In vivo-stable bis-iminobiotin for targeted radionuclide delivery with the mutant streptavidin.

Targeted delivery of radionuclides to tumors is significant in theranostics applications for precision medicine. Pre-targeting, in which a tumor-targeting vehicle and a radionuclide-loaded effector small molecule are administered separately, holds promise since it can reduce unnecessary internal radiation exposure of healthy cells and can minimize radiation decay. The success of the pre-targeting delivery requires an in vivo-stable tumor-targeting vehicle selectively binding to tumor antigens and an in vivo-stable small molecule effector selectively binding to the vehicle accumulated on the tumor. We previously reported a drug delivery system composed of a low-immunogenic streptavidin with weakened affinity to endogenous biotin and a bis-iminobiotin with high affinity to the engineered streptavidin. It was, however, unknown whether the bis-iminobiotin is stable in vivo when administered alone for the pre-targeting applications. Here we report a new in vivo-stable bis-iminobiotin derivative. The keys to success were the identification of the degradation site of the original bis-iminobiotin treated with mouse plasma and the structural modification of the degradation site. We disclosed the successful pre-targeting delivery of astatine-211 (211At), α-particle emitter, to the CEACAM5-positive tumor in xenograft mouse models.

1-(N,N-Dialkylcarbamoyl)-1,1-difluoromethanesulfonyl ester as a stable and effective precursor for a neopentyl labeling group with astatine-211.

Radiohalogens with a short half-life are useful radioisotopes for radiotheranostics. Astatine-211 is an α-emitting radiohalogen and is expected to be applicable to targeted α therapy. A neopentyl labeling group is an effective hydrophilic labeling unit for various radiohalogens, which includes 211At. In this study, a 1-(N,N-dialkylcarbamoyl)-1,1-difluoromethanesulfonyl (CDf) ester was developed as a stable precursor for labeling with 211At, 77Br and 125I through a neopentyl labeling group. The CDf ester remained stable in an acetonitrile solution at room temperature and enabled the successful syntheses of 211At-labeled compounds in a highly radiochemical conversion in the presence of K2CO3. 77Br- and 125I-labeled compounds can be prepared from the CDf ester without a base. The utility of the CDf ester was demonstrated in the synthesis of a benzylguanidine with a neopentyl 211At-labeling group. The developed method afforded a 32% radiochemical yield of 211At-labeled benzylguanidine. However, a partial deastatination was observed under acidic conditions during the removal of an N-Boc protecting group. Deprotecting these groups under milder acidic conditions may improve the radiochemical yield. In conclusion, the CDf ester facilitates the syntheses of 211At, 125I and 77Br-labeled compounds that use a neopentyl labeling group for radiotheranostic applications. Further optimization of protecting groups and reaction conditions should enhance the total radiochemical yield of the 211At-labeled compounds.

Growth capability of epidemic influenza viruses in Japan since the 2009 H1N1 pandemic.

The correlation of viral growth capability (n = 156) with the viral load in nasopharyngeal swabs (n = 76) was assessed. Epidemic influenza A/H1N1, A/H3N2, and B viruses showed a wide range of growth capability (104-1011 copies/mL) in Madin-Darby canine kidney cells. The growth was correlated with the nasopharyngeal viral load (r = 0.53). Six selected strains showed growth-dependent cell death (r = 0.96) in a growth kinetics assay. Epidemic influenza viruses exhibit a wide range of growth capability. Growth capability should be considered one of the key factors in disease prognosis.

Preliminary Evaluation of Astatine-211-Labeled Bombesin Derivatives for Targeted Alpha Therapy.

