Gene expression profiling of childhood adrenocortical tumors

Improvement of variables interpretability in kernel PCA

BACKGROUND

Kernel methods have been proven to be a powerful tool for the integration and analysis of high-throughput technologies generated data. Kernels offer a nonlinear version of any linear algorithm solely based on dot products. The kernelized version of principal component analysis is a valid nonlinear alternative to tackle the nonlinearity of biological sample spaces. This paper proposes a novel methodology to obtain a data-driven feature importance based on the kernel PCA representation of the data.

RESULTS

The proposed method, kernel PCA Interpretable Gradient (KPCA-IG), provides a data-driven feature importance that is computationally fast and based solely on linear algebra calculations. It has been compared with existing methods on three benchmark datasets. The accuracy obtained using KPCA-IG selected features is equal to or greater than the other methods' average. Also, the computational complexity required demonstrates the high efficiency of the method. An exhaustive literature search has been conducted on the selected genes from a publicly available Hepatocellular carcinoma dataset to validate the retained features from a biological point of view. The results once again remark on the appropriateness of the computed ranking.

CONCLUSIONS

The black-box nature of kernel PCA needs new methods to interpret the original features. Our proposed methodology KPCA-IG proved to be a valid alternative to select influential variables in high-dimensional high-throughput datasets, potentially unravelling new biological and medical biomarkers.

Steroidogenic Factor 1, a Goldilocks Transcription Factor from Adrenocortical Organogenesis to Malignancy

Steroidogenic factor-1 (SF-1, also termed Ad4BP; NR5A1 in the official nomenclature) is a nuclear receptor transcription factor that plays a crucial role in the regulation of adrenal and gonadal development, function and maintenance. In addition to its classical role in regulating the expression of P450 steroid hydroxylases and other steroidogenic genes, involvement in other key processes such as cell survival/proliferation and cytoskeleton dynamics have also been highlighted for SF-1. SF-1 has a restricted pattern of expression, being expressed along the hypothalamic-pituitary axis and in steroidogenic organs since the time of their establishment. Reduced SF-1 expression affects proper gonadal and adrenal organogenesis and function. On the other hand, SF-1 overexpression is found in adrenocortical carcinoma and represents a prognostic marker for patients' survival. This review is focused on the current knowledge about SF-1 and the crucial importance of its dosage for adrenal gland development and function, from its involvement in adrenal cortex formation to tumorigenesis. Overall, data converge towards SF-1 being a key player in the complex network of transcriptional regulation within the adrenal gland in a dosage-dependent manner.

FGF/FGFR signaling in adrenocortical development and tumorigenesis: novel potential therapeutic targets in adrenocortical carcinoma

FGF/FGFR signaling regulates embryogenesis, angiogenesis, tissue homeostasis and wound repair by modulating proliferation, differentiation, survival, migration and metabolism of target cells. Understandably, compelling evidence for deregulated FGF signaling in the development and progression of different types of tumors continue to emerge and FGFR inhibitors arise as potential targeted therapeutic agents, particularly in tumors harboring aberrant FGFR signaling. There is first evidence of a dual role of the FGF/FGFR system in both organogenesis and tumorigenesis, of which this review aims to provide an overview. FGF-1 and FGF-2 are expressed in the adrenal cortex and are the most powerful mitogens for adrenocortical cells. Physiologically, they are involved in development and maintenance of the adrenal gland and bind to a family of four tyrosine kinase receptors, among which FGFR1 and FGFR4 are the most strongly expressed in the adrenal cortex. The repeatedly proven overexpression of these two FGFRs also in adrenocortical cancer is thus likely a sign of their participation in proliferation and vascularization, though the exact downstream mechanisms are not yet elucidated. Thus, FGFRs potentially offer novel therapeutic targets also for adrenocortical carcinoma, a type of cancer resistant to conventional antimitotic agents.

Identification of potential core genes and miRNAs in pediatric ACC via bioinformatics analysis

Pediatric adrenocortical carcinomas (ACC) are rare aggressive neoplasms with heterogeneous prognosis, and often produce a most lethal malignant tumor, whereas its aetiology is still unclear. The aim of the present study was to identify the factors responsible for the development of pediatric ACC, a better understanding of the disease, and investigate new molecular biomarkers and therapeutic targets. To identify the key genes and miRNAs linked to pediatric ACC, as well as their potential molecular mechanisms, the GSEGSE75415 and GSE169253 microarray datasets were analyzed. A total of 329 differentially produced genes (DEGs) and 187 differentially produced miRNAs (DEMs) were obtained after analyzing the GSEGSE75415 and GSE169253 datasets, respectively. Next, 3,359 genes were obtained by overlapping the target mRNAs of DEMs. Following protein-protein interaction network and Gene Ontology analysis, the ten nodes with the highest degrees were screened as hub genes. Among them, the highly expressed hub genes, MAPK1 and EP300, were associated with a worse overall survival. Additionally, hsa-miR-376, hsa-miR-148, hsa-miR-139, and hsa-miR-1305 were strongly associated with poorer survival. We proposed that the hub genes (MAPK1, EP300, hsa-miR-376, hsa-miR-148, hsa-miR-139, and hsa-miR-1305) may have a definite impact on cellular proliferation and migration in adrenocortical tumors. The roles of these hub genes in adrenocortical tumors may provide novel insight to improve the diagnosis and treatment of patients with pediatric ACC.

Identification of Four Novel Prognostic Biomarkers and Construction of Two Nomograms in Adrenocortical Carcinoma: A Multi-Omics Data Study via Bioinformatics and Machine Learning Methods

Background: Adrenocortical carcinoma (ACC) is an orphan tumor which has poor prognoses. Therefore, it is of urgent need for us to find candidate prognostic biomarkers and provide clinicians with an accurate method for survival prediction of ACC via bioinformatics and machine learning methods.

Methods: Eight different methods including differentially expressed gene (DEG) analysis, weighted correlation network analysis (WGCNA), protein-protein interaction (PPI) network construction, survival analysis, expression level comparison, receiver operating characteristic (ROC) analysis, and decision curve analysis (DCA) were used to identify potential prognostic biomarkers for ACC via seven independent datasets. Linear discriminant analysis (LDA), K-nearest neighbor (KNN), support vector machine (SVM), and time-dependent ROC were performed to further identify meaningful prognostic biomarkers (MPBs). Cox regression analyses were performed to screen factors for nomogram construction.

Results: We identified nine hub genes correlated to prognosis of patients with ACC. Furthermore, four MPBs (ASPM, BIRC5, CCNB2, and CDK1) with high accuracy of survival prediction were screened out, which were enriched in the cell cycle. We also found that mutations and copy number variants of these MPBs were associated with overall survival (OS) of ACC patients. Moreover, MPB expressions were associated with immune infiltration level. Two nomograms [OS-nomogram and disease-free survival (DFS)-nomogram] were established, which could provide clinicians with an accurate, quick, and visualized method for survival prediction.

Conclusion: Four novel MPBs were identified and two nomograms were constructed, which might constitute a breakthrough in treatment and prognosis prediction of patients with ACC.

