Combination of sorafenib and everolimus impacts therapeutically on adrenocortical tumor models

The mTOR-inhibitor everolimus reduces hypervolemia in patients with primary aldosteronism

BACKGROUND

We recently showed in a proof-of-concept study that treating individuals with primary aldosteronism with the mTOR-inhibitor everolimus decreases home blood pressure and renin suppression overall, and markedly reduces aldosterone levels in a subset of individuals. Based on these findings, the question arose whether the effects of everolimus were also mediated via aldosterone-independent mechanisms. Here, we undertook an exploratory, secondary analysis of above-mentioned study to comprehensively investigate how everolimus impacted the hemodynamic status of the study participants, which in turn could elucidate these mechanisms.

METHODS

Hemodynamic parameters were measured in study participants with primary aldosteronism at baseline, after treatment with everolimus 0.75 mg orally twice daily for 2 weeks and after a 2-week wash-out. Of the 14 participants, 10 participants had complete data sets for peripheral and central blood pressure, heart rate and pulse wave velocity, and 7 participants had complete data sets for cardiac index, inotropic state index, left stroke work index and stroke systemic vascular resistance index that could be analyzed. Parameters were acquired by brachial oscillometry (Mobil-o-graph PWA) and thoracic electrical bioimpedance (HOTMAN® System).

RESULTS

After treatment with everolimus, peripheral (P=0.049) and central (P=0.037) diastolic blood pressure, as well as hypervolemia (P=0.008) were significantly decreased. Likewise, peripheral (P=0.073) and central systolic blood pressure (P=0.166) trended downwards.

CONCLUSIONS

Everolimus lowers central and peripheral blood pressure in individuals with primary aldosteronism, possibly by decreasing primary aldosteronism-induced hypervolemia and preload.

Three Dimensional Models of Endocrine Organs and Target Tissues Regulated by the Endocrine System

Immortalized cell lines originating from tumors and cultured in monolayers in vitro display consistent behavior and response, and generate reproducible results across laboratories. However, for certain endpoints, these cell lines behave quite differently from the original solid tumors. Thereby, the homogeneity of immortalized cell lines and two-dimensionality of monolayer cultures deters from the development of new therapies and translatability of results to the more complex situation in vivo. Organoids originating from tissue biopsies and spheroids from cell lines mimic the heterogeneous and multidimensional characteristics of tumor cells in 3D structures in vitro. Thus, they have the advantage of recapitulating the more complex tissue architecture of solid tumors. In this review, we discuss recent efforts in basic and preclinical cancer research to establish methods to generate organoids/spheroids and living biobanks from endocrine tissues and target organs under endocrine control while striving to achieve solutions in personalized medicine.

Clinical results of the EVESOR trial, a multiparameter phase I trial of everolimus and sorafenib combination in solid tumors

PURPOSE

Everolimus (EVE) and sorafenib (SOR) combination was associated with synergistic activity in preclinical models. However, previous clinical studies were hampered by cumulative toxicities when both were given continuously. The academic EVESOR trial (NCT01932177) was designed to assess alternative doses and intermittent dosing schedules of EVE and SOR combination therapy to improve the benefit-risk ratio for patients with solid tumors.

METHODS

EVESOR is a multiparameter dose-escalation phase I trial investigating different doses and dosing schedules, with the final objective of generating data for modeling and simulation. Patients were allocated into continuous (A and B) or intermittent (C and D) schedules to determine the recommended phase II dose (RP2D). The clinical outcomes are presented here.

RESULTS

Forty-three patients were included from 2013 to 2019. Most of them had gynecological (25.6%), cholangiocarcinomas (23.2%), colorectal (14.0%), and breast cancers (11.6%). Dose-escalation up to EVE 10 mg QD and SOR 400 mg BID was possible on intermittent schedules. Five dose-limiting toxicities were observed, and dose reductions were required in 39.5% patients, stabilizing at EVE 5 mg and SOR 200 mg BID for 58.1% of them. The overall response rate was 6.3%, and disease control rate was 75.0%. The median progression-free survival (PFS) was 3.6 months. The longest median PFS were observed in cholangiocarcinomas (9.9 months), and gynecological adenocarcinomas (9.2 months).

CONCLUSION

Intermittent arms were associated with improved efficacy/toxicity profiles; and EVE 5 mg QD and SOR 200 mg BID was defined a clinically feasible dose. Strong signs of efficacy were found in cholangiocarcinomas and gynecologic carcinomas.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01932177.

Hereditary Endocrine Tumor Registries

Context

Endocrine neoplasia syndromes are phenotypically complex, and there is a misconception that they are universally rare. Genetic alterations are increasingly recognized; however, true prevalence is unknown. The purpose of a clinical registry is to monitor the quality of health care delivered to a specified group of patients through the collection, analysis, and reporting of relevant health-related information. This leads to improved clinical practice, decision-making, patient satisfaction, and outcome.

Objective

This review aims to identify, compare, and contrast active registries worldwide that capture data relevant to hereditary endocrine tumors (HETs).

Methods

Clinical registries were identified using a systematic approach from publications (Ovid MEDLINE, EMBASE) peer consultation, clinical trials, and web searches. Inclusion criteria were hereditary endocrine tumors, clinical registries, and English language. Exclusion criteria were institutional audits, absence of clinical data, or inactivity. Details surrounding general characteristics, funding, data fields, collection periods, and entry methods were collated.

Results

Fifteen registries specific for HET were shortlisted with 136 affiliated peer-reviewed manuscripts.

Conclusion

There are few clinical registries specific to HET. Most of these are European, and the data collected are highly variable. Further research into their effectiveness is warranted. We note the absence of an Australian registry for all HET, which would provide potential health and economic gains. This review presents a unique opportunity to harmonize registry data for HET locally and further afield.

Comprehensive Analysis of Endoplasmic Reticulum Stress in Intracranial Aneurysm

Background

Aberrant endoplasmic reticulum stress (ERS) plays an important role in multiple cardiovascular diseases. However, their implication in intracranial aneurysms (IAs) remains unclear. We designed this study to explore the general expression pattern and potential functions of ERS in IAs.

Methods

Five Gene Expression Omnibus (GEO) microarray datasets were used as the training cohorts, and 3 GEO RNA sequencing (RNA-seq) datasets were used as the validating cohorts. Differentially expressed genes (DEGs), functional enrichment, Lasso regression, logistic regression, ROC analysis, immune cell profiling, vascular smooth muscle cell (VSMC) phenotyping, weighted gene coexpression network analysis (WGCNA), and protein-protein interaction (PPI) analysis were applied to investigate the role of ERS in IA. Finally, we predicted the upstream transcription factor (TF)/miRNA and potential drugs targeting ERS.

Results

Significant DEGs were majorly associated with ERS, autophagy, and metabolism. Eight-gene ERS signature and IRE1 pathway were identified during the IA formation. WGCNA showed that ERS was highly associated with a VSMC synthesis phenotype. Next, ERS-VSMC-metabolism-autophagy PPI and ERS-TF-miRNA networks were constructed. Finally, we predicted 9 potential drugs targeting ERS in IAs.

Conclusion

ERS is involved in IA formation. Upstream and downstream regulatory networks for ERS were identified in IAs. Novel potential drugs targeting ERS were also proposed, which may delay IA formation and progress.

