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Articles by T Tanaka
Total Records ( 16 ) for T Tanaka
  T Ishii Yonemoto , H Masuzaki , S Yasue , S Okada , C Kozuka , T Tanaka , M Noguchi , T Tomita , J Fujikura , Y Yamamoto , K Ebihara , K Hosoda and K. Nakao

Increased expression and activity of the intracellular glucocorticoid-reactivating enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) contribute to dysfunction of adipose tissue. Although the pathophysiological role of 11β-HSD1 in mature adipocytes has long been investigated, its potential role in preadipocytes still remains obscure. The present study demonstrates that the expression of 11β-HSD1 in preadipocyte-rich stromal vascular fraction (SVF) cells in fat depots from ob/ob and diet-induced obese mice was markedly elevated compared with lean control. In 3T3-L1 preadipocytes, the level of mRNA and reductase activity of 11β-HSD1 was augmented by TNF-, IL-1β, and LPS, with a concomitant increase in inducible nitric oxide synthase (iNOS), monocyte chemoattractant protein-1 (MCP-1), or IL-6 secretion. Pharmacological inhibition of 11β-HSD1 and RNA interference against 11β-HSD1 reduced the mRNA and protein levels of iNOS, MCP-1, and IL-6. In contrast, overexpression of 11β-HSD1 further augmented TNF--induced iNOS, IL-6, and MCP-1 expression. Moreover, 11β-HSD1 inhibitors attenuated TNF--induced phosphorylation of NF-B p65 and p38-, JNK-, and ERK1/2-MAPK. Collectively, the present study provides novel evidence that inflammatory stimuli-induced 11β-HSD1 in activated preadipocytes intensifies NF-B and MAPK signaling pathways and results in further induction of proinflammatory molecules. Not limited to 3T3-L1 preadipocytes, we also demonstrated that the notion was reproducible in the primary SVF cells from obese mice. These findings highlight an unexpected, proinflammatory role of reamplified glucocorticoids within preadipocytes in obese adipose tissue.

  T Shimizu , T Tanaka , T Iso , H Doi , H Sato , K Kawai Kowase , M Arai and M. Kurabayashi

Objective— Vascular calcification is closely correlated with cardiovascular morbidity and mortality. Here, we demonstrate the role of Notch signaling in osteogenic differentiation and mineralization of vascular smooth muscle cells (SMCs).

Methods and Results— The Msx2 gene, a key regulator of osteogenesis, was highly induced by coculture with Notch ligand-expressing cells or overexpression of Notch intracellular domains (NICDs) in human aortic SMCs (HASMCs). Furthermore, the Notch1 intracellular domain (N1-ICD) overexpression markedly upregulated alkaline phosphatase (ALP) activity and matrix mineralization of HASMCs. A knockdown experiment with a small interfering RNA confirmed that Msx2 mediated N1-ICD–induced osteogenic conversion of HASMCs. Interestingly, Msx2 induction by N1-ICD was independent of bone morphogenetic protein–2 (BMP-2), an osteogenic morphogen upstream of Msx2. The transcriptional activity of the Msx2 promoter was significantly enhanced by N1-ICD overexpression. The RBP-Jk binding element within the Msx2 promoter was critical to Notch-induced Msx2 gene expression. Correspondingly, N1-ICD overexpression did not induce the Msx2 expression in RBP-Jk–deficient fibroblasts. Immunohistochemistry of human carotid artery specimens revealed localization of Notch1, Jagged1 and Msx2 to fibrocalcific atherosclerotic plaques.

Conclusion— These results imply a new mechanism for osteogenic differentiation of vascular SMCs in which Notch/RBP-Jk signaling directly induces Msx2 gene expression and suggest its crucial role in mediating vascular calcification.

