PubMed Health⌕ Search

Biomedical subjects

Michihiko Kuwano

Publications and source records attributed to Michihiko Kuwano.

65 records · Page 4Linked to original sources
PubMed2002

Reactive oxygen species accelerate production of vascular endothelial growth factor by advanced glycation end products in RAW264.7 mouse macrophages.

Advanced glycation end products (AGEs) are believed to play an important role in the development of angiopathy in diabetes mellitus. Previous reports suggested a correlation between accumulation of AGEs and production of vascular endothelial growth factor (VEGF) in human diabetic retina. However, the mechanisms involved were not revealed. In this study, we investigated the transcriptional regulation of the expression of vascular endothelial growth factor (VEGF) by AGEs, and possible involvement of reactive oxygen species (ROS) in the induction. We employed an AGE of bovine serum albumin (BSA) prepared by an incubation of BSA with D-glucose for 40 weeks and N(epsilon)-(carboxymethyl)lysine (CML), a major AGE. The expression of VEGF was induced by CML-BSA in RAW264.7 mouse macrophage-like cells. CML-BSA stimulated the DNA-binding activity of activator protein-1 (AP-1). Promoter assay showed that the induction of VEGF was dependent on AP-1. The activity of Ras/Raf-1/MEK/ERK1/2 was involved in the CML-BSA-stimulated signaling pathways to activate the AP-1 transcription with a peak at 1 h. AGE-BSA also induced VEGF mediated by AP-1, however, there was a difference of effect between AGE-BSA and CML-BSA in the activation of AP-1. AGE-BSA-stimulated AP-1 activity showed a peak at 5 h, which paralleled the formation of ROS. Reduction of AGE-BSA with NaBH(4) or addition of vitamin E attenuated the AGE-BSA-stimulated signaling pathways leading to the same pattern as for CML-BSA-stimulated signals. These results suggest an important role for AGEs in stimulation of the development of angiogenesis observed in diabetic complications, and that ROS accelerates the AGE-stimulated VEGF expression.

Animals↗
PubMed2002

Increased expression of multidrug resistance-associated proteins in bladder cancer during clinical course and drug resistance to doxorubicin.

Overexpression of the P-glycoprotein/multidrug resistance 1 (MDR1) and multidrug resistance protein 1 (MRP1) gene is closely associated with the clinical outcome of various malignancies, and it is involved in responses to some anticancer chemotherapeutic agents including doxorubicin. Six human MRP subfamily members (MRP2-7) with structural similarities to MRP1 have been identified. Recently, the relationships between MRP2 and MRP3 expression levels of some cancer cells and drug sensitivity to doxorubicin have been reported, but the relationship between the clinical samples and drug sensitivity remains unclear. We determined the expressions of the MDR1, MRP1, MRP2 and MRP3 gene in bladder cancer during the clinical course and sought to learn whether the expression was correlated with drug responses to doxorubicin. Doxorubicin, used in chemotherapeutic treatment including intravesical and systemic chemotherapy, is an important anticancer agent for the treatment of bladder cancer. We used quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis for our study, and the sensitivity to doxorubicin in bladder cancer was determined using the in vitro succinate dehydrogenase inhibition test. Using 47 clinical samples of bladder cancer, we confirmed the significant correlation of MDR1, MRP1 and MRP3 mRNA levels with resistance to doxorubicin. We showed that the expression of MDR1, MRP1, MRP2 and MRP3 in recurrent tumors and residual tumors after chemotherapeutic treatment was higher than that in untreated primary tumors. In particular, the MDR1 expression in residual tumors was 5.7-fold higher than that in untreated primary tumors.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2002

Up-regulation of thrombospondin-1 gene by epidermal growth factor and transforming growth factor beta in human cancer cells--transcriptional activation and messenger RNA stabilization.

