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Biomedical subjects

Mitsuru Ishikawa

Publications and source records attributed to Mitsuru Ishikawa.

31 records · Page 2Linked to original sources
PubMed2005

A history of microarrays in biomedicine.

The fundamental strategy of the current postgenomic era or the era of functional genomics is to expand the scale of biologic research from studying single genes or proteins to studying all genes or proteins simultaneously using a systematic approach. As recently developed methods for obtaining genome-wide mRNA expression data, oligonucleotide and DNA microarrays are particularly powerful in the context of knowing the entire genome sequence and can provide a global view of changes in gene expression patterns in response to physiologic alterations or manipulation of transcriptional regulators. In biomedical research, such an approach will ultimately determine biologic behavior of both normal and diseased tissues, which may provide insights into disease mechanisms and identify novel markers and candidates for diagnostic, prognostic and therapeutic intervention. However, microarray technology is still in a continuous state of evolution and development, and it may take time to implement microarrays as a routine medical device. Many limitations exist and many challenges remain to be achieved to help inclusion of microarrays in clinical medicine. In this review, a brief history of microarrays in biomedical research is provided, including experimental overview, limitations, challenges and future developments.

Animals↗
PubMed2005

Ultrafast diagnosis of the genetic-related disorders using the combined technologies of multiplex PCR and multichannel microchip electrophoresis.

For the diagnosis of unexplained male infertility a multiplex PCR for 6 markers, which are well-known as candidate genes for studying male infertility and located on the human Y-chromosome, has been designed. The multiplex PCR products have been separated on a 12 channel microchip electrophoresis system, which can analyze different samples simultaneously. By combining the technologies of multiplex PCR with multichannel microchip electrophoresis, the number of the DNA markers that can be screened simultaneously is increased to be 72 marker (12 x 6) in a single run while the electrophoresis analysis time is reduced to be only 180 s.

Electrophoresis, Microchip↗
PubMed2004

Inhibition of bcr-abl and/or c-abl gene expression by small interfering, double-stranded RNAs: cross-talk with cell proliferation factors and other oncogenes.

BACKGROUND: Short, 21-mer, double-stranded/small interfering RNAs (ds/siRNAs) were designed to target bcr-abl mRNA in chronic myelogenous leukemia (CML) with a potential also to target c-abl mRNA. METHODS: ds/siRNAs were transfected into bcr-abl-positive K-562 cells (derived from blast-crisis) or bcr-abl-negative/c-abl-positive Jurkat cells (derived from acute lymphoblastic leukemia) using lipofectamine. ds/siRNAs intracellular uptake was detected by fluorescent confocal microscopy using fluorescein-labeled ds/siRNAs. The treatment was performed over 6 days with repetitive siRNA transfections. Efficiency of the siRNAs was determined 24 hours after single siRNA transfection and 6 days after repetitive siRNA transfections. RESULTS: Two of the designed ds/siRNAs decreased the target mRNA levels markedly (determined by reverse transcriptase-polymerase chain reaction analysis) and bcr-abl/c-abl oncoproteins (determined by flow cytometry using Fluor-488-labeled, anti-c-abl antibody as well as by Western blot analysis). These sequences also inhibited protein tyrosine kinase activity significantly and suppressed cell proliferation. One of the three selected ds/siRNAs expressed only slight effects on the bcr-abl/c-abl mRNA in K-562 cells (but not on the oncoprotein level), on protein tyrosine kinase activity, and on cell proliferation. The combination of the three ds/siRNA constructs provoked stronger decreases in bcr-abl/c-abl mRNAs and their respective oncoproteins and produced the strongest suppression of cell proliferation. CONCLUSIONS: The cross-talk between siRNA interference of bcr-abl oncogene and the expression of several apoptotic/antiapoptotic factors, cell proliferation factors, and other oncogenes exists and it was determined by microarray analysis in K-562 cells that were treated over 6 days.