Advanced Adrenocortical Carcinoma: Current Perspectives on Medical Treatment

Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy. For stage I and II tumors, surgery is a curative option, but even in these cases recurrence is frequent. Practical guidelines advocate a combination of mitotane with etoposide, doxorubicin, and cisplatin as first-line therapy for metastatic adrenocortical carcinoma. However, this scheme presents limited efficacy and high toxicity. The use of Immune Checkpoint Inhibitors (ICI) and multi-Tyrosine Kinase Inhibitors (mTKI) has modified the approach of multiple malignancies. The expectation of their applicability on advanced adrenocortical carcinoma is high but the role of these new therapies persists unclear. This article provides a short summary of last years' findings targeting outcomes, limitations, and adverse effects of these new therapeutic approaches. The results of recent trials and case series pointed pembrolizumab as the most promising drug among these new therapies. It is the most often used ICI and the one presenting the best results with less related adverse effects when in comparison to the standard treatment with mitotane. Hereafter, the identification of specific molecular biomarkers or immune profiles associated with ICI or mTKI good response will facilitate the selection of candidates for these therapies. So far, microsatellite instability and Lynch Syndrome related germline mutations are suggested as predictive biomarkers of good response. Contrarywise, cortisol secretion has been associated with more aggressive ACC tumors and potentially poor responses to immunotherapy.

Plant Natural Compounds in the Treatment of Adrenocortical Tumors

Plant natural products are a plethora of diverse and complex molecules produced by the plant secondary metabolism. Among these, many can reserve beneficial or curative properties when employed to treat human diseases. Even in cancer, they can be successfully used and indeed numerous phytochemicals exert antineoplastic activity. The most common molecules derived from plants and used in the fight against cancer are polyphenols, i.e., quercetin, genistein, resveratrol, curcumin, etc. Despite valuable data especially in preclinical models on such compounds, few of them are currently used in the medical practice. Also, in adrenocortical tumors (ACT), phytochemicals are scarcely or not at all used. This work summarizes the available research on phytochemicals used against ACT and adrenocortical cancer, a very rare disease with poor prognosis and high metastatic potential, and wants to contribute to stimulate preclinical and clinical research to find new therapeutic strategies among the overabundance of biomolecules produced by the plant kingdom.

Effects of Sorafenib, a Tyrosin Kinase Inhibitor, on Adrenocortical Cancer

The lack of an effective medical treatment for adrenocortical carcinoma (ACC) has prompted the search for better treatment protocols for ACC neoplasms. Sorafenib, a tyrosine kinase inhibitor has exhibited effectiveness in the treatment of different human tumors. Therefore, the aim of this study was to understand the mechanism through which sorafenib acts on ACC, especially since treatment with sorafenib alone is sometimes unable to induce a long-lasting antiproliferative effect in this tumor type. The effects of sorafenib were tested on the ACC cell line H295R by evaluating cell viability, apoptosis and VEGF receptor signaling which was assessed by analyzing VE-cadherin and β-catenin complex formation. We also tested sorafenib on an in vitro 3D cell culture model using the same cell line. Apoptosis was observed after sorafenib treatment, and coimmunoprecipitation data suggested that the drug prevents formation VEGFR-VE-cadherin and β-catenin proteins complex. These results were confirmed both by ultrastructural analysis and by a 3D model where we observed a disaggregation of spheres into single cells, which is a crucial event that represents the first step of metastasis. Our findings suggest that although sorafenib induces apoptotic cell death a small portion of cells survive the treatment and have characteristics of a malignancy. Based on our data we recommend against the use of sorafenib in patients with ACC.

Germline EGFR variants are over-represented in adolescents and young adults (AYA) with adrenocortical carcinoma

Adrenocortical Carcinoma (ACC) is a rare endocrine tumor with poor overall prognosis and 1.5-fold overrepresentation in females. In children, ACC is associated with inherited cancer syndromes with 50-80% of childhood-ACC associated with TP53 germline variants. ACC in adolescents and young adults (AYA) is rarely due to germline TP53, IGF2, PRKAR1A and MEN1 variants. We analyzed exome sequencing data from 21 children (<15y), 32 AYA (15-39y), and 60 adults (>39y) with ACC, and retained all pathogenic, likely pathogenic, and highly prioritized variants of uncertain significance. We engineered a stable lentiviral-mutant ACC cell line, harboring an EGFR variant (p.Asp1080Asn) from a 21-year-old female without germline-TP53-variant and with aggressive ACC. We found that 4.8% of the children (P = 0.004) and 6.2% of AYA (P < 0.0001), all-female participants, harbored germline EGFR variants, compared to only 0.3% of the control group. Expanding our analysis to the RTK-RAS-MAPK pathway, we found that the RTK genes have the highest number of highly prioritized germline variants in these individuals amongst all three arms of this pathway. We showed EGFR mutant cells migrate faster and are characterized by a stem-like phenotype compared to wild type cells. While EGFR inhibitors did not affect the stemness of mutant cells, Sunitinib, a multireceptor tyrosine kinase inhibitor, significantly reduced their stem-like behavior. Our data suggest that EGFR could be a novel underlying germline predisposition factor for ACC, especially in the Childhood-AYA (C-AYA) population. Further clinical validation can improve precision oncology management of this disease, which is known to have limited therapeutic options.

Medical management of adrenocortical carcinoma: Current recommendations, new therapeutic options and future perspectives

Adrenocortical carcinoma is a rare malignant tumor of poor prognosis, frequently requiring additional treatments after initial surgery. Due to its adrenolytic action, mitotane has become the first-line medical treatment in patients with aggressive adrenocortical carcinoma. Over the last 2years, apart from the classical chemotherapy based on etoposide and platinum salts, several studies reported the use of drugs such as temozolomide, tyrosine kinase inhibitors or immunotherapy, with more or less convincing results. The aim of this review is to give further insights in the use of these drugs, and to describe potential therapeutic perspectives based on recent pangenomic studies, for the future management of these still difficult to treat tumors.

Steroidogenesis in the NCI-H295 Cell Line Model is Strongly Affected By Culture Conditions and Substrain

CONTEXT

NCI-H295 cells are the most widely used model for adrenal steroidogenesis and adrenocortical carcinoma and have been used for decades in laboratories worldwide. However, reported steroidogenic properties differ considerably.

OBJECTIVE

To evaluate heterogeneity of steroidogenesis among NCI-H295 cell strains, clarify the influence of culture media and test response to inhibitors of steroidogenesis by using liquid chromatography tandem mass spectrometry (LC-MS/MS).

METHODS

NCI-H295 cells were obtained from two cell banks and cultivated in different media. An LC-MS/MS-based panel analysis of thirteen steroids was adapted for cell culture supernatant. Cells were treated with metyrapone, abiraterone and mitotane.

RESULTS

Mineralocorticoid synthesis was strongly affected by passaging as reflected by reduction of aldosterone secretion from 0.158±0.006 to 0.017±0.001 µg/106 cells (p<0.05). Relevant differences were also found for cells from two vendors in terms of aldosterone secretion (0.180±0.001 vs. 0.09±0.002 µg/106 cells, p<0.05). Selection of medium strongly impacted on cortisol secretion with>4-fold difference (40.6±5.5 vs. 182.1±23 µg/106 cells) and reflected differential activation of the glucocorticoid pathway. Exposure to abiraterone, metyrapone and mitotane resulted in characteristic steroidogenic profiles consistent with known mechanism of drug action with considerable differences in metabolites upstream of the blocked enzyme.

CONCLUSION

We demonstrate that steroid hormone secretion in NCI-H295 cells is strongly affected by the individual strain, passage and growing conditions. These factors should be taken into account in the evaluation of experiments analyzing steroid parameters directly or as surrogate parameters of cell viability.