Distinct Murine Pancreatic Transcriptomic Signatures during Chronic Pancreatitis Recovery

We have previously demonstrated that the pancreas can recover from chronic pancreatitis (CP) lesions in the cerulein-induced mouse model. To explore how pancreatic recovery is achieved at the molecular level, we used RNA-sequencing (seq) and profiled transcriptomes during CP transition to recovery. CP was induced by intraperitoneally injecting cerulein in C57BL/6 mice. Time-matched controls (CON) were given normal saline. Pancreata were harvested from mice 4 days after the final injections (designated as CP and CON) or 4 weeks after the final injections (designated as CP recovery (CPR) and control recovery (CONR)). Pancreatic RNAs were extracted for RNA-seq and quantitative (q) PCR validation. Using RNA-seq, we identified a total of 3,600 differentially expressed genes (DEGs) in CP versus CON and 166 DEGs in CPR versus CONR. There are 132 DEGs overlapped between CP and CPR and 34 DEGs unique to CPR. A number of selected pancreatic fibrosis-relevant DEGs were validated by qPCR. The top 20 gene sets enriched from DEGs shared between CP and CPR are relevant to extracellular matrix and cancer biology, whereas the top 10 gene sets enriched from DEGs specific to CPR are pertinent to DNA methylation and specific signaling pathways. In conclusion, we identified a distinct set of DEGs in association with extracellular matrix and cancer cell activities to contrast CP and CPR. Once during ongoing CP recovery, DEGs relevant to DNA methylation and specific signaling pathways were induced to express. The DEGs shared between CP and CPR and the DEGs specific to CPR may serve as the unique transcriptomic signatures and biomarkers for determining CP recovery and monitoring potential therapeutic responses at the molecular level to reflect pancreatic histological resolution.

New Prognostic Indicators in Pediatric Adrenal Tumors: Neuroblastoma and Adrenal Cortical Tumors, Can We Predict When These Will Behave Badly?

Pediatric adrenal tumors are unique entities with specific diagnostic, prognostic, and therapeutic challenges. The adrenal medulla gives rise to peripheral neuroblastic tumors (pNTs), pathologically defined by their architecture, stromal content, degree of differentiation, and mitotic-karyorrhectic index. Successful risk stratification of pNTs uses patient age, stage, tumor histology, and molecular/genetic aberrations. The adrenal cortex gives rise to adrenocortical tumors (ACTs), which present diagnostic and prognostic challenges. Histologic features that signify poor prognosis in adults can be meaningless in children, who have superior outcomes. The key clinical, pathologic, and molecular findings of pediatric ACTs have yet to be completely identified.

Pathway Analysis of Renal Cell Carcinoma Genome-Wide Association Studies Identifies Novel Associations

BACKGROUND

Much of the heritable risk of renal cell carcinoma (RCC) associated with common genetic variation is unexplained. New analytic approaches have been developed to increase the discovery of risk variants in genome-wide association studies (GWAS), including multi-locus testing through pathway analysis.

METHODS

We conducted a pathway analysis using GWAS summary data from six previous scans (10,784 cases and 20,406 controls) and evaluated 3,678 pathways and gene sets drawn from the Molecular Signatures Database. To replicate findings, we analyzed GWAS summary data from the UK Biobank (903 cases and 451,361 controls) and the Genetic Epidemiology Research on Adult Health and Aging cohort (317 cases and 50,511 controls).

RESULTS

We identified 14 pathways/gene sets associated with RCC in both the discovery (P < 1.36 × 10-5, the Bonferroni correction threshold) and replication (P < 0.05) sets, 10 of which include components of the PI3K/AKT pathway. In tests across 2,035 genes in these pathways, associations (Bonferroni corrected P < 2.46 × 10-5 in discovery and replication sets combined) were observed for CASP9, TIPIN, and CDKN2C. The strongest SNP signal was for rs12124078 (P Discovery = 2.6 × 10-5; P Replication = 1.5 × 10-4; P Combined = 6.9 × 10-8), a CASP9 expression quantitative trait locus.

CONCLUSIONS

Our pathway analysis implicates genetic variation within the PI3K/AKT pathway as a source of RCC heritability and identifies several promising novel susceptibility genes, including CASP9, which warrant further investigation.

IMPACT

Our findings illustrate the value of pathway analysis as a complementary approach to analyzing GWAS data.

Pediatric adrenocortical tumours

Childhood adrenocortical tumors (ACTs) are rare, representing ∼0.2% of all pediatric malignancies and having an incidence of 0.2-0.3 new cases per million per year in the United States, but incidences are remarkably higher in Southern Brazil. At diagnosis, most children show signs and symptoms of virilization, Cushing syndrome, or both. Less than 10% of patients with ACT exhibit no endocrine syndrome at presentation, although some show abnormal concentrations of adrenal cortex hormones. Pediatric ACT is commonly associated with constitutional genetic and/or epigenetic alterations, represented by germline TP53 mutations or chromosome 11p abnormalities. Complete tumor resection is required to achieve cure. The role of chemotherapy is not established, although definitive responses to several anticancer drugs are documented. For patients undergoing complete tumor resection, favorable prognostic factors include young age, small tumor size, virilization, and adenoma histology. Prospective studies are necessary to further elucidate the pathogenesis of ACT and improve patient outcomes.

Stathmin 1 is highly expressed and associated with survival outcome in malignant adrenocortical tumours

Adrenocortical carcinoma (ACC) is an aggressive endocrine cancer with few molecular predictors of malignancy and survival, especially in paediatric patients. Stathmin 1 (STMN1) regulates microtubule dynamics and has been involved in the malignant phenotype of cancer cells. Recently, it was reported that STMN1 is highly expressed in ACC patients, and STMN1 silencing reduces the clonogenicity and migration of ACC cell lines. However, the prognostic significance of STMN1 and its therapeutic potential remain undefined in ACC. In the present study, STMN1 mRNA levels were significantly higher (p < 0.05) in ACC patients, especially in an advanced stage, and correlated with BUB1B and PINK1 expression, the prognostic-related genes in ACC. In paediatric tumours, high STMN1 expression was observed in both adrenocortical carcinoma and adrenocortical adenoma patients. Among the adult malignant tumours, STMN1 level was an independent predictor of survival outcomes (overall survival: hazard ratio = 6.08, p = 0.002; disease-free survival: hazard ratio = 4.65, p < 0.0001). Paclitaxel, a microtubule-stabilizing drug, reduces the activation of STMN1 and significantly decreases cell migration and invasion in ACC cell lines and ACC cells from secondary cell culture (all p < 0.0001). In summary, STMN1 expression may be of great value to clinical and pathological findings in therapeutic trials and deserves future studies in ACC.

Pathobiology and genetics of adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare malignancy with an incidence worldwide of 0.7-2.0 cases/million/year. Initial staging is the most important factor in determining prognosis. If diagnosed early, complete surgical resection +/- adjuvant treatment can lead to 5-year survival of up to 80%. However, often it is diagnosed late and in advanced disease, 5-year survival is <15% with a high recurrence rate even after radical surgery. The mainstay of adjuvant treatment is with the drug mitotane. Mitotane has a specific cytotoxic effect on steroidogenic cells of the adrenal cortex, but despite this, progression through treatment is common. Developments in genetic analysis in the form of next-generation sequencing, aided by bioinformatics, have enabled high-throughput molecular characterisation of these tumours. This, in addition to a better appreciation of the processes of physiological, homeostatic self-renewal of the adrenal cortex, has furthered our understanding of the pathogenesis of this malignancy. In this review, we have detailed the pathobiology and genetic alterations in adrenocortical carcinoma by integrating current understanding of homeostasis and self-renewal in the normal adrenal cortex with molecular profiling of tumours from recent genetic analyses. Improved understanding of the mechanisms involved in self-renewal and stem cell hierarchy in normal human adrenal cortices, together with the identification of cell populations likely to be co-opted by oncogenic mutations, will enable further progress in the definition of the molecular pathways involved in the pathogenesis of ACC. The combination of these advances eventually will lead to the development of novel, effective and personalised strategies to eradicate molecularly annotated ACCs.

