-specific target prediction approach may be used in other tumors too.
Cristina L Ronchi, Silviu Sbiera, Luitgard Kraus, Sebastian Wortmann, Sarah Johanssen, Patrick Adam, Holger S Willenberg, Stefanie Hahner, Bruno Allolio, and Martin Fassnacht
Therapeutic progress in adrenocortical carcinoma (ACC) is severely hampered by its low incidence. Platinum-based chemotherapies are the most effective cytotoxic treatment regimens in ACC but response rates remain <50%. In other tumor entities, expression of excision repair cross complementing group 1 (ERCC1) predicts resistance to platinum compounds. Therefore, we correlated ERCC1 protein expression and clinical outcome. We have retrolectively established adrenal tissue microarrays and analyzed prospectively samples from 163 ACCs, 15 benign adrenal adenomas, and 8 normal adrenal glands by immunohistochemistry for ERCC1 protein expression. Detailed clinical data were available by the German ACC Registry. ERCC1 protein was highly expressed in all normal adrenal glands, 14 benign tumors (93%) and in 75 ACCs (47%). In ACC, no differences in baseline parameters were found between patients with and without ERCC1 expression. Detection of ERCC1 was not correlated with survival in patients who never received platinum-based chemotherapy. In platinum-treated patients (n=45), objective response to platinum compounds was observed in 3/21 patients (14.3%) with high ERCC1 expression and in 7/24 patients (29.2%) with low ERCC1 expression (P=0.23). ERCC1 expression was strongly correlated with overall survival after platinum treatment (median: eight months in patients with high ERCC1 versus 24 months in low ERCC1 expression, hazard ratio (HR) 2.95 (95% confidence interval (CI) 1.4–6.2), P=0.004). Multivariate analysis confirmed that high ERCC1 expression was a predictive factor for poor prognosis in platinum treated patients (HR 2.2, 95% CI 1.0–4.5, P=0.038). Our findings suggest that ERCC1 expression is the first factor for predicting survival in ACC patients treated with platinum-based chemotherapy.
Stephanie Espiard, Ludivine Drougat, Nikolaos Settas, Sara Haydar, Kerstin Bathon, Edra London, Isaac Levy, Fabio R Faucz, Davide Calebiro, Jérôme Bertherat, Dong Li, Michael A Levine, and Constantine A Stratakis
Genetic variants in components of the protein kinase A (PKA) enzyme have been associated with various defects and neoplasms in the context of Carney complex (CNC) and in isolated cases, such as in primary pigmented nodular adrenocortical disease (PPNAD), cortisol-producing adrenal adenomas (CPAs), and various cancers. PRKAR1A mutations have been found in subjects with impaired cAMP-dependent signaling and skeletal defects; bone tumors also develop in both humans and mice with PKA abnormalities. We studied the PRKACB gene in 148 subjects with PPNAD and related disorders, who did not have other PKA-related defects and identified two subjects with possibly pathogenic PRKACB gene variants and unusual bone and endocrine phenotypes. The first presented with bone and other abnormalities and carried a de novo c.858_860GAA (p.K286del) variant. The second subject carried the c.899C>T (p.T300M or p.T347M in another isoform) variant and had a PPNAD-like phenotype. Both variants are highly conserved in the PRKACB gene. In functional studies, the p.K286del variant affected PRKACB protein stability and led to increased PKA signaling. The p.T300M variant did not affect protein stability or response to cAMP and its pathogenicity remains uncertain. We conclude that PRKACB germline variants are uncommon but may be associated with phenotypes that resemble those of other PKA-related defects. However, detailed investigation of each variant is needed as PRKACB appears to be only rarely affected in these conditions, and variants such as p.T300M maybe proven to be clinically insignificant, whereas others (such as p.K286del) are clearly pathogenic and may be responsible for a novel syndrome, associated with endocrine and skeletal abnormalities.
Meenu Jain, Lisa Zhang, Mei He, Ya-Qin Zhang, Min Shen, and Electron Kebebew
Adrenocortical carcinoma (ACC) is a rare but aggressive malignancy with no effective therapy for patients with unresectable disease. The aim of the current study was i) to evaluate TOP2A expression and function in human adrenocortical neoplasm and ACC cells and ii) to determine the anticancer activity of agents that target TOP2A. TOP2A mRNA and protein expression levels were evaluated in 112 adrenocortical tissue samples (21 normal adrenal cortex, 80 benign adrenocortical tumors, and 11 ACCs). In vitro siRNA knockdown of TOP2A in ACC cell lines (NCI-H295R and SW13) was used to determine its effect on cellular proliferation, cell cycle, anchorage-independent growth, and cellular invasion. We screened 14 TOP2A inhibitors for their anticancer activity in ACC cells. TOP2A mRNA and protein expression was significantly higher in ACC than in benign and normal adrenocortical tissue samples (P<0.05). Knockdown of TOP2A gene expression in ACC cell lines significantly decreased cell proliferation, anchorage-independent growth, and invasion (P<0.05). A screening assay in NCI-H295R cells showed that 11 of 14 TOP2A inhibitors had antiproliferative activity, 5 of the 14 TOP2A inhibitors had a higher antiproliferative activity than mitotane, and aclarubicin was the agent with the highest activity. Aclarubicin was validated to significantly decrease proliferation and tumor spheroid size in both NCI-H295R and SW13 ACC cell lines (P<0.05). Our results suggest that TOP2A is overexpressed in ACC, regulates cellular proliferation and invasion in ACC cells, and is an attractive target for ACC therapy. Of the TOP2A inhibitors screened, aclarubicin is a good candidate agent to test in future clinical trials for patients with locally advanced and metastatic ACC.