Past, Present and Future of Epigenetics in Adrenocortical Carcinoma

DNA methylation profiling has been suggested a reliable technique to distinguish between benign and malignant adrenocortical tumors, a process which with current diagnostic methods remains challenging and lacks diagnostic accuracy of borderline tumors. Accurate distinction between benign and malignant adrenal tumors is of the essence, since ACC is a rare but aggressive endocrine disease with an annual incidence of about 2.0 cases per million people per year. The estimated five-year overall survival rate for ACC patients is <50%. However, available treatment regimens are limited, in which a radical surgical resection is the only curable option. Nevertheless, up to 85% of patients with radical resection show recurrence of the local disease often with concurrent metastases. Adrenolytic therapy with mitotane, administered alone or in combination with cytotoxic agents, is currently the primary (palliative) treatment for patients with advanced ACC and is increasingly used in adjuvant setting to prevent recurrence. Prognostic stratification is important in order to individualize adjuvant therapies. On April 1, 2020, there were 7404 publications on adrenocortical carcinoma (adrenocortical carcinoma) OR adrenocortical carcinoma [MeSH Terms]) OR adrenal cortex cancer[MeSH Terms]) OR adrenal cortical carcinoma [MeSH Terms]) OR adrenal cortex neoplasm [MeSH Terms]) OR adrenocortical cancer [MeSH Terms]), yet the underlying pathophysiology and characteristics of ACC is not fully understood. Knowledge on epigenetic alterations in the process of adrenal tumorigenesis is rapidly increasing and will add to a better understanding of the pathogenesis of ACC. DNA methylation profiling has been heralded as a promising method in the prognostication of ACC. This review summarizes recent findings on epigenetics of ACC and its role in diagnosis, prognosis and therapeutic strategies.

Objective Response and Prolonged Disease Control of Advanced Adrenocortical Carcinoma with Cabozantinib

BACKGROUND

Objective response of advanced adrenocortical carcinoma (ACC) to mitotane and cytotoxic chemotherapy regimen is only ~20% and early tumor progression is frequent. Previous clinical trials with oral multikinase inhibitors were negative, which has been attributed in part to inadvertent drug interaction with mitotane. Cabozantinib (CABO) is an inhibitor of c-MET, vascular endothelial growth factor receptor 2, AXL, and RET and approved for advanced kidney cancer, liver carcinoma after previous sorafenib, and medullary thyroid carcinoma.

OBJECTIVE

To investigate the clinical efficacy and safety of CABO monotherapy in ACC patients.

DESIGN

Retrospective cohort study.

SETTING

Three referral centers for ACC (Germany, United States).

RESULTS

Sixteen patients (13 female) with progressive ACC received CABO after previous mitotane in 15/16 and 3 (median, range 0-8) further systemic treatments. Prior CABO therapy, mitotane was discontinued in all patients. Mitotane plasma concentration was <2 mg/L in 7/16 patients and discontinued >12 months in 6 additional patients before CABO use. In 4/5 cases with available plasma samples, CABO concentration was in the expected steady-state range. Adverse events of grade 1/2 and 3 were observed in 13 and 3 patients, respectively, and consistent with the known safety profile of CABO. Best response was partial response in 3, stable disease in 5, and progressive disease in 8 patients. Median progression-free and overall survival was 16 and 58 weeks, respectively.

CONCLUSION

CABO monotherapy appears to be safe and effective as a monotherapy in advanced ACC after failing prior treatments. Therefore, prospective investigation of CABO in ACC patients is warranted.

Next-generation therapies for adrenocortical carcinoma

Almost one decade ago, etoposide, doxorubicin, cisplatin and mitotane (EDP-M) has been established as first-line systemic therapy of metastatic adrenocortical carcinoma (ACC). Although heterogeneous, the prognosis of advanced stage ACC is still poor and novel treatments are urgently needed. This article provides a short summary of current systemic ACC treatment and provides a comprehensive overview of new therapeutic approaches that have been investigated in the past years, including drugs targeting the IGF pathway, tyrosine kinase inhibitors, radionuclide treatment, and immunotherapy. The results of most of these trials were disappointing and we will discuss possible reasons why these drugs failed (e.g. drug interactions with mitotane, disease heterogeneity with exceptional responses in very few patients, and resistance mechanisms to immunotherapy). We then will present potential new drug targets that have emerged from many molecular studies (e.g. wnt/β-catenin, cyclin-dependent kinases, PARP1) that may be the foundation of next-generation therapies of ACC.

Anticancer Effects of Wild Mountain Mentha longifolia Extract in Adrenocortical Tumor Cell Models

Mint [Mentha longifolia (L.) Hudson] is an aromatic plant that belongs to Lamiaceae family. It is traditionally used as herbal tea in Europe, Australia and North Africa and shows numerous pharmacological effects, such as spasmolytic, antioxidant, antimicrobial and anti-hemolytic. Recently, its antiproliferative role has been suggested in a small number of tumor cell models, but no data are available on adrenocortical carcinoma, a malignancy with a survival rate at 5 years of 20%-30% which frequently metastasize. This work aimed to study the effects of Mentha longifolia L. crude extract (ME) on two adrenocortical tumor cell models (H295R and SW13 cells). Chemical composition of ME was assessed by gas-chromatography/mass spectrometry and NMR spectroscopy analysis. Brine shrimp lethality assay showed ME effects at >0.5 µg/µl (p < 0.05). Cell viability and vitality were determined by MTT, SRB, and trypan blue assays in H295R and SW13 cells. The anti-proliferative effects of ME were more evident in SW13 cells at 72 h (ME > 0.5 µg/µl, p < 0.05). Combination of ME with mitotane (approved drug for adrenocortical carcinoma) seemed not to reinforce the efficacy of the herb. As control, human fibroblasts were treated with ME with no effect on cell viability. Clonogenic assay was concordant with previous cell viability tests (ME > 0.5 µg/µl, p < 0.05), while Wright staining demonstrated the presence of both necrotic and apoptotic cells. Cell cycle analysis showed a strong increase in subG0/G1 phase, related to cell death. Furthermore, MAPK and PI3k/Akt pathways were modulated by Western blot analysis when treating cells with ME alone or combined with mitotane. The crude methanolic extract of wild mountain mint can decrease cell viability, vitality and survival of adrenocortical tumor cell models, in particular of SW13 cells. These data show the potential anticancer effects of ME, still more work is needed to corroborate these findings.

Proteomic Landscape of Aldosterone-Producing Adenoma

Primary aldosteronism is a disease of excessive production of adrenal steroid hormones and the most common cause of endocrine hypertension. Primary aldosteronism results mainly from bilateral adrenal hyperplasia or unilateral aldosterone-producing adenoma (APA). Primary aldosteronism cause at the molecular level is incompletely understood and a targeted treatment preventing excessive adrenal steroid production is not available. Here, we perform deep quantitative proteomic and phosphoproteomic profiling of 6 pairs of APA and adjacent nontumoral adrenal cortex. We show that increased steroidogenesis in APA is accompanied by upregulation of steroidogenic enzymes (HSD3B2, CYP21A2, CYP11B2) and of proteins involved in cholesterol uptake (LSR). We demonstrate that HSD3B2 is phosphorylated at Ser95 or 96 and identify a novel phosphorylation site, Ser489, in CYP21A2, suggesting that steroidogenic enzymes are regulated by phosphorylation. Our analysis also reveals altered ECM (extracellular matrix) composition in APA that affects ECM-cell surface interactions and actin cytoskeleton rearrangements. We show that RHOC, a GTPase controlling actin organization in response to extracellular stimuli, is upregulated in APA and promotes expression of the aldosterone synthase gene CYP11B2. Our data also indicate deregulation of protein N-glycosylation and GABAergic signaling in APAs. Finally, we find that mTORC1 (mammalian target of rapamycin complex 1) signaling is the major pathway deregulated in APA. Our study provides a rich resource for future research on the molecular mechanisms of primary aldosteronism.

Treatment of Primary Aldosteronism With mTORC1 Inhibitors

CONTEXT

Mammalian target of rapamycin complex 1 (mTORC1) activity is often increased in the adrenal cortex of patients with primary aldosteronism (PA), and mTORC1 inhibition decreases aldosterone production in adrenocortical cells, suggesting the mTORC1 pathway as a target for treatment of PA.

OBJECTIVE

To investigate the effect of mTORC1 inhibition on adrenal steroid hormones and hemodynamic parameters in mice and in patients with PA.

