The molecular genetics of adrenocortical carcinoma

Estrogen Related Receptor Alpha (ERRα) a Bridge between Metabolism and Adrenocortical Cancer Progression

Simple Summary

Adrenocortical carcinoma (ACC) is a rare and highly aggressive tumor associated with a very poor prognosis, mostly due to a high risk of recurrence and limited therapeutic options. The identification of “master regulators” of the metabolic changes occurring in cancer cells could offer new targets for innovative therapies. Such a strategy has never been used against ACC progression. In this study, we identify ERRα as key player in ACC metabolism and its targeting can prevent progression to a more aggressive phenotype. The development of new therapeutic strategies to selectively target ERRα in the adrenal with a selective antagonist would hinder ACC progression, avoiding off-target effects.

Abstract

The aim of this study was to investigate the metabolic changes that occur in adrenocortical cancer (ACC) cells in response to the modulation of Estrogen Related Receptor (ERR)α expression and the impact on ACC progression. Proteomics analysis and metabolic profiling highlighted an important role for ERRα in the regulation of ACC metabolism. Stable ERRα overexpression in H295R cells promoted a better mitochondrial fitness and prompted toward a more aggressive phenotype characterized by higher Vimentin expression, enhanced cell migration and spheroids formation. By contrast, a decrease in ERRα protein levels, by molecular (short hairpin RNA) and pharmacological (inverse agonist XCT790) approaches modified the energetic status toward a low energy profile and reduced Vimentin expression and ability to form spheroids. XCT790 produced similar effects on two additional ACC cell lines, SW13 and mitotane-resistant MUC-1 cells. Our findings show that ERRα is able to modulate the metabolic profile of ACC cells, and its inhibition can strongly prevent the growth of mitotane-resistant ACC cells and the progression of ACC cell models to a highly migratory phenotype. Consequently, ERRα can be considered an important target for the design of new therapeutic strategies to fight ACC progression.

Estrogen Receptors-Mediated Apoptosis in Hormone-Dependent Cancers

It is known that estrogen stimulates growth and inhibits apoptosis through estrogen receptor(ER)-mediated mechanisms in many cancer cell types. Interestingly, there is strong evidence that estrogens can also induce apoptosis, activating different ER isoforms in cancer cells. It has been observed that E2/ERα complex activates multiple pathways involved in both cell cycle progression and apoptotic cascade prevention, while E2/ERβ complex in many cases directs the cells to apoptosis. However, the exact mechanism of estrogen-induced tumor regression is not completely known. Nevertheless, ERs expression levels of specific splice variants and their cellular localization differentially affect outcome of estrogen-dependent tumors. The goal of this review is to provide a general overview of current knowledge on ERs-mediated apoptosis that occurs in main hormone dependent-cancers. Understanding the molecular mechanisms underlying the induction of ER-mediated cell death will be useful for the development of specific ligands capable of triggering apoptosis to counteract estrogen-dependent tumor growth.

SIRT1 is involved in adrenocortical cancer growth and motility

Adrenocortical cancer (ACC) is a rare tumour with unfavourable prognosis, lacking an effective treatment. This tumour is characterized by IGF‐II (insulin‐like growth factor II) overproduction, aromatase and ERα (oestrogen receptor alpha) up‐regulation. Previous reports suggest that ERα expression can be regulated by sirt1 (sirtuin 1), a nicotinamide adenine dinucleotide (NAD+)‐dependent class III histone deacetylases that modulates activity of several substrates involved in cellular stress, metabolism, proliferation, senescence, protein degradation and apoptosis. Nevertheless, sirt1 can act as a tumour suppressor or oncogenic protein. In this study, we found that in H295R and SW13 cell lines, sirt1 expression is inhibited by sirtinol, a potent inhibitor of sirt1 activity. In addition, sirtinol is able to decrease ACC cell proliferation, colony and spheroids formation and to activate the intrinsic apoptotic mechanism. Particularly, we observed that sirtinol interferes with E2/ERα and IGF1R (insulin growth factor 1 receptor) pathways by decreasing receptors expression. Sirt1 involvement was confirmed by using a specific sirt1 siRNA. More importantly, we observed that sirtinol can synergize with mitotane, a selective adrenolitic drug, in inhibiting adrenocortical cancer cell growth. Collectively, our data reveal an oncogenic role for sirt1 in ACC and its targeting could implement treatment options for this type of cancer.

