Efficacy of the novel dual PI3-kinase/mTOR inhibitor NVP-BEZ235 in a preclinical model of adrenocortical carcinoma

Acyl-CoA synthetase 4 modulates mitochondrial function in breast cancer cells

Mitochondria are dynamic organelles that respond to cellular stress through changes in global mass, interconnection, and subcellular location. As mitochondria play an important role in tumor development and progression, alterations in energy metabolism allow tumor cells to survive and spread even in challenging conditions. Alterations in mitochondrial bioenergetics have been recently proposed as a hallmark of cancer, and positive regulation of lipid metabolism constitutes one of the most common metabolic changes observed in tumor cells. Acyl-CoA synthetase 4 (ACSL4) is an enzyme catalyzing the activation of long chain polyunsaturated fatty acids with a strong substrate preference for arachidonic acid (AA). High ACSL4 expression has been related to aggressive cancer phenotypes, including breast cancer, and its overexpression has been shown to positively regulate the mammalian Target of Rapamycin (mTOR) pathway, involved in the regulation of mitochondrial metabolism genes. However, little is known about the role of ACSL4 in the regulation of mitochondrial function and metabolism in cancer cells. In this context, our objective was to study whether mitochondrial function and metabolism, processes usually altered in tumors, are modulated by ACSL4 in breast cancer cells. Using ACSL4 overexpression in MCF-7 cells, we demonstrate that this enzyme can increase the mRNA and protein levels of essential mitochondrial regulatory proteins such as nuclear respiratory factor 1 (NRF-1), voltage-dependent anion channel 1 (VDAC1) and respiratory chain Complex III. Furthermore, respiratory parameters analysis revealed an increase in oxygen consumption rate (OCR) and in spare respiratory capacity (SRC), among others. ACSL4 knockdown in MDA-MB-231 cells led to the decrease in OCR and in SCR, supporting the role of ACSL4 in the regulation of mitochondrial bioenergetics. Moreover, ACSL4 overexpression induced an increase in glycolytic function, in keeping with an increase in mitochondrial respiratory activity. Finally, there was a decrease in mitochondrial mass detected in cells that overexpressed ACSL4, while the knockdown of ACSL4 expression in MDA-MB-231 cells showed the opposite effect. Altogether, these results unveil the role of ACSL4 in mitochondrial function and metabolism and expand the knowledge of ACSL4 participation in pathological processes such as breast cancer.

Targeting Oncogenic Wnt/β-Catenin Signaling in Adrenocortical Carcinoma Disrupts ECM Expression and Impairs Tumor Growth

Adrenocortical carcinoma (ACC) is a rare but highly aggressive cancer with limited treatment options and poor survival for patients with advanced disease. An improved understanding of the transcriptional programs engaged in ACC will help direct rational, targeted therapies. Whereas activating mutations in Wnt/β-catenin signaling are frequently observed, the β-catenin-dependent transcriptional targets that promote tumor progression are poorly understood. To address this question, we analyzed ACC transcriptome data and identified a novel Wnt/β-catenin-associated signature in ACC enriched for the extracellular matrix (ECM) and predictive of poor survival. This suggested an oncogenic role for Wnt/β-catenin in regulating the ACC microenvironment. We further investigated the minor fibrillar collagen, collagen XI alpha 1 (COL11A1), and found that COL11A1 expression originates specifically from cancer cells and is strongly correlated with both Wnt/β-catenin activation and poor patient survival. Inhibition of constitutively active Wnt/β-catenin signaling in the human ACC cell line, NCI-H295R, significantly reduced the expression of COL11A1 and other ECM components and decreased cancer cell viability. To investigate the preclinical potential of Wnt/β-catenin inhibition in the adrenal microenvironment, we developed a minimally invasive orthotopic xenograft model of ACC and demonstrated that treatment with the newly developed Wnt/β-catenin:TBL1 inhibitor Tegavivint significantly reduced tumor growth. Together, our data support that the inhibition of aberrantly active Wnt/β-catenin disrupts transcriptional reprogramming of the microenvironment and reduces ACC growth and survival. Furthermore, this β-catenin-dependent oncogenic program can be therapeutically targeted with a newly developed Wnt/β-catenin inhibitor. These results show promise for the further clinical development of Wnt/β-catenin inhibitors in ACC and unveil a novel Wnt/β-catenin-regulated transcriptome.

