Downregulation of metastasis suppressor genes in malignant pheochromocytoma

D-allose, a typical rare sugar: properties, applications, and biosynthetic advances and challenges

D-allose, a C-3 epimer of D-glucose and an aldose-ketose isomer of D-allulose, exhibits 80% of sucrose's sweetness while being remarkably low in calories and nontoxic, making it an appealing sucrose substitute. Its diverse physiological functions, particularly potent anticancer and antitumor effects, render it a promising candidate for clinical treatment, garnering sustained attention. However, its limited availability in natural sources and the challenges associated with chemical synthesis necessitate exploring biosynthetic strategies to enhance production. This overview encapsulates recent advancements in D-allose's physicochemical properties, physiological functions, applications, and biosynthesis. It also briefly discusses the crucial role of understanding aldoketose isomerase structure and optimizing its performance in D-allose synthesis. Furthermore, it delves into the challenges and future perspectives in D-allose bioproduction. Early efforts focused on identifying and characterizing enzymes responsible for D-allose production, followed by detailed crystal structure analysis to improve performance through molecular modification. Strategies such as enzyme immobilization and implementing multi-enzyme cascade reactions, utilizing more cost-effective feedstocks, were explored. Despite progress, challenges remain, including the lack of efficient high-throughput screening methods for enzyme modification, the need for food-grade expression systems, the establishment of ordered substrate channels in multi-enzyme cascade reactions, and the development of downstream separation and purification processes.

Thiol-Based Antioxidants and the Epithelial/Mesenchymal Transition in Cancer

Significance: The epithelial/mesenchymal transition (EMT) is commonly associated with tumor metastasis. Oxidative and nitrosative stress is maintained in cancer cells and is involved in the EMT. Cancer cells are endowed with high levels of enzymatic and nonenzymatic antioxidants, which counteract the effects of oxidative and nitrosative stress. Thiol-based antioxidant systems such as the thioredoxin/thioredoxin reductase (Trx/TrxR) and glutathione/glutaredoxin (GSH/Grx) are continually active in cancer cells, while the thioredoxin-interacting protein (Txnip), the negative regulator of the Trx/TrxR system, is downregulated. Recent Advances: Trx/TrxR and GSH/Grx systems play a major role in maintaining EMT signaling and cancer cell progression. Critical Issues: Enhanced stress conditions stimulated in cancer cells inhibit EMT signaling. The elevated expression levels of the Trx/TrxR and GSH/Grx systems in these cells provide the antioxidant protection necessary to guarantee the occurrence of the EMT. Future Directions: Elevation of the intracellular reactive oxygen species and nitric oxide concentrations in cancer cells has been viewed as a promising strategy for elimination of these cells. The development of inhibitors of GSH synthesis and of the Trx/TrxR system together with genetic-based strategies to enhance Txnip levels may provide the necessary means to achieve this goal. Antioxid. Redox Signal. 36, 1037-1050.

BRMS1: a multifunctional signaling molecule in metastasis

Despite high mortality rates, molecular understanding of metastasis remains limited. It can be regulated by both pro- and anti-metastasis genes. The metastasis suppressor, breast cancer metastasis suppressor 1 (BRMS1), has been positively correlated with patient outcomes, but molecular functions are still being characterized. BRMS1 has been implicated in focal adhesion kinase (FAK), epidermal growth factor receptor (EGFR), and NF-κB signaling pathways. We review evidence that BRMS1 regulates these vast signaling pathways through chromatin remodeling as a member of mSin3 histone deacetylase complexes.

Genetic and epigenetic differences of benign and malignant pheochromocytomas and paragangliomas (PPGLs)

Pheochromocytomas and paragangliomas (PPGLs) are tumors arising from the adrenal medulla and sympathetic/parasympathetic paraganglia, respectively. According to Th e Cancer Genome Atlas (TCGA), approximately 40% of PPGLs are due to germ line mutations in one of 16 susceptibility genes, and a further 30% are due to somatic alterations in at least seven main genes (VHL, EPAS1, CSDE1, MAX, HRAS, NF1, RET, and possibly KIF1B). Th e diagnosis of malignant PPGL was straight forward in most cases as it was defined as presence of PPGL in non-chromaffin tissues. Accordingly, there is an extreme need for new diagnostic marker(s) to identify tumors with malignant prospective. Th e aim of this study was to review all suggested genetic and epigenetic alterations that are remarkably different between benign and malignant PPGLs. It seems that more than two genetic mutation clusters in PPGLs and other genetic and methylation biomarkers could be targeted for malignancy discrimination in different studies.

Emerging molecular markers of metastatic pheochromocytomas and paragangliomas

Metastatic pheochromocytoma/paraganglioma (PPGL) represents a major clinical challenge due to limitations in accurate diagnostic tools and effective treatments. Currently, patients classified at high-risk by means of clinical, biochemical and genetic criteria, require a lifelong monitoring, while it remains difficult to determine the metastatic potential of PPGL only on the basis of histopathological features. Thus, tumor molecular markers that improve the risk stratification of these patients are needed. In the past few years, we have witnessed an unprecedented molecular characterization of PPGL, which led to the emergence of promising candidate biomarkers predictive of metastatic behavior. Here, we briefly discuss these breakthroughs and provide some insights for the prospective implementation of molecular markers of metastatic PPGL in the clinical setting in years to come.

The Function of Thioredoxin-Binding Protein-2 (TBP-2) in Different Diseases

Thioredoxin-binding protein-2 (TBP-2) has an important role in the redox system, but it plays a different role in many different diseases (e.g., various cancers, diabetes mellitus (DM), cardiovascular disease, and cataracts) by influencing cell proliferation, differentiation, apoptosis, autophagy, and metabolism. Distinct transcription factors (TFs) stimulated by different factors combine with binding sites or proteins to upregulate or downregulate TBP-2 expression, in order to respond to the change in the internal environment. Most research disclosed that the main function of TBP-2 is associating with thioredoxin (Trx) to inhibit the antioxidant capacity of Trx. Furthermore, the TBP-2 located in tissues, whether normal or abnormal, has the ability to cause the dysfunctioning of cells and even death through different pathways, such as shortening the cell cycle and inducing apoptosis or autophagy. Through these studies, we found that TBP-2 promoted the development of diseases which are involved in inflammatory and oxidative damage. To a certain extent, we believe that there is some hidden connection between the biological functions which TBP-2 participates in and some distinct diseases. This review presents only a summary of the roles that TBP-2 plays in cancer, DM, cataracts, and so on, as well as its universal mechanisms. Further investigations are needed for the cell signaling pathways of the effects caused by TBP-2. A greater understanding of the mechanisms of TBP-2 could produce potential new targets for the treatment of diseases, including cancer and diabetes, cardiovascular disease, and cataracts.

