LFG-500, a newly synthesized flavonoid, induced a reactive oxygen species-mitochondria-mediated apoptosis in hepatocarcinoma cells

LFG-500 is a newly synthesized flavonoid with a piperazine and a benzyl group substitution. Here we investigated the antitumor effect of LFG-500 in vivo and in vitro. Firstly, the apoptosis induced by LFG-500 in HepG2 cells was characterized by diamidino-phenyl-indole (DAPI) staining and Annexin V/PI double staining. The accumulation of reactive oxygen species (ROS) was also observed. Data suggested that LFG-500 could induce the generation of reactive oxygen species, which could be partly inhibited by NAC (N-acetylcysteine), an ROS inhibitor. LFG-500 also induced ROS accumulation followed by a decrease in mitochondrial membrane potential (MMP), and finally activated caspase cascade. Pretreatment with Z-VAD-FMK, a caspase inhibitor, could partly block the apoptosis induced by LFG-500. We also found that the expression of Bcl-2 protein was decreased whereas that of Bax protein was increased, leading to an increase in Bax/Bcl-2 ratio. Meanwhile, the translocation of apoptotic inducing factor (AIF) from cytosol to nuclei and the release of cytochrome c (Cyt c) from mitochondria were also detected, indicating that LFG-500 induced apoptosis through an ROS-mitochondrial-mediated pathway. The significant suppression of tumor growth was also observed in Heps-bearing mice. After treatment with 30mg/kg LFG-500, the inhibitory rate on tumor weight was 53.69%. Taken together, these results provided a mechanistic framework for further exploration of LFG-500 as a novel chemotherapy for human tumors.