Preclinical Models of Adrenocortical Cancer

Adrenocortical cancer is an aggressive endocrine malignancy with an incidence of 0.72 to 1.02 per million people/year, and a very poor prognosis with a five-year survival rate of 22%. As an orphan disease, clinical data are scarce, meaning that drug development and mechanistic research depend especially on preclinical models. While a single human ACC cell line was available for the last three decades, over the last five years, many new in vitro and in vivo preclinical models have been generated. Herein, we review both in vitro (cell lines, spheroids, and organoids) and in vivo (xenograft and genetically engineered mouse) models. Striking leaps have been made in terms of the preclinical models of ACC, and there are now several modern models available publicly and in repositories for research in this area.

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.

Angiotensin II Regulates Mitochondrial mTOR Pathway Activity Dependent on Acyl-CoA Synthetase 4 in Adrenocortical Cells

Two well-known protein complexes in mammalian cells, mTOR type 1 and type 2 (mTORC1/2) are involved in several cellular processes such as protein synthesis, cell proliferation, and commonly dysregulated in cancer. An acyl-CoA synthetase type 4 (ACSL4) is one of the most recently mTORC1/2 regulators described, in breast cancer cells. The expression of ACSL4 is hormone-regulated in adrenocortical cells and required for steroid biosynthesis. mTORC1/2 have been reported to be crucial in the proliferation of human adrenocortical tumor cells H295R and interestingly reported at several subcellular locations, which has brought cell biology to the vanguard of the mTOR signaling field. In the present work, we study the regulation of mTORC1/2 activation by angiotensin II (Ang II)-the trophic hormone for adrenocortical cells-the subcellular localization of mTORC1/2 signaling proteins and the role of ACSL4 in the regulation of this pathway, in H295R cells. Ang II promotes activation by phosphorylation of mTORC1/2 pathway proteins in a time-dependent manner. Mitochondrial pools of ribosomal protein S6, protein kinase B (Akt) in threonine 308, and serine 473 and Rictor are phosphorylated and activated. Glycogen synthase kinase type 3 (GSK3) is phosphorylated and inactivated in mitochondria, favoring mTORC1 activation. Epidermal growth factor, a classic mTORC1/2 activator, promoted unique activation kinetics of mTORC1/2 pathway, except for Akt phosphorylation. Here, we demonstrate that ACSL4 is necessary for mTORC1/2 effectors phosphorylation and H295R proliferation, triggered by Ang II. Ang II promotes activation of mitochondrial mTORC1/2 signaling proteins, through ACSL4, with a direct effect on adrenocortical cellular proliferation.

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.

Metformin as a new anti-cancer drug in adrenocortical carcinoma

Adrenocortical carcinoma (ACC) is a rare heterogeneous malignancy with poor prognosis. Since radical surgery is the only available treatment, more specific and effective drugs are urgently required. The anti-diabetic drug metformin has been associated with a decreased cancer prevalence and mortality in several solid tumors, prompting its possible use for ACC treatment.

This paper evaluates the in vitro and in vivo anti-cancer effects of metformin using the ACC cell model H295R.

