Silibinin induces growth inhibition and apoptotic cell death in human lung carcinoma cells.

BACKGROUND: The high systemic toxicity of chemotherapeutic agents limits their use to treat clinical lung cancer. These limitations could be minimized/overcome by using non-toxic phytochemicals, like, silibinin.
MATERIALS AND METHODS: We used small cell lung carcinoma cells (SCLC) SHP-77 and non-small cell lung carcinoma cells (NSCLC) A-549, analyzing cell growth inhibition and death with Trypan blue exclusion, indices of the cell cycle progression with flow cytometry and apoptosis with propidium iodide and Hoechst 33342.
RESULTS: Silibinin (25, 50 and 100 microM) treatment of SHP-77 and A-549 cells resulted in their growth inhibition and cell death. Cell cycle studies showed a small increase in G0-G1 population at all the time intervals in SHP-77 cells, however, in A-549 cells, a slight increase in G0-G1 but strong increase in S-phases was observed at lower treatment times, and a strong increase in G0-G1 population at 72 hours. Quantitative apoptotic studies showed that silibinin causes apoptotic cell death in both a dose- and a time-dependent manner with SHP-77 cells showing more apoptotic effect than A-549 cells.
CONCLUSION: Silibinin significantly induces growth inhibition, a moderate cell cycle arrest and a strong apoptotic death in both small cell and non-small cell human lung carcinoma cells, which warrants further studies to assess the efficacy of this non-toxic agent in animal lung tumor models.