Cell Growth Inhibition and Down-Regulation of Survivin by Silibinin in a Laryngeal Squamous Cell Carcinoma Cell Line

Abstract

Objectives: Abnormalities in the regulation of apoptotic cell death have been shown to have an important effect on the pathogenesis and progression of cancer. Survivin, which is identified in most cancers and has recently been identified as an inhibitor of apoptosis, is a potential therapeutic target for cancer management. We investigated cell growth, apoptosis, and expression of survivin in laryngeal squamous cell carcinoma cell lines after treatment with the bioactive compound silibinin. Methods: Cultured human laryngeal squamous cell carcinoma SNU-46 cells were treated with different concentrations of silibinin, and the degree of cell growth and apoptosis was analyzed. Additionally, survivin protein and messenger RNA were analyzed by Western immunoblotting and reverse transcription–polymerase chain reaction. Results: Silibinin inhibited the growth of SNU-46 cells in a both dose- and time-dependent manner (p < 0.01). Upon fluorescence-activated cell sorter analysis, silibinin (200 μmol/L) treatment increased the proportion of apoptotic cells from 7% to 40%. At high concentrations (more than 150 μmol/L), silibinin greatly reduced messenger RNA and protein expression of survivin. Conclusions: Our findings demonstrate that silibinin induced apoptosis of laryngeal squamous carcinoma cells by a mechanism involving decreased survivin expression, which suggests the possibility that silibinin may be an effective treatment of laryngeal cancers.