Papers - IKEDA Ryuji
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クラスI自主回収における医薬品SPDのトレーサビリティ分析の効果 Reviewed
関屋 裕史、緒方 豊、梶原 隆広、福永 洋子、北畑 恵理子、岩切 智美、奥村 学、池田 龍二
九州薬学会雑誌 2018.11
Language：Japanese Publishing type：Research paper (scientific journal)
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神経障害性疼痛を伴った難治性癌性疼痛に対しメサドン導入を行った3症例 Reviewed
畑中真理，平原康寿，吉川直樹，山賀昌治，柴田伸弘，船橋英樹，藤山美穂，西村亜希，三輪真砂子，田﨑智也，岩切智美，奥村学，池田龍二
九州薬学会雑誌 2018.11
Language：Japanese Publishing type：Research paper (scientific journal)
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神経・呼吸器・内分泌・代謝・糖尿病内科病棟における病棟専任薬剤師による能動的介入の調査報告 Reviewed
田﨑 智也、吉川 直樹、平原 康寿、大野 梨絵、関屋 裕史、岩切 智美、奥村 学、池田 龍二
九州薬学会雑誌 2018.11
Language：Japanese Publishing type：Research paper (scientific journal)
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Tomiyama N., Ikeda R., Nishizawa Y., Masuda S., Tajitsu Y., Takeda Y.
Oncology Letters 15 ( 6 ) 9929 - 9933 2018.6
Language：English Publishing type：Research paper (scientific journal) Publisher：Oncology Letters
© 2018, Spandidos Publications. All rights reserved. Cancer stem-like cells (CSCs), which possess the ability to self-renewal and are multipotent, are regarded as the cause of tumor formation, recurrence, metastasis and drug resistance. It is necessary to understand the properties of CSCs in order to treat them effectively. It has been previously reported that S100 family proteins, which carry calcium-binding EF-hand motifs and are associated with tumorigenic processes, serve crucial roles in maintaining cancer stem-like properties. S100A16 is upregulated in various types of cancer, including bladder, lung and pancreatic. However, the roles of S100A16 in cancer cells, particularly CSCs, are not clear. The present study investigated the roles of S100A16 in CSCs using the sphere formation assay of Yumoto cells, which are a human cervical carcinoma cell line. The mRNA expression levels were evaluated by reverse transcription-polymerase chain reaction and the protein expression levels were detected by western blot analysis. Following the sphere formation of Yumoto cells, the mRNA and protein expression level of Oct4, Nanog and S100A16 were increased compared with the control cells. Following transfection with S100A16 small interfering RNA (siRNA), the mRNA and protein expression of Oct4 and Nanog were decreased and the spheroid size was significantly decreased in the sphere formation of Yumoto cells compared with control siRNA treated cells. There was no change in the p53 mRNA expression level, whereas the p53 protein expression level, which was decreased by the sphere formation, was recovered by S100A16 knockdown. In addition, the protein expression levels of Oct4 and Nanog, which were increased in the sphere formation, were decreased by the proteasome inhibitor lactacystin. No differences were observed in the S100A16 protein expression between the presence or absence of lactacystin. These results suggest that S100A16 serves an important role in the CSCs of human cervical carcinoma and is a positive regulator of Oct4 and Nanog.
DOI： 10.3892/ol.2018.8568
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ダクラタスビル/アスナプレビル投与による肝機能障害発現の危険因子に関する後方視的調査 Reviewed
吉川 直樹, 北畑 和寛, 奥村 学, 岩切 智美, 関屋 裕史, 有森 和彦, 米澤 ゆう子, 有村 保次, 池田 龍二
医療薬学 2018.1
Language：Japanese Publishing type：Research paper (scientific journal)
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Thymidine Catabolism as a Metabolic Strategy for Cancer Survival Reviewed
Tabata S., Yamamoto M., Goto H., Hirayama A., Ohishi M., Kuramoto T., Mitsuhashi A., Ikeda R., Haraguchi M., Kawahara K., Shinsato Y., Minami K., Saijo A., Hanibuchi M., Nishioka Y., Sone S., Esumi H., Tomita M., Soga T., Furukawa T., Akiyama S.