DESIGN

(i) Plasma aldosterone, corticosterone, and angiotensin II (Ang II) were measured in mice treated for 24 hours with vehicle or rapamycin. (ii) Plasma aldosterone levels after a saline infusion test, plasma renin, and 24-hour urine steroid hormone metabolome and hemodynamic parameters were measured during an open-label study in 12 patients with PA, before and after 2 weeks of treatment with everolimus and after a 2-week washout.

MAIN OUTCOME MEASURES

(i) Change in plasma aldosterone levels. (ii) Change in other steroid hormones, renin, Ang II, and hemodynamic parameters.

RESULTS

Treatment of mice with rapamycin significantly decreased plasma aldosterone levels (P = 0.007). Overall, treatment of PA patients with everolimus significantly decreased blood pressure (P < 0.05) and increased renin levels (P = 0.001) but did not decrease aldosterone levels significantly. However, prominent reduction of aldosterone levels upon everolimus treatment was observed in four patients.

CONCLUSION

In mice, mTORC1 inhibition was associated with reduced plasma aldosterone levels. In patients with PA, mTORC1 inhibition was associated with improved blood pressure and renin suppression. In addition, mTORC1 inhibition appeared to reduce plasma aldosterone in a subset of patients.

The role of mTOR pathway as target for treatment in adrenocortical cancer

Adrenocortical carcinomas (ACCs) are rare tumors with scant treatment options for which new treatments are required. The mTOR pathway mediates the intracellular signals of several growth factors, including the insulin-like growth factors (IGFs), and therefore represents a potential attractive pathway for the treatment of several malignancies including ACCs. Several mTOR inhibitors, including sirolimus, temsirolimus and everolimus, have been clinically developed. This review summarizes the results of the studies evaluating the expression of the mTOR pathway components in ACCs, the effects of the mTOR inhibitors alone or in combination with other drugs in preclinical models of ACCs and the early experience with the use of these compounds in the clinical setting. The mTOR pathway seems a potential target for treatment of patients with ACC, but further investigation is still required to define the potential role of mTOR inhibitors alone or in combination with other drugs in the treatment of ACC patients.

Biological Effects of EF24, a Curcumin Derivative, Alone or Combined with Mitotane in Adrenocortical Tumor Cell Lines

BACKGROUND

Curcumin has numerous properties and is used in many preclinical conditions, including cancer. It has low bioavailability, while its derivative EF24 shows enhanced solubility. However, its effects have never been explored in adrenocortical tumor cell models. The efficacy of EF24 alone or combined with mitotane (reference drug for adrenocortical cancer) was evaluated in two adrenocortical tumor cell lines, SW13 and H295R.

METHOD AND RESULTS

EF24 reduced cell viability with an IC50 (half maximal inhibitory concentration) of 6.5 ± 2.4 μM and 4.9 ± 2.8 μM for SW13 and H295R cells, respectively. Combination index (EF24 associated with mitotane) suggested an additivity effect in both cell lines. Cell cycle analysis revealed an increase in subG0/G1 phase, while motility assay showed a decrease in migratory cell capacity, and similarly, clonogenic assay indicated that EF24 could reduce colony numbers. Furthermore, Wnt/β-catenin, NF-κB, MAPK, and PI3k/Akt pathways were modulated by Western blot analysis when treating cells with EF24 alone or combined with mitotane. In addition, intracellular reactive oxygen species levels increased in both cell lines.

CONCLUSION

This work analyzed EF24 in adrenocortical tumor cell lines for the first time. These results suggest that EF24 could potentially impact on adrenocortical tumors, laying the foundation for further research in animal models.

Mouse models in endocrine tumors

Endocrine and neuroendocrine tumors comprise a highly heterogeneous group of neoplasms that can arise from (neuro)endocrine cells, either from endocrine glands or from the widespread diffuse neuroendocrine system, and, consequently, are widely distributed throughout the body. Due to their diversity, heterogeneity and limited incidence, studying in detail the molecular and genetic alterations that underlie their development and progression is still a highly elusive task. This, in turn, hinders the discovery of novel therapeutic options for these tumors. To circumvent these limitations, numerous mouse models of endocrine and neuroendocrine tumors have been developed, characterized and used in pre-clinical, co-clinical (implemented in mouse models and patients simultaneously) and post-clinical studies, for they represent powerful and necessary tools in basic and translational tumor biology research. Indeed, different in vivo mouse models, including cell line-based xenografts (CDXs), patient-derived xenografts (PDXs) and genetically engineered mouse models (GEMs), have been used to delineate the development, progression and behavior of human tumors. Results gained with these in vivo models have facilitated the clinical application in patients of diverse breakthrough discoveries made in this field. Herein, we review the generation, characterization and translatability of the most prominent mouse models of endocrine and neuroendocrine tumors reported to date, as well as the most relevant clinical implications obtained for each endocrine and neuroendocrine tumor type.

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.

The tyrosine kinase inhibitor nilotinib is more efficient than mitotane in decreasing cell viability in spheroids prepared from adrenocortical carcinoma cells

Background

New drugs for adrenocortical carcinoma (ACC) are needed because most patients undergo rapid disease progression despite surgery and adjuvant therapy with mitotane. In this study, we aimed to investigate the in vitro effects of different chemotherapy drugs, alone or combined with mitotane, on the viability of adrenocortical carcinoma cells.

Methods

Everolimus, sunitinib, zoledronic acid, imatinib and nilotinib cytotoxicity, alone or combined with mitotane were tested on ACC H295R cells in monolayer or spheroid cultures using MTS assays and confocal microscopy. Moreover, the nilotinib effects were investigated in spheroids cultured from patient tumor-derived ACC-T36 cells.

Results

Morphological characterization of H295R cell spheroids using histochemistry was performed and showed that dense, homogenously sized, multicellular spheroids were obtained. We observed that sunitinib and nilotinib alone were equally effective in a monolayer preparation, whereas mitotane was the most effective even at a low dose. A combination of sunitinib and mitotane was the most effective treatment, with only 23.8% of cells in the monolayer remaining viable. Spheroid preparations showed resistance to different drugs, although the poor effect produced by mitotane alone was surprising, with a cell viability of 84.6% in comparison with 13.1% in monolayer cells. The most ineffective drugs in spheroid preparations were everolimus, zoledronic acid and imatinib. In both cell types, nilotinib, either alone or in combination with mitotane induced more significant cell viability inhibition in monolayer and spheroid preparations. In addition, the mechanism of nilotinib activity involves the ERK1/2 pathway.

Conclusion

Taken together, our data identified nilotinib as a cytotoxic drug that combined with ERK inhibitors deserves to be tested as a novel therapy for adrenocortical carcinoma.

Crude extract of Origanum vulgare L. induced cell death and suppressed MAPK and PI3/Akt signaling pathways in SW13 and H295R cell lines

Oregano (Origanum vulgare L.) is a common aromatic plant used in Mediterranean and Asian Regions for treating respiratory diseases, painful menstruation, rheumatoid arthritis, etc. Recently its role as an anticancer plant has been suggested, although oregano has been never evaluated into adrenocortical tumour cell models. This study analysed for the first time the anticancer effects of a crude extract of wild mountain oregano (Origanum vulgare L.) in SW13 and H295R cell lines. The crude extract was characterised by GC/MS and the toxic effects of oregano were first analysed by brine shrimp lethality assay. Our findings demonstrated that oregano decreased cell viability, survival, modified cell cycle and induced cell death (through necrotic process) and that the effects can be attributed to a blockade of MAPK and PI3 K/Akt pathways. These results suggest that oregano extract exerts anticancer activities in adrenocortical tumour cell lines, providing evidence for further research in higher models.

