Rosiglitazone induces autophagy in H295R and cell cycle deregulation in SW13 adrenocortical cancer cells

Advances in translational research of the rare cancer type adrenocortical carcinoma

Adrenocortical carcinoma is a rare malignancy with an annual worldwide incidence of 1-2 cases per 1 million and a 5-year survival rate of <60%. Although adrenocortical carcinoma is rare, such rare cancers account for approximately one third of patients diagnosed with cancer annually. In the past decade, there have been considerable advances in understanding the molecular basis of adrenocortical carcinoma. The genetic events associated with adrenocortical carcinoma in adults are distinct from those of paediatric cases, which are often associated with germline or somatic TP53 mutations and have a better prognosis. In adult primary adrenocortical carcinoma, the main somatic genetic alterations occur in genes that encode proteins involved in the WNT-β-catenin pathway, cell cycle and p53 apoptosis pathway, chromatin remodelling and telomere maintenance pathway, cAMP-protein kinase A (PKA) pathway or DNA transcription and RNA translation pathways. Recently, integrated molecular studies of adrenocortical carcinomas, which have characterized somatic mutations and the methylome as well as gene and microRNA expression profiles, have led to a molecular classification of these tumours that can predict prognosis and have helped to identify new therapeutic targets. In this Review, we summarize these recent translational research advances in adrenocortical carcinoma, which it is hoped could lead to improved patient diagnosis, treatment and outcome.

Peroxisome Proliferator-Activated Receptors and the Hallmarks of Cancer

Peroxisome proliferator-activated receptors (PPARs) function as nuclear transcription factors upon the binding of physiological or pharmacological ligands and heterodimerization with retinoic X receptors. Physiological ligands include fatty acids and fatty-acid-derived compounds with low specificity for the different PPAR subtypes (alpha, beta/delta, and gamma). For each of the PPAR subtypes, specific pharmacological agonists and antagonists, as well as pan-agonists, are available. In agreement with their natural ligands, PPARs are mainly focused on as targets for the treatment of metabolic syndrome and its associated complications. Nevertheless, many publications are available that implicate PPARs in malignancies. In several instances, they are controversial for very similar models. Thus, to better predict the potential use of PPAR modulators for personalized medicine in therapies against malignancies, it seems necessary and timely to review the three PPARs in relation to the didactic concept of cancer hallmark capabilities. We previously described the functions of PPAR beta/delta with respect to the cancer hallmarks and reviewed the implications of all PPARs in angiogenesis. Thus, the current review updates our knowledge on PPAR beta and the hallmarks of cancer and extends the concept to PPAR alpha and PPAR gamma.

Enhancing autophagy in Alzheimer's disease through drug repositioning

Alzheimer's disease (AD) is one of the biggest human health threats due to increases in aging of the global population. Unfortunately, drugs for treating AD have been largely ineffective. Interestingly, downregulation of macroautophagy (autophagy) plays an essential role in AD pathogenesis. Therefore, targeting autophagy has drawn considerable attention as a therapeutic approach for the treatment of AD. However, developing new therapeutics is time-consuming and requires huge investments. One of the strategies currently under consideration for many diseases is "drug repositioning" or "drug repurposing". In this comprehensive review, we have provided an overview of the impact of autophagy on AD pathophysiology, reviewed the therapeutics that upregulate autophagy and are currently used in the treatment of other diseases, including cancers, and evaluated their repurposing as a possible treatment option for AD. In addition, we discussed the potential of applying nano-drug delivery to neurodegenerative diseases, such as AD, to overcome the challenge of crossing the blood brain barrier and specifically target molecules/pathways of interest with minimal side effects.

17β-estradiol rescues the damage of thiazolidinedione on chicken Sertoli cell proliferation via adiponectin

Thiazolidinedione (TZD) is an oral anti-diabetic drug that exhibits some side effects on the male reproductive system by interfering with the steroidogenesis and androgenic activity and also shows anti-proliferative effect on several cell types. This study investigated the effect of TZD on immature chicken Sertoli cell (SC) proliferation and the potential mechanism by which 17β-estradiol regulated this process. Chicken SC viability was investigated under different treatment concentration and time of TZD. 17β-estradiol (0.001 μM, 24 h) was added to analyze its effects on TZD-mediated cell viability, cell metabolic activity, cell growth, cell cycle progression, reactive oxygen species (ROS) level, antioxidant enzyme activity, mitochondria activity, oxygen consumption rate, adenosine triphosphate (ATP) level, and mitochondrial respiratory chain enzyme activity, adiponectin expression and several cell proliferation-related genes mRNA and protein levels. We performed the microRNA (miRNA) array to find TZD-induced differentially expressed miRNAs and validated whether miR-1577 can target on adiponectin via the dual luciferase reporter assay, as well as verified the effect of adiponectin addition with different concentrations on the SC viability. Further, SCs were transfected with miR-1577 agomir (a double-stranded synthetic miRNA mimic) in the presence or absence of TZD and antagomir (a single-stranded synthetic miRNA inhibitor) in the presence or absence of 17β-estradiol to analyze whether miR-1577 was involved in TZD-mediated SC proliferation and whether 17β-estradiol regulated this process. Results showed that TZD significantly inhibited SC viability, cell metabolic activity, cell growth, and cell cycle progression, while increased adiponectin level and ROS generation. TZD-treated SCs presented decreases of antioxidant enzyme activity, mitochondria activity, basal and maximal respiration, ATP production and level, mitochondrial respiratory chain enzyme activity, and mRNA and protein expressions of several cell proliferation-related genes, as well as the significant alteration of miRNA expressions (a total number of 55 miRNAs were up-regulated whereas 53 miRNAs down-regulated). Whereas, 17β-estradiol played a positive role in chicken SC proliferation and rescued the damage of TZD on SC proliferation by up-regulating miR-1577 expression whose target gene was validated to be the adiponectin. In addition, exogenous adiponectin (more than 1 μg/ml) treatment exhibited a significant inhibition on the SC viability. Transfection of miR-1577 agomir promoted the SC proliferation via down-expressed adiponectin, and increased the mitochondrial function and cell proliferation-related gene expression, while TZD weakened the positive effect of miR-1577 agomir on SCs. On the other hand, transfection of miR-1577 antagomir inhibited SC proliferation by producing the opposite effects on above parameters, while 17β-estradiol attenuated the negative effect of miR-1577 antagomir on SCs. These findings suggest down-expressed miR-1577 is involved in the regulation of TZD-inhibited SC proliferation through increasing adiponectin level, and this damage of TZD on the immature chicken SC proliferation can be ameliorated by appropriate dose of exogenous 17β-estradiol treatment. This study provides an insight into the cytoprotective effect of 17β-estradiol on TZD-damaged SC proliferation and may suggest a potential strategy for reducing the risk of SC dysfunction caused by the abuse of TZD.

