Medivir AB, Huddinge, Sweden.
J Biomed Sci. 2011 Oct 21;18(1):76. doi: 10.1186/1423-0127-18-76.
Accumulation of amyloid β-peptide (Aβ) in the plaques is one of the major pathological features in Alzheimer's disease (AD). Sequential cleavage of amyloid precursor protein (APP) by β-site APP cleaving enzyme 1 (BACE-1) and γ-secretase results in the formation of Aβ peptides. Preventing Aβ formation is believed to attenuate AD progression and BACE-1 and γ-secretase are thus attractive targets for AD drug development.
Combining BACE-1 and γ-secretase inhibition on Aβ secretion from human neuroblastoma SH-SY5Y cells was evaluated in this study. Secreted Aβ40 and Aβ42 levels were measured from SH-SY5Y cells stably transfected with APPwt or APPswe genes. A selective BACE inhibitor and the γ-secretase inhibitor LY450139 (semagacestat) were used to inhibit respective secretase.
LY450139 increased Aβ40 and Aβ42 secretion from SH-SY5Y APPwt cells at low concentrations (by 60% at 3 nM) followed by subsequent inhibition at higher concentrations (IC(50) 90 nM). Washout studies showed that the Aβ increase evoked by 3 nM LY450139 was not due to enhanced cleavage following substrate accumulation but rather to activation of Aβ formation. By contrast, LY450139 inhibited Aβ formation from SH-SY5Y APPswe in a monophasic manner (IC(50) 18 nM). The BACE inhibitor per se inhibited Aβ secretion from both SH-SY5Y APPwt and SH-SY5Y APPswe cells with IC(50)s ranging between 7 - 18 nM and also prevented the increased Aβ secretion evoked by 3 nM LY450139. Combining the BACE inhibitor with higher inhibitory concentrations of LY450139 failed to demonstrate any clear additive or synergistic effects.
BACE-1 inhibition attenuates the Aβ increase evoked by LY450139 while not providing any obvious synergistic effects on LY450139-mediated inhibition.
淀粉样β肽（Aβ）在斑块中的积累是阿尔茨海默病（AD）的主要病理特征之一。淀粉样前体蛋白（APP）通过β位 APP 切割酶 1（BACE-1）和 γ-分泌酶的连续切割，导致 Aβ肽的形成。抑制 Aβ的形成被认为可以减轻 AD 的进展，因此 BACE-1 和 γ-分泌酶是 AD 药物开发的有吸引力的靶点。
本研究评估了 BACE-1 和 γ-分泌酶联合抑制对人神经母细胞瘤 SH-SY5Y 细胞中 Aβ分泌的影响。从稳定转染 APPwt 或 APPswe 基因的 SH-SY5Y 细胞中测量分泌的 Aβ40 和 Aβ42 水平。使用选择性 BACE 抑制剂和 γ-分泌酶抑制剂 LY450139（semagacestat）分别抑制各自的酶。
LY450139 在低浓度（3 nM 时增加 60%）下增加 SH-SY5Y APPwt 细胞中 Aβ40 和 Aβ42 的分泌，随后在较高浓度下（IC50 为 90 nM）抑制。洗脱研究表明，3 nM LY450139 引起的 Aβ 增加不是由于底物积累后的增强切割，而是由于 Aβ 形成的激活。相比之下，LY450139 以单相方式抑制 SH-SY5Y APPswe 中的 Aβ形成（IC50 为 18 nM）。BACE 抑制剂本身以 7-18 nM 之间的 IC50 范围抑制来自 SH-SY5Y APPwt 和 SH-SY5Y APPswe 细胞的 Aβ 分泌，并防止 3 nM LY450139 引起的 Aβ 分泌增加。将 BACE 抑制剂与 LY450139 的更高抑制浓度联合使用未能显示出任何明显的相加或协同作用。
BACE-1 抑制减弱了 LY450139 引起的 Aβ 增加，而对 LY450139 介导的抑制没有提供任何明显的协同作用。
