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Takashi Tsuruo

Publications and source records attributed to Takashi Tsuruo.

At least 37 records · Page 2Linked to original sources
PubMed2005

Identification of ATF-3, caveolin-1, DLC-1, and NM23-H2 as putative antitumorigenic, progesterone-regulated genes for ovarian cancer cells by gene profiling.

Although progesterone (P4) has been implicated to offer protection against ovarian cancer (OCa), little is known of its mechanism of action. The goal of this study was to identify P4-regulated genes that have anti-OCa action. Three immortalized nontumorigenic human ovarian surface epithelial (HOSE) cell lines and three OCa (OVCA) cell lines were subjected to 5 days of P4 treatment. Transcriptional profiling with a cDNA microarray containing approximately 2400 known genes was used to identify genes (1) whose expression was consistently downregulated in OVCA cell lines compared to HOSE cell lines, and (2) whose expression was restored in OCa cell lines by P4 treatment. From the candidates selected, activating transcription factor-3 (ATF-3), caveolin-1, deleted in liver cancer-1 (DLC-1), and nonmetastatic clone 23 (NM23-H2) were chosen for post hoc functional studies based on their previously reported action as tumor suppressors or apoptosis inducers. Semiquantitative RT-PCR analyses confirmed loss of or reduced transcription of these genes in OVCA cells when compared to HOSE cells and their upregulation following P4 treatment. Hormonal specificity was demonstrated by blockade experiments with a progestin antagonist RU 38486. Ectopic expression of caveolin-1, DLC-1, and NM23-H2 caused growth inhibition in OVCA cell cultures, but not in HOSE cell cultures, while forced expression of ATF-3 suppressed growth in both. Overexpression of AFT-3 also enhanced caspase-3 activity in both HOSE and OVCA cells, whereas ectopic expression of caveolin-1 and DLC-1 only activated this enzyme in OCa cells. In contrast, NM23-H2 overexpression was ineffective in activating caspase-3. Overexpression of any of the four genes in OCa cells reduced soft-agar colony formation and cell invasiveness. Taken together, we have identified four new P4-regulated, antitumor genes for OCa. However, their modes of action differ significantly; ATF-3 primarily functions as an apoptosis inducer, NM23-H2 as a suppressor of cell motility, and caveolin-1 and DLC-1 exhibiting features of classical tumor suppressors. To the best of our knowledge, except for NM23-H2, this is the first report linking P4 to the regulation of these tumor suppressor/proapoptotic genes, which could serve as future therapeutic targets.

Activating Transcription Factor 3↗
PubMed2005

Functional characterization of adenosine transport across the BBB in mice.

We investigated transport characteristics of adenosine across the blood-brain barrier (BBB) in mice. Uptake clearance across the BBB was measured by using an in situ mouse brain perfusion technique and cultured mouse brain capillary endothelial cell line (MBEC4 cells). Nucleoside transporter was cloned by RT-PCR and expressed on Xenopus laevis oocyte. Both in situ and in vitro studies revealed that the adenosine uptake is concentration-dependent, Na(+)-independent and S-(p-nitrobenzyl)-6-thioinosine (NBMPR)-sensitive. The K(t) values of in situ and in vitro studies were 31.7 +/- 13.8 microM and 11.9 +/- 2.84 microM, respectively. A good correlation was found for the inhibitory effects of nucleoside analogs to adenosine uptake between in situ and in vitro studies. RT-PCR revealed the expression of RNA of mouse equilibrative nucleoside transporter (mENT1) in mouse brain capillary and MBEC4 cells. In mENT1 expressed on X. laevis oocyte, K(t) value of adenosine transport was 6.9 +/- 2.7 microM (and comparable to those in situ and in vitro studies). In conclusion, we characterized the adenosine transport across the BBB in mice by using in situ brain perfusion technique and MBEC4 cells and found that these transports share common characteristics with mENT1-mediated transport. Transport of adenosine across the BBB in mice may be attributable to mENT1.

Adenosine↗
PubMed2005

Drug resistance in chemotherapy for breast cancer.

