C188-9, a small-molecule STAT3 inhibitor, exerts an antitumor effect on head and neck squamous cell carcinoma.

Abnormal activation of signal transducer and activator of transcription 3 (STAT3) is complicated in the tumor progression of multiple cancers including human head and neck squamous cell carcinoma (HNSCC) and, therefore, serves as a potent therapeutic target. In this study, we identify that C188-9, a small-molecule STAT3 inhibitor, exhibits an antitumor effect on HNSCC in vitro. C188-9 significantly inhibits cell growth, arrests cell cycle at G0/G1 phase, and induces apoptosis in HNSCC. Besides, the capacities of migration and invasion of HNSCC cells are impaired with the exposure to C188-9. In addition, C188-9 treatment enhanced the chemosensitivity of HNSCC cellsin vitro. Moreover, C188-9 inactivates STAT3 by reducing its phosphorylation at Tyr705. Taken together, these results indicate that C188-9 could be a promising therapeutic strategy for patients suffered from HNSCC by suppressing the STAT3 pathway.