There are various diagnostic and therapeutic agents for prostate cancer using bombesin (BBN) derivatives, but astatine-211 (211At)-labeled BBN derivatives have yet to be studied. This study presented a preliminary evaluation of 211At-labeled BBN derivative. Several nonradioactive iodine-introduced BBN derivatives (IB-BBNs) with different linkers were synthesized and their binding affinities measured. Because IB-3 exhibited a comparable affinity to native BBN, [211At]AB-3 was synthesized and the radiochemical yields of [211At]AB-3 was 28.2 ± 2.4%, with a radiochemical purity of >90%. The stability studies and cell internalization/externalization experiments were performed. [211At]AB-3 was taken up by cells and internalized; however, radioactivity effluxed from cells over time. In addition, the biodistribution of [211At]AB-3, with and without excess amounts of BBN, were evaluated in PC-3 tumor-bearing mice. Despite poor stability in murine plasma, [211At]AB-3 accumulated in tumor tissue (4.05 ± 0.73%ID/g) in PC-3 tumor-bearing mice, which was inhibited by excess native BBN (2.56 ± 0.24%ID/g). Accumulated radioactivity in various organs is probably due to free 211At. Peptide degradation in murine plasma and radioactivity efflux from cells are areas of improvement. The development of 211At-labeled BBN derivatives requires modifying the BBN sequence and preventing deastatination.

Toxicity of dihydroxyacetone is exerted through the formation of methylglyoxal in Saccharomyces cerevisiae: effects on actin polarity and nuclear division.

Dihydroxyacetone (DHA) is the smallest ketotriose, and it is utilized by many organisms as an energy source. However, at higher concentrations, DHA becomes toxic towards several organisms including the budding yeast Saccharomyces cerevisiae In the present study, we show that DHA toxicity is due to its spontaneous conversion to methylglyoxal (MG) within yeast cells. A mutant defective in MG-metabolizing enzymes (glo1Δgre2Δgre3Δ) exhibited higher susceptibility to DHA. Intracellular MG levels increased following the treatment of glo1Δgre2Δgre3Δ cells with DHA. We previously reported that MG depolarized the actin cytoskeleton and changed vacuolar morphology. We herein demonstrated the depolarization of actin and morphological changes in vacuoles following a treatment with DHA. Furthermore, we found that both MG and DHA caused the morphological change in nucleus, and inhibited the nuclear division. Our results suggest that the conversion of DHA to MG is a dominant contributor to its cytotoxicity.

Complexes of myo-Inositol-Hexakisphosphate (IP6) with Zinc or Lanthanum for the Decorporation of Radiocesium.

Radioactive nuclides leak into the surrounding environment after nuclear power plant disasters, such as the Chernobyl accident and the Fukushima Daiichi Nuclear Power Plant disaster. Cesium-137 (137Cs) (t1/2=30.1 year), a water-soluble radionuclide with a long physical half-life, contaminates aquatic ecosystems and food products. In humans, 137Cs concentrates in muscle tissue and has a long biological half-life, indicating it may be harmful. myo-Inositol-hexakisphosphate (IP6) is a compound found in grain, beans, and oil seeds. IP6 has the ability to form insoluble complexes with metals, including lanthanum (La) and zinc (Zn). We hypothesized that La-IP6 and Zn-IP6 may promote the elimination of 137Cs from the body through the adsorption of La-IP6 and Zn-IP6 to 137Cs in the gastrointestinal tract. Therefore, in this study, we evaluated the adsorptive capacity of La-IP6 and Zn-IP6 complexes with 137Cs in vitro and in vivo. La-IP6 and Zn-IP6 complexes were stable in acidic solution (pH 1.2) at 37°C. In vitro binding assays indicated that La-IP6 and Zn-IP6 complexes adsorbed 137Cs, with the adsorption capacity of Zn-IP6 to 137Cs greater than that of La-IP6. To evaluate the usefulness of La-IP6 and Zn-IP6 in vivo, La-IP6 or Zn-IP6 was administrated to mice after intravenous injection of 137Cs. However, the biodistribution of 137Cs in the La-IP6 treated group and the Zn-IP6 treated group was nearly identical to the non-treated control group, indicating that La-IP6 and Zn-IP6 were not effective at promoting the elimination of 137Cs in vivo.

Radiolabeled apoptosis imaging agents for early detection of response to therapy.