Recent developments with chemotherapy for breast cancer have improved patient survival. However, there continue to be nonresponders to conventional anticancer agents. Multidrug resistance (MDR) is caused by the expression of P-glycoprotein (P-gp) on the cell membrane. The expression of P-gp is encoded by MDR1 mRNA in tumors and is associated with clinical drug resistance. Since P-gp appears to be involved in both acquired and congenital MDR in human cancers, P-gp could be an important target for improving the efficacy of chemotherapy. Recently, we have focused on a therapeutic approach to reduce drug resistance in chemotherapy for breast cancer. Dofequidar fumarate (Dof) is a novel, orally active quinoline derivative that reverses multidrug resistance. In preclinical studies, the inhibition of doxorubicin-resistant cancer cell lines was observed in the presence of Dof + doxorubicin. We conducted clinical trials including Dof + cyclophosphamide (C), doxorubicin (A), and fluorouracil therapy (F) for patients with advanced or recurrent breast cancer. We compared the efficacy and tolerability of Dof + CAF with CAF alone. In this randomized, placebo-controlled trial, all patients were treated with six cycles of CAF therapy. Patients received Dof (900 mg p.o.) 30 min before doxorubicin. The primary endpoint was overall response rate (partial or complete response). In total, 221 patients were evaluable. The overall response rate was 42.6% for CAF alone versus 53.1% for Dof + CAF. Although the response rate improved by more than 10% with the combination of Dof + CAF, it was not statistically significant. Initially, we were expecting more than 20% improvement in the overall response rate. However, Dof significantly improved progression-free survival in patients who were premenopausal (P=0.046), who had received no prior therapy (P<0.01), or patients with advanced (stage IV) primary tumors (P=0.017). In addition, treatment with Dof did not affect the plasma concentration of doxorubicin in patients. These clinical studies indicate that Dof was well tolerated and displayed promising efficacy in patients who had not received prior therapy. The antiestrogens, tamoxifen, and toremifene, may moderate P-gp-related drug resistance in vitro. Toremifene demonstrated a synergistic effect in combination with paclitaxel on various human breast cancer cell lines. Furthermore, a synergistic effect was observed on a multidrug-resistant cell line. This synergistic effect was more potent when paclitaxel was combined with toremifene than with tamoxifen. Clinical benefits in some patients with recurrent breast cancer were reported.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2005

Tankyrase 1 as a target for telomere-directed molecular cancer therapeutics.

Telomere elongation by telomerase is repressed in cis by the telomeric protein TRF1. Tankyrase 1 poly(ADP-ribosyl)ates TRF1 and releases it from telomeres, allowing access of telomerase to telomeres. Here we demonstrate that tankyrase 1 inhibition in human cancer cells enhances telomere shortening by a telomerase inhibitor and hastens cell death. Conversely, either tankyrase 1 upregulation or telomere shortening, each of which decreased TRF1 loading on a chromosome end, attenuated the impact of telomerase inhibition. These results are consistent with the idea that telomeres having fewer TRF1s increase the efficiency of their elongation by telomerase. This study implies that both enzyme activity and accessibility to telomeres can be targets for telomerase inhibition.

Apoptosis↗
PubMed2005

Taxoids and abietanes from callus cultures of Taxus cuspidata.

Seventeen known taxoids and 10 abietanes were isolated from the dark brown callus culture of Taxus cuspidata cultivated on a modified Gamborg's B5 medium with 0.5 or 1.0 mg/L NAA. Seven known taxoids and four abietanes were obtained from the callus culture incubated under light irradiation on the medium with 1.0 mg/L NAA. Eight taxoids and five abietanes were also separated from the callus culture on the medium with 10 mmol/L beta-cyclodextrin and 1.0 mg/L NAA. The new compounds were identified by analyses of the spectroscopic data and were found to be abieta-6,8,11,13-tetraene-3beta,12-diol (1), 3beta,20-epoxy-12-methoxy-abieta-8,11,13-triene-3alpha,11-diol (2), 3alpha-hydroxy-9(10-->20)abeo-abieta-1,5,8,10(20),13-pentaene-7,11,12-trione (3), 2-hydroxy-9(10-->20)abeo-abieta-1,5,8,10(20),13-pentaene-3,7,11,12-tetraone (4), and 3,7-dioxo-9(10-->20)abeo-12-norabieta-1,5,8,10(20),13-pentaene-11,13-lactone (5), respectively. The yield of paclitaxel and its analogues was markedly decreased in the calluses mentioned above compared with that of standard callus. Instead, abietanes and some taxoids related to biosynthesis of paclitaxel were produced. Taxusin (6) exhibited stronger MDR-reversing activity than verapamil toward 2780 AD tumor cells.

