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Rab GTPases regulate the membrane transport pathways by recruiting their specific effector proteins. Melanophilin, a putative Rab effector, has recently been identified as a gene that is mutated in leaden mice, in which peripheral localization of melanosomes is impaired in melanocytes. Genetic studies suggest that three coat-color mutation genes, dilute (MyoVad), ashen (Rab27aash), and leaden (Mlphln), act in the same or overlapping pathways. Here we have cloned and characterized a human melanophilin homolog, which belongs to the rabphilin3/granuphilin-like Rab effector family. Cosedimentation assays using recombinant proteins reveal that melanophilin directly binds to Rab27a and myosin Va through its N-terminal and its first C-terminal coiled-coil region, respectively. Moreover, we show that Rab27a, melanophilin, and myosin Va form a ternary complex in the human melanocyte cell line HMV-II. These findings suggest that melanophilin has a role in bridging Rab27a on melanosomes and myosin Va on actin filaments during melanosome transport. We also propose that the Rab-binding region conserved in a novel rabphilin3/granuphilin-like Rab effector family constitutes an α-helix-based coiled-coil structure. [Copyright &y& Elsevier]

Presents a study that examined whether pit precursor cells express gastrin/cholecystokinin-B receptors (CCKB-R) in the gastric mucosa using hypergastrinemic transgenic mice and a mouse pit precursor cell line, GSM06. Characterization of the hypertrophied gastric mucosa in hypergastrinemic transgenic mice; Detection of CCKB-R messenger RNA in GSM06 cell lines; Analysis of the growth stimulatory effect of gastrin on GSM06 cells.

The receptor-type protein tyrosine kinases in murine pancreatic islets were screened to identify possible growth/differentiation factors in pancreatic beta-cells. The analysis revealed that insulin receptor-related receptor (IRR) is highly expressed in the islets as well as in several highly differentiated beta-cell lines derived from transgenic mice. Islets predominantly contain IRR as uncleaved proreceptors compared with IRR as processed forms in the beta-cell lines, suggesting that the activity of IRR is regulated on the level of processing proteases in vivo. To examine the IRR signaling pathway, a chimeric receptor consisting of the extracellular domain of insulin receptor and the intracellular domain of IRR was expressed in Chinese hamster ovary cells. The hybrid receptor is functional because insulin is capable of tyrosine-phosphorylating the catalytic domain in these cells. It also stimulates the tyrosine phosphorylation of insulin receptor substrate (IRS)-1 and IRS-2, indicating that both proteins serve as substrates of IRR-protein tyrosine kinase in intact cells. The phenotype of the IRS-2 knockout mouse recently reported suggests that an IRS-2-mediated signaling pathway controls the compensatory increase in pancreatic beta-cell mass in insulin-resistant states. From our findings of the specific expression of IRR and its ability of signaling to IRS-2, we speculate that this receptor might play a role in the regulation of beta-cell mass. [ABSTRACT FROM AUTHOR]

The molecular pathogenesis of diabetes remains poorly understood because of the genetic complexity of the disease. One possibly effective approach to elucidate the pathogenesis is to study an animal model with a similar phenotype. The TSOD (Tsumura, Suzuki, Obese Diabetes) mouse, a newly developed animal model, exhibits both diabetes and obesity with marked hyperinsulinemia and hypertrophy of the pancreatic islets and might represent a common form of obese type 2 diabetes in humans. Phenotypic characterization revealed that the TSOD mouse had both insulin resistance and impaired glucose-stimulated insulin secretion. A comprehensive genetic dissection of diabetes and obesity has been performed using F1 and F2 progeny between the TSOD and control BALB/cA strains. A genome-wide screen for loci linked to glucose homeostasis and body weight allowed us to map three quantitative trait loci (QTLs) involved in this disorder. The major genetic determinant of blood glucose levels was identified on chromosome 11. Furthermore, two independent QTLs involved in controlling body weight were found on chromosomes 1 and 2. The QTL on chromosome 2 also affected insulin levels significantly. Each QTL has distinct effects on different traits and a different mode of inheritance. Our study indicates that hyperglycemia and obesity are clearly controlled by distinct combinations of genetic loci in this mouse model and provides insights into the genetic basis of common forms of human type 2 diabetes with obesity. [ABSTRACT FROM AUTHOR]

The receptor protein tyrosine phosphatase phogrin primarily localizes to hormone secretory granules in neuroendocrine cells. Concurrent with glucose-stimulated insulin secretion, phogrin translocates to pancreatic β-cell plasma membranes, where it interacts with insulin receptors (IRs) to stabilize insulin receptor substrate 2 (IRS2) that, in turn, contributes to glucose-responsive β-cell growth. Pancreatic β-cell development was not altered in β-cell-specific, phogrin-deficient mice, but the thymidine incorporation rate decreased in phogrin-deficient islets with a moderate reduction in IRS2 protein expression. In this study, we analyzed the β-cell response to high-fat diet stress and found that the compensatory expansion in β-cell mass was significantly suppressed in phogrin-deficient mice. Phogrin-IR interactions occurred only in high-fat diet murine islets and proliferating β-cell lines, whereas they were inhibited by the intercellular binding of surface phogrin under confluent cell culture conditions. Thus, phogrin could regulate glucose-stimulated compensatory β-cell growth by changing its binding partner from another β-cell phogrin to IR in the same β-cells.

The enzyme-labeled antigen method is an immunohistochemical technique detecting plasma cells producing specific antibodies in tissue sections. The probe is an antigen labeled with an enzyme or biotin. This immunohistochemical technique is appliable to frozen sections of paraformaldehyde (PFA)-fixed tissues, but it has been difficult to apply it to formalin-fixed, paraffin-embedded (FFPE) sections. In the current study, factors inactivating the antibody reactivity during the process of preparing FFPE sections were investigated. Lymph nodes of rats immunized with horseradish peroxidase (HRP) or a mixture of keyhole limpet hemocyanin/ovalbumin/bovine serum albumin were employed as experimental models. Plasma cells producing specific antibodies, visualized with HRP (as an antigen with enzymatic activity) or biotinylated proteins in 4% PFA-fixed frozen sections, significantly decreased in unbuffered 10% formalin-fixed frozen sections. The positive cells were further decreased by paraffin embedding following formalin fixation. In paraffin-embedded sections fixed in precipitating fixatives such as ethanol and acetone and those prepared with the AMeX method, the antigen-binding reactivity of antibodies was preserved. Fixation in periodate-lysine-paraformaldehyde and Zamboni solution also kept the antigen-binding reactivity in paraffin to some extent. In conclusion, formalin fixation and paraffin embedding were major causes inactivating antibodies. Precipitating fixatives could retain the antigen-binding reactivity of antibodies in paraffin-embedded sections., Competing Interests: VThe authors have no conflict of interest to disclose., (2022 The Japan Society of Histochemistry and Cytochemistry.)