  T Toyoda , T Tsukamoto , S Takasu , N Hirano , H Ban , L Shi , T Kumagai , T Tanaka and M. Tatematsu

Statins are commonly used lipid-lowering drugs that reduce the risk of cardiovascular morbidity and mortality. Although recent studies have pointed to chemopreventive effects of statins against various cancers, their efficacy for gastric cancer is unclear. Here, we examined the effects of pitavastatin, a lipophilic statin, on Helicobacter pylori (H. pylori)–associated stomach carcinogenesis and gastritis using Mongolian gerbil and mouse models. The animals were allocated to H. pylori + N-methyl-N-nitrosourea administration (gerbils, 52 weeks) or H. pylori infection alone groups (gerbils and mice, 12 weeks). After H. pylori infection, they were fed basal diets containing 0 to 10 ppm of pitavastatin. The incidences of H. pylori–associated gastric adenocarcinomas and degrees of chronic gastritis were not decreased by pitavastatin compared with those of control values. Expression of interleukin-1β and tumor necrosis factor- mRNAs in the pyloric mucosa was markedly up-regulated in pitavastatin-treated animals. Furthermore, in the H. pylori–infected groups, serum total cholesterol, triglyceride, and low-density lipoprotein levels were significantly increased by pitavastatin treatment, contrary to expectation. In the short-term study, H. pylori–infected gerbils and mice also showed significant up-regulation of serum triglyceride levels by pitavastatin, whereas total cholesterol was markedly reduced and low-density lipoprotein exhibited a tendency for decrease in noninfected animals. These findings indicate pitavastatin to be ineffective for suppressing gastritis and chemoprevention of gastric carcinogenesis in H. pylori–infected gerbils. Our serologic results also suggest that the H. pylori infection and consequent severe chronic gastritis interfere with the cholesterol-lowering effects of pitavastatin.

  A Appert , C. H Nam , N Lobato , E Priego , R. N Miguel , T Blundell , L Drynan , H Sewell , T Tanaka and T. Rabbitts

LMO2 is a transcription regulator involved in human T-cell leukemia, including some occurring in X-SCID gene therapy trials, and in B-cell lymphomas and prostate cancer. LMO2 functions in transcription complexes via protein-protein interactions involving two LIM domains and causes a preleukemic T-cell development blockade followed by clonal tumors. Therefore, LMO2 is necessary but not sufficient for overt neoplasias, which must undergo additional mutations before frank malignancy. An open question is the importance of LMO2 in tumor development as opposed to sustaining cancer. We have addressed this using a peptide aptamer that binds to the second LIM domain of the LMO2 protein and disrupts its function. This specificity is mediated by a conserved Cys-Cys motif, which is similar to the zinc-binding LIM domains. The peptide inhibits Lmo2 function in a mouse T-cell tumor transplantation assay by preventing Lmo2-dependent T-cell neoplasia. Lmo2 is, therefore, required for sustained T-cell tumor growth, in addition to its preleukemic effect. Interference with LMO2 complexes is a strategy for controlling LMO2-mediated cancers, and the finger structure of LMO2 is an explicit focus for drug development. [Cancer Res 2009;69(11):4784–90]

  T Tanaka and L. M. De Luca

Retinoid X receptor (RXR) is a combinatorial partner for one third of the 48 human nuclear receptor superfamily members and acts as a master coordinator of nuclear receptor signaling pathways involved in the control of cell growth and differentiation. Thus, ligand-dependent simultaneous activation of multiple pathways is an attractive strategy for molecular-targeted therapy of neoplastic disease. However, clinical trials in RXR-targeted molecular therapy with the RXR ligand (rexinoid) have yielded disappointing outcomes. In this review, we discuss a possible mechanism underlying the loss of sensitivity to rexinoid therapy. [Cancer Res 2009;69(12):4945–-47]

  M Yasuda , T Nishizawa , H Ohigashi , T Tanaka , D. X Hou , N. H Colburn and A. Murakami