Abietanes↗
PubMed2005

Bioactive tetrahydrofuran lignans from Peperomia dindygulensis.

Five new tetrahydrofuran lignans (1-5), accompanied by four known compounds, were isolated from the ethyl acetate extract of Peperomia dindygulensis. Structures were elucidated mainly using 1D NMR, 2D NMR, and mass spectroscopic studies. The relative configurations of 1-5 were determined by NOE correlations. Several of the compounds showed weak growth inhibitory activity against three cell lines (WI-38, VA-13, and HepG2). Compound 5 exhibited stronger MDR (multidrug resistance) reversal activity than verapamil at 2.5 microg/mL in a cellular calcein accumulation assay. Compounds 4 and 5 showed weak inhibitory activity against induction of the intercellular adhesion molecule-1 (ICAM-1) in anti-inflammatory activity experiments.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2005

Involvement of mitochondrial aggregation in arsenic trioxide (As2O3)-induced apoptosis in human glioblastoma cells.

Arsenic trioxide (As(2)O(3)) is effective against acute promyelocytic leukemia and has potential as a novel treatment against malignant solid tumors. As(2)O(3) induces differentiation and inhibits growth. It also causes mitochondrial damage mediated by the production of reactive oxygen species (ROS) and the dissipation of mitochondrial transmembrane potential (DeltaPsi(m)), leading to apoptosis. Mitochondria might be the key target of antitumor activity by As(2)O(3); however, its mechanisms have not been completely elucidated. Using two human glioblastoma cell lines, A172 and T98G, we found that As(2)O(3) induced apoptosis in A172 cells but not in T98G cells. As(2)O(3)-induced ROS production was observed in both cell lines; however, the dissipation of DeltaPsi(m), Bax oligomerization and caspase activation occurred only in As(2)O(3)-sensitive A172 cells. To determine the mechanisms of As(2)O(3)-induced apoptosis after ROS generation, we examined the change of mitochondrial morphology. As we reported previously, mitochondrial aggregation occurs before cytochrome c release during apoptosis, thus playing a role in cell death progression. We observed mitochondrial aggregation in As(2)O(3)-sensitive A172 cells but not in T98G cells treated with As(2)O(3). Using laser scanning cytometry, we quantitatively confirmed the results, which indicate that mitochondrial aggregation plays an important role in regulating sensitivity to As(2)O(3)-induced apoptosis. We propose a sequential process involving ROS generation, mitochondrial aggregation, Bax oligomerization and DeltaPsi(m) dissipation, and caspase activation during As(2)O(3)-induced apoptosis.

Antineoplastic Agents↗
PubMed2005

Akt/protein kinase B-dependent phosphorylation and inactivation of WEE1Hu promote cell cycle progression at G2/M transition.

The serine/threonine kinase Akt is known to promote cell growth by regulating the cell cycle in G1 phase through activation of cyclin/Cdk kinases and inactivation of Cdk inhibitors. However, how the G2/M phase is regulated by Akt remains unclear. Here, we show that Akt counteracts the function of WEE1Hu. Inactivation of Akt by chemotherapeutic drugs or the phosphatidylinositide-3-OH kinase inhibitor LY294002 induced G2/M arrest together with the inhibitory phosphorylation of Cdc2. Because the increased Cdc2 phosphorylation was completely suppressed by wee1hu gene silencing, WEE1Hu was associated with G2/M arrest induced by Akt inactivation. Further analyses revealed that Akt directly bound to and phosphorylated WEE1Hu during the S to G2 phase. Serine-642 was identified as an Akt-dependent phosphorylation site. WEE1Hu kinase activity was not affected by serine-642 phosphorylation. We revealed that serine-642 phosphorylation promoted cytoplasmic localization of WEE1Hu. The nuclear-to-cytoplasmic translocation was mediated by phosphorylation-dependent WEE1Hu binding to 14-3-3theta but not 14-3-3beta or -sigma. These results indicate that Akt promotes G2/M cell cycle progression by inducing phosphorylation-dependent 14-3-3theta binding and cytoplasmic localization of WEE1Hu.