A survey of metastasis suppressors in Metazoa

Metastasis suppressors are genes/proteins involved in regulation of one or more steps of the metastatic cascade while having little or no effect on tumor growth. The list of putative metastasis suppressors is constantly increasing although thorough understanding of their biochemical mechanism(s) and evolutionary history is still lacking. Little is known about tumor-related genes in invertebrates, especially non-bilaterians and unicellular relatives of animals. However, in the last few years we have been witnessing a growing interest in this subject since it has been shown that many disease-related genes are already present in simple non-bilateral animals and even in their unicellular relatives. Studying human diseases using simpler organisms that may better represent the ancestral conditions in which the specific disease-related genes appeared could provide better understanding of how those genes function. This review represents a compilation of published literature and our bioinformatics analysis to gain a general insight into the evolutionary history of metastasis-suppressor genes in animals (Metazoa). Our survey suggests that metastasis-suppressor genes emerged in three different periods in the evolution of Metazoa: before the origin of metazoans, with the emergence of first animals and at the origin of vertebrates.

A novel diagnostic method of Raman spectroscopy for malignant pheochromocytoma/paraganglioma

Raman spectroscopy, a potential tool in diagnosis of malignant pheochromocytoma/paraganglioma.

Breast Cancer Metastasis Suppressor 1 (BRMS1): Robust Biological and Pathological Data, But Still Enigmatic Mechanism of Action

Metastasis requires coordinated expression of multiple genetic cassettes, often via epigenetic regulation of gene transcription. BRMS1 blocks metastasis, but not orthotopic tumor growth in multiple tumor types, presumably via SIN3 chromatin remodeling complexes. Although there is an abundance of strong data supporting BRMS1 as a metastasis suppressor, the mechanistic data directly connecting molecular pathways with inhibition of particular steps in metastasis are not well defined. In this review, the data for BRMS1-mediated metastasis suppression in multiple tumor types are discussed along with the steps in metastasis that are inhibited.

The structural basis for the negative regulation of thioredoxin by thioredoxin-interacting protein

The redox-dependent inhibition of thioredoxin (TRX) by thioredoxin-interacting protein (TXNIP) plays a pivotal role in various cancers and metabolic syndromes. However, the molecular mechanism of this regulation is largely unknown. Here, we present the crystal structure of the TRX-TXNIP complex and demonstrate that the inhibition of TRX by TXNIP is mediated by an intermolecular disulphide interaction resulting from a novel disulphide bond-switching mechanism. Upon binding to TRX, TXNIP undergoes a structural rearrangement that involves switching of a head-to-tail interprotomer Cys63-Cys247 disulphide between TXNIP molecules to an interdomain Cys63-Cys190 disulphide, and the formation of a de novo intermolecular TXNIP Cys247-TRX Cys32 disulphide. This disulphide-switching event unexpectedly results in a domain arrangement of TXNIP that is entirely different from those of other arrestin family proteins. We further show that the intermolecular disulphide bond between TRX and TXNIP dissociates in the presence of high concentrations of reactive oxygen species. This study provides insight into TRX and TXNIP-dependent cellular regulation.

First molecular characterisation and expression analysis of a teleost thioredoxin-interacting protein (TXNIP) gene from rock bream (Oplegnathus fasciatus)

Thioredoxin-interacting protein (TXNIP) is an important regulator of glucose metabolism that functions by inhibiting cellular glucose uptake. The full-length rock bream (Oplegnathus fasciatus) TXNIP (RbTXNIP) cDNA (2499 bp) contains an open reading frame of 1188 bp encoding 396 amino acids. Furthermore, multiple alignments showed that the arrestin domain was well conserved among the other TXNIP sequences tested. RbTXNIP was predicted to contain a PxxP and PPxY motif. Phylogenetic analysis indicated that RbTXNIP is most closely related to Fugu rubripes TXNIP. RbTXNIP was expressed significantly in the RBC, intestine, and spleen. RbTXNIP mRNA expression was also examined in several tissues under conditions of bacterial and viral challenge. Generally, all tissues examined from fish infected with Streptococcus iniae, Edwardsiella tarda and red sea bream iridovirus (RSIV) showed significant downregulation in RbTXNIP expression compared to controls. However, RbTXNIP expression showed significant upregulation in the spleen and kidney after injection of recombinant rock bream TRx1 protein. These findings provide a molecular foundation for functional studies and applications in teleosts.

Estrogen stimulates the invasion of ovarian cancer cells via activation of the PI3K/AKT pathway and regulation of its downstream targets E‑cadherin and α‑actinin‑4

Previous studies by our group revealed that the phosphoinositide 3‑kinase (PI3K)/AKT pathway was involved in estrogen‑induced metastasis in ovarian cancer cells. In the present study, the role and mechanism of estrogen‑induced invasion was further explored using a stable short hairpin RNA (shRNA) estrogen receptor α/β (ER α/β) SKOV3 cell line when ER α and ER β were knocked down by lentiviral infection. The effects of estrogen and LY294002, a PI3K inhibitor, on the invasion of shRNA ER α/β SKOV3 cells were evaluated in vitro and in vivo. 17‑β estradiol promoted cell invasion, activated phosphorylated AKT in a dose‑ and time‑dependent manner, decreased E‑cadherin and increased cytoplasmic α‑actinin‑4 expression. When the PI3K/AKT pathway was suppressed by LY294002, the effect of estrogen was attenuated. Estrogen stimulated the growth of shRNA ER α/β SKOV3 xenograft tumors in nude mice, whereas LY294002 inhibited the growth and antagonized the effect of estrogen. The results indicate that estrogen promotes the invasion of ovarian cancer cells via activation of the PI3K/AKT pathway, downregulation of E‑cadherin and upregulation of α‑actinin‑4 in an ER‑independent manner. Inhibiting the PI3K/AKT pathway may be a useful treatment for ovarian carcinoma.

Effects of D-allose in combination with docetaxel in human head and neck cancer cells

In this study we investigated the combined effects of docetaxel and d-allose in HSC3 human oral carcinoma cells. The dose enhancement ratios at the 25% survival level were 1.3 and 1.71 for combined treatment with 10 or 25 mM D-allose, respectively. Apoptosis was significantly increased by addition of D-allose. Additionally, a synchronous increase in the G(2)/M-phase population was observed after docetaxel plus D-allose treatment. In vivo experiments revealed that docetaxel plus D-allose was more effective than either agent alone. Thus, D-allose enhanced the anticancer effects of docetaxel, and combined treatment may be useful to achieve clinical efficacy with reduced toxicity.