Identification of Seven Aberrantly Methylated and Expressed Genes in Adrenocortical Carcinoma

Background: Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with an unfavorable prognosis and limited treatment options. Nevertheless, no clinically applicable molecular markers have been identified for the progression of ACCs. DNA methylation alterations were found to contribute to the development of ACC in recent decades. Material and Methods: The aims of the current study was to identify the abnormally methylated differentially expressed genes (DEGs) in ACCs, and to elucidate the mechanistic basis for these changes. Analyses were conducted on gene expression and gene methylation profile datasets to identify the aberrantly methylated DEGs. The DAVID software was used to conduct the analyses of functional enrichment on screened genes. Finally, expression was validated, and the relationship between abnormally methylated DEGs and clinical features was determined via the Oncomine database and The Cancer Genome Atlas (TCGA). To further verify the altered expression and methylation status of our identified genes we also validated these changes at the tissue and cellular levels. Results: We screened and identified 92 differentially expressed genes and 802 abnormally methylated genes. Furthermore, seven aberrantly methylated and dysregulated genes were identified and validated, along with a number of functional enriched pathways. Among these seven genes, the expression or methylation status is significantly correlated with different pathological stages and overall rates of survival. In validation, the expression of seven genes were significantly altered and five genes were hypermethylated in ACC. Conclusions: Our study identified abnormally methylated DEGs and potentially affected pathways in ACCs, from which we could begin to understand the basic molecular mechanisms of these alterations. Moreover, these abnormally methylated genes might serve as therapeutic targets and biomarkers to allow ACC patients to be more precisely diagnosed and effectively treated.

Human Adrenal Cortex: Epigenetics and Postnatal Functional Zonation

The human adrenal cortex, involved in adaptive responses to stress, fluid homeostasis, and secondary sexual characteristics, arises from a tightly regulated development of a zone and cell type-specific secretory pattern. However, the molecular mechanisms governing adrenal zonation, particularly postnatal zona reticularis development, which produce adrenal androgens in a lifetime-specific manner, remain poorly understood. Epigenetic events, including DNA and histone modifications as well as regulation by noncoding RNAs, are crucial in establishing or maintaining the expression pattern of specific genes and thus contribute to the stability of a specific differentiation state. Emerging evidence points to epigenetics as another regulatory layer that could contribute to establishing the adrenal zone-specific pattern of enzyme expression. Here, we outline the developmental milestones of the human adrenal cortex, focusing on current advances and understanding of epigenetic regulation of postnatal functional zonation. Numerous questions remain to be addressed emphasizing the need for additional investigations to elucidate the role of epigenetics in the human adrenal gland. Ultimately, improved understanding of the epigenetic factors involved in adrenal development and function could lead to novel therapeutic interventions.

MECHANISMS OF ENDOCRINOLOGY: Cell cycle regulation in adrenocortical carcinoma

Adrenocortical carcinomas (ACCs) are rather rare endocrine tumors that often have a poor prognosis. The reduced survival rate associated with these tumors is due to their aggressive biological behavior, combined with the scarcity of effective treatment options that are currently available. The recent identification of the genomic alterations present in ACC have provided further molecular mechanisms to develop consistent strategies for the diagnosis, prevention of progression and treatment of advanced ACCs. Taken together, molecular and genomic advances could be leading the way to develop personalized medicine in ACCs similarly to similar developments in lung or breast cancers. In this review, we focused our attention to systematically compile and summarize the alterations in the cell cycle regulation that were described so far in ACC as they are known to play a crucial role in cell differentiation and growth. We have divided the analysis according to the major transition phases of the cell cycle, G1 to S and G2 to M. We have analyzed the most extensively studied checkpoints: the p53/Rb1 pathway, CDC2/cyclin B and topoisomerases (TOPs). We reached the conclusion that the most important alterations having a potential application in clinical practice are the ones related to p53/Rb1 and TOP 2. We also present a brief description of on-going clinical trials based on molecular alterations in ACC. The drugs have targeted the insulin-like growth factor receptor 1, TOP 2, polo-like kinase1, cyclin-dependent kinase inhibitors, p53 reactivation and CDC25.

The challenge of developmental therapeutics for adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare disease with an estimated incidence of only 0.7 new cases per million per year. Approximately 30-70% of the patients present with advanced disease with very poor prognosis and without effective therapeutic options. In the recent years, unprecedented progresses in cancer biology and genomics have fostered the development of numerous targeted therapies for various malignancies. Immunotherapy has also transformed the treatment landscape of malignancies such as melanoma, among others. However, these advances have not brought meaningful benefits for patients with ACC. Extensive genomic analyses of ACC have revealed numerous signal transduction pathway aberrations (e.g., insulin growth factor receptor and Wnt/β-catenin pathways) that play a central role in pathophysiology. These molecular alterations have been explored as potential therapeutic targets for drug development. This manuscript summarizes recent discoveries in ACC biology, reviews the results of early clinical studies with targeted therapies, and provides the rationale for emerging treatment strategies such as immunotherapy.

The next step: mechanisms driving adrenocortical carcinoma metastasis

Endocrine tumors have the peculiarity to become clinically evident not only due to symptoms related to space occupation by the growing lesion, similarly to most other tumors, but also, and most often, because of their specific hormonal secretion, which significantly contributes to their pathological burden. Malignant endocrine tumors, in addition, have the ability to produce distant metastases. Here, we critically review the current knowledge about mechanisms and biomarkers characterizing the metastatic process in adrenocortical carcinoma (ACC), a rare endocrine malignancy with a high risk of relapse and metastatization even when the primary tumor is diagnosed and surgically removed at an early stage. We highlight perspectives of future research in the domain and possible new therapeutic avenues based on targeting factors having an important role in the metastatic process of ACC.

TCF21/POD-1, a Transcritional Regulator of SF-1/NR5A1, as a Potential Prognosis Marker in Adult and Pediatric Adrenocortical Tumors

With recent progress in understanding the pathogenesis of adrenocortical tumors (ACTs), identification of molecular markers to predict their prognosis has become possible. Transcription factor 21 (TCF21)/podocyte-expressed 1 (POD1) is a transcriptional regulatory protein expressed in mesenchymal cells at sites of epithelial-mesenchymal transition during the development of different systems. Adult carcinomas express less TCF21 than adenomas, in addition, the KEGG pathway analysis has shown that BUB1B, among others genes, is negatively correlated with TCF21 expression. The difference between BUB1B and PTEN-induced putative kinase 1 (PINK1) expression has been described previously to be associated with survival in adult but not in pediatric carcinomas. Here, we analyzed the gene expression of TCF21, BUB1B, PINK1, and NR5A1 in adult and pediatric ACTs. We found a negative correlation between the relative expression levels of TCF21 and BUB1B in adult ACTs, but the relative expression levels of TCF21, BUB1B, PINK1, and NR5A1 were similar in childhood ACTs. In addition, we propose using the subtracted expression levels of the TCF21/POD-1 genes as a predictor of overall survival (OS) in adult carcinomas and TCF21-NR5A1 as a predictor of malignancy for pediatric tumors in patients aged <5 years. These results require further validation in different cohorts of both adult and pediatric samples. Finally, we observed that the OS for patients aged <5 years was markedly favorable compared with that for patients >5 years as well as adult patients with carcinoma. In summary, we propose TCF21/POD-1 as a new prognostic marker in adult and pediatric ACTs.

