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S Nagakura

Publications and source records attributed to S Nagakura.

42 records · Page 3Linked to original sources
PubMed1992

Altered expression of protein kinase C in adult T-cell leukemia cells.

Protein kinase C (PKC) has been shown to be involved in the mitogenic response and in oncogenic cell transformation in many experimental models. We analyzed the expression of PKC in both highly purified leukemic T cells freshly isolated from adult T-cell leukemia (ATL) patients and control T lymphocytes obtained from healthy volunteers. PKC activity was decreased in the ATL cells as compared with the control T cells. Cytosolic PKC activity in the ATL cells was remarkably decreased, whereas particulate membrane PKC activity was similar to the control level. The percentage of PKC activity in the particulate fraction was 34% in the ATL cells and 19% in the control cells. Regarding the altered subcellular localization of PKC activity, phorbol ester-induced translocation of cytosolic PKC was inhibited in some ATL cases. Similarly to the decrease in PKC activity, there was a decrease in the expression of the major PKC isozymes II(beta) and III(alpha) in ATL cells. These results suggest impaired regulation of PKC expression in ATL as well as in many experimental cancers.

Adult↗
PubMed1992

Common phenotypic expression of gangliosides GM3 and GD3 in normal human tissues and neoplastic skin lesions.

The expression of gangliosides in non-malignant tissues (epidermis and pigmented nevus) and neoplastic lesions (melanoma, squamous cell carcinoma [SCC] and basal cell carcinoma [BCS]) of the human skin was analyzed immunohistochemically and biochemically to characterize the features associated with malignancy. Immunohistochemical staining with an anti-II3NeuAc-LacCer (GM3) monoclonal antibody (M2590 mAb) and an anti-II3(NeuAc)2-LacCer (GD3) mAb (R24) showed the expression of the gangliosides GM3 and GD3 to vary among the different tissues. M2590 clearly stained epidermal keratinocytes and the tumor cells of BCC and SCC, and strongly stained melanocytes and melanoma cells. In contrast, R24 did not stain epidermal keratinocytes and only faintly stained SCC cells, while it clearly stained BCC cells, and intensely stained melanocytes and melanoma cells. GM3 showed a similar level of staining among the tissue specimens, while the level of GD3 staining was quite variable among the tumor specimens. Biochemical analysis by thin-layer chromatography (TLC) with resorcinol staining and TLC immunostaining with either M2590 or R24 showed both GM3 and GD3 to be commonly expressed by both the normal and malignant skin tissues, including SCC. There was no close correlation between the intensity of immunohistochemical staining and the biochemically detected amounts of these gangliosides. This may have been partly due to the so-called cryptic expression of cell membrane gangliosides. Our results thus suggest that analysis of the tumor-associated expression of gangliosides requires several methods, since the sensitivity of the methods used may have a considerable effect on the diagnostic value of gangliosides as skin cancer markers.

Biomarkers, Tumor↗
PubMed1991

Hemolysis of human erythrocytes is a new bioactivity of gangliosides.

Using sheep erythrocytes and liposomes, an inhibitory effect of gangliosides has been shown on the activation of the alternative pathway of complement. However, in studies using human erythrocytes, we found that gangliosides had hemolytic activity that was possibly mediated through activation of the alternative pathway. Pretreatment of human erythrocytes obtained from healthy volunteers or paroxysmal nocturnal hemoglobinuria (PNH) patients with a ganglioside mixture purified from human erythrocytes enhanced their susceptibility to homologous human complement, and resulted in dose-dependent hemolysis. The enhancement was more marked in PNH erythrocytes than control cells. Protease treatment of the ganglioside mixture did not change its hemolytic activity, but sialidase treatment abolished the activity. Among the major erythrocyte gangliosides, II3NeuAc-LacCer (GM3) was the most potent hemolytic agent. Gangliosides purified from bovine brain were also active, while neither nonsialylated glycosphingolipids, the ceramide moiety, or sialic acid alone were active. Sialic acid residues in the ganglioside molecules were essential to this activity, but the amount of the residue or the source of the gangliosides seemed not to be important. Several treatments inhibiting the alternative but not classical complement pathway markedly reduced the ganglioside hemolytic activity. This novel bioactivity of gangliosides was thus suggested to be mediated partly by activation of the alternative pathway.

Chromatography, Thin Layer↗
PubMed1990

Establishment and characterization of acute B-cell lymphocytic leukemia cell line showing (8;14) and (14;18) chromosome translocation.

Cell line KHM-2B expressing two oncogene products, c-myc and bcl-2, was established from a patient with acute lymphocytic leukemia with an 8;14 and 14;18 chromosome translocation. Surface marker studies of the cell line showed that the cells were positive for HLA-DR, CALLA (CD10), B1 (CD20) and B4 (CD19), but negative for T11 (CD2). The fresh cells from peripheral blood of the patient had no surface immunoglobulins, whereas KHM-2B cells were positive for mu.lambda type surface immunoglobulin. A cytogenetic analysis of the cell line revealed two translocations, t (8;14) (q24;q32) and t(14;18)(q32;q21). Rearrangement of the c-myc and bcl-2 genes was detected by Southern blot analysis of the KHM-2B DNA. Northern blot analysis revealed production of c-myc and bcl-2 mRNAs. These results indicated that two oncogenes were activated by two translocations to immunoglobulin genes.

Antigens, Surface↗
PubMedDate not supplied

Calcification in mucinous cholangiocellular carcinoma.

Calcification is rarely seen in cholangiocellular carcinoma. We herein report the case of a 53 year-old man with calcification in a cholangiocellular carcinoma. Because imaging studies had revealed coarse calcified foci, hepatolithiasis was suspected pre-operatively. The patient underwent a laparotomy in which intra-operative cholangioscopy revealed no gallstones but did reveal an unsuspected tumor with abundant mucin. A left hepatic lobectomy with resection of the extrahepatic bile duct was performed. The tumor histology was mucinous adenocarcinoma with calcification. In the English language literature, we found 9 cases of cholangiocellular carcinoma with macroscopic calcification. Six of these cases were mucinous adenocarcinomas. Roentgenologic examination revealed coarse calcification in 7 cases and fine calcification in 2 cases. Clinicians should note that cholangiocellular carcinoma, especially the mucinous variant, may be accompanied by coarse calcification.

Adenocarcinoma, Mucinous↗