Since apoptosis plays an important role in maintaining homeostasis and is associated with responses to therapy, molecular imaging of apoptotic cells could be useful for early detection of therapeutic effects, particularly in oncology. Radiolabeled annexin V compounds are the hallmark in apoptosis imaging in vivo. These compounds are reviewed from the genesis of apoptosis (cell death) imaging agents up to recent years. They have some disadvantages, including slow clearance and immunogenicity, because they are protein-based imaging agents. For this reason, several studies have been conducted in recent years to develop low molecule apoptosis imaging agents. In this review, radiolabeled phosphatidylserine targeted peptides, radiolabeled bis(zinc(II)-dipicolylamine) complex, radiolabeled 5-fluoropentyl-2-methyl-malonic acid (ML-10), caspase-3 activity imaging agents, radiolabeled duramycin, and radiolabeled phosphonium cation are reviewed as promising low-molecular-weight apoptosis imaging agents.

Novel nasogastric tube-related criteria for urgent endoscopy in nonvariceal upper gastrointestinal bleeding.

BACKGROUND: Patients with active upper gastrointestinal bleeding (UGIB) require urgent endoscopy, but appropriate criteria for urgent endoscopy in these patients have not yet been established. AIMS: The goal of this study is to establish a simple system for the selection of UGIB patients who may benefit from urgent endoscopy. METHODS: Of the 335 patients who required emergency hospitalization for UGIB from May 2010 to March 2012 at Nagoya Daini Red Cross Hospital, 166 patients who underwent placement of a nasogastric tube (NGT) were retrospectively identified. Active bleeding on the endoscopic image was used as an endpoint that reflected the need for urgent endoscopy. RESULTS: The ratio of the heart rate to the systolic blood pressure (HR/SBP ratio) and aspiration of fresh or dark red fluid from the NGT [NGT(+)] were significant predictors of active bleeding in the univariate analysis [HR/SBP ratio, P=0.016; NGT(+), P<0.001]. The HR/SBP ratio [odds ratio (OR) 8.118; 95% confidence intervals (CI) 1.696-38.850; P=0.009] and NGT(+) (OR 4.630; 95% CI 2.092-10.204; P<0.001) were also significantly associated with active bleeding in the multivariate analysis. Moreover, receiver operating characteristic analysis revealed a setting with HR/SBP ratio>1.4 or NGT(+) to be optimal criteria to predict active bleeding. These criteria were associated with a sensitivity of 64.9% (24/37) and a specificity of 76.7% (99/129) for the prediction of active bleeding; consequently, they are superior to the sensitivity and specificity of previously proposed criteria. CONCLUSIONS: A novel and simple criteria system using NGT(+) and HR/SBP is a good predictor of the need for urgent endoscopy in patients with nonvariceal UGIB.

Excess Glucose Impedes the Proliferation of Skeletal Muscle Satellite Cells Under Adherent Culture Conditions.

Glucose is a major energy source consumed by proliferating mammalian cells. Therefore, in general, proliferating cells have the preference of high glucose contents in extracellular environment. Here, we showed that high glucose concentrations impede the proliferation of satellite cells, which are muscle-specific stem cells, under adherent culture conditions. We found that the proliferation activity of satellite cells was higher in glucose-free DMEM growth medium (low-glucose medium with a glucose concentration of 2 mM) than in standard glucose DMEM (high-glucose medium with a glucose concentration of 19 mM). Satellite cells cultured in the high-glucose medium showed a decreased population of reserve cells, identified by staining for Pax7 expression, suggesting that glucose concentration affects cell fate determination. In conclusion, glucose is a factor that decides the cell fate of skeletal muscle-specific stem cells. Due to this unique feature of satellite cells, hyperglycemia may negatively affect the regenerative capability of skeletal muscle myofibers and thus facilitate sarcopenia.

Delta-like 1 homolog (DLK1) as a possible therapeutic target and its application to radioimmunotherapy using 125I-labelled anti-DLK1 antibody in lung cancer models (HOT1801 and FIGHT004).