Long Non-Coding RNA H19 Expression Correlates with Autophagy Process in Adrenocortical Carcinoma

Adrenocortical carcinoma (ACC) is characterized by poor prognosis and high mortality. The suppression of the long-non-coding RNA H19, counterbalanced by IGF2 over-expression, leads to down-regulation of the autophagy markers, high proliferation rate and metastatic potential in patients affected by ACC. The administration of the deacetylase inhibitors (DACi) panobinostat, trichostatin A (TSA) and SAHA affected the cell viability of H295R monolayer and spheroids and induced the over-expression of H19 and autophagy transcripts. H19 knock down in H295R cells was not able to modulate the expression level of autophagy transcripts. Instead, H19 knock down was able to impede the ability of DACi to modulate the protein level of the autophagy markers. Furthermore, the administration of higher concentration of DACi was able to down-regulate the protein level of Beclin1 and p62 and to induce the conversion of LC3B-I into the active LC3B-II form, thus confirming an active autophagic process. Neither the active protein level nor the activity of caspases 8 and 3 was prompted by the DACi, thus excluding the involvement of the executioners of apoptosis in H295R decay. The DACi restore H19, the autophagy markers and trigger cell death in ACC cells. The re-activation of autophagy would represent a novel strategy for the treatment of patients affected by this severe malignancy.

Modulation of Autophagy in Adrenal Tumors

Adrenal masses are one of the most common tumors in humans. The majority are benign and non-functioning and therefore do not require immediate treatment. In contrast, the rare adrenal malignant tumors are often highly aggressive and with poor prognosis. Besides usually being detected in advanced stages, often already with metastases, one of the reasons of the unfavorable outcome of the patients with adrenal cancer is the absence of effective treatments. Autophagy is one of the intracellular pathways targeted by several classes of chemotherapeutics. Mitotane, the most commonly used drug for the treatment of adrenocortical carcinoma, was recently shown to also modulate autophagy. Autophagy is a continuous programmed cellular process which culminates with the degradation of cellular organelles and proteins. However, being a dynamic mechanism, understanding the autophagic flux can be highly complex. The role of autophagy in cancer has been described paradoxically: initially described as a tumor pro-survival mechanism, different studies have been showing that it may result in other outcomes, namely in tumor cell death. In adrenal tumors, this dual role of autophagy has also been addressed in recent years. Studies reported both induction and inhibition of autophagy as a treatment strategy of adrenal malignancies. Importantly, most of these studies were performed using cell lines. Consequently clinical studies are still required. In this review, we describe what is known about the role of autophagy modulation in treatment of adrenal tumors. We will also highlight the aspects that need further evaluation to understand the paradoxical role of autophagy in adrenal tumors.

PPAR-gamma agonists: Potential modulators of autophagy in obesity

Autophagy pathways are involved in the pathogenesis of some obesity related health problems. As obesity is a nutrient sufficiency condition, autophagy process can be altered in obesity through AMP activated protein kinase (AMPK) inhibition. Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) as the main modulator of adipogenesis process can be effective in the regulation of obesity related phenotypes. As well, it has been revealed that PPAR-gamma and its agonists can regulate autophagy in different normal or cancer cells. However, their effects on autophagy modulation in obesity have been investigated in the limited number of studies. In the current comprehensive mechanistic review, we aimed to investigate the possible mechanisms of action of PPAR-gamma on the process of autophagy in obesity through narrating the effects of PPAR-gamma on autophagy in the non-obesity conditions. Moreover, mode of action of PPAR-gamma agonists on autophagy related implications comprehensively reviewed in the various studies. Understanding the different effects of PPAR-gamma agonists on autophagy in obesity can help to develop a new approach to management of obesity.

PPAR-γ Modulators as Current and Potential Cancer Treatments

Worldwide, cancer has become one of the leading causes of mortality. Peroxisome Proliferator-Activated Receptors (PPARs) is a family of critical sensors of lipids as well as regulators of diverse metabolic pathways. They are also equipped with the capability to promote eNOS activation, regulate immunity and inflammation response. Aside from the established properties, emerging discoveries are also made in PPAR's functions in the cancer field. All considerations are given, there exists great potential in PPAR modulators which may hold in the management of cancers. In particular, PPAR-γ, the most expressed subtype in adipose tissues with two isoforms of different tissue distribution, has been proven to be able to inhibit cell proliferation, induce cell cycle termination and apoptosis of multiple cancer cells, promote intercellular adhesion, and cripple the inflamed state of tumor microenvironment, both on transcriptional and protein level. However, despite the multi-functionalities, the safety of PPAR-γ modulators is still of clinical concern in terms of dosage, drug interactions, cancer types and stages, etc. This review aims to consolidate the functions of PPAR-γ, the current and potential applications of PPAR-γ modulators, and the challenges in applying PPAR-γ modulators to cancer treatment, in both laboratory and clinical settings. We sincerely hope to provide a comprehensive perspective on the prospect of PPAR-γ applicability in the field of cancer treatment.

Autophagy-Related Proteins Are Differentially Expressed in Adrenal Cortical Tumor/Pheochromocytoma and Associated with Patient Prognosis

The aim of this research was to evaluate the expression and concomitant implications of LC3A, LC3B, beclin-1, and p62, which are key components of autophagy in human adrenal gland tumors. Tissue microarray was made for 321 cases of adrenal gland tumor (adrenal cortical adenoma (ACA): 115, adrenal cortical carcinoma (ACC): 17, and pheochromocytoma (PCC): 189). Immunohistochemical staining was performed for beclin-1, p62, LC3A, and LC3B, and the results were compared with the patients’ clinicopathologic parameters. LC3A, LC3B, beclin-1, and LC3B isolated single positive cells (ISPC) positivity rates were higher in PCC than in adrenal cortical tumor (ACT), whereas p62 positivity was lower in PCC than in ACT. The proportion of positive LC3B (ISPC) was higher in ACC than in ACA. In addition, the proportion of cells positive for p62 and LC3B (ISPC) was significantly higher in PCCs with a GAPP score of ≥3. In univariate Cox analysis, p62 positivity (p = 0.014) and the presence of p62 (ISPC) (p = 0.001) were associated with shorter disease-free survival in PCC. Moreover, p62 positivity was predictive of shorter overall survival (OS) in patients with PCC by multivariate analysis (relative risk, 6.240; 95% CI, 1.434–27.15; p = 0.015). Differences were found in the expression of autophagy-related proteins according to adrenal gland tumor types. Compared to ACT, the proportion of LC3A, LC3B, beclin-1, and LC3B (ISPC) positivity was higher in PCC, whereas p62 positivity was lower. Similarly, p62 positivity in PCC was associated with patient prognosis of OS.