Kate M Warde, Erik Schoenmakers, Eduardo Ribes Martinez, Yi Jan Lim, Maeve Leonard, Sarah J Lawless, Paula O’Shea, Krishna V Chatterjee, Mark Gurnell, Constanze Hantel, and Michael Conall Dennedy
Adrenocortical carcinoma (ACC) is a rare aggressive malignancy with a poor outcome largely due to limited treatment options. Here, we propose a novel therapeutic approach through modulating intracellular free cholesterol via the liver X receptor alpha (LXRα) in combination with current first-line pharmacotherapy, mitotane. H295R and MUC-1 ACC cell lines were pretreated with LXRα inhibitors in combination with mitotane. In H295R, mitotane (20, 40 and 50 µM) induced dose-dependent cell death; however, in MUC-1, this only occurred at a supratherapeutic concentration (200 µM). LXRα inhibition potentiated mitotane-induced cytotoxicity in both cell lines. This was confirmed through use of the CompuSyn model which showed moderate pharmacological synergism and was indicative of apoptotic cell death via an increase in annexinV and cleaved-caspase 3 expression. Inhibition of LXRα was confirmed through downregulation of cholesterol efflux pumps ABCA1 and ABCG1; however, combination treatment with mitotane attenuated this effect. Intracellular free-cholesterol levels were associated with increased cytotoxicity in H295R (r 2 = 0.5210) and MUC-1 (r 2 = 0.9299) cells. While both cell lines exhibited similar levels of free cholesterol at baseline, H295R were cholesterol ester rich, whereas MUC-1 were cholesterol ester poor. We highlight the importance of LXRα mediated cholesterol metabolism in the management of ACC, drawing attention to its role in the therapeutics of mitotane sensitive tumours. We also demonstrate significant differences in cholesterol storage between mitotane sensitive and resistant disease.
Stefano Caramuta, Linkiat Lee, Deniz M Özata, Pinar Akçakaya, Hong Xie, Anders Höög, Jan Zedenius, Martin Bäckdahl, Catharina Larsson, and Weng-Onn Lui
Deregulation of microRNA (miRNA) expression in adrenocortical carcinomas (ACCs) has been documented to have diagnostic, prognostic, as well as functional implications. Here, we evaluated the mRNA expression of DROSHA, DGCR8, DICER (DICER1), TARBP2, and PRKRA, the core components in the miRNA biogenesis pathway, in a cohort of 73 adrenocortical tumors (including 43 adenomas and 30 carcinomas) and nine normal adrenal cortices using a RT-qPCR approach. Our results show a significant over-expression of TARBP2, DICER, and DROSHA in the carcinomas compared with adenomas or adrenal cortices (P<0.001 for all comparisons). Using western blot and immunohistochemistry analyses, we confirmed the higher expression of TARBP2, DICER, and DROSHA at the protein level in carcinoma cases. Furthermore, we demonstrate that mRNA expression of TARBP2, but not DICER or DROSHA, is a strong molecular predictor to discriminate between adenomas and carcinomas. Functionally, we showed that inhibition of TARBP2 expression in human NCI-H295R ACC cells resulted in a decreased cell proliferation and induction of apoptosis. TARBP2 over-expression was not related to gene mutations; however, copy number gain of the TARBP2 gene was observed in 57% of the carcinomas analyzed. In addition, we identified that miR-195 and miR-497 could directly regulate TARBP2 and DICER expression in ACC cells. This is the first study to demonstrate the deregulation of miRNA-processing factors in adrenocortical tumors and to show the clinical and biological impact of TARBP2 over-expression in this tumor type.
Ségolène Hescot, Abdelhamid Slama, Anne Lombès, Angelo Paci, Hervé Remy, Sophie Leboulleux, Rita Chadarevian, Séverine Trabado, Larbi Amazit, Jacques Young, Eric Baudin, and Marc Lombès
Mitotane, 1,1-dichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane is the most effective medical therapy for adrenocortical carcinoma, but its molecular mechanism of action remains poorly understood. Although mitotane is known to have mitochondrial (mt) effects, a direct link to mt dysfunction has never been established. We examined the functional consequences of mitotane exposure on proliferation, steroidogenesis, and mt respiratory chain, biogenesis and morphology, in two human adrenocortical cell lines, the steroid-secreting H295R line and the non-secreting SW13 line. Mitotane inhibited cell proliferation in a dose- and a time-dependent manner. At the concentration of 50 μM (14 mg/l), which corresponds to the threshold for therapeutic efficacy, mitotane drastically reduced cortisol and 17-hydroxyprogesterone secretions by 70%. This was accompanied by significant decreases in the expression of genes encoding mt proteins involved in steroidogenesis (STAR, CYP11B1, and CYP11B2). In both H295R and SW13 cells, 50 μM mitotane significantly inhibited (50%) the maximum velocity of the activity of the respiratory chain complex IV (cytochrome c oxidase (COX)). This effect was associated with a drastic reduction in steady-state levels of the whole COX complex as revealed by blue native PAGE and reduced mRNA expression of both mtDNA-encoded COX2 (MT-CO2) and nuclear DNA-encoded COX4 (COX4I1) subunits. In contrast, the activity and expression of respiratory chain complexes II and III were unaffected by mitotane treatment. Lastly, mitotane exposure enhanced mt biogenesis (increase in mtDNA content and PGC1 α (PPARGC1A) expression) and triggered fragmentation of the mt network. Altogether, our results provide first evidence that mitotane induced a mt respiratory chain defect in human adrenocortical cells.