Common module analysis reveals prospective targets and mechanisms of pediatric adrenocortical adenoma and carcinoma

Pediatric adrenocortical carcinoma and adrenocortical adenoma are two rare diseases affecting children. Molecular analyses were performed to identify commonalities in gene expression between the diseases. Differentially expressed genes were identified for the pediatric adrenocortical adenoma and carcinoma tissues, as compared with normal tissues, using the expression dataset. Protein-protein interaction (PPI) networks were constructed for adenoma and carcinoma disease models, and common modules among the diseases were identified. A total of two common modules with 14 nodes and 20 nodes were revealed among the adenoma and carcinoma networks, respectively. Genes of the common modules were also identified to be the common hub genes of the disease models. Enrichment of the genes of the common modules suggested associations with steroid biosynthesis, the proteasome, cell cycle and metabolic pathways. Modularity, topological and functional analysis of the PPI networks revealed common modules among pediatric adenoma and carcinoma disease models, which provided insight into the underlying disease mechanisms and suggesting prospective targets for future study.

Identification of Clinical and Biologic Correlates Associated With Outcome in Children With Adrenocortical Tumors Without Germline TP53 Mutations: A St Jude Adrenocortical Tumor Registry and Children's Oncology Group Study

Purpose The clinical features, pathogenesis, and outcomes in children with adrenocortical tumors (ACTs) without germline TP53 mutations have not been systematically studied. Herein, we describe these correlates and analyze their association with outcome. Patients and Methods Genomic DNA was analyzed for TP53, CTNNB1, CDKN1C, ATRX, and chromosome 11p15 abnormalities. β-catenin expression and Ki-67 labeling index (LI) were evaluated by immunostaining. Primary end points were progression-free (PFS) and overall survival. Results Median age of 42 girls and 18 boys was 3.3 years (range, 0.25 to 21.7 years). Complete resection (stages I and II) was achieved in 32 patients, and 28 patients had stage III or IV disease. Constitutional abnormalities of chromosome 11p15 occurred in nine of 40 patients, with six patients not showing phenotype of Beckwith-Wiedemann syndrome. Three-year PFS and overall survival for all patients were 71.4% and 80.5%, respectively. In single-predictor Cox regression analysis, age, disease stage, tumor weight, somatic TP53 mutations, and Ki-67 LI were associated with prognosis. Ki-67 LI and age remained significantly associated with PFS after adjusting for stage and tumor weight. Three-year PFS for 27 patients with Ki-67 LI ≥ 15% was 48.5% compared with 96.2% for 29 patients with Ki-67 LI < 15% (log-rank P = .002), and the rate of relapse increased by 24% with each 1-year increase in age at diagnosis (hazard ratio, 1.24; P = .0057). Conclusion Clinicopathologic features and outcomes of children with ACTs without germline TP53 mutations overlapped those reported for children with germline TP53 mutations. Our findings highlight the central role of genetic or epigenetic alterations on chromosome 11p15 in pediatric ACTs. Ki-67 LI is a strong prognostic indicator and should be investigated to improve the histologic classification of pediatric ACTs.

Androgen production in pediatric adrenocortical tumors may occur via both the classic and/or the alternative backdoor pathway

Children with adrenocortical tumors (ACTs) often present with virilization due to high tumoral androgen production, with dihydrotestosterone (DHT) as most potent androgen. Recent work revealed two pathways for DHT biosynthesis, the classic and the backdoor pathway. Usage of alternate routes for DHT production has been reported in castration-resistant prostate cancer, CAH and PCOS. To assess whether the backdoor pathway may contribute to the virilization of pediatric ACTs, we investigated seven children suffering from androgen producing tumors using steroid profiling and immunohistochemical expression studies. All cases produced large amounts of androgens of the classic and/or backdoor pathway. Variable expression of steroid enzymes was observed in carcinomas and adenomas. We found no discriminative pattern. This suggests that enhanced androgen production in pediatric ACTs is the result of deregulated steroidogenesis through multiple steroid pathways. Thus future treatments of ACTs targeting androgen overproduction should consider these novel steroid production pathways.

GLUT1 expression in pediatric adrenocortical tumors: a promising candidate to predict clinical behavior

Background

Discrimination between benign and malignant tumors is a challenging process in pediatric adrenocortical tumors. New insights in the metabolic profile of pediatric adrenocortical tumors may contribute to this distinction, predict prognosis, as well as identify new molecular targets for therapy. The aim of this work is to characterize the expression of the metabolism-related proteins MCT1, MCT2, MCT4, CD147, CD44, GLUT1 and CAIX in a series of pediatric adrenocortical tumors.

Methods

A total of 50 pediatric patients presenting adrenocortical tumors, including 41 clinically benign and 9 clinically malignant tumors, were included. Protein expression was evaluated using immunohistochemistry in samples arranged in tissue microarrays.

Results

The immunohistochemical analysis showed a significant increase in plasma membrane expression of GLUT1 in malignant lesions, when compared to benign lesions (p=0.004), being the expression of this protein associated with shorter overall and disease-free survival (p=0.004 and p=0.001, respectively). Although significant differences were not observed for proteins other than GLUT1, MCT1, MCT4 and CD147 were highly expressed in pediatric adrenocortical neoplasias (around 90%).

Conclusion

GLUT1 expression was differentially expressed in pediatric adrenocortical tumors, with higher expression in clinically malignant tumors, and associated with shorter survival, suggesting a metabolic remodeling towards a hyperglycolytic phenotype in this malignancy.

Molecular targeted therapies in adrenal, pituitary and parathyroid malignancies

Tumourigenesis is a relatively common event in endocrine tissues. Currently, specific guidelines have been developed for common malignant endocrine tumours, which also incorporate advances in molecular targeted therapies (MTT), as in thyroid cancer and in gastrointestinal neuroendocrine malignancies. However, there is little information regarding the role and efficacy of MTT in the relatively rare malignant endocrine tumours mainly involving the adrenal medulla, adrenal cortex, pituitary, and parathyroid glands. Due to the rarity of these tumours and the lack of prospective studies, current guidelines are mostly based on retrospective data derived from surgical, locoregional and ablative therapies, and studies with systemic chemotherapy. In addition, in many of these malignancies the prognosis remains poor with individual patients responding differently to currently available treatments, necessitating the development of new personalised therapeutic strategies. Recently, major advances in the molecular understanding of endocrine tumours based on genomic, epigenomic, and transcriptome analysis have emerged, resulting in new insights into their pathogenesis and molecular pathology. This in turn has led to the use of novel MTTs in increasing numbers of patients. In this review, we aim to present currently existing and evolving data using MTT in the treatment of adrenal, pituitary and malignant parathyroid tumours, and explore the current utility and effectiveness of such therapies and their future evolution.

Cell signaling pathways in the adrenal cortex: Links to stem/progenitor biology and neoplasia

The adrenal cortex is a dynamic tissue responsible for the synthesis of steroid hormones, including mineralocorticoids, glucocorticoids, and androgens in humans. Advances have been made in understanding the role of adrenocortical stem/progenitor cell populations in cortex homeostasis and self-renewal. Recently, large molecular profiling studies of adrenocortical carcinoma (ACC) have given insights into proteins and signaling pathways involved in normal tissue homeostasis that become dysregulated in cancer. These data provide an impetus to examine the cellular pathways implicated in adrenocortical disease and study connections, or lack thereof, between adrenal homeostasis and tumorigenesis, with a particular focus on stem and progenitor cell pathways. In this review, we discuss evidence for stem/progenitor cells in the adrenal cortex, proteins and signaling pathways that may regulate these cells, and the role these proteins play in pathologic and neoplastic conditions. In turn, we also examine common perturbations in adrenocortical tumors (ACT) and how these proteins and pathways may be involved in adrenal homeostasis.