Peroxisome Proliferator-Activated Receptors as Molecular Links between Caloric Restriction and Circadian Rhythm

The circadian rhythm plays a chief role in the adaptation of all bodily processes to internal and environmental changes on the daily basis. Next to light/dark phases, feeding patterns constitute the most essential element entraining daily oscillations, and therefore, timely and appropriate restrictive diets have a great capacity to restore the circadian rhythm. One of the restrictive nutritional approaches, caloric restriction (CR) achieves stunning results in extending health span and life span via coordinated changes in multiple biological functions from the molecular, cellular, to the whole-body levels. The main molecular pathways affected by CR include mTOR, insulin signaling, AMPK, and sirtuins. Members of the family of nuclear receptors, the three peroxisome proliferator-activated receptors (PPARs), PPARα, PPARβ/δ, and PPARγ take part in the modulation of these pathways. In this non-systematic review, we describe the molecular interconnection between circadian rhythm, CR-associated pathways, and PPARs. Further, we identify a link between circadian rhythm and the outcomes of CR on the whole-body level including oxidative stress, inflammation, and aging. Since PPARs contribute to many changes triggered by CR, we discuss the potential involvement of PPARs in bridging CR and circadian rhythm.

Peroxisome Proliferator-Activated Receptors and Caloric Restriction-Common Pathways Affecting Metabolism, Health, and Longevity

Caloric restriction (CR) is a traditional but scientifically verified approach to promoting health and increasing lifespan. CR exerts its effects through multiple molecular pathways that trigger major metabolic adaptations. It influences key nutrient and energy-sensing pathways including mammalian target of rapamycin, Sirtuin 1, AMP-activated protein kinase, and insulin signaling, ultimately resulting in reductions in basic metabolic rate, inflammation, and oxidative stress, as well as increased autophagy and mitochondrial efficiency. CR shares multiple overlapping pathways with peroxisome proliferator-activated receptors (PPARs), particularly in energy metabolism and inflammation. Consequently, several lines of evidence suggest that PPARs might be indispensable for beneficial outcomes related to CR. In this review, we present the available evidence for the interconnection between CR and PPARs, highlighting their shared pathways and analyzing their interaction. We also discuss the possible contributions of PPARs to the effects of CR on whole organism outcomes.

New insights into molecular mechanisms of rosiglitazone in monotherapy or combination therapy against cancers

Rosiglitazone (ROSI), a member of thiazolidinediones (TZDs) which act as high-affinity agonists of the nuclear receptor peroxisome-proliferator-activated receptor-γ (PPARγ), is clinically used as an antidiabetic drug which could attenuate the insulin resistance associated with obesity, hypertension, and impaired glucose tolerance in humans. However, recent studies reported that ROSI had significant anticancer effects on various human malignant tumor cells. Mounting evidence indicated that ROSI could exert anticancer effects through PPARγ-dependent or PPARγ-independent ways. In this review, we summarized the PPARγ-dependent antitumor activities of ROSI, which included apoptosis induction, inhibition of cell proliferation and cancer metastasis, reversion of multidrug resistance, reduction of immune suppression, autophagy induction, and antiangiogenesis; and the PPARγ-independent antitumor activities of ROSI, which included inhibition of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway, inhibition of prostaglandin E2 (PGE₂), increasing MAPK phosphatase 1 (MKP-1) expression and regulation of other apoptosis-related cell factors. In addition, we discussed the anti-cancer application of ROSI by monotherapy or combination therapy with present chemotherapeutic drugs in vitro and in vivo. Moreover, we reviewed the phase I cancer clinical trials related to ROSI combined with chemotherapeutics and phase II trials about the anti-cancer effects of ROSI monotherapy and the radiotherapy sensitivity of ROSI.

Nutrient excess and autophagic deficiency: explaining metabolic diseases in obesity

Over-nutrition and a sedentary lifestyle are the driving forces behind the development of metabolic diseases. Conversely, caloric restriction and exercise have proven to be the most effective strategies in combating metabolic diseases. Interestingly, exercise and caloric restriction share a common feature: both represent a potent mechanism for upregulating autophagy. Autophagy is rapidly induced by nutrient deprivation, and conversely, inactivated by amino acids as well as growth factors (e.g. insulin). Here, we review evidence demonstrating that autophagy may indeed be attenuated in metabolic tissue such as liver, muscle, and adipose, in the context of obesity. We also highlight the mechanistic basis by which defective autophagy may contribute to the manifestation of metabolic diseases. This includes a compromised ability of the cell to perform quality control on the mitochondrial matrix, since autophagy plays a pivotal role in the degradation of defective mitochondria. Similarly, autophagy also plays an indispensable role in the clearance of protein aggregates and redundant large protein platforms such as inflammasomes. Autophagy might also play a key role in the metabolism of endotoxins, implicating the importance of autophagy in the pathogenesis of metabolic endotoxemia. These observations underpin an unprecedented role of autophagy in the manifestation of obesity-induced metabolic derangement.

Carnitine induces autophagy and restores high-fat diet-induced mitochondrial dysfunction

OBJECTIVE

Autophagy is suppressed in skeletal muscle and the liver with insulin resistance induced by a high-fat diet. Autophagy is essential for maintaining mitochondrial function, and dysfunctional mitochondria are associated with insulin resistance. As carnitine treatment is well known to improve insulin resistance by promoting mitochondrial function, we investigated if carnitine affects autophagy in the skeletal muscle of a high-fat diet-induced rodent model of obesity.

RESULTS

After 6weeks on a high-fat diet (48kcal% fat), mice developed glucose intolerance, and the gastrocnemius muscle showed a decrease in insulin signaling and mitochondrial function, which was reversed after carnitine (100mg/kg/day) treatment by oral gavage for 2weeks. Swollen mitochondria with destroyed cristae were observed in the skeletal muscle of high-fat diet-fed mice but were not there after carnitine treatment. High-fat diet decreased LC3B-II, a marker of autophagosome formation, and increased sequestosome 1 (SQSTM1), expression of which was reversed after carnitine treatment. In C2C12 myotubes, prolonged treatment with palmitate suppressed autophagy, which was relieved by carnitine treatment. However, the induction of autophagy by carnitine in C2C12 myotubes was not observed after knock-down of peroxisome proliferator-activated receptor γ (PPARγ), which is known to regulate autophagy.