(±)-13-Hydroxy-10-oxo-trans-11-octadecenoic acid (13-HOA) is one of the lipoxygenase metabolites of linoleic acid (LA) from corn germ. Recently, we reported that this metabolite suppressed the expression of lipopolysaccharide-induced proinflammatory genes in murine macrophages by disrupting mitogen-activated protein kinases and Akt pathways. In this study, we investigated the inhibitory effects of 13-HOA on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation in ears and skin, as well as tumor promotion in female ICR mice. Pretreatment with 13-HOA (1600 nmol) inhibited ear edema formation by 95% (P < 0.05) in an inflammation test and reduced tumor incidence and the number of tumors per mouse by 40 and 64% (P < 0.05 each), respectively, in a two-stage skin carcinogenesis model. Histological examinations revealed that it decreased epidermal thickness, the number of infiltrated leukocytes and cell proliferation index. Furthermore, 13-HOA (8–40 µM) suppressed TPA-induced anchorage-independent growth of JB6 mouse epidermal cells by 70–100%, whereas LA was virtually inactive. 13-HOA (40 µM) inhibited TPA-induced activator protein-1 transactivation but not extracellular signal-regulated kinase1/2 activation. Interestingly, 13-HOA (40 µM and 1600 nmol in JB6 cells and mouse skin, respectively) induced expression of programmed cell death 4 (Pdcd4), a novel tumor suppressor protein. To our knowledge, this is the first report of a food factor that is able to induce Pdcd4 expression. Collectively, our results indicate that 13-HOA may be a novel anti-inflammatory and antitumor chemopreventive agent with a unique mode of action.

  K. V Tarasov , S Sanna , A Scuteri , J. B Strait , M Orru , A Parsa , P. I Lin , S Lai , M. G Piras , M Masala , T Tanaka , W Post , J. R O`Connell , D Schlessinger , A Cao , R Nagaraja , B. D Mitchell , G. R Abecasis , A. R Shuldiner , M Uda , E. G Lakatta and S. S. Najjar

Background— Pulse wave velocity (PWV), a noninvasive index of central arterial stiffness, is a potent predictor of cardiovascular mortality and morbidity. Heritability and linkage studies have pointed toward a genetic component affecting PWV. We conducted a genome-wide association study to identify single-nucleotide polymorphisms (SNPs) associated with PWV.

Methods and Results— The study cohort included participants from the SardiNIA study for whom PWV measures were available. Genotyping was performed in 4221 individuals, using either the Affymetrix 500K or the Affymetrix 10K mapping array sets (with imputation of the missing genotypes). Associations with PWV were evaluated using an additive genetic model that included age, age2, and sex as covariates. The findings were tested for replication in an independent internal Sardinian cohort of 1828 individuals, using a custom chip designed to include the top 43 nonredundant SNPs associated with PWV. Of the loci that were tested for association with PWV, the nonsynonymous SNP rs3742207 in the COL4A1 gene on chromosome 13 and SNP rs1495448 in the MAGI1 gene on chromosome 3 were successfully replicated (P=7.08x10–7 and P=1.06x10–5, respectively, for the combined analyses). The association between rs3742207 and PWV was also successfully replicated (P=0.02) in an independent population, the Old-Order Amish, leading to an overall P=5.16x10–8.

Conclusions— A genome-wide association study identified a SNP in the COL4A1 gene that was significantly associated with PWV in 2 populations. Collagen type 4 is the major structural component of basement membranes, suggesting that previously unrecognized cell-matrix interactions may exert an important role in regulating arterial stiffness.

  L. S Mangala , V Zuzel , R Schmandt , E. S Leshane , J. B Halder , G. N Armaiz Pena , W. A Spannuth , T Tanaka , M. M.K Shahzad , Y. G Lin , A. M Nick , C. G Danes , J. W Lee , N. B Jennings , P. E Vivas Mejia , J. K Wolf , R. L Coleman , Z. H Siddik , G Lopez Berestein , S Lutsenko and A. K. Sood

Purpose: Resistance to platinum chemotherapy remains a significant problem in ovarian carcinoma. Here, we examined the biological mechanisms and therapeutic potential of targeting a critical platinum resistance gene, ATP7B, using both in vitro and in vivo models.

Experimental Design: Expression of ATP7A and ATP7B was examined in ovarian cancer cell lines by real-time reverse transcription-PCR and Western blot analysis. ATP7A and ATP7B gene silencing was achieved with targeted small interfering RNA (siRNA) and its effects on cell viability and DNA adduct formation were examined. For in vivo therapy experiments, siRNA was incorporated into the neutral nanoliposome 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC).

