Ro 90-7501 is an amyloid β₄₂ (Aβ₄₂) fibril assembly inhibitor that reduces Aβ₄₂-induced cytotoxicity (EC₅₀ of 2 μM). Ro 90-7501 inhibits ATM phosphorylation and DNA repair. RO 90-7501 selectively enhances toll-like receptor 3 (TLR3) and RIG-I-like receptor (RLR) ligand-induced IFN-β gene expression and antiviral response^[2]. Ro 90-7501 also inhibits protein phosphatase 5 (PP5) in a TPR-dependent manner^[3]. Ro 90-7501 has significant radiosensitizing effects on cervical cancer cells^[4]. In Vitro: Ro 90-7501 significantly enhances radiosensitivity compared with control HeLa and ME-180 cells. Ro 90-7501 significantly increases apoptosis and impaired cell cycle after irradiation. Ro 90-7501 suppresses the phosphorylation of ATM and its downstream proteins, such as H2AX, Chk1, and Chk2, after irradiation^[1].
RO 90-7501, itself affects neither IFN-β nor NFκB promoter activity, but significantly enhances poly I:C-induced IFN-β promoter activation and inhibits the activation of NFκB in a dose-dependent manner. Treatment of cells with RO 90-7501 significantly enhances the antiviral activity of poly I:C^[2]. In Vivo: Ro 90-7501 (5 μg/g; intraperitoneal injection; daily; for 21 days; female BALB/c nude mice) treatment significantly delays tumor growth and significantly decreases tumor volume^[1].