This review describes the molecular alterations observed in the various types of tumors of the adrenal cortex, excluding Conn adenomas, especially the alterations identified by genomic approaches these last five years. Two main forms of bilateral adrenocortical tumors can be distinguished according to size and aspect of the nodules: primary pigmented nodular adrenal disease (PPNAD), which can be sporadic or part of Carney complex and primary bilateral macro nodular adrenal hyperplasia (PBMAH). The bilateral nature of the tumors suggests the existence of an underlying genetic predisposition. PPNAD and Carney complex are mainly due to germline-inactivating mutations of PRKAR1A, coding for a regulatory subunit of PKA, whereas PBMAH genetic seems more complex. However, genome-wide approaches allowed the identification of a new tumor suppressor gene, ARMC5, whose germline alteration could be responsible for at least 25% of PBMAH cases. Unilateral adrenocortical tumors are more frequent, mostly adenomas. The Wnt/beta-catenin pathway can be activated in both benign and malignant tumors by CTNNB1 mutations and by ZNRF3 inactivation in adrenal cancer (ACC). Some other signaling pathways are more specific of the tumor dignity. Thus, somatic mutations of cAMP/PKA pathway genes, mainly PRKACA, coding for the catalytic alpha-subunit of PKA, are found in cortisol-secreting adenomas, whereas IGF-II overexpression and alterations of p53 signaling pathway are observed in ACC. Genome-wide approaches including transcriptome, SNP, methylome and miRome analysis have identified new genetic and epigenetic alterations and the further clustering of ACC in subgroups associated with different prognosis, allowing the development of new prognosis markers.
Fidéline Bonnet-Serrano and Jérôme Bertherat
Kiran Nadella, Fabio R Faucz, and Constantine A Stratakis
Protein kinase A (PKA) regulatory subunit type 1A (PRKAR1A) defects lead to primary pigmented nodular adrenocortical disease (PPNAD). The KIT protooncogene (c-KIT) is not known to be expressed in the normal adrenal cortex (AC). In this study, we investigated the expression of c-KIT and its ligand, stem cell factor (SCF), in PPNAD and other cortisol-producing tumors of the adrenal cortex. mRNA and protein expression, by qRT-PCR, immunohistochemistry (IHC) and immunoblotting (IB), respectively, were studied. We then tested c-KIT and SCF responses to PRKAR1A introduction and PKA stimulation in adrenocortical cell lines CAR47 and H295R, which were also treated with the KIT inhibitor, imatinib mesylate (IM). Mice xenografted with H295R cells were treated with IM. There was increased c-KIT mRNA expression in PPNAD; IHC showed KIT and SCF immunoreactivity within certain nodular areas in PPNAD. IB data was consistent with IHC and mRNA data. PRKAR1A-deficient CAR47 cells expressed c-KIT; this was enhanced by forskolin and lowered by PRKAR1A reintroduction. Knockdown of PKA’s catalytic subunit (PRKACA) by siRNA reduced c-KIT levels. Treatment of the CAR47 cells with IM resulted in reduced cell viability, growth arrest, and apoptosis. Treatment with IM of mice xenografted with H295 cells inhibited further tumor growth. We conclude that c-KIT is expressed in PPNAD, an expression that appears to be dependent on PRKAR1A and/or PKA activity. In a human adrenocortical cell line and its xenografts in mice, c-KIT inhibition decreased growth, suggesting that c-KIT inhibitors may be a reasonable alternative therapy to be tested in PPNAD, when other treatments are not optimal.
Barbara Mariniello, Antonio Rosato, Gaia Zuccolotto, Beatrice Rubin, Maria Verena Cicala, Isabella Finco, Maurizio Iacobone, Anna Chiara Frigo, Ambrogio Fassina, Raffaele Pezzani, and Franco Mantero
Treatment options are insufficient in patients with adrenocortical carcinoma (ACC). Based on the efficacy of sorafenib, a tyrosine kinase inhibitor, and everolimus, an inhibitor of the mammalian target of rapamycin in tumors of different histotype, we aimed at testing these drugs in adrenocortical cancer models. The expression of vascular endothelial growth factor and its receptors (VEGFR1–2) was studied in 18 ACCs, 33 aldosterone-producing adenomas, 12 cortisol-producing adenomas, and six normal adrenal cortex by real-time PCR and immunohistochemistry and by immunoblotting in SW13 and H295R cancer cell lines. The effects of sorafenib and everolimus, alone or in combination, were tested on primary adrenocortical cultures and SW13 and H295R cells by evaluating cell viability and apoptosis in vitro and tumor growth inhibition of tumor cell line xenografts in immunodeficient mice in vivo. VEGF and VEGFR1–2 were detected in all samples and appeared over-expressed in two-thirds of ACC specimens. Dose-dependent inhibition of cell viability was observed particularly in SW13 cells after 24 h treatment with either drug; drug combination produced markedly synergistic growth inhibition. Increasing apoptosis was observed in tumor cells treated with the drugs, particularly with sorafenib. Finally, a significant mass reduction and increased survival were observed in SW13 xenograft model undergoing treatment with the drugs in combination. Our data suggest that an autocrine VEGF loop may exist within ACC. Furthermore, a combination of molecularly targeted agents may have both antiangiogenic and direct antitumor effects and thus could represent a new therapeutic tool for the treatment of ACC.
