Knockdown of sensitive to apoptosis gene by small interfering RNA enhances the sensitivity of PC3 cells toward actinomycin D and etoposide.

Actinomycin D and etoposide induce the production of reactive oxygen species, which play an important causative role in apoptotic cell death. Sensitive to apoptosis gene (SAG) protein, a redox inducible zinc RING finger protein that protects mammalian cells from apoptosis by redox reagents, is a metal chelator and a potential reactive oxygen species scavenger. The present report show that knockdown of SAG expression in PC3 cells greatly enhances apoptosis induced by actinomycin D and etoposide. Transfection of human prostate cancer PC3 cells with SAG small interfering RNA (siRNA) markedly decreased the expression of SAG, enhancing the susceptibility of actinomycin D- and etoposide-induced apoptosis reflected by DNA fragmentation, cellular redox status and the modulation of apoptotic marker proteins. These results indicate that SAG may play an important role in regulating the apoptosis induced by actinomycin D and etoposide and the sensitizing effect of SAG siRNA on the apoptotic cell death of PC3 cells offers the possibility of developing a modifier of cancer chemotherapy.