Sun Peng, Xia Shuli, Lal Bachchu, Shi Xiaohai, Yang Kil Sung, Watkins Paul A, Laterra John
Hugo W, Moser Research Institute at Kennedy Krieger, Baltimore, MD, USA.
BMC Cancer. 2014 Jun 4;14:401. doi: 10.1186/1471-2407-14-401.
Targeting cell metabolism offers promising opportunities for the development of drugs to treat cancer. We previously found that the fatty acyl-CoA synthetase VL3 (ACSVL3) is elevated in malignant brain tumor tissues and involved in tumorigenesis. This study investigates the role of ACSVL3 in the maintenance of glioblastoma multiforme (GBM) stem cell self-renewal and the capacity of GBM stem cells to initiate tumor xenograft formation.
We examined ACSVL3 expression during differentiation of several GBM stem cell enriched neurosphere cultures. To study the function of ACSVL3, we performed loss-of-function by using small interfering RNAs to target ACSVL3 and examined stem cell marker expression, neurosphere formation and tumor initiation properties.
ACSVL3 expression levels were substantially increased in GBM stem cell enriched neurosphere cultures and decreased after differentiation of the neurospheres. Down-regulating ACSVL3 with small inhibiting RNAs decreased the expression of markers and regulators associated with stem cell self-renewal, including CD133, ALDH, Musashi-1 and Sox-2. ACSVL3 knockdown in neurosphere cells led to increased expression of differentiation markers GFAP and Tuj1. Furthermore, ACSVL3 knockdown reduced anchorage-independent neurosphere cell growth, neurosphere-forming capacity as well as self-renewal of these GBM stem cell enriched neurosphere cultures. In vivo studies revealed that ACSVL3 loss-of-function substantially inhibited the ability of neurosphere cells to propagate orthotopic tumor xenografts. A link between ACSVL3 and cancer stem cell phenotype was further established by the findings that ACSVL3 expression was regulated by receptor tyrosine kinase pathways that support GBM stem cell self-renewal and tumor initiation, including EGFR and HGF/c-Met pathways.
Our findings indicate that the lipid metabolism enzyme ACSVL3 is involved in GBM stem cell maintenance and the tumor-initiating capacity of GBM stem cell enriched-neurospheres in animals.
靶向细胞代谢为开发抗癌药物提供了广阔的机遇。我们之前发现，脂肪酰辅酶A合成酶VL3（ACSVL3）在恶性脑肿瘤组织中表达上调，并参与肿瘤发生。本研究旨在探讨ACSVL3在多形性胶质母细胞瘤（GBM）干细胞自我更新维持以及GBM干细胞启动肿瘤异种移植形成能力方面的作用。
我们检测了几种富含GBM干细胞的神经球培养物分化过程中ACSVL3的表达。为了研究ACSVL3的功能，我们使用小干扰RNA靶向ACSVL3进行功能缺失实验，并检测干细胞标志物表达、神经球形成及肿瘤起始特性。
在富含GBM干细胞的神经球培养物中，ACSVL3表达水平显著升高，神经球分化后其表达降低。用小干扰RNA下调ACSVL3可降低与干细胞自我更新相关的标志物和调节因子的表达，包括CD133、醛脱氢酶、神经细胞黏附分子-1和Sox-2。在神经球细胞中敲低ACSVL3导致分化标志物胶质纤维酸性蛋白（GFAP）和βⅢ微管蛋白（Tuj1）表达增加。此外，敲低ACSVL3可降低这些富含GBM干细胞的神经球培养物的非锚定依赖性神经球细胞生长、神经球形成能力以及自我更新能力。体内研究表明，ACSVL3功能缺失显著抑制神经球细胞原位肿瘤异种移植的增殖能力。支持GBM干细胞自我更新和肿瘤起始的受体酪氨酸激酶途径，包括表皮生长因子受体（EGFR）和肝细胞生长因子/c-Met途径，调节ACSVL3表达，这一发现进一步确立了ACSVL3与癌症干细胞表型之间的联系。
我们的研究结果表明，脂质代谢酶ACSVL3参与了GBM干细胞的维持以及动物体内富含GBM干细胞的神经球的肿瘤起始能力。