Cell Cycle↗
PubMed2005

[Cancer screening].

The purpose of cancer screening is to widen the difference between morbidity and mortality of the target cancer. Since 1983 cancer screening has been supported by the Japanese government. Initially it covered gastric and cervical cancer with lung, breast and endometrial cancers supported from 1987 and colorectal cancer in 1992. Since 1998 support for cancer screening has been transferred to local government. It is generally accepted that the uptake of screening services is too low. Estimates for Japan suggest that at best 30% of the eligible population accept the services. In other parts of the world screening is more widely accepted, for example, 67% for breast cancer and 79% for cervical screening in the USA. Barriers within Japan for increasing screening are complex and include, legal, ethical, financial, technical infrastructure, data related matters and the level of understanding and education of the general public. In 2000 the MHLW conducted an evaluation of cancer screening in terms of usefulness and effectiveness. It concluded that fair or better evidence for reduction in mortality existed for cervical cancer (cytology), breast cancer (mammography with clinical examination for women aged > or = 50 years), colorectal cancer (faecal occult blood test), gastric cancer, lung cancer and liver cancer. As a step towards improving screening services and their uptake by the general public a new Research Centre for Cancer Prevention and Screening was established at the National Cancer Centre in October 2003. This and other initiatives will build on the progress of the past 20 years but it is generally agreed that there is still have a long way to go.

Adult↗
PubMed2005

[Cancer prevention].

The 12 th Oncology Forum discussed the progress and future strategy of cancer prevention in Japan. The National Cancer Center has established a research center for screening focusing on the most common six cancer, stomach, lung, liver, colon, breast and uterus cancer. The program so far had a cumulative detection rate of 3.3%, which is high,and may reflect the selection of subjects. Screening and chemoprevention is also being investigated in prostate cancer, but the issues centre on how to make this widely available. High risk subjects can also be identified for breast cancer. Obesity and family history are especially important. In colorectal cancer studies are evaluating different diets, but general application is not yet possible and the infrastructure to implement any general screening and prevention does not exist. Development of pharmaceutical treatments for prevention is difficult because of the need for very safe treatments, and also because of the length of time needed to carry out studies. Overall, cancer prevention is still in evolution. New approaches are needed, and new infrastructure will be needed at a government level to implement this.

Breast Neoplasms↗
PubMed2004

Nitric oxide mediates cyclosporine-induced impairment of the blood-brain barrier in cocultures of mouse brain endothelial cells and rat astrocytes.

The present study was designed to clarify the involvement of nitric oxide (NO) signaling in the adverse effect of cyclosporine on the blood-brain barrier. Cyclosporine increased the permeability of sodium-fluorescein and the cellular accumulation of rhodamine 123, a substrate of P-glycoprotein, in mouse brain endothelial (MBEC4) cells. This effect was markedly enhanced two- to threefold when MBEC4 cells were cocultured with rat astrocytes or C6 glioma cells. Direct and continuous electrochemical measurement of NO demonstrated that cyclosporine dose-dependently increased histamine- and phenylephrine-evoked NO production in MBEC4 cells and astrocytes, respectively. A NO synthase inhibitor (NG-monomethyl-L-arginine) blocked slightly and markedly cyclosporine-induced impairment of the endothelial barrier in the monolayer and coculture system, respectively. These findings suggest that cyclosporine impairs the brain endothelial barrier function by accelerating NO production in the brain endothelial and astroglial cells. This event may be interpreted as triggering the occurrence of cyclosporine neurotoxicity.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2004

Saturable distribution of tacrine into the striatal extracellular fluid of the rat: evidence of involvement of multiple organic cation transporters in the transport.

