Phthalimide conjugations for the degradation of oncogenic PI3K.

PI3K/Akt/mTOR pathway is crucial for carcinogenesis and its inhibitors have made a great progress in cancer treatment. However, there is still a great developing space for PI3K inhibitors as the acquired drug resistance hindered their application in clinical. Proteolysis-targeting chimeras (PROTACs) with the potential to handle the challenges faced in drug development could be an alternative therapeutic strategy. Moreover, the past two years have witnessed remarkable advances in the development of phthalimide conjugation as a strategy for the degradation instead of inhibition of the targets, including BET family proteins, Sirtuin 2, CDK 9, Smad 3, and BCR-ABL proteins. Here, we designed and synthesized a series of potential small molecular PROTACs for the degradation of PI3K. Four compounds induced remarkable PI3K degradation and down-regulated the phosphorylation of Akt, S6K and GSK-3β in liver cancer cells HepG2. Furthermore, the representative compound D proved to inhibit tumor cells proliferation by the induction of autophagy instead of apoptosis or cell cycle arrest.