Thrombospondin-1 (TSP-1), a multifunctional matrix protein, affects tumor growth through modulation of angiogenesis and other stromal biological functions. In several of nine human cancer cell lines derived from liver, brain, pancreas, and bone, expression of TSP-1 was up-regulated in response to the two most representative growth factors, epidermal growth factor (EGF) and transforming growth factor beta1 (TGFbeta1). Expression of TSP-1 was markedly enhanced in hepatic HuH-7 cells by EGF but not by TGFbeta1. In contrast, expression of TSP-1 was markedly enhanced by TGFbeta1, but not by EGF, in osteosarcoma MG63 cells. EGF induced activation of TSP-1 promoter-driven luciferase activity in HuH-7 cells, and the elements between -267 and -71 on the 5' region of TSP-1 gene containing two GC boxes to which Sp1 bound, were found to be responsible for the promoter activation by EGF. However, EGF did not alter TSP-1 mRNA stability in hepatic cells. On the other hand, no such enhancement of the TSP-1 promoter activity by TGFbeta1 appeared in MG63 cells. Enhanced expression of TSP-1 by TGFbeta1 in MG63 cells was partially blocked by exogenous addition of SB203580, an inhibitor of p38 mitogen-activated protein kinase. TGFbeta was found to induce marked elongation of TSP-1 mRNA longevity in osteosarcoma cells when mRNA degradation was assayed in the presence of alpha-amanitin. The up-regulation of TSP-1 by EGF and TGFbeta might play a critical role in modulation of angiogenesis and formation of matrices in tumor stroma.

Bone Neoplasms↗
PubMed2002

Bryoanthrathiophene, a new antiangiogenic constituent from the bryozoan Watersipora subtorquata (d'Orbigny, 1852).

A new antiangiogenic compound, bryoanthrathiophene (1), together with two known compounds, 5,7-dihydroxy-1-methoxycarbonyl-6-oxo-6H-anthra[1,9-bc]thiophene (2) and 1,8-dihydroxyanthraquinone (3), was isolated from the bryozoan Watersipora subtorquata (d'Orbigny, 1852) using bioassay-guided fractionation methods. Among them, bryoanthrathiophene (1) exhibited the most potent antiangiogenic activity on BAEC (bovine aorta endothelial cell) proliferation.

Angiogenesis Inhibitors↗
PubMed2002

Trafficking and functional defects by mutations of the ATP-binding domains in MRP2 in patients with Dubin-Johnson syndrome.

Dubin-Johnson syndrome (DJS) is a hereditary disease characterized by hyperbilirubinemia. We investigated the consequences of 2 missense mutations, R768W and Q1382R, of nucleotide-binding domains (NBDs) of the multidrug resistance protein 2 (MRP2; ABCC2) that were previously identified in patients with DJS. Pulse chase analysis revealed that the precursor form of the wild-type and Q1382R MRP2 were converted to the mature form, which is resistant to endoglycosidase H (Endo H) in about 60 minutes. However, the precursor form of the R768W MRP2, which is sensitive to endoglycosidase H, was degraded within 120 minutes and did not mature to the fully glycosylated form. Proteasome inhibitors inhibited the degradation of the precursor form of the R768W MRP2. Unlike the R768W MRP2, the Q1382R MRP2 was mainly localized on the apical membrane in the wild-type form. However, efflux of glutathione monochlorobimane (GS-MCLB) and ATP-dependent leukotriene C(4) (LTC(4)) uptake into plasma membrane vesicles from cells expressing the Q1382R MRP2 were markedly reduced, suggesting that the Q1382R MRP2 on the apical membrane was nonfunctional. Vanadate-induced nucleotide trapping with 8-azido-[alpha-32P]ATP in the wild-type MRP2 was stimulated by estradiol glucuronide (E(2)17betaG) in a concentration-dependent manner but that in the Q1382R MRP2 was not. In conclusion, the R768W mutation causes deficient maturation and impaired sorting, and the Q1382R mutation does not affect maturation or sorting but impairs the substrate-induced ATP hydrolysis.

Adenosine Triphosphate↗
PubMed2002

Novel translational control through an iron-responsive element by interaction of multifunctional protein YB-1 and IRP2.