OBJECTIVES: Delta-like 1 homolog (DLK1) is a non-canonical Notch ligand known to be expressed in several cancers but whose role in lung cancer is not yet fully understood. We sought to confirm DLK1 expression in small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC), and to examine DLK1's clinical significance. Furthermore, we examined the possible utility of DLK1 as a novel target in radioimmunotherapy (RIT). METHODS: We retrospectively assessed the correlation between clinical features and DLK1 expression by immunohistochemistry in resected specimens from 112 patients with SCLC and 101 patients with NSCLC. Moreover, we performed cell and animal experiments, and examined the possibility of RIT targeting DLK1 in SCLC using iodine-125 (125I) -labeled anti-DLK1 antibody, knowing that 125I can be replaced with the alpha-particle-emitter astatine-211 (211At). RESULTS: In SCLC and NSCLC, 20.5 % (23/112) and 16.8 % (17/101) of patients (respectively) had DLK1-positive tumors. In NSCLC, DLK1 expression was associated with recurrence-free survival (P < 0.01) but not with overall survival. In SCLC, there was no association between DLK1 expression and survival. In addition, 125I-labeled anti-DLK1 antibody specifically targeted DLK1 on human SCLC tumor cell lines. Furthermore, 125I-labeled anti-DLK1 antibody was incorporated into tumor tissue in a mouse model. CONCLUSION: A proportion of SCLC and NSCLC exhibits DLK1 expression. As a clinical feature, DLK1 expression could be a promising prognostic factor for recurrence in patients with resected NSCLC. In addition, DLK1 could serve as a new therapeutic target, including RIT, as suggested by our pilot study using a radiolabeled anti-DLK1 antibody in SCLC.

Methylglyoxal inhibits nuclear division through alterations in vacuolar morphology and accumulation of Atg18 on the vacuolar membrane in Saccharomyces cerevisiae.

Methylglyoxal (MG) is a natural metabolite derived from glycolysis, and it inhibits the growth of cells in all kinds of organisms. We recently reported that MG inhibits nuclear division in Saccharomyces cerevisiae. However, the mechanism by which MG blocks nuclear division remains unclear. Here, we show that increase in the levels of phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2) is crucial for the inhibitory effects of MG on nuclear division, and the deletion of PtdIns(3,5)P2-effector Atg18 alleviated the MG-mediated inhibitory effects. Previously, we reported that MG altered morphology of the vacuole to a single swelling form, where PtdIns(3,5)P2 accumulates. The changes in the vacuolar morphology were also needed by MG to exert its inhibitory effects on nuclear division. The known checkpoint machinery, including the spindle assembly checkpoint and morphological checkpoint, are not involved in the blockade of nuclear division by MG. Our results suggest that both the accumulation of Atg18 on the vacuolar membrane and alterations in vacuolar morphology are necessary for the MG-induced inhibition of nuclear division.

Human dosimetry of free 211At and meta-[211At]astatobenzylguanidine (211At-MABG) estimated using preclinical biodistribution from normal mice.

BACKGROUND: 211At is one of the ideal nuclides for targeted radionuclide therapies (TRTs). Meta-[211At]astatobenzylguanidine (211At-MABG) has been proposed for the treatment of pheochromocytoma. To effectively use these radiopharmaceuticals, dosimetry must be performed. It is important to determine the absorbed doses of free 211At and 211At-MABG to determine the organs that may be at risk when using TRTs. The aim of this study was to estimate human dosimetry from preclinical biodistribution of free 211At and 211At-MABG in various organs in normal mice. METHODS: Male C57BL/6 N mice were administered 0.13 MBq of free 211At or 0.20 MBq of 211At-MABG by tail-vein injection. The mice were sacrificed at 5 min, and at 1, 3, 6, and 24 h after the injection (n = 5 for each group). The percentage of injected activity per mass in organs and blood (%IA/g) was determined. The human absorbed doses of free 211At and 211At-MABG were calculated using the Organ Level INternal Dose Assessment/EXponential Modeling (OLINDA/EXM) version 2.0 and IDAC-Dose 2.1. RESULTS: High uptake of free 211At was observed in the lungs, spleen, salivary glands, stomach, and thyroid. The absorbed doses of free 211At in the thyroid and several tissues were higher than those of 211At-MABG. The absorbed doses of 211At-MABG in the adrenal glands, heart wall, and liver were higher than those of free 211At. CONCLUSIONS: The absorbed doses of 211At-MABG in organs expressing the norepinephrine transporter were higher than those of free 211At. In addition, the biodistribution of free 211At was different from that of 211At-MABG. The absorbed dose of free 211At may help predict the organs potentially at risk during TRTs using 211At-MABG due to deastatination.

