Ro 48-8071 fumarate is an inhibitor of OSC (Oxidosqualene cyclase) with IC₅₀ of appr 6.5 nM. IC50 & Target: IC50: appr 6.5 nM (Oxidosqualene cyclase)^[1] In Vitro: In HepG2 cells, Ro 48-8071 reduces cholesterol synthesis dose dependently with an IC₅₀ value of appr 1.5 nM^[1]. Ro 48-8071 (10 μM) significantly reduces the viability of PC-3 prostate cancer cells, but not normal prostate cells. Ro 48-8071 (10-30 μM) induces apoptosis of both LNCaP and C4-2 cell lines in a dose-dependent manner. And castration-resistant PC-3 and DU145 cells also demonstrate significant levels of apoptosis following 24-hour treatment with Ro 48-8071. Ro 48-8071 (10-25 μM) reduces AR protein expression in a dose-dependent manner. Ro 48-8071 (0.1-1 μM) increases ERβ protein expression dose-dependently in both hormone-dependent LNCaP and castration-resistant PC-3 cells^[2]. Using mammalian cells engineered to express human ERα or ERβ protein, together with an ER-responsive luciferase promoter, Ro 48-8071 dose-dependently inhibits 17β-estradiol (E2)-induced ERα responsive luciferase activity (IC₅₀, appr 10 µM), under conditions that are non-toxic to the cells^[3]. In Vivo: Ro 48-8071 lowers LDL-C maximally appr 60% at 150 μmol/kg per day, with no further reduction up to 300 μmol/kg per day, leaving HDL-C unchanged at all doses in hamsters. Ro 48-8071 (≥00 μmol/kg per day) increases the amount of MOS in liver of hamsters. Ro 48-8071 (300 μmol/kg per day) remarkedly and significantly reduces VLDL secretion of hamsters^[1]. Ro 48-8071 (5 or 20 mg/kg) significantly reduces in vivo tumor growth in mice, without weight loss of the mice. Furthermore, Ro 48-8071 at a concentration of 20 mg/kg, completely eradicates two of the 12 tumors being monitored in the mice in the timeframe tested^[2]. Ro 48-8071 (20 mg/day/kg body weight) leads to a rapid and sustained inhibition (>50%) of cholesterol synthesis in the whole small intestine of BALB/c mice. Sterol synthesis is also reduced in the large intestine and stomach^[4].