CONCLUSION

We conclude that the removal of dysfunctional mitochondria by induction of autophagy through PPARγ may be a novel mechanism by which carnitine improves insulin resistance and mitochondrial dysfunction in obesity.

High Concentrations of Rosiglitazone Reduce mRNA and Protein Levels of LRP1 in HepG2 Cells

Low-density lipoprotein receptor-related protein 1 (LRP1) is an endocytic receptor involved in the uptake of a variety of molecules, such as apoE, α2-macroglobulin, and the amyloid β peptide (Aβ), for either transcellular transport, protein trafficking or lysosomal degradation. The LRP1 gene can be transcribed upon activation of peroxisome proliferator receptor activated-γ (PPARγ) by the potent PPARγ agonist, rosiglitazone (RGZ). In previous studies, RGZ was shown to upregulate LRP1 levels in concentrations between 0.1 and 5 μM in HepG2 cells. In this study, we sought to replicate previous studies and to investigate the molecular mechanism by which high concentrations of RGZ reduce LRP1 levels in HepG2 cells. Our data confirmed that transcriptional activation of LRP1 occurred in response to RGZ at 3 and 10 μM, in agreement with the study reported by Moon et al. (2012a). On the other hand, we found that high concentrations of RGZ decreased both mRNA and protein levels of LRP1. Mechanistically, transcriptional dysregulation of LRP1 was affected by the downregulation of PPARγ in a time- and concentration-dependent manner. However, downregulation of PPARγ was responsible for only 40% of the LRP1 reduction and thereby the remaining loss of LRP1 (60%) was found to be through degradation in the lysosomal system. In conclusion, our findings demonstrate the mechanisms by which high concentrations of RGZ caused LRP1 levels to be reduced in HepG2 cells. Taken together, this data will be helpful to better explain the pharmacological modulation of this pivotal membrane receptor by PPARγ agonists.

The role of pparγ and autophagy in ros production, lipid droplets biogenesis and its involvement with colorectal cancer cells modulation

Background

In cancer cells, autophagy can act as both tumor suppressor, when autophagic event eliminates cellular contends which exceeds the cellular capacity of regenerate promoting cell death, and as a pro-survival agent removing defective organelles and proteins and helping well-established tumors to maintain an accelerated metabolic state while still dealing with harsh conditions, such as inflammation. Many pathways can coordinate the autophagic process and one of them involves the transcription factors called PPARs, which also regulate cellular differentiation, proliferation and survival. The PPARγ activation and autophagy initiation seems to be interrelated in a variety of cell types.

Methods

Caco-2 cells were submitted to treatment with autophagy and PPARγ modulators and the relationship between both pathways was determined by western blotting and confocal microscopy. The effects of such modulations on Caco-2 cells, such as lipid bodies biogenesis, cell death, proliferation, cell cycle, ROS production and cancer stem cells profiling were analyzed by flow cytometry.

Results

PPARγ and autophagy pathways seem to be overlap in Caco-2 cells, modulating each other in different ways and determining the lipid bodies biogenesis. In general, inhibition of autophagy by 3-MA leaded to reduced cell proliferation, cell cycle arrest and, ultimately, cell death by apoptosis. In agreement with these results, ROS production was increased in 3-MA treated cells. Autophagy also seems to play an important role in cancer stem cells profiling. Rapamycin and 3-MA induced epithelial and mesenchymal phenotypes, respectively.

Conclusions

This study helps to elucidate in which way the induction or inhibition of these pathways regulate each other and affect cellular properties, such as ROS production, lipid bodies biogenesis and cell survive. We also consolidate autophagy as a key factor for colorectal cancer cells survival in vitro, pointing out a potential side effect of autophagic inhibition as a therapeutic application for this disease and demonstrate a novel regulation of PPARγ expression by inhibition of PI3K III.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-017-0451-5) contains supplementary material, which is available to authorized users.

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

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

Reciprocal Crosstalk Between Autophagic and Endocrine Signaling in Metabolic Homeostasis

Autophagy is a cellular quality control and energy-providing process that is under strict control by intra- and extracellular stimuli. Recently, there has been an exponential increase in autophagy research and its implications for mammalian physiology. Autophagy deregulation is now being implicated in many human diseases, and its modulation has shown promising results in several preclinical studies. However, despite the initial discovery of autophagy as a hormone-regulated process by De Duve in the early 1960s, endocrine regulation of autophagy still remains poorly understood. In this review, we provide a critical summary of our present understanding of the basic mechanism of autophagy, its regulation by endocrine hormones, and its contribution to endocrine and metabolic homeostasis under physiological and pathological settings. Understanding the cross-regulation of hormones and autophagy on endocrine cell signaling and function will provide new insight into mammalian physiology as well as promote the development of new therapeutic strategies involving modulation of autophagy in endocrine and metabolic disorders.

PPAR-γ Agonists As Antineoplastic Agents in Cancers with Dysregulated IGF Axis

It is now widely accepted that insulin resistance and compensatory hyperinsulinemia are associated to increased cancer incidence and mortality. Moreover, cancer development and progression as well as cancer resistance to traditional anticancer therapies are often linked to a deregulation/overactivation of the insulin-like growth factor (IGF) axis, which involves the autocrine/paracrine production of IGFs (IGF-I and IGF-II) and overexpression of their cognate receptors [IGF-I receptor, IGF-insulin receptor (IR), and IR]. Recently, new drugs targeting various IGF axis components have been developed. However, these drugs have several limitations including the occurrence of insulin resistance and compensatory hyperinsulinemia, which, in turn, may affect cancer cell growth and survival. Therefore, new therapeutic approaches are needed. In this regard, the pleiotropic effects of peroxisome proliferator activated receptor (PPAR)-γ agonists may have promising applications in cancer prevention and therapy. Indeed, activation of PPAR-γ by thiazolidinediones (TZDs) or other agonists may inhibit cell growth and proliferation by lowering circulating insulin and affecting key pathways of the Insulin/IGF axis, such as PI3K/mTOR, MAPK, and GSK3-β/Wnt/β-catenin cascades, which regulate cancer cell survival, cell reprogramming, and differentiation. In light of these evidences, TZDs and other PPAR-γ agonists may be exploited as potential preventive and therapeutic agents in tumors addicted to the activation of IGF axis or occurring in hyperinsulinemic patients. Unfortunately, clinical trials using PPAR-γ agonists as antineoplastic agents have reached conflicting results, possibly because they have not selected tumors with overactivated insulin/IGF-I axis or occurring in hyperinsulinemic patients. In conclusion, the use of PPAR-γ agonists in combined therapies of IGF-driven malignancies looks promising but requires future developments.

