Cytotoxic Effects Of Oxaloacetate On Hepatocarcinoma HepG2Cells And Up-regulation Of VEGF MRNA In HepG2Cells By Oxaloacetate

Oxaloacetatic acid (OAA) is one of the intermediates in the Krebscycle. In addition to participate in the metabolism of energy production,OAA may have other effects on the cell. We report in the present studythat OAA could have a cell type dependent cytotoxic effect on a humanhepatic carcinoma cell line HepG2through apoptosis and ROSaccumulation. OAA decreased the viability and colony formation ofHepG2cell and induced death of the cell. Pro-apoptotic protein Bax wasup-regulated and anti-apoptotic protein Bcl-2was down-regulated inOAA-treated HepG2cell indicating an apoptosis through the intrinsicpathway was involved in the death of the cell. The level of reactiveoxygen species (ROS) in the OAA-treated HepG2cells was increased.Anti-oxidant N-acetylcysteine (NAC) and glutathione (GSH) preventedthe viability of the cell induced by OAA from decrease but could notalleviate the enhanced level of apoptotic Bax/Bcl-2mRNA expressionratio, which suggests that the OAA-induced apoptosis of HepG2cell isnot driven by oxidative damage and at least two distinct mechanisms, onemediated by ROS and one involved apoptosis, lead to the cytotoxic effectof OAA on HepG2cells.In addition, OAA could upregulate VEGF mRNA throughERK/Hif-1α/VEGF pathway. When HepG2cells were treated with OAA,the VEGF mRNA in the cells was upregulated, the phosphorylation ofERK was enhanced and Hif-1α protein in the cells was stabilized. MEK1inhibitor PD98059inhibited the increased in the level of phosphorylationof ERK, Hif-1α protein and VEGF mRNA elicited by OAA in the cells.Because VEGF plays a crucial role in angiogenesis, we speculate thatOAA could promote angiogenesis through ERK/Hif-1α/VEGF pathway.