Metformin treatment significantly reduces cell viability and proliferation in a dose- and time-dependent manner and associates with a significant inhibition of ERK1/2 and mTOR phosphorylation/activation, as well as with stimulation of AMPK activity. Metformin also triggers the apoptotic pathway, shown by the decreased expression of Bcl-2 and HSP27, HSP60 and HSP70, and enhanced membrane exposure of annexin V, resulting in activation of caspase-3 apoptotic effector. Metformin interferes with the proliferative autocrine loop of IGF2/IGF-1R, which supports adrenal cancer growth. Finally, in the ACC xenograft mouse model, obtained by subcutaneous injection of H295R cells, metformin intraperitoneal administration inhibits tumor growth, confirmed by the significant reduction of Ki67%.

Our data suggest that metformin inhibits H295R cell growth both in vitro and in vivo. Further preclinical studies are necessary to validate the potential anti-cancer effect of metformin in patients affected by ACC.

The next step: mechanisms driving adrenocortical carcinoma metastasis

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

The role of microRNAs in the pathophysiology of adrenal tumors

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression in a sequence-specific manner. Due to its association with an assortment of diseases, miRNAs have been extensively studied in the last decade. In this review, the current understanding of the role of miRNAs in the pathophysiology of adrenal tumors is discussed. The recent contributions of high-throughput miRNA profiling studies have identified miRNAs that have functional and molecular roles in adrenal tumorigenesis. With respect to the biological heterogeneity of adrenal tumors and the limitations of the current treatments, an improved understanding of miRNAs may hold potential diagnostic and therapeutic value to facilitate better clinical management.

Establishment of a mouse xenograft model of metastatic adrenocortical carcinoma

Adrenocortical carcinoma is a rare neoplasm with a poor prognosis. Very important advances have been made in the identification of the genetic determinants of adrenocortical carcinoma pathogenesis but our understanding is still limited about the mechanisms that determine cancer spread and metastasis. One major problem hindering preclinical experimentation for new therapies for adrenocortical carcinoma is represented by the lack of suitable animal models for metastatic disease. With the aim to overcome these limitations, in this study we tested several protocols in order to establish a mouse xenograft model of metastatic adrenocortical carcinoma. The most efficient method, based upon intrasplenic injection followed by splenectomy, produced metastases with high efficiency, whose development could be followed over time by bioluminescence measurements. We expect that the availability of this model will greatly improve the possibilities for preclinical testing of new treatments for advanced-stage disease.

P53/Rb inhibition induces metastatic adrenocortical carcinomas in a preclinical transgenic model

Adrenocortical carcinoma (ACC) is a rare cancer with poor prognosis. Pan-genomic analyses identified p53/Rb and WNT/β-catenin signaling pathways as main contributors to the disease. However, isolated β-catenin constitutive activation failed to induce malignant progression in mouse adrenocortical tumors. Therefore, there still was a need for a relevant animal model to study ACC pathogenesis and to test new therapeutic approaches. Here, we have developed a transgenic mice model with adrenocortical specific expression of SV40 large T-antigen (AdTAg mice), to test the oncogenic potential of p53/Rb inhibition in the adrenal gland. All AdTAg mice develop large adrenal carcinomas that eventually metastasize to the liver and lungs, resulting in decreased overall survival. Consistent with ACC in patients, adrenal tumors in AdTAg mice autonomously produce large amounts of glucocorticoids and spontaneously activate WNT/β-catenin signaling pathway during malignant progression. We show that this activation is associated with downregulation of secreted frizzled related proteins (Sfrp) and Znrf3 that act as inhibitors of the WNT signaling. We also show that mTORC1 pathway activation is an early event during neoplasia expansion and further demonstrate that mTORC1 pathway is activated in ACC patients. Preclinical inhibition of mTORC1 activity induces a marked reduction in tumor size, associated with induction of apoptosis and inhibition of proliferation that results in normalization of corticosterone plasma levels in AdTAg mice. Altogether, these data establish AdTAg mice as the first preclinical model for metastatic ACC.