Study of novel anticancer 4-thiazolidinone derivatives

4-Thiazolidinones are a known class of prospective drug-like molecules, especially in the design of new anticancer agents. Two of the most prominent subtypes of these compounds are 5-ene-2-amino(amino)-4-thiazolidinones and thiopyrano[2,3-d]thiazoles. The latter are considered to be cyclic mimetics of biologically active 5-ene-4-thiazolidinones with similar pharmacological profiles. Therefore, the aim of this study was to evaluate the impact of 4-thiazolidinone-based compounds on cytotoxicity, the apoptotic process, and metabolism in the human squamous carcinoma (SCC-15) cell line. The SCC-15 cells were cultured in phenol red-free DMEM/F12 medium supplemented with 10% FBS, hydrocortisone, and exposed to rising concentrations (1 nM-100 μM) of the studied compounds for 6, 24 and 48 h. Afterwards, reactive oxygen species (ROS) formation, cell viability, caspase-3 activity, and cell metabolism were measured. The obtained results showed that all of the studied compounds in a wide range of concentrations (1 nM-100 μM) increased DCF fluorescence which suggests a stimulation of ROS production. Nevertheless, these new compounds showed cytotoxic and proapoptotic properties only at high (10-100 μM) concentrations. Our studies are the first to be carried out on these compounds and require further investigation to clarify the mechanism of action of their anticancer potential.

Taurine protects against As2O3-induced autophagy in livers of rat offsprings through PPARγ pathway

Chronic exposures to arsenic had been associated with metabolism diseases. Peroxisome proliferator-activated receptor gamma (PPARγ) was found in the liver, regulated metabolism. Here, we found that the expression of PPARγ was decreased, the generation of reactive oxygen species (ROS) and autophagy were increased after treatment with As₂O₃ in offsprings’ livers. Taurine (Tau), a sulfur-containing β–amino acid could reverse As₂O₃-inhibited PPARγ. Tau also inhibit the generation of ROS and autophagy. We also found that As₂O₃ caused autophagic cell death and ROS accelerated in HepG2 cells. Before incubation with As₂O₃, the cells were pretreated with PPARγ activator Rosiglitazone (RGS), we found that autophagy and ROS was inhibited in HepG2 cells, suggesting that inhibition of PPARγ contributed to As₂O₃-induced autophagy and the generation of ROS. After pretreatment with Tau, the level of PPARγ was improved and the autophagy and ROS was inhibited in As₂O₃-treated cells, suggesting that Tau could protect hepatocytes against As₂O₃ through modulating PPARγ pathway.

Chloroquine enhances the efficacy of cisplatin by suppressing autophagy in human adrenocortical carcinoma treatment

BACKGROUND

It has been demonstrated that chloroquine (CQ) enhances the efficacy of chemotherapy. However, little is known about whether CQ could enhance the efficacy of cisplatin (DDP) in the treatment of adrenocortical carcinoma (ACC). In this study, we explore the efficacy and mechanism by which CQ affects DDP sensitivity in human ACC in vitro and in vivo.

METHODS

The autophagic gene Beclin-1 expression was detected by immunohistochemistry, and the protein levels were analyzed using immunoblotting assays of ACC tissues and normal adrenal cortex tissues. The ACC SW13 cells were treated with DDP and/or CQ. The cell viability assay was performed using the MTT method. Qualitative autophagy detection was performed by monodansylcadaverine staining of autophagic vacuoles. Annexin V-fluorescein isothiocyanate/propidium iodide double staining was used to count cell apoptosis by flow cytometry. The autophagy-related protein (Beclin-1, LC3, and p62) and apoptosis relative protein (Bax and Bcl-2) levels were evaluated with Western blot analysis. Furthermore, a murine model of nude BALB/c mice bearing SW13 cell xenografts was established to evaluate the efficacy of concomitant therapy.

RESULTS

The expression of the autophagic gene Beclin-1 was significantly downregulated in ACC tissues compared to normal adrenal cortex tissues. The Beclin-1 protein level in ACC tissues was lower than that in normal adrenal cortex tissues (P<0.05). In vitro concomitant therapy (DDP and CQ) was more effective in restraining SW13 cell proliferation. DDP could promote cell apoptosis and induce autophagy in SW13 cells. Concomitant therapy further promoted cell apoptosis by inhibiting autophagy. In vivo, we found that concomitant therapy was more potent than DDP monotherapy in inhibiting the growth of xenografted tumors and prolonging the survival of tumor-bearing mice.

CONCLUSION

The antitumor ability of DDP was related to autophagy activity, and the concomitant therapy (DDP and CQ) could be an optimal strategy for treating ACC.

BNIP3 is essential for mitochondrial bioenergetics during adipocyte remodelling in mice

AIMS/HYPOTHESIS

Adipose tissue is a highly versatile system in which mitochondria in adipocytes undergo significant changes during active tissue remodelling. BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3) is a mitochondrial protein and a known mitochondrial quality regulator. In this study, we investigated the role of BNIP3 in adipocytes, specifically under conditions of peroxisome proliferator-activated receptor-γ (PPARγ)-induced adipose tissue remodelling.

METHODS

The expression of BNIP3 was evaluated in 3T3-L1 adipocytes in vitro, C57BL/6 mice fed a high-fat diet and db/db mice in vivo. Mitochondrial bioenergetics was investigated in BNIP3-knockdown adipocytes after rosiglitazone treatment. A putative peroxisome proliferator hormone responsive element (PPRE) was characterised by promoter assay and electrophoretic mobility shift assay (EMSA).

RESULTS

The protein BNIP3 was more abundant in brown adipose tissue than white adipose tissue. Furthermore, BNIP3 expression was upregulated by 3T3-L1 pre-adipocyte differentiation, starvation and rosiglitazone treatment. Conversely, BNIP3 expression in adipocytes decreased under various conditions associated with insulin resistance. This downregulation of BNIP3 was restored by rosiglitazone treatment. Knockdown of BNIP3 in adipocytes inhibited rosiglitazone-induced mitochondrial biogenesis and function, partially mediated by the 5' AMP-activated protein kinase (AMPK)-peroxisome proliferator-activated receptor γ, co-activator 1 α (PGC1α) signalling pathway. Rosiglitazone treatment increased the transcription level of Bnip3 in the reporter assay and the presence of the PPRE site in the Bnip3 promoter was demonstrated by EMSA.