Base Sequence↗
PubMed2004

Enhancement of the photoluminescence of CdSe quantum dots during long-term UV-irradiation: privilege or fault in life science research?

The present study describes an impressive enhancement of the photoluminescence (PL) intensity of low-temperature synthesized CdSe nanocrystals (75 degrees C) during long-term UV-irradiation. The integrated PL-intensity of CdSe core and CdSe/ZnS core/shell nanocrystals, dispersed in chloroform, enhanced about 3 and 6 times, respectively, during 9 h exposure to UV-light, without any significant changes in the characteristic absorbance spectra and shifting of PL-spectra. After termination of the irradiation a comparatively slow photobleaching was detected with tau(1/2) = 6 h for CdSe core and tau(1/2) = 14 h for CdSe/ZnS core/shell nanocrystals. The most impressive was the effect of UV-irradiation on the photoluminescence of water-soluble CdSe nanocrystals. The integrated PL-intensity enhanced about 10 times during 11 h exposure to UV-light and the improved PL-intensity was preserved during 3 days after termination of the irradiation without any significant photobleaching. The results are discussed in the context of application of CdSe nanocrystals as novel fluorophores in life science experiments.

Biological Science Disciplines↗
PubMed2004

Suppression of bcr-abl synthesis by siRNAs or tyrosine kinase activity by Glivec alters different oncogenes, apoptotic/antiapoptotic genes and cell proliferation factors (microarray study).

Short 21-mer double-stranded/small-interfering RNAs (ds/siRNAs) were designed to target bcr-abl mRNA in chronic myelogenous leukemia. The ds/siRNAs were transfected into bcr-abl-positive K-562 (derived from blast crisis chronic myelogenous leukemia), using lipofectamine. Penetrating of ds/siRNAs into the cells was detected by fluorescent confocal microscopy, using fluorescein-labeled ds/siRNAs. The cells were treated with mix of three siRNA sequences (3 x 60 nM) during 6 days with three repetitive transfections. The siRNA-treatment was accompanied with significant reduction of bcr-abl mRNA, p210, protein tyrosine kinase activity and cell proliferation index. Treatment of cells with Glivec (during 8 days with four repetitive doses, 180 nM single dose) resulted in analogous reduction of cell proliferation activity, stronger suppression of protein tyrosine kinase activity, and very low reduction of p210. siRNA-mix and Glivec did not affect significantly the viability of normal lymphocytes. Microarray analysis of siRNA- and Glivec-treated K-562 cells demonstrated that both pathways of bcr-abl suppression were accompanied with overexpression and suppression of many different oncogenes, apoptotic/antiapoptotic and cell proliferation factors. The following genes of interest were found to decrease in relatively equal degree in both siRNA- and Glivec-treated cells: Bcd orf1 and orf2 proto-oncogene, chromatin-specific transcription elongation factor FACT 140-kDa subunit mRNA, gene encoding splicing factor SF1, and mRNA for Tec protein tyrosine kinase. siRNA-mix and Glivec provoked overexpression of the following common genes: c-jun proto-oncogene, protein kinase C-alpha, pvt-1 oncogene homologue (myc activator), interleukin-6, 1-8D gene from interferon-inducible gene family, tumor necrosis factor receptor superfamily (10b), and STAT-induced STAT inhibitor.

Antineoplastic Agents↗
PubMed2004

Atypical protein-kinase Czeta, but neither conventional Ca2+ -dependent protein-kinase C isoenzymes nor Ca2+ -calmodulin, participates in regulation of telomerase activity in Burkitt's lymphoma cells.