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.

New targeted therapies for adrenocortical carcinomas

Adrenocortical carcinoma (ACC) is a rare malignancy with poor prognosis. It has undergone in-depth clinical and laboratory investigations, with the help of the most important research groups all over the world. Nonetheless the cure for this kind of neoplasia is not right around the corner, given its complexity and multi-faceted feature, that lead researchers to think at "one person one ACC." Currently total resection is the most concrete option for ACC patients, whenever possible. Mitotane remains the main drug for primary or adjuvant therapy, but gives partial and unsatisfactory therapeutic results, especially in metastatic ACC. This prompted the researchers to find other ways to fight against this malignancy: targeted therapy seems the most promising answer, as it is based on biomolecular and genetic cancer signature. Numerous specific targets were explored for the treatment of ACC, such as those involving angiogenesis, steroidogenesis, Wnt/β-catenin pathway and many others key factors. Even if large efforts have been made, no effective target therapy entered in the clinical use. This data should not be considered only as detrimental, rather it should propel scientific research to invest more resources into the therapeutic exploration of ACC and in particular on the most promising strategy, the targeted therapy.

Pediatric adrenocortical neoplasms: immunohistochemical expression of p57 identifies loss of heterozygosity and abnormal imprinting of the 11p15.5

BACKGROUND

Diagnosis of adrenocortical neoplasms (ACN), in pediatric age, is based on Wieneke criteria. The p57, a cyclin-dependent kinase inhibitor, acts to negatively regulate cell proliferation and is frequently found dysregulated in cancer. The identification of loss of heterozygosity (LOH) of 11p15, containing the p57 gene, could be a tool for differential diagnosis of benign and malignant ACN.

METHODS

Immunohistochemistry with anti-p57 and microsatellite markers analysis of 11p15 region to value LOH were made in both ACN and surrounded normal adrenal cortex.

RESULTS

Nine ACN, two clinically benign, two uncertain, and five malignant, were diagnosed. Positive p57 cells were evident in normal adrenal cortex and in one histologically benign ACN. A low/absent expression of p57 was documented in eight ACN independently from the classification on the basis of pathological and clinical criteria. Microsatellite marker analysis confirmed the LOH of 11p15 region in the same ACN.

CONCLUSION

LOH of 11p15 has a high prognostic value suggesting the p57 gene is important in ACN pathogenesis. Immunohistochemistry for p57 is a simple and cheap tool that can be used to quickly identify LOH of 11p15 in ACN.

New insights and future perspectives in the therapeutic strategy of adrenocortical carcinoma (Review)

Adrenocortical carcinoma (ACC) is a rare endocrine malignancy with an incidence ranging from 0.7 to 2.0 cases/million people per year. Hypercortisolism represents the most common clinical presentation in many patients although, less frequently, some ACC secreting androgens and estrogens are even more pathognomonic compared to cortisol secretion. Currently, radical surgery, when feasible, is still the only curative therapy. Mitotane, an adrenolytic drug, is used in the adjuvant setting and in combination with chemotherapy drugs in metastatic disease. The use of radiotherapy remains controversial, being indicated only in selected cases. New targeted therapies, such as insulin growth factor-1 (IGF-1), mammalian-target of rapamycin (m-TOR), vascular endothelial growth factor (VEGF) inhibitors and others, have recently been investigated with disappointing clinical results. The partial effectiveness of current treatments mandates the need for new therapeutic strategies against this tumor.