Possibility of cancer-stem-cell-targeted radioimmunotherapy for acute myelogenous leukemia using 211At-CXCR4 monoclonal antibody.

To explore stem-cell-targeted radioimmunotherapy with α-particles in acute myelogenous leukemia (AML), pharmacokinetics and dosimetry of the 211At-labeled anti-C-X-C chemokine receptor type 4 monoclonal antibody (211At-CXCR4 mAb) were conducted using tumor xenografted mice. The biological half-life of 211At-CXCR4 mAb in blood was 15.0 h. The highest tumor uptake of 5.05%ID/g with the highest tumor-to-muscle ratio of 8.51 ± 6.14 was obtained at 6 h. Radiation dosimetry estimated with a human phantom showed absorbed doses of 0.512 mGy/MBq in the bone marrow, 0.287 mGy/MBq in the kidney, and <1 mGy/MBq in other major organs except bone. Sphere model analysis revealed 22.8 mGy/MBq in a tumor of 10 g; in this case, the tumor-to-bone marrow and tumor-to-kidney ratios were 44.5 and 79.4, respectively. The stem-cell-targeted α-particle therapy using 211At-CXCR4 mAb for AML appears possible and requires further therapeutic studies.

Development of radiolabeled bis(zinc(II)-dipicolylamine) complexes for cell death imaging.

PURPOSE: Although it has been traditionally surmised that phosphatidylserine (PS) externalization is a hallmark of apoptosis, most other non-apoptotic modes of cell death, such as necrosis, are also associated with PS externalization. Bis(zinc-dipicolylamine) (ZnDPA) complexes have been reported to exhibit affinity for PS. The present study aimed to develop novel radiolabeled ZnDPA derivatives for cell death imaging in tumor after treatment with anticancer drugs. METHODS: [125I]IB-EG2-ZnDPA and [99mTc]Tc-MAG3-EG2-ZnDPA were designed and prepared. The stabilities of these radiotracers were determined in 0.1 M phosphate buffer (pH 7.4) or murine plasma at 37 °C, and their 1-octanol/water partition coefficients (logP) were measured. The uptake of radioactivity in cancer cells, which were preincubated in a normal medium or in a medium containing 5-FU, was measured after incubation with radiotracers. Accumulation of [99mTc]Tc-MAG3-EG2-ZnDPA in the tumor was evaluated in tumor-bearing mice treated with or without 5-FU, and then TUNEL staining was performed to detect dead cells in the tumor tissue sections. RESULTS: The radiochemical purities of [125I]IB-EG2-ZnDPA and [99mTc]Tc-MAG3-EG2-ZnDPA exceeded 95%. Although [125I]IB-EG2-ZnDPA gradually decomposing with time, more than 90% of [99mTc]Tc-MAG3-EG2-ZnDPA remained in its intact form in phosphate buffer through 6 h of incubation. Neither [125I]IB-EG2-ZnDPA nor [99mTc]Tc-MAG3-EG2-ZnDPA decomposed so much after 6-h incubation in murine plasma. [125I]IB-EG2-ZnDPA could not specifically recognize PS on the cell surface because of its high lipophilicity. Conversely, [99mTc]Tc-MAG3-EG2-ZnDPA accumulated in cancer cells after treatment with an anticancer drug both in vitro and in vivo, and its accumulation was correlated with the number of TUNEL-positive cells. However, the biodistribution of [99mTc]Tc-MAG3-EG2-ZnDPA was not suitable for imaging because of its low accumulation in tumor and high uptake in abdomen organs. CONCLUSION: [99mTc]Tc-MAG3-EG2-ZnDPA could be useful for the early detection of treatment effects after chemotherapy. Since the signal-to-noise ratio is not enough for single photon emission computed tomography imaging, further modification is needed to improve its biodistribution and affinity for PS.

Complexes of myo-inositol-hexakisphosphate (InsP6) with zinc or lanthanum to enhance excretion of radioactive strontium from the body.

