LIMITED EXPOSURE OF CANCER CELL LINE HEPG2 TO MITOCHONDRIAL RESPIRATORY COMPLEX I INHIBITOR ROTENONE ENHANCES GLUTAMINE DEPRIVED CELL DEATH

Abstract

Cancer cells display enhanced utilisation of nutrients such as D-glucose (Glu) and L-glutamine (Q) for their growth. This high dependence of cancerous cells on nutrients has been widely utilised for developing anticancer strategies in different in vitro and in vivo models. In this study, we explored use of combination of low-dose mitochondrial complex I inhibitor, rotenone and extracellular glutamine deprivation as an antitumor approach in HepG2, an in vitro cellular model for studying human hepatocellular cancer. We found that exposure of HepG2 cells to low-dose of rotenone or to glutamine deprivation alone for 24 h resulted in non significant and less significant reduction in cell viability respectively. However, highly significant reduction in cell proliferation was observed on their combined treatment for 24 h as detected by MTT assay and morphological examination. Further investigation revealed involvement of generation of oxidative stress condition due to excess production of reactive oxygen species (ROS) and mitochondrial dysfunction as a result of mitochondrial membrane potential (Δѱm ) loss, in inhibitory proliferation due to this combined treatment as confirmed by fluorescent probes based flow cytometric assays. This study thus gives an insight into a new combinatorial strategy to better control growth of human hepatocellular carcinoma in vitro by utilising their dependency on extracellular glutamine.