C-MYC modulation induces responsiveness to paclitaxel in adrenocortical cancer cell lines

C-MYC is overexpressed in many types of cancer linked to poor prognosis. We examined the c-Myc protein expression in adrenocortical cancer (ACC) cells to investigate the role of this protein in the neoplasm, its involvement in chemotherapy and finally to determine whether c-Myc could be considered a prognostic factor in patients with ACC. H295R and SW13 cell lines were treated with paclitaxel. c-Myc overexpressing cell clones were achieved by transfecting the H295R cell line with the pcDNA3-hMYC plasmid expressing the full-lengh C-MYC coding sequence. The SW13 cell line was transfected with siRNA oligonucleotides for C-MYC. Cell cycle analysis was evaluated by flow cytometry. c-Myc, cyclin B1 and pro caspase expression levels were evaluated by western blot analysis. We found that expression of c-Myc was highly expressed in the SW13 cells, whereas the protein was undetectable in the H295R cells. Different doses of paclitaxel were required in the two ACC cell line to induce a block in the G2 phase, characterized by increased cyclin B1 levels and to induce apoptosis by pro-caspase-3 activation. Interestingly, the silencing of C-MYC mRNA prevented paclitaxel induced apoptosis in SW13 cells, whereas in the H295R cells the overexpression of C-MYC rendered the cells more prone to growth inhibition after paclitaxel exposure. The present study directly demonstrates that C-MYC plays a central role in controlling proliferation in ACC cells after paclitaxel treatment and that c-Myc could be considered as a marker for predicting response to chemotherapeutic agents in ACC cell lines.

Amplification of the insulin-like growth factor 1 receptor gene is a rare event in adrenocortical adenocarcinomas: searching for potential mechanisms of overexpression

Context. IGF1R overexpression appears to be a prognostic biomarker of metastatic pediatric adrenocortical tumors. However, the molecular mechanisms that are implicated in its upregulation remain unknown. Aim. To investigate the potential mechanisms involved in IGF1R overexpression. Patients and Methods. We studied 64 adrenocortical tumors. IGF1R copy number variation was determined in all patients using MLPA and confirmed using real time PCR. In a subgroup of 32 patients, automatic sequencing was used to identify IGF1R allelic variants and the expression of microRNAs involved in IGF1R regulation by real time PCR. Results. IGF1R amplification was detected in an adrenocortical carcinoma that was diagnosed in a 46-year-old woman with Cushing's syndrome and virilization. IGF1R overexpression was demonstrated in this case. In addition, gene amplification of other loci was identified in this adrenocortical malignant tumor, but no IGF1R copy number variation was evidenced in the remaining cases. Automatic sequencing revealed three known polymorphisms but they did not correlate with its expression. Expression of miR-100, miR-145, miR-375, and miR-126 did not correlate with IGF1R expression. Conclusion. We demonstrated amplification and overexpression of IGF1R gene in only one adrenocortical carcinoma, suggesting that these combined events are uncommon. In addition, IGF1R polymorphisms and abnormal microRNA expression did not correlate with IGF1R upregulation in adrenocortical tumors.

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.

Current and emerging therapeutic options in adrenocortical cancer treatment

Adrenocortical carcinoma (ACC) is a very rare endocrine tumour, with variable prognosis, depending on tumour stage and time of diagnosis. The overall survival is five years from detection. Radical surgery is considered the therapy of choice in the first stages of ACC. However postoperative disease-free survival at 5 years is only around 30% and recurrence rates are frequent. o,p'DDD (ortho-, para'-, dichloro-, diphenyl-, dichloroethane, or mitotane), an adrenolytic drug with significant toxicity and unpredictable therapeutic response, is used in the treatment of ACC. Unfortunately, treatment for this aggressive cancer is still ineffective. Over the past years, the growing interest in ACC has contributed to the development of therapeutic strategies in order to contrast the neoplastic spread. In this paper we discuss the most promising therapies which can be used in this endocrine neoplasia.

