A novel 11β-HSD1 inhibitor improves diabesity and osteoblast differentiation

Selective inhibitors of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) have considerable potential as treatment for osteoporosis as well as metabolic syndrome including type 2 diabetes mellitus. Here, we investigated the anti-diabetic, anti-adipogenic, and anti-osteoporotic activity of KR-67500, as a novel selective 11β-HSD1 inhibitor. Cellular 11β-HSD1 activity was tested based on a homogeneous time-resolved fluorescence method. Oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) levels were measured in diet-induced obese (DIO)-C57BL/6 mice administered KR-67500 (50  mg/kg per day, p.o.) for 28 days and, additionally, its anti-diabetic effect was evaluated by OGTT and ITT. The in vitro anti-adipogenic effect of KR-67500 was determined by Oil Red O Staining. The in vitro anti-osteoporotic activity of KR-67500 was evaluated using bone morphogenetic protein 2 (BMP2)-induced osteoblast differentiation and receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclast differentiation model systems. KR-67500 improved the in vivo glucose tolerance and insulin sensitivity in DIO-C57BL/6 mice. KR-67500 suppressed cortisone-induced differentiation of 3T3-L1 cells into adipocytes. KR-67500 enhanced BMP2-induced osteoblastogenesis in C2C12 cells and inhibited RANKL-induced osteoclastogenesis in mouse bone marrow-derived macrophages. KR-67500, a new selective 11β-HSD1 inhibitor, may provide a new therapeutic window in the prevention and/or treatment of type 2 diabetes, obesity, and/or osteoporosis.