Adrenocortical neoplasms in adulthood and childhood: distinct presentation. Review of the clinical, pathological and imaging characteristics

Adrenocortical tumors (ACT) in adulthood and childhood vary in clinical, histopathological, molecular, prognostic, and imaging aspects. ACT are relatively common in adults, as adenomas are often found incidentally on imaging. ACT are rare in children, though they have a significantly higher prevalence in the south and southeast regions of Brazil. In clinical manifestation, adults with ACT present more frequently with glucocorticoid overproduction (Cushing syndrome), mineralocorticoid syndromes (Conn syndrome), or the excess of androgens in women. Subclinical tumors are frequently diagnosed late, associated with compression symptoms of abdominal mass. In children, the usual presentation is the virilizing syndrome or virilizing association and hypercortisolism. Histopathological grading and ACT classification in malignant and benign lesions are different for adults and children. In adults, the described criteria are the Hough, Weiss, modified Weiss, and Van Slooten. These scores are not valid for children; there are other criteria, such as proposed by Wieneke and colleagues. In molecular terms, there is also a difference related to genetic alterations found in these two populations. This review discusses the imaging findings of ACT, aiming to characterize the present differences between ACT found in adults and children. We listed several differences between magnetic resonance imaging (MRI), computed tomography (CT), and positron emission tomography-computed (PET-CT) and also performed a literature review, which focuses on studied age groups of published articles in the last 10 years regarding cortical neoplasm and imaging techniques. Published studies on ACT imaging in children are rare. It is important to stress that the majority of publications related to the differentiation of malignant and benign tumors are based almost exclusively on studies in adults. A minority of articles, however, studied adults and children together, which may not be appropriate.

DNA methylation is not involved in specific down-regulation of HSD3B2, NR4A1 and RARB genes in androgen-secreting cells of human adrenal cortex

We hypothesized that DNA methylation is involved in human adrenal functional zonation. mRNAs expression and methylation pattern of RARB, NR4A1 and HSD3B2 genes in human adrenal tissues (HAT) and in pediatric virilizing adrenocortical tumors (VAT) were analyzed. For analysis of the results samples were divided into 3 age groups according to FeZ involution, pre and post-adrenarche ages. In all HAT, similar RARB mRNA was found including microdissected zona reticularis (ZR) and zona fasciculata, but HSD3B2 and NR4A1 mRNAs were lower in ZR (p < 0.05). NR4A1 and RARB promoters remained unmethylated in HAT and VAT. No adrenal zone-specific differences in NR4A1 methylation were observed. In summary, RARB was not associated with ZR-specific downregulation of HSD3B2 in postnatal human adrenocotical zonation. DNA methylation would not be involved in NR4A1 adrenocortical cell-type specific downregulation. Lack of CpG islands in HSD3B2 suggested that HSD3B2 ZR-specific downregulation would not be directly mediated by DNA methylation.

Genetics of adrenocortical tumours

The recently available genomic sequencing techniques have led to breakthroughs in understanding of the underlying genetic mechanisms in adrenocortical tumours. Disease-causing mutations have been described for aldosterone-producing adenomas, cortisol-producing adenomas and adrenocortical carcinomas. Further, knowledge gained from transcriptome analyses and methylation arrays has provided new insights into the development of these tumours. Elucidation of the genomic landscape of adrenocortical tumours and improved techniques may in the future be useful for early diagnosis through the detection of mutated DNA in the circulation. Moreover, compounds that bind specifically to altered proteins may be used as screening targets or therapeutic agents. Regulation of cortisol release by interaction with an altered subunit in adenylate cyclase may be more complex, but may provide a new option for regulating steroid release. Information about derangements in adrenocortical carcinoma is already helpful for determining patient prognosis. With further knowledge, we may be able to identify novel biomarkers that effectively and noninvasively help in differentiating between benign and malignant disease. It is clear that the next few years will provide much novel information that hopefully will aid in the treatment of patients with adrenocortical tumours.

Network analysis reveals potential markers for pediatric adrenocortical carcinoma

Pediatric adrenocortical carcinoma (ACC) is a rare malignancy with a poor outcome. Molecular mechanisms of pediatric ACC oncogenesis and advancement are not well understood. Accurate and timely diagnosis of the disease requires identification of new markers for pediatric ACC. Differentially expressed genes (DEGs) were identified from the gene expression profile of pediatric ACC and obtained from Gene Expression Omnibus. Gene Ontology functional and pathway enrichment analysis was implemented to recognize the functions of DEGs. A protein–protein interaction (PPI) and gene–gene functional interaction (GGI) network of DEGs was constructed. Hub gene detection and enrichment analysis of functional modules were performed. Furthermore, a gene regulatory network incorporating DEGs–microRNAs–transcription factors was constructed and analyzed. A total of 431 DEGs including 228 upregulated and 203 downregulated DEGs were screened. These genes were largely involved in cell cycle, steroid biosynthesis, and p53 signaling pathways. Upregulated genes, CDK1, CCNB1, CDC20, and BUB1B, were identified as the common hubs of PPI and GGI networks. All the four common hub genes were also part of modules of the PPI network. Moreover, all the four genes were also present in the largest module of GGI network. A gene regulatory network consisting of 82 microRNAs and 100 transcription factors was also constructed. CDK1, CCNB1, CDC20, and BUB1B may serve as potential biomarker of pediatric ACC and as potential targets for therapeutic approach, although experimental studies are required to authenticate our findings.

Prognostic Significance of Major Histocompatibility Complex Class II Expression in Pediatric Adrenocortical Tumors: A St. Jude and Children's Oncology Group Study

PURPOSE

Histologic markers that differentiate benign and malignant pediatric adrenocortical tumors are lacking. Previous studies have implicated an association of MHC class II expression with adrenocortical tumor prognosis. Here, we determined the expression of MHC class II as well as the cell of origin of these immunologic markers in pediatric adrenocortical tumor. The impact of MHC class II gene expression on outcome was determined in a cohort of uniformly treated children with adrenocortical carcinomas.

EXPERIMENTAL DESIGN

We analyzed the expression of MHC class II and a selected cluster of differentiation genes in 63 pediatric adrenocortical tumors by Affymetrix Human U133 Plus 2.0 or HT HG-U133+PM gene chip analyses. Cells expressing MHC class II were identified by morphologic and immunohistochemical assays.

RESULTS

MHC class II expression was significantly greater in adrenocortical adenomas than in carcinomas (P = 4.8 ×10^-6) and was associated with a higher progression-free survival (PFS) estimate (P = 0.003). Specifically, HLA-DPA1 expression was most significantly associated with PFS after adjustment for tumor weight and stage. HLA-DPA1 was predominantly expressed by hematopoietic infiltrating cells and undetectable in tumor cells in 23 of 26 cases (88%).

CONCLUSIONS

MHC class II expression, which is produced by tumor-infiltrating immune cells, is an indicator of disease aggressiveness in pediatric adrenocortical tumor. Our results suggest that immune responses modulate adrenocortical tumorigenesis and may allow the refinement of risk stratification and treatment for this disease. Clin Cancer Res; 22(24); 6247-55. ©2016 AACR.

Novel targeted therapies in adrenocortical carcinoma

PURPOSE OF REVIEW

Adrenocortical carcinoma is a rare cancer, but one that carries a poor prognosis due to its aggressive nature and unresponsiveness to conventional chemotherapeutic strategies. Over the past 12 years, there has been renewed interest in developing new therapies for this cancer, including identifying key signaling nodes responsible for cell proliferation.

RECENT FINDINGS

Clinical trials of tyrosine kinase inhibitors as monotherapy have generally been disappointing, although the identification of exceptional responders may lead to the identification of targeted therapies that may produce responses in subsets of patients. Agents targeted to the Wnt signaling pathway, a known player in adrenal carcinogenesis, have been developed, although they have not yet been used specifically for adrenal cancer. There is current excitement about inhibitors of acetyl-coA cholesterol acetyl transferase 1, an enzyme required for intracellular cholesterol handling, although trials are still underway. Tools to target other proteins such as Steroidogenic Factor 1 and mechanistic target of rapamycin have been developed and are moving towards clinical application.

