Black Raspberry Extract Enhances LDL Uptake in HepG2 Cells by Suppressing PCSK9 Expression to Upregulate LDLR...

Area of Science:

• Phytochemistry
• Molecular Biology
• Pharmacology

Background:

• Black raspberry extract (BRE) is traditionally used in Asia for prostate, urinary, and hyperlipidemia conditions.
• BRE exhibits significant lipid-lowering effects, particularly relevant for managing high cholesterol.

Purpose of the Study:

• To evaluate the antihypercholesterolemia activity of BRE.
• To investigate the molecular mechanisms of BRE's action, focusing on PCSK9 (proprotein convertase subtilisin/kexin type 9) regulation in liver cells.

Main Methods:

• Utilized a reporter-based functional assay in HepG2 cells to screen for extracts suppressing PCSK9.
• Employed quantitative real-time PCR, Western blot, and immunofluorescence to assess BRE's impact on PCSK9 and LDLR (low-density lipoprotein receptor) expression.
• Measured HepG2 cell LDLR activity via an LDL uptake assay.

Main Results:

• BRE was found to modulate LDLR expression by suppressing hepatic PCSK9 expression.
• Simvastatin alone increased PCSK9 expression in HepG2 cells.
• The combination of simvastatin and BRE showed synergistic induction of LDLR expression and LDL-C uptake, with BRE counteracting simvastatin-induced PCSK9 elevation.

Conclusions:

• BRE suppresses hepatic PCSK9 expression, leading to increased LDLR expression and enhanced LDL-C uptake by hepatocytes.
• BRE's ability to suppress PCSK9 may enhance the hypolipidemic effects of statins, suggesting a potential synergistic therapeutic approach.