5-(4-amino-1-propan-2-yl-3-pyrazolo[3-4-d]pyrimidinyl)-1-3-benzoxazol-2-amine and Retinoblastoma

We and others have shown that aberrant activation of the mammalian target of rapamycin (mTOR) signalling is essential for retinoblastoma progression and has potential therapeutic value. TAK-228 is a potent inhibitor of mTOR1 and 2 with preclinical activity in a variety of cancers. In this study, we report that TAK-228 is a dual inhibitor of retinoblastoma and angiogenesis. TAK-228 inhibits growth and induces apoptosis in a panel of retinoblastoma cell lines, with IC50 at ~0.2 μM. Under the same experimental conditions, TAK-228 was less effective in inhibiting growth and survival in normal retinal and fibroblast cells than retinoblastoma cells. In addition, TAK-228 inhibited retinal endothelial cell capillary network formation, migration, growth and survival. We further demonstrate that TAK-228 inhibits retinoblastoma and retinal angiogenesis through inhibiting mTOR signalling. Rescue studies confirm that mTOR is the target of TAK-228 in both retinoblastoma and retinal endothelial cells. Finally, we confirm the inhibitory effects of TAK-228 on tumor and angiogenesis in retinoblastoma xenograft mouse model. Our findings provide a preclinical rationale to explore TAK-228 as a strategy to treat retinoblastoma and highlight the therapeutic value of targeting mTOR in retinoblastoma.

Topics: Angiogenesis Inhibitors; Animals; Antineoplastic Agents; Apoptosis; Benzoxazoles; Cell Line, Tumor; Humans; Inhibitory Concentration 50; Male; Mice; Mice, Inbred NOD; Mice, SCID; Neovascularization, Pathologic; Pyrimidines; Retinal Neoplasms; Retinoblastoma; Signal Transduction; TOR Serine-Threonine Kinases; Xenograft Model Antitumor Assays