Apoptotic effect of gambogic acid in esophageal squamous cell carcinoma cells via suppression of the NF-κB pathway

Despite extensive investigations of therapeutic improvements for surgical techniques, chemotherapy and chemoradiotherapy, esophageal squamous cell carcinoma (ESCC) remains one of the most aggressive forms of cancer, and the prognosis for patients with advanced ESCC remains poor. Therefore, effective therapies are urgently required in order to improve the prognosis of patients with ESCC. TE-1 cells were treated with gambogic acid (GA), and then subjected to western blot analysis, TUNEL assay and caspase activity analysis. GA significantly induced apoptosis in ESCC TE-1 cells. In addition, the antitumor activity of GA was accompanied by the decreased expression of phosphorylated-protein kinase B (p-AKT) and nuclear factor of κ light polypeptide gene enhancer in B-cells 1 (NF-κB). The inhibition of protein kinase B (AKT) and NF-κB activation by chemical inhibitors augmented the apoptotic effect responses to GA in the TE-1 cells. The pan-caspase inhibitor z-VAD-fmk (zVAD) decreased GA-induced apoptosis. Furthermore, zVAD attenuated GA-induced growth inhibition in TE-1 cells. GA induced apoptosis in ESCC TE-1 via suppression of NF-κB pathway. The findings of the present study may provide a novel insight into ESCC treatment.