The kinetics and mechanism by which tacrine is distributed in the rat brain were examined. Tacrine levels in plasma and striatal extracellular fluid were used to evaluate the pharmacokinetics of this process. The K(D,brain) was decreased with the dose for tacrine, indicating that the distribution to the brain is saturable. The uptake of organic cations such as choline, 1-methyl-4-phenylpyridinium (MPP), tetraethylammonium (TEA), and carnitine was inhibited by the addition of tacrine to cultures of mouse immortalized brain capillary endothelial cells. In addition, the apical to basal transport and basal to apical transport of tacrine were inhibited by the addition of organic cations to cultures of LLC-PK1 cells, suggesting that tacrine transport across the blood-brain barrier (BBB) is mediated by organic cation transport system(s). Consistent with the in vitro results, a standard reverse transcription-polymerase chain reaction procedure was able to amplify the message of mOCT2 and mOCTN2, but not mOCT1, in MBEC4 (mouse brain microvessel endothelial cell line 4) cells. Similarly, mRNAs for rOCT2 and rOCTN2 were present in representative rat brain samples. To determine whether OCT2 and/or OCTN2 transport tacrine, these transporters were cloned and then transfected in SK-HEP1 and HEK 293 cells. The uptake of choline, MPP, and TEA was inhibited by the presence of tacrine in rOCT2-expressing SK-HEP1 cells, whereas the uptake of carnitine was inhibited by the presence of tacrine in rOCTN2-expressing HEK 293 cells. Collectively, these observations suggest that the transport of tacrine across the BBB is mediated, at least in part, by multiple organic cation transport systems in rats.

Animals↗
PubMed2004

Aggrus: a diagnostic marker that distinguishes seminoma from embryonal carcinoma in testicular germ cell tumors.

Aggrus (also known as T1alpha/podoplanin) is a membrane sialoglycoprotein whose function in tumors is unknown. We recently determined that Aggrus possessed the ability of inducing platelet aggregation and that its expression was frequently upregulated in colorectal tumors. Thus, Aggrus expression might be associated with tumor-induced platelet aggregation and tumor metastasis. Here we show, by means of cancer profiling array and real-time PCR, that aggrus mRNA expression is frequently upregulated in testicular germ cell tumors when compared with the surrounding normal tissue. Immunohistochemical staining revealed that Aggrus protein expression was detected in 10 of 11 seminomas (90.9%), but its expression was not observed in embryonal carcinomas (0/4; 0%). Specific markers for seminomas have not been reported, and Aggrus is a potential diagnostic marker for seminomas and may be associated with malignancies of the testis.

Animals↗
PubMed2004

Prediction of sensitivity of advanced non-small cell lung cancers to gefitinib (Iressa, ZD1839).

Gefitinib (Iressa, ZD1839), an inhibitor of epidermal growth factor receptor-tyrosine kinase, has shown potent anti-tumor effects and improved symptoms and quality-of-life of a subset of patients with advanced non-small cell lung cancer (NSCLC). However, a large portion of the patients showed no effect to this agent. To establish a method to predict the response of NSCLC patients to gefitinib, we used a genome-wide cDNA microarray to analyze 33 biopsy samples of advanced NSCLC from patients who had been treated with an identical protocol of second to seventh line gefitinib monotherapy. We identified 51 genes whose expression differed significantly between seven responders and 10 non-responders to the drug. We selected the 12 genes that showed the most significant differences to establish a numerical scoring system (GRS, gefitinib response score), for predicting response to gefitinib treatment. The GRS system clearly separated the two groups without any overlap, and accurately predicted responses to the drug in 16 additional NSCLC cases. The system was further validated by the semi-quantitative RT-PCR, immunohistochemistry and ELISA for serological test. Moreover, we proved that the anti-apoptotic activity of amphiregulin, a protein that was significantly over-expressed in non-responders but undetectable in responders, leads to resistance of NSCLC cells to gefitinib in vitro. Our results suggested that sensitivity of a given NSCLC to gefitinib can be predicted according to expression levels of a defined set of genes that may biologically affect drug sensitivity and survival of lung cancer cells. Our scoring system might eventually lead to achievement of personalized therapy for NSCLC patients.

