Acyl-CoA Synthetase VL3 Knockdown Inhibits Human Glioma Cell Proliferation and Tumorigenicity

Abstract

The contribution of lipid metabolic pathways to malignancy is poorly understood. Expression of the fatty acyl-CoA synthetase ACSVL3 was found to be markedly elevated in clinical malignant glioma specimens but nearly undetectable in normal glia. ACSVL3 levels correlated with the malignant behavior of human glioma cell lines and glioma cells propagated as xenografts. ACSVL3 expression was induced by the activation of oncogenic receptor tyrosine kinases (RTK) c-Met and epidermal growth factor receptor. Inhibiting c-Met activation with neutralizing anti-hepatocyte growth factor monoclonal antibodies reduced ACSVL3 expression concurrent with tumor growth inhibition in vivo. ACSVL3 expression knockdown using RNA interference, which decreased long-chain fatty acid activation, inhibited anchorage-dependent and anchorageindependent glioma cell growth by ∼70% and ∼90%, respectively. ACSVL3-depleted cells were less tumorigenic than control cells, and subcutaneous xenografts grew ∼60% slower than control tumors. Orthotopic xenografts produced by ACSVL3-depleted cells were 82% to 86% smaller than control xenografts. ACSVL3 knockdown disrupted Akt function as evidenced by RTK-induced transient decreases in total and phosphorylated Akt, as well as glycogen synthase kinase 3β, via a caspase-dependent mechanism. Expressing constitutively active myr-Akt rescued cells from the anchorage-dependent and anchorage-independent growth inhibitory effects of ACSVL3 depletion. These studies show that ACSVL3 maintains oncogenic properties of malignant glioma cells via a mechanism that involves, in part, the regulation of Akt function. [Cancer Res 2009;69(24):9175-82]

Lipid metabolism enzyme ACSVL3 supports glioblastoma stem cell maintenance and tumorigenicity

“…These siRNAs have previously been shown to inhibit ACSVL3 expression in adherent human GBM cells [14]. Quantitative RT-PCR (qRT-PCR) revealed that ACSVL3 si3 and ACSVL3 si4 inhibited ACSVL3 mRNA levels in GBM neurosphere cells by ∼60% and ∼55%, respectively (Figure 2A, P  < 0.01).…”

Measurement of precursor enrichment for calculating intramuscular triglyceride fractional synthetic rate

“…Theoretically, the true precursor for IM TG synthesis is fatty acyl-CoA ( 18 ). When fatty acids enter the intracellular pool, the fi rst step is to be converted to metabolically active fatty acyl-CoA, catalyzed by fatty acyl-CoA synthase and synthetase ( 19,20 ). Our recent results from a complementary experiment demonstrated that the transport of fatty acids into the IM compartment and their subsequent conversion to fatty acyl-CoA and fatty acyl-carnitine occurred very fast, with the peak enrichment within 2 min after a bolus palmitate tracer injection (unpublished data).…”

Acyl-CoA Metabolism and Partitioning

“…It is also present on the mitochondria of cultured neural cell lines and can activate both long-chain and very long-chain FAs (153). The expression of Fatp3 is high in lung tumors (154) and in malignant glioma compared to normal glia (157). Knockdown by RNAi in human glioma and lung cell lines diminishes long-chain FA activation and inhibits anchorage-dependent and independent cell growth and the growth of xenografts via diminished Akt phosphorylation (154, 157).…”