Thioredoxin/Txnip: redoxisome, as a redox switch for the pathogenesis of diseases

During the past few decades, it has been widely recognized that Reduction-Oxidation (redox) responses occurring at the intra- and extra-cellular levels are one of most important biological phenomena and dysregulated redox responses are involved in the initiation and progression of multiple diseases. Thioredoxin1 (Trx1) and Thioredoxin2 (Trx2), mainly located in the cytoplasm and mitochondria, respectively, are ubiquitously expressed in variety of cells and control cellular reactive oxygen species by reducing the disulfides into thiol groups. Thioredoxin interacting protein (Txnip/thioredoxin binding protein-2/vitamin D3 upregulated protein) directly binds to Trx1 and Trx2 (Trx) and inhibit the reducing activity of Trx through their disulfide exchange. Recent studies have revealed that Trx1 and Txnip are involved in some critical redox-dependent signal pathways including NLRP-3 inflammasome activation in a redox-dependent manner. Therefore, Trx/Txnip, a redox-sensitive signaling complex is a regulator of cellular redox status and has emerged as a key component in the link between redox regulation and the pathogenesis of diseases. Here, we review the novel functional concept of the redox-related protein complex, named “Redoxisome,” consisting of Trx/Txnip, as a critical regulator for intra- and extra-cellular redox signaling, involved in the pathogenesis of various diseases such as cancer, autoimmune disease, and diabetes.

Paragangliomas/Pheochromocytomas: clinically oriented genetic testing

Paragangliomas are rare neuroendocrine tumors that arise in the sympathetic or parasympathetic nervous system. Sympathetic paragangliomas are mainly found in the adrenal medulla (designated pheochromocytomas) but may also have a thoracic, abdominal, or pelvic localization. Parasympathetic paragangliomas are generally located at the head or neck. Knowledge concerning the familial forms of paragangliomas has greatly improved in recent years. Additionally to the genes involved in the classical syndromic forms: VHL gene (von Hippel-Lindau), RET gene (Multiple Endocrine Neoplasia type 2), and NF1 gene (Neurofibromatosis type 1), 10 novel genes have so far been implicated in the occurrence of paragangliomas/pheochromocytomas: SDHA, SDHB, SDHC, SDHD, SDHAF2, TMEM127, MAX, EGLN1, HIF2A, and KIF1B. It is currently accepted that about 35% of the paragangliomas cases are due to germline mutations in one of these genes. Furthermore, somatic mutations of RET, VHL, NF1, MAX, HIF2A, and H-RAS can also be detected. The identification of the mutation responsible for the paraganglioma/pheochromocytoma phenotype in a patient may be crucial in determining the treatment and allowing specific follow-up guidelines, ultimately leading to a better prognosis. Herein, we summarize the most relevant aspects regarding the genetics and clinical aspects of the syndromic and nonsyndromic forms of pheochromocytoma/paraganglioma aiming to provide an algorithm for genetic testing.

Involvement of Mediator complex in malignancy

Mediator complex (MED) is an evolutionarily conserved multiprotein, fundamental for growth and survival of all cells. In eukaryotes, the mRNA transcription is dependent on RNA polymerase II that is associated to various molecules like general transcription factors, MED subunits and chromatin regulators. To date, transcriptional machinery dysfunction has been shown to elicit broad effects on cell proliferation, development, differentiation, and pathologic disease induction, including cancer. Indeed, in malignant cells, the improper activation of specific genes is usually ascribed to aberrant transcription machinery. Here, we focus our attention on the correlation of MED subunits with carcinogenesis. To date, many subunits are mutated or display altered expression in human cancers. Particularly, the role of MED1, MED28, MED12, CDK8 and Cyclin C in cancer is well documented, although several studies have recently reported a possible association of other subunits with malignancy. Definitely, a major comprehension of the involvement of the whole complex in cancer may lead to the identification of MED subunits as novel diagnostic/prognostic tumour markers to be used in combination with imaging technique in clinical oncology, and to develop novel anti-cancer targets for molecular-targeted therapy.

Metastasis suppressors in breast cancers: mechanistic insights and clinical potential

For the most part, normal epithelial cells do not disseminate to other parts of the body and proliferate, as do metastatic cells. Presumably, a class of molecules-termed metastasis suppressors-are involved in this homeostatic control. Metastasis suppressors are, by definition, cellular factors that, when re-expressed in metastatic cells, functionally inhibit metastasis without significantly inhibiting tumor growth. In this brief review, we catalog known metastasis suppressors, what is known about their mechanism(s) of action, and experimental and clinical associations to date.

Expression of DNMTs and genomic DNA methylation in gastric signet ring cell carcinoma

The aim of the present study was to investigate the protein expression of DNA methyltransferases (DNMTs) and genomic DNA methylation status of genomes in gastric signet ring cell carcinoma (SRC). Immunohistochemistry was performed to analyze DNMT expression and methylated DNA immunoprecipitation microarray (MeDIP‑chip) and MeDIP quantitative real‑time PCR (MeDIP‑qPCR) were performed to analyze the genomic DNA methylation status in gastric SRC tissue. An increase in DNMT1 and decrease in DNMT3A expression in SRC tissue was observed compared with matched non‑cancerous tissue. However, expression of other DNMTs, DNMT2, DNMT3B and DNMT3L, was not found to differ significantly between carcinoma and control. The MeDIP‑chip assay revealed that methylation of gene promoters and CpG islands in SRC was higher than those in matched control tissue. However, MeDIP‑qPCR analysis demonstrated that specific tumor‑related genes, including ABL2, FGF18, TRAF2, EGFL7 and RAB33A were aberrantly hypomethylated in SRC tissue. Results of the current study indicate that gastric SRC may produce complex patterns of aberrant DNA methylation and DNMT expression.

The Kiss-1/Kiss-1R complex as a negative regulator of cell motility and cancer metastasis (Review)

Metastasis is a complex multistep process that involves the impairment of cell-cell adhesion in the neoplastic epithelium, invasion into adjacent tissues and the dissemination of cancer cells through the lymphatic and haematogenous routes. The inhibition of the metastatic process at an early stage has become a hot topic in cancer research. The Kiss-1 gene, initially described as a suppressor of metastasis in malignant melanoma, encodes the Kiss-1 protein which can be processed to other peptides, e.g., Kisspeptin-10, Kisspeptin-13, Kisspeptin-14 and Kisspeptin-54. These peptides are endogenous ligands of the Kiss‑1 receptor (Kiss-1R), a G protein-coupled receptor (GPR) also known as hOT7T175, AXOR12 or GPR54. The Kiss-1 gene has been suggested as a suppressor of metastasis in a various types of cancer, including gastric cancer, oesophageal carcinoma, pancreatic, ovarian, bladder and prostate cancer, through the regulation of cellular migration and invasion. In the current review, we summarise the current understanding of the role of Kiss‑1 and Kiss‑1R in cancer and cancer metastasis.

