Induction of laryngeal cancer cell death by Ent-11-hydroxy-15-oxo-kaur-16-en-19-oic acid.

ABSTRACT

BACKGROUND: Ent-11-hydroxy-15-oxo-kaur-16-en-19-oic acid (5F) is known to exhibit antitumor activity, but its mechanism is not completely understood. 5F has not been tested in laryngeal cancer. METHODS: Two laryngeal cancer cell lines were treated with 5F. Cell death was analyzed by MTT [3-(4,5-dimethylthiozol-2-yl)-2,5-diphenyltetrazolium bromide] and Annexin V assay. Nuclear factor kappa beta (NF-κB)- and apoptosis-related molecules were examined. RESULTS: 5F induced laryngeal cancer cell death in a dose-dependent manner. The Annexin V assay and the measurement of cleavage of procaspase-3 and poly(ADP-ribose) polymerase demonstrated that the 5F-induced cell death was mainly apoptotic. 5F slightly reduced the basal level of NF-κB, but significantly suppressed the inducible NF-κB by reducing its transcriptional activity, protecting its inhibitory subunit IκBα from degradation, and suppressing its level in the nucleus. 5F also inhibited pro-proliferative and anti-apoptotic molecules but promoted pro-apoptotic Bax. CONCLUSIONS: 5F induces apoptosis of laryngeal cancer cells by inhibiting NF-κB activation/induction, suppressing pro-proliferative and anti-apoptotic molecules, and promoting pro-apoptotic Bax.