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Biomedical subjects

S Akinaga

Publications and source records attributed to S Akinaga.

43 records · Page 3Linked to original sources
PubMed1991

Antitumor activity of UCN-01, a selective inhibitor of protein kinase C, in murine and human tumor models.

Antitumor activity of UCN-01 (7-hydroxy staurosporine), a selective inhibitor of Ca2+- and phospholipid-dependent protein kinase C, was examined in comparison with staurosporine, a nonselective inhibitor of protein kinases, on human and murine tumor cell lines which have some aberrations in cellular signal transduction. UCN-01 inhibited the growth of five tumor cell lines about 9 to 90 times less potently than staurosporine in vitro. UCN-01 showed an in vivo antitumor effect against three human tumor xenografts [epidermoid carcinoma A431 (c-erbB-1 overexpression), fibrosarcoma HT1080 (N-ras activation), and acute myeloid leukemia HL-60 (N-ras activation)], giving a minimum treated/control ratio of 0.40 (P less than 0.01), 0.17 (P less than 0.01), and 0.61 (P less than 0.05), respectively. UCN-01 also exhibited significant antitumor activity against two murine tumor models (fibrosarcoma, K-BALB and M-MSV-BALB), which activated the v-ras and v-mos oncogenes, showing a minimum treated/control ratio of 0.27 (P less than 0.01) and 0.21 (P less than 0.01). Staurosporine did not show significant antitumor activity against any of these five tumors. UCN-01 inhibited the down-modulation of epidermal growth factor receptor caused by phorbol 12-myristate 13-acetate in A431 cells at a near 50% inhibitory concentration for cell growth. These results imply that UCN-01 is a promising antitumor agent which has a novel mechanism(s) of action.

Alkaloids↗
PubMed1988

Determination of the calcium antagonist benidipine hydrochloride in plasma by sensitive radioimmunoassay.

A sensitive radioimmunoassay of the 1,4-dihydropyridine calcium channel blocker (+/-)-(R*)-2,6-dimethyl-4-(m-nitrophenyl)-1,4-dihydropyridine-3,5-dicarb oxylic acid (R*)-1-benzyl-3-piperidinyl ester, methyl ester hydrochloride (benidipine hydrochloride, KW-3049) has been developed. Antiserum against KW-3049 was produced in rabbits by immunization with an immunogen prepared by conjugating a derivative of KW-3049 to bovine serum albumin. This antiserum was found to specifically bind to [3H]-KW 3049, while the recognition to [3H]-nitrendipine, another well-known dihydropyridine calcium channel blocker, was less pronounced. With the antiserum, [3H]-KW-3049 and dextran coated charcoal, this radioimmunoassay could detect 39 approximately equal to 500 pg/tube of KW-3049 in a buffer system, and 156 to 5000 pg/ml of KW-3049 in plasma by using 0.5 ml of the plasma which was pretreated with MeOH for deproteinization and extracted with diethyl ether under alkaline condition. To assess the specificity of the radioimmunoassay, the inhibition of [3H]-KW-3049 binding to the antiserum by the presumable metabolites was examined. Though three of these presumable metabolites could slightly inhibit the binding of [3H]-KW-3049, they were not detected in rat and dog plasma at 0.5 h after oral administration of KW-3049. Plasma levels of KW-3049 in rats receiving a single oral dose (1 mg/kg) determined by the radioimmunoassay show good agreement with those obtained by gas chromotography.

Animals↗
PubMed1987

Characterization of receptors for human recombinant interferon-gamma in human cells.

Highly purified human recombinant interferon-gamma (ReIFN-gamma) was radioiodinated with 125I-Bolton-Hunter reagent and used to characterize the receptor for ReIFN-gamma. 125I ReIFN-gamma specifically and saturably bound four human cells tested, FL, WISH, Daudi, and HL-60, which were reported to have ReIFN-gamma binding sites. Scatchard analysis of the binding data of FL cells revealed the presence of 5200 binding sites per cell and a Kd value of 2.1 X 10(-10) M. Although the binding of 125I ReINF-gamma was inhibited by unlabelled natural IFN-gamma and ReIFN-gamma, it was not inhibited by unlabelled human ReIFN-alpha and ReIFN-beta, suggesting that receptors for (Re)IFN-gamma were different from those for IFN-alpha or IFN-beta. However, ReIFN-gamma displaced the binding of 125I ReIFN gamma 3 to 5 times more effectively than IFN-gamma. Internalization of 125I ReIFN-gamma bound to the cell surface receptor was observed at 37 degrees C. Pretreatment of FL cells with unlabeled ReIFN-gamma caused a concentration-dependent down-regulation in the ReIFN-gamma receptor, which was specific for IFN-gamma and reversible. From these studies, we concluded that although the ReIFN-gamma is not identical to putative IFN-gamma, the recombinant form binds to the same binding sites for IFN-gamma and does not bind to the binding sites for IFN-alpha or beta.

Binding, Competitive↗
PubMed1986

Generation of a new monoclonal antibody and its application for determination and purification of biologically active human gamma-interferon.