MDM2 binding protein, a novel metastasis suppressor

MDM2 binding protein (MTBP) is a protein that interacts with oncoprotein murine double minute (MDM2), a major inhibitor of the tumor suppressor p53. Overexpression of MTBP leads to p53-independent cell proliferation arrest, which is in turn blocked by simultaneous overexpression of MDM2. Importantly, reduced expression of MTBP in mice increases tumor metastasis and enhances migratory potential of mouse embryonic fibroblasts regardless of the presence of p53. Clinically, loss of MTBP expression in head and neck squamous cell carcinoma is associated with reduced patient survival, and is shown to serve as an independent prognostic factor when p53 is mutated in tumors. These results indicate the involvement of MTBP in suppressing tumor progression. Our recent findings demonstrate that overexpression of MTBP in human osteosarcoma cells lacking wild-type p53 inhibits metastasis, but not primary tumor growth, when cells are transplanted in femurs of immunocompromised mice. These data indicate that MTBP functions as a metastasis suppressor independent of p53 status. Furthermore, overexpression of MTBP suppresses cell migration and filopodia formation, in part, by inhibiting function of an actin crosslinking protein α-actinin-4. Thus, increasing evidence indicates the significance of MTBP in tumor progression. We summarize published results related to MTBP function and discuss caveats and future directions in this review article.

Thioredoxin and thioredoxin target proteins: from molecular mechanisms to functional significance

The thioredoxin (Trx) system is one of the central antioxidant systems in mammalian cells, maintaining a reducing environment by catalyzing electron flux from nicotinamide adenine dinucleotide phosphate through Trx reductase to Trx, which reduces its target proteins using highly conserved thiol groups. While the importance of protecting cells from the detrimental effects of reactive oxygen species is clear, decades of research in this field revealed that there is a network of redox-sensitive proteins forming redox-dependent signaling pathways that are crucial for fundamental cellular processes, including metabolism, proliferation, differentiation, migration, and apoptosis. Trx participates in signaling pathways interacting with different proteins to control their dynamic regulation of structure and function. In this review, we focus on Trx target proteins that are involved in redox-dependent signaling pathways. Specifically, Trx-dependent reductive enzymes that participate in classical redox reactions and redox-sensitive signaling molecules are discussed in greater detail. The latter are extensively discussed, as ongoing research unveils more and more details about the complex signaling networks of Trx-sensitive signaling molecules such as apoptosis signal-regulating kinase 1, Trx interacting protein, and phosphatase and tensin homolog, thus highlighting the potential direct and indirect impact of their redox-dependent interaction with Trx. Overall, the findings that are described here illustrate the importance and complexity of Trx-dependent, redox-sensitive signaling in the cell. Our increasing understanding of the components and mechanisms of these signaling pathways could lead to the identification of new potential targets for the treatment of diseases, including cancer and diabetes.

Expression of DNA-PKcs and BRCA1 as prognostic indicators in nasopharyngeal carcinoma following intensity-modulated radiation therapy

The mechanisms of radiation-induced effects in cancer mainly involve double-strand breaks (DSBs) which are important in maintaining the stability of genes. The DNA repair genes breast cancer 1 (BRCA1) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) are capable of maintaining genetic stability through two distinct and complementary repair mechanisms for DNA DSBs, known as repair-homologous recombination (HR) and non-homologous end joining (NHEJ). DNA-PKcs is a member of the phosphatidylinositol 3-kinase (PI3K) family. The PI3K/AKT cell signaling pathway is implicated in cell migration and invasion. The BRCA1 protein is implicated in multiple complex cellular processes that are related to chromosome sensitivity to mutagens. To determine the protein expression and clinical implications of DNA-PKcs and BRCA1 in nasopharyngeal carcinoma (NPC) and cancer progression, we evaluated its expression status by immunohistochemistry in 87 patients who received intensity-modulated radiation therapy (IMRT). In NPC, negative expression of DNA-PKcs was detected in 35 of the 87 (40.2%) cancer types and was significantly associated with poor patient survival (P<0.05). The overexpression of DNA-PKcs and BRCA1 also led to significantly improved distant metastasis-free survival compared with patients who did not overexpress both genes, although the expression level of BRCA1 and distant metastasis-free survival were not closely correlated. In addition, multivariate analysis indicated that DNA-PKcs status is a predictive marker of distant metastasis-free survival. In conclusion, lower expression of DNA-PKcs may be correlated with higher distant metastasis in patients with NPC. DNA-PKcs may be a predictive marker of distant metastasis after IMRT, independent of the classical prognostic marker. BRCA1 may additionally exert a synergistic effect to predict distant metastasis-free survival.

Sex steroids and the control of the Kiss1 system: developmental roles and major regulatory actions

Kisspeptins, encoded by the Kiss1 gene, and their canonical receptor, GPR54 (also termed Kiss1R), are unanimously recognised as essential regulators of puberty onset and gonadotrophin secretion. These key reproductive functions stem from the capacity of kisspeptins to stimulate gonadotrophin-releasing hormone (GnRH) secretion in the hypothalamus, where discrete populations of Kiss1 neurones have been identified. In rodents, two major groups of hypothalamic Kiss1 neurones exist: one present in the arcuate nucleus (ARC) and the other located in the anteroventral periventricular area (AVPV/RP3V). In recent years, numerous signals have been identified as putative modulators of the hypothalamic Kiss1 system. Among them, the prominent role of sex steroids as being important regulators of Kiss1 neurones has been documented in different species and developmental stages, such as early brain sex differentiation, puberty, adulthood and senescence. These regulatory actions are (mainly) conducted via oestrogen receptor (ER)α, which is expressed in almost all Kiss1 neurones, and likely involve both classical and nonclassical pathways. The regulatory effects of sex steroids are nucleus-specific. Thus, sex steroids inhibit the expression of Kiss1/kisspeptin at the ARC, as a mechanism to conduct their negative-feedback actions on gonadotrophin secretion. By contrast, oestrogens enhance Kiss1 expression at the AVPV/RP3V in rodents, suggesting the involvement of this population in the positive-feedback actions of oestradiol to generate the preovulatory surge of gonadotrophins. In addition, sex steroids have been shown to act post-transcriptionally, modulating GnRH/gonadotrophin responsiveness to kisspeptin. Finally, sex steroids also regulate the expression of co-transmitters of Kiss1 neurones, such as neurokinin B, whose mRNA content in the ARC fluctuates in parallel to that of Kiss1 in response to changes in the circulating levels of sex steroids, therefore suggesting the contribution of this neuropeptide in the feedback control of gonadotrophin secretion. In sum, compelling experimental evidence obtained in different mammalian (and non-mammalian) species, including primates, demonstrates that sex steroids are essential regulators of hypothalamic Kiss1 neurones, which in turn operate as conduits for their effects on GnRH neurones. The physiological relevance of such regulatory phenomena is thoroughly discussed.