Ceramide synthase 6 (CERS6) promotes lung cancer metastasis by stimulating cancer cell migration. To examine the underlying mechanisms, we performed luciferase analysis of the CERS6 promoter region and identified the Y-box as a cis-acting element. As a parallel analysis of database records for 149 non-small-cell lung cancer (NSCLC) cancer patients, we screened for trans-acting factors with an expression level showing a correlation with CERS6 expression. Among the candidates noted, silencing of either CCAAT enhancer-binding protein γ (CEBPγ) or Y-box binding protein 1 (YBX1) reduced the CERS6 expression level. Following knockdown, CEBPγ and YBX1 were found to be independently associated with reductions in ceramide-dependent lamellipodia formation as well as migration activity, while only CEBPγ may have induced CERS6 expression through specific binding to the Y-box. The mRNA expression levels of CERS6, CEBPγ, and YBX1 were positively correlated with adenocarcinoma invasiveness. YBX1 expression was observed in all 20 examined clinical lung cancer specimens, while 6 of those showed a staining pattern similar to that of CERS6. The present findings suggest promotion of lung cancer migration by possible involvement of the transcription factors CEBPγ and YBX1., (© 2021 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

Cell division cycle 7 (CDC7), a serine/threonine kinase, plays important roles in DNA replication. We developed a highly specific CDC7 inhibitor, TAK-931, as a clinical cancer therapeutic agent. This study aimed to identify the potential combination partners of TAK-931 for guiding its clinical development strategies. Unbiased high-throughput chemical screening revealed that the highest synergistic antiproliferative effects observed were the combinations of DNA-damaging agents with TAK-931. Functional phosphoproteomic analysis demonstrated that TAK-931 suppressed homologous recombination repair activity, delayed recovery from double-strand breaks, and led to accumulation of DNA damages in the combination. Whole-genome small interfering RNA library screening identified sensitivity-modulating molecules, which propose the experimentally predicted target cancer types for the combination, including pancreatic, esophageal, ovarian, and breast cancers. The efficacy of combination therapy in these cancer types was preclinically confirmed in the corresponding primary-derived xenograft models. Thus, our findings would be helpful to guide the future clinical strategies for TAK-931., (Copyright © 2021 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

Sphingolipids constitute a class of bio-reactive molecules that transmit signals and exhibit a variety of physical properties in various cell types, though their functions in cancer pathogenesis have yet to be elucidated. Analyses of gene expression profiles of clinical specimens and a panel of cell lines revealed that the ceramide synthase gene CERS6 was overexpressed in non-small-cell lung cancer (NSCLC) tissues, while elevated expression was shown to be associated with poor prognosis and lymph node metastasis. NSCLC profile and in vitro luciferase analysis results suggested that CERS6 overexpression is promoted, at least in part, by reduced miR-101 expression. Under a reduced CERS6 expression condition, the ceramide profile became altered, which was determined to be associated with decreased cell migration and invasion activities in vitro. Furthermore, CERS6 knockdown suppressed RAC1-positive lamellipodia/ruffling formation and attenuated lung metastasis efficiency in mice, while forced expression of CERS6 resulted in an opposite phenotype in examined cell lines. Based on these findings, we consider that ceramide synthesis by CERS6 has important roles in lung cancer migration and metastasis., (© 2020 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

Resveratrol (RSV) has recently attracted keen interest because of its pleiotropic effects. It exerts a wide range of health-promoting effects. In addition to health-promoting effects, RSV possesses anti-carcinogenic activity. However, a non-physiological concentration is needed to achieve an anti-cancer effect, and its in vivo bioavailability is low. Therefore, the clinical application of phytochemicals requires alternative candidates that induce the desired effects at a lower concentration and with increased bioavailability. We previously reported a low IC 50 of vaticanol C (VTC), an RSV tetramer, among 12 RSV derivatives (Ito T. et al, 2003). However, the precise mechanism involved remains to be determined. Here, we screened an in-house chemical library bearing RSV building blocks ranging from dimers to octamers for cytotoxic effects in several leukemia and cancer cell lines and their anti-cancer drug-resistant sublines. Among the compounds, VTC exhibited the highest cytotoxicity, which was partially inhibited by a caspase 3 inhibitor, Z-VAD-FMK. VTC decreased the expression of sphingosine kinase 1, sphingosine kinase 2 and glucosylceramide synthase by transcriptional or post-transcriptional mechanisms, and increased cellular ceramides/dihydroceramides and decreased sphingosine 1-phosphate (S1P). VTC-induced sphingolipid rheostat modulation (the ratio of ceramide/S1P) is thought to be involved in cellular apoptosis. Indeed, exogenous S1P addition modulated VTC cytotoxicity significantly. A combination of SPHK1, SPHK2, and GCS chemical inhibitors induced sphingolipid rheostat modulation, cell growth suppression, and cytotoxicity similar to that of VTC. These results suggest the involvement of sphingolipid metabolism in VTC-induced cytotoxicity, and indicate VTC is a promising prototype for translational research., Competing Interests: All authors disclose no actual or potential conflict of interest including any financial, personal or other relationships with other people or organization.

Replication stress (RS) is a cancer hallmark; chemotherapeutic drugs targeting RS are widely used as treatments for various cancers. To develop next-generation RS-inducing anticancer drugs, cell division cycle 7 (CDC7) has recently attracted attention as a target. We have developed an oral CDC7-selective inhibitor, TAK-931, as a candidate clinical anticancer drug. TAK-931 induced S phase delay and RS. TAK-931-induced RS caused mitotic aberrations through centrosome dysregulation and chromosome missegregation, resulting in irreversible antiproliferative effects in cancer cells. TAK-931 exhibited significant antiproliferative activity in preclinical animal models. Furthermore, in indication-seeking studies using large-scale cell panel data, TAK-931 exhibited higher antiproliferative activities in RAS -mutant versus RAS -wild-type cells; this finding was confirmed in pancreatic patient-derived xenografts. Comparison analysis of cell panel data also demonstrated a unique efficacy spectrum for TAK-931 compared with currently used chemotherapeutic drugs. Our findings help to elucidate the molecular mechanisms for TAK-931 and identify potential target indications.

