Histamine H3 receptor antagonist OUP-186 attenuates the proliferation of cultured human breast cancer cell lines

Abstract

Histamine is involved in various physiological functions, including its neurotransmitter actions in the central nervous system and its action as a causative agent of inflammation, allergic reactions, and gastric acid secretions. Histamine expression and biosynthesis have been detected in breast cancer cells. It was recently suggested that the histamine H₃ receptor (H₃R) plays a role in the proliferation of breast cancer cells. We recently developed the non-imidazole H₃R antagonist OUP-186 which exhibited a potent and selective human H₃R antagonistic activity as well as no activity against the human histamine H₄ receptor (H₄R). In this study, we compared the effects of OUP-186 on the proliferation of estrogen receptor negative (ER-) breast cancer cells (MDA-MB-231) and ER+ breast cancer cells (MCF7) to the effects of clobenpropit (potent imidazole-containing H₃R antagonist). OUP-186 and clobenpropit suppressed the proliferation of breast cancer cells. The IC₅₀ values at 48 h for OUP-186 and clobenpropit were approximately 10 μM and 50 μM, respectively. Furthermore, OUP-186 potently induced cell death by activating caspase-3/7, whereas cell death was only slightly induced by clobenpropit. In addition, OUP-186 treatment blocked the proliferation increase triggered by 100 μM (R)-(-)-α-methylhistamine (H₃R agonist). The use of 4-methylhistamine (H₄R agonist) and JNJ10191584 (selective H₄R antagonist) did not affect breast cancer proliferation. These results indicate that OUP-186 potently suppresses proliferation and induces caspase-dependent apoptotic death in both ER+ and ER-breast cancer cells.

Keywords: Growth inhibition; Histamine H(3) receptor antagonist; Human breast cancer cells; OUP-186.