CONCLUSIONS/INTERPRETATION

The protein BNIP3 contributes to the improvement of mitochondrial bioenergetics that occurs on exposure to rosiglitazone. It may be a novel therapeutic target for restoring mitochondrial dysfunction under insulin-resistant conditions.

Autophagy in endocrine tumors

Autophagy is an important intracellular process involving the degradation of cytoplasmic components. It is involved in both physiological and pathological conditions, including cancer. The role of autophagy in cancer is described as a 'double-edged sword,' a term that reflects its known participation in tumor suppression, tumor survival and tumor cell proliferation. Available research regarding autophagy in endocrine cancer supports this concept. Autophagy shows promise as a novel therapeutic target in different types of endocrine cancer, inhibiting or increasing treatment efficacy in a context- and cell-type-dependent manner. At present, however, there is very little research concerning autophagy in endocrine tumors. No research was reported connecting autophagy to some of the tumors of the endocrine glands such as the pancreas and ovary. This review aims to elucidate the roles of autophagy in different types of endocrine cancer and highlight the need for increased research in the field.

Emerging therapy for adrenocortical carcinoma

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

Energy restriction mimetic agents to target cancer cells: comparison between 2-deoxyglucose and thiazolidinediones

The use of energy restriction mimetic agents (ERMAs) to selectively target cancer cells addicted to glycolysis could be a promising therapeutic approach. Thiazolidinediones (TZDs) are synthetic agonists of the nuclear receptor peroxisome proliferator-activated receptor (PPAR)γ that were developed to treat type II diabetes. These compounds also display anticancer effects which appear mainly to be independent of their PPARγ agonist activity but the molecular mechanisms involved in the anticancer action are not yet well understood. Results obtained on ciglitazone derivatives, mainly in prostate cancer cell models, suggest that these compounds could act as ERMAs. In the present paper, we introduce how compounds like 2-deoxyglucose target the Warburg effect and then we discuss the possibility that the PPARγ-independent effects of various TZD could result from their action as ERMAs.

Proteasome inhibitors activate autophagy involving inhibition of PI3K-Akt-mTOR pathway as an anti-oxidation defense in human RPE cells

The two major intracellular protein degradation systems, the ubiquitin-proteasome system (UPS) and autophagy, work collaboratively in many biological processes including development, apoptosis, aging, and countering oxidative injuries. We report here that, in human retinal pigment epithelial cells (RPE), ARPE-19 cells, proteasome inhibitors, clasto-lactacystinβ-lactone (LA) or epoxomicin (Epo), at non-lethal doses, increased the protein levels of autophagy-specific genes Atg5 and Atg7 and enhanced the conversion of microtubule-associated protein light chain (LC3) from LC3-I to its lipidative form, LC3-II, which was enhanced by co-addition of the saturated concentration of Bafilomycin A1 (Baf). Detection of co-localization for LC3 staining and labeled-lysosome further confirmed autophagic flux induced by LA or Epo. LA or Epo reduced the phosphorylation of the protein kinase B (Akt), a downstream target of phosphatidylinositol-3-kinases (PI3K), and mammalian target of rapamycin (mTOR) in ARPE-19 cells; by contrast, the induced changes of autophagy substrate, p62, showed biphasic pattern. The autophagy inhibitor, Baf, attenuated the reduction in oxidative injury conferred by treatment with low doses of LA and Epo in ARPE-19 cells exposed to menadione (VK3) or 4-hydroxynonenal (4-HNE). Knockdown of Atg7 with siRNA in ARPE-19 cells reduced the protective effects of LA or Epo against VK3. Overall, our results suggest that treatment with low levels of proteasome inhibitors confers resistance to oxidative injury by a pathway involving inhibition of the PI3K-Akt-mTOR pathway and activation of autophagy.

PPARγ-dependent pathway in the growth-inhibitory effects of K562 cells by carotenoids in combination with rosiglitazone

BACKGROUND

Carotenoids have been found to play roles in the prevention and therapy of some cancers which PPARγ was also discovered to be involved in. The present studies were directed to determine the inhibitory effects of carotenoids in combination with rosiglitazone, a synthetic PPARγ agonist, on K562 cell proliferation and elucidate the contribution of PPARγ-dependent pathway to cell proliferation suppression.

METHODS

The effects of carotenoid and rosiglitazone combination on K562 cell proliferation were evaluated by trypan blue dye exclusion assay and MTT assay. When PPARγ has been inhibited by GW9662 and siRNA, cycle-related regulator expression in K562 cells treated with carotenoid and rosiglitazone combination was analyzed by Western blotting.

RESULTS

Rosiglitazone inhibited K562 cell proliferation and augmented the inhibitory effects of carotenoids on the cell proliferation greatly. Specific PPARγ inhibition attenuated the cell growth suppression induced by carotenoid and rosiglitazone combination. GW9662 pre-treatment attenuated the enhanced up-regulation of PPARγ expression caused by the combination treatment. Moreover, GW9662 and PPARγ siRNA also significantly attenuated the up-regulation of p21 and down-regulation of cyclin D1 caused by carotenoids and rosiglitazone.

CONCLUSIONS

PPARγ signaling pathway, via stimulating p21 and inhibiting cyclin D1, may play an important role in the anti-proliferative effects of carotenoid and rosiglitazone combination on K562 cells.

GENERAL SIGNIFICANCE

Carotenoids in combination with rosiglitazone are hopeful to provide attractive dietary or supplementation-based and pharmaceutical strategies to treat cancer diseases.