Co-inhibition of EGFR and IGF1R synergistically impacts therapeutically on adrenocortical carcinoma

Purpose

Adrenocortical carcinoma (ACC) is a rare tumor with very poor prognosis and no effective treatment. The aim of this study was to explore a novel therapy co-targeting EGFR and IGF1R in vitro and vivo.

Methods

The expression of EGFR and IGF1R were evaluated in a series of adrenocortical tumors by immunohistochemistry. Cell viability of ACC cell lines H295R and SW13 were determined by MTT assay after treatment with the combination of EGFR inhibitor Erlotinib and IGF1R inhibitor NVP-AEW541. Apoptosis was assessed by flow cytometry. The mechanism within intracellular signaling pathways was analyzed by Western blot. Mice bearing human ACC xenografts were treated with Erlotinib and NVP-AEW541, and the effects on tumour growth were assessed.

Results

Our results show a significant over-expression of EGFR (66.67%) and IGF1R (80.0%) in ACC. Besides, the co-overexpression of EGFR and IGF1R was seen in 8/15 ACCs, as compared with ACAs (P<0.05). Erlotinib and NVP-AEW541 significantly inhibited cell viability and induced apoptosis by blocking phosphorylation of MEK/ERK and AKT, respectively. Meanwhile, we found that single inhibition of IGF1R induced compensatory activation of MEK/ERK, leading to sustained activation of mTOR, which represent as aggregation of EGFR and IGF1R downstream components. More importantly, the combination of Erlotinib and NVP-AEW541 enhances anti-tumour efficacy compared to treatment with either agent alone or to untreated control in vitro and vivo.

Conclusions

In conclusion, coinhibition therapy targeting EGFR and IGF1R may be considerable for treatment of ACC in the future.

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.

Tissue Expression and Pharmacological In Vitro Analyses of mTOR and SSTR Pathways in Adrenocortical Carcinoma

New therapies for advanced adrenocortical carcinoma (ACC) are urgently needed, as the majority of the patients experience a rapid and inexorable progression despite surgery and adjuvant mitotane. In vitro data suggest that somatostatin receptors (SSTRs) and mTOR pathway might represent reasonable targets for novel therapies, being involved in functionality and growth of ACC cells. However, in vitro analysis of combination treatments targeting both mTOR and SSTR as compared to mitotane are poorly explored in ACC. This study aimed to investigate in vitro the effects on cell growth of pasireotide, everolimus, and mitotane, alone or combined, in the two ACC cell lines H295R and SW13 (mitotane sensitive and resistant, respectively). Moreover, the tissue expression of mTOR pathway molecules and SSTR (types 1-5) was assessed in 58 ACCs. In both cell lines, only everolimus induced a significant inhibition of cell growth. Conversely, the combinations among mitotane, pasireotide, and everolimus produced antagonistic effects on mitotane-induced growth inhibition on H295R cell line. A heterogeneous profile of mTOR-related molecules and SSTR expression was observed in ACC samples, being the mTOR pathway found activated in approximately 30% of cases. In conclusion, our data suggest caution in designing combinations of mitotane with other drugs potentially active in ACC, such as mTOR inhibitors or somatostatin analogs.

Update on adrenocortical carcinoma management and future directions

PURPOSE OF REVIEW

To present an update on the management of and future directions in adrenocortical carcinoma (ACC).

RECENT FINDINGS

ACC is a rare malignancy with high morbidity and mortality. Surgery remains the mainstay treatment for localized disease, but it is often not feasible in more advanced cases. There is an ongoing controversy about the routine use of adjuvant treatments after surgery. Hormonal overproduction can complicate the management and worsen the prognosis of the disease. Systemic therapy with multiple cytotoxic drugs is often combined with the adrenolytic agent mitotane. Genomic analyses of ACC revealed numerous signal transduction pathway aberrations (insulin-like growth factor 2 overexpression, TP53 mutations and Wnt/β-catenin pathway activation), but so far, there has been no clinically meaningful breakthrough in targeting these genes. Immunotherapy offers hope for altering the orthodox management of cancer, and its role in ACC is being explored in multiple ongoing trials.

SUMMARY

Surgery by experienced team is the key treatment for localized ACC, whereas currently used chemotherapy has limited efficacy in advanced ACC. The improved understanding of the molecular pathways involved in ACC has not been translated into effective therapy. The development of new therapies requires collaborative effort to fight this disease.

Investigation of N-cadherin/β-catenin expression in adrenocortical tumors

β-catenin is a multifunctional protein; it is a key component of the Wnt signaling, and it plays a central role in cadherin-based adhesions. Cadherin loss promotes tumorigenesis by releasing membrane-bound β-catenin, hence stimulating Wnt signaling. Cadherins seem to be involved in tumor development, but these findings are limited in adrenocortical tumors (ACTs). The objective of this study was to evaluate alterations in key components of cadherin/catenin adhesion system and of Wnt pathway. This study included eight normal adrenal samples (NA) and 95 ACT: 24 adrenocortical carcinomas (ACCs) and 71 adrenocortical adenomas (ACAs). β-catenin mutations were evaluated by sequencing, and β-catenin and cadherin (E-cadherin and N-cadherin) expression was analyzed by quantitative reverse transcription PCR (qRT-PCR) and by immunohistochemistry (IHC). We identified 18 genetic alterations in β-catenin gene. qRT-PCR showed overexpression of β-catenin in 50 % of ACC (12/24) and in 48 % of ACA (21/44). IHC data were in accordance with qRT-PCR results: 47 % of ACC (7/15) and 33 % of ACA (11/33) showed increased cytoplasmic or nuclear β-catenin accumulation. N-cadherin downregulation has been found in 83 % of ACC (20/24) and in 59 % of ACA (26/44). Similar results were obtained by IHC: N-cadherin downregulation was observed in 100 % (15/15) of ACC and in 55 % (18/33) of ACA. β-catenin overexpression together with the aberrant expression of N-cadherin may play important role in ACT tumorigenesis. The study of differentially expressed genes (such as N-cadherin and β-catenin) may enhance our understanding of the biology of ACT and may contribute to the discovery of new diagnostic and prognostic tools.

Overexpression of L-Type Amino Acid Transporter 1 (LAT1) and 2 (LAT2): Novel Markers of Neuroendocrine Tumors

Background

6-18F-fluoro-L-3,4-dihydroxyphenylalanine (¹⁸F-FDOPA) PET is a useful tool in the clinical management of pheochromocytoma (PHEO) and medullary thyroid carcinoma (MTC). ¹⁸F-FDOPA is a large neutral amino acid biochemically resembling endogenous L-DOPA and taken up by the L-type amino acid transporters (LAT1 and LAT2). This study was conducted to examine the expression of the LAT system in PHEO and MTC.

Methods

Real-time PCR and Western blot analyses were used to assess LAT1 and LAT2 gene and protein expression in 32 PHEO, 38 MTC, 16 normal adrenal medulla and 15 normal thyroid tissue samples. Immunohistochemistry method was applied to identify the proteins’ subcellular localization.

Results

LAT1 and LAT2 were overexpressed in both PHEO and MTC by comparison with normal tissues. LAT1 presented a stronger induction than LAT2, and their greater expression was more evident in PHEO (15.1- and 4.1-fold increases, respectively) than in MTC (9.9- and 4.1-fold increases, respectively). Furthermore we found a good correlation between LAT1/2 and GLUT1 expression levels. A positive correlation was also found between urinary noradrenaline and adrenaline levels and LAT1 gene expression in PHEO. The increased expression of LAT1 is also confirmed at the protein level, in both PHEO and MTC, with a strong cytoplasmic localization.

Conclusions

The present study is the first to provide experimental evidence of the overexpression in some NET cancers (such as PHEO or MTC) of L-type amino acid transporters, and the LAT1 isoform in particular, giving the molecular basis to explain the increase of the DOPA uptake seen in such tumor cells.