The eukaryotic Y-box-binding protein YB-1 functions in various biological processes, including DNA repair, cell proliferation, and transcriptional and translational controls. To gain further insight into how human YB-1 plays its role in pleiotropic functions, we here used two-hybrid screenings to identify partners of this protein; the results showed that YB-1 itself, iron-regulatory protein 2 (IRP2), and five ribosomal proteins each served as partners to YB-1. We then examined the biological effect of the interaction of YB-1 and IRP2 on translational regulation. Both in vitro binding and coimmunoprecipitation assays showed the direct interaction of YB-1 and IRP2 in the presence of a high concentration of iron. RNA gel shift assays showed that YB-1 reduced the formation of the IRP2-mRNA complex when the iron-responsive element of the ferritin mRNA 5' untranslated region (UTR) was used as a probe. By using an in vitro translation assay using luciferase mRNA ligated to the ferritin mRNA 5'UTR as a reporter construct, we showed that both YB-1 and IRP2 inhibited the translation of the mRNA. However, coadministration of YB-1 and IRP2 proteins abrogated the inhibition of protein synthesis by each protein. An In vivo coimmunoprecipitation assay showed that IRP2 bound to YB-1 in the presence of iron and a proteasome inhibitor. The direct interaction of YB-1 and IRP2 provides the first evidence of the involvement of YB-1 in the translational regulation of an iron-related protein.

5' Untranslated Regions↗
PubMed2002

Contribution of P-glycoprotein to efflux of ramosetron, a 5-HT3 receptor antagonist, across the blood-brain barrier.

In-situ rat and mouse brain perfusion data indicated that the brain distribution of ramosetron (R-ramosetron), a 5-hydroxytryptamine3 (5-HT3) receptor antagonist, was extremely low compared with that expected from its lipophilicity. We hypothesized the involvement of an efflux system(s) and investigated the contribution of P-glycoprotein to efflux transport of ramosetron across the blood-brain barrier by means of an in-vitro uptake study in cell lines that over-express P-glycoprotein. We examined the contributions of mdr1a, mdr1b and MDR1 P-glycoprotein by using LV500 cells, MBEC4 cells and LLC-GA5-COL300 cells, which over-express mdr1a P-glycoprotein, mdr1b P-glycoprotein and MDR1 P-glycoprotein, respectively. The uptake of [14C]ramosetron by LV500 cells and LLC-GA5-COL300 cells was significantly lower than that by the respective parental cells. Next, we studied the effects of P-glycoprotein inhibitors, verapamil and ciclosporin, on uptake of [14C]ramosetron by these cell lines. The uptake of [14C]ramosetron by LV500 cells and LLC-GA5-COL300 cells was significantly increased in the presence of verapamil or ciclosporin, while verapamil did not affect the uptake of [14C]ramosetron by MBEC4 cells. These results indicate that the efflux of [14C]ramosetron is partly mediated by mdr1a P-glycoprotein, but not by mdr1b P-glycoprotein, and that there is a difference in substrate specificity between mdr1a P-glycoprotein and mdr1b P-glycoprotein. Further, [14C]ramosetron was confirmed to be effluxed by human MDR1 P-glycoprotein. We conclude that the limited distribution of ramosetron to the brain is due, at least in part, to efflux mediated by the P-glycoprotein at the blood-brain barrier.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2002

A functional polymorphism in fas (CD95/APO-1) gene promoter associated with systemic lupus erythematosus.

OBJECTIVE: To investigate whether Fas promoter polymorphisms show a genetic contribution to the development of systemic lupus erythematosus (SLE) in a Japanese population, and to study the functional difference in promoter activity of the polymorphisms. METHODS: In 109 SLE patients and 140 controls, the frequencies of A/G polymorphisms at -670 nucleotide position and G/A at -1377 nucleotide position were determined by allele-specific polymerase chain reaction (PCR) or PCR-single strand conformation polymorphism analysis. The functional significance of the -670A/G polymorphism in the Fas gene was evaluated by a combination of Fas transcriptional activity in the reporter gene assay and binding activity of signal transducer and activator of transcription (STAT) 1 protein in the electrophoretic mobility shift assay. RESULTS: SLE patients exhibited significantly higher frequency of A allele at nucleotide position -670 (p = 0.004). There was no significant difference in the nucleotide position -1377 in Fas promoter gene between SLE patients and controls. The electrophoretic mobility shift assay demonstrated that the oligonucleotide with -670A in the Fas promoter had a higher binding ability to a GAS binding protein, STAT1, than that with -670G, although there was no statistically significant difference in the reporter gene assay. CONCLUSION: Fas promoter -670A/G polymorphism was significantly associated with SLE, suggesting a possibility that Fas promoter contributes, at least in part, to the pathogenesis of SLE.