MicroRNA-99a inhibits insulin-induced proliferation, migration, dedifferentiation, and rapamycin resistance of vascular smooth muscle cells by inhibiting insulin-like growth factor-1 receptor and mammalian target of rapamycin

Patients with type 2 diabetes mellitus (T2DM) are characterized by insulin resistance and are subsequently at high risk for atherosclerosis. Hyperinsulinemia has been associated with proliferation, migration, and dedifferentiation of vascular smooth muscle cells (VSMCs) during the pathogenesis of atherosclerosis. Moreover, insulin-like growth factor-1 receptor (IGF-1R) and mammalian target of rapamycin (mTOR) have been demonstrated to be the underlying signaling pathways. Recently, microRNA-99a (miR-99a) has been suggested to regulate the phenotypic changes of VSMCs in cancer cells. However, whether it is involved in insulin-induced changes of VSCMs has not been determined. In this study, we found that insulin induced proliferation, migration, and dedifferentiation of mouse VSMCs in a dose-dependent manner. Furthermore, the stimulating effects of high-dose insulin on proliferation, migration, and dedifferentiation of mouse VSMCs were found to be associated with the attenuation of the inhibitory effects of miR-99a on IGF-1R and mTOR signaling activities. Finally, we found that the inducing effect of high-dose insulin on proliferation, migration, and dedifferentiation of VSMCs was partially inhibited by an active mimic of miR-99a. Taken together, these results suggest that miR-99a plays a key regulatory role in the pathogenesis of insulin-induced proliferation, migration, and phenotype conversion of VSMCs at least partly via inhibition of IGF-1R and mTOR signaling. Our results provide evidence that miR-99a may be a novel target for the treatment of hyperinsulinemia-induced atherosclerosis.

Effect of API-1 and FR180204 on cell proliferation and apoptosis in human DLD-1 and LoVo colorectal cancer cells

The activation of the phosphatidylinositol-3 kinase/v-akt murine thymoma viral oncogene homolog (Akt) and mitogen activated protein kinase kinase/extracellular signal-regulated kinase (ERK) pathways are implicated in the majority of cancers. Selective inhibition of Akt and ERK represents a potential approach for cancer therapy. Therefore, the present study aimed to investigate the apoptotic and anti-proliferative effects of the novel and selective Akt inhibitor 4-amino-5,8-dihydro-5-oxo-8-β-D-ribofuranosyl-pyrido[2,3-d]pyrimidine-6-carboxamide (API-1) and selective ERK1/2 inhibitor FR180204 (FR) alone and in combination on colorectal cancer (CRC) cells (DLD-1 and LoVo). In addition, the effects of API-1 and FR on Akt and ERK signaling pathways were also investigated. The effects of the agents on DLD-1 and LoVo cells were evaluated in terms of cell viability, cytotoxicity, DNA synthesis rate, DNA fragmentation and caspase-3 activity levels. In addition, quantitative reverse transcription-polymerase chain reaction and western blot analysis were performed to examine relevant mRNA and protein levels. The present study observed that the combination of FR with API-1 resulted in significant apoptosis and cytotoxicity compared with any single agent alone in a time-dependent manner in these cells. Also, treatment with FR and API-1 in combination decreased the expression levels of B-cell lymphoma-2 (BCL2), Bcl-2-like1, cyclin D1 and cMYC, and increased the expression levels of BCL2-associated X protein and BCL2 antagonist/killer via phosphorylated Akt and phosphorylated ERK1/2 downregulation. The combination of Akt and ERK1/2 inhibitors resulted in enhanced apoptotic and anti-proliferative effects against CRC cells. The present study hypothesizes that the combination of FR and API-1 in CRC cells may contribute toward potential anti-carcinogenic effects. Additional analyses using other cancer cell lines and animal models are required to confirm these findings in vitro and in vivo.

Insulin-like growth factor--phosphatidylinositol 3 kinase signaling in canine cortisol-secreting adrenocortical tumors

Background

Hypercortisolism is a common endocrine disorder in dogs, caused by a cortisol‐secreting adrenocortical tumor (AT) in approximately 15% of cases. In adrenocortical carcinomas of humans, activation of the phosphatidylinositol 3 kinase (PI3K) signaling pathway by insulin‐like growth factor (IGF) signaling represents a promising therapeutic target.