Autocrine insulin signaling is critical for pancreatic β-cell growth and activity and is at least partially controlled by protein-tyrosine phosphatases (PTPs) that act on insulin receptors (IRs). The receptor-type PTP phogrin primarily localizes on insulin secretory granules in pancreatic β cells. We recently reported that phogrin knockdown decreases the protein levels of insulin receptor substrate 2 (IRS2), whereas high-glucose stimulation promotes formation of a phogrin-IR complex that stabilizes IRS2. However, the underlying molecular mechanisms by which phogrin affects IRS2 levels are unclear. Here, we found that relative to wildtype mice, IRS2 levels in phogrin-knockout mice islets decreased by 44%. When phogrin was silenced by shRNA in pancreatic β-cell lines, glucose-induced insulin signaling led to proteasomal degradation of IRS2 via a negative feedback mechanism. Phogrin overexpression in a murine hepatocyte cell line consistently prevented chronic insulin treatment-induced IRS2 degradation. In vitro , phogrin directly bound the IR without the assistance of other proteins and protected recombinant PTP1B from oxidation to potentiate its activity toward the IR. Furthermore, phogrin expression suppressed insulin-induced local generation of hydrogen peroxide and subsequent PTP1B oxidation, which allowed progression of IR dephosphorylation. Together, these results suggest that a transient interaction of phogrin with the IR enables glucose-stimulated autocrine insulin signaling through the regulation of PTP1B activity, which is essential for suppressing feedback-mediated IRS2 degradation in pancreatic β cells., (© 2018 by The American Society for Biochemistry and Molecular Biology, Inc.)

In cancer cells the small compounds erastin and RSL3 promote a novel type of cell death called ferroptosis, which requires iron-dependent accumulation of lipid reactive oxygen species. Here we assessed the contribution of lipid peroxidation activity of lipoxygenases (LOX) to ferroptosis in oncogenic Ras-expressing cancer cells. Several 12/15-LOX inhibitors prevented cell death induced by erastin and RSL3. Furthermore, siRNA-mediated silencing of ALOX15 significantly decreased both erastin-induced and RSL3-induced ferroptotic cell death, whereas exogenous overexpression of ALOX15 enhanced the effect of these compounds. Immunofluorescence analyses revealed that the ALOX15 protein consistently localizes to cell membrane during the course of ferroptosis. Importantly, treatments of cells with ALOX15-activating compounds accelerated cell death at low, but not high doses of erastin and RSL3. These observations suggest that tumor ferroptosis is promoted by LOX-catalyzed lipid hydroperoxide generation in cellular membranes., (© 2017 The Authors. Cancer Science published by John Wiley & Sons Australia, Ltd on behalf of Japanese Cancer Association.)

1. Following oral administration of [ 14 C]TAK-438, the radioactivity was rapidly absorbed in rats and dogs. The apparent absorption of the radioactivity was high in both species. 2. After oral administration of [ 14 C]TAK-438 to rats, the radioactivity in most tissues reached the maximum at 1-hour post-dose. By 168-hour post-dose, the concentrations of the radioactivity were at very low levels in nearly all the tissues. In addition, TAK-438F was the major component in the stomach, whereas TAK-438F was the minor component in the plasma and other tissues. High accumulation of TAK-438F in the stomach was observed after oral and intravenous administration. 3. TAK-438F was a minor component in the plasma and excreta in both species. Its oxidative metabolite (M-I) and the glucuronide of a secondary metabolite formed by non-oxidative metabolism of M-I (M-II-G) were the major components in the rat and dog plasma, respectively. The glucuronide of M-I (M-I-G) and M-II-G were the major components in the rat bile and dog urine, respectively, and most components in feces were other unidentified metabolites. 4. The administered radioactive dose was almost completely recovered. The major route of excretion of the drug-derived radioactivity was via the feces in rats and urine in dogs.

Small luminescent molecular probes based on the iridium(III) complex BTP, (btp)2Ir(acac) (btp = benzothienylpyridine, acac = acetylacetone) have been developed for sensing intracellular and in vivo O2. These compounds are BTPSA (containing an anionic carboxyl group), BTPNH2 (containing a cationic amino group), and BTPDM1 (containing a cationic dimethylamino group); all substituents are incorporated into the ancillary acetylacetonato ligand of BTP. Introduction of the cationic dimethylamino group resulted in an almost 20-fold increase in cellular uptake efficiency of BTPDM1 by HeLa cells compared with BTP. The phosphorescence intensity of BTPDM1 internalized in living cells provided a visual representation of the O2 gradient produced by placing a coverslip over cultured monolayer cells. The intracellular O2 levels (pO2) inside and outside the edge of the coverslip could be evaluated by measuring the phosphorescence lifetime of BTPDM1. Furthermore, intravenous administration of 25 nmol BTPDM1 to tumor-bearing mice allowed the tumor region to be visualized by BTPDM1 phosphorescence. The lifetime of BTPDM1 phosphorescence from tumor regions was much longer than that from extratumor regions, thereby demonstrating tumor hypoxia (pO2 = 6.1 mmHg for tumor and 50 mmHg for extratumor epidermal tissue). Tissue distribution studies showed that 2 h after injection of BTPDM1 into a mouse, the highest distribution was in liver and kidney, while after 24 h, BTPDM1 was excreted in the feces. These results demonstrate that BTPDM1 can be used as a small molecular probe for measuring intracellular O2 levels in both cultured cells and specific tissues and organs.

Previous studies on the metabolic fate of resatorvid (TAK-242) have shown that species differences in the pharmacokinetics of 4-amino-3-chlorophenyl hydrogen sulfate (M-III), a metabolite of TAK-242, between rats and dogs are mainly attributable to the urinary excretion process. In the present study, the renal uptake mechanism of M-III was investigated using kidney slices and Xenopus laevis oocytes expressing rat organic anion transporter 1 (rOat1; Slc22a6) and rOat3 (Slc22a8). The uptake of p-aminohippuric acid (PAH), a substrate for Oats, by kidney slices from rats and dogs increased at 37 °C and M-III inhibited the uptake. The initial uptake clearance of M-III by rat kidney slices was 0.295 and 0.0114 ml/min/g at 37 °C and 4 °C, respectively. The Eadie-Hofstee plot of M-III uptake at 37 °C revealed two-component transport processes with K(m) values being 6.48 and 724 µmol/l. The uptake was inhibited by probenecid (PBC), PAH and benzylpenicillin (PCG). In contrast, in dog kidney slices, the initial uptake clearance of M-III was 8.70 × 10(-3) and 9.00 × 10(-3) ml/min/g at 37 °C and 4 °C, respectively, and the uptake was not inhibited by PBC. Furthermore, rOat1- and rOat3-expressing oocytes mediated M-III uptake and the uptake was inhibited by PAH and PCG, respectively. These results suggest that rOat1 and rOat3 are responsible for the renal uptake of M-III in rats. Moreover, it is speculated that Oat(s) is unable to transport M-III in dogs and that the difference in the substrate recognition of Oat(s) contributes to the species difference in the pharmacokinetics of M-III between rats and dogs., (Copyright © 2013 John Wiley & Sons, Ltd.)

