Effect of retinoic acid and phorbol-12-myristate-13-acetate on glycosyltransferase activities in normal and transformed cells.

Retinoic acid was found to increase the activity of cytidine monophosphosialic acid:lactosylceramide sialyltransferase activity in a nontransformed clonal hamster cell line, NIL 8, and a virally transformed clone, NIL 8-HSV. The potent tumor promoter phorbol-12-myristate-13-acetate (PMA) had no significant effect on sialyltransferase activity in NIL 8 cells but stimulated this activity almost 6-fold when added to NIL 8-HSV cells. There was a synergistically additive effect on sialyltransferase activity when PMA was added to NIL 8 cells in concert with retinoic acid.

Rapid morphological and substratum adherence response by hairy cell and other human leukemic cells to phorbol ester tumor promoters.

Human leukemic cells, maintained in tissue culture, responded differentially following exposure to the phorbol ester tumor promoter 12-0-tetradecanoylphorbol-13-acetate (TPA). Short-term (0-2 h) TPA treatment of hairy cell leukemic cells (of presumed B-lymphocytic origin) resulted in the attachment of 5-100% of cells (depending on % leukemic mononuclear cells) to the culture dish and extension of long processes. Similar changes were also observed with cells from acute myelogenous, acute prolymphocytic and some acute monomyelocytic leukemic patients.

Phorbol ester tumor promoters specifically stimulate choline phospholipid metabolism in human leukemic cells.

Human hairy cell leukemia (HCL) cells in culture showed a marked increase in both [1-14C]acetate and [14C]choline incorporation into phosphatidylcholine (PC) when treated with a 10 nM concentration of 12-O-tetradecanoylphorbol 13-acetate (TPA) for 3 h. Dramatic morphological changes occurred and synthesis of most phospholipids was stimulated. However, the most dramatic increase was seen in the [14C]acetate labeling of both long- and short-chain fatty acid-containing sphingomyelins (from 200-425% of control levels), sphingomyelin being especially enriched in HCL cells.

Cell-cycle dependence of a ganglioside glycosyltransferase activity and its inhibition by enkephalin in a neurotumor cell line.

Rat glioma X mouse neuroblastoma hybrid neurotumor cells (NG108-15), synchronized by amino acid deprivation, showed a cell-cycle-dependent peak of activity of a ganglioside N-acetylgalactosaminyl transferase 14-24 h following release from the cell cycle block (S/G2 phase). Maximal expression of two typical lysosomal hydrolases, N-acetyl-beta-hexosaminidase and beta-galactosidase, occurred between 18 and 21 h following release (S phase), declining to G1 phase levels during the peak of N-acetylgalactosamine (GalNAc) transferase activity. In addition, glycosyltransferase activity in G2 phase cells showed an increase in apparent Vmax (suggesting the presence of more enzyme/mg of cell protein) and apparent binding affinity for uridine diphosphate N-acetylgalactosamine (UDP-GalNAc) (32 versus 14 microM) when compared to transferase activity in the G1 phase.

Cell cycle-dependent expression of specific opiate binding with variable coupling to adenylate cyclase in a neurotumor hybrid cell line NG108-15.

Monolayer cultures of neuroblastoma X glioma hybrid (clonal) cell line NG108-15, synchronized by the isoleucine/glutamine deprivation method, showed maximal expression of opiate binding sites at the same point in the cell cycle at which prostaglandin E1 (PGE1) had a maximum stimulatory effect on cyclic AMP synthesis. However, the capacity of enkephalin [D-Ala2D-Leu5] to block the stimulation of cyclic AMP synthesis by PGE1 was not related to the number of opiate receptors expressed. The Ki for the inhibition of cyclic AMP synthesis by opioid peptides increased substantially during the period of the cell cycle at which maximal expression of opiate binding sites occurred, making the effective level of inhibition of adenylate cyclase activity by 0.

Unique cell surface glycoprotein expression in hairy cell leukemia: effect of phorbol ester tumor promoters on surface glycoproteins, cell morphology, and adherence.

Hairy cell leukemia cells from eight different patients exhibited a characteristic cell surface glycoprotein pattern when labeled by the neuraminidase-galactose oxidase-NaB3H4 procedure. The diffuse high-molecular-weight glycoprotein band (Mr 230,000 to 300,000) was not seen in other leukemic cell types and may represent a specific hairy cell leukemia antigen. Hairy cell leukemia cells can be maintained as cell suspension cultures, but treatment with a variety of tumor-promoting phorbol esters caused the cells to adhere to plates, assume a fibroblastic elongated shape, and extend long processes.

Characterization of a glycosphingolipid beta-N-acetylgalactosaminyl-transferase activity in cultured hamster (nil) cells.

The activity of a glycosphingolipid N-acetylgalactosaminyltransferase (GalNAc transferase) in cultured hamster fibroblasts (NIL-8) was characterized with respect to substrate binding, acceptor specificity, pH optimum and detergent requirements. Of the glycosphingolipid acceptors tested, transferase activity was observed only with globotriaosylceramide. The apparent Km values for uridinediphosphate-N-acetylgalactosamine and globotriasylceramide were 0.