Objectives

To investigate the involvement of PI3K signaling in the pathogenesis of ATs in dogs and to identify pathway components that may hold promise as future therapeutic targets or as prognostic markers.

Animals

Analyses were performed on 36 canine cortisol‐secreting ATs (11 adenomas and 25 carcinomas) and 15 normal adrenal glands of dogs.

Methods

mRNA expression analysis was performed for PI3K target genes, PI3K inhibitor phosphatase and tensin homolog (PTEN), IGFs, IGF receptors, IGF binding proteins and epidermal growth factor receptors. Mutation analysis was performed on genes encoding PTEN and PI3K catalytic subunit (PIK3CA).

Results

Target gene expression indicated PI3K activation in carcinomas, but not in adenomas. No amino acid‐changing mutations were detected in PTEN or PIK3CA and no significant alterations in IGF‐II or IGFR1 expression were detected. In carcinomas, ERBB2 expression tended to be higher than in normal adrenal glands, and higher expression of inhibitor of differentiation 1 and 2 (ID1 and ID2) was detected in carcinomas with recurrence within 2.5 years after adrenalectomy.

Conclusions and Clinical Importance

Based on these results, ERBB2 might be a promising therapeutic target in ATs in dogs, whereas ID1 and 2 might be valuable as prognostic markers and therapeutic targets.

Animal models of adrenocortical tumorigenesis

This comparative review highlights animal models of adrenocortical neoplasia useful either for mechanistic studies or translational research. Three model species-mouse, ferret, and dog-are detailed. The relevance of each of these models to spontaneous and inherited adrenocortical tumors in humans is discussed.

Effect of Orexin-A on Cortisol Secretion in H295R Cells via p70S6K/4EBP1 Signaling Pathway

Orexin-A is a neuropeptide that orchestrates diverse central and peripheral processes. It is now clear that orexin system plays a central role in the regulation of endocrine, paracrine, and neurocrine. It is involved in the regulation of growth hormone, adrenocorticotropic hormone, thyroid, mineralocorticoid, and cortisol secretion. These hormones may also serve as a kind of signal linking energy balance regulation, reproduction, stress response, and cardiovascular regulation. Many studies have demonstrated the ability of orexin-A to regulate adrenocortical cells through the MAPK (mitogen-activated protein kinases) pathway. The aim of our study is to investigate the effect of orexin-A on cortisol secretion via the protein 70 ribosomal protein S6 kinase-1 (p70S6K) and eukaryotic translation initiation factor 4E binding proteins (4EBP1) signaling pathway in adrenocortical cells. We reported the first evidence that orexin-A stimulated p70S6K and 4EBP1 in human H295R adrenocortical cells in a concentration and time-dependent manner. 10(-6) M orexin-A treatment for 1 hour was the most potent. Our results also indicated that p70S6K and 4EBP1 kinases participated in controlling cortisol secretion via OX1 receptor in H295R cells, which implied important role of p70S6K and 4EBP1 kinases in regulating adrenal function induced by orexin-A.

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.

Role of the ERK1/2 pathway in tumor chemoresistance and tumor therapy

Chemotherapy is one of the important methods for treatment in tumors. However, many tumor patients may experience tumor recurrence because of treatment failure due to chemoresistance. Although many signaling pathways could influence chemoresistance of tumor cells, the extracellular signal-regulated kinase 1 and 2 (ERK1/2) pathway has gained significant attention because of its implications in signaling and which has crosstalk with other signaling pathways. Extensive studies conclude that ERK1/2 pathway is responding to chemoresistance in many kinds of malignant tumors. The aim of this review is to discuss on the role of ERK1/2 pathway in chemoresistance and therapy of tumors. A comprehensive understanding of ERK1/2 pathway in chemoresistance of tumors could provide novel avenues for treatment strategies of tumors.

