BPB Reports

2019 - Vol. 2 No. 6

2019 - Vol. 2

Regular Article
Protein Kinase C Regulates the Citrate Transport via Na+-Coupled Citrate Transporter NaCT in HepG2 Cells Vol.2, No.6, p.134-140
Maya Goto , Yusuke Kono , Ayako Yuki , Haruka Nishimura , Mizuki Ikawa , Kanta Ohno , Takuya Fujita
Received: November 01, 2019
Accepted: December 23, 2019
Released: December 31, 2019
Abstract Full Text PDF[1M]

Citrate, an intermediate of tricarboxylic acid cycle, plays a crucial role for the generation of biochemical energy and synthesis of fatty acids and cholesterol in liver. The cellular uptake of citrate is mediated by Na+-coupled di- and tricarboxylate transporters, particularly NaCT. Since NaCT expression level in liver is closely related to the pathogenesis of metabolic diseases, such as non-alcoholic fatty liver disease. Therefore, it is important to elucidate the regulation mechanism of NaCT function in liver. In this study, we focused on protein kinase C (PKC), and evaluated the influence of PKC activation on the citrate transport in human hepatocellular carcinoma HepG2 cells. The uptake of citrate in HepG2 cells depended on Na+, and it also occurred via a saturable process. Its Michaelis constant (Km) and maximal velocity (Vmax) was 5.12 mM and 106 nmol/mg protein/30 min, respectively. These results suggest that the citrate transport in HepG2 cells is primarily mediated by NaCT. In addition, we observed that the Na+-dependent citrate uptake in HepG2 cells was significantly decreased by the preincubation of the cells with phorbol 12-myristate 13-acetate (PMA), a PKC activator. We also found that this decrease of citrate uptake by PMA was attributed to the reduction of Vmax, without affecting Km value. These results indicate that PKC regulates the transport activity of NaCT in HepG2 cells. The present findings contribute to the elucidation of the regulation mechanism of NaCT function in hepatic metabolic diseases.

Sensitization of Gastric Cancer Cells to Irinotecan by p53 Activation Vol.2, No.6, p.130-133
Shun Zhang , Yoshinori Kohira , Hajime Orita , Momoko Ishimine , Toshiyuki Kobayashi , Sharlyn Mae Buendia Chua , Hirofumi Nakaoka , Ituro Inoue , Okio Hino , Takehiko Yokomizo , Tetsu Fukunaga , Hyeon-Cheol Lee-Okada
Received: December 11, 2019
Accepted: December 17, 2019
Released: December 27, 2019
Abstract Full Text PDF[1M]

Irinotecan (camptothecin-11 [CPT-11]) is a topoisomerase I inhibitor that has been used in the treatment of a wide spectrum of cancers including gastric cancer. Recent reports suggest that the expression of CES2, a serine hydrolase that converts irinotecan to its active compound SN-38, is regulated by the tumor-suppressor p53. In this study, we investigated whether irinotecan acted synergistically with a p53 activator nutlin-3a in human gastric cancer cells. Nutlin-3a treatment enhanced the expression of CES2 in gastric cancer cell lines with wild-type p53. However, this effect was not observed in cells with non-functional p53. Irinotecan showed synergistic antitumor effects in combination with nutlin-3a in gastric cancer cells with wild-type p53, whereas the survival of cells with non-functional p53 was not significantly affected by the presence of nutlin-3a. These results provide evidence that p53 activation can enhance the antitumor effect of irinotecan or other anticancer prodrugs activated by CES2 in gastric cancer cells through upregulation of CES2 expression.

The Efficacy of a Mattress Type Sleep Measuring Device in Analyzing Sleep in Healthy University Students: Comparison with Actigraphy Vol.2, No.6, p.125-129
Hiroshi Kawai , Yutaro Togashi , Takuya Ishibashi , Reiko Iwadate , Atsushi Mitsumoto
Received: November 15, 2019
Accepted: December 10, 2019
Released: December 24, 2019
Abstract Full Text PDF[665K]

Sleep disturbance relates to various disorders and is a significant public health issue. Evaluation of sleep quality is necessary to analyze and improve sleep quality. Polysomnography (PSG) is an efficient method for sleep analysis. However, complicated systems are required for the analysis. Also, PSG can be stressful for participants and is, therefore, not suitable for long term sleep monitoring. Sleepscan is a non-invasive mattress type sleep measuring device developed by TANITA. Sleepscan measures the participant’s heart rate, respiration, and body movement during sleep, and evaluates sleep quality objectively. We measured the sleep quality of healthy university students with Sleepscan and a widely-used sleep measuring device, actigraph. We also discussed the efficacy of using Sleepscan daily. Sleepscan detected longer sleep latency and shorter awake episodes during sleep than actigraph. Although these devices showed quite different results for some sleep variables, the sleep score recorded by Sleepscan and sleep efficiency by actigraph correlates well. Since sleep efficiency is used as a representative index for comprehensive sleep quality in actigraphy, the sleep score by Sleepscan can be an alternative index used to evaluate sleep quality objectively. Sleepscan can also analyze the depth of sleep. The deep sleep variables recorded by Sleepscan did not correlate with the sleep variables by actigraph, suggesting that these variables may represent aspects of sleep quality that cannot be detected by actigraphy. Sleepscan may be useful in analyzing sleep quality objectively more comprehensively over a long period.

