Identification of novel STAT3 inhibitors bearing 2-acetyl-7-phenylamino benzofuran scaffold for antitumour study.

Signal transducer and activator of transcription 3 (STAT3) is identified as a promising target for multiple cancer therapy and attracts widespread concern. Herein, we reported the discovery of a series of 2-acetyl-7-phenylamino benzofuran derivatives as STAT3 inhibitors using scaffold fusion strategy. Further structure activity relationship study led to the discovery of compound C6, which displayed the most potent anti-proliferation activities against MDA-MB-468 cells (IC = 0.16 μM). Western blot assay demonstrated that C6 inhibited the activation of STAT3 (Tyr705) without influencing the phosphorylation of STAT1 (Tyr701). Further mechanistic studies indicated that C6 caused a notable G2/M cycle-arresting and early apoptosis in a concentration-dependent manner in MDA-MB-468 cells. Finally, molecular modelling study elucidated the binding mode of C6 in STAT3 SH2 domain.