GATA4 is a critical regulator of gonadectomy-induced adrenocortical tumorigenesis in mice

In response to gonadectomy certain inbred mouse strains develop sex steroidogenic adrenocortical neoplasms. One of the hallmarks of neoplastic transformation is expression of GATA4, a transcription factor normally present in gonadal but not adrenal steroidogenic cells of the adult mouse. To show that GATA4 directly modulates adrenocortical tumorigenesis and is not merely a marker of gonadal-like differentiation in the neoplasms, we studied mice with germline or conditional loss-of-function mutations in the Gata4 gene. Germline Gata4 haploinsufficiency was associated with attenuated tumor growth and reduced expression of sex steroidogenic genes in the adrenal glands of ovariectomized B6D2F1 and B6AF1 mice. At 12 months after ovariectomy, wild-type B6D2F1 mice had biochemical and histological evidence of adrenocortical estrogen production, whereas Gata4(+/-) B6D2F1 mice did not. Germline Gata4 haploinsufficiency exacerbated the secondary phenotype of postovariectomy obesity in B6D2F1 mice, presumably by limiting ectopic estrogen production in the adrenal glands. Amhr2-cre-mediated deletion of floxed Gata4 (Gata4(F)) in nascent adrenocortical neoplasms of ovariectomized B6.129 mice reduced tumor growth and the expression of gonadal-like markers in a Gata4(F) dose-dependent manner. We conclude that GATA4 is a key modifier of gonadectomy-induced adrenocortical neoplasia, postovariectomy obesity, and sex steroidogenic cell differentiation.

Molecular markers of adrenocortical tumors

Adrenocortical tumors are common and incidentally discovered in up to 14% of axial imaging studies performed for other indications. Most of these tumors are nonfunctioning but may require removal because of the risk of adrenocortical carcinoma. Unfortunately, most clinical and imaging features are still not accurate enough to allow definitive diagnosis and an increasing number of patients undergo adrenalectomy to exclude a cancer diagnosis. Adrenocortical carcinoma is an aggressive malignancy with no effective therapy for patients with locally advanced and metastatic disease. Studies using new genomic approaches including mRNA, miRNA, methylation, and CGH profiling have identified dysregulated genes and pathways that may have clinical implications in improved molecular diagnosis and prognostication of adrenocortical cancer (ACC). In this review, we highlight recent advances in the molecular diagnosis of adrenocortical tumors.

Clinical and molecular aspects of a pediatric metachronous adrenocortical tumor

The occurrence of metachronous adrenocortical carcinoma has rarely been described. We report a case of a child with virilizing adrenocortical metachronous tumors that, despite several metastases, presented long-term survival (15 years). We analyzed in this tumor IGF2, IGF1R and FGFR4 gene expression, and evaluated the presence of p.R337H germline p53 mutation and somatic CTNNB1 mutation. IGF2 gene was over-expressed in both left (Weiss score 5) and right (Weiss 7) adrenocortical tumors. IGF1R expression levels were higher in the right adrenocortical tumor. FGFR4 over-expression was also detected in the right adrenocortical tumor. In addition, this patient harbors the germline p.R337H p53 mutation and loss of heterozygosity (LOH) was detected in the tumors. No somatic CTNNB1 mutations were found in both tumors. In conclusion, we demonstrated in this unusual case the over-expression of growth signaling pathways, which are molecular mechanisms previously related to adrenocortical tumorigenesis. Furthermore, the absence of somatic CTNNB1 mutations, which is a molecular marker of poor prognosis in adults, might be related to the long-term survival of this patient.

