Thioredoxin1 Inhibitor PX-12 Inhibits The Growth Of Hepatocellular Carcinoma And Enhances 5-FU Cytotoxicity

Objective 1-methylpropyl 2-imidazolyl disulfide (PX-12), a thioredoxin 1(Trxl) inhibitor, has been investigated in a number of cancers, but its effectiveness in the treatment of hepatocellular carcinoma (HCC) has not been reported. PX-12 has generated considerable interest in a variety of solid tumors, yet most studies have confined their interests to using PX-12 as a single agent. The aim of this study is to investigate whether PX-12 inhibits cell growth and has a synergistic anti-tumor effect in combination with 5-fluorouracil (5-FU) in HCC.Methods Cells were treated with different concentrations of PX-12 and 5-FU. Cell viability assays, colony formation assay, cell cycle assay, reactive oxygen species (ROS) assay, apoptosis analysis, western blot assay, immunohistochemistry and xenograft tumorigenicity assay were performed.Results Treatment with PX-12 inhibited cell growth, induced S-phase arrest, and increased ROS levels. PX-12-induced apoptosis and inhibition of colony formation were associated with the generation of reactive oxygen species (ROS), and inhibition of ROS attenuated PX-12-induced apoptosis and inhibition of colony formation. Treatment with PX-12 increased the expression of bax and reduced the expression of bcl-2, indicating that PX-12-mediated apoptosis is mitochondria-dependent. PX-12 also exerted a synergistic effect with 5-FU to significantly suppress tumorigenicity both in vitro and in vivo. Inhibition of ROS accumulation reduced the synergistic effect of PX-12 and 5-FU.Conclusions PX-12 has anti-tumor activity and a synergistic effect in combination with 5-FU in HCC. Treatment with PX-12 alone or in combination with 5-FU may have clinical use in the treatment of HCC and other cancers.