We recently reported that TAK-593, a novel imidazo[1,2-b]pyridazine derivative, is a highly potent and selective inhibitor of the vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF) receptor tyrosine kinase families. Moreover, TAK-593 exhibits a uniquely long-acting inhibitory profile towards VEGF receptor 2 (VEGFR2) and PDGF receptor β (PDGFRβ). In this study, we demonstrated that TAK-593 potently inhibits VEGF- and PDGF-stimulated cellular phosphorylation and proliferation of human umbilical vein endothelial cells and human coronary artery smooth muscle cells. TAK-593 also potently inhibits VEGF-induced tube formation of endothelial cells co-cultured with fibroblasts. Oral administration of TAK-593 exhibited strong anti-tumor effects against various human cancer xenografts along with good tolerability despite a low level of plasma exposure. Even after the blood and tissue concentrations of TAK-593 decreased below the detectable limit, a pharmacodynamic marker (phospho VEGFR2) was almost completely suppressed, indicating that its long duration of enzyme inhibition might contribute to the potent activity of TAK-593. Immunohistochemical staining indicated that TAK-593 showed anti-proliferative and pro-apoptotic effects on tumors along with a decrease of vessel density and inhibition of pericyte recruitment to microvessels in vivo. Furthermore, dynamic contrast-enhanced magnetic resonance imaging revealed that TAK-593 reduced tumor vessel permeability prior to the onset of anti-tumor activity. In conclusion, TAK-593 is an extremely potent VEGFR/PDGFR kinase inhibitor whose potent anti-angiogenic activity suggests therapeutic potential for the treatment of solid tumors., (© 2013 Japanese Cancer Association.)

We previously identified PSMD2, a subunit of the 19S regulatory complex of proteasomes, as a constituent of a signature associated with the acquisition of metastatic phenotype and poor prognosis in lung cancers. In the present study, we found that knockdown of PSMD2 decreased proteasome activity, and induced growth inhibition and apoptosis in lung cancer cell lines. These effects of siRNA-mediated PSMD2 inhibition were associated with changes in the balance between phosphorylated AKT and p38, as well as with induction of p21. In addition, patients with higher PSMD2 expression had poorer prognosis and a small fraction of lung cancer specimens carried increased copies of PSMD2. Notably, our findings clearly illustrate that lung adenocarcinomas can be divided into two groups; those with and without general upregulation of proteasome pathway genes including PSMD2. This general upregulation was significantly more prevalent in the non-terminal respiratory unit (non-TRU)-type, a recently proposed genetically and clinicopathologically relevant expression profile-defined classification of adenocarcinomas (P < 0.001 by Fisher's exact test). Patients with adenocarcinomas with general upregulation had significantly shorter survival after potentially curative resection (P = 0.0001 by log-rank test) independent of disease stage, as shown by multivariate Cox regression analysis. Our results suggest that PSMD2 may be a good molecular target candidate and that other co-regulated proteasome pathway genes and/or their common regulator(s) might also be potential targets, warranting future study including elucidation of the underlying common regulatory mechanism., (Copyright © 2011 Wiley-Liss, Inc.)

Phogrin, a receptor tyrosine phosphatase-like protein, is localized to dense-core secretory granules (SGs) in various neuroendocrine cells. A previous report showed that the N-terminal luminal domain mediates targeting of this protein to SGs in AtT-20 cells. Here, we show that the luminal domain specifically interacts with carboxypeptidase E (CPE), one of the key proteins involved in peptide hormone sorting, in a weakly acidic condition. The luminal domain consists of pro-sequence domain (pro) and subsequent N-side mature domain and the pro domain was preferentially required for phogrin interaction with CPE and for its targeting to SGs. Small interfering RNA-directed reduction of the CPE protein level resulted in an improper accumulation of phogrin at the trans-Golgi network in AtT-20 cells. This finding indicates that CPE is involved in the sorting process of phogrin to SGs. However, SG localization of CPE was hindered by overexpression of the phogrin mutants that lack the transport motif of binding to clathrin adaptor complexes. Phogrin-depleted AtT-20 cells also exhibited reduced CPE targeting and increased CPE degradation. Our results suggest that the luminal interaction between phogrin and CPE contributes to their targeting to SGs in a cooperative manner in neuroendocrine cells., (© 2011 John Wiley & Sons A/S.)

The pharmacokinetics of TAK-242 (ethyl (6R)-6- [N-(2-chloro-4-fluorophenyl)sulfamoyl]cyclohex-1-ene-1-carboxylate, CAS 243984-11-4) and its metabolites were investigated in rats and dogs after intravenous (i.v.) dosing of TAK-242 using two types of radiolabeled TAK-242: [phenyl ring-U-14C]TAK-242 and [cyclohexene ring-U-14C]TAK-242. The phenyl ring moiety of TAK-242 yielded 2-chloro-4-fluoroaniline, M-I, and M-I was further acetylated and conjugated to form M-II and the glucuronide (M-I-G), respectively. M-I was also converted to M-III and M-IV by hydroxylation and subsequent sulfate conjugation. Meanwhile, the cyclohexene ring moiety of TAK-242 was metabolized to glutathione conjugate, M-SG, followed by further metabolism of M-SG to form cysteine conjugate (M-Cys) and mercapturic acid conjugate (M-Mer). After i.v. injection of [phenyl ring-U-14C]TAK-242 to rats and dogs, the 14C concentrations in dogs declined slowly with a half-life of about 1 week although that in rats was about 6 h. The predominant components in the plasma of rats and dogs were M-I-G and M-III, respectively. After i.v. injection of [cyclohexene ring-U-14C]TAK-242 to rats and dogs, 14C-components unextractable by organic solvents were observed in the plasma. These results indicated two unique metabolic fates of TAK-242. The phenyl ring moiety of TAK-242 showed species differences between rats and dogs in the metabolism and excretion kinetics and the cyclohexene ring moiety of TAK-242 showed potential for covalent binding to endogenous components such as plasma proteins.

