Over-expression of nm23-H1 in HeLa cells provides cells with higher resistance to oxidative stress possibly due to raising intracellular p53 and GPX1

Abstract

Aim: To determine whether the antitumor factor nm23 is related with antioxidation. Methods: Full-length human nm23-H1 was cloned into a mammalianexpressing vector and transiently introduced into HeLa cells. Results: A remarkably low level of reactive oxygen species (ROS) was detected in the cells overexpressing nm23-H1. 3-(4,5-Dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide and trypan blue assays found that the cells transfected with a nm23-H1-expressing plasmid had higher viability and stronger resistance to oxidative stress. Immunoprecipitation tests revealed that endogenous nm23-H1 formed a protein complex with p53. Furthermore, the intracellular levels of p53 and p53-regulated gene GPX1 were obviously increased in the cells overexpressing nm23-H1. The downregulation of p53 in the cells overexpressing nm23-H1 resulted in a higher cellular ROS level and lower cell viability. Conclusion: The findings suggest that nm23-H1 may act as a cellular protector against oxidative stress, possibly triggering the p53-related antioxidative pathway. © 2008 CPS and SIMM.