Background: Selenocystine (SeC) is a nutritionally available selenoamino acid presenting novel anticancer potential against human cancers. However, neither the effects nor mechanism of SeC against choriocarcinoma growth has been clarified yet. This study investigated the anticancer effects and mechanism of SeC against JEG-3 human choriocarcinoma growth in vitro and in vivo.
Materials and methods: The in vitro anticancer efficiency was evaluated with cell viability, apoptosis, and oxidative stress. JEG-3 cell viability was determined with 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Cell cycle distribution and apoptosis were examined by flow cytometric analysis. Oxidative damage was detected with immunofluorescence and western blotting. The in vivo anticancer efficiency was evaluated in immunodeficient mouse model of choriocarcinoma. The mechanism was also investigated.
Results: SeC dose and time dependently inhibited the viability of JEG-3 cells in vitro. The result of flow cytometry (FCM) analysis showed that obvious S-phase arrest and cell apoptosis were initiated by SeC in JEG-3 cells, which was further convinced by the decreased levels of cyclin A, poly-ADP-ribose polymerase cleavage, and activation of caspase-3,-7, and-9. In addition, SeC resulted in significant generation of reactive oxygen species (ROS) and superoxide anion, followed by the activation of DNA damage. However, SeC-induced oxidative damage and apoptosis were effectively blocked after ROS inhibition. Further investigation indicated that SeC effectively suppressed JEG-3 choriocarcinoma tumor xenograft growth in vivo. The mechanism may be the induction of cell apoptosis and oxidative damage through inhibiting cell proliferation (Ki-67) and angiogenesis (CD-31).
Conclusions: Our findings supported that human choriocarcinoma growth could be inhibited by SeC in vitro and in vivo through triggering oxidative damage-mediated S-phase arrest and apoptosis. Thus, SeC may be promising in the treatment of human choriocarcinoma.
Keywords: Apoptosis; S-phase arrest; choriocarcinoma; reactive oxygen species; selenocystine.