The mechanisms of malic enzyme 2 in the tumorigenesis of human gliomas.

The high level of resistance of glioblastoma multiforme (GBM) to currently used chemotherapies and other conventional therapies, its invasive characteristics and the presence of stem-like cells are the major factors that make the treatment of GBM difficult. Recent studies have demonstrated that the homeostasis of energy metabolism, glycolysis and mitochondrial oxidation of glucose are important for GBM cell growth and chemo-resistance. However, it is not clear which specific gene(s) are involved in the homeostasis of energy metabolism and invasiveness of GBM cells. We performed a preliminary analysis of data obtained from Gene Expression Omnibus profiles and determined that malic enzyme 2 (ME2) expression was positively associated with WHO grade in human primary gliomas. Hence, we evaluated the detailed working mechanisms of ME2 in human GBM cell processes, including proliferation, cell cycle, invasion, migration, ROS, and ATP production. Our data demonstrated that ME2 was involved in GBM growth, invasion and migration. ME2 has two cofactors, NAD+ or NADP+, which are used to produce NADH and NADPH for ATP production and ROS clearance, respectively. If the catalytic activity of ME2 is determined to be critical for its roles in GBM growth, invasion and migration, small molecule inhibitors of ME2 may be valuable drugs for GBM therapy. We hope that our current data provides a candidate treatment strategy for GBM.