Regular Article
Application of Activated Clay for Improvement of Water Quality in Wire Electric Discharge Machining Vol.2, No.6, p.119-124
Eri Nagahashi , Fumihiko Ogata , Takehiro Nakamura , Naohito Kawasaki
Received: November 25, 2019
Accepted: December 13, 2019
Released: December 23, 2019
Abstract Full Text PDF[1M]

In this study, the availability of activated clay treatment for decreasing the electrical conductivity in the real wire cut water was demonstrated. Activated clay (AC) was prepared, and its characteristics were investigated. The ability to adsorb Zn2+ and the removal ability through electrical conductivity were evaluated. It was found that the AC had a montmorillonite-like structure. Its specific surface area, micropore volume, mesopore volume, and macropore volume were 125.0 m2/g, 0.7 μL/g, 172.6 μL/g, and 13.7 μL/g, respectively. The cation exchange capacities at pH 5 and pH 10 were 56.2 and 67.2 cmol/kg, respectively. The effects of temperature, contact time, and pH of the solution on the adsorption of Zn2+ were measured. The amount of Zn2+ adsorbed by the AC increased with an increase in the adsorption temperature or in the pH. Adsorption isotherms data were fitted to the Freundlich equation compared to the Langmuir equation. Adsorption equilibrium was reached within 30 min, and kinetic data were fitted to the pseudo-second-order model compared to the pseudo-first-order model. Additionally, the AC was proven to effectively suppress the electrical conductivity. The suppression achieved by using washed AC was higher than that obtained by virgin AC. Washing AC with distilled water is useful for removing released ions (SO42-). Therefore, the column treatment packed with washed AC was evaluated in this paper. Finally, washed AC could remove Zn2+, resulting in the reduction of electrical conductivity (removal percentage is 47%). These findings provide significant information that can be useful for the removal of Zn2+ and reducing the electrical conductivity from wire cut water.

Adenovirus Fiber can Distribute Itself to the Cell Surface without Membrane Damage Vol.2, No.6, p.113-118
Anna Sato , Takamasa Hirai , Naoya Koizumi , Saya Hatakeyama , Aine Watanabe , Tetsuya Nomura , Fuminori Sakurai , Hiroyuki Mizuguchi , Naoki Utoguchi
Received: October 04, 2019
Accepted: November 22, 2019
Released: December 20, 2019
Abstract Full Text PDF[2M]

Fiber is an adenovirus (Ad) capsid protein that binds to coxsackievirus and Ad receptor. It is secreted by Ad-infected cells in the early infection stage, and it increases the permeability of the epithelial cells. Accordingly, fiber may facilitate the apical escape of Ad particles from the basolateral side in Ad-infected cells. However, its behavior in the Ad-infected cells remains unclear. Therefore, we investigated the behavior of fiber in the Adinfected cells by fluorescence microscope analysis. Results showed that a higher proportion of fiber molecules were present in the apical side compared with that in the basolateral side, and electrical resistance, which represents cell–cell adhesion, remained unaffected in the Ad-infected cells. Furthermore, the association between fiber secretion and membrane damage was analyzed using annexin V and propidium iodide staining. We observed that fiber was distributed to the membrane surface without membrane damage. In addition, fiber distribution occurred in Ad-infected cells as well as in fiber-expressing cells. Therefore, fiber can distribute itself to the cell surface, and it plays a novel role in Ad infection. Further investigation of fiber distribution would be useful to completely elucidate Ad infection mechanism and develop antiviral strategies for Ad.

Regular Article
Induction of Versican V0 Variant Synthesis by A Thrombin Receptor Agonist Peptide in Cultured Human Coronary Smooth Muscle Cells Vol.2, No.6, p.106-112
Takato Hara , Takako Wakata , Yasuyuki Fujiwara , Chika Yamamoto , Toshiyuki Kaji
Received: November 06, 2019
Accepted: November 25, 2019
Released: December 18, 2019
Abstract Full Text PDF[1M]

