The salicylanilide derivatives inhibit signal transducer and activator of transcription 3 pathways in A549 lung cancer cells.

The signal transducer and activator of transcription 3 (STAT3) is constitutively activated in certain cancer cells. Therefore, blocking the aberrant activity of STAT3 in tumor cells is a validated therapeutic strategy. To discover novel inhibitors of STAT3 activity, we report the salicylanilide derivatives as a new small molecule inhibitor of the STAT3 signaling pathway. The N-(3-chloro-4-fluorophenyl)-2-hydroxy-4-(3-(piperidin-1-yl)propoxy) benzamide potently inhibited the activation and transcriptional function of STAT3. These studies further validate STAT3 as a drug discovery target and provide evidence that pharmacological agents that can selectively reduce the phospho-STAT3 levels in human cancer cells result in tumor apoptosis and growth inhibition.