Biomedical subjects

H Sakagami

Publications and source records attributed to H Sakagami.

336 records · Page 19Linked to original sources

PubMedDate not supplied

Uncoupling of incorporation of ascorbic acid and apoptosis induction.

Exposure of human promyelocytic leukemic HL-60 cells to millimolar concentration of sodium ascorbate induced apoptotic cell death. The extent of apoptosis induction was a positive function of temperature at the time of exposure. The incorporation of [1-14C] ascorbic acid into the cytosolic fraction of HL-60 cells was also temperature-dependent, and competitively inhibited by active analogs (L-ascorbic acid, sodium L-ascorbate, D-isoascorbic acid, sodium 6-beta-O-galactosyl-L-ascorbate, sodium 5,6-benzylidene-L-ascorbate), but not by inactive analogs (L-ascorbic acid-2-phosphate magnesium, L-ascorbic acid 2-sulfate). Calcium depletion, which had considerably reduced the apoptosis-inducing activity of sodium ascorbate, did not affect the intracellular incorporation of [14C] ascorbic acid. These data suggests that cell death might not be simply induced by the intracellular incorporation of ascorbate, but rather initiated by the rapid elevation of intracellular Ca2+ concentration, possibly mediated by an as yet unidentified temperature-sensitive mechanism.

Apoptosis↗

PubMedDate not supplied

Induction of DNA fragmentation by nicotine in human myelogenous leukemic cell lines.

The effect of nicotine, a component of tobacco, on the cytokine production and cell growth of various cultured cells was investigated. Nicotine did not stimulate, but rather inhibited the tumor necrosis factor production by human peripheral blood mononuclear cells at higher doses. Cytotoxic concentrations of nicotine did not induce the monocytic and granulocytic differentiation of human myelogenous leukemic cell lines (HL-60, ML-1). Nicotine induced internucleosomal DNA cleavage in these leukemic cell lines but not in human peripheral blood lymphocytes and polymorphonuclear cells. The fragmentation-inducing activity of nicotine was not prevented by simultaneous addition of ascorbic acid. Flow cytometry showed a slight increase in the number of G2 + M phase cells, before the appearance of the apoptosis peak. Nicotine transiently increased the intracellular calcium concentration to higher levels in leukemic cells than in normal leukocytes. These data suggest that the induction of DNA fragmentation requires elevation of intracellular calcium concentration above a certain threshold level.

Ascorbic Acid↗

PubMedDate not supplied

Role of hydrogen peroxide in antitumor activity induction by sodium 5,6-benzylidene-L-ascorbate.

Role of hydrogen peroxide (H2O2) in the induction of antitumor activity against chemically-induced rat hepatocellular carcinoma by sodium 5,6-benzylidene-L-ascorbate (SBA) was investigated. ESR spectroscopy demonstrated that rat liver homogenate of cancerous tissue significantly enhanced the radical intensity of SBA more potently than that of precancerous or normal tissue. The peroxyoxalate chemiluminescence method demonstrated that SBA significantly enhanced the production of H2O2-derived chemiluminescence intensity in the liver homogenates, and the effect of SBA was greater in cancerous tissue than in precancerous or normal tissue. Addition of ascorbic acid, a degradation product of SBA, showed similar but slightly weaker stimulation effects. These data suggest that antitumor activity of SBA in vivo might, at least in part, be due to H2O2 production.

Animals↗

PubMedDate not supplied

Enhancement of radical intensity and cytotoxic activity of ascorbate by Crataegus cuneata Sieb et. Zucc. extracts.

The radical modulation activity of hot water and NaOH extracts of the thorn apple of Crataegus Cuneata Sieb. et. Zucc. was investigated, using ESR spectroscopy. The radical intensity of sodium ascorbate was slightly reduced at lower concentrations of the extracts, but it was synergistically enhanced at higher concentrations. Higher concentrations of the extracts also synergistically stimulated the cytotoxic action of sodium ascorbate against human oral squamous carcinoma and salivary gland tumor cell lines. All these extracts effectively scavenged superoxide anion and hydroxyl radical, produced by hypoxanthine-xanthine oxidase and Fenton reaction, respectively, and their activity was comparable with that of lignins prepared by the same procedure from other plants. These data further supports the medicinal efficacy of plant extracts.