Xenograft models for adrenocortical carcinoma

Adrenocortical carcinomas (ACCs) are rare, heterogeneous and very malignant endocrine tumors with a poor prognosis. An important prerequisite to optimize existing therapeutic regimens and to develop novel therapeutic strategies are preclinical disease models. In recent years molecular and genetic profiling of surgical tumor specimen led to the identification of novel interesting markers. However, precise involvement of these markers in tumorigenesis and their functional relevance in therapeutic outcome is still under investigation. Xenograft models are important tools for such functional studies as they bear the potential to mimic the complexity of solid tumors including tumor cells, stroma and blood vessels. Thus, for the successful and safe development of novel therapeutic strategies xenograft models remain to be indispensable experimental tools. Here we provide an overview on currently existing xenograft models for ACC, their tissue origins, establishment, implications as well as limitations.

Hepatocyte Growth Factor/cMET Pathway Activation Enhances Cancer Hallmarks in Adrenocortical Carcinoma

Adrenocortical carcinoma is a rare malignancy with poor prognosis and limited response to chemotherapy. Hepatocyte growth factor (HGF) and its receptor cMET augment cancer growth and resistance to chemotherapy, but their role in adrenocortical carcinoma has not been examined. In this study, we investigated the association between HGF/cMET expression and cancer hallmarks of adrenocortical carcinoma. Transcriptomic and immunohistochemical analyses indicated that increased HGF/cMET expression in human adrenocortical carcinoma samples was positively associated with cancer-related biologic processes, including proliferation and angiogenesis, and negatively correlated with apoptosis. Accordingly, treatment of adrenocortical carcinoma cells with exogenous HGF resulted in increased cell proliferation in vitro and in vivo while short hairpin RNA-mediated knockdown or pharmacologic inhibition of cMET suppressed cell proliferation and tumor growth. Moreover, exposure of cells to mitotane, cisplatin, or radiation rapidly induced pro-cMET expression and was associated with an enrichment of genes (e.g., CYP450 family) related to therapy resistance, further implicating cMET in the anticancer drug response. Together, these data suggest an important role for HGF/cMET signaling in adrenocortical carcinoma growth and resistance to commonly used treatments. Targeting cMET, alone or in combination with other drugs, could provide a breakthrough in the management of this aggressive cancer.

The challenge of managing adrenocortical carcinoma: two case studies

Adrenocortical carcinoma is a rare entity affecting 1–2 people per million. It has a relatively poor prognosis, with an overall 5-year survival of 20–45%. The reasons include a high risk of recurrence following resection and relatively poor response to cytotoxic treatment. The use of the adrenalytic mitotane as adjuvant therapy is supported by level III evidence from cohort studies. In the metastatic setting, one randomized controlled trial provides level II evidence for a three-drug chemotherapy combination of cisplatin, etoposide and doxorubicin, with mitotane (EDP–M). We present two cases of adrenocortical carcinoma and discuss their management in light of the literature supporting the treatments. These cases illustrate the practicalities of management requiring a multidisciplinary team with the oncologist, endocrinologist, surgeon, anesthetist, radiologist and pathologist, all working in collaboration.

Evaluation of in vivo responses of sorafenib therapy in a preclinical mouse model of PTEN-deficient of prostate cancer

Background

Despite recent advances in the treatment for advanced prostate cancer, outcomes remain poor. This lack of efficacy has prompted the development of alternative treatment strategies. In the present study we investigate the effects of the multikinase inhibitor sorafenib in a genetically engineered mouse model of prostate cancer and explore the rational combination with the mTOR inhibitor everolimus.

Methods

Conditional prostate specific PTEN-deficient knockout mice were utilized to determine the pharmacodynamic and chemopreventive effects of sorafenib. This mouse model was also used to examine the therapeutic efficacy of sorafenib alone or in combination with everolimus. Preclinical efficacy was assessed by comparing the reduction of tumor burden, proliferation, angiogenesis and the induction of apoptosis. Molecular responses were assessed by immunohistochemical, TUNEL and western blot assays.

Results

Pharmacodynamic analysis revealed that a single dose of sorafenib decreased activation of the PI3K/AKT/mTOR signaling axis at doses of 30–60 mg/kg, but activated JAK/STAT3 signaling. Levels of cleaved casapase-3 increased in a dose dependent manner. Chemoprevention studies showed that chronic sorafenib administration was capable of inhibiting tumor progression through the reduction of cancer cell proliferation, angiogenesis and the induction of apoptosis. In intervention models of established castration-naïve and castration-resistant prostate cancer, treatment with sorafenib provided modest but statistically insignificant reduction in tumor burden. However, sorafenib significantly inhibited cancer cell proliferation and MVD but had minimal effects on the induction of apoptosis. Interestingly, the administration of sorafenib increased the expression levels of the androgen receptor, p-GSK3β and p-ERK1/2 in castration-resistant prostate cancers. In both intervention models, combination therapy demonstrated a clear tendency of enhanced antitumor effects over monotherapy. Notably, the treatment combination of sorafenib and everolimus overcame therapeutic escape from single agent therapy in castration-resistant prostate cancers.

Conclusions

In summary, we provide insights into the molecular responses of sorafenib therapy in a clinically relevant model of prostate cancer and present preclinical evidence for the development of targeted treatment strategies based on the use of multikinase inhibitors in combination with mTOR inhibitors for the treatment of advanced prostate cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-015-0509-x) contains supplementary material, which is available to authorized users.

The miR-199a/Brm/EGR1 axis is a determinant of anchorage-independent growth in epithelial tumor cell lines

In epithelial cells, miRNA-199a-5p/-3p and Brm, a catalytic subunit of the SWI/SNF complex were previously shown to form a double-negative feedback loop through EGR1, by which human cancer cell lines tend to fall into either of the steady states, types 1 [miR-199a(−)/Brm(+)/EGR1(−)] and 2 [miR-199a(+)/Brm (−)/EGR1(+)]. We show here, that type 2 cells, unlike type 1, failed to form colonies in soft agar, and that CD44, MET, CAV1 and CAV2 (miR-199a targets), all of which function as plasma membrane sensors and can co-localize in caveolae, are expressed specifically in type 1 cells. Single knockdown of any of them suppressed anchorage-independent growth of type 1 cells, indicating that the miR-199a/Brm/EGR1 axis is a determinant of anchorage-independent growth. Importantly, two coherent feedforward loops are integrated into this axis, supporting the robustness of type 1-specific gene expression and exemplifying how the miRNA-target gene relationship can be stably sustained in a variety of epithelial tumors.

The PI3K/Akt Pathway in Tumors of Endocrine Tissues

The phosphatidylinositol 3-kinase (PI3K)/Akt pathway is a key driver in carcinogenesis. Defects in this pathway in human cancer syndromes such as Cowden's disease and Multiple Endocrine Neoplasia result in tumors of endocrine tissues, highlighting its importance in these cancer types. This review explores the growing evidence from multiple animal and in vitro models and from analysis of human tumors for the involvement of this pathway in the following: thyroid carcinoma subtypes, parathyroid carcinoma, pituitary tumors, adrenocortical carcinoma, phaeochromocytoma, neuroblastoma, and gastroenteropancreatic neuroendocrine tumors. While data are not always consistent, immunohistochemistry performed on human tumor tissue has been used alongside other techniques to demonstrate Akt overactivation. We review active Akt as a potential prognostic marker and the PI3K pathway as a therapeutic target in endocrine neoplasia.

EJE prize 2014: current and evolving treatment options in adrenocortical carcinoma: where do we stand and where do we want to go?