Results: ATP7A and ATP7B genes were expressed at higher levels in platinum-resistant cells compared with sensitive cells; however, only differences in ATP7B reached statistical significance. ATP7A gene silencing had no significant effect on the sensitivity of resistant cells to cisplatin, but ATP7B silencing resulted in 2.5-fold reduction of cisplatin IC50 levels and increased DNA adduct formation in cisplatin-resistant cells (A2780-CP20 and RMG2). Cisplatin was found to bind to the NH2-terminal copper-binding domain of ATP7B, which might be a contributing factor to cisplatin resistance. For in vivo therapy experiments, ATP7B siRNA was incorporated into DOPC and was highly effective in reducing tumor growth in combination with cisplatin (70-88% reduction in both models compared with controls). This reduction in tumor growth was accompanied by reduced proliferation, increased tumor cell apoptosis, and reduced angiogenesis.

Conclusion: These data provide a new understanding of cisplatin resistance in cancer cells and may have implications for therapeutic reversal of drug resistance.

  H Matsushita , A Ishihara , S Mashiko , T Tanaka , T Kanno , H Iwaasa , H Ohta and A. Kanatani

Nociceptin/orphanin FQ (N/OFQ), an endogenous ligand for opioid receptor-like 1 (ORL1), is involved in various central functions, such as pain, psychological stress, locomotor activity, learning and memory, and feeding regulation. Of these functions, the role of N/OFQ in the regulation of feeding has been suggested by the fact that the central administration of N/OFQ leads to feeding behavior. However, the manner in which N/OFQ influences body weight control and subsequent obesity is unclear. To clarify the involvement of N/OFQ in the development of obesity, we evaluated the effects of intracerebroventricular infusion of N/OFQ on food intake and body weight in C57BL/6J mice that were fed a regular chow diet or moderately high-fat (MHF) diet (32.6% kcal fat). N/OFQ significantly increased food intake and body weight both in the regular diet- and MHF diet-fed mice, and these changes were more apparent in the MHF diet-fed mice. When we performed a pair-feeding study in N/OFQ intracerebroventricularly infused mice, N/OFQ did not cause body weight gain but increased white adipose tissue weight and plasma leptin, insulin, and cholesterol levels. N/OFQ reduced rectal temperature in pair-fed mice, in keeping with decreased UCP1 mRNA expression in brown adipose tissue. These results suggest that N/OFQ contributes to the development of obesity not only by inducing hyperphagia but also by decreasing energy expenditure.

  T Tanaka , H Kitamura , A Takahashi , N Masumori and T. Tsukamoto

We retrospectively assessed long-term outcomes of chemotherapy for advanced germ cell tumors (GCTs) at our institution.


Ninety-five consecutive males with advanced GCTs of the testis or extragonadal origin who received chemotherapy between 1980 and 2006 were enrolled. All patients underwent induction chemotherapy including cisplatin.


The median follow-up period was 36.1 months (0 – 288.5) for all patients and 52.6 months (2.2 – 288.5) for the 73 current survivors. Totally, 75 patients (78.9%) achieved complete remission (CR). CR was achieved in 61.1%, 37.9% and 75.0% of the patients after induction therapy, second-line therapy and third-line or more, respectively. As salvage therapy, high-dose chemotherapy was performed in 11 patients (11.7%) and regimens with novel anticancer agents such as paclitaxel and irinotecan were employed for 8 patients (8.5%) from 2003 and later. The era of the treatment, extrapulmonary metastasis and serum -fetoprotein were independent prognostic factors for patients. The 5-year overall survival of patients after 1992 was 83.0%, which was significantly higher than that of those before 1992 (56.3%). CR was never achieved in 20 patients and most of them met the criteria of the poor-prognosis group. Disease recurrence after CR was found in nine patients who were initially classified into the good- or intermediate-prognosis group.


Improvement of medical management during chemotherapy and the development of several regimens for salvage chemotherapy seemed to contribute to improving outcomes of patients with advanced testicular cancer. Newly established chemotherapy regimens are needed for improvement of survival of patients in the poor-prognosis group.