L Cerquetti, B Bucci, R Marchese, S Misiti, U De Paula, R Miceli, A Muleti, D Amendola, P Piergrossi, E Brunetti, V Toscano, and A Stigliano
Mitotane, 1,1-dichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane (o,p′-DDD) is an agent with adrenotoxic effect, which is able to block cortisol synthesis. This drug and radiotherapy are used also in adrenal cancer treatment even if their biological action in this neoplasia remains unknown. We investigated the effects of o,p′-DDD and ionizing radiations (IR) on cell growth inhibition and cell cycle perturbation in H295R and SW13 adrenocortical cancer cells. Both cell lines were irradiated at a 6 Gy dose and were treated with o,p′-DDD 10−5 M separately and with IR/o,p′-DDD in combination. This combination treatment induced an irreversible inhibition of cell growth in both adrenocortical cancer cells. Cell cycle analysis showed that IR alone and IR/o,p′-DDD in combination induced the cell accumulation in the G2 phase. At 120 h after IR, the cells were able to recover the IR-induced G2 block while cells treated with IR/o,p′-DDD were still arrested in G2 phase. In order to study the molecular mechanism involved in the G2 irreversible arrest, we have considered the H295R cell line showing the highest inhibition of cell proliferation associated with a noteworthy G2 arrest. In these cells, cyclin B1 and Cdk2 proteins were examined by western blot and Cdk2 kinase activity measured by assay kit. The H295R cells treated with IR/o,p′-DDD shared an increase in cyclin B1 amount as the coimmunoprecipitation of Cdc2–cyclin B1 complex. The kinase activity also shows an increase in the treated cells with combination therapy. Moreover, in these cells, sequence analysis of p53 revealed a large deletion of exons 8 and 9. The same irreversible block on G2 phase, induced by IR/o,p′-DDD treatment, happened in H295R cells with restored wild-type p53 suggesting that this mechanism is not mediated by p53 pathway.
Rossella Libè, Amato Fratticci, and Jérôme Bertherat
Adrenocortical cancer (ACC) is a rare tumor with a poor prognosis. By contrast, benign adrenocortical tumors are frequent, underlying the importance of a correct diagnosis of malignancy of such tumors. ACC can be diagnosed by the investigation of endocrine signs of steroid excess, symptoms due to tumor growth or an adrenal incidentaloma. Hormonal investigations demonstrate in most ACC steroid oversecretion, the dominant characteristics being a co-secretion of cortisol and androgens. Imaging by CT-scan or MRI shows a large heterogeneous tumor with a low fat content. Careful pathological investigation with the assessment of the Weiss score is important for the diagnosis of malignancy. Molecular markers can also be helpful and in the future might be important for prognosis. Tumors localized to the adrenal gland (McFarlane stages 1 and 2) have a better outcome than invasive and metastatic tumors (stages 3 and 4). Tumor removal by a specialized team is crucial for treatment and should always aim at complete removal. In patients with metastatic or progressive disease, medical treatment is started with mitotane that requires a close monitoring of its blood level. Surgery is indicated when possible for local recurrence but also in some cases of metastasis. Local treatment (radiofrequency, chemoembolization, and radiation therapy) can have some indications for metastatic disease. In patients with disease progression cytotoxic chemotherapy can be used. Despite the best care, the overall prognosis of ACC is poor with a 5-year survival rate below 30% in most series. Therefore, progress in the understanding of the pathophysiology of ACC is important. Despite the rarity of ACC, significant advances have been made in the understanding of its pathogenesis the last decade. These progresses came mainly from the study of the genetics of ACC, both at the germline level in rare familial diseases, and at the somatic level by the study of molecular alterations in sporadic tumors. These advances underline the importance of genetic alterations in ACC development and point-out to various chromosomal regions (2, 11p15, 11q, 17p13) and genes (IGF-II, p53, β-catenin, ACTH receptor). This review will summarize these advances as well as the current clinical management of ACC.
