Antitumor activity, optimum administration method and pharmacokinetics of 13,14-dihydro-15-deoxy-deoxy-Delta7 -prostaglandin A1 methyl ester (TEI-9826) integrated in lipid microspheres (Lipo TEI-9826).

13,14-Dihydro-15-deoxy-Delta7-prostaglandin A1 methyl ester (TEI-9826), an antitumor prostaglandin analog, is a candidate for clinical trial. In the present study, we examined its biological stability in vitro, antitumor activity in vitro and in vivo, and pharmacokinetics. Although TEI-9826 was rapidly hydrolyzed to the carboxylic acid form (TOK-4528), TOK-4528 as well as Delta12-prostaglandin J2 (PGJ2) were found to be stable in rat, mouse and human serum in vitro. TEI-9826 exhibited nearly identical or greater potential antitumor activity compared to Delta12-PGJ2 and Delta7-PGA1 in vitro against Colon26 tumor cells. Further evaluation of TEI-9826 using the 38 human cancer cell lines panel and COMPARE analysis suggested that its mode of action is quite different from other anticancer agents that are currently used. TEI-9826 was integrated into lipid microspheres (Lipo TEI-9826) for dosing. Growth inhibition by Lipo TEI-9826 against Colon26 tumor inoculated s.c. in mice depended on administration route, i.e. at 80 mg/kg, no growth suppressive effect was observed for daily bolus i.v., but significant growth suppressive effect was observed for daily i.p., daily s.c. every other day s.c. and 4 times a day continuous (5 min) i.v. These tumor growth-suppressive effects were cytostatic and the tumor started to regrow at the end or a few days after the end of administration. The pharmacokinetic study suggested that maintaining the blood level of TEI-9826 and/or TOK-4528 was essential for their antitumor effects. These results show that continuous i.v. infusion might be the most suitable administration method of Lipo TEI-9826 for clinical trial.

Antitumor activity of 13,14-dihydro-15-deoxy-delta7-prostaglandin-A1-methyl ester integrated into lipid microspheres against human ovarian carcinoma cells resistant to cisplatin in vivo.

One of the delta7-prostaglandin A1 derivatives with unique antitumor activities, 13,14-dihydro-15-deoxy-delta7-prostaglandin-A1-methyl ester, was integrated into lipid microspheres (Lipo-TEI9826) and examined for its antitumor effect in vitro and in vivo. The in vitro relative resistance of human ovarian cancer, A2780CP, to cisplatin (CDDP) and Lipo-TEI9826 was 27.3 and 2.0, respectively, compared with A2780, the parent cell line of A2780CP. In in vivo experiments, when A2780CP and the parent cell line A2780 were inoculated into nude mice, A2780CP grew two times more rapidly than did A2780. The growth of A2780CP tumor was not suppressed by CDDP, whereas that of the A2780 tumor was significantly suppressed. Nevertheless, the growth of both the A2780 and the A2780CP inoculated tumors was significantly inhibited by treatment with Lipo-TEI9826 at any time after the initial treatment, compared with the lipid microspheres only. These results show that Lipo-TEI9826 may be an effective antitumor agent and capable of overcoming CDDP resistance.

Selective coupling of prostaglandin E receptor EP3D to multiple G proteins depending on interaction of the carboxylic acid of agonist and arginine residue of seventh transmembrane domain.

Prostaglandin E receptor EP3D is coupled to stimulation and inhibition of adenylate cyclase and stimulation of phosphatidylinositol turnover. To examine the roles of the interaction of the carboxylic acid of an agonist and its putative binding site, the arginine residue in the seventh transmembrane domain of EP3D, in receptor-G protein coupling, we have mutated the arginine to the non-charged glutamine. TEI-3356, an EP3 agonist with a negatively charged the carboxylic acid, and TEI-4343, a non-charged methylester of TEI-3356, inhibited the forskolin-stimulated cAMP formation in the same concentration-dependent manner, but stimulation of basal cAMP formation and Ca2+ mobilization by TEI-4343 was much lower than that by TEI-3356. In the mutant receptor, both TEI-3356 and TEI-4343 showed the inhibition of forskolin-stimulated cAMP formation in the same profile, but did not stimulate basal cAMP formation or Ca2+ mobilization. These findings suggest that the interaction between the carboxylic acid of agonist and the arginine residue is important in signal transduction for adenylate cyclase stimulation and Ca2+ mobilization but not for adenylate cyclase inhibition.

TEI-3356, a highly selective agonist for the prostaglandin EP3 receptor.