Targeting insulin-like growth factor axis in hepatocellular carcinoma

The insulin-like growth factor (IGF) axis contains ligands, receptors, substrates, and ligand binding proteins. The essential role of IGF axis in hepatocellular carcinoma (HCC) has been illustrated in HCC cell lines and in animal xenograft models. Preclinical evidence provides ample indication that all four components of IGF axis are crucial in the carcinogenic and metastatic potential of HCC. Several strategies targeting this system including monoclonal antibodies against the IGF 1 receptor (IGF-1R) and small molecule inhibitors of the tyrosine kinase function of IGF-1R are under active investigation. This review describes the most up-to-date understanding of this complex axis in HCC, and provides relevant information on clinical trials targeting the IGF axis in HCC with a focus on anti-IGF-1R approach. IGF axis is increasingly recognized as one of the most relevant pathways in HCC and agents targeting this axis can potentially play an important role in the treatment of HCC.

Targeting insulin-like growth factor axis in hepatocellular carcinoma

The insulin-like growth factor (IGF) axis contains ligands, receptors, substrates, and ligand binding proteins. The essential role of IGF axis in hepatocellular carcinoma (HCC) has been illustrated in HCC cell lines and in animal xenograft models. Preclinical evidence provides ample indication that all four components of IGF axis are crucial in the carcinogenic and metastatic potential of HCC. Several strategies targeting this system including monoclonal antibodies against the IGF 1 receptor (IGF-1R) and small molecule inhibitors of the tyrosine kinase function of IGF-1R are under active investigation. This review describes the most up-to-date understanding of this complex axis in HCC, and provides relevant information on clinical trials targeting the IGF axis in HCC with a focus on anti-IGF-1R approach. IGF axis is increasingly recognized as one of the most relevant pathways in HCC and agents targeting this axis can potentially play an important role in the treatment of HCC.

Adrenal lesions in acromegaly: do metabolic aspects and aryl hydrocarbon receptor interacting protein gene have a role? Evaluation at baseline and after long-term follow-up

BACKGROUND

Adrenal lesions are discovered in acromegaly more frequently than in general population, without relationship with primary disease. Some patients, carriers of aryl hydrocarbon receptor interacting protein (AIP) gene mutations, developed an adrenal neoplasm.

AIM

To evaluate the role of metabolic and genetic aspects and the follow-up of adrenal nodules in acromegaly.

MATERIAL AND METHODS

We studied 69 acromegalic patients (30 male and 39 female, 56 ± 15 yr) who had been referred to the Endocrinology Unit of Padua. In all patients we determined body mass index (BMI) and waist-to-hip ratio (WHR); we performed an oral glucose tolerance test (OGTT) whenever possible. If adrenal computed tomography revealed a lesion, the patient underwent an endocrine and genetic study.

RESULTS

Adrenal lesions were identified in 14 patients and were not related to gender, duration of disease, GH or IGF-I concentrations, basal and after-OGTT glucose and insulin levels, log(HOMA-IR) and Quantitative Insulin Sensitivity Check Index (QUICKI) values, whereas BMI and WHR were higher in patients with adrenal lesions. Baseline endocrine and radiological study revealed benign lesions; during mean 4-yr follow-up none of the patients showed hormone excess, even though some lesions increased in size. We did not find any mutation in AIP gene, except heterozygous silent alteration (T48T).

CONCLUSIONS

The frequency of non-functioning adrenal lesions in acromegaly is not associated with the considered aspects, except BMI and WHR. The prolonged follow-up showed that these lesions have a tendency to increase in size independently of the control of acromegaly, so a morphological follow- up is recommended.

Educational paper: screening in cancer predisposition syndromes: guidelines for the general pediatrician

Improvements in our understanding of the genetic basis of human disease and increased utilization of genetic testing have identified a variety of heritable disorders associated with the onset of benign or malignant neoplasms during childhood. In many cases, the optimal management of affected children is dependent upon the early detection and treatment of tumors. Surveillance strategies based on the natural history of these lesions are often complex, requiring clinical examinations and radiologic and laboratory studies that evolve over a patient's lifetime. A general pediatrician may be the first to suspect one of these disorders in a patient, or may be faced with questions regarding genetic testing, cancer risk, and cancer screening. The pediatrician may also coordinate and interpret the results of specific surveillance studies. In this review, we present the genetic etiology, presentation, natural history, and surveillance recommendations for four disparate hereditary tumor predisposing syndromes, including Beckwith-Wiedemann syndrome/idiopathic hemihyperplasia, von Hippel-Lindau disease, Li-Fraumeni syndrome, and rhabdoid tumor/schwannomatosis. These examples are meant to offer the clinician practical recommendations as well as a framework upon which to base the understanding and management of other conditions associated with an increased risk to develop tumors in childhood.