90Sr, which was released into the atmosphere and the ocean following the Chernobyl and Fukushima Daiichi nuclear power plant disasters, is an important nuclear fission element. Compounds that inhibit the absorption of 90Sr into the bloodstream and enhance its elimination can be beneficial in decreasing the absorbed radiation dose in people exposed to 90Sr. Recently, we prepared complexes of myo-inositol-hexakisphosphate (InsP6) with zinc or lanthanum as decorporation agents. These complexes, called Zn-InsP6 and La-InsP6 respectively, are insoluble in water and can potentially chelate additional metal cations. Hypothesizing that these complexes can assist the excretion of 90Sr from the body, we evaluated them using 85Sr instead of 90Sr. In in vitro binding experiments, Zn-InsP6 showed higher strontium adsorption capacity than La-InsP6. We then performed in vivo biodistribution experiments of Zn-InsP6 in mice after oral administration of 85SrCl2. Mice treated with Zn-InsP6 showed significantly lower bone accumulation of radioactivity than mice in a non-treatment control group. Zn-InsP6 adsorbed radiostrontium in the gastrointestinal tract, inhibited this ion's absorption into the bloodstream, and enhanced its excretion in the feces. Therefore, Zn-InsP6 appears to be a promising 90Sr "decorporation" agent.

Evidence for acute contraction-induced myokine secretion by C2C12 myotubes.

Skeletal muscle is considered a secretory organ that produces bioactive proteins known as myokines, which are released in response to various stimuli. However, no experimental evidence exists regarding the mechanism by which acute muscle contraction regulates myokine secretion. Here, we present evidence that acute contractions induced myokine secretion from C2C12 myotubes. Changes in the cell culture medium unexpectedly triggered the release of large amounts of proteins from the myotubes, and these proteins obscured the contraction-induced myokine secretion. Once protein release was abolished, the secretion of interleukin-6 (IL-6), the best-known regulatory myokine, increased in response to a 1-hour contraction evoked by electrical stimulation. Using this experimental condition, intracellular calcium flux, rather than the contraction itself, triggered contraction-induced IL-6 secretion. This is the first report to show an evidence for acute contraction-induced myokine secretion by skeletal muscle cells.

Early induced, high-level interleukin-6 expression in the rat peritoneal cavity into which a hepatotoxicant carbon tetrachloride was administered.

IL-6 induction depending on the mode of carbon tetrachloride (CCl4) administration was investigated in rats. After the intraperitoneal (i.p.) administration of CCl4 in 50% corn oil at 1.0 ml/kg body weight, IL-6 level markedly increased in plasma and peaked at 4h. TNF-alpha and IL-1beta levels gradually increased, reaching the maximum at 24h. IL-10 level transiently peaked at 4h and then decreased, but later further increased, reaching the second peak at 24h. Plasma alanine aminotransferase (ALT) and sorbitol dehydrogenase (SDH) activities peaked at 24h. As the vehicle-to-CCl4 ratio increased, the level of IL-6 decreased and the activities of ALT and SDH increased. After oral CCl4 administration, IL-6 was not significantly detected. IL-6 level in peritoneal exudate fluid (PEF) increased simultaneously with plasma IL-6 level after i.p. CCl4 administration, but the total amount of PEF IL-6 was 37-fold as much as that of plasma IL-6, in contrast to the result that the total amount of plasma IL-6 was 19-fold as much as that of PEF IL-6 after i.p. lipopolysaccharide administration. These results suggest that i.p. administration of CCl4 dissolved in a small amount of vehicle selectively induces a high production of IL-6 in the peritoneal cavity early after the administration. Since IL-6 is a protective cytokine against hepatotoxicity, its induction should be taken into consideration during analysis of data obtained using the CCl4-induced liver injury model.

Nesfatin-1 inhibits voltage gated K+ channels in pancreatic beta cells.

