ABSTRACT

Sphingolipids regulate multiple cellular processes, including proliferation, autophagy, and apoptosis. Sphingosine kinases, the key enzymes in the metabolism of sphingolipids, are overexpressed in many cancers, making them important targets for the development of antitumor drugs. ABC294640 is a selective sphingosine kinase 2 (SK2) inhibitor that shows good antitumor activity in vitro. One phase I clinical study of ABC294640 reported that ABC294640 caused a variety of neurological disorders. The mechanism of these phenomena, however, remains unclear. In the present study, we used in vitro cell experiments to test the effects of ABC294640 on the nervous system. We found that ABC294640 suppressed the firing of action potentials in cultured hippocampal neurons from neonatal mice and inhibited endogenous sodium, potassium, and calcium currents in both cultured neurons and SH-SY5Y cells. In addition, we tested four types of human voltage-gated potassium channels transiently expressed in HEK293T cells. All were inhibited by ABC294640, of which K_V4.2 and K_V1.4 were more sensitive than BK and K2P2.1. The effect of ABC294640 on ion channels was different from another SK2 inhibitor K145 and was not affected by S1P. The fast onset and recovery of the inhibition indicated that ABC294640 was likely to inhibit ion channels by acting directly on channel proteins, rather than by inhibiting SK2. These results revealed the mechanism by which ABC294640 interferes with the nervous system. To develop future antitumor drugs, researchers should modify the structure of ABC294640 to avoid its effects on ion channels or should develop compounds that target SK2 or downstream molecules.

摘要

鞘脂调节多种细胞过程，包括增殖，自噬和凋亡。鞘氨醇激酶是鞘氨醇代谢中的关键酶，在许多癌症中都过表达，使其成为开发抗肿瘤药物的重要靶标。ABC294640是一种选择性鞘氨醇激酶2（SK2）抑制剂，在体外显示出良好的抗肿瘤活性。ABC294640的一项I期临床研究报告说ABC294640引起了多种神经系统疾病。但是，这些现象的机理尚不清楚。在本研究中，我们使用体外细胞实验来测试ABC294640对神经系统的影响。我们发现ABC294640抑制了新生小鼠培养的海马神经元动作电位的激发，并抑制了内源性钠，钾，和神经细胞和SH-SY5Y细胞中的钙电流。此外，我们测试了HEK293T细胞中瞬时表达的四种类型的人类电压门控钾通道。所有这些都被ABC294640抑制，其中K_V 4.2和K _V 1.4比BK和K2P2.1更敏感。ABC294640对离子通道的作用不同于另一种SK2抑制剂K145，并且不受S1P影响。抑制作用的快速发生和恢复表明ABC294640可能通过直接作用于通道蛋白而不是抑制SK2来抑制离子通道。这些结果揭示了ABC294640干扰神经系统的机制。为了开发未来的抗肿瘤药物，研究人员应该修改ABC294640的结构，以避免其对离子通道的影响，或者应该开发针对SK2或下游分子的化合物。