Antineoplastic Agents↗

PubMedDate not supplied

Radical modulation activity of lignins from a mangrove plant, Ceriops decandra (Griff.) Ding Hou.

The radical modulation activity of hot water and alkaline extracts from leaf of Ceriops decandra, a mangrove plant, was investigated using ESR spectroscopy. IR and NMR analyses demonstrate that the leaf extracts have a lignin-like polyphenolic structure. All these extracts produced radical(s) under alkaline conditions. The radical intensity of sodium ascorbate was slightly reduced at lower concentrations of the extracts, but it was synergistically enhanced at higher concentrations. All the extracts effectively scavenged superoxide anion, produced by hypoxanthine-xanthine oxidase reaction. Pretreatment of mice with the extracts significantly protected them from the lethal infection by E. coli. Similar activity was found in lignins from pine seed shell of Pinus parviflora Sieb. et Zucc. These data further support the medicinal efficacy of plant extracts.

Animals↗

PubMedDate not supplied

Expression of somatostatin messenger RNA and receptor in cultured brain tumor cells.

In order to understand the role of somatostatin in tumor cell growth, the expression of somatostatin in 7 cultured brain tumor cells was investigated. Radioimmunoassay demonstrated the production of somatostatin into the culture supernatant of 6 tumor cells. The expression of somatostatin mRNA and receptor was investigated by reverse transcription polymerase chain reaction (RT-PCR) and a binding assay with 125I-somatostatin-14, respectively. Only two cell lines, GBS-1 and U87MG, expressed somatostatin mRNA, whereas somatostatin receptor was expressed in all cultured cells. These results suggest that somatostatin is an important factor for regulating cell growth.

Brain Neoplasms↗

PubMedDate not supplied

Inhibition by Porphyromonas gingivalis LPS of apoptosis induction in human peripheral blood polymorphonuclear leukocytes.

Many factors, such as cytokines and bacterial products, are known to affect the life-span of polymorphonuclear leukocytes (PMNs). We investigated here whether Porphyromonas gingivalis (P.gingivalis) LPS slows down the apoptotic process of PMNs. During incubation in regular culture medium, the viability of PMNs progressively declined, producing apoptotic cells, characterized by chromatin condensation, internucleosomal DNA fragmentation, cell shrinkage and blebbing of plasma membrane. P.gingivalis LPS significantly increased the viability of PMNs and reduced the production of fragmented DNA, as efficiently as E.coli LPS. The present study suggests that the retardation of PMNs apoptosis by P.gingivalis LPS may modulate the restoration of acute inflammation in the periodontal tissues, where activated PMNs accumulate.

Apoptosis↗

PubMedDate not supplied

Radical intensity and cytotoxic activity of curcumin and gallic acid.

Natural phenolic compounds, curcumin and gallic acid, were compared for their cytotoxic activity in relation to their radical modulating activity. These two compounds induced apoptotic cell death in human promyelocytic leukemic HL-60 cells and human oral squamous carcinoma HSC-4 cells. Curcumin was more cytotoxic than gallic acid. Catalase reduced significantly the cytotoxic activity of gallic acid, but not that of curcumin. ESR spectroscopy demonstrated that curcumin produced radicals under alkaline conditions, scavenged the superoxide anion radical, and enhanced the radical intensity of sodium ascorbate at higher concentrations. As compared with curcumin, gallic acid produced higher amounts of radicals and more efficiently scavenged the superoxide anion radical. Gallic acid reduced the radical intensity of sodium ascorbate, suggesting a possible interaction between these two compounds. These data suggest that curcumin and gallic acid induce apoptosis by different mechanisms.

Antineoplastic Agents↗

PubMedDate not supplied

Interaction between sodium 5,6-benzylidene-L-ascorbate and dopamine.