Alleles↗
PubMed2002

ATP-binding cassette superfamily transporter gene expression in human primary ovarian carcinoma.

PURPOSE: The purpose of this study is to attempt to characterize patients with unfavorable clinical outcome by the relative mRNA levels of ABC transporter expression in their tumor samples and to examine whether relative mRNA levels of each of the ABC transporters can be a useful predictor of progression-free survival in advanced ovarian carcinoma. EXPERIMENTAL DESIGN: We examined tumor samples taken from 30 patients with primary serous papillary adenocarcinoma of the ovary for the expression of MDR1 and MRP1, MRP2, and MRP3 mRNA by using real-time reverse transcription-PCR, and we evaluated its correlation with clinical outcome. All 30 patients were divided into three groups according to clinical outcome after debulking surgery and platinum-based chemotherapy: 8 patients were classified into the unfavorable group; 11 were classified into the favorable group; and 11 were classified into intermediate group. RESULTS: The relative mRNA levels of MRP1 and MRP3 were significantly different among the three groups, and the mRNA levels of MRP1 and MRP3 in the unfavorable group were significantly higher than those in the favorable group by multiple comparison. The relative mRNA levels of MRP1 expression were significantly correlated with those of MRP3 expression. In the 30 patients with serous papillary adenocarcinoma, univariate and multivariate analysis demonstrated that the high relative mRNA levels of MRP1 expression were significantly correlated with a short period of progression-free survival. CONCLUSIONS: In patients with advanced ovarian serous papillary adenocarcinoma, these results suggest that patients with an unfavorable clinical outcome are characterized by increased levels of coordinated MRP1 and MRP3 mRNA expression in their tumor samples. Furthermore, a higher level of MRP1 mRNA expression can be a candidate for a useful predictor of a shorter period of progression-free survival.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2002

Antiangiogenic effect by SU5416 is partly attributable to inhibition of Flt-1 receptor signaling.

Interaction between vascular endothelial growth factor (VEGF) and its cognate receptors, KDR/Flk-1 and Flt-1, of vascular endothelial cells is expected to induce an angiogenesis "switch" in tumors and other angiogenesis-associated diseases. SU5416, a selective inhibitor of the KDR/Flk-1 tyrosine kinase, is known to be a potent inhibitor of tumor angiogenesis. In this study, we first observed that SU5416 inhibited Flt-1 tyrosine kinase activity at similar doses, in addition to inhibiting KDR/Flk-1 tyrosine kinase activity in response to VEGF. SU5416 inhibited cell migration of human vascular endothelial cells expressing both Flt-1 and KDR in response to VEGF and also inhibited the cell migration in response to placenta growth factor (PIGF), a specific ligand for Flt-1. Chemotaxis of monocytes expressing only Flt-1 was also inhibited by SU5416 in a dose-dependent manner. Moreover, SU5416 was found to inhibit tyrosine kinase of Flt-1 in response to PIGF in vitro. And angiogenesis induced by PIGF in a Matrigel plug assay was inhibited by administration of SU5416. The antiangiogenic effects by this VEGF receptor-targeting compound appeared to be mediated through interference not only with KDR/Flk-1 but also with Flt-1. Cell migration of vascular endothelial cells and monocytic cells through Flt-1, thus, might play a key role in VEGF-induced tumor angiogenesis in concert with KDR/Flk-1.

3T3 Cells↗