Compensatory insulin receptor (IR) activation on inhibition of insulin-like growth factor-1 receptor (IGF-1R): rationale for cotargeting IGF-1R and IR in cancer

Insulin-like growth factor-1 receptor (IGF-1R) is a receptor tyrosine kinase (RTK) and critical activator of the phosphatidylinositol 3-kinase-AKT pathway. IGF-1R is required for oncogenic transformation and tumorigenesis. These observations have spurred anticancer drug discovery and development efforts for both biological and small-molecule IGF-1R inhibitors. The ability for one RTK to compensate for another to maintain tumor cell viability is emerging as a common resistance mechanism to antitumor agents targeting individual RTKs. As IGF-1R is structurally and functionally related to the insulin receptor (IR), we asked whether IR is tumorigenic and whether IR-AKT signaling contributes to resistance to IGF-1R inhibition. Both IGF-1R and IR(A) are tumorigenic in a mouse mammary tumor model. In human tumor cells coexpressing IGF-1R and IR, bidirectional cross talk was observed following either knockdown of IR expression or treatment with a selective anti-IGF-1R antibody, MAB391. MAB391 treatment resulted in a compensatory increase in phospho-IR, which was associated with resistance to inhibition of IRS1 and AKT. In contrast, treatment with OSI-906, a small-molecule dual inhibitor of IGF-1R/IR, resulted in enhanced reduction in phospho-IRS1/phospho-AKT relative to MAB391. Insulin or IGF-2 activated the IR-AKT pathway and decreased sensitivity to MAB391 but not to OSI-906. In tumor cells with an autocrine IGF-2 loop, both OSI-906 and an anti-IGF-2 antibody reduced phospho-IR/phospho-AKT, whereas MAB391 was ineffective. Finally, OSI-906 showed superior efficacy compared with MAB391 in human tumor xenograft models in which both IGF-1R and IR were phosphorylated. Collectively, these data indicate that cotargeting IGF-1R and IR may provide superior antitumor efficacy compared with targeting IGF-1R alone.

The evolving field of tyrosine kinase inhibitors in the treatment of endocrine tumors

Activation of tyrosine kinase receptors (TKRs) and their related pathways has been associated with development of endocrine tumors. Compounds that target and inactivate the kinase function of these receptors, tyrosine kinase inhibitors (TKIs), are now being applied to the treatment of endocrine tumors. Recent clinical trials of TKIs in patients with advanced thyroid cancer, islet cell carcinoma, and carcinoid have shown promising preliminary results. Significant reductions in tumor size have been described in medullary and papillary thyroid carcinoma, although no complete responses have been reported. Case reports have described significant tumor volume reductions of malignant pheochromocytomas and paragangliomas. In addition, these compounds showed an initial tumoricidal or apoptotic response followed by long-term static effects on tumor growth. Despite the promising preliminary results, this class of therapeutic agents has a broad spectrum of adverse effects, mediated by inhibition of kinase activities in normal tissues. These adverse effects will have to be balanced with their benefit in clinical use. New strategies will have to be applied in clinical research to achieve optimal benefits. In this review, we will address the genetic alterations of TKRs, the rationale for utilizing TKIs for endocrine tumors, and current information on tumor and patient responses to specific TKIs. We will also discuss the adverse effects related to TKI treatment and the mechanisms involved. Finally, we will summarize the challenges associated with use of this class of compounds and potential solutions.