Pheochromocytomas and paragangliomas: assessment of malignant potential

Pheochromocytomas and paragangliomas (PPGLs) are rare catecholamine-secreting tumors which arise from the adrenal glands or sympathetic neuronal tissue. Malignant transformation of these tumors occurs in a significant proportion and may therefore lower overall survival rates. In patients with PPGLs it is impossible to identify malignant disease without the presence of metastatic disease, something which can occur as long as 20 years after initial surgery. Early identification of malignant disease would necessitate a more aggressive treatment approach, something which may result in better disease outcome. We have therefore reviewed possible predictors of malignancy and current developments in order to help clinicians to swiftly assess malignant potential in patients with PPGLs. Currently, there is no absolute marker which can objectively reflect malignant potential. Tumor size is the most reliable predictor and should therefore be used as the baseline characteristic. The combination of various clinical markers (extra-adrenal disease and post-operative hypertension), biochemical markers (high dopamine, high norepinephrine and epinephrine to total catecholamine ratio) and/or histological markers (SNAIL, microRNAs and/or microarray results) can raise or lower the suspicion of malignancy. Furthermore, we discuss how clinical markers may affect biochemical results linked to malignancy, how biochemical results may distinguish hereditary syndromes, the role of imaging in determining malignant potential and tumor detection, and recent results of proposed histological markers.

Thioredoxin binding protein (TBP)-2/Txnip and α-arrestin proteins in cancer and diabetes mellitus

Thioredoxin binding protein -2/ thioredoxin interacting protein is an α-arrestin protein that has attracted much attention as a multifunctional regulator. Thioredoxin binding protein -2 expression is downregulated in tumor cells and the level of thioredoxin binding protein is correlated with clinical stage of cancer. Mice with mutations or knockout of the thioredoxin binding protein -2 gene are much more susceptible to carcinogenesis than wild-type mice, indicating a role for thioredoxin binding protein -2 in cancer suppression. Studies have also revealed roles for thioredoxin binding protein -2 in metabolic control. Enhancement of thioredoxin binding protein -2 expression causes impairment of insulin sensitivity and glucose-induced insulin secretion, and β-cell apoptosis. These changes are important characteristics of type 2 diabetes mellitus. Thioredoxin binding protein -2 regulates transcription of metabolic regulating genes. Thioredoxin binding protein -2-like inducible membrane protein/ arrestin domain containing 3 regulates endocytosis of receptors such as the β(2)-adrenergic receptor. The α-arrestin family possesses PPXY motifs and may function as an adaptor/scaffold for NEDD family ubiquitin ligases. Elucidation of the molecular mechanisms of α-arrestin proteins would provide a new pharmacological basis for developing approaches against cancer and type 2 diabetes mellitus.

Genetic and functional studies implicate HIF1α as a 14q kidney cancer suppressor gene

Kidney cancers often delete chromosome 3p, spanning the VHL tumor suppressor gene, and chromosome 14q, which presumably harbors ≥ 1 tumor suppressor genes. pVHL inhibits the hypoxia-inducible transcription factor (HIF), and HIF2α is a kidney cancer oncoprotein. In this article, we identify focal, homozygous deletions of the HIF1α locus on 14q in clear cell renal carcinoma cell lines. Wild-type HIF1α suppresses renal carcinoma growth, but the products of these altered loci do not. Conversely, downregulation of HIF1α in HIF1α-proficient lines promotes tumor growth. HIF1α activity is diminished in 14q-deleted kidney cancers, and all somatic HIF1α mutations identified in kidney cancers tested to date are loss of function. Therefore, HIF1α has the credentials of a kidney cancer suppressor gene.

SIGNIFICANCE

Deletion of 14q is a frequent event in clear cell renal carcinoma and portends a poor prognosis. In this study, we provide genetic and functional evidence that HIF1α is a target of 14q loss in kidney cancer.

Enhancement of the radiation effects by D-allose in head and neck cancer cells

The aim of this study was to investigate the radiosensitizing potential of D-allose in human head and neck cancer cells. HSC-3 cells were treated with or without D-allose for 6 h and then irradiated (2-6 Gy). The combination of D-allose and radiation was more effective than either agent alone. The radiation enhancement ratios at the 37% survival level were 1.61 and 2.11 for 10 mM and 25 mM D-allose treatment, respectively. The combination of D-allose and radiation also reduced the cell proliferation in 3D culture experiments. Although the mRNA expression of TXNIP was not increased by radiation alone, combined use with D-allose markedly elevated TXNIP expression. The combination of D-allose and radiation significantly induced intracellular reactive oxygen species (ROS) and apoptosis compared to that induced by either agent alone. This study shows that D-allose enhances the effect of radiation, suggesting a potential clinical application of combination treatment with D-allose and radiation for head and neck cancer.

Expression of galectin-3, nm-23, and cyclooxygenase-2 could potentially discriminate between benign and malignant pheochromocytoma

Currently, the only reliable indicator of malignancy in pheochromocytoma is the presence of distant metastasis or extensive local invasion; predicting behavior of pheochromocytoma remains challenging. We aimed to correlate the behavior of pheochromocytoma with its expression of nm-23, cyclooxygenase (COX)-2, and galectin-3 (genes used to predict the course of some neoplastic diseases), evaluated immunohistochemically in 55 paraffin blocks of formalin-fixed pheochromocytoma specimens with confirmed behavior. In 3 (7%) of 44 benign and 7 (64%) of 11 malignant pheochromocytomas, there was negative nm-23 expression (P = .000). COX-2 immunoreactivity was positive in 10 (23%) of benign and 9 (82%) of malignant tumors (P = .000). Galectin-3 was expressed in 5 (11%) of benign and 9 (82%) of malignant pheochromocytomas (P = .000). Negative nm-23, along with positive COX-2 or galectin-3, predicted malignancy with 100% specificity. Dual negativity for galectin-3 and COX-2, along with nm-23 positivity, indicated benign behavior with 100% sensitivity. In early pheochromocytoma, evaluation of nm-23, galectin-3, and COX-2 expression could predict the outcome. Larger studies seem necessary to confirm the potential practical value of our findings.

In vitro and in vivo effects of D-allose: up-regulation of thioredoxin-interacting protein in head and neck cancer cells

OBJECTIVES

This study was aimed to investigate the relationship between the antiproliferative effects of D-allose and the up-regulation of thioredoxin-interacting protein (TXNIP) in head and neck cancer cells.

METHODS

For the in vitro study, 5 oral squamous cell carcinoma cell lines (Ca9-22, HSC-3, HSC-4, SAS, and KON) were treated with 25 mmol/L D-allose. For the in vivo study, HSC-3 cells were used in a xenograft model with female athymic nude mice (BALB/c nu/nu; 5 to 6 weeks old).

RESULTS

Inhibition of cell growth by D-allose was noted in HSC-3 and Ca9-22 cells, along with significant induction of TXNIP. Although TXNIP up-regulation was also evident, albeit to a lesser extent, in the remaining cell lines, D-allose did not inhibit their growth. With the HSC-3 line, the cell survival fractions decreased and TXNIP expression increased in a D-allose dose-dependent manner. The antiproliferative effects were partially suppressed by concomitant D-glucose treatment, which also reduced TXNIP expression. In the in vivo experiment, the tumor volume at day 15 after D-allose treatment was reduced to 61% of that of the control group.