Adrenocortical carcinoma (ACC) is not only a rare and heterogeneous disease but also one of the most aggressive endocrine tumors. Despite significant advances in the last decade, its pathogenesis is still only incompletely understood and overall therapeutic means are unsatisfactory. Herein, we provide our personal view of the currently available treatment options and suggest the following research efforts that we consider timely and necessary to improve therapy: i) for better outcome in localized ACCs, surgery should be restricted to experienced centers, which should then collaborate closely to address the key surgical questions (e.g. best approach and extent of surgery) in a multicenter manner. ii) For the development of better systemic therapies, it is crucial to elucidate the exact molecular mechanisms of action of mitotane. iii) A prospective trial is needed to address the role of cytotoxic drugs in the adjuvant setting in aggressive ACCs (e.g. mitotane vs mitotane+cisplatin). iv) For metastatic ACCs, new regimens should be investigated as first-line therapy. v) Several other issues (e.g. the role of radiotherapy and salvage therapies) might be answered - at least in a first step - by large retrospective multicenter studies. In conclusion, although it is unrealistic to expect that the majority of ACCs can be cured within the next decade, international collaborative efforts (including multiple translational and clinical studies) should allow significant improvement of clinical outcome of this disease. To this end, it might be reasonable to expand the European Network for the Study of Adrenal Tumors (ENSAT) to a truly worldwide international network - INSAT.

The combination of RAF265, SB590885, ZSTK474 on thyroid cancer cell lines deeply impact on proliferation and MAPK and PI3K/Akt signaling pathways

Papillary thyroid cancer (PTC) is the most frequent thyroid cancer entity, accounting for 88 % of cases. It may metastasize and loose iodine uptake capability, preventing any radioiodine or surgical treatment. The main gene altered in PTC is BRAF, which is found altered in over 50 % of cases. Moreover MAPK and PI3K/Akt pathways are greatly implicated in PTC development. Many target therapies for PTC are currently under investigation, unfortunately without the expected results. Aim of this study was to characterized the preclinical effectiveness of novel promising drugs, RAF265, SB590885 and ZSTK474 in 3 thyroid cancer cell lines (BCPAP, K1, 8505C). RAF265 and SB590885 target differentially BRAF, while ZSTK474 acts on PI3K. IC50 demonstrated high drug activities ranging from 0.1 to 6.2 μM, depending on drugs and cell type, while combination index revealed an interesting synergistic effect of combination regimen (RAF265 + ZSTK474 and SB590885 + ZSTK474) in almost all cell lines. Moreover this synergistic effect was particularly evident by Western blot, whereas dual MAPK and PI3K/Akt inhibition was detected. In addition, treating cells with SB590885 induced marked morphological changes, leading to massive vacuolization. This suggests an activation of apoptotic process, as underlined by Annexin V flow cytometry analysis. Also cell cycle was altered in treated cells, without evidence of a common pattern, but rather with a more specific effect relying on single drug or combination regimen used. Since beneficial effects of in vitro combination regimen (RAF265 + ZSTK474 and SB590885 + ZSTK474), it is recommended additional investigation. These data suggest the potential use of combination regimen in in vivo experiment or afterwards in human PTC.

Prevalence, tumorigenic role, and biochemical implications of rare BRAF alterations

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most common malignant tumor of the thyroid gland, accounting for 74-80% of all thyroid cancers. The 1799T>A transversion is an activating mutation of the BRAF oncogene that is common in and specific to conventional PTC. We studied the prevalence, tumorigenic role, and biochemical implications of rare BRAF variants in a large cohort of patients.

METHODS

A total of 2131 fine-needle aspiration biopsy samples were collected and subjected to BRAF mutation analysis. BRAF genetic variants were analyzed by Western blot, immunofluorescence, and in silico analysis.

RESULTS

BRAF mutations were found in 50% (347/700) of thyroid cancers (644 PTCs, 22 anaplastic thyroid carcinomas, 34 follicular thyroid carcinomas). They were the classic (c.1799T>A, p.V600E) mutation in 96.8% (336/347) and rare genetic variants in 3.2% (11/347). In all, five infrequent BRAF alterations were detected: (i) c.1795_1797dupACA (p.T599dup); (ii) c.1801A>G (p.K601E); (iii) c.1799_1801delTGA (p.V600_K601>E); (iv) c.1799_1814>A (p.V600_S605>D); and (v) c.1798_1810delinsA (p.V600_W604>R). The last BRAF variant has never been described in the literature. Western blot analysis and immunofluorescence both revealed a variegated reactivity pattern, again emphasizing the peculiar role of every specific BRAF genetic alteration. In silico analysis of the samples studied revealed a stabilization of the "active" geometrical conformation of the B-raf enzyme associated with the activated and productive state of the kinase domain.

CONCLUSIONS

Rare BRAF variants were found in 1.6% of all thyroid malignancies, all clustered around the codon V600, in the binding pocket named A-loop, confirming its crucial role in the enzymatic activation of the B-Raf protein. These mutations were associated mainly with the activation of key effectors in the mitogen-activated protein kinase pathway, but a simultaneous stimulation of the PI3k/Akt cascade was demonstrated in some cases. The rare BRAF variants were not generally associated with an aggressive behavior of the PTC. To our knowledge, this is the largest series of thyroid cancers analyzed to identify and functionally characterize rare BRAF variants.

Genetics and epigenetics of adrenocortical tumors

Adrenocortical tumors are common neoplasms. Most are benign, nonfunctional and clinically irrelevant. However, adrenocortical carcinoma is a rare disease with a dismal prognosis and no effective treatment apart from surgical resection. The molecular genetics of adrenocortical tumors remain poorly understood. For decades, molecular studies relied on a small number of samples and were directed to candidate-genes. This approach, based on the elucidation of the genetics of rare genetic syndromes in which adrenocortical tumors are a manifestation, has led to the discovery of major dysfunctional molecular pathways in adrenocortical tumors, such as the IGF pathway, the Wnt pathway and TP53. However, with the advent of high-throughput methodologies and the organization of international consortiums to obtain a larger number of samples and high-quality clinical data, this paradigm is rapidly changing. In the last decade, genome-wide expression profile studies, microRNA profiling and methylation profiling allowed the identification of subgroups of tumors with distinct genetic markers, molecular pathways activation patterns and clinical behavior. As a consequence, molecular classification of tumors has proven to be superior to traditional histological and clinical methods in prognosis prediction. In addition, this knowledge has also allowed the proposal of molecular-targeted approaches to provide better treatment options for advanced disease. This review aims to summarize the most relevant data on the rapidly evolving field of genetics of adrenal disorders.

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.

The antiproliferative effects of ouabain and everolimus on adrenocortical tumor cells

Ouabain is a cardiotonic steroid obtained from Strophanthus. Recently its role as antiproliferative agent has been investigated in tumor cells. Everolimus is a derivative of rapamycin and acts as a signal transduction inhibitor. Adrenocortical carcinoma is a rare cancer, with poor prognosis. This research focuses on antineoplastic properties of ouabain and its association with everolimus. We analyzed the effects of drugs on cells by MTT assay, by [(3)H] thymidine assay, by Wright's staining, by homogeneous caspases assay, by flow cytometry analysis and by Western blot analysis on H295R and SW13 cells and on primary adrenocortical tumor cells. Ouabain induced cell viability reduction in SW13, H295R and 5 primary adrenocortical tumor cells. Combination of ouabain with everolimus produced a stronger cytotoxic effect on cell proliferation and viability. Marked morphological changes were observed in both SW13 and H295R cell lines after ouabain treatment, with an increase in necrosis. Cell cycle distribution was altered by ouabain in SW13. Analysis of apoptosis demonstrated an increase in caspase activity, clearly evident for SW13 at 72h. FACS analysis by Annexin V-FITC kit and propidium iodide confirmed an increased level of necrosis at higher concentrations. Western blot analysis showed that PI3k/Akt signaling pathway was modified after ouabain treatments in SW13. Ouabain exerts antiproliferative effects on SW13 and H295R cell lines and on primary adrenocortical tumor cells. These data suggest that ouabain or ouabain derivatives may be potential anticancer agents.