PURPOSE: To clarify the role of the pathways dependent on protein-kinase C (PK-C) and Ca2+/calmodulin (CaM) in the regulation of telomerase activity in Burkitt's lymphoma cells. METHODS: Burkitt's lymphoma cells (Raji and Daudi) were treated with the PK-C inhibitor, bisindolylmaleimide (BIM), or the CaM inhibitor, trifluoperazine (TFPZ), in a dose-dependent manner and in a time-dependent manner. The activities of PK-C isoenzymes were analyzed fluorimetrically using POLARIS assay kits. CaM-kinase II activity was analyzed radiographically, using CaMK-II immunoprecipitation kinase assay kits. Telomerase activity was detected by a conventional telomeric repeat amplification protocol and Stretch PCR. The level of catalytic subunit of telomerase (hTERT) in drug-treated and nontreated cells was analyzed by flow cytometry using anti-hTERT antibody labeled with ZenonAlexa Fluor-488 IgG. Apoptosis was estimated in terms of phosphatidylserine exposure on the cell surface and DNA fragmentation. RESULTS: It was found that BIM inhibited telomerase activity and this process preceded apoptosis. The subsequent addition of exogenous PK-C (mixture of isoenzymes) to the cell lysates restored telomerase activity if incubation of cells with BIM was up to 24 h. Using PK-C isoenzymes, it was established that atypical PK-Czeta, but not conventional Ca2+ -dependent PK-Calpha, PK-Cbeta or PK-Cgamma, is responsible for the reactivation of telomerase in BIM-treated cells. BIM also showed a well-expressed cytotoxicity against intact leukemia cells. In contrast, the CaM inhibitor TFPZ showed the same cytotoxic effect without any influence on telomerase activity during incubation for 24 h with leukemia cells. After incubation for 48 h, TFPZ markedly suppressed telomerase activity. However, the effect followed apoptosis and appeared to be a result of cell death. The addition of exogenous CaMK-II to the cell lysates obtained from TFPZ-treated cells did not reactivate telomerase. CONCLUSION: The present study confirmed the participation of atypical PK-Czeta, but not conventional Ca2+ -dependent PK-C isoenzymes (alpha, beta, gamma) nor the Ca2+/CaM-dependent pathway, in the regulation of telomerase activity in Burkitt's lymphoma cells.

Apoptosis↗
PubMed2004

Antisense inhibition of Bcr-Abl/c-Abl synthesis promotes telomerase activity and upregulates tankyrase in human leukemia cells.

Clinical studies in chronic myelogenous leukemia demonstrate that the overexpression of Bcr-Abl tyrosine kinase is usually accompanied by relatively low telomerase activity in the chronic phase, which reverts to a high activity in blast crisis. The present study was designed to investigate the cross-talk between both enzymes, using Bcr-Abl-positive K-562 and Bcr-Abl-negative Jurkat cell lines, treated with antisense oligodeoxyribonucleotides (ODNs) against Bcr-Abl/c-Abl mRNA. The decreased amount and enzyme activity of Bcr-Abl/c-Abl provoked telomerase activation in both cell lines. After short-term treatment with anti-Bcr-Abl/c-Abl ODNs (6 days), no variations in hTERT and phospho-hTERT were detected. The decreased amount of Bcr-Abl/c-Abl was accompanied by: alterations in telomeric associated proteins-overexpression of tankyrase and decreased amount of TRF1/Tin2, cell growth arrest of K-562 cells, reaching a plateau after 6 days treatment, and increased proliferating activity of Jurkat cells. No changes in telomere length were detected after short-term treatment. In contrast, after long-term treatment with anti-Bcr-Abl/c-Abl ODNs (36 days), a significant elongation of telomeres and enhancement of hTERT were established, accompanied by an increased proliferating activity of both cell lines. These data provide evidence that the inhibition of Bcr-Abl or c-Abl synthesis keeps a potential to restore or induce cell proliferation through telomere lengthening control and telomerase activation.

Base Sequence↗
PubMed2003

Phenothiazines suppress proliferation and induce apoptosis in cultured leukemic cells without any influence on the viability of normal lymphocytes. Phenothiazines and leukemia.