Three monoclonal antibodies (MAbs) were raised against recombinant human gamma-interferon (rHuIFN-gamma). They were specific for rHuIFN-gamma and recognized parts of the molecule other than both terminal regions. Among these MAbs, only KM48 has an ability to neutralize the antiviral activity of rHuIFN-gamma. Using KM48 in combination with polyclonal antibodies, we have developed a double-sandwich enzyme immunoassay (ELISA). This ELISA preferentially detects the biologically active form of rHuIFN-gamma, because after treatment with 1 N HCl or 0.2% SDS, or at 95 degrees C, the reactivity in the ELISA and the biological activity determined by cytopathic effect (CPE) assay decrease in parallel. In addition, the ELISA recognizes both natural and rHuIFN-gamma with almost the same sensitivity. Therefore, the ELISA is useful for detecting the biologically active conformation of rHuIFN-gamma, and possibly may be useful in both industrial production and clinical studies. rHuIFN-gamma molecules bind specifically to the immunoaffinity column using the MAb KM48 as ligands. After elution with 7 M Urea/1 M NaCl, the rHuIFN-gamma can be renatured in phosphate-buffered saline with high recovery. Thus, the column provides simple one-step purification of biologically active rHuIFN-gamma.

Animals↗
PubMed1986

Analysis of receptors, cell surface antigens, and proteins in human melanoma cell lines resistant to human recombinant beta- or gamma-interferon.

We studied the mechanisms of resistance to interferon (IFN) in two human melanoma cell lines, SK-MEL-28/beta cells resistant to human recombinant beta-interferon (ReIFN-beta) and SK-MEL-28/gamma cells resistant to human recombinant gamma-interferon (ReIFN-gamma). SK-MEL-28/beta cells were resistant to both ReIFN-beta and IFN-alpha, but not ReIFN-gamma or natural gamma-interferon (IFN-gamma), and SK-MEL-28/gamma cells were resistant to both ReIFN-gamma and IFN-gamma, but not ReIFN-beta or IFN-alpha. SK-MEL-28/s cells, sensitive to both ReIFN-beta and ReIFN-gamma, had receptors for ReIFN-beta and ReIFN-gamma. Furthermore ReIFN-beta and IFN-alpha shared the common receptors as judged by competition assays, while the receptors for ReIFN-gamma were independent in SK-MEL-28/s cells. The Kd values of binding of both IFNs to SK-MEL-28/beta or SK-MEL-28/gamma cells were essentially equivalent to those to SK-MEL-28/s cells. Both labeled IFNs were internalized rapidly into all cell lines at 37 degrees C. No significant difference in internalization was found between IFN-sensitive and -resistant cells. Each cell line expressed HLA-AB and Mr 97,000 protein antigens, the expressions of which were enhanced by ReIFN-beta and ReIFN-gamma. Partial resistance to the enhancement of both antigens by both IFNs was seen in the resistant cells. Finally ReIFN-gamma, but not ReIFN-beta, induced a Mr 56,000 protein in SK-MEL-28/s cells. This effect of ReIFN-gamma was also detected in SK-MEL-28/beta cells, but not SK-MEL-28/gamma cells. These results provide some information concerning the nature of IFN-resistant cells. The receptors had no significant correlation with the resistance, while the expression of HLA-AB or Mr 97,000 protein antigens or the induction of proteins had some correlation with the resistance.

Antigens, Neoplasm↗
PubMed1986

Different kinetics of antiviral and anticellular activities between human recombinant and natural interferon-gamma arising from different receptor-binding properties.

Human recombinant interferon-gamma (ReIFN-gamma) and human natural interferon-gamma (IFN-gamma) showed significant differences in antiviral and anticellular activities. Namely, ReIFN-gamma exhibited antiviral activity against Sindbis virus and anticellular activity against HeLa S3 cells at significantly lower concentrations as compared with IFN-gamma at short exposure times of between 1 and 4 hr. This difference of activities was explicable in terms of different binding activities of the two IFNs to the receptors. The binding of 125I-ReIFN-gamma to the receptors was competitively decreased in a dose dependent manner by unlabeled ReIFN-gamma, whereas the competition by unlabeled IFN-gamma was significantly weaker. The results of pretreatment of the cells with unlabeled ReIFN-gamma or IFN-gamma suggested that the binding of IFN-gamma to the receptors was slower than that of ReIFN-gamma. ReIFN-gamma and IFN-gamma exhibited greater colony formation-inhibitory activity against HeLa S3 cells, as compared with IFN-alpha or ReIFN-beta. ReIFN-gamma also inhibited DNA, RNA and protein syntheses of HeLa S3 cells more potently than ReIFN-beta. However, the 2'-5' oligoadenylate (2'-5' A) synthetase activity in ReIFN-gamma-treated cells was significantly lower than that in ReIFN-beta-treated cells, suggesting that 2'-5' A synthetase does not play a major role in the anticellular activity of ReIFN-gamma, at least against HeLa S3 cells.

2',5'-Oligoadenylate Synthetase↗