Department of Biochemistry and Molecular Biology Brody School of Medicine, East Carolina University, and the East Carolina Diabetes and Obesity Institute, Greenville, NC.
Department of Biochemistry and Molecular Biology Brody School of Medicine, East Carolina University, and the East Carolina Diabetes and Obesity Institute, Greenville, NC; Department of Pharmacology, Faculty of Veterinary Medicine, South Valley University, Qena, Egypt.
J Lipid Res. 2019 Sep;60(9):1590-1602. doi: 10.1194/jlr.RA119000251. Epub 2019 Jul 30.
The combination of daunorubicin (dnr) and cytarabine (Ara-C) is a cornerstone of treatment for acute myelogenous leukemia (AML); resistance to these drugs is a major cause of treatment failure. Ceramide, a sphingolipid (SL), plays a critical role in cancer cell apoptosis in response to chemotherapy. Here, we investigated the effects of chemotherapy selection pressure with Ara-C and dnr on SL composition and enzyme activity in the AML cell line HL-60. Resistant cells, those selected for growth in Ara-C- and dnr-containing medium (HL-60/Ara-C and HL-60/dnr, respectively), demonstrated upregulated expression and activity of glucosylceramide synthase, acid ceramidase (AC), and sphingosine kinase 1 (SPHK1); were more resistant to ceramide than parental cells; and displayed sensitivity to inhibitors of SL metabolism. Lipidomic analysis revealed a general ceramide deficit and a profound upswing in levels of sphingosine 1-phosphate (S1P) and ceramide 1-phosphate (C1P) in HL-60/dnr cells versus parental and HL-60/Ara-C cells. Both chemotherapy-selected cells also exhibited comprehensive upregulations in mitochondrial biogenesis consistent with heightened reliance on oxidative phosphorylation, a property that was partially reversed by exposure to AC and SPHK1 inhibitors and that supports a role for the phosphorylation system in resistance. In summary, dnr and Ara-C selection pressure induces acute reductions in ceramide levels and large increases in S1P and C1P, concomitant with cell resilience bolstered by enhanced mitochondrial remodeling. Thus, strategic control of ceramide metabolism and further research to define mitochondrial perturbations that accompany the drug-resistant phenotype offer new opportunities for developing therapies that regulate cancer growth.
柔红霉素（dnr）和阿糖胞苷（Ara-C）的联合是治疗急性髓系白血病（AML）的基础；对这些药物的耐药性是治疗失败的主要原因。神经酰胺是一种鞘脂（SL），在化疗诱导的癌细胞凋亡中发挥关键作用。在这里，我们研究了用 Ara-C 和 dnr 进行化疗选择压力对 AML 细胞系 HL-60 中 SL 组成和酶活性的影响。耐药细胞，即在含有 Ara-C 和 dnr 的培养基中选择生长的细胞（分别为 HL-60/Ara-C 和 HL-60/dnr），表现出葡萄糖神经酰胺合酶、酸性神经酰胺酶（AC）和鞘氨醇激酶 1（SPHK1）的上调表达和活性；比亲本细胞对神经酰胺的抗性更强；并对 SL 代谢抑制剂敏感。脂质组学分析显示，HL-60/dnr 细胞相对于亲本和 HL-60/Ara-C 细胞普遍存在神经酰胺缺乏，同时鞘氨醇 1-磷酸（S1P）和神经酰胺 1-磷酸（C1P）水平显著升高。两种化疗选择的细胞也表现出全面的线粒体生物发生上调，这与对氧化磷酸化的高度依赖一致，这种特性部分被 AC 和 SPHK1 抑制剂的暴露所逆转，并支持磷酸化系统在耐药性中的作用。总之，dnr 和 Ara-C 选择压力诱导神经酰胺水平的急性降低和 S1P 和 C1P 的大幅增加，同时细胞的弹性增强，这得益于增强的线粒体重塑。因此，战略性地控制神经酰胺代谢，并进一步研究定义伴随耐药表型的线粒体扰动，为开发调节癌症生长的治疗方法提供了新的机会。
