Yi Qi Jie Du Decoction Inhibits Proliferation and Induces Apoptosis of Nasopharyngeal Carcinoma Stem Cells Through Mitochondrial Apoptosis Pathway

Objective: To assess the effects of Yi Qi Jie Du Decoction (YQJDD) on nasopharyngeal carcinoma stem cells (NPC-SCs) and investigate the underlying mechanism. Methods: NPC-SCs were collected in serum-free culture system and identified by the sphere formation assay. The effect of YQJDD on the proliferation of NPC-SCs was detected using the Cell Counting Kit-8 assay. The change of mitochondrial membrane potential (ΔΨm) in NPC-SCs following treatment with YQJDD was investigated by JC-1 staining. The levels of apoptosis- associated proteins were examined using western blot analysis. Results: YQJDD significantly inhibited the proliferation of NPC-SCs in dose- and time-dependent manners. JC-1 staining revealed that YQJDD lowered the ΔΨm of NPC-SCs in a time- dependent manner. After treatment with YQJDD, the expression of cleaved caspase-3, -7 and -9, cleaved poly-ADP ribose polymerase, P21 and P53 were increased, while the expression of Survivin in NPC-SCs was decreased. However, the expression of cleaved caspase-8 remained nearly unchanged. Conclusions: YQJDD inhibits the growth and induces apoptosis of NPC-SCs via an intrinsic apoptosis pathway. Keywords: Nasopharyngeal carcinoma (NPC) Yi Qi Jie Du Decoction (YQJDD) Apoptosis, Cancer stem cells, Mitochondrial apoptosis pathway