Update in adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is an orphan malignancy that has attracted increasing attention during the last decade. Here we provide an update on advances in the field since our last review published in this journal in 2006. The Wnt/β-catenin pathway and IGF-2 signaling have been confirmed as frequently altered signaling pathways in ACC, but recent data suggest that they are probably not sufficient for malignant transformation. Thus, major players in the pathogenesis are still unknown. For diagnostic workup, comprehensive hormonal assessment and detailed imaging are required because in most ACCs, evidence for autonomous steroid secretion can be found and computed tomography or magnetic resonance imaging (if necessary, combined with functional imaging) can differentiate benign from malignant adrenocortical tumors. Surgery is potentially curative in localized tumors. Thus, we recommend a complete resection including lymphadenectomy by an expert surgeon. The pathology report should demonstrate the adrenocortical origin of the lesion (eg, by steroidogenic factor 1 staining) and provide Weiss score, resection status, and quantitation of the proliferation marker Ki67 to guide further treatment. Even after complete surgery, recurrence is frequent and adjuvant mitotane treatment improves outcome, but uncertainty exists as to whether all patients benefit from this therapy. In advanced ACC, mitotane is still the standard of care. Based on the FIRM-ACT trial, mitotane plus etoposide, doxorubicin, and cisplatin is now the established first-line cytotoxic therapy. However, most patients will experience progress and require salvage therapies. Thus, new treatment concepts are urgently needed. The ongoing international efforts including comprehensive "-omic approaches" and next-generation sequencing will improve our understanding of the pathogenesis and hopefully lead to better therapies.

Everolimus therapy for progressive adrenocortical cancer

Patients with advanced adrenocortical carcinoma (ACC) have limited treatment options after failure of chemotherapy. Tumor IGF2 expression has been shown to be amplified in the majority of cases of ACC and autocrine/paracrine activation of the IGF receptor (IGF-R) is thought to play a major role in the pathogenesis of ACC. It has been shown in vitro that inhibition of the IGF-R inhibits ACC cell proliferation. mTOR is a downstream effector of the IGFR signaling pathway; therefore, the rapamycin analog everolimus could prove to be useful for treatment of patients with ACC. Four women with ACC (ages 25-60 years) developed stage IV disease after surgery. All had progressive disease (PD) despite treatment with mitotane and other treatment modalities (etoposide, doxorubicin, cis-platinum in 3/4 patients, further streptozotocin + 5-FU in 1/4 patients, further thalidomide therapy in 2/4 patients; 1 patient progressed on an IGF-R antagonist). The patients were started on everolimus 10 mg/day orally and 2/4 patients also continued mitotane. Disease progression was monitored monthly by CT in 3/4 and after 3 months in 1/4. In all patients everolimus was well tolerated. In the three patients monitored monthly, PD was evident after 1, 3, and 4 months; in the patient evaluated after 3 months PD was also evident. In this small exploratory study, no clinically meaningful response was observed with everolimus in four patients with advanced ACC. The failure of efficacy could be related to an interaction with mitotane, multiple signaling pathways, and/or other downstream IGF-R effectors operative in the pathogenesis of ACC.

The PI3K/AKT/mTOR signaling pathway is overactivated in primary aldosteronism

Background

To date, the available non-invasive remedies for primary aldosteronism are not satisfactory in clinical practice. The phosphoinositide 3-kinase (PI3Ks)/protein kinase B (PKB or AKT)/mammalian target of rapamycin (mTOR) signaling pathway is essential for tumorigenesis and metastasis in many types of human tumors, including renal cancer, adrenal carcinoma and pheochromocytoma. The possibility that this pathway is also necessary for the pathogenesis of primary aldosteronism has not yet been explored. To answer this question, we investigated the activity of the PI3K/AKT/mTOR signaling pathway in normal adrenal glands (NAGs), primary aldosteronism (PA) patients and NCI-H295R cells.

Methodology/Principal Findings

Between January 2005 and December 2011, we retrospectively reviewed the records of 45 patients with PA. We compared clinical characteristics (age, gender and biochemical data) and the expression of phospho-AKT (p-AKT), phospho-mTOR (p-mTOR), phospho-S6 (p-S6) and vascular endothelial growth factor (VEGF) by immunohistochemical staining and western blotting, analyzing 30 aldosterone-producing adenomas (APAs), 15 idiopathic hyperaldosteronism (IHA) tissues and 12 NAGs following nephrectomy for renal tumors (control group). Compared with the control group, most of the PA patients presented with polydipsia, polyuria, resistant hypertension, profound hypokalemia, hyperaldosteronemia and decreased plasma renin activity. Compared with normal zona glomerulosa, the levels of p-AKT, p-mTOR, p-S6 and VEGF were significantly upregulated in APA and IHA. No significant differences were found between APA and IHA in the expression of these proteins. Additionally, positive correlations existed between the plasma aldosterone levels and the expression of p-AKT and p-mTOR. In vitro studies showed that mTOR inhibitor rapamycin could inhibit cell proliferation in NCI-H295R cells in a dose- and time-dependent manner. Furthermore, this inhibitor also decreased aldosterone secretion.

Conclusions

Our data suggest that the PI3K/AKT/mTOR signaling pathway, which was overactivated in APA and IHA compared with normal zona glomerulosa, may mediate aldosterone hypersecretion and participate in the development of PA.

Sunitinib Inhibits Cell Proliferation and Alters Steroidogenesis by Down-Regulation of HSD3B2 in Adrenocortical Carcinoma Cells

The multi-tyrosine kinase inhibitor sunitinib is used in the treatment of several solid tumors. Animal experiments pointed to an adrenotoxic effect of sunitinib. Therefore, we evaluated the expression of key targets of sunitinib in human adrenocortical carcinoma (ACC) tumor samples and investigated its in vitro effects in ACC cell lines. We carried out immunohistochemistry for vascular endothelial growth factor (VEGF) and its receptor (VEGF-R2) in 157 ACC samples and nine normal adrenal glands. VEGF and VEGF-R2 protein were expressed in 72 and 99% of ACC samples, respectively. Using NCI-H295 and SW13 ACC cell lines, we investigated the effects of sunitinib on cell proliferation. Sunitinib reduced dose-dependently cell viability of both NCI-H295 and SW13 cells (SW13: 0.1 μM 96 ± 7%, 1 μM 90 ± 9%*, 5 μM 62 ± 6%*, controls 100 ± 9%; *p < 0.05). To determine sunitinib effects on steroidogenesis, we measured steroid hormones in cell culture supernatant by gas chromatography-mass spectrometry. We observed a pronounced decrease of cortisol secretion (1 μM 90.1 ± 1.5%*, 5 μM 57.2 ± 0.3%*, controls 100 ± 2.4%) and a concomitant increase in the DHEA/4-androstenedione and 17-hydroxypregnenolone/17-hydroxyprogesterone ratios, indicating specific inhibition of 3β-hydroxysteroid dehydrogenase (HSD3B2). In yeast microsomes transformed with HSD3B2, no direct inhibition of HSD3B2 by sunitinib was detected. Sunitinib induced down-regulation of HSD3B2 mRNA and protein in ACC cell lines (mRNA: 1 μM 44 ± 16%*; 5 μM 22 ± 2%*; 10 μM 19 ± 4%*; protein: 1 μM 82 ± 8%; 5 μM 63 ± 8%*; 10 μM 55 ± 9%*). CYP11B1 was down-regulated at mRNA but not at protein level and CYP11A1 remained unchanged. In conclusion, target molecules of sunitinib are expressed in the vast majority of ACC samples. Sunitinib exhibits anti-proliferative effects in vitro, and appears to specifically block adrenal steroidogenesis by down-regulation of HSD3B2, rendering it a promising option for treatment of ACC.