CONCLUSIONS

This study showed that D-allose exerts growth inhibitory effects on head and neck cancer cells in vitro and in vivo. The sugar may act as an antiproliferative agent via TXNIP induction and thus may be useful as a novel anticancer drug.

Malignant pheochromocytoma: a review

BACKGROUND

Pheochromocytomas are rare catecholamine-secreting tumors. Approximately 10 percent of pheochromocytomas are malignant. Traditionally, there has been no reliable method available to predict the malignant potential of pheochromocytoma. However, recent research has increased focus on differentiating at the time of surgery/diagnosis those pheochromocytoma tumors which have malignant potential. In this review, we discuss the current information known of malignant pheochromocytomas.

DATA SOURCES

The PubMed database was searched for articles on malignant pheochromocytoma published between 1993 and 2010.

CONCLUSIONS

The difficult task of predicting the malignant potential of a pheochromocytoma has yet to be answered definitively. However, all the studies presented give an idea of what we may look for in these tumors at the time of diagnosis. We have provided an algorithm based on the most current information known. A much larger study should be performed to test many of these theories with enough power to determine a standard of care.

The emerging role of the thioredoxin system in angiogenesis

Although there have been a multitude of studies, the mechanisms of angiogenesis remain incompletely understood. Increasing evidence suggests that cellular redox homeostasis is an important regulator of angiogenesis. The thioredoxin (TRX) system functions as an endogenous antioxidant that can exert influence over endothelial cell function via modulation of cellular redox status. It has become apparent that the cytosolic TRX1 isoform participates in both canonical and novel angiogenic signaling pathways and may represent an avenue for therapeutic exploitation. Recent studies have further identified a role for the mitochondrial isoform TRX2 in ischemia-induced angiogenesis. TRX-interacting protein (TXNIP) is the endogenous inhibitor of TRX redox activity that has been implicated in growth factor-mediated angiogenesis. As TXNIP is strongly induced by glucose, this molecule could be of consequence to disordered angiogenesis manifest in diabetes mellitus. This review will focus on data implicating the TRX system in endothelial cell homeostasis and angiogenesis.

Inhibition of histone deacetylase 10 induces thioredoxin-interacting protein and causes accumulation of reactive oxygen species in SNU-620 human gastric cancer cells

Histone deacetylase (HDAC)10, a novel class IIb histone deacetylase, is the most similar to HDAC6, since both contain a unique second catalytic domain. Unlike HDAC6, which is located in the cytoplasm, HDAC10 resides in both the nucleus and cytoplasm. The transcriptional targets of HDAC10 that are associated with HDAC10 gene regulation have not been identified. In the present study, we found that knockdown of HDAC10 significantly increased the mRNA expression levels of thioredoxin-interacting protein (TXNIP) in SNU-620 human gastric cancer cells; whereas inhibition of HDAC1, HDAC2, and HDAC6 did not affect TXNIP expression. TXNIP is the endogenous inhibitor of thioredoxin (TRX), which acts as a cellular antioxidant. Real-time PCR and immunoblot analysis confirmed that inhibition of HDAC10 induced TXNIP expression. Compared to class I only HDAC inhibitors, inhibitors targeting both class I and II upregulated TXNIP, indicating that TXNIP is regulated by class II HDACs such as HDAC10. We further verified that inhibition of HDAC10 induced release of cytochrome c and activated apoptotic signaling molecules through accumulation of reactive oxygen species (ROS). Taken together, our results demonstrate that HDAC10 is involved in transcriptional downregulation of TXNIP, leading to altered ROS signaling in human gastric cancer cells. How TXNIP is preferentially regulated by HDAC10 needs further investigation.

Regulation of embryonic kidney branching morphogenesis and glomerular development by KISS1 receptor (Gpr54) through NFAT2- and Sp1-mediated Bmp7 expression

G-protein-coupled receptor 54 (Gpr54, KISS1 receptor) plays critical roles in puberty regulation, tumor metastasis suppression, and vasoconstriction. Bone morphogenetic protein-7 (Bmp7) is required for kidney organogenesis. However, whether Gpr54 is involved in embryonic kidney development and how Bmp7 expression is regulated in the kidney are largely unknown. Here we report that Gpr54 deletion leads to kidney branching morphogenesis and glomerular development retardation in embryonic kidneys in vivo and in explanted kidneys in vitro. Gpr54 inactivation results in a high risk of low glomerular number in adult kidneys. Gpr54 is expressed in condensed mesenchyme at E12.5 and epithelial cells of proximal and distal tubules and collecting ducts at E17.5 and P0 mouse kidney. Deletion of Gpr54 decreases Bmp7 expression and Smad1 phosphorylation in the developing kidney. Using chromatin immunoprecipitation and luciferase assays, we demonstrate that Gpr54 regulates NFAT2- and Sp1-mediated Bmp7 transcription. Furthermore, we show that NFAT2 cooperates with Sp1 to promote Bmp7 transcription activation. Together, these data suggest that Gpr54 regulates Bmp7 expression through NFAT2 and Sp1 and plays an important role in embryonic kidney branching morphogenesis and glomerular development.

Kisspeptin-10, a KISS1-derived decapeptide, inhibits tumor angiogenesis by suppressing Sp1-mediated VEGF expression and FAK/Rho GTPase activation

Kisspeptin-10 (Kp-10), a decapeptide derived from the primary translation product of KISS1 gene, has been reported previously to be a key hormone for puberty and an inhibitor for tumor metastasis via the activation of G protein-coupled receptor 54. However, whether Kp-10 inhibits angiogenesis, which is critical for tumor growth and metastasis and other human diseases, is still unknown. Here we show that Kp-10 significantly inhibits human umbilical vein endothelial cell (HUVEC) migration, invasion, and tube formation, key processes in angiogenesis. Using chicken chorioallantoic membrane assay and vascular endothelial growth factor (VEGF)-induced mouse corneal micropocket assay, we show that Kp-10 inhibits angiogenesis in vivo. Furthermore, Kp-10 inhibits tumor growth in severe combined immunodeficient mice xenografted with human prostate cancer cells (PC-3) through inhibiting tumor angiogenesis, whereas Kp-10 has little effect on the proliferation of HUVECs and human prostate cancer cells. In deciphering the underlying molecular mechanisms, we show that Kp-10 suppresses VEGF expression by inhibiting the binding of specificity protein 1 to VEGF promoter and by blocking the activation of c-Src/focal adhesion kinase and Rac/Cdc42 signaling pathways in HUVECs, leading to the inhibition of tumor angiogenesis.

A shift from nuclear to cytoplasmic breast cancer metastasis suppressor 1 expression is associated with highly proliferative estrogen receptor-negative breast cancers

BACKGROUND/AIMS

To determine breast cancer metastasis suppressor 1 (BRMS1) expression in breast cancers and the efficacy of BRMS1 as a prognostic indicator, BRMS1 expression was assessed in two sets of breast cancer tissues.