Cholesterol is reportedly abundant in the endocrine secretory granule (SG) membrane. In this study, we examined the involvement of cholesterol biosynthesis intermediates and inhibitors in insulin secretion and SG formation mechanisms. There are two routes for the supply of cholesterol to the cells: one via de novo biosynthesis and the other via low-density lipoprotein receptor-mediated endocytosis. We found that insulin secretion and content are diminished by β-hydroxy-β-methylglutaryl-coenzyme A inhibitor lovastatin but not by lipoprotein depletion from the culture medium in MIN6 β-cells. Cholesterol biosynthesis intermediates mevalonate, squalene, and geranylgeranyl pyrophosphate enhanced glucose-stimulated insulin secretion, and the former two increased insulin content. The glucose-stimulated insulin secretion-enhancing effect of geranylgeranyl pyrophosphate was also confirmed in perifusion with rat islets. Morphologically, mevalonate and squalene increased the population of SGs without affecting their size. In contrast, lovastatin increased the SG size with reduction of insulin-accumulating dense cores, leading to a decrease in insulin content. Furthermore, insulin was secreted in a constitutive manner, indicating disruption of regulated insulin secretion. Because secretogranin III, a cholesterol-binding SG-residential granin-family protein, coincides with SG localization based on the cholesterol composition, secretogranin III may be associated with insulin-accumulating mechanisms. Although the SG membrane exhibits a high cholesterol composition, we could not find detergent-resistant membrane regions using a lipid raft-residential protein flotillin and a fluorescent cholesterol-Si-pyrene probe as markers on a sucrose-density gradient fractionation. We suggest that the high cholesterol composition of SG membrane with 40-50 mol% is crucial for insulin secretion and SG formation functions.

Background: 5-fluorouracil-(5-FU)-based adjuvant chemotherapy is widely used for the treatment of colorectal cancer. However, 5-FU resistance in the course of treatment has become more common. Therefore, new therapeutic strategies and/or new adjuvant drugs still need to be explored., Methods: Two colon-cancer-derived cell lines, colon26 and HT29, were used to investigate the effect of 5-FU, 3-methyladenine (3-MA, an autophagy inhibitor), or their combination on apoptotic cell death and autophagy. MTT assay, Hochest plus propidium iodide (PI) staining, and DNA fragmentation assay were used to observe apoptosis. Meanwhile, monodansylcadaverine (MDC) was used to detect autophagy. Finally, immunoblotting assay was used to explore the molecular change that occurred., Results: We observed the apoptosis induced by 5-FU in colon cancer cells. Meanwhile, autophagy was also stimulated. The combination treatment of 3-MA and 5-FU significantly increased the apoptotic cell death. By isolating the subcellular fractions of mitochondria and cytosol, we observed that the release of cytochrome c was increased in combination-treated cells. Cytochrome c resulted in the activation of caspase-3, thus activating PARP. Moreover, the anti-apoptotic protein, Bcl-xL, was significantly downregulated by 3-MA., Conclusions: Our results suggest that 5-FU-induced apoptosis in colon cancer cells can be enhanced by the inhibitor of autophagy, 3-MA. Autophagy might play a role as a self-defense mechanism in 5-FU-treated colon cancer cells, and its inhibition could be a promising strategy for the adjuvant chemotherapy of colon cancer.

The role of P-glycoprotein (P-gp, ABCB1) on the absorption process was investigated by drug-drug interaction studies of TAK-427 with P-gp inhibitors (erythromycin, ketoconazole or quinidine) in rats and by transport studies using rat multidrug resistance (MDR1) stably expressing cells and rat small intestine mounted in a Ussing-type chamber. TAK-427 showed high efflux activity with low permeability in rat MDR1a and MDR1b stably expressing cells and was revealed to be a typical substrate for P-gps. Although TAK-427 was mainly absorbed from the small intestine in rats, a large part of the dosed compound remained in the gastrointestinal tract. Orally co-administered P-gp inhibitors (50 mg/kg) increased the AUC of TAK-427 after a 5 mg/kg oral dose 5.4- to 18.3-fold, whereas orally administered P-gp inhibitors had a minor effect on the increase in the AUC of TAK-427 (1.3- to 2.2-fold) after a 0.5 mg/kg intravenous dose. Thus, the bioavailability of TAK-427 after oral administration in rats (7.3%) markedly increased when co-administered with P-gp inhibitors (28.6-57.6%). Moreover, the transport of TAK-427 was predominantly secretory throughout the rat small intestine and was inhibited by P-gp inhibitors. In conclusion, P-gp can markedly reduce the absorption of a typical P-gp substrate by its efflux activity throughout the absorption site.

Granin-family proteins, including chromogranin A and secretogranin III, are sorted to the secretory granules in neuroendocrine cells. We previously demonstrated that secretogranin III binds chromogranin A and targets it to the secretory granules in pituitary corticotrope-derived AtT-20 cells. However, secretogranin III has not been identified in adrenal chromaffin and PC12 cells, where chromogranin A is correctly sorted to the secretory granules. In this study, low levels of a large and noncleaved secretogranin III have been identified in PC12 cells and rat adrenal glands. Although the secretogranin III expression was limited in PC12 cells, when the FLAG-tagged secretogranin III lacking the secretory granule membrane-binding domain was expressed excessively, hemagglutinin-tagged chromogranin A was unable to target to the secretory granules at the tips and shifted to the constitutive secretory pathway. Secretogranin III was able to bind the aggregated form of chromogranin A, suggesting that a small quantity of secretogranin III is enough to carry a large quantity of chromogranin A. Furthermore, secretogranin III bound adrenomedullin, a major peptide hormone in chromaffin cells. Indeed, small interfering RNA-directed secretogranin III depletion impaired intracellular retention of chromogranin A and adrenomedullin, suggesting that they are constitutively released to the medium. We suggest that the sorting function of secretogranin III for chromogranin A is common in PC12 and chromaffin cells as well as in other endocrine cells, and a small amount of secretogranin III is able to sort chromogranin A aggregates together with adrenomedullin to secretory granules.

Pancreatic beta-cells are susceptible to reactive oxygen species (ROS), which are known to be generated by high or low glucose (LG), hypoxic, or cytokine-producing conditions. When we cultured mouse beta-cell-derived MIN6 cells in a LG condition, we detected a significant generation of ROS, including hydrogen peroxide, which was comparable to the ROS production in hypoxic or cytokine-treated conditions. ROS accumulation induced by the LG culture led to cell death, which was prevented by the ROS scavengers N-acetylcysteine and manganese(III)tetrakis(4-benzoic acid) porphyrin. We next investigated the mechanism of stress-activated protein kinases (SAPKs), c-jun N-terminal kinase (JNK) and p38, in ROS-induced MIN6 cell death. Activation of p38 occurred immediately after the LG culture, whereas JNK activation increased slowly 8 h later. Adenoviral p38 expression decreased MIN6 cell death, whereas the JNK expression increased it. Consistently, blocking p38 activation by inhibitors increased beta-cell death, whereas JNK inhibitors decreased it. We then examined the role of MAPK phosphatases (MKPs) specific for stress-activated protein kinases in beta-cell death. We found that MKP-1 presented an increase in its oxidized product after the LG culture. ROS scavengers prevented the appearance of this oxidized product and JNK activation. Thus, ROS-induced MKP inactivation causes sustained activation of JNK, which contributes to beta-cell death. Adenoviral overexpression of MKP-1 and MKP-7 prevented the phosphorylation of JNK at 36 h after the LG culture, and decreased MIN6 beta-cell death. We suggest that beta-cell death is regulated by interactions between JNK and its specific MKPs.

