Pinostrobin Inhibits Proprotein Convertase Subtilisin/Kexin-type 9 (PCSK9) Gene Expression through the Modulation of FoxO3a Protein in HepG2 Cells

Abstract

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.

EGFR/FOXO3A/LXR-α Axis Promotes Prostate Cancer Proliferation and Metastasis and Dual-Targeting LXR-α/EGFR Shows Synthetic Lethality

“…Our conclusion is supported by the following lines of evidence: (1) Among 59 tumor TMA samples, the high EGFR staining group is largely associated with the low staining group of LXR-α, and vice versa; (2) Among prostate cell lines tested, there is a general tendency of inversed protein levels between EGFR and FOXO3A. FOXO3A could induce cholesterol regulation and lipid management (52), and be regulated by EGFR (44)(45)(46); (3) EGFR inhibitor Afatinib inhibited p-AKT and increased FOXO3A and LXR-α, as did AKT inhibitor LY294002; (4) The levels of endogenously expressed LXR-α were increased upon FOXO3A transfection, while they were reduced by FOXO3A knockdown; and (5) Overexpression of FOXO3A elevated the level of LXR-α mRNA, and vice versa.…”

Beneficial impact of epigallocatechingallate on LDL-C through PCSK9/LDLR pathway by blocking HNF1α and activating FoxO3a

“…Among these FoxO proteins, FoxO3a is a predominant player in the regulation of cholesterol homeostasis in hepatic cells. It has been reported that the loss of FoxO3a leads to increased lipid synthesis in the liver [25,50]. In hepatic FoxO3-deficient mice, both the hepatic and plasma cholesterol levels were increased.…”

“…Tai et al [37] reported that curcumin reduced PCSK9 via down regulating HNF1α. FoxO TFs have been reported to play an important role in several essential cellular functions including cell proliferation, apoptosis, lipid metabolism and liver function [25,48,49]. Among these FoxO proteins, FoxO3a is a predominant player in the regulation of cholesterol homeostasis in hepatic cells.…”

“…HNF1α Stealth siRNA duplexes (Life technologies, Carlsbad, CA, USA) targeting sequences: 5′-UCG AUA CCA CUG GCC UCA ATT-3′ and 5′-UUG AGG CCA GUG GUA UCG ATT-3′. FoxO3a Stealth siRNA duplexes (Life technologies, Carlsbad, CA, USA) targeting sequences: 5′-AAC CCU CCA AUG UGU UUC AAC TT-3′ and 5′-GUU GAA ACA CAU UGG AGG GUU TT-3′ [25]. The stealth RNAi negative control Duplex (Life technologies, Carlsbad, CA, USA) were used as a control.…”

Naturally Occurring PCSK9 Inhibitors

“…Schltr., Zingiberaceae], was studied with respect of its potential influence on PCSK9. The treatment of HepG2 with 20 and 40 µM of pinostrobin led to a dose-dependent reduction of mRNA and protein expression of PCSK9, and a reduction of its catalytic activity, resulting in increased LDLR expression and LDL uptake by the cells [113]. Stereospecific differences in the pharmacokinetic profile of pinostrobin have been observed in rats after iv and oral administrations (Figure 1 and Table 1) [114].…”