Effects of rosiglitazone on the growth and lymphangiogenesis of human gastric cancer transplanted in nude mice

Gastric cancer mainly metastasizes via lymphatic vessels. Thus, it is critical to identify efficacious chemopreventive agents for lymphangiogenesis. The present study was undertaken to explore the effects of rosiglitazone (ROSI) on the growth and lymphangiogenesis of human gastric cancer. We established a model of gastric cancer by subcutaneously inoculating the human gastric cancer cell line SGC-7901 into nude mice. Mice were randomly divided into 4 groups and each group received a different agent by oral gavage. The control group received normal saline and treatment groups received different doses of ROSI once every 2 days. The growth of the tumor in vivo was assessed by measuring tumor volume. After 42 days, the mice were sacrificed and the tumors were removed. H&E staining was used to observe the histomorphological features; immunohistochemistry staining for lymphatic vessel density (LVD) was used to evaluate tumor lymphangiogenesis, RT-PCR was performed to determine the mRNA expression of vascular endothelial growth factor C (VEGF-C) and VEGF receptor-3 (VEGFR-3), and western blotting was used to detect the protein expression of VEGF-C and VEGFR-3. Compared with the control group, all treatment groups had smaller tumor volume and higher tumor growth inhibitory rate every day. The number of typical tumor cells in the control group was higher compared to that in the treatment groups, and the highest level of LVD was found in the control group. Furthermore, both the expression of VEGF-C and VEGFR-3 mRNA and proteins in the control group were significantly higher compared to those in the treatment groups. Markedly, these changes were correlated in a dose-dependent manner with ROSI. These results demonstrated that, through simultaneously blocking the expression of VEGF-C and VEGFR-3, ROSI suppresses lymphangiogenesis. This may represent a powerful therapeutic approach for controlling gastric cancer cell growth and metastasis.

Rosiglitazone protects against palmitate-induced pancreatic beta-cell death by activation of autophagy via 5'-AMP-activated protein kinase modulation

Promoting beta-cell survival is crucial for the prevention of beta-cell failure in diabetes. Thiazolidinediones, a widely used drug to improve insulin sensitivity in clinical practice, is found to have a protective effect on islet beta-cell. To date, the mechanism underlying the protective role of thiazolidinedione on beta-cell survival remain largely unknown. Activation of autophagy was detected by transmission electron microscopy, western blot, and GFP-LC3 transfection. Cell viability was examined by WST-8. Cell apoptosis was demonstrated by DAPI and Annexin V/PI staining. Colony formation assay was used to detect long-term cell viability. We demonstrated that rosiglitazone-treated beta-cells were more resistant to palmitate-induced apoptosis. The conversion of LC3-I to LC3-II and accumulated autophagosomes were found to be upregulated in rosiglitazone-treated cells. Inhibition of autophagy augmented palmitate-induced apoptosis with rosiglitazone treatment, suggesting that autophagy plays an important role in the survival function of rosiglitazone on beta-cells. Furthermore, we showed that rosiglitazone could induce AMP-activated protein kinase (AMPK) phosphorylation and reduce p70S6 kinase phosphorylation. Inhibition of AMPK impaired autophagy activation and enhanced palmitate-induced apoptosis during rosiglitazone treatment. These findings reveal that rosiglitazone-induced autophagy contributes to its protective function on beta-cells during palmitate treatment.

Compartment-specific activation of PPARγ governs breast cancer tumor growth, via metabolic reprogramming and symbiosis

The role of PPARγ in cancer therapy is controversial, with studies showing either pro-tumorigenic or antineoplastic effects. This debate is very clinically relevant, because PPARγ agonists are used as antidiabetic drugs. Here, we evaluated if the effects of PPARγ on tumorigenesis are determined by the cell type in which PPARγ is activated. Second, we examined if the metabolic changes induced by PPARγ, such as glycolysis and autophagy, play any role in the tumorigenic process. To this end, PPARγ was overexpressed in breast cancer cells or in stromal cells. PPARγ-overexpressing cells were examined with respect to (1) their tumorigenic potential, using xenograft models, and (2) regarding their metabolic features. In xenograft models, we show that when PPARγ is activated in cancer cells, tumor growth is inhibited by 40%. However, when PPARγ is activated in stromal cells, the growth of co-injected breast cancer cells is enhanced by 60%. Thus, the effect(s) of PPARγ on tumorigenesis are dependent on the cell compartment in which PPARγ is activated. Mechanistically, stromal cells with activated PPARγ display metabolic features of cancer-associated fibroblasts, with increased autophagy, glycolysis and senescence. Indeed, fibroblasts overexpressing PPARγ show increased expression of autophagic markers, increased numbers of acidic autophagic vacuoles, increased production of L-lactate, cell hypertrophy and mitochondrial dysfunction. In addition, PPARγ fibroblasts show increased expression of CDKs (p16/p21) and β-galactosidase, which are markers of cell cycle arrest and senescence. Finally, PPARγ induces the activation of the two major transcription factors that promote autophagy and glycolysis, i.e., HIF-1α and NFκB, in stromal cells. Thus, PPARγ activation in stromal cells results in the formation of a catabolic pro-inflammatory microenvironment that metabolically supports cancer growth. Interestingly, the tumor inhibition observed when PPARγ is expressed in epithelial cancer cells is also associated with increased autophagy, suggesting that activation of an autophagic program has both pro- or antitumorigenic effects depending on the cell compartment in which it occurs. Finally, when PPARγ is expressed in epithelial cancer cells, the suppression of tumor growth is associated with a modest inhibition of angiogenesis. In conclusion, these data support the "two-compartment tumor metabolism" model, which proposes that metabolic coupling exists between catabolic stromal cells and oxidative cancer cells. Cancer cells induce autophagy, glycolysis and senescence in stromal cells. In return, stromal cells generate onco-metabolites and mitochondrial fuels (L-lactate, ketones, glutamine/aminoacids and fatty acids) that are used by cancer cells to enhance their tumorigenic potential. Thus, as researchers design new therapies, they must be conscious that cancer is not a cell-autonomous disease, but rather a tumor is an ecosystem of many different cell types, which engage in metabolic symbiosis.

Oncophagy: harnessing regulation of autophagy in cancer therapy

Autophagy is an increasingly well-characterised process of cell component auto-digestion and recycling thought necessary for cellular subsistence. As we gain a more thorough understanding of the mechanisms underlying autophagy, its relevance to human disease and therapeutic potential are being clarified. This review summarises the evidence implicating autophagy in the pathogenesis and potential treatment of malignant disease. In addition, we explore the molecular role of microRNAs as key regulators in what we propose should now become known as 'oncophagy'.

Current and emerging therapeutic options in adrenocortical cancer treatment

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

The next generation of therapies for adrenocortical cancers

Adrenocortical carcinoma (ACC) is a rare cancer for which few treatment options have been available. Currently, the best available treatment involves combination chemotherapy with the adrenolytic drug mitotane, although the response rate remains modest. Over the past 10 years there has been renewed interest in the field owing to the recognition that targeted therapies may provide new avenues for effective treatment of this deadly disease. Molecular analyses have revealed specific signaling alterations in ACC, and advances in drug development have generated the tools to block these pathways. Although convincing evidence for the effectiveness of targeted therapies is not currently available, these studies are in progress and should shift the prognosis of this disease in the years to come.