METHODS

Epithelial cells from 36 frozen samples of breast cancers and corresponding normal breast were collected by laser capture microdissection and assessed for BRMS1 by quantitative RT-PCR and immunohistochemistry. BRMS1 was also evaluated by immunohistochemistry in a tissue microarray of 209 breast cancers and correlated with indicators of prognosis [estrogen receptor (ER), progesterone receptor (PR), ErbB2, p53, p27(Kip1), Bcl2 and Ki-67].

RESULTS

BRMS1 mRNA and protein were higher in 94 and 81%, respectively, of breast cancers than in corresponding normal epithelium. BRMS1 localization was predominantly nuclear, but 60-70% of cancers also exhibited cytoplasmic immunostaining. Breast cancers with lower nuclear than cytoplasmic BRMS1 (nuclear score - cytoplasmic score < or =0; 11% of cancers) had lower ER, lower PR and higher Ki-67 expression. There was also a trend toward poorer overall survival in this group of cancers, but this was only of borderline significance (p = 0.073). In Cox proportional hazards models, loss of nuclear BRMS1 was not a significant predictor of overall survival.

CONCLUSIONS

Loss of nuclear BRMS1 was associated with ER-negative cancers and a high rate of proliferation, but was not an independent indicator of prognosis.

DNA copy number variation and gene expression analyses reveal the implication of specific oncogenes and genes in GBM

To understand the pathogenesis of glioblastoma multiforme (GBM) we used high-resolution comparative genomic hybridization arrays and gene expression microarrays to identify DNA copy number alterations and gene expression changes in comparable sets of GBM samples. Gains were detected at chromosomes 1, 2, 7, 9, 12, 19, and 20 and losses at 6, 9, and 10. Gene expression analyses identified specific genes overexpressed in GBM mapping at amplified chromosomal regions. Among these genes we found genes involved in angiogenesis, extracellular matrix remodeling and several oncogenes. DNA copy number analysis along with gene expression profiles provides a powerful strategy to understand tumor progression and identification of genes involved in GBM pathogenesis.

Expression of the transcription factor snail and its target gene twist are associated with malignancy in pheochromocytomas

BACKGROUND

One of the best known functions of the zinc-finger transcription factor Snail is to induce epithelial-mesenchymal transition (EMT). Twist, a target genes of Snail, is known to promote the development of distant metastases in mice. Increasing evidence suggests that EMT plays a pivotal role in tumor progression and metastatic spread.

METHODS

Snail, Twist, and E-cadherin expression were assessed by immunohistochemistry and real-time quantitative reverse transcriptase-polymerase chain reaction in 12 malignant and 35 benign pheochromocytomas (PCC). Data were correlated with clinical characteristics and genetics.

RESULTS

We found Snail expression in 13 (28%) of 47 primary PCC samples. Twist was expressed in 31 (66%) of 47 cases. Only one of 47 PCC showed E-cadherin expression. We observed Snail expression in 7 (58%) of 12 malignant PCC, whereas only 6 (17%) of 35 apparently benign PCC revealed Snail expression (P = 0.01). Furthermore, 11 (92%) of 12 malignant PCC, but only 20 (57%) of 35 benign PCC, revealed Twist expression (P = 0.03). Interestingly, all five metastases showed Snail and Twist expression. In normal adrenal medulla, Snail, Twist, and E-cadherin expression could not be detected.

CONCLUSIONS

We describe for the first time that EMT markers Snail and Twist are expressed in PCC and that their expression is associated with malignancy. Our study supports a role for EMT in the malignant transformation of PCC.

Characterization of an animal model of aggressive metastatic pheochromocytoma linked to a specific gene signature

Pheochromocytomas are chromaffin cell-derived neuroendocrine tumors. There is presently no cure for metastatic pheochromocytoma and no reliable way to distinguish malignant from benign tumors before the development of metastases. In order to successfully manage pheochromocytoma, it is necessary to better understand the biological determinants of tumor behavior. For this purpose, we have recently established a mouse model of metastatic pheochromocytoma using tail vein injection of mouse pheochromocytoma (MPC) cells. We optimized this model modifying the number of cells injected, length of trypsin pre-treatment, and incubation temperature and duration for the MPC cells before injection, and by serial passage and re-selection of tumors exhibiting the metastatic phenotype. We evaluated the effect of these modifications on tumor growth using serial in vivo Magnetic Resonance Imaging studies. These results show that number of cells injected, the pre-injection incubation temperature, and duration of trypsin treatment are important factors to produce faster growing, more aggressive tumors that yielded secondary metastatic lesions. Serial harvest, culture and re-selection of metastatic liver lesions produced even more aggressive pheochromocytoma cells that retained their biochemical phenotype. Microarray gene expression comparison and quantitative real-time PCR of these more aggressive cells to the MPC-parental cell line identified genes that may be important for the metastatic process.

Genetic markers for the diagnosis and prognosis of pheochromocytoma

The last 5 years have witnessed important advances in understanding the mechanisms of tumorigenesis of chromaffin cells. Large-scale microarray analyses of pheochromocytomas have identified two distinct gene-expression profiles encompassing all hereditary and sporadic tumors. Gene-expression profiling of benign and malignant pheochromocytomas is providing a better understanding of the mechanisms of metastasis. Such studies hold promise for the development of new prognostic markers for early detection of malignant pheochromocytoma and for the identification of novel targets for therapeutic intervention.

Comprehensive dissection of PDGF-PDGFR signaling pathways in PDGFR genetically defined cells

Despite the growing understanding of PDGF signaling, studies of PDGF function have encountered two major obstacles: the functional redundancy of PDGFRα and PDGFRβ in vitro and their distinct roles in vivo. Here we used wild-type mouse embryonic fibroblasts (MEF), MEF null for either PDGFRα, β, or both to dissect PDGF-PDGFR signaling pathways. These four PDGFR genetically defined cells provided us a platform to study the relative contributions of the pathways triggered by the two PDGF receptors. They were treated with PDGF-BB and analyzed for differential gene expression, in vitro proliferation and differential response to pharmacological effects. No genes were differentially expressed in the double null cells, suggesting minimal receptor-independent signaling. Protean differentiation and proliferation pathways are commonly regulated by PDGFRα, PDGFRβ and PDGFRα/β while each receptor is also responsible for regulating unique signaling pathways. Furthermore, some signaling is solely modulated through heterodimeric PDGFRα/β.