PURPOSE: The purpose of the present study was to investigate the effects of phenothiazines (at clinically relevant doses) on the viability and proliferation of leukemic cell lines and normal lymphocytes, and to investigate the possibility of specific induction of apoptosis in leukemic cells. METHODS: Phenothiazines with different chemical structure and hydrophobicity were used: chlorpromazine (CPZ); levomepromazine (LVPZ); prometazine (PMZ); trifluoperazine (TFPZ); thioridazine (TRDZ). The leukemic cell lines used were: Daudi and Raji (derived from Burkitt's lymphoma), K-562 (derived from myelogenous leukemia), and BALL-1, MOLT-4, HPB-ALL and CCRF-HSB-2 (derived from acute lymphoblastic leukemia). The cytotoxicity of the phenothiazines was determined by a CellTiter-Glo luminescent cell viability assay, using ATP bioluminescence as a marker of cell viability as well as a marker of mitochondrial activity. The proliferation of leukemic cells was determined using a CellTiter-AQ cell proliferation assay which is based on the reduction of a methyl-tetrazolium compound to the formazan product. Apoptosis induction was estimated using phosphatidylserine (PSer) translocation to the cell surface and DNA fragmentation as characteristics of the process. RESULTS: Phenothiazines (at concentrations in the range 0.1-10 micro M) did not affect the viability of normal lymphocytes during a 24-h incubation. Moreover, about 15-20% increase in ATP bioluminescence was observed in normal cells during treatment with 40 micro M phenothiazines. In contrast, the phenothiazines manifested strong cytotoxicity and antiproliferative activity against leukemic cells. The most powerful drugs were TFPZ and TRDZ, followed by CPZ. They showed a significant cytotoxic effect against leukemic cells even at 5-10 micro M. The most sensitive cell lines were MOLT-4 and Raji, and the most resistant were HPB-ALL and CCRF-HSB-2. All phenothiazines induced PSer exposure on the surface of leukemic cells, but not of normal lymphocytes. TFPZ, TRDZ and CPZ also induced DNA fragmentation in almost all leukemic cell lines during a 48-h incubation. The strongest apoptotic agent was TRDZ. The apoptosis induction was not accompanied by a significant release of cytochrome c from the mitochondria into the cytoplasm of native cells. Moreover, the drugs markedly suppressed Ca(2+)-induced cytochrome c release in isolated mitochondria of leukemic cells. CONCLUSIONS: The results suggest that in clinically relevant doses (up to 20 micro M) some phenothiazines (TFPZ, TRDZ, CPZ) expressed a selective cytotoxicity and antiproliferative activity, and induced apoptosis in leukemic cells without any influence on the viability of normal lymphocytes. It is considered that the mechanism of apoptosis induction in phenothiazine-treated leukemic cells is associated with inhibition of mitochondrial DNA polymerase and decreased ATP production, which are crucial events for the viability of cancer cells.

Adenosine Triphosphate↗
PubMed2003

Cross-talk between Bcr-Abl tyrosine kinase, protein kinase C and telomerase-a potential reason for resistance to Glivec in chronic myelogenous leukaemia.

To prevent the resistance to Glivec in patients with chronic myelogenous leukaemia (CML), it is necessary to get a good understanding of its potential mechanisms. The present hypothesis accents on the mechanisms whereby Bcr-Abl tyrosine kinase remains inhibited by Glivec, but alternative signalling pathways become activated-the potential reason associates with activation of telomerase after long-term treatment with Glivec and recovery of cell proliferation and immortality. The hypothesis is based on the observations about differences in telomere dynamics and telomerase activity between chronic and blast phases of CML patients, as well as about the potential effect of Glivec on the cross-talk between telomerase, Bcr-Abl tyrosine kinase and protein kinase C family-key enzymes in CML. It proceeds from recently published data, demonstrating that protein kinase C activates and c-Abl tyrosine kinase inhibits telomerase. During optimization of chemical structure, Glivec loose its effect on protein kinase C and enhances the effect on Bcr-Abl tyrosine kinase, resulting in a high potential to activate telomerase indirectly through its effect on both kinases. Experimental preclinical data are given in confirmation of this hypothesis.

