Abstract
Nasopharyngeal carcinoma (NPC) is an unnoticeable malignant tumor with a high potential of lymphatic metastasis, and its prevalence is high in Asia. Ionizing radiation is the mainstay of treatment for patients with NPC without metastasis. However, patients with metastatic lesions require advanced treatments such as chemotherapy. The present study investigated the apoptotic effect of luteolin-7-O-glucoside on NPC cells and elucidated its underlying signaling mechanisms. The results revealed that luteolin-7-O-glucoside significantly reduced the proliferation of NPC cell lines (NPC-039 and NPC-BM). Flow cytometry and morphological analysis results demonstrated that luteolin-7-O-glucoside treatment induced S and G2 /M cell cycle arrest, chromatin condensation, and apoptosis. In addition, mitochondrial membrane potential was observed to be depolarized with an increasing concentration of luteolin-7-O-glucoside. Proteins involved in the extrinsic and intrinsic pathways of apoptosis, such as death receptor, caspase-3, caspase-8, caspase-9, and Bcl-2 family proteins (Bax, t-Bid, Bcl-2, and Bcl-xL), were downregulated and upregulated after treatment with luteolin-7-O-glucoside, respectively. Moreover, the addition of a PI3K/AKT inhibitor enhanced the activation of poly-ADP-ribose-polymerase (PARP) and attenuated cell viability, indicating that luteolin-7-O-glucoside induced apoptosis in NPC cells through the AKT signaling pathway. These results indicated that the apoptosis of NPC cells modulated by luteolin-7-O-glucoside may be preceded by mitochondrial depolarization, cell cycle arrest, extrinsic and intrinsic apoptosis pathway activation, and AKT signaling modulation. Thus, luteolin-7-O-glucoside can be a promising anticancer agent against human NPC.