title: Tumor-promoting phorbol ester induces alterations of sialidase and sialyltransferase activities of JB6 cells.
abstract: Sialidase and sialyltransferase activities were studied in JB6 mouse epidermal cells before and after exposure to phorbol ester, 12-O-tetradecanoyl phorbol-13-acetate (TPA), which irreversibly induces anchorage-independent growth and tumorigenicity. JB6 cells exhibited sialidase activities toward 4-methylumbelliferyl-alpha-D-N-acetylneuraminic acid (4MU-NeuAc) and gangliosides at pH 4.5 in the particulate fraction but apparently not in the cytosol at pH 4.5 or 6.0. In JB6 cells exposed to TPA and in the anchorage-independent transformants, the sialidase activity toward 4MU-NeuAc was decreased and the activity toward gangliosides was increased compared with those in untreated JB6 cells. Immunological analysis with antisera against membrane-associated sialidases I and II revealed that plasma membrane-associated sialidase I was increased and lysosomal membrane-associated sialidase II was decreased under these conditions. TPA treatment also affected the sialyltransferase activities of JB6 cells: and elevation of the transfer activities toward asialo-orosomucoid and asialo-porcine submaxillary mucin but a reduction of GM3 and GD3 synthase activities were observed on exposure to TPA and in cells transformed by TPA to retain anchorage-independency. These results suggest that an increase in sialic acid bound to glycoproteins and a decrease in that bound to glycolipids may occur in JB6 cells exposed to TPA and in the anchorage-independent transformants.
authors: Laboratory of Biochemistry, Tohoku University, Sendai.
authors: T
authors: T
authors: Miyagi
authors: J
authors: J
authors: Sagawa
authors: T
authors: T
authors: Kuroki
authors: Y
authors: Y
authors: Matsuya
authors: S
authors: S
authors: Tsuiki
mesh_terms: D000818:Animals; D002460:Cell Line / Q000187:drug effects; D005732:Gangliosides / Q000378:metabolism; D006923:Hymecromone / Q000031:analogs & derivatives / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009439:Neuraminidase / Q000378:metabolism*; D011233:Precipitin Tests; D012799:Sialyltransferases / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
chemical_list: D005732:Gangliosides; D006923:Hymecromone; C021224:2'-(4-methylumbelliferyl)-alpha-D-N-acetylneuraminic acid; D012799:Sialyltransferases; D009439:Neuraminidase; D013755:Tetradecanoylphorbol Acetate