Recently, we cloned cDNAs for the three mouse PGE receptor subtypes, EP1, EP2 and EP3, and the prostacyclin receptor, and established cells that stably express each receptor. We examined the selectivity of TEI-3356, an isocarbacyclin analogue, compared with other EP agonists, sulprostone and misoprostol, using Chinese hamster ovary cells expressing each cloned receptor. TEI-3356 selectively displaced the [3H]PGE2 binding to EP3-expressing cell membranes, but showed very low affinity for both EP1 and EP2. Although TEI-3356 is an isocarbacyclin analogue, it showed low affinity for the prostacyclin receptor. On the other hand, sulprostone strongly displaced the [3H]PGE2 binding to EP1 and EP3, but not to EP2. Misoprostol weakly bound to the three subtypes without selectivity. TEI-3356 decreased the forskolin-induced cAMP formation in a concentration-dependent manner in the EP3-expressing cells, the half-maximal concentration for the inhibition being similar to that of sulprostone but lower than that of PGE2. These results demonstrate that TEI-3356 is a potent and highly selective agonist for the EP3 receptor.

Suppression of IgE antibody response in mice by a naphthalene derivative, TEI-6472.

In the present report, we investigated suppressive effects of a naphthalene derivative, (7E)-N-(2-carboxyphenyl)-8-(2-naphthyl)-5,6-trans-5,6-methano-7- octenamide L-lysine salt (TEI-6472), on in vitro and in vivo antigen-specific IgE response. Anti-trinitrophenyl (TNP) IgE response induced in vitro in TNP-keyhole limpet hemocyanin (KLH)-primed murine spleen cells was suppressed by about 60% in the presence of 10(-6) M TEI-6472. On the other hand, anti-TNP IgG1 and IgM response were not significantly suppressed under the same conditions. Proliferative responses of BALB/c spleen cells stimulated by lipopolysaccharide, concanavalin A or allogeneic spleen cells were not inhibited by TEI-6472 at 10(-6)-10(-5) M. Interleukin 4 production from helper T-cell clone, D10.G4.1 was suppressed only slightly (less than 20%) at 10(-6) M TEI-6472. This compound was also effective in suppressing secondary anti-TNP IgE response in mice that were immunized twice with TNP-KLH and alum. When 10-20 mg/kg/day TEI-6472 was administered s.c. for 5 consecutive days starting from one day before the first and the second immunization, secondary anti-TNP IgE response was inhibited most strongly (40-45%). Anti-TNP IgG1 response was also inhibited but to a smaller extent (20-24%), while anti-TNP IgM response was suppressed only slightly (0-15%). These results suggest that, under appropriate conditions, TEI-6472 can suppress IgE responses more preferentially both in vitro and in vivo.

Naphthalene derivatives that selectively inhibit an antigen-specific IgE response in murine lymphocytes.

When the spleen cells from BALB/c mice that had been immunized twice with TNP-KLH were cultured with the same antigen, the synthesis of anti-TNP IgE as well as anti-TNP IgG was induced. We found that the addition of a naphthalene derivative, (E)-N-(2-methoxy-carbonylphenyl)-8-(2-naphthyl)-5,6-trans-5,6-meth ano-7- octenamide (TEI-1338) or methyl-6,7-dihydroxy-2-naphthylthioacetate (TEI-3332) to this lymphocyte culture system resulted in a marked suppression of anti-TNP IgE response without affecting the corresponding IgG production. These compounds are expected to be a prototype for the drug that can be used for the treatment of IgE-mediated allergic diseases.

Effects of a novel fatty acid derivative [(7E)-8-(2-naphthyl)-5,6-trans-5,6-methano-7-octenoic acid] on arachidonic acid metabolism in cultured cells.

The effects of a novel synthetic fatty acid derivative (TEI-8005:(7E)-8-(2-naphthyl)-5,6-trans-5, 6-methano-7-octenoic acid) on arachidonic acid metabolism in some cultured cells were studied. The compound significantly stimulated prostaglandin (especially prostacyclin) biosynthesis in cultured vascular cells and gastric mucosal epithelial cells, and inhibited lipoxygenase product formation in n-butyrate-treated mastocytoma. In aortic smooth muscle cells in which cyclooxygenase activity was reduced, it strongly stimulated prostaglandin formation in young cells with reduced cyclooxygenase activity but had less effect in aged cells. These result indicated that TEI-8005 enhanced prostaglandin formation in cells with either normal or reduced cyclooxygenase activity.