  S Iwasa , C Morizane , T Okusaka , H Ueno , M Ikeda , S Kondo , T Tanaka , K Nakachi , S Mitsunaga , Y Kojima , A Hagihara and N. Hiraoka

The combination chemotherapy consisting of cisplatin and etoposide, one of the standard regimens for small cell lung cancer, has been widely used to treat extrapulmonary poorly differentiated neuroendocrine carcinomas. However, there were no prior reports limited to the hepatobiliary tract and pancreas as the primary sites.


We reviewed the cases in our database from October 1995 to January 2009 and retrospectively examined the clinical data of patients, with unresectable or recurrent poorly differentiated neuroendocrine carcinoma arising from the hepatobiliary tract and pancreas, who received combination chemotherapy with cisplatin and etoposide as the first-line treatment. The chemotherapy regimen consisted of cisplatin 80 mg/m2 given intravenously on day 1 and etoposide 100 mg/m2 intravenously on days 1–3, repeated every 3–4 weeks.


Twenty-one patients were treated with the above regimen of cisplatin and etoposide combination chemotherapy. The primary tumor site was the liver in 2 patients, gallbladder in 8 patients, pancreas in 10 patients and ampulla of Vater in 1 patient. Although no complete responses were obtained, three patients had partial responses, resulting in an overall response rate of 14%. Median progression-free survival was 1.8 months, and median overall survival was 5.8 months. The major adverse events were myelosuppression and gastrointestinal toxicities, with Grade 3 or 4 neutropenia (90%), nausea (33%) and anorexia (24%).


Cisplatin and etoposide combination as the first-line chemotherapy for hepatobiliary or pancreatic poorly differentiated neuroendocrine carcinoma had only marginal antitumor activity and relatively severe toxicity compared with previous studies on extrapulmonary poorly differentiated neuroendocrine carcinoma treated with the same regimen.

  A Oguri , T Tanaka , H Iida , K Meguro , H Takano , H Oonuma , S Nishimura , T Morita , T Yamasoba , R Nagai and T. Nakajima

Voltage-gated Ca2+ channels (CaV) are ubiquitously expressed in various cell types and play vital roles in regulation of cellular functions including proliferation. However, the molecular identities and function of CaV remained unexplored in preadipocytes. Therefore, whole cell voltage-clamp technique, conventional/quantitative real-time RT-PCR, Western blot, small interfering RNA (siRNA) experiments, and immunohistochemical analysis were applied in mouse primary cultured preadipocytes as well as mouse 3T3-L1 preadipocytes. The effects of CaV blockers on cell proliferation and cell cycle were also investigated. Whole cell recordings of 3T3-L1 preadipocytes showed low-threshold CaV, which could be inhibited by mibefradil, Ni2+ (IC50 of 200 µM), and NNC55-0396. Dominant expression of 1G mRNA was detected among CaV transcripts (1A1I), supported by expression of CaV3.1 protein encoded by 1G gene, with immunohistochemical studies and Western blot analysis. siRNA targeted for 1G markedly inhibited CaV. Dominant expression of 1G mRNA and expression of CaV3.1 protein were also observed in mouse primary cultured preadipocytes. Expression level of 1G mRNA and CaV3.1 protein significantly decreased in differentiated adipocytes. Mibefradil, NNC55-0396, a selective T-type CaV blocker, but not diltiazem, inhibited cell proliferation in response to serum. NNC55-0396 and siRNA targeted for 1G also prevented cell cycle entry/progression. The present study demonstrates that the CaV3.1 T-type Ca2+ channel encoded by 1G subtype is the dominant CaV in mouse preadipocytes and may play a role in regulating preadipocyte proliferation, a key step in adipose tissue development.

  J Ishii , K Izawa , S Matsumura , K Wakamura , T Tanino , T Tanaka , C Ogino , H Fukuda and A. Kondo

To allow the comprehensive assessments of yeast expression systems, a simple and immediate method for simultaneously evaluating the expression level and plasmid maintenance in yeast was demonstrated. This method uses green fluorescent protein (GFP) and flow cytometry (FCM) and is characterized by a dual analysis of the average intensity of GFP fluorescence and the population of GFP-expressing cells. The FCM analysis of GFP fluorescence intensity rapidly quantifies the expression level without complex manipulations, such as the enzymatic reaction of a lacZ reporter assay. Moreover, the single-cell analysis revealed that the proportion of cells expressing GFP in the cell cluster reflects the plasmid retention rate; therefore, the FCM analysis of the GFP-expressing population allows the immediate estimation of the plasmid retention rate without the 2- or 3-day incubation required for colony counting. We show that the FCM analysis with GFP reporter is a suitable method to explore the hopeful expression vector and host strain or establish the several expression systems exhibiting the characteristic properties in yeast.