Proteins on the membrane of secretory granules (SGs) involved in their biogenesis and exocytosis are poorly characterized compared with those of synaptic vesicle in neurons. Thus the secretory granule membrane was prepared from a mouse pancreatic beta-cell line MIN6 by subcellular fractionation, and protein constituents were analyzed by microscale two-dimensional liquid chromatography coupled with electrospray ionization tandem mass spectrometry. Using this proteomics approach, one of the p24 family proteins, p23, was unexpectedly found in the granule fraction, although p24 proteins are generally regarded as functioning in the early secretory pathways between the endoplasmic reticulum and the Golgi apparatus. We further showed that p23 is expressed at high levels in endocrine cells. Furthermore, immunocytochemical analyses of pancreatic beta-cells at the light and electron microscopic levels demonstrated that a significant amount of p23 is localized on the insulin granule membrane, although it is most intensely concentrated at the cis-Golgi compartment as previously shown in non-endocrine cells. These findings suggest that a fraction of p23 enters post-Golgi compartments and may function in the biogenesis and/or quality control of SGs.

Purpose: Stable transformants expressing human multidrug resistance 1 (MDR1), monkey MDR1, canine MDR1, rat MDR1a, rat MDR1b, mouse mdr1a, and mouse mdr1b in LLC-PK1 were established to investigate species differences in P-glycoprotein (P-gp, ABCB1) mediated efflux activity., Methods: The seven cDNAs of MDR1 from five animals were cloned, and their transformants stably expressing the series of MDR1 in LLC-PK1 were established. Transport studies of clarithromycin, daunorubicin, digoxin, erythromycin, etoposide, paclitaxel, propranolol, quinidine, ritonavir, saquinavir, verapamil, and vinblastine were performed by using these cells, and efflux activity was compared among the species., Results: Except for propranolol, all compounds showed efflux activity in all transformants, and were judged to be substrates of P-gp. There were slight interspecies and interisoforms differences in the substrate recognition. However, the efflux ratio among the series of the MDR1 stably expressing cells showed good correlation as represented between human and monkey MDR1, and poor correlation as represented between human MDR1 and mouse mdr1a, and human and canine MDR1., Conclusions: Results in the present study indicate that all MDR1 stably expressing cells have efflux activity for various P-gp substrates, and that interspecies differences and similarities of the P-gp substrate efflux activity may exist.

Purpose: This study was conducted to gain insight into the relationship between expression profiles and underlying genetic changes, which are known to be important for the pathogenesis of lung cancers., Methods: Expression profiles of 18,175 unique genes and three major targets for genetic changes, p53, epidermal growth factor receptor (EGFR), and K-ras, were investigated in 149 patients with non-small-cell lung cancer, including 90 patients with adenocarcinoma to determine their relationships with various clinicopathologic features and Gene Ontology (GO) terms., Results: This study successfully established a basis for expression profile-defined classification, which can classify adenocarcinomas into two major types, terminal respiratory unit (TRU) type and non-TRU type. Our GO term-based identifier of particular biologic processes, molecular functions, and cellular compartments clearly showed characteristic retention of normal peripheral lung features in TRU type, in sharp contrast to the significant association of non-TRU type with cell cycling and proliferation-related features. While significantly higher frequency of EGFR mutation was observed in TRU type, we found that the presence of EGFR mutations was a significant predictor of shorter postoperative survival for TRU type, independent of disease stage. We were also able to identify a set of genes in vivo with significant upregulation in the presence of EGFR mutations., Conclusion: This study has shed light on heterogeneity in lung cancers, especially in adenocarcinomas, by establishing a molecularly, genetically, and clinically relevant, expression profile-defined classification. Future studies using independent patient cohorts are warranted to confirm the prognostic significance of EGFR mutations in TRU-type adenocarcinoma.

Nestin is a member of intermediate filaments abundantly expressed in neural stem cells and glioblastomas. The nestin gene has four exons and three introns, and neural cell-specific expression is regulated by the second intron. We previously reported that nestin was invariably detected in the tumor endothelium in gliomas even though tumor cells were negative for nestin. In the present study, we further confirmed nestin immunostaining in tumor endothelium of a variety of common cancers, including lung, stomach, colon, and cervical carcinomas. We examined an endothelium-specific regulator using human umbilical vein endothelial cells (HUVECs) and human glioblastoma-derived U251 cells. In a luciferase reporter assay, the first intron plus 5' upstream promoter (5'UP) gave the highest activity, followed by 5'UP, and the second intron plus 5'UP. However, the assay values were much lower by HUVEC extracts than by U251 cell extracts. Although green fluorescent protein expression was positive over all U251 cells under either the first intron, second intron, or ubiquitously active CAG promoter, the fluorescence in HUVECs was limited to a few cells even under the first intron. This difference came from the growth feature of HUVECs which exhibit growth arrest by contact inhibition. We found that the nestin expression was specific to proliferative endothelium, by using proliferation markers in hemangioblastomas and in situ hybridization. Using an endothelial tube formation assay, tyrosine kinase domain-deleted VEGF receptor KDR effectively abolished the tube formation under the first intron. We suggest that the nestin expression in tumor endothelium is enhanced by the first intron.

Injection of carbon tetrachloride (CCl4) intraperitoneally into model animals induces acute liver injury mediated by reactive oxygen species (ROS) as normal metabolites in hepatocytes. In this study, the molecular process in this type of liver injury was analyzed from the aspect of liver function and regulatory factors. Down-regulation of liver-specific genes was accomplished through suppression of liver-enriched transcription factors and box A factors found in the catalase gene, and induction of NF-kappaB, AP-1 and a novel factor denoted as 'cx' in the catalase gene. Expression profiles of these genes were restored to normal levels in the late stage of injury (48 h). On the other hand, hepatocyte growth factor (HGF) and proliferating cell nuclear antigen (PCNA) were induced in the early stage (6 h) and 36 h, respectively. Interestingly, ERK2 was transiently activated at 3 h CCl4-treatment. These observations suggested that hepatotoxin by CCl4-injection concomitantly induces both processes in acute injury and liver regeneration.