Adult↗
PubMed2004

Transport of somatostatin and substance P by human P-glycoprotein.

P-glycoprotein is an efflux pump for a broad spectrum of hydrophobic agents. We found that bioactive peptides including somatostatin and substance P inhibit ATP-dependent vincristine binding to P-glycoprotein-overexpressing K562/ADM membrane vesicles. Some of these bioactive peptides including somatostatin stimulate basal ATPase activity of P-glycoprotein; in contrast, other peptides including substance P inhibit it. The K562/ADM membrane vesicles showed an ATP-dependent, osmotically sensitive uptake of somatostatin and substance P, which was inhibited by valspodar, an inhibitor of P-glycoprotein. These findings suggested that certain bioactive peptides such as somatostatin and substance P directly interact with human P-glycoprotein as endogenous substrates for P-glycoprotein-mediated transport.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2004

Protein tyrosine phosphatase receptor-type O (PTPRO) exhibits characteristics of a candidate tumor suppressor in human lung cancer.

Previous study in our laboratory demonstrated suppression of the gene for protein tyrosine phosphatase receptor-type O (PTPRO) in primary and established rat hepatomas. The present study showed methylation-mediated silencing of this gene in primary human lung tumors and in several human lung cancer cell lines, one of the characteristics of many tumor-suppressor genes. The reduced expression of PTPRO in the primary lung tumors correlated with the methylation status of its CpG island. Demethylation of the gene by deoxy-5-azacytidine treatment led to its reactivation in a lung cancer line (A549). Overexpression of PTPRO in A549 cells inhibited anchorage-independent growth, delayed reentry of the cells into the cell cycle after release from cell-cycle arrest, and increased susceptibility of the cells to apoptosis. These data have demonstrated the growth-suppressor characteristics of PTPRO that are unique to a classical tumor suppressor.

Base Sequence↗
PubMed2004

Effect on tumor cells of blocking survival response to glucose deprivation.

BACKGROUND: Glucose deprivation, a feature of poorly vascularized solid tumors, activates the unfolded protein response (UPR), a stress-signaling pathway, in tumor cells. We recently isolated a novel macrocyclic compound, versipelostatin (VST), that inhibits transcription from the promoter of GRP78, a gene that is activated as part of the UPR. We examined the effect of VST on the UPR induced by glucose deprivation or other stressors and on tumor growth in vivo. METHODS: Human colon cancer HT-29, fibrosarcoma HT1080, and stomach cancer MKN74 cells were cultured in the absence of glucose or in the presence of glucose and a UPR-inducing chemical stressor (the N-glycosylation inhibitor tunicamycin, the calcium ionophore A23187, or the hypoglycemia-mimicking agent 2-deoxyglucose [2DG]). The effect of VST on UPR induction was determined by reverse transcription-polymerase chain reaction and immunoblot analysis of the UPR target genes GRP78 and GRP94; by immunoblot analysis of the UPR transcriptional activators ATF6, XBP1, and ATF4; and by analyzing reporter gene expression in cells transiently transfected with a GRP78 promoter-reporter gene. Cell sensitivity to VST was examined with a colony formation assay and flow cytometry. In vivo antitumor activity of VST was assessed with an MKN74 xenograft model. RESULTS: VST inhibited expression of UPR target genes in glucose-deprived or 2DG-treated cells but not in cells treated with tunicamycin or A23187. VST also inhibited the production of the UPR transcriptional activators XBP1 and ATF4 during glucose deprivation. The UPR-inhibitory action of VST was seen only in conditions of glucose deprivation and caused selective and massive killing of the glucose-deprived cells. VST alone and in combination with cisplatin statistically significantly (P =.004 and P<.001 for comparisons with untreated control, respectively) inhibited tumor growth of MKN74 xenografts. CONCLUSION: Disruption of the UPR may provide a novel therapeutic approach to targeting glucose-deprived solid tumors.

Activating Transcription Factor 4↗