Low dose rotenone treatment causes selective transcriptional activation of cell death related pathways in dopaminergic neurons in vivo

Mitochondrial complex I inhibition has been implicated in the degeneration of midbrain dopaminergic (DA) neurons in Parkinson's disease. However, the mechanisms and pathways that determine the cellular fate of DA neurons downstream of the mitochondrial dysfunction have not been fully identified. We conducted cell-type specific gene array experiments with nigral DA neurons from rats treated with the complex I inhibitor, rotenone, at a dose that does not induce cell death. The genome wide screen identified transcriptional changes in multiple cell death related pathways that are indicative of a simultaneous activation of both degenerative and protective mechanisms. Quantitative PCR analyses of a subset of these genes in different neuronal populations of the basal ganglia revealed that some of the changes are specific for DA neurons, suggesting that these neurons are highly sensitive to rotenone. Our data provide insight into potentially defensive strategies of DA neurons against disease relevant insults.

GPR54 and kisspeptins

The G-protein coupled receptor GPR54 has an essential role in the initiation and maintenance of mammalian fertility. Humans and mice with mutations in GPR54 have hypogonadotropic hypogonadism characterized by absence of sexual maturation and low levels of gonadotropic hormones (LH and FSH). The ligand for GPR54 is encoded by the KISS1 gene, which produces a 54-amino-acid peptide (metastin or kisspeptin-54) that can be cleaved into shorter peptides (kisspeptins 14, 13 and 10) with similar potencies. Kisspeptin administration stimulates gonadotropin release in several species by inducing GnRH secretion from hypothalamic GnRH neurons expressing GPR54. Kisspeptins are produced by neurons located in the AVPV and ARC regions of the hypothalamus. Expression of Kiss1 in these neurons is differentially regulated by sex steroids providing a mechanism by which testosterone or estrogen can regulate GnRH release. The AVPV region is sexually dimorphic with highest expression of kisspeptin in females. Positive feedback by estrogen on expression of Kiss1 in the AVPV region may be responsible for the pre-ovulatory LH surge during the estrus cycle. Central administration of kisspeptin to immature female rats can induce precocious activation of the gonadotropic axis, causing advanced vaginal opening, elevated uterus weight, increased serum levels of LH and estrogen and induce ovulation. Kisspeptins/GPR54 have also been implicated in regulating the estrus cycle of seasonal breeders and in the control of lactational amenorrhea. Expression of Gpr54 and Kiss1 have also been reported in several peripheral tissues including the pituitary, ovary, testes and the placenta raising the possibility that these genes may have additional functions in these tissues. Regulation of kisspeptin expression by peripheral factors such as leptin may be involved in coordinating metabolic status with the reproductive axis.

Analysis of selected genes in neuroendocrine tumours: insulinomas and phaeochromocytomas

Insulinomas and phaeochromocytomas are neuroendocrine tumours that may be either sporadic or manifestation of a familial cancer syndromes and are both derived from the neural crest. In the present study, gene components of different signalling pathways were investigated in sporadic human insulinomas and phaeochromocytomas to identify the responsible candidates. Ret and k-ras were tested for activating point mutations, and NF1, p53, BRCA1, nm23-H1, SDHB and SDHD for loss of heterozygosity (LOH). Twenty-two sporadic insulinomas and 15 phaeochromocytomas were analysed by the polymerase chain reaction using restriction fragment length polymorphism or dinucleotide repeat polymorphism methods. The results of our analysis demonstrate that the most frequent changes were point mutations of k-ras: 23% of insulinomas and 62% of phaeochromocytomas harboured k-ras mutations. The analysis also showed two phaeochromocytomas with point mutations of the ret oncogene. Only one insulinoma showed LOH of NF1, and another showed LOH of p53. Allelic loss of BRCA1 was detected in two insulinomas, and of nm23-H1 in another insulinoma. Allelic losses of the SDHB gene were present in two phaeochromocytoma and one insulinoma cases and allelic losses of SDHD were present in one phaeochromocytoma case. The changes observed in phaeochromocytomas were more homogenous and confined to k-ras and ret oncogenes, whereas insulinomas showed more heterogenic situation. Our findings may contribute to a better understanding of the genetic profile of neuroendocrine tumours.

The kisspeptin (KiSS-1)/GPR54 system in cancer biology

Kisspeptin (KiSS-1) gene, initially described as a melanoma metastasis suppressor gene, encodes a number of peptides (kp-54, kp-14, kp-13, kp-10), which are endogenous ligands to a G protein-coupled receptor, referred as hOT7T175 or AXOR12 or GPR54. So far intensive investigation has provided substantiate evidence supporting the role of KiSS-1/GPR54 system in cancer biology as well as in the regulation of the reproductive function and trophoblast invasion. The precise mechanism by which KiSS-1/GPR54 system is affecting cancer cell growth and metastasis includes complex endocrine, paracrine and autocrine actions. Nevertheless, the detail mechanism of such actions is still under intensive investigation. Herein we review the evidence which support the role of KiSS-1/GPR54 system in cancer biology.

Kisspeptin and KISS1R: a critical pathway in the reproductive system

In 2003, three groups around the world simultaneously discovered that KISS1R (GPR54) is a key gatekeeper of sexual maturation in both mice and men. Developmental changes in the expression of the ligand for KISS1R, kisspeptin, support its critical role in the pubertal transition. In addition, kisspeptin, a powerful stimulus of GNRH-induced gonadotropin secretion and may modulate both positive and negative sex steroid feedback effects at the hypothalamic level. Genetic studies in humans have revealed both loss-of-function and gainof-function mutations in patients with idiopathic hypogonadotropic hypogonadism and precocious puberty respectively. This review examines the kisspeptin/KISS1R pathway in the reproductive system.

Metastasis-associated gene expression profile of liver and subcutaneous lesions derived from mouse pheochromocytoma cells

The development of metastatic cancer is associated with overexpression or downregulation of specific genes and cell regulatory pathways. Some of these genes and pathways may be involved in invasion and dissemination of tumor cells, while others may promote seeding, survival or growth of cells at specific distant sites. In this investigation, gene expression profiles of nonmetastasizing tumors generated by injecting mouse pheochromocytoma cells (MPCs) subcutaneously were compared to those of liver tumors generated by injecting the cells intravenously. Both were compared to the cultured parental cell line. Tumors in the liver have a route of spread, anatomical distribution, and growth environment similar to naturally metastasizing pheochromocytomas, while intravenous injection of cells bypasses the initial steps of metastasis occurring spontaneously from a primary tumor. Eight genes were upregulated in liver tumors, 15 in subcutaneous tumors and seven in both compared to the cultured cells. Using quantitative real-time PCR, expression of five genes (Metap2, Reck, S100a4, Timp2, and Timp3) was verified as significantly lower in liver tumors than in subcutaneous tumors. Downregulation of these genes has been previously been associated with malignancy of pheochromocytomas. These findings indicate that different microenvironments can differentially affect the expression of metastasis-related genes in pheochromocytomas, and that overexpression or underexpression of these genes need not be present when the tumor cells are initially disseminated. The hepatic localization of tumors formed by intravenously injected MPC cells and the tumors' gene expression profile resembling that of naturally occurring pheochromocytoma metastases support the use of this model to study pheochromocytoma metastasis.