SUMMARY

Progress is being made in the fight against adrenocortical carcinoma with the identification of new therapeutic targets and new means by which to attack them. Continued improvement in the prognosis for patients with adrenal cancer is expected as this research continues.

IGF2 and IGF1R in pediatric adrenocortical tumors: roles in metastasis and steroidogenesis

Deregulation of the IGF system observed in human tumors indicates a role in malignant cell transformation and in tumor cell proliferation. Although overexpression of the IGF2 and IGF1R genes was described in adrenocortical tumors (ACTs), few studies reported their profiles in pediatric ACTs. In this study, the IGF2 and IGF1R expression was evaluated by RT-qPCR according to the patient's clinical/pathological features in 60 pediatric ACT samples, and IGF1R protein was investigated in 45 samples by immunohistochemistry (IHC). Whole transcriptome and functional assays were conducted after IGF1R inhibition with OSI-906 in NCI-H295A cell line. Significant IGF2 overexpression was found in tumor samples when compared with non-neoplastic samples (P<0.001), significantly higher levels of IGF1R in patients with relapse/metastasis (P=0.031) and moderate/strong IGF1R immunostaining in 62.2% of ACTs, but no other relationship with patient survival and clinical/pathological features was observed. OSI-906 treatment downregulated genes associated with MAPK activity, induced limited reduction of cell viability and increased the apoptosis rate. After 24h, the treatment also decreased the expression of genes related to the steroid biosynthetic process, the protein levels of the steroidogenic acute regulatory protein (STAR), and androgen secretion in cell medium, supporting the role of IGF1R in steroidogenesis of adrenocortical carcinoma cells. Our data showed that the IGF1R overexpression could be indicative of aggressive ACTs in children. However, in vitro treatments with high concentrations of OSI-906 (>1μM) showed limited reduction of cell viability, suggesting that OSI-906 alone could not be a suitable therapy to abolish carcinoma cell growth.

Combined steroidogenic characters of fetal adrenal and Leydig cells in childhood adrenocortical carcinoma

Although childhood adrenocortical carcinomas (c-ACCs) with a TP53 mutation are known to produce androgens, detailed steroidogenic characters have not been clarified. Here, we examined steroid metabolite profiles and expression patterns of steroidogenic genes in a c-ACC removed from the left adrenal position of a 2-year-old Brazilian boy with precocious puberty, using an atrophic left adrenal gland removed at the time of tumorectomy as a control. The c-ACC produced not only abundant dehydroepiandrosterone-sulfate but also a large amount of testosterone via the Δ5 pathway with Δ5-androstenediol rather than Δ4-androstenedione as the primary intermediate metabolite. Furthermore, the c-ACC was associated with elevated expressions of CYP11A1, CYP17A1, POR, HSD17B3, and SULT2A1, a low but similar expression of CYB5A, and reduced expressions of AKR1C3 (HSD17B5) and HSD3B2. Notably, a Leydig cell marker INSL3 was expressed at a low but detectable level in the c-ACC. Furthermore, molecular studies revealed a maternally inherited heterozygous germline TP53 mutation, and several post-zygotic genetic aberrations in the c-ACC including loss of paternally derived chromosome 17 with a wildtype TP53 and loss of maternally inherited chromosome 11 and resultant marked hyperexpression of paternally expressed growth promoting gene IGF2 and drastic hypoexpression of maternally expressed growth suppressing gene CDKN1C. These results imply the presence of combined steroidogenic properties of fetal adrenal and Leydig cells in this patient's c-ACC with a germline TP53 mutation and several postzygotic carcinogenic events.

Maternal-fetal conflict, genomic imprinting and mammalian vulnerabilities to cancer

Antagonistic coevolution between maternal and fetal genes, and between maternally and paternally derived genes may have increased mammalian vulnerability to cancer. Placental trophoblast has evolved to invade maternal tissues and evade structural and immunological constraints on its invasion. These adaptations can be co-opted by cancer in intrasomatic selection. Imprinted genes of maternal and paternal origin favour different degrees of proliferation of particular cell types in which they reside. As a result, the set of genes favouring greater proliferation will be selected to evade controls on cell-cycle progression imposed by the set of genes favouring lesser proliferation. The dynamics of stem cell populations will be a particular focus of this intragenomic conflict. Gene networks that are battlegrounds of intragenomic conflict are expected to be less robust than networks that evolve in the absence of conflict. By these processes, maternal-fetal and intragenomic conflicts may undermine evolved defences against cancer.

A Polymorphism in the FGFR4 Gene Is Associated With Risk of Neuroblastoma and Altered Receptor Degradation

BACKGROUND

Outcomes for children with high-risk neuroblastoma are poor, and improved understanding of the mechanisms underlying neuroblastoma pathogenesis, recurrence, and treatment resistance will lead to improved outcomes. Aberrant growth factor receptor expression and receptor tyrosine kinase signaling are associated with the pathogenesis of many malignancies. A germline polymorphism in the FGFR4 gene is associated with increased receptor expression and activity and with decreased survival, treatment resistance, and aggressive disease for many malignancies. We therefore investigated the role of this FGFR4 polymorphism in neuroblastoma pathogenesis.

MATERIALS AND METHODS

Germline DNA from neuroblastoma patients and matched controls was assessed for the FGFR4 Gly/Arg388 polymorphism by RT-PCR. Allele frequencies were assessed for association with neuroblastoma patient outcomes and prognostic features. Degradation rates of the FGFR4 Arg388 and Gly388 receptors and rates of receptor internalization into the late endosomal compartment were measured.

RESULTS

Frequency of the FGFR4 AA genotype and the prevalence of the A allele were significantly higher in patients with neuroblastoma than in matched controls. The Arg388 receptor demonstrated slower degradation than the Gly388 receptor in neuroblastoma cells and reduced internalization into multivesicular bodies.

CONCLUSIONS

The FGFR4 Arg388 polymorphism is associated with an increased prevalence of neuroblastoma in children, and this association may be linked to differences in FGFR4 degradation rates. Our study provides the first evidence of a role for FGFR4 in neuroblastoma, suggesting that FGFR4 genotype and the pathways regulating FGFR4 trafficking and degradation may be relevant for neuroblastoma pathogenesis.

Mouse Models Recapitulating Human Adrenocortical Tumors: What Is Lacking?

Adrenal cortex tumors are divided into benign forms, such as primary hyperplasias and adrenocortical adenomas (ACAs), and malignant forms or adrenocortical carcinomas (ACCs). Primary hyperplasias are rare causes of adrenocorticotropin hormone-independent hypercortisolism. ACAs are the most common type of adrenal gland tumors and they are rarely "functional," i.e., producing steroids. When functional, adenomas result in endocrine disorders, such as Cushing's syndrome (hypercortisolism) or Conn's syndrome (hyperaldosteronism). By contrast, ACCs are extremely rare but highly aggressive tumors that may also lead to hypersecreting syndromes. Genetic analyses of patients with sporadic or familial forms of adrenocortical tumors (ACTs) led to the identification of potentially causative genes, most of them being involved in protein kinase A (PKA), Wnt/β-catenin, and P53 signaling pathways. Development of mouse models is a crucial step to firmly establish the functional significance of candidate genes, to dissect mechanisms leading to tumors and endocrine disorders, and in fine to provide in vivo tools for therapeutic screens. In this article, we will provide an overview on the existing mouse models (xenografted and genetically engineered) of ACTs by focusing on the role of PKA and Wnt/β-catenin pathways in this context. We will discuss the advantages and limitations of models that have been developed heretofore and we will point out necessary improvements in the development of next generation mouse models of adrenal diseases.

