High glucose concentrations induce PCSK9, RAGE expression and early lipid accumulation in HepG2 cells

Abstract

Introduction: Metabolic dysfunction-associated steatotic liver disease is characterized by hepatic fat accumulation greater than 5% and may be both a consequence and a driver of hyperglycemia. This condition represents a growing global health burden and has a high estimated prevalence in