Effect of N,N,N-trimethylsphingosine on protein kinase-C activit

Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Nitrogen containing other than solely as a nitrogen in an...

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4352401, 4352402, A61K 3114

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053310144

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BRIEF SUMMARY
FIELD OF THE INVENTION

The invention relates to compounds with a profound effect on protein kinase-C activity and mammalian cell proliferation; and methods of using the same.


BACKGROUND OF THE INVENTION

Sphingosine (SPN) is a long chain unsaturated amino alcohol of the formula C.sub.18 H.sub.37 O.sub.2 N found in cell membranes and in high concentration in nervous tissue. Sphingosine and sphingoid base (a long chain aliphatic base comprising a 1,3-dihydroxy-2-amino group at a terminus and derivatives thereof) have been implicated as inhibitors of protein kinase-C (PK-C) and EGF receptor-associated tyrosine kinase (EGF-RK) (Hannun & Bell, Science, 235, 670, 1987; Hannun, JBC, 261, 12604, 1986; Kreutter et al., JBC, 262, 1632, 1987).
Protein kinase-C activity is related closely to cell growth and recent studies indicate that increased tumorigenicity is correlated with over expression of PK-C.sub..beta.1 and PK-C.sub..gamma. in some experimental tumors (Housey et al., Cell, 52, 343, 1988; Persons et al., Cell, 52, 447, 1988). A mutant PK-C.sub..alpha. induces highly malignant tumor cells with increased metastatic potential (Megidish & Mazurek, Nature, 324, 807, 1989). It would appear that aberrant expression of PK-C may relate to tumor progression.
Recent studies indicate that phospholipids, sphingolipids and metabolic products thereof have an important role in the modulation of transmembrane signaling through PK-C and other membrane-associated kinases, such as EGF receptor-associated tyrosine kinase (Hakomori, JBC, 265, 18713, 1990). For example, PK-C activity is promoted by diacyl glycerol and inhibited by sphingosine (Hannun & Bell, supra; Hannun & Bell, Science, 243, 500, 1989; Merrill & Stevens, Biochem. Biophys. Acta, 1010, 131, 1989).
Sphingosine did not inhibit PK-C in vitro or at concentrations below 100 .mu.M and did not exhibit a stereospecific effect on PK-C (Igarashi et al., Biochem., 28, 6796, 1989). Many of the studies described above employed sphingosine obtained from a commercial source (for example Sigma Chemical Company) and the preparations contained various impurities including 3-O-methylsphingosine, 5-O-methylsphingosine and N-methylsphingosine. The impurities are likely to result from the process of preparation, namely methanolysis of sphingomyelin or cerebroside. Furthermore, in the sphingosine backbone, the D-erythro configuration about the chiral carbons is often converted to the D-threo configuration.
Igarashi et al. (supra) found that the inhibitory effect of sphingosine on PK-C activity is due to: (1) the stereospecific configuration of C2 to C3 (D-erythro configuration required); (2) presence of a long-chain aliphatic group; and (3) perhaps most essential, a negative charge at the primary amino group at C2. If the amino group was N-acetylated, the PK-C inhibitory activity was abolished since the negative charge of an amino group was eliminated by acetylation. However if the anionic character of the amino group was enhanced by N-methylation, the stereospecific PK-C inhibitory activity was enhanced.
Interaction of leukocytes with activated platelets and endothelial cells is an initial step in inflammatory processes and is mediated in part by a family of adhesion molecules known as selectins. Selectins include MEL-14 in mouse and ELAM-1, LAM-1 and GMP-140 (CD62/PADGEM) in man. The selectins are characterized by a similar structural motif consisting of a lectin domain at the N-terminal region, followed by an epidermal growth factor sequence, a complement-regulatory domain, a transmembrane region and a C-terminal domain (Stoolman, Cell, 56, 907, 1989 and Osborn, Cell, 62, 3, 1990). Members of the selectin family bind carbohydrate ligands (see for example, Springer, Nature, 346, 425, 1990; Brandley et al., Cell 63, 861, 1990; Lowe et al., Cell, 63, 475, 1990; and Walz et al., Science, 250, 1132, 1990).
Based on inhibition studies using a variety of glycosphingolipid liposomes, the binding epitopes of both ELAM-1 and GMP-140 expressed on HL60 (a human promyelocytic cell line) cells

REFERENCES:
Hannun et al., Science, vol. 235 (1987) pp. 670-679.
Igarashi et al., J. Biol. Chem., vol. 265 (10) (1990) pp. 5385-5389.

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