Hypoxia-induced elevated NDRG1 mediates apoptosis through reprograming mitochondrial fission in HCC

Abstract

Hypoxia, as a form of stress, plays a critical role in oncogenesis, including metabolic reprogramming. Mitochondrial, the centers of energy production, re-balance mitochondria dynamic to maintain cell survival during high levels of environmental stresses. NDRG1 is a hypoxia-inducible protein that is involved in various human cancers, including HCC. However, little is known about whether NDRG1 participants in the quality control of mitochondrial in times of stress. Here, we firstly showed that how NDRG1 exerted its role through mediating mitochondrial dynamic in HCC cells under hypoxia. Initially, we identified that NDRG1 expression varies with oxygen content. NDRG1 silencing notably induced cell apoptosis under hypoxia, while no obviously change of wildtype cells in hypoxia compared with that in normoxia. Further analysis revealed that NDRG1 silencing in HCC cells led to increase of pro apoptotic protein BAX and decrease in anti-apoptotic proteins Bcl-2 and Bclx, which meant mitochondrial damage were induced. In the analysis of mitochondria, we found that more released cytochrome c located in cytosolic with NDRG1 knockdown in hypoxia, which may be due to mitochondria division. And the following experiment proved that more fragmented mitochondria were presented in NDRG1 silencing cells, as well as destroyed mitochondrial membrane potential with evidence by JC-1 was verified. Moreover, these trends could be reversed by Mdivi1. Further research showed that NDRG1 silencing disrupt hypoxia-enhanced aerobic glycolysis through effectively decreased glucose uptake, lactate output and ECAR value. In sum, we provide the first direct evidence that NDRG1-driven change in mitochondrial dynamics and aerobic glycolysis maintain cells survival in HCC during hypoxia.

Keywords: Glycolysis; Hypoxia; Mitochondrial dynamics; NDRG1.