mTOR pathway in colorectal cancer: an update

The mammalian target of rapamycin (mTOR) has emerged as a potential target for drug development, particularly due to the fact that it plays such a crucial role in cancer biology. In addition, next-generation mTOR inhibitors have become available, marking an exciting new phase in mTOR-based therapy. However, the verdict on their therapeutic efectiveness remains unclear. Here we review phosphatidylinositol-3-kinase (PI3K)/Akt/mTOR signaling as one of the primary mechanisms for sustaining tumor outgrowth and metastasis, recent advances in the development of mTOR inhibitors, and current studies addressing mTOR activation/inhibition in colorectal cancer (CRC). We will also discuss our recent comparative study of diferent mTOR inhibitors in a population of colon cancer stem cells (CSCs), and current major challenges for achieving individualized drug therapy using kinase inhibitors.

Pediatric adrenocortical tumors: diagnosis, management and advancements in the understanding of the genetic basis and therapeutic implications

Adrenocortical tumors (ACTs) may be sporadic or related to inherited genetic syndromes. Uncovering the molecular defects underlying these genetic syndromes has revealed key signaling pathways involved in adrenocortical tumorigenesis. Although the understanding of ACT biology has improved, to date, very few potential prognostic molecular markers of childhood ACTs have been identified. In this review, we summarize the current knowledge of the epidemiology, clinical presentation, diagnosis, prognosis and treatment options for pediatric patients with ACTs. A review of the genetic basis of adrenocortical tumorigenesis is presented, focusing on the main molecular abnormalities involved in the tumorigenic process and potential novel therapy targets that have been generated, or are being generated, with the discovery of these molecular defects.

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.

Adrenocortical carcinoma: the management of metastatic disease

Adrenocortical cancer is a rare malignancy. While surgery is the cornerstone of the management of localized disease, metastatic disease is hard to treat. Cytotoxic chemotherapy and mitotane have been utilized with a variable degree of benefit and few long-term responses. A growing understanding of the molecular pathogenesis of this malignancy as well as multidisciplinary and multi-institutional collaborative efforts will result in better defined targets and subsequently, effective novel therapies.

Curcumin significantly enhances dual PI3K/Akt and mTOR inhibitor NVP-BEZ235-induced apoptosis in human renal carcinoma Caki cells through down-regulation of p53-dependent Bcl-2 expression and inhibition of Mcl-1 protein stability

The PI3K/Akt and mTOR signaling pathways are important for cell survival and growth, and they are highly activated in cancer cells compared with normal cells. Therefore, these signaling pathways are targets for inducing cancer cell death. The dual PI3K/Akt and mTOR inhibitor NVP-BEZ235 completely inhibited both signaling pathways. However, NVP-BEZ235 had no effect on cell death in human renal carcinoma Caki cells. We tested whether combined treatment with natural compounds and NVP-BEZ235 could induce cell death. Among several chemopreventive agents, curcumin, a natural biologically active compound that is extracted from the rhizomes of Curcuma species, markedly induced apoptosis in NVP-BEZ235-treated cells. Co-treatment with curcumin and NVP-BEZ235 led to the down-regulation of Mcl-1 protein expression but not mRNA expression. Ectopic expression of Mcl-1 completely inhibited curcumin plus NVP-NEZ235-induced apoptosis. Furthermore, the down-regulation of Bcl-2 was involved in curcumin plus NVP-BEZ235-induced apoptosis. Curcumin or NVP-BEZ235 alone did not change Bcl-2 mRNA or protein expression, but co-treatment reduced Bcl-2 mRNA and protein expression. Combined treatment with NVP-BEZ235 and curcumin reduced Bcl-2 expression in wild-type p53 HCT116 human colon carcinoma cells but not p53-null HCT116 cells. Moreover, Bcl-2 expression was completely reversed by treatment with pifithrin-α, a p53-specific inhibitor. Ectopic expression of Bcl-2 also inhibited apoptosis in NVP-BE235 plus curcumin-treated cells. In contrast, NVP-BEZ235 combined with curcumin did not have a synergistic effect on normal human skin fibroblasts and normal human mesangial cells. Taken together, combined treatment with NVP-BEZ235 and curcumin induces apoptosis through p53-dependent Bcl-2 mRNA down-regulation at the transcriptional level and Mcl-1 protein down-regulation at the post-transcriptional level.