Adrenocortical growth and cancer

The adrenal gland consists of two distinct parts, the cortex and the medulla. Molecular mechanisms controlling differentiation and growth of the adrenal gland have been studied in detail using mouse models. Knowledge also came from investigations of genetic disorders altering adrenal development and/or function. During embryonic development, the adrenal cortex acquires a structural and functional zonation in which the adrenal cortex is divided into three different steroidogenic zones. Significant progress has been made in understanding adrenal zonation. Recent lineage tracing experiments have accumulated evidence for a centripetal differentiation of adrenocortical cells from the subcapsular area to the inner part of the adrenal cortex. Understanding of the mechanism of adrenocortical cancer (ACC) development was stimulated by knowledge of adrenal gland development. ACC is a rare cancer with a very poor overall prognosis. Abnormal activation of the Wnt/β-catenin as well as the IGF2 signaling plays an important role in ACC development. Studies examining rare genetic syndromes responsible for familial ACT have played an important role in identifying genetic alterations in these tumors (like TP53 or CTNNB1 mutations as well as IGF2 overexpression). Recently, genomic analyses of ACT have shown gene expression profiles associated with malignancy as well as chromosomal and methylation alterations in ACT and exome sequencing allowed to describe the mutational landscape of these tumors. This progress leads to a new classification of these tumors, opening new perspectives for the diagnosis and prognostication of ACT. This review summarizes current knowledge of adrenocortical development, growth, and tumorigenesis.

Prevalence and functional consequence of TP53 mutations in pediatric adrenocortical carcinoma: a children's oncology group study

PURPOSE

Adrenocortical carcinoma (ACC) is a rare pediatric malignancy. It occurs in excess among individuals with the Li-Fraumeni syndrome, which results primarily from germline mutations in the TP53 gene. Prior series exploring frequencies of germline TP53 mutation among children with ACC have been small, geographically limited, or subject to referral bias. The functional consequence of mutations has not been related to phenotype. We provide a genotype-phenotype analysis of TP53 mutations in pediatric ACC and propose a model for tissue-specific effects based on adrenocortical ontogeny.

PATIENTS AND METHODS

Eighty-eight consecutive, unrelated children with ACC, unselected for family history, underwent germline TP53 sequencing. Rate and distribution of mutations were identified. Functional analysis was performed for novel TP53 variants. Correlation with the International Agency for Research on Cancer p53 database further delineated mutational distribution, association with family history, and risk for multiple primary malignancies (MPMs).

RESULTS

Germline mutations were present in 50% of children. These mutations did not correspond to the conventional hotspot mutations. There was a wide range of mutant protein function. Patients bearing alleles encoding protein with higher functionality were less likely to have a strong family cancer history, whereas those with greater loss of function had MPMs and/or positive family history. In patients with MPMs, ACC was the most frequent initial malignancy. Finally, we demonstrated age-dependent rates of TP53 mutation positivity.

CONCLUSION

TP53 mutations are prevalent in children with ACC but decline with age. Mutations result in a broad spectrum of functional loss. Effect of individual mutations may predict carrier and familial disease penetrance with potentially broad implications for clinical surveillance and counseling.

Pediatric adrenocortical tumors: what they can tell us on adrenal development and comparison with adult adrenal tumors

Adrenocortical tumors (ACT) in children are very rare and are most frequently diagnosed in the context of the Li-Fraumeni syndrome, a multiple cancer syndrome linked to germline mutations of the tumor suppressor gene TP53 with loss of heterozygosity in the tumors. A peak of children ACT incidence is present in the states of southern Brazil, where they are linked to the high prevalence in the population of a specific TP53 mutation (R337H). Children ACT have specific features distinguishing them from adult tumors in their pathogenetic mechanisms, genomic profiles, and prognosis. Epidemiological and molecular evidence suggests that in most cases they are derived from the fetal adrenal.

Regulation of the adrenocortical stem cell niche: implications for disease

Stem cells are endowed with the potential for self-renewal and multipotency. Pluripotent embryonic stem cells have an early role in the formation of the three germ layers (ectoderm, mesoderm and endoderm), whereas adult tissue stem cells and progenitor cells are critical mediators of organ homeostasis. The adrenal cortex is an exceptionally dynamic endocrine organ that is homeostatically maintained by paracrine and endocrine signals throughout postnatal life. In the past decade, much has been learned about the stem and progenitor cells of the adrenal cortex and the multiple roles that these cell populations have in normal development and homeostasis of the adrenal gland and in adrenal diseases. In this Review, we discuss the evidence for the presence of adrenocortical stem cells, as well as the various signalling molecules and transcriptional networks that are critical for the embryological establishment and postnatal maintenance of this vital population of cells. The implications of these pathways and cells in the pathophysiology of disease are also addressed.

Low expression of HLA-DRA, HLA-DPA1, and HLA-DPB1 is associated with poor prognosis in pediatric adrenocortical tumors (ACT)

BACKGROUND

Low expression of HLA class II antigens has been associated with more aggressive disease in several human malignancies including adult adrenocortical tumors (ACT), but their clinical relevance in pediatric ACT needs to be investigated.

PROCEDURE

This study analyzed the expression profile of three class II histocompatibility genes (HLA-DRA, HLA-DPA1, and HLA-DPB1) in 58 consecutive pediatric ACT (13 adenomas and 45 carcinomas) by quantitative real time PCR and their association with clinical and biological features. HLA-DPA1 protein level was determined by immunohistochemistry.

RESULTS

A significant association (P < 0.01) was observed between lower expression levels of the three genes analyzed and poor prognostic factors such as age ≥ 4 years, tumor size ≥ 200 cm(3), tumor weight ≥ 100 g, and metastatic disease; the presence of an unfavorable event and death. Underexpression of the HLA-DRA, HLA-DPA1, and HLA-DPB1 genes were associated with lower 5-year event-free survival (EFS) (P = 0.017, P < 0.001, and P = 0.017, respectively). Cox multivariate analysis showed that HLA-DPA1 was an independent prognostic factor (P = 0.029) when analyzed in association with stage IV, age and tumor size. Significantly lower EFS was also observed in patients with negative/weak immunostaining for HLA-DPA1 (P = 0.002). Similar results were observed when only patients classified as having carcinomas were analyzed.

CONCLUSION

Our results suggest that lower expression of HLA-DRA, HLA-DPA1, and HLA-DPB1 genes may contribute to more aggressive disease in pediatric ACT. HLA-DPA1 immunostaining may represent potential aggressiveness marker in this tumor.

Emerging therapy for adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a very rare and aggressive tumor with dismal outcomes. Best current treatments include complete surgical resection for localized resectable disease and systemic therapy with mitotane alone or in combination for advanced ACC. Advances in molecular genetic profiling of ACC have created multiple new targets for potential treatment options in ACC. This article reviews the current treatment options available for ACC and discusses the potential new targets identified through molecular profiling.