Surgical management of nonmultiple endocrine neoplasia endocrinopathies: state-of-the-art review

The development of genetic testing has given patients with familial endocrine diseases the opportunity to be identified earlier in life. The importance of this technological advancement cannot be underestimated, as some of these heritable diseases have significant potential for malignancy. This article focuses on the identification and surgical management of familial endocrinopathies of the thyroid, parathyroid, adrenal glands, and pancreas. Familial endocrinopathies discussed include hereditary nonmedullary carcinoma of the thyroid, Cowden disease, familial adenomatous polyposis, Carney complex, Werner syndrome, familial medullary thyroid carcinoma, Pendred syndrome, hereditary hyperparathyroidism jaw-tumor syndrome, familial isolated hyperparathyroidism, Beckwith- Wiedemann syndrome, Li-Fraumeni syndrome, neurofibromatosis I, von Hippel-Lindau disease, and tuberous sclerosis.

Adrenal cortical neoplasms in children: why so many carcinomas and yet so many survivors?

Adrenal cortical neoplasms in children are represented by a disproportionate number of cases that have been diagnosed pathologically as adrenocortical carcinomas (ACCs)-as many as 90% of all cortical tumors in some pediatric series. Like other solid malignancies of childhood, over half of ACCs present in the first 4 years of life in over 50% of cases. Most are sporadically occurring neoplasms, but ACCs are a manifestation of Beckwith-Wiedemann and Li-Fraumeni syndromes. Despite the fact that the microscopic features are often quite atypical and identical in many respects to ACCs in adults, the clinical outcome is favorable in 70% or more of cases. Tumor weight is seemingly a significant determinant in prognosis at a threshold of greater than 400 g. A risk assessment system is proposed that incorporates tumor weight, localization of tumor to the gland without invasion into the surrounding tissues or organs, and absence of metastasis.

Review paper: origin and molecular pathology of adrenocortical neoplasms

Neoplastic adrenocortical lesions are common in humans and several species of domestic animals. Although there are unanswered questions about the origin and evolution of adrenocortical neoplasms, analysis of human tumor specimens and animal models indicates that adrenocortical tumorigenesis involves both genetic and epigenetic alterations. Chromosomal changes accumulate during tumor progression, and aberrant telomere function is one of the key mechanisms underlying chromosome instability during this process. Epigenetic changes serve to expand the size of the uncommitted adrenal progenitor population, modulate their phenotypic plasticity (i.e., responsiveness to extracellular signals), and increase the likelihood of subsequent genetic alterations. Analyses of heritable and spontaneous types of human adrenocortical tumors documented alterations in either cell surface receptors or their downstream effectors that impact neoplastic transformation. Many of the mutations associated with benign human adrenocortical tumors result in dysregulated cyclic adenosine monophosphate signaling, whereas key factors and/or signaling pathways associated with adrenocortical carcinomas include dysregulated expression of the IGF2 gene cluster, activation of the Wnt/beta-catenin pathway, and inactivation of the p53 tumor suppressor. A better understanding of the factors and signaling pathways involved in adrenal tumorigenesis is necessary to develop targeted pharmacologic and genetic therapies.

In search of adrenocortical stem and progenitor cells

Scientists have long hypothesized the existence of tissue-specific (somatic) stem cells and have searched for their location in different organs. The theory that adrenocortical organ homeostasis is maintained by undifferentiated stem or progenitor cells can be traced back nearly a century. Similar to other organ systems, it is widely believed that these rare cells of the adrenal cortex remain relatively undifferentiated and quiescent until needed to replenish the organ, at which time they undergo proliferation and terminal differentiation. Historical studies examining cell cycle activation by label retention assays and regenerative potential by organ transplantation experiments suggested that the adrenocortical progenitors reside in the outer periphery of the adrenal gland. Over the past decade, the Hammer laboratory, building on this hypothesis and these observations, has endeavored to understand the mechanisms of adrenocortical development and organ maintenance. In this review, we summarize the current knowledge of adrenal organogenesis. We present evidence for the existence and location of adrenocortical stem/progenitor cells and their potential contribution to adrenocortical carcinomas. Data described herein come primarily from studies conducted in the Hammer laboratory with incorporation of important related studies from other investigators. Together, the work provides a framework for the emerging somatic stem cell field as it relates to the adrenal gland.