M J Reed, R W Cheng, P A Beranek, and V H T James
A L Ogilvy-Stuart and S M Shalet
Laura C Hernández-Ramírez, Ryhem Gam, Nuria Valdés, Maya B Lodish, Nathan Pankratz, Aurelio Balsalobre, Yves Gauthier, Fabio R Faucz, Giampaolo Trivellin, Prashant Chittiboina, John Lane, Denise M Kay, Aggeliki Dimopoulos, Stephan Gaillard, Mario Neou, Jérôme Bertherat, Guillaume Assié, Chiara Villa, James L Mills, Jacques Drouin, and Constantine A Stratakis
The CABLES1 cell cycle regulator participates in the adrenal–pituitary negative feedback, and its expression is reduced in corticotropinomas, pituitary tumors with a largely unexplained genetic basis. We investigated the presence of CABLES1 mutations/copy number variations (CNVs) and their associated clinical, histopathological and molecular features in patients with Cushing’s disease (CD). Samples from 146 pediatric (118 germline DNA only/28 germline and tumor DNA) and 35 adult (tumor DNA) CD patients were screened for CABLES1 mutations. CNVs were assessed in 116 pediatric CD patients (87 germline DNA only/29 germline and tumor DNA). Four potentially pathogenic missense variants in CABLES1 were identified, two in young adults (c.532G > A, p.E178K and c.718C > T, p.L240F) and two in children (c.935G > A, p.G312D and c.1388A > G, and p.D463G) with CD; no CNVs were found. The four variants affected residues within or close to the predicted cyclin-dependent kinase-3 (CDK3)-binding region of the CABLES1 protein and impaired its ability to block cell growth in a mouse corticotropinoma cell line (AtT20/D16v-F2). The four patients had macroadenomas. We provide evidence for a role of CABLES1 as a novel pituitary tumor-predisposing gene. Its function might link two of the main molecular mechanisms altered in corticotropinomas: the cyclin-dependent kinase/cyclin group of cell cycle regulators and the epidermal growth factor receptor signaling pathway. Further studies are needed to assess the prevalence of CABLES1 mutations among patients with other types of pituitary adenomas and to elucidate the pituitary-specific functions of this gene.
Dorota Dworakowska and Ashley B Grossman
Tuberous sclerosis complex (TSC) is an autosomal dominant multisystem disorder characterised by the development of multiple hamartomas in numerous organs. It is caused by mutations of two tumour suppressor genes, TSC1 on chromosome 9q34 and TSC2 on chromosome 16p13.3, which encode for hamartin and tuberin respectively. The interaction between these two proteins, the tuberin–hamartin complex, has been shown to be critical to multiple intracellular signalling pathways, especially those controlling cell growth and proliferation. TSC may affect skin, central nervous system, kidneys, heart, eyes, blood vessels, lung, bone and gastrointestinal tract. Small series and case reports have documented that in tuberous sclerosis patients many endocrine system alterations might occur, affecting the function of the pituitary, parathyroid and other neuroendocrine tissue. There have been scattered reports of the involvement of such tissue in the pathological process of TSC, but no systematic review as to whether this is a true association. We have therefore systematically assessed all available published literature in this area. We conclude that there may be an association with pituitary and parathyroid tumours, and two recent descriptions of Cushing's disease are especially intriguing. However, the evidence seems more firm in the case of islet cell tumours, particularly insulinomas. As these latter may cause changes in mental state that may be confused with the cerebral manifestations of TSC per se, it is particularly important for physicians working with these patients to be aware of the putative and indeed likely association.
Pushpa Patel, Rowan Hardy, Vaiyapuri Sumathi, Gillian Bartle, Lars-Gunnar Kindblom, Robert Grimer, Iwona Bujalska, Paul M Stewart, Elizabeth Rabbitt, Neil J L Gittoes, and Mark S Cooper
Osteosarcoma (OS) is a primary malignant tumour of bone occurring predominantly in children and young adults. Despite chemotherapy, relapse is common and mortality remains high. Non-transformed osteoblasts are highly sensitive to glucocorticoids, which reduce proliferation and induce apoptosis. Previously, we observed that OS cells, but not normal osteoblasts, express 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2). This enzyme inactivates cortisol (active) to cortisone (inactive) and expression of 11β-HSD2 renders OS cells resistant to glucocorticoids. By contrast, the related enzyme 11β-HSD1 converts cortisone to cortisol and reduces OS cell proliferation in vitro. Some synthetic glucocorticoids (e.g. dehydrodexamethasone (DHD), inactive counterpart of dexamethasone (DEX)) have been reported to be activated by 11β-HSD2. We therefore investigated expression and enzymatic activity of 11β-HSD isozymes in human OS tissue, determined whether 11β-HSD expression has prognostic value in the response to therapy, and evaluated the potential use of synthetic glucocorticoids to selectively target OS cells. OS samples expressed both 11β-HSD1 and 11β-HSD2. 11β-HSD1 expression in pretreatment biopsy specimens positively correlated with primary tumour size. Expression and activity of 11β-HSD1 in post-treatment biopsies were unrelated to the degree of tumour necrosis following chemotherapy. However, high 11β-HSD2 expression in post-treatment biopsies correlated with a poor response to therapy. OS cells that expressed 11β-HSD2 inactivated endogenous glucocorticoids; but these cells were also able to generate DEX from DHD. These results suggest that OS treatment response is related to 11β-HSD2 enzyme expression. Furthermore, OS cells expressing this enzyme could be targeted by treatment with synthetic glucocorticoids that are selectively reactivated by the enzyme.