A peroxisome proliferator-activated receptor ligand MCC-555 imparts anti-proliferative response in pancreatic cancer cells by PPARgamma-independent up-regulation of KLF4

MCC-555 is a novel PPARα/γ dual ligand of the thiazolidinedione class and was recently developed as an anti-diabetic drug with unique properties. MCC-555 also has anti-proliferative activity through growth inhibition and apoptosis induction in several cancer cell types. Our group has shown that MCC-555 targets several proteins in colorectal tumorigenesis including nonsteroidal anti-inflammatory drug (NSAID)-activated gene (NAG-1) which plays an important role in chemoprevention responsible for chemopreventive compounds. NAG-1 is a member of the TGF-β superfamily and is involved in tumor progression and development; however, NAG-1's roles in pancreatic cancer have not been studied. In this report, we found that MCC-555 alters not only NAG-1 expression, but also p21 and cyclin D1 expression. NAG-1 and p21 expression was not blocked by PPARγ-specific antagonist GW9662, suggesting that MCC-555-induced NAG-1 and p21 expression is independent of PPARγ activation. However, decreasing cyclin D1 by MCC-555 seems to be affected by PPARγ activation. Further, we found that the GC box located in the NAG-1 promoter play an important role in NAG-1 transactivation by MCC-555. Subsequently, we screened several transcription factors that may bind to the GC box region in the NAG-1 promoter and found that KLF4 potentially binds to this region. Expression of KLF4 precedes NAG-1 and p21 expression in the presence of MCC-555, whereas blocking KLF4 expression using specific KLF4 siRNA showed that both NAG-1 and p21 expression by MCC-555 was blocked. In conclusion, MCC-555's actions on anti-proliferation involve both PPARγ-dependent and -independent pathways, thereby enhancing anti-tumorigenesis in pancreatic cancer cells.

Global Gene Expression Profiling in PPAR-γ Agonist-Treated Kidneys in an Orthologous Rat Model of Human Autosomal Recessive Polycystic Kidney Disease

Kidneys are enlarged by aberrant proliferation of tubule epithelial cells leading to the formation of numerous cysts, nephron loss, and interstitial fibrosis in polycystic kidney disease (PKD). Pioglitazone (PIO), a PPAR-γ agonist, decreased cell proliferation, interstitial fibrosis, and inflammation, and ameliorated PKD progression in PCK rats (Am. J. Physiol.-Renal, 2011). To explore genetic mechanisms involved, changes in global gene expression were analyzed. By Gene Set Enrichment Analysis of 30655 genes, 13 of the top 20 downregulated gene ontology biological process gene sets and six of the top 20 curated gene set canonical pathways identified to be downregulated by PIOtreatment were related to cell cycle and proliferation, including EGF, PDGF and JNK pathways. Their relevant pathways were identified using the Kyoto Encyclopedia of Gene and Genomes database. Stearoyl-coenzyme A desaturase 1 is a key enzyme in fatty acid metabolism found in the top 5 genes downregulated by PIO treatment. Immunohistochemical analysis revealed that the gene product of this enzyme was highly expressed in PCK kidneys and decreased by PIO. These data show that PIO alters the expression of genes involved in cell cycle progression, cell proliferation, and fatty acid metabolism.

A novel zebrafish human tumor xenograft model validated for anti-cancer drug screening

The development of a relatively simple, reliant and cost-effective animal test will greatly facilitate drug development. In this study, our goal was the establishment of a rapid, simple, sensitive and reproducible zebrafish xenograft model for anti-cancer drug screening. We optimized the conditions for the cancer cell xenograft in terms of injected cell numbers, incubation temperature and time. A range of human carcinoma cell types were stained with a fluorescent dye prior to injection into the fish larvae. Subsequent cancer cell dissemination was observed under fluorescent microscopy. Differences in injected cell numbers were reflected in the rate of dissemination from the xenograft site. Paclitaxel, known as a microtubule stabilizer, dose-dependently inhibited cancer cell dissemination in our zebrafish xenograft model. An anti-migratory drug, LY294002 (phosphatidylinositol 3-kinase inhibitor) also decreased the cancer cell dissemination. Chemical modifications to increase cancer drug pharmacokinetics, such as increased solubility (17-DMAG compared to geldanamycin) could also be assessed in our xenograft model. In addition to testing our new model using known anti-cancer drugs, we carried out further validation by screening a tagged triazine library. Two novel anti-cancer drug candidates were discovered. Therefore, our zebrafish xenograft model provides a vertebrate animal system for the rapid screening and pre-clinical testing of novel anti-cancer agents, prior to the requirement for testing in mammals. Our model system should greatly facilitate drug development for cancer therapy because of its speed, simplicity and reproducibility.

Human adrenocortical carcinoma cell lines

The human adrenal cortex secretes mineralocorticoids, glucocorticoids and adrenal androgens. These steroids are produced from unique cell types located within the three distinct zones of the adrenal cortex. Disruption of adrenal steroid production results in a variety of diseases that can lead to hypertension, metabolic syndrome, infertility and androgen excess. The adrenal cortex is also a common site for the development of adenomas, and rarely the site for the development of carcinomas. The adenomas can lead to diseases associated with adrenal steroid excess, while the carcinomas are particularly aggressive and have a poor prognosis. In vitro cell culture models provide important tools to examine molecular and cellular mechanisms controlling both the normal and pathologic function of the adrenal cortex. Herein, we discuss currently available human adrenocortical carcinoma cell lines and their use as model systems for adrenal studies.

Autophagy and disease: always two sides to a problem

Autophagy is a process traditionally known to contribute to cellular cleaning through the removal of intracellular components in lysosomes. In recent years, intensive scrutiny at the molecular level to which autophagy has been subjected has also contributed to expanding our understanding of the physiological role of this pathway. Added to the well-characterized role in quality control, autophagy has proved to be important in the maintenance of cellular homeostasis and of the energetic balance, in cellular and tissue remodelling, and cellular defence against extracellular insults and pathogens. It is not a surprise that, in light of this growing number of physiological functions, connections between autophagic malfunction and human pathologies have also been strengthened. In this review, we focus on several pathological conditions associated with primary or secondary defects in autophagy and comment on a recurring theme for many of them, ie the fact that autophagy can often exert both beneficial and aggravating effects on the progression of disease. Elucidating the factors that determine the switch between these dual functions of autophagy in disease has become a priority when considering the potential therapeutic implications of the pharmacological modulation of autophagy in many of these pathological conditions.