Beneficial Metabolic Consequences of Acyl‐CoA Synthetase ACSVL3 Knockout in Glioma Cells

Abstract

We previously reported that knockdown or knockout (KO) of the fatty acid metabolic enzyme Very Long Chain Acyl‐CoA Synthetase 3 (ACSVL3; SLC27A3) in glioblastoma cells was beneficial. KO U87 glioma cells grew at a slower rate, became adherence‐dependent, and produced fewer, slower‐growing subcutaneous and intracranial tumors when implanted in NOD‐SCID mice. To understand the mechanisms underlying these changes, we investigated several possibilities. We initially demonstrated that lack of ACSVL3 did not slow the synthesis of membrane phospholipids necessary for the rapid proliferation of tumor cells in culture. We then investigated the possibility that ACSVL3 KO affected either apoptosis or autophagy. However, no differences in these processes between control and KO U87 cells were found. We next looked at cell cycle, and found that KO produced significant changes. In non‐synchronized cells, control U87 cells were mainly in G0/G1, while ACSVL3 KO cells were mainly in S‐phase. Both control and KO cells synchronized by serum starvation started out mainly in G0/G1, but by 12 hours KO cells shifted significantly toward S‐phase. Identification of the cyclins and cyclin‐dependent kinases that may be involved is in progress. Proteomic and metabolomic profiling indicated that in addition to effects on lipid metabolism, ACSVL3 KO produced changes in glucose and energy metabolism. Although glucose transporters GLUT1 and GLUT3 protein levels were reduced by KO, cellular uptake of labeled 2‐deoxyglucose was unaffected. However, oxidation of glucose to CO2 was reduced 40% by ACSVL3 depletion, and the cellular glucose level was 25% higher in KO cells. Glycolytic enzymes were upregulated by KO, but metabolic intermediates were essentially unchanged. Interestingly, lactate production and the levels of both LDHA and LDHB were elevated by ACSVL3 KO, and pentose phosphate pathway activity was lower in KO cells. Citric acid cycle enzymes, electron transport chain complexes, and ATP synthase protein levels were all reduced by ACSVL3 depletion. Mitochondria had a more punctate morphology in U87 cells, but were more elongated in KO cells. In conclusion, depletion of ACSVL3 affects many metabolic processes not directly related to lipid metabolism in human glioblastoma cells.Support or Funding InformationKennedy Krieger Research Administration fundsThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.