The anorexigenic neuropeptide NEFA/nucleobindin 2 (NUCB2)/nesfatin-1-containing neurons are distributed in the brain regions involved in feeding regulation. In spite of the growing knowledge of its physiological functions through extensive studies, its molecular mechanism of reaction, including its receptor, remains unknown. NUCB2/nesfatin-1 is also involved in various peripheral regulations, including glucose homeostasis. In pancreatic beta-cells, NUCB2/nesfatin-1 is reported to enhance glucose-stimulated insulin secretion (GSIS) but its exact mechanism remains unknown. To clarify this mechanism, we measured the effect of nesfatin-1 on the electrical activity of pancreatic beta-cells. Using mouse primary beta cells, we measured changes in the ATP-sensitive K+ (KATP) channel current, the voltage-gated K+ (Kv) channel current, and insulin secretion upon application of nesfatin-1. Nesfatin-1 inhibited the Kv channel, but KATP channel activity was unaffected. Nesfatin-1 enhanced insulin secretion to a same level as Kv channel blocker tetraethylammonium (TEA). The effect was not further enhanced when nesfatin-1 and TEA were applied simultaneously. The inhibition binding assay with [125I]nesfatin-1 in Kv2.1 channels, major contributor of Kv current in beta cell, expressing HEK239 cells indicated the binding of nesfatin-1 on Kv2.1 channel. Because Kv channel inhibition enhances insulin secretion under high glucose conditions, our present data suggest a possible mechanism of nesfatin-1 on enhancing GSIS through regulation of ion channels rather than its unidentified receptor.

Nonylphenol enhances apoptosis induced by serum deprivation in PC12 cells.

Although nonylphenol is well known as an endocrine disrupting chemical, there is little information concerning biological effect of nonylphenol. In this study, we investigated effect of nonylphenol on apoptosis induced by serum deprivation in PC12 cells using TUNEL and DNA fragmentation assays. In addition, changes in contents of proapoptotic factors, Bad and Bax, and antiapoptotic factor, Bcl-2, and enzyme activity of caspase-3 were studied. Below 100 ng/ml of nonylphenol increased TUNEL signals, DNA fragmentation and content of proapoptotic factor, Bad as compared to those by serum deprivation without nonylphenol. Furthermore, addition of nonylphenol enhanced caspase-3 activity and Z-VAD, caspase-3 inhibitor, diminished such effect. These results indicated that below 100 ng/ml of nonylphenol enhanced apoptosis induced by serum deprivation via caspase-3 activation in PC12 cell.

Development and evaluation of a novel (99m)tc-labeled annexin A5 for early detection of response to chemotherapy.

(99m)Tc-HYNIC-annexin A5 can be considered as a benchmark in the field of apoptosis imaging. However, (99m)Tc-HYNIC-annexin A5 has characteristics of high uptake and long retention in non-target tissues such as kidney and liver. To minimize this problem, we developed a novel (99m)Tc-labeled annexin A5 using a bis(hydroxamamide) derivative [C3(BHam)2] as a bifunctional chelating agent, and evaluated its usefulness as an imaging agent for detecting apoptosis. The amino group of C3(BHam)2 was converted to a maleimide group, and was coupled to thiol groups of annexin A5 pretreated with 2-iminothiolane. (99m)Tc labeling was performed by a ligand exchange reaction with (99m)Tc-glucoheptonate. Biodistribution experiments for both (99m)Tc-C3(BHam)2-annexin A5 and (99m)Tc-HYNIC-annexin A5 were performed in normal mice. In addition, in tumor-bearing mice, the relationship between the therapeutic effects of chemotherapy (5-FU) and the tumor accumulation of (99m)Tc-C3(BHam)2-annexin A5 just after the first treatment of 5-FU was evaluated. (99m)Tc-C3(BHam)2-annexin A5 was prepared with a radiochemical purity of over 95%. In biodistribution experiments, (99m)Tc-C3(BHam)2-annexin A5 had a much lower kidney accumulation of radioactivity than (99m)Tc-HYNIC-annexin A5. In the organs for metabolism, such as liver and kidney, radioactivity after the injection of (99m)Tc-HYNIC-annexin A5 was residual for a long time. On the other hand, radioactivity after the injection of (99m)Tc-C3(BHam)2-annexin A5 gradually decreased. In therapeutic experiments, tumor growth in the mice treated with 5-FU was significantly inhibited. Accumulation of (99m)Tc-C3(BHam)2-annexin A5 in tumors significantly increased after 5-FU treatment. The accumulation of radioactivity in tumor correlated positively with the counts of TUNEL-positive cells. These findings suggest that (99m)Tc-C3(BHam)2-annexin A5 may contribute to the efficient detection of apoptotic tumor response after chemotherapy.