Adrenocortical carcinoma in children: first population-based clinicopathological study with long-term follow-up

Adrenocortical carcinoma (ACC) is rare in both adult and pediatric populations. Literature suggests significant differences between children and adults in presentation, histological properties and outcome. The aim of this first nationwide study on pediatric ACC was to describe the incidence, presentation, pathological characteristics, treatment and survival in The Netherlands. All ACC patients aged <20 years at diagnosis and registered in the population-based Netherlands Cancer Registry between 1993 and 2010 were included. Clinical data were extracted from medical records. Archival histological slides were collected via the Dutch Pathology Registry (PALGA). We compared our findings to all clinical studies on pediatric ACC that were found on PubMed. Based on the results, 12 patients were identified: 8 females and 4 males. The median age was 4.1 years (range 1.1-18.6). The population-based age-standardized incidence rate for patients <20 years was 0.18 per million person-years. Autonomous hormonal secretion was present in 10 patients. Seven patients were aged ≤4 years at diagnosis, 5 presented with localized disease and 2 with locally advanced disease. Five patients were aged ≥5 years, 3 presented with distant metastases and 1 with locally advanced disease. For all patients, histological examination displayed malignant characteristics. All patients aged ≤4 years at diagnosis survived; the median follow-up was 97 months (57-179 months). All patients aged ≥5 years died; the median survival was 6 months (0-38 months). Pediatric ACC is extremely rare in the Western world. The clinical outcome was remarkably better in patients aged ≤4 years. This is in accordance with less advanced stage of disease at presentation, yet contrasts with the presence of adverse histological characteristics. Clinical management in advanced disease is adapted from adult practice in the absence of evidence regarding pediatric ACC.

IGF2 promotes growth of adrenocortical carcinoma cells, but its overexpression does not modify phenotypic and molecular features of adrenocortical carcinoma

Insulin-like growth factor 2 (IGF2) overexpression is an important molecular marker of adrenocortical carcinoma (ACC), which is a rare but devastating endocrine cancer. It is not clear whether IGF2 overexpression modifies the biology and growth of this cancer, thus more studies are required before IGF2 can be considered as a major therapeutic target. We compared the phenotypical, clinical, biological, and molecular characteristics of ACC with or without the overexpression of IGF2, to address these issues. We also carried out a similar analysis in an ACC cell line (H295R) in which IGF2 expression was knocked down with si- or shRNA. We found no significant differences in the clinical, biological and molecular (transcriptomic) traits between IGF2-high and IGF2-low ACC. The absence of IGF2 overexpression had little influence on the activation of tyrosine kinase pathways both in tumors and in H295 cells that express low levels of IGF2. In IGF2-low tumors, other growth factors (FGF9, PDGFA) are more expressed than in IGF2-high tumors, suggesting that they play a compensatory role in tumor progression. In addition, IGF2 knock-down in H295R cells substantially impaired growth (>50% inhibition), blocked cells in G1 phase, and promoted apoptosis (>2-fold). Finally, analysis of the 11p15 locus showed a paternal uniparental disomy in both IGF2-high and IGF2-low tumors, but low IGF2 expression could be explained in most IGF2-low ACC by an additional epigenetic modification at the 11p15 locus. Altogether, these observations confirm the active role of IGF2 in adrenocortical tumor growth, but also suggest that other growth promoting pathways may be involved in a subset of ACC with low IGF2 expression, which creates opportunities for the use of other targeted therapies.

Next-generation sequencing of adrenocortical carcinoma reveals new routes to targeted therapies

Aims

Adrenocortical carcinoma (ACC) carries a poor prognosis and current systemic cytotoxic therapies result in only modest improvement in overall survival. In this retrospective study, we performed a comprehensive genomic profiling of 29 consecutive ACC samples to identify potential targets of therapy not currently searched for in routine clinical practice.

Methods

DNA from 29 ACC was sequenced to high, uniform coverage (Illumina HiSeq) and analysed for genomic alterations (GAs).

Results

At least one GA was found in 22 (76%) ACC (mean 2.6 alterations per ACC). The most frequent GAs were in TP53 (34%), NF1 (14%), CDKN2A (14%), MEN1 (14%), CTNNB1 (10%) and ATM (10%). APC, CCND2, CDK4, DAXX, DNMT3A, KDM5C, LRP1B, MSH2 and RB1 were each altered in two cases (7%) and EGFR, ERBB4, KRAS, MDM2, NRAS, PDGFRB, PIK3CA, PTEN and PTCH1 were each altered in a single case (3%). In 17 (59%) of ACC, at least one GA was associated with an available therapeutic or a mechanism-based clinical trial.

Conclusions

Next-generation sequencing can discover targets of therapy for relapsed and metastatic ACC and shows promise to improve outcomes for this aggressive form of cancer.

Sonic hedgehog signaling is active in human adrenal cortex development and deregulated in adrenocortical tumors

BACKGROUND

The sonic hedgehog (SHH) pathway plays a key role in rodent adrenal cortex development and is involved in tumorigenesis in several human tissues, but data in human adrenal glands are limited.

OBJECTIVES

The objectives of the study were to analyze the involvement of the SHH pathway in human adrenal development and tumorigenesis and the effects of SHH inhibition on an adrenocortical tumor (ACT) cell line.

PATIENTS AND METHODS

Expression of SHH pathway components was evaluated by immunohistochemistry in 51 normal adrenals (33 fetal) and 34 ACTs (23 pediatric) and by quantitative PCR in 81 ACTs (61 pediatric) and 19 controls (10 pediatric). The effects of SHH pathway inhibition on gene expression and cell viability in the NCI-H295A adrenocortical tumor cell line after cyclopamine treatment were analyzed.

RESULTS

SHH pathway proteins were present in fetal and postnatal normal adrenals and showed distinct patterns of spatiotemporal expression throughout development. Adult adrenocortical carcinomas presented with higher expression of PTCH1, SMO, GLI3, and SUFU compared with normal adult adrenal cortices. Conversely, pediatric ACTs showed lower mRNA expression of SHH, PTCH1, SMO, GLI1, and GLI3 compared with normal pediatric adrenal cortices. In vitro treatment with cyclopamine resulted in decreased GLI3, SFRP1, and CTNNB1 mRNA expression and β-catenin staining as well as decreased cell viability.

CONCLUSIONS

The SHH pathway is active in human fetal and postnatal adrenals, up-regulated in adult adrenocortical carcinomas, and down-regulated in pediatric ACTs. SHH pathway antagonism impaired cell viability. The SHH pathway is deregulated in ACTs and might provide a new target therapy to be explored.

Adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy, often with an unfavorable prognosis. Here we summarize the knowledge about diagnosis, epidemiology, pathophysiology, and therapy of ACC. Over recent years, multidisciplinary clinics have formed and the first international treatment trials have been conducted. This review focuses on evidence gained from recent basic science and clinical research and provides perspectives from the experience of a large multidisciplinary clinic dedicated to the care of patients with ACC.

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.

Molecular markers and targeted therapies for adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a lethal disease with poor prognosis and lack of effective therapeutic options. Systemic treatment is often employed to treat patients with advanced ACC, but outcomes are disappointing. During the last decade, some of the causative genetic mutations in sporadic ACCs have been identified. Molecular analysis has had a significant impact on the understanding of the pathogenetic mechanism of ACC development and the evaluation of prognostic and predictive markers. Preclinical investigations and clinical trials of tyrosine kinase inhibitors and anti-angiogenic compounds have been initiated to seek target therapy of ACCs. This review summarizes the current view of molecular alterations involved in the pathophysiology of adrenocortical carcinogenesis. The rationale for testing targeted therapies of ACC is also presented.

Beyond steroidogenesis: novel target genes for SF-1 discovered by genomics

Steroidogenic Factor-1 (SF-1) is a nuclear receptor transcription factor that has an essential role in the development of adrenal glands and gonads and in the regulation of steroidogenic gene expression. Recent studies using genomic approaches have revealed that SF-1 also has an important role in regulating proliferation of adrenocortical cells and have revealed its role in the control of a variety of biological processes as diverse as angiogenesis, adhesion to the extracellular matrix, cytoskeleton dynamics, transcriptional and post-transcriptional regulation of gene expression and apoptosis in the adrenal cortex. The identification of the complete set of SF-1 target genes will be of great importance to open new avenues for therapeutic intervention in adrenal diseases.