ALDH5A1/miR-210 axis plays a key role in reprogramming cellular metabolism and has a significant correlation with glioblastoma patient survival.

backgroundGlioblastoma (GBM) is the most aggressive among the tumors of the central nervous system (CNS), and has a dismal prognosis. Altered metabolism, especially the increased rate of aerobic glycolysis promotes rapid proliferation of GBM cells. Here, we investigated the role of aldehyde dehydrogenase 5 family member A1 (ALDH5A1), a mitochondrial enzyme in the aspect of GBM metabolism. We also studied the regulatory mechanisms of altered ALDH5A1 expression in GBM. APPROACH AND

resultsWe show that ALDH5A1 is significantly downregulated in GBM patients in a grade dependent manner as compared to control brain and its low expression is associated with poor prognosis. It is significantly downregulated under hypoxia and is a direct target of the hypoxia induced microRNA: miR-210. Ectopic overexpression of ALDH5A1 in GBM cell lines U-87 MG and T98G markedly reduced their proliferation, 3D spheroid forming ability, and formation of reactive oxygen species (ROS). ALDH5A1 upregulation increased the oxygen consumption rate (OCR), and reduced the extracellular acidification rate (ECAR) of GBM cells while miR-210 overexpression showed the opposite. A significant downregulation in the transcript levels of LDHA, PDK1, and SLC2A1; coupled with lower glucose uptake and lactate production upon ALDH5A1 overexpression reveals that ALDH5A1 significantly reduces the glycolytic capacity of GBM cells. Total ATP generated in 24 h was more when miR-210 was overexpressed, while a slight decrease in ATP formation was observed upon ALDH5A1 upregulation. Interestingly, we also observed that ALDH5A1 expression is elevated and miR-210 levels are downregulated in IDH-mutant glioma as compared to its wild-type form.

conclusionOverall, our findings suggest that miR-210 mediated downregulation of ALDH5A1 plays a critical role in tumor metabolism and helps maintaining a high glycolytic phenotype in GBM.