LncRNA IDH1-AS1 links the functions of c-Myc and HIF1a via IDH1 to regulate the Warburg effect

The oncoprotein c-Myc plays an important role in regulating glycolysis under normoxia; yet, in cancer cells, HIF1a, which is essential for driving glycolysis under hypoxia, is often up-regulated even in the presence of oxygen. The relationship between these two m ajor regulators of the Warburg effect remains to be fully defined. Here we demonstrate that regulation of a long noncoding RNA (lncRNA), named IDH1-AS1, enables c-Myc to collaborate with HIF1a in activating the Warburg effect under normoxia. c-Myc transcriptionally repressed IDH1-AS1, which, upon expression, promoted homodimerization of IDH1 and thus enhanced its enzymatic activity. This resulted in increased a-KG and decreased ROS production and subsequent HIF1a down-regulation, leading to attenuation of glycolysis. Hence, c-Myc repression of IDH1-AS1 promotes activation of the Warburg effect by HIF1a. As such, IDH1-AS1 overexpression inhibited cell proliferation, whereas silencing of IDH1-AS1 promoted cell proliferation and cancer xenograft growth. Restoring IDH1-AS1 expression may therefore represent a potential metabolic approach for cancer treatment.