Versican is a large aggregating chondroitin sulfate proteoglycan that accumulates in vascular wall during atherosclerosis. This proteoglycan is particularly synthesized by arterial smooth muscle cells and contributes to atherosclerosis progression by enhancing the retention of low density lipoproteins and inducing the proliferation and migration of the cells in atherosclerotic plaques. There is a strong interrelationship between atherosclerosis and thrombosis, suggesting that thrombin—a key coagulation factor—may stimulate versican synthesis in arterial smooth muscle cells. To determine the regulation of proteoglycan synthesis by thrombin receptor agonist peptide (SFLLRN), cultured human coronary smooth muscle cells were stimulated by the peptide, and proteoglycans synthesized by the cells were characterized by biochemical techniques. The experiments indicate that SFLLRN enhances the synthesis of versican V0 variant without affecting the length and disaccharide composition of its chondroitin sulfate chains under high cell density condition. This suggests that the procoagulant state of blood may accelerate atherosclerosis progression through a high accumulation of versican V0 variant derived from arterial smooth muscle cells after the cell density becomes higher in atherosclerotic plaques.

Regular Article
DC-Based Immunotherapy Using Vascular Endothelial Cells Cultured in Conditioned Medium as a Vaccine Antigen Exerts an Anti-Tumor Effect by Inhibiting Angiogenesis Vol.2, No.6, p.99-105
Makie Yamakawa , Tetsuya Nomura , Mariko Yamagata , Takamasa Hirai , Naoya Koizumi , Kazuo Maruyama , Naoki Utoguchi
Received: November 06, 2019
Accepted: December 02, 2019
Released: December 18, 2019
Abstract Full Text PDF[2M]

Blood vessels are essential for the maintenance and growth of tumor tissues. Furthermore, tumor angiogenesis promotes metastasis, which greatly affects prognosis. Therefore, tumor blood vessels are considered an important target in cancer therapy. Cancer immunotherapy has been developed recently as a new cancer therapeutic. Notably, vaccine therapy with dendritic cells (DCs), which possess potent antigen-presenting capacities, is expected to induce tumor-associated, antigen-specific immunity. In this regard, as tumor endothelial cells (TECs) constituting tumor blood vessels are derived from endothelial cells (ECs) in the host, DC vaccine therapy targeting tumor blood vessels may have applicability in several cancer types. Thus, we attempted to develop DC vaccine therapy that targeted TEC. In our previous studies, in vitro TEC models were created by culturing normal ECs in the culture supernatants of tumor cells. Moreover, we demonstrated that the molecules’ permeability is enhanced in an in vitro TEC model compared with normal ECs. In this study, we examined whether immunotherapy using TEC-extracted proteins as vaccine antigens would be an effective cancer therapy. The results showed that DC vaccine therapy targeting TECs induced anti-tumor effects in a murine Colon-26 solid tumor model and in a lung metastases model using murine B16 melanoma cells. Moreover, anti-angiogenic effects of immunization with TECs were demonstrated. Thus, immunotherapy using the in vitro TEC model as an antigen may be an effective cancer therapeutic. In the future, identifying specific TEC antigens will help generate promising new strategies to inhibit angiogenesis.

Regular Article
Distribution of 58 Semi-Volatile Organic Chemicals in the Gas Phase and Three Particle Sizes in Indoor Air and House Dust in Residential Buildings During the Hot Season in Japan Vol.2, No.6, p.91-98
Shinji Takeuchi , Toshiko Tanaka-Kagawa , Ikue Saito , Hiroyuki Kojima , Hideto Jinno
Received: November 14, 2019
Accepted: November 20, 2019
Released: December 04, 2019
Abstract Full Text PDF[1M]

A variety of semi-volatile organic chemicals (SVOCs), such as plasticizers and flame retardants, are released into indoor air and dust from building materials, furniture, and housekeeping products in residential housing. In this study, we measured 58 SVOCs in indoor air and dust from 50 and 48 dwellings, respectively, from 19 prefectures across Japan during the hot season (from July to September). In order to reveal the current situation regarding these compounds in indoor air, we obtained indoor air samples using a newly designed four-stage multi-nozzle cascade impactor and measured the concentrations of the chemicals in the indoor air in three different particle size ranges (<2.5, 2.5-10, and >10μm), as well as a gas phase. From the results obtained using the multi-nozzle cascade impactor, smaller compounds were mainly detected in the gas phase and larger compounds were found in the particle phases. However, the three cyclic polysiloxanes, including decamethylcyclooctasiloxane (D5), with large molecules were detected in the gas phase in all of the houses. Among the 58 chemicals, D5 showed the highest median concentration (1.1 μg/m3) in the range from 0.2 to 36 μg/m3 in the indoor air samples. Our analysis of house dust revealed that di-2-ethylhexyl phthalate (DEHP) was present in all samples at the highest median concentration (590 μg/g) in the range from 200 to 6,200 μg/g. These results suggest that the residential indoor environment in Japan is mainly polluted with siloxanes in the gas phase of indoor air and by DEHP in house dust.