Secretory vesicle exocytosis is a highly regulated process involving vesicle targeting, priming, and membrane fusion. Rabs and SNAREs play a central role in executing these processes. We have shown recently that Rab27a and its effector, granuphilin, are involved in the exocytosis of insulin-containing secretory granules through a direct interaction with the plasma membrane syntaxin 1a in pancreatic beta cells. Here, we demonstrate that fluorescence-labeled insulin granules are peripherally accumulated in cells overexpressing granuphilin. The peripheral location of granules is well overlapped with both localizations of granuphilin and syntaxin 1a. The plasma membrane targeting of secretory granules is promoted by wild-type granuphilin but not by granuphilin mutants that are defective in binding to either Rab27a or syntaxin 1a. Granuphilin directly binds to the H3 domain of syntaxin 1a containing its SNARE motif. Moreover, introduction of the H3 domain into beta cells induces a dissociation of the native granuphilin-syntaxin complex and a marked reduction of newly docked granules. These results indicate that granuphilin plays a role in tethering insulin granules to the plasma membrane by an interaction with both Rab27a and syntaxin 1a. The complex formation of these three proteins may contribute to the specificity of the targeting process during the exocytosis of insulin granules.

Autocrine motility factor (AMF), which is identical to phosphohexose isomerase (PHI)/glucose-6-phosphate isomerase (GPI), a ubiquitous enzyme essential for glycolysis, neuroleukin (NLK), a neurotrophic growth factor, and maturation factor (MF) mediating the differentiation of human myeloid cells, enhances the motility and metastatic ability of tumor cells. AMF/PHI activity is elevated in the serum or urine in patients with malignant tumors. Here, we constructed an amf/phi/nlk/mf gene using adenovirus vector and transfected into two tumor cell lines. Overexpression of AMF/PHI/NLK/MF enhanced AMF secretion into the culture media in both tumor cell lines. However, upregulation of motility and metastatic ability was found only in metastatic fibrosarcoma cells expressing an AMF receptor, gp78, and was not found in gp78-undetectable osteosarcoma cells. Thus, not only serum AMF activity but also gp78-expression in tumor cells may be required for metastasis-related motility induction. With the use of microarray analyses, we detected two augmented genes, rho GDP dissociation inhibitor beta and kinesin motor 3A, as well as AMF itself. The RNA message and protein expression of these two molecules was confirmed to be upregulated, suggesting a possible association with AMF-induced signaling for cell motility and metastasis.

Nestin is one of the intermediate filament proteins and mainly expressed during the development of the central nervous system. We examined the cerebellum of patients with Creutzfeldt-Jakob disease (CJD), multiple system atrophy and amyotrophic lateral sclerosis, using anti-human nestin antibodies. The antibodies strongly immunostained the cytoplasm, dendrites and torpedoes of Purkinje cells in CJD. However, Purkinje cells in other neurodegenerative disorders were not nestin-immunoreactive. Nestin immunoreactivities became more marked as the pathological severity in the cerebellum increased. Our findings suggest that nestin is strongly expressed in Purkinje cells in pathologically advanced CJD and show the possibility that Purkinje cells are being reactivated to promote survival.

Purpose: The authors examined whether recombinant human endostatin (rhEndostatin), an antiangiogenic agent, is effective against a human neuroblastoma cell line (designated TNB9) using a human neuroblastoma xenograft model and investigated whether continuous infusion is more effective than intermittent administration., Methods: In the first experiment, when tumors on the back of nude mice reached a weight of 90 to 95 mg, rhEndostatin, 10 mg/kg/d mouse weight, was administered subcutaneously to the mice (n = 5) every day for 10 consecutive days. In the second experiment, the same daily dose of rhEndostatin was administered continuously to the TNB9-bearing mice (n = 6) via subcutaneous infusion pumps for 3 consecutive days with total dose being 30% of that in the first experiment. Nestin and factor VIII expression levels were studied immunohistochemically to elucidate whether histologic evidence of the effects of rhEndostatin was present on day 4 in the second experiment., Results: In the first experiment, relative tumor weight in treated mice (n = 5) was significantly less than that in controls (n = 12) on day 2 only after treatment initiation (P <.05). The maximum inhibition rate (MIR) of TNB9 xenograft growth by rhEndostatin was 46.4%, indicating lack of efficacy. In the second experiment, the effects of rhEndostatin were much more marked than those in the first experiment, with an MIR of 60.7%. The mean relative tumor weight in the treated group (n = 6) in the second experiment was significantly less than that in controls (n = 10) on days 2, 4, and 6 (P <.01) as well as on days 8 and 10 (P <.05). Nestin staining in the endothelium of control tumors (n = 2) was marked, whereas it showed a loss of fibrillar structure in rhEndostatin-treated tumors (n = 2). The number of vessels immunostained with antifactor VIII antibody was markedly reduced in tumors (n = 2) from rhEndostatin-treated mice compared with that in tumors from control animals (n = 2)., Conclusions: Continuous administration of rhEndostatin resulted in more significant tumor regression than intermittent administration of the agent in the same model. This indicates that rhEndostatin, if administered in continuous fashion, could become an effective agent for treating patients with neuroblastoma in the future.

Chromogranin A (CgA) is transported restrictedly to secretory granules in neuroendocrine cells. In addition to pH- and Ca(2+)-dependent aggregation, CgA is known to bind to a number of vesicle matrix proteins. Because the binding-prone property of CgA with secretory proteins may be essential for its targeting to secretory granules, we screened its binding partner proteins using a yeast two-hybrid system. We found that CgA bound to secretogranin III (SgIII) by specific interaction both in vitro and in endocrine cells. Localization analysis showed that CgA and SgIII were coexpressed in pituitary and pancreatic endocrine cell lines, whereas SgIII was not expressed in the adrenal glands and PC12 cells. Immunoelectron microscopy demonstrated that CgA and SgIII were specifically colocalized in large secretory granules in male rat gonadotropes, which possess large-type and small-type granules. An immunocytochemical analysis revealed that deletion of the binding domain (CgA 48-111) for SgIII missorted CgA to the constitutive pathway, whereas deletion of the binding domain (SgIII 214-373) for CgA did not affect the sorting of SgIII to the secretory granules in AtT-20 cells. These findings suggest that CgA localizes with SgIII by specific binding in secretory granules in SgIII-expressing pituitary and pancreatic endocrine cells, whereas other mechanisms are likely to be responsible for CgA localization in secretory granules of SgIII-lacking adrenal chromaffin cells and PC12 cells.

