Acyl-CoA synthetase ACSVL3 in Malignant Glioma: Metabolism and Oncogenic Cellular

恶性胶质瘤占脑肿瘤的很大比例。由于这些肿瘤通常是难治性的， 对于治疗，需要新的和新颖的治疗方法。ACSVL 3是一种脂肪酶， 酸（FA）代谢，被发现在人类恶性胶质瘤中高度上调，并由 致癌受体酪氨酸激酶（RTK）信号在培养的神经胶质瘤细胞。ACSVL 3是26种酰基辅酶A之一， 合成酶（ACS），其“激活”FA以参与生物合成、降解和调节 下游代谢途径。快速肿瘤生长需要高速率的膜脂质合成;这些 脂质在致癌细胞质信号传导中也具有关键功能。使用完善的临床前模型， 在人胶质瘤中，我们发现使用RNA干扰的ACSVL 3敲低（KD）降低了体外表达。 人胶质瘤细胞的恶性表型。我们建立了ACSVL 3表达与 体内胶质瘤异种移植物中的肿瘤发生。我们进一步建立了ACSVL 3表达与 以及通过磷脂酰肌醇-3激酶（PI 3 K）/Akt的致癌第二信使信号传导， 磷脂酶c-<$（PLC-<$）/二酰基甘油（DAG）途径。我们假设ACSVL 3产生特定的 通过（i）产生特定结构脂质（ii）改变脂质 直接参与细胞信号传导，或（iii）改变参与膜与特异性 致癌信号蛋白。基于我们的初步发现，我们还假设靶向ACSVL 3 将对恶性胶质瘤的治疗有价值，并提出以下具体目的：（1） 鉴定ACSVL 3缺失对人神经胶质瘤细胞系体外表型的影响，（2） 确定ACSVL 3缺失对恶性胶质瘤细胞脂质代谢的影响，（3）阐明 ACSVL 3 KD如何改变恶性胶质瘤细胞中的信号转导，以及（4）确定ACSVL 3 KD如何改变恶性胶质瘤细胞中的信号转导。 耗尽抑制神经胶质瘤致瘤性。在目标1中，我们将研究细胞增殖、凋亡和自噬 在对照和KD人神经胶质瘤细胞中测定ACSVL 3在肿瘤发生中的特异性。这些研究 还将扩展到其他胶质瘤模型，这些模型可能在随后的目标中证明是有用的，例如细胞系， 内源性表达抑癌基因PTEN。ACSVL 3在脂质代谢中的功能尚不清楚 对正常细胞或癌细胞都是如此。目标2提出了填补这一知识空白的研究，也将识别脂质 与恶性表型相关的途径。在目标3中，详细分析了PI 3 K/Akt和PLC-1/Akt。 将在对照和ACSVL 3 KD神经胶质瘤细胞中进行DAG信号传导途径。目标4： 将探索ACSVL 3 KD对体内肿瘤发生、脂质代谢改变和RTK信号传导的影响， 在皮下和颅内异种移植物中。这些研究的结果将建立机械基础 对于胶质瘤中ACSVL 3的上调，确定该酶在致癌RTK信号传导和脂质过氧化中的作用。 代谢，并验证在恶性胶质瘤中靶向该蛋白的治疗潜力。

Malignant glioma accounts for a significant percentage of brain tumors. As these tumors are typically refractory to treatment, there is a need for new and novel therapeutic approaches. Levels of ACSVL3, an enzyme of fatty acid (FA) metabolism, were found to be highly upregulated in human malignant gliomas and were induced by oncogenic receptor tyrosine kinase (RTK) signaling in cultured glioma cells. ACSVL3 is one of 26 acyl-CoA synthetases (ACS) that "activate" FAs for their participation in biosynthetic, degradative, and regulatory downstream metabolic pathways. Rapid tumor growth requires high rates of membrane lipid synthesis; these lipids also have key functions in oncogenic cytoplasmic signaling. Using a well-established preclinical model of human glioma, we found that ACSVL3 knockdown (KD) using RNA interference decreased the in vitro malignant phenotype of human glioma cells. We established a correlation between ACSVL3 expression and tumorigenesis in glioma xenografts in vivo. We further established a relationship between ACSVL3 expression and oncogenic second messenger signaling via the phosphatidyl inositol-3 kinase (PI3K)/Akt and phospholipase c-¿ (PLC-¿)/diacylglycerol (DAG) pathways. We hypothesize that ACSVL3 generates specific FA-CoA products that influence oncogenesis by (i) generating specific structural lipids (ii) altering lipids involved directly in cell signaling, or (iii) altering lipids involved in membrane interactions with specific oncogenic signaling proteins. Based on our preliminary findings, we also hypothesize that targeting ACSVL3 will be of therapeutic value in treating malignant glioma, and propose the following Specific Aims: (1) To identify the consequences of ACSVL3 depletion on the in vitro phenotype of human glioma cell lines, (2) To identify the consequences of ACSVL3 depletion on lipid metabolism in malignant glioma cells, (3) To elucidate how ACSVL3 KD alters signal transduction in malignant glioma cells, and (4) To determine how ACSVL3 depletion inhibits glioma tumorigenicity. In Aim 1 we will investigate cell proliferation, apoptosis, and autophagy in control and KD human glioma cells to determine the specificity for ACSVL3 in oncogenesis. These studies will also be extended to other glioma models that may prove useful in subsequent Aims, such as cell lines that endogenously express the tumor suppressor PTEN. The function of ACSVL3 in lipid metabolism is not known for either normal or cancer cells. Aim 2 proposes studies to fill this gap in knowledge that will also identify lipid pathways that correlate with the malignant phenotype. In Aim 3, detailed analyses of the PI3K/Akt and PLC-¿/ DAG signaling pathways in control and ACSVL3 KD glioma cells will be carried out. In Aim 4, effects of ACSVL3 KD on in vivo tumorigenesis, alterations in lipid metabolism, and RTK signaling will be explored, both in subcutaneous and in intracranial xenografts. The results of these studies will establish the mechanistic basis for ACSVL3 upregulation in glioma, pinpoint the role of this enzyme in oncogenic RTK signaling and lipid metabolism, and validate the therapeutic potential of targeting this protein in malignant glioma.