  T Shishido , Y Azumi , T Nakanishi , M Umetsu , T Tanaka , C Ogino , H Fukuda and A. Kondo

Bionanocapsule (BNC) is hollow nanoparticle composed of the l-protein of the hepatitis B virus surface antigen. BNC allows targeted delivery of either genes or drugs only to hepatocytes, but not to other cell types. In this study, we attempted to alter the specificity of BNC by insertion of biotin-acceptor peptide (BAP), which is efficiently biotinylated using biotin ligase BirA from Escherichia coli. Using streptavidin as a linker, biotinylated BNC could be display various biotinylated ligands that are otherwise difficult to fuse with BNC, such as antibodies, synthetic peptides and functional molecules. BAP-fused BNC was efficiently biotinylated and effectively displayed streptavidin. Furthermore, we demonstrated that biotinylated BNC was internalized into targeted cells via biotinylated Nanobody displayed on the BNC surface. Biotinylated BNC permit display of diverse ligands, and thus have potential as a versatile carrier for drug delivery to a variety of target cells.

  M Kubota , T Tanaka , T Kohno and K. Wakamatsu

Although detergents have been widely used in G-protein studies to increase solubility and stability of the protein, we noticed that detergents modulate the nucleotide-binding properties of G-proteins. Hence, we analysed the effects of detergents on guanine nucleotide exchange reactions of Gi1. Lubrol PX, a non-ionic detergent, which has been widely used in nucleotide dissociation/binding assays, was found to accelerate both GDP dissociation and GTPS binding from/to G in parallel at above its critical micelle concentration (cmc). Sodium cholate, an anionic detergent, which have been used to extract G-proteins from animal tissues, decelerated and accelerated GDP dissociation below and above its cmc, respectively. Surprisingly, micellar cholate decelerated GTPS binding, and the binding rate constant was decreased by three orders of magnitude in the presence of 2% cholate. These results demonstrate that the guanine nucleotide exchange reactions of Gi1 are drastically modulated by detergents differently depending on the type and the state (monomeric or micellar) of the detergents and that dissociation of GDP from Gi1 does not necessarily lead to immediate binding of GTP to Gi1 in some cases. These effects of detergents on G-proteins must be taken into account in G-protein experiments.

  Y Matsuura , M Ota , T Tanaka , M Takehira , K Ogasahara , B Bagautdinov , N Kunishima and K. Yutani

To enhance the heat stability of the CutA1 protein from Escherichia coli (EcCutA1) so that it has comparable stability to CutA1 from Pyrococcus horikoshii with a denaturation temperature (Td) of 150°C, we used the Stability Profile of Mutant Protein (SPMP) to examine the structure-sequence (3D-1D) compatibility between the conformation of EcCutA1 and its native sequence [J. Mol. Biol., 248, 733-738, (1995)]. We identified seven residues in EcCutA1 that were incompatible in terms of dihedral angles and hydrophobicity. These residues were replaced with appropriate amino acids, and the mutant proteins were evaluated for changes in stability by DSC and denaturant denaturation. The mutations that were introduced at five out of the seven positions improved the stability of EcCutA1. The Td values of single (S11A) and triple (S11V/E61V/Q73V) mutants improved by 16.5 and 26.6°C, respectively, compared to that of the wild-type protein (89.9°C). These analyses showed that (1) the stability of EcCutA1 is remarkably improved by slight substitutions, even though the stability of the wild-type protein is considerably high, (2) remarkable improvements in the stability can be quantitatively explained based on the newly solved native structure, and (3) SPMP is a powerful tool to examine substitutions that improve protein stability.

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