Activins expressed in progenitor cells of the pancreas regulate differentiation of endocrine cells during development. Neogenesis of beta-cells takes place in adult animals under some conditions, and beta-cells are thought to arise from precursors locating in the pancreatic duct. In the present study, we investigated whether or not activins are expressed in the duct where beta-cell neogenesis is initiated. mRNA for the beta(A)- and beta(B)-subunits was expressed in isolated mouse pancreatic ducts. Immunohistochemically, the beta(A)-subunit was detected in the pancreatic duct and colocalized with cytokeratin, a marker of ductal cells. The beta(A)-subunit was also expressed in nestin-positive cells in the duct. Likewise, the beta(B)-subunit was detected in the pancreatic duct. In addition, mRNA for the type II and type IIB activin receptors was expressed in the duct. Expression of mRNA for two activin subunits was markedly increased after streptozotocin injection. Similarly, the mRNA expression was up-regulated after partial pancreatectomy. These results indicate that activins are expressed in the pancreatic duct and are up-regulated shortly after the reduction of the beta-cell mass. Induction of activins in the duct may be a critical step in the initiation of beta-cell neogenesis.

DNA methylation of an imprinted control region (ICR) directs the allele-specific and reciprocal expression of the mouse H19 and the insulin-like growth factor 2 (Igf2) genes, mediated by controlling enhancer access. The ICR shows enhancer blocking activity through CTCF binding to an unmethylated sequence. The unmethylated state of the maternal ICR is maintained throughout development after establishment in the germ line; however, little is known of the molecular mechanisms that regulate DNA methylation. Hence, in this study we show that a dyad Oct-binding sequence (DOS) in the ICR mediates the demethylation of low-density methylation but not hypermethylation and is required to maintain the unmethylated state against the tendency for de novo methylation within the ICR in the embryonic carcinoma cell line P19. Furthermore, we also reveal that the unmethylated state of at least one CTCF-binding site within the ICR is under the control of DOS. Our results suggest that the ICR, as a CTCF-dependent insulator, requires DOS as well as CTCF-binding sites and that DOS maintains the maternal specific unmethylated state of the ICR at postimplantation stages.

We recently identified a novel set of Rab and its effector, Rab27a/granuphilin, that possibly regulates the exocytosis of insulin-containing, dense core granules in pancreatic beta-cells. In the present study we characterized another isoform, Rab27b, to further investigate the function of the Rab27 subfamily. Among the tissues examined, Rab27b is most abundantly expressed in pituitary tissue, where Rab27a is preferentially expressed. It is also significantly expressed in brain and spleen, where Rab27a is minimally expressed. Rab27a and Rab27b are differentially expressed in pituitary cell types that secrete different peptide hormones. Rab27b associates with secretory granules and granuphilin in the pituitary endocrine cell line AtT20. Furthermore, overexpression of its inactive mutant, Rab27b N133I, significantly inhibits basal and forskolin-induced ACTH secretion in AtT20 cells. These findings indicate that Rab27b is involved in pituitary hormone secretion, which further supports the idea that members of the Rab27 subfamily regulate the exocytosis of dense core granules containing peptide hormones in endocrine cells.

Nestin is one of the intermediate filaments abundantly produced in the developing central nervous system and somites in the embryonic stage. Nestin is also reportedly detected in gliomas/glioblastomas. We retested nestin expression in brain tumors having a range of malignancy grades using immunostaining. The intensity of nestin immunostaining roughly paralleled the malignancy grade of the gliomas. However, many tumors were negative for nestin immunostaining, while nestin immunostaining was invariably detected in tumor endothelium regardless of glioma malignancy grades or brain tumor types. We suspected that angiogenic epithelial cells may express nestin, and we found that nestin was highly positive in bovine aortic endothelial cells in static culture. However, nestin expression decreased when the endothelial cells underwent laminar shear stress flow, under which endothelial cells exhibit differentiated features and a decreased rate of growth. Because nestin is highly expressed in growing endothelial cells, we examined its expression in hemangioblastomas because hemangioblasts are thought to be a precursor for angiogenic epithelial cells. As expected, nestin immunostained strongly in all four samples of hemangioblastomas. We suggest that nestin is not only a marker for neuroepithelial stem cells and glioma cells but also for tumor endothelial cells during rapid growth.

The disposition of TAK-044 (cyclo[D-alpha-aspartyl-3-[(4-phenylpiperazin-1-yl)carbonyl]-L-alanyl-L- alpha-aspartyl-D-2-(2-thienyl) glycyl-L-leucyl-D-tryptophyl] disodium, CAS 157380-72-8), a new endothelin antagonist, was studied in rats and dogs by using 14C-labeled drug ([14C]TAK-044). After a single intravenous administration of [14C]TAK-044 at 3 mg/kg to rats and dogs, the concentrations of TAK-044 in plasma declined biphasically; t1/2 alpha and t1/2 beta were 0.03 and 1.10 h in rats, and 0.06 and 0.57 h in dogs, respectively. Plasma clearance and the volume of distribution at steady-state for TAK-044 were 1.66 l/h/kg and 2.09 l/kg in rats, 2.37 l/h/kg and 0.50 l/kg in dogs, respectively. In rats, TAK-044 was distributed widely into tissues, but the 14C concentrations in tissues except for the liver, kidney, and intestine were lower than that in plasma. The in vitro protein binding amounted to 91 to 92% in rat plasma and 88 to 90% in dog plasma. TAK-044 was hardly distributed into the erythrocytes of either species. TAK-044 was hardly metabolized, the radioactivity in plasma and excreta being mostly unchanged compound. Elimination of the radioactivity from the body was almost completed within 48 h in either species. The dosed radioactivity was excreted mostly in the feces via the hepatobiliary route. The rate of excretion of TAK-044 in the bile was dose-dependently prolonged.

Parathyroid hormone-related protein (PTHrP) is frequently produced in pancreatic endocrine tumors. PTHrP is synthesized as the precursor pro-PTHrP and undergoes a series of posttranslational processing reactions, among which cleavage of a 12 amino acid sequence from its precursor is crucial for the biological activation of PTHrP. This cleavage is catalyzed by furin, a proprotein-processing endoprotease that cleaves the consensus sequence -Arg-X-(Lys/Arg)-Arg-X-. We previously reported that furin is highly expressed in rat pancreatic islets during the perinatal stage and that the expression of furin in pancreatic-cells induces faster cell growth. From this, we postulated that furin may be co-expressed with PTHrP in insulinomas. We immunostained insulin, PTHrP, and furin in 21 human pancreatic endocrine tumors: 10 insulinomas, 5 VIPomas, 4 gastrinomas, and 2 somatostatinomas. Of these 21 endocrine tumors, furin was positively stained in all 10 insulinomas. Likewise, PTHrP was detected in the same insulinomas. We found one VIPoma and one gastrinoma contained a few insulin-positive cells scatteringly, which were also positive for furin and PTHrP. But other non-insulinoma endocrine tumors did not display furin and PTHrP positivity. We conclude that furin and its substrate pro-PTHrP are co-expressed specifically in insulinomas.