The interaction between sodium 5,6-benzylidene-L-ascorbate (SBA) and dopamine was investigated by three different parameters: radical intensity, prooxidant action and cytotoxic activity. Under alkaline conditions, SBA and dopamine produced doublet and quartet ESR signals, respectively. The addition of increasing concentrations of SBA completely scavenged the dopamine radical and replaced the latter with its own radical. On the other hand, dopamine accelerated the decay of SBA radical. These two compounds stimulated the methionine oxidation in culture medium, but in combination, their stimulation activities were weakened. Both of these two compounds dose-dependently reduced the viable cell number of human promyelocytic leukemics HL-60 cells. When these two compounds were mixed together before adding to HL-60 cells, both of their cytotoxic activities were diminished. The present study demonstrates the interaction between SBA and dopamine, which might modify their biological activities.

Antineoplastic Agents↗

PubMedDate not supplied

Amino acid utilization during cell growth and apoptosis induction.

The amino acid utilization between human promyelocytic leukemia (HL-60), human oral squamous carcinoma (HSC-2, HSC-4, NA), human salivary gland tumor (HSG) and rat neuron cells (PC-12) were compared, using amino acid analyzer. All these cells consumed four essential amino acids (valine, methionine, isoleucine, leucine), glutamine and arginine, whereas they produced glycine, alanine and ammonia, without significantly affecting threonine, tyrosine, phenylalanine, histidine or lysine concentration. Serine and glutamine utilization varied considerably from cell to cell. HL-60 cells consumed serine and arginine at much higher rates than other cells. Serine depletion accumulated the G1 arrested cells, and produced increasing numbers of the apoptotic cells. Supplementation of serine significantly extended the period of logarithmic cell growth. During apoptosis induction of HL-60 cells by dopamine, sodium ascorbate or sodium 5,6-benzylidene-L-ascorbate, the oxidation of methionine to methionine sulfoxide was enhanced, but the consumption of serine, glutamine and arginine was reduced. In the presence of HL-60 cells, the methionine oxidation was significantly inhibited, suggesting the antioxidant action of the cells. These present study suggests the importance of re-evaluation of culture condition for each cell lines.

Amino Acids↗

PubMedDate not supplied

Role of hydrogen peroxide in cytotoxicity induction by ascorbates and other redox compounds.

Role of hydrogen peroxide (H2O2) in the induction of cytotoxicity by ascorbic acid derivatives was investigated. Ascorbic acid derivatives which produced radicals (sodium 5,6-benzylidene-L-ascorbate (SBA), sodium-L-ascorbate, D-isoascorbic acid) dose-dependently reduced the viable cell number of human squamous carcinoma (HSC-2, HSC-4, NA), human salivary gland tumor (HSG) and human promyelocytic leukemia (HL-60) cell lines. Conversely, L-ascorbic acid-2-phosphate magnesium which did not produce radicals, was inactive. This suggests the possible role of the ascorbate radical in apoptosis induction. The cytotoxic activity of SBA was partially reduced by catalase, and the extent of inhibition by catalase was considerably different, depending upon which target cells were used. On the other hand, the cytotoxic activity of sodium ascorbate, isoascorbic acid, hydrogen peroxide and gallic acid was more effectively inhibited by catalase. These data suggest that mechanisms other than H2O2 might be involved in the induction of cytotoxicity by SBA.

Antineoplastic Agents↗

PubMedDate not supplied

Induction of apoptosis by cooperative action of vitamins C and E.

Millimolar concentrations of sodium ascorbate (vitamin C) induced apoptotic cell death in human promyelocytic leukemic HL-60 cells. The apoptotic cells displayed a smaller cell volume, disappearance of cell surface microvilli, appearance of cytoplasmic vacuoles, chromatin condensation, nuclear fragmentation and production of apoptotic bodies. The apoptosis-inducing activity of sodium ascorbate was significantly enhanced by noncytotoxic concentrations of CuCl2, but was almost completely eliminated by FeCl3. CuCl2 transiently stimulated the hydrogen peroxide (H2O2) production by sodium ascorbate, whereas FeCl3 slightly reduced the H2O2 production. alpha-Tocopherol (vitamin E) slightly enhanced the radical and H2O2 productions, and apoptosis induction by sodium ascorbate. The effect of alpha-tocopherol seems to be rather specific for ascorbic acid, since alpha-tocopherol did not significantly affect the cytotoxic activity of CuCl2, FeCl3 nor gallic acid. The present study demonstrated the cooperative action of vitamins C and E.

Antioxidants↗