Discovery and Optimization of 7-Alkylidenyltetrahydroindazole-Based Acylsulfonamide EP3 Antagonists

A novel series of 7-alkylidenyltetrahydroindazole-based acylsulfonamides were discovered as potent EP3 antagonists. The initial lead compound 7 exhibited potent in vitro EP3 inhibitory activity and good selectivity against other EP receptors. In addition, compound 7 demonstrated in vivo activity in a rat ivGTT model, reversing the suppressive effect of the EP3-specific agonist sulprostone on glucose-stimulated insulin secretion. Further optimization to improve the pharmacokinetic profile led to the discovery of compounds 26 and 28 with potent in vitro activity and significantly lower in vivo clearance and higher oral exposure than compound 7.

Development of an in vivo active, dual EP1 and EP3 selective antagonist based on a novel acyl sulfonamide bioisostere

Recent preclinical studies demonstrate a role for the prostaglandin E(2) (PGE(2)) subtype 1 (EP1) receptor in mediating, at least in part, the pathophysiology of hypertension and diabetes mellitus. A series of amide and N-acylsulfonamide analogs of a previously described picolinic acid-based human EP1 receptor antagonist (7) were prepared. Each analog had improved selectivity at the mouse EP1 receptor over the mouse thromboxane receptor (TP). A subset of analogs gained affinity for the mouse PGE(2) subtype 3 (EP3) receptor, another potential therapeutic target. One analog (17) possessed equal selectivity for EP1 and EP3, displayed a sufficient in vivo residence time in mice, and lacked the potential for acyl glucuronide formation common to compound 7. Treatment of mice with 17 significantly attenuated the vasopressor activity resulting from an acute infusion of EP1 and EP3 receptor agonists. Compound 17 represents a potentially novel therapeutic in the treatment of hypertension and diabetes mellitus.

Differential regulation of the aggressive phenotype of inflammatory breast cancer cells by prostanoid receptors EP3 and EP4

BACKGROUND

Although inflammatory breast cancer (IBC) is recognized as the most lethal variant of locally advanced breast cancer, few molecular signatures of IBC have been identified that can be used as targets to develop therapeutics that effectively inhibit the aggressive phenotype displayed by IBC tumors.

METHODS

Real-time polymerase chain reaction analysis, Western blot analysis, modified Boyden chamber invasion assays, vasculogenic mimicry (VM) assays, and gelatin zymography were used in the current studies. Agonists and antagonists of the prostanoid receptors EP3 and EP4 and of EP4 short-hairpin RNA (shRNA) knockdown approaches were used as tools to assess the role of prostanoid receptors EP3 and EP4 in the regulation of specific biologic activities of IBC cells.

RESULTS

The current studies revealed that the IBC breast cancer cell lines SUM149 and SUM190 express high levels of cyclooxygenase-2 messenger RNA and protein, produce abundant levels of prostaglandin E(2), and produce both EP3 and EP4 receptor proteins. Studies using the EP4 antagonist GW627368X and shRNA molecular knockdown approaches revealed a role for EP4 in regulating invasion of IBC cells. EP3, but not EP4, regulated the ability of SUM149 cells to undergo VM, which is the ability to form capillary-like structures, a characteristic exhibited by very aggressive tumor types. Inhibition of VM by sulprostone was associated with an inhibition of matrix metalloprotease-2 (MMP-2) enzyme activity.

CONCLUSIONS

The prostanoid receptors EP3 and EP4 differentially regulate activities exhibited by IBC cells that have been associated with the aggressive phenotype of this lethal variant of breast cancer. Whereas EP4 regulates invasion, EP3 regulates VM and the associated increased MMP-2 enzyme activity.