Cell Reports 19 ( 7 ) 1313 - 1321 2017.5
Language：English Publishing type：Research paper (scientific journal) Publisher：Cell Reports
© 2017 The Author(s) Thymidine phosphorylase (TP), a rate-limiting enzyme in thymidine catabolism, plays a pivotal role in tumor progression; however, the mechanisms underlying this role are not fully understood. Here, we found that TP-mediated thymidine catabolism could supply the carbon source in the glycolytic pathway and thus contribute to cell survival under conditions of nutrient deprivation. In TP-expressing cells, thymidine was converted to metabolites, including glucose 6-phosphate, lactate, 5-phospho-α-D-ribose 1-diphosphate, and serine, via the glycolytic pathway both in vitro and in vivo. These thymidine-derived metabolites were required for the survival of cells under low-glucose conditions. Furthermore, activation of thymidine catabolism was observed in human gastric cancer. These findings demonstrate that thymidine can serve as a glycolytic pathway substrate in human cancer cells.
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Desaki R., Sawada G., Okumura H., Ikeda R., Tanabe K., Komatsu H., Mimori K., Mori M., Kita Y., Uchikado Y., Arigami T., Uenosono Y., Owaki T., Ishigami S., Natsugoe S.
Annals of Surgical Oncology 24 ( 2 ) 586 - 593 2017.2
Language：English Publishing type：Research paper (scientific journal) Publisher：Annals of Surgical Oncology
© 2015, Society of Surgical Oncology. Background: Cysteine/histidine-rich 1 (CYHR1) was first discovered in a yeast two-hybrid screen with murine galectin-3, and no previous reports have described a relationship between the CYHR1 gene and human cancer. The current study evaluated the role and significance of CYHR1 in esophageal cancer. Methods: The human esophageal squamous cell carcinoma (ESCC) cell line TE-8 and the CYHR1 knock-down cell line TE-8/small interfering (si)-CYHR1 were used for in vitro and in vivo assays. For clinical study, ESCC tissues (n = 104) were used. Results: Compared with parental cells, TE-8/si-CYHR1 cells had suppressed proliferation and invasion activities. In the in vivo assay, the tumors from TE-8 cells treated with si-CYHR1 had abrogated tumorigenicity. In the clinical study, the expression of CYHR1 mRNA was associated with lymph node metastasis and stage and shown to be an independent prognostic factor. Conclusions: As the findings show, CYHR1 may represent not only a valuable prognostic marker but also a therapeutic target for ESCC patients.
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Incretin as a novel treatment strategy for NAFLD/NASH
Takeda Y., Ikeda R., Kondo T.
Yakugaku Zasshi 136 ( 4 ) 573 - 577 2016.4
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Yakugaku Zasshi
© 2016 The Pharmaceutical Society of Japan. Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) have been recognized as metabolic disorders characterized by fatty accumulation in the liver without alcohol consumption. The diseases can cause metabolic syndromes, consisting of obesity, diabetes mellitus (DM), dyslipidemia and hypertension. For the treatment of NAFLD/NASH, losing weight by exercise or diet remains the standard treatment, because no effective pharmacological therapy has yet been developed for NAFLD/NASH. Two incretin hormones, glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), stimulate glucose-mediated insulin production in pancreatic β cells. Incretin has also been reported to have various extra-pancreatic effects, including the regulation of hepatic glucose production, appetite and satiety, as well as the stimulation of aferent sensory nerves. Therefore, incretin may have potential as a novel therapeutic agent for NAFLD/NASH.
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Minami K., Shinsato Y., Yamamoto M., Takahashi H., Zhang S., Nishizawa Y., Tabata S., Ikeda R., Kawahara K., Tsujikawa K., Chijiiwa K., Yamada K., Akiyama S., Pérez-Torras S., Pastor-Anglada M., Furukawa T., Yasuo T.
