Center of Medical Genetics , Buddhist Tzu Chi General Hospital , Hualien 970 , Taiwan.
Department of Biotechnology , Chia-Nan University of Pharmacy and Science , Tainan 717 , Taiwan.
J Agric Food Chem. 2018 Jun 20;66(24):6083-6093. doi: 10.1021/acs.jafc.8b02559. Epub 2018 Jun 12.
Pinostrobin, a flavonoid phytochemical found in variety of plants, has been demonstrated to possess numerous bioactivities such as antioxidant, anti-inflammatory, anticancer, and neuroprotective properties. The aim of this study was to investigate the hypocholesterolemic effect of pinostrobin on the regulation of the gene expression of PCSK9 and its underlying mechanisms in hepatic cells. We found that pinostrobin (20 and 40 μM) significantly inhibited the PCSK9 promoter activity from 1.00 ± 0.16 (fold) to 0.85 ± 0.06 and 0.54 ± 0.05, respectively, as well as the suppression of PCSK9 mRNA expression from 1.00 ± 0.11 (fold) to 0.81 ± 0.07 and 0.58 ± 0.07, respectively, in HepG2 cells. Pinostrobin significantly reduced the mature form of the PCSK9 protein, inhibited the catalytic activity of PCSK9, and increased the protein level of LDLR and the LDL uptake activity in HepG2 cells. We further demonstrated that pinostrobin markedly increased the level of nuclear forkhead box O3a (FoxO3a) protein, enhanced FoxO3a/PCSK9 promoter complexes formation, and attenuated the promoter binding capacity of nuclear HNF-1α. The knockdown of FoxO3a in HepG2 cells by small interference RNA (siRNA) abolished the pinostrobin-mediated PCSK9 reduction. Finally, we demonstrated that pinostrobin attenuated simvastatin-induced PCSK9 overexpression in HepG2 cells. Our current findings reveal that pinostrobin is a PCSK9 inhibitor and down-regulates the PCSK9 gene expression through the up-regulation of the FoxO3a level in hepatic cells. Pinostrobin with potential PCSK9 inhibitory activity may serve as a novel agent for cholesterol regulation and lipid management.
松柏醇是一种存在于多种植物中的类黄酮植物化学物质，已被证明具有多种生物活性，如抗氧化、抗炎、抗癌和神经保护作用。本研究旨在探讨松柏醇对 PCSK9 基因表达的调控及其在肝细胞中的潜在作用机制。我们发现松柏醇（20 和 40 μM）可显著抑制 HepG2 细胞中 PCSK9 启动子活性，分别从 1.00 ± 0.16（倍）降至 0.85 ± 0.06 和 0.54 ± 0.05，同时也可显著抑制 PCSK9 mRNA 表达，分别从 1.00 ± 0.11（倍）降至 0.81 ± 0.07 和 0.58 ± 0.07。松柏醇可显著降低 PCSK9 成熟蛋白的表达水平，抑制 PCSK9 的酶活性，并增加 LDLR 蛋白水平和 LDL 摄取活性。进一步研究表明，松柏醇可显著增加核转录因子 FoxO3a 蛋白水平，增强 FoxO3a/PCSK9 启动子复合物的形成，并减弱核转录因子 HNF-1α 的启动子结合能力。用小干扰 RNA（siRNA）敲低 HepG2 细胞中的 FoxO3a 可消除松柏醇介导的 PCSK9 降低。最后，我们发现松柏醇可减弱辛伐他汀诱导的 HepG2 细胞中 PCSK9 的过度表达。本研究结果表明，松柏醇是一种 PCSK9 抑制剂，可通过上调肝细胞中 FoxO3a 水平来下调 PCSK9 基因表达。具有潜在 PCSK9 抑制活性的松柏醇可能成为一种新型的胆固醇调节和脂质管理药物。
