Design, Synthesis, and Biological Evaluation of Sulfonamide Methoxypyridine Derivatives as Novel PI3K/mTOR Dual Inhibitors

Phosphatidylinositol 3-kinase (PI3K) plays an important role in cell proliferation, survival, migration, and metabolism, and has become an effective target for cancer treatment. Meanwhile, inhibiting both PI3K and mammalian rapamycin receptor (mTOR) can simultaneously improve the efficiency of anti-tumor therapy. Herein, a series of 36 sulfonamide methoxypyridine derivatives with three different aromatic skeletons were synthesized as novel potent PI3K/mTOR dual inhibitors based on a scaffold hopping strategy. Enzyme inhibition assay and cell anti-proliferation assay were employed to assess all derivatives. Then, the effects of the most potent inhibitor on cell cycle and apoptosis were performed. Furthermore, the phosphorylation level of AKT, an important downstream effector of PI3K, was evaluated by Western blot assay. Finally, molecular docking was used to confirm the binding mode with PI3K alpha and mTOR. Among them, 22c with the quinoline core showed strong PI3K alpha kinase inhibitory activity (IC50 = 0.22 nM) and mTOR kinase inhibitory activity (IC50 = 23 nM). 22c also showed a strong proliferation inhibitory activity, both in MCF-7 cells (IC50 = 130 nM) and HCT-116 cells (IC50 = 20 nM). 22c could effectively cause cell cycle arrest in G0/G1 phase and induce apoptosis of HCT-116 cells. Western blot assay showed that 22c could decrease the phosphorylation of AKT at a low concentration. The results of the modeling docking study also confirmed the binding mode of 22c with PI3K alpha and mTOR. Hence, 22c is a promising PI3K/mTOR dual inhibitor, which is worthy of further research in the area.