New methods for investigating experimental human adrenal tumorigenesis

Adenomas and nodules of the human adrenal cortex are common, whereas adrenocortical carcinomas are rare. Genes such as IGF2 have been suggested to be important in human adrenocortical tumorigenesis but their role has not been directly investigated. We describe here elements of a system in which hypotheses concerning the molecular basis for the formation of benign and malignant adrenocortical lesions can be experimentally tested. Various viral vectors have been employed in the study of adrenocortical cell biology. Because of the low proliferative rate of primary human adrenocortical (pHAC) cells, a lentiviral system is ideal for transducing these cells with genes that may alter their characteristics or cause them to acquire benign or malignant tumorigenicity. Cultures of pHAC cells were highly infectible with lentiviruses and showed a higher proliferative potential when transduced with a lentivirus encoding IGF2. For tumorigenesis studies of genetically modified adrenocortical cells, we use RAG2(-/-), gammac(-/-) mice. Using this immunodeficient mouse model, we established an orthotopic intra-adrenal cell transplantation technique for adrenocortical cells that should be of value for future studies of the experimental conversion of human adrenocortical cells to a benign or malignant tumorigenic state.

E3 ubiquitin ligase RNF31 cooperates with DAX-1 in transcriptional repression of steroidogenesis

Genetic and experimental evidence points to a critical involvement of the atypical mammalian orphan receptor DAX-1 in reproductive development and steroidogenesis. Unlike conventional nuclear receptors, DAX-1 appears not to function as a DNA-bound transcription factor. Instead, it has acquired the capability to act as a transcriptional corepressor of steroidogenic factor 1 (SF-1). The interplay of DAX-1 and SF-1 is considered a central, presumably ligand-independent element of adrenogonadal development and function that requires tight regulation. This raises a substantial interest in identifying its modulators and the regulatory signals involved. Here, we uncover molecular mechanisms that link DAX-1 to the ubiquitin modification system via functional interaction with the E3 ubiquitin ligase RNF31. We demonstrate that RNF31 is coexpressed with DAX-1 in steroidogenic tissues and participates in repressing steroidogenic gene expression. We provide evidence for the in vivo existence of a corepressor complex containing RNF31 and DAX-1 at the promoters of the StAR and CYP19 genes. Our data suggest that RNF31 functions to stabilize DAX-1, which might be linked to DAX-1 monoubiquitination. In conclusion, RNF31 appears to be required for DAX-1 to repress transcription, provides means to regulate DAX-1 in ligand-independent ways, and emerges as a relevant coregulator of steroidogenic pathways governing physiology and disease.

Discerning malignancy in resected adrenocotical tumors

BACKGROUND

The number of adrenocortical tumors discovered incidentally has recently increased owing to the advent of imaging techniques. The most important diagnostic point in evaluation of resected specimens of these tumors is to discern malignancy to determine postoperative management of the patients.

OBJECTIVE/METHODS

To determine what the effective methods of discerning malignancy in resected specimens of adrenocortical tumors are at this juncture. To provide relevant and practical information pertinent to those involved in the management of patients with adrenocortical tumors.

CONCLUSION

Careful macroscopic evaluation, including the selection of the specimens submitted and application of the criteria of Weiss for histological diagnosis, is still considered the 'gold standard' for diagnosis of adrenocortical carcinoma. However, it is important to recognize its limitations in the diagnosis of adrenocortical oncocytoma and pediatric adrenocortical tumors. The auxiliary methods that may be of clinical relevance at this juncture include the analysis of the Ki67/MIB-1 labeling index and IGF-II expression in the tumors.