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.

Lack of long-lasting effects of mitotane adjuvant therapy in a mouse xenograft model of adrenocortical carcinoma

Mitotane is a widely used drug in the therapy of adrenocortical carcinoma (ACC). It is important to set up preclinical protocols to study the possible synergistic effects of its association with new drugs for ACC therapy. We assessed the efficacy of different routes of administration of mitotane (i.p. and oral) in inhibiting growth of H295R ACC cell xenografts in an adjuvant setting. Both formulations of mitotane could inhibit H295R xenografts growth only at short times after carcinoma cells inoculation, even though plasma mitotane levels approached or fell within the therapeutic range in humans. Our results show that mitotane adjuvant therapy is inadequate to antagonize long-term growth of H295R cancer cells xenografts and that care should then be taken in the design of preclinical protocols to evaluate the performance of new drugs in association with mitotane.

The combination of novel targeted molecular agents and radiation in the treatment of pediatric gliomas

Brain tumors are the most common solid pediatric malignancy. For high-grade, recurrent, or refractory pediatric brain tumors, radiation therapy (XRT) is an integral treatment modality. In the era of personalized cancer therapy, molecularly targeted agents have been designed to inhibit pathways critical to tumorigenesis. Our evolving knowledge of genetic aberrations in pediatric gliomas is being exploited with the use of specific targeted inhibitors. These agents are additionally being combined with XRT to increase the efficacy and duration of local control. In this review, we discuss novel agents targeting three different pathways in gliomas, and their potential combination with XRT. BRAF is a serine/threonine kinase in the RAS/RAF/MAPK kinase pathway, which is integral to cellular division, survival, and metabolism. Two-thirds of pilocytic astrocytomas, a low-grade pediatric glioma, contain a translocation within the BRAF gene called KIAA1549:BRAF that causes an overactivation of the MEK/MAPK signaling cascade. In vitro and in vivo data support the use of MEK or mammalian target of rapamycin (mTOR) inhibitors in low-grade gliomas expressing this translocation. Additionally, 15-20% of high-grade pediatric gliomas express BRAF V600E, an activating mutation of the BRAF gene. Pre-clinical in vivo and in vitro data in BRAF V600E gliomas demonstrate dramatic cooperation between XRT and small molecule inhibitors of BRAF V600E. Another major signaling cascade that plays a role in pediatric glioma pathogenesis is the PI3-kinase (PI3K)/mTOR pathway, known to be upregulated in the majority of high- and low-grade pediatric gliomas. Dual PI3K/mTOR inhibitors are in clinical trials for adult high-grade gliomas and are poised to enter studies of pediatric tumors. Finally, many brain tumors express potent stimulators of angiogenesis that render them refractory to treatment. An analog of thalidomide, CC-5103 increases the secretion of critical cytokines of the tumor microenvironment, including IL-2, IFN-γ, TNF-α, and IL-10, and is currently being evaluated in clinical trials for the treatment of recurrent or refractory pediatric central nervous system tumors. In summary, several targeted inhibitors with radiation are currently under investigation in both translational bench research and early clinical trials. This review article summarizes the molecular rationale for, and the pre-clinical data supporting the combinations of these targeted agents with other anti-cancer agents and XRT in pediatric gliomas. In many cases, parallels are drawn to molecular mechanisms and targeted inhibitors of adult gliomas. We additionally discuss the potential mechanisms underlying the efficacy of these agents.