Antineoplastic Agents↗
PubMed2002

Unique dual fluorescence of sterically congested hexaalkyl benzenehexacarboxylates: mechanism and application to viscosity probing.

The static and dynamic fluorescence behavior of a series of hexaalkyl benzenehexacarboxylates (R(6)BHC; R = methyl (Me), tert-butyl (tBu), (-)-menthyl (Men), (-)-bornyl (Bor), (-)-1-methylheptyl (MHp), neopentyl (neoPn), and 2-adamantyl (Ad)) was studied by steady-state and time-resolved fluorescence spectroscopy. Dual fluorescence from both the partially relaxed metastable Franck-Condon-like (FC') and the fully relaxed (RX) state was observed for tBu(6)BHC, Men(6)BHC, Bor(6)BHC, MHp(6)BHC, neoPn(6)BHC, and Ad(6)BHC, whereas only single fluorescence from the RX state was observed for Me(6)BHC. Picosecond time-resolved fluorescence spectroscopic measurements clearly demonstrated that the initially formed Franck-Condon (FC) state sequentially converts to the FC' and then to RX state, with the relaxation hindered to such an extent that it shows variation with the steric bulk of the R groups. Thus, the fluorescence lifetimes (tau's) of FC' and RX are critically dependent on the bulkiness of the R groups, varying from 17 to 130 ps and from 0.6 to 1.1 ns, respectively. The relative intensity of FC' and RX fluorescence (I(RX)/I(FC)(')) was found to be dependent on the excitation wavelength, suggesting that the conformational relaxation from the FC' to RX state can compete with the vibrational relaxation of the FC' state. The temperature and pressure dependences were studied by steady-state fluorescence spectroscopy to give the activation energies of 1-3 kcal/mol for the FC'-to-RX relaxation of congested R(6)BHCs, as well as the activation volumes of 2.0, -0.62, and 7.4 mL/mol for tBu(6)BHC, Men(6)BHC, and Bor(6)BHC at room temperature. The fluorescence anisotropy (rho), as a measure of molecular motion, was also determined to be in the ranges of 0.03-0.3 for FC' and 0.003-0.01 for RX. The much larger rho's for the FC' fluorescence by a factor of 2-100 are attributed to the shorter tau's. The I(RX)/I(F' ratio was found to be insensitive to solvent polarity, but critically dependent on solvent viscosity, exhibiting an excellent linear relationship with the reciprocal viscosity. The potential use of these sterically congested R(6)BHCs as microenvironmental viscosity probes is proposed.

Journal Article↗
PubMedDate not supplied

Differences in gene expression between noninvasive and invasive transitional cell carcinoma of the human bladder using complementary deoxyribonucleic acid microarray: preliminary results.

This study was performed to identify differences in gene expression between superficial noninvasive and invasive transitional cell carcinoma (TCC) of the bladder in human beings. We used complementary deoxyribonucleic acid microarrays containing 14,551 different genes to analyze gene expression among 6 cases of superficial and 6 cases of invasive TCC of the bladder to identify differences in gene expression, which might explain differences in the biology and clinical outcomes of these histologic subtypes of TCC. Quantitative real-time polymerase chain reaction was performed for selected genes to validate the microarray data. Significant up-regulation of 40 genes was associated with cases of superficial noninvasive, but not in invasive, TCC of the urinary bladder. This effect included genes involved in epithelial cell dedifferentiation and keratinization, as well as genes related to cell cycle, cell adhesion, transcription, and apoptosis. Conversely, significant up-regulation of 34 genes was associated with cases of invasive TCC, but not in superficial TCC, including genes related to extracellular matrix degradation, immune responses, cell cycling, and angiogenesis. This study shows the usefulness of complementary deoxyribonucleic acid microarray technology for identifying differences in gene expression among different histotypes of bladder cancer.

Aged↗