Journal of Pharmacological Sciences 127 ( 3 ) 319 - 325 2015.1
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of Pharmacological Sciences
© 2015 Japanese Pharmacological Society. Production and hosting by Elsevier B.V. Gemcitabine is widely used for pancreatic, lung, and bladder cancer. However, drug resistance against gemcitabine is a large obstacle to effective chemotherapy. Nucleoside transporters, nucleoside and nucleotide metabolic enzymes, and efflux transporters have been reported to be involved in gemcitabine resistance. Although most of the resistant factors are supposed to be related to each other, it is unclear how one factor can affect the other one. In this study, we established gemcitabine-resistant pancreatic cancer cell lines. Gemcitabine resistance in these cells is caused by two major processes: a decrease in gemcitabine uptake and overexpression of ribonucleotide reductase large subunit (RRM1). Knockdown of RRM1, but not the overexpression of concentrative nucleoside transporter 1(CNT1), could completely overcome the gemcitabine resistance. RRM1 knockdown in gemcitabine-resistant cells could increase the intracellular accumulation of gemcitabine by increasing the nucleoside transporter expression. Furthermore, a synergistic effect was observed between hydroxyurea, a ribonucleotide reductase (RR) inhibitor, and gemcitabine on thegemcitabine-resistant cells.Hereweindicate that RRisoneofthe most promising targetstoovercome gemcitabine resistance in gemcitabine-resistant cells with dual resistant factors.
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Factors involved in the cisplatin resistance of KCP-4 human epidermoid carcinoma cells
Oiso S., Takayama Y., Nakazaki R., Matsunaga N., Motooka C., Yamamura A., Ikeda R., Nakamura K., Takeda Y., Kariyazono H.
Oncology Reports 31 ( 2 ) 719 - 726 2014.2
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Oncology Reports
KCP-4 is a cisplatin-resistant cell line established from human epidermoid carcinoma KB-3-1 cells. Although our previous study revealed that one of the mechanisms for cisplatin resistance in KCP-4 cells is the activation of NF-κB, its high resistance is considered to be induced by multiple mechanisms. In the present study, we explored other factors involved in the development of cisplatin resistance in KCP-4 cells. Since it has been reported that an unknown efflux pump exports cisplatin from KCP-4 cells in an ATP-dependent manner, we examined 48 types of ATP-binding cassette proteins as candidate cisplatin efflux transporters. The mRNA expression levels of ABCA1, ABCA3, ABCA7 and ABCB10 in KCP-4 cells were higher when compared to those in KB-3-1 cells. These expression levels in cisplatin-sensitive revertant KCP-4 cells (KCP-4R cells), were reduced in parallel with the sensitivity of these cells to cisplatin and their intracellular accumulation of cisplatin. Next, we investigated the occurrence of mutations in p53 in KCP-4 cells. We found a heterozygous missense mutation at codon 72 (p.Pro72Arg) in p53 of both KCP-4 and KB-3-1 cells, but the protein expression level of p53 in KCP-4 cells was higher when compared to that in KB-3-1. These results suggest that ABCA1, ABCA3, ABCA7 and ABCB10 are candidate genes for the cisplatin efflux transporter that is involved in the cisplatin resistance of KCP-4 cells, and that the mutation at codon 72 of p53 may contribute to the development of cisplatin resistance.
DOI： 10.3892/or.2013.2896
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Sonoda J., Ikeda R., Baba Y., Narumi K., Kawachi A., Tomishige E., Nishihara K., Takeda Y., Yamada K., Sato K., Motoya T.
Experimental and Therapeutic Medicine 8 ( 1 ) 59 - 63 2014.1
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Experimental and Therapeutic Medicine
Clinical and epidemiological studies have indicated that the consumption of green tea has a number of beneficial effects on health. Epigallocatechin-3-gallate (EGCg), the major polyphenolic compound present in green tea, has received much attention as an active ingredient. Among the numerous promising profiles of EGCg, the present study focused on the anticancer effects. Apoptosis induced by EGCg and subsequent cell growth suppression have been demonstrated in a number of cell culture studies. However, the underlying mechanism of apoptotic cell death remains unclear. Thus, the aim of the present study was to identify the major molecule that mediates proapoptotic cell death by EGCg. The effect of EGCg on cell proliferation and the induction of mRNA that modulates apoptotic cell death was evaluated in the A549 human non-small-cell lung cancer cell line. In addition, morphological changes were assessed by microscopy in A549 cells that had been treated with 100 μM EGCg for 24 h. The MTT assay revealed that cell proliferation was significantly reduced by EGCg in a dose-dependent manner (3-100 μM). The mRNA expression level of B-cell lymphoma-extra large (Bcl-xL) was decreased in A549 cells following 24 h incubation with 100 μM EGCg. Therefore, the results indicated that the inhibition of cell proliferation by EGCg may be achieved via suppressing the expression of the cell death-inhibiting gene, Bcl-xL.
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Ikeda R., Nishizawa Y., Tajitsu Y., Minami K., Mataki H., Masuda S., Furukawa T., Akiyama S., Yamada K., Takeda Y.
Oncology Reports 31 ( 1 ) 197 - 201 2014.1
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Oncology Reports
Major vault protein (MVP) is the main constituent of the vault ribonucleoprotein particle and is identical to lung resistance-related protein (LRP). Although MVP is also expressed in several types of normal tissues, little is known about its physiological role. In the present study, we identified the crucial MVP promoter elements that regulate MVP expression. An examination of tissue expression profiles revealed that MVP was expressed in the heart, placenta, lung, liver, kidney and pancreas. Elements of the MVP promoter contain binding sites for transcription factors, STAT, p53, Sp1, E-box, GATA, MyoD and Y-box. By deletion analysis, a conserved proximal E-box binding site was demonstrated to be important for human MVP promoter transactivation. Introduction of siRNA against upstream stimulating factor (USF) 1, which is known to bind the E-box binding site, decreased the expression of MVP in SW620 and ACHN cells. Using a chromatin immunoprecipitation (ChIP) assay, USF1 bound the MVP promoter in SW620 cells. These findings suggest that USF1 binding to an E-box element may be critical for basal MVP promoter activation. The results of the present study are useful in understanding the molecular mechanisms regulating MVP gene expression, and may aid in elucidating the physiological functions of MVP.
DOI： 10.3892/or.2013.2818
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Tabata S., Ikeda R., Yamamoto M., Shimaoka S., Mukaida N., Takeda Y., Yamada K., Soga T., Furukawa T., Akiyama S.
Oncotarget 5 ( 21 ) 10473 - 10485 2014.1
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Oncotarget
Thymidine phosphorylase (TP) promotes angiogenesis and metastasis, and confers resistance to anticancer agents in some cancer cell types. We previously reported that TP stimulates the expression of interleukin (IL)-8 in human KB cancer cells by an unknown mechanism. A mutation in the nuclear factor (NF)κB binding site of the IL-8 promoter suppressed promoter activity in KB/TP cells that overexpress TP. Specifically inhibiting NFκB by using BY11-7082 also suppressed TP-induced IL-8 promoter activity and IL-8 expression. Moreover, TP overexpression led to the activation of NFκB and an upregulation in the expression of its target genes, and increased phosphorylated IKKa/β protein levels, while promoting IκBa degradation as well as p65 phosphorylation and nuclear localization. The activation of NFκB in KB/TP cells was suppressed by the antioxidants N-acetylcysteine and EUK-8. In addition, in gastric cancer tissue samples, the expression of the NFκB-regulated genes, including IL-8, IL-6, and fibronectin-1 was positively correlated with TP expression. These findings indicate that reactive oxygen species mediated NFκB activation by TP increases the expression of genes that promote angiogenesis and metastasis in gastric cancer.
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Tamai M., Matsushita S., Miyanohara H., Imuta N., Ikeda R., Kawai K., Nishi J., Sakamoto A., Shigihara T., Kanekura T.
Journal of Dermatology 40 ( 12 ) 1020 - 1026 2013.12
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of Dermatology
Methicillin-resistant Staphylococcus aureus (MRSA) has rapidly emerged as a cause of severe and intractable skin infection. At present, there are no effective topical treatments, and infection or colonization by MRSA of the skin raises serious medical problems. We developed an ultrasonic levitation washer that generates silver ions (Ag+) and ozone (O3) to clean and sterilize medical devices. We report the effect of ultrasonic levitation (levitation) with Ag+ and O3 on MRSA in vitro and in vivo. Antimicrobial effect against six MRSA strains of all agr types was examined under three in vitro conditions; cells floating in a water tank, cells infiltrating-, and cells forming a biofilm on an atelocollagen membrane. In the in vivo studies, we assayed the number of MRSA organisms that survived treatment on murine skin ulcers and evaluated the ulcer size. Levitation with Ag + dramatically decreased the survival of MRSA floating in a water tank. Levitation with Ag+ and O3 significantly decreased the viability of MRSA that had infiltrated or formed a biofilm on atelocollagen membranes regardless of the level of biofilm production. In vivo studies showed that the number of MRSA on murine skin ulcers was significantly decreased when 15-min treatment was performed for 7 consecutive days and that the ulcer size was significantly decreased after the seventh treatment course. Levitation with Ag+ and O3 may be a valuable tool for treating MRSA infestation of the skin and for accelerating wound healing. © 2013 Japanese Dermatological Association.
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Tajitsu Y., Ikeda R., Nishizawa Y., Mataki H., Che X., Sumizawa T., Nitta M., Yamaguchi T., Yamamoto M., Tabata S., Akiyama S., Yamada K., Furukawa T., Takeda Y.
International Journal of Molecular Medicine 32 ( 3 ) 703 - 708 2013.9
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：International Journal of Molecular Medicine
Major vault protein (MVP) is identical to lung resistance-related protein (LRP), which is the major component of vaults. Vaults are considered to play a protective role against xenobiotics and other types of stress. In a previous study, we reported that the expression levels of MVP in SW620 human colon cancer cells were increased in hypertonic culture medium with sucrose. However, the molecular mechanism behind the induction of MVP expression by osmotic stress has not yet been elucidated. Therefore, in the present study, we investigated the mechanism behind the induction of MVP expression by osmotic stress. Under hyperosmotic stress conditions, the ubiquitination of specificity protein 1 (Sp1) decreased, Sp1 protein levels increased, its binding to the MVP promoter was enhanced, and small interfering RNA (siRNA) for Sp1 suppressed the induction of MVP expression. The inhibition of c-jun N-terminal kinase (JNK) by SP600125, a specific JNK inhibitor, decreased the expression of MVP and Sp1 under hyperosmotic conditions. Our data indicate that the stabilization and upregulation of Sp1 protein expression by JNK participate in the inhibition of the ubiquitination and degradation of Sp1, and thus in the induction of MVP expression under hyperosmotic conditions.
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Molecular basis for the regulation of hypoxia-inducible factor-1α levels by 2-deoxy-D-ribose
Ikeda R., Tabata S., Tajitsu Y., Nishizawa Y., Minami K., Furukawa T., Yamamoto M., Shinsato Y., Akiyama S., Yamada K., Takeda Y.
Oncology Reports 30 ( 3 ) 1444 - 1448 2013.9
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Oncology Reports
The angiogenic factor, platelet-derived endothelial cell growth factor/thymidine phosphorylase (PD-ECGF/TP), stimulates the chemotaxis of endothelial cells and confers resistance to apoptosis induced by hypoxia. 2-Deoxy-D-ribose, a degradation product of thymidine generated by TP enzymatic activity, inhibits the upregulation of hypoxia-inducible factor (HIF) 1α, BNIP3 and caspase-3 induced by hypoxia. In the present study, we investigated the molecular basis for the suppressive effect of 2-deoxy-D-ribose on the upregulation of HIF-1α. 2-Deoxy-D-ribose enhanced the interaction of HIF-1α and the von Hippel-Lindau (VHL) protein under hypoxic conditions. It did not affect the expression of HIF-1α, prolyl hydroxylase (PHD)1/2/3 and VHL mRNA under normoxic or hypoxic conditions, but enhanced the interaction of HIF-1α and PHD2 under hypoxic conditions. 2-Deoxy-D-ribose also increased the amount of hydroxy-HIF-1α in the presence of the proteasome inhibitor MG-132. The expression levels of TP are elevated in many types of malignant solid tumors and, thus, 2-deoxy-D-ribose generated by TP in these tumors may play an important role in tumor progression by preventing hypoxia-induced apoptosis.
DOI： 10.3892/or.2013.2572
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VEGF expression is augmented by hypoxia-induced PGIS in human fibroblasts
Wang J., Ikeda R., Che X., Ooyama A., Yamamoto M., Furukawa T., Hasui K., Zheng C., Tajitsu Y., Oka T., Tabata S., Nishizawa Y., Eizuru Y., Akiyama S.
International Journal of Oncology 43 ( 3 ) 746 - 754 2013.9
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：International Journal of Oncology
Prostacyclin synthase (PGIS or PTGIS) is an enzyme that catalyses the conversion of prostaglandin H2(PGH2) to prostaglandin I2(PGI2). PGI2promotes cancer growth by activating peroxisome proliferator-activated receptor δ (PPARδ), and increases the expression levels of the pro-angiogenic factor vascular endothelial growth factor (VEGF). We found that the expression of the PGIS gene was enhanced in WI-38, TIG-3-20 and HEL human lung fibroblast cells and two cancer cell lines (NB-1 and G361) under hypoxic conditions. The main localization of PGIS changed from the cytoplasm to the nucleus by hypoxia in WI-38 cells. The induced PGIS had an enzymatic activity since the intracellular level of 6-keto-prostaglandin, a useful marker of PGI2biosynthesis in vivo, was increased with the increasing levels of PGIS. Expression of VEGF was increased in parallel with PGIS induction under hypoxic conditions. PGIS knockdown resulted in the decreased expression of VEGF mRNA. Since VEGF is a known PPARδ target gene, we examined the effects of siRNAs targeting PPARδ on the expression of VEGF under hypoxic conditions. Knockdown of PPARδ suppressed the expression of VEGF under hypoxic conditions in WI-38 cells. These findings suggest that PGIS is induced by hypoxia and regulates the expression of VEGF in fibroblasts. Fibroblasts in the hypoxic area of tumors may have an important role in tumor growth and angiogenesis.
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Autocrine effects of neuromedin b stimulate the proliferation of rat primary osteoblasts
Saito H., Nakamachil T., Inoue K., Ikeda R., Kitamura K., Minamino N., Shioda S., Miyata A.
Journal of Endocrinology 217 ( 2 ) 141 - 150 2013.5
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of Endocrinology
Neuromedin B (NMB) is a mammalian bombesin-like peptide that regulates exocrine/ endocrine secretion, smooth muscle contraction, body temperature, and the proliferation of some cell types. Here, we show that mRNA encoding Nmb and its receptor (Nmbr) are expressed in rat bone tissue. Immunohistochemical analysis demonstrated thatNMB andNMBR colocalize in osteoblasts, epiphyseal chondrocytes, and proliferative chondrocytes of growth plates frommouse hind limbs. Then, we investigated the effect of NMB on the proliferation of rat primary cultured osteoblasts. Proliferation assays and 5-bromo-2′-deoxyuridine incorporation assays demonstrated that NMB augments the cell number and enhances DNA synthesis in osteoblasts. Pretreatment with the NMBR antagonist BIM23127 inhibited NMB-induced cell proliferation and DNA synthesis. Western blot analysis showed that NMB activates ERK1/2 MAPK signaling in osteoblasts. Pretreatment with the MAPK/ERK kinase inhibitor U0126 attenuatedNMB-induced cell proliferation and DNA synthesis.We also investigated the effects ofmolecules that contribute to osteoblast proliferation and differentiation onNmb expression in osteoblasts. Real-time PCR analysis demonstrated that 17b-estradiol (E2) and transforming growth factor b1 increase and decrease Nmb mRNA expression levels respectively. Finally, proliferation assays revealed that the NMBR antagonist BIM23127 suppresses E2-induced osteoblast proliferation. These results suggest that NMB/NMBR signaling plays an autocrine or paracrine role in osteoblast proliferation and contributes to the regulation of bone formation. © 2013 Society for Endocrinology.
DOI： 10.1530/JOE-12-0488
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Shinsato Y., Furukawa T., Yunoue S., Yonezawa H., Minami K., Nishizawa Y., Ikeda R., Kawahara K., Yamamoto M., Hirano H., Tokimura H., Arita K.
Oncotarget 4 ( 12 ) 2261 - 2270 2013.1
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Oncotarget
Although there is a relationship between DNA repair deficiency and temozolomide (TMZ) resistance in glioblastoma (GBM), it remains unclear which molecule is associated with GBM recurrence. We isolated three TMZ-resistant human GBM cell lines and examined the expression of O6-methylguanine-DNA methyltransferase (MGMT) and mismatch repair (MMR) components. We used immunohistochemical analysis to compare MutL homolog 1 (MLH1), postmeiotic segregation increased 2 (PMS2) and MGMT expression in primary and recurrent GBM specimens obtained from GBM patients during TMZ treatment. We found a reduction in MLH1 expression and a subsequent reduction in PMS2 protein levels in TMZ-resistant cells. Furthermore, MLH1 or PMS2 knockdown confered TMZ resistance. In recurrent GBM tumours, the expression of MLH1 and PMS2 was reduced when compared to primary tumours.
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Matsushita S., Ikeda R., Fukushige T., Tajitsu Y., Gunshin K., Okumura H., Ushiyama M., Akiyama S., Kawai K., Takeda Y., Yamada K., Kanekura T.
Journal of Dermatological Science 68 ( 1 ) 19 - 24 2012.10
Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Journal of Dermatological Science
Background The treatment of melanoma, an aggressive, chemo-resistant skin cancer characterized by rapid metastasis and a poor prognosis, requires the development of innovative therapies with improved efficacy. The p53R2 gene that encodes the ribonucleotide reductase small subunit 2 homologue is induced by several stress signals including DNA-damaging agents that activate p53. The p53R2 gene product increases the deoxynucleotide triphosphate pool in the nucleus; this facilitates DNA repair and synthesis.Objective We examined the expression of p53R2 in melanoma and evaluated whether p53R2 is involved in the growth and proliferation of melanoma cells.Methods We examined the clinicopathological significance of p53R2 in melanoma. To investigate the role of p53R2 in melanoma we used KHm5 and KHm6 melanoma cells that express p53R2, and p53R2-targeting small interfering (si) RNA.Results p53R2 expression was detected immunohistochemically in 56 of 78 patients (71.8%). The expression of p53R2 was significantly correlated with the depth of invasion and the tumor stage. p53R2-targeting siRNA successfully knocked down p53R2 and significantly inhibited the growth of KHm5 and 6 cells. Moreover, The degree of KHm5 and 6 cell growth inhibition was greater in the presence of both p53R2-targeting siRNA and nimustine (ACNU) than with ACNU alone, suggesting that p53R2 silencing enhanced the chemosensitivity of KHm5 and 6 cells to ACNU.Conclusions We propose p53R2 as a therapeutic target to enhance the effectiveness of chemotherapy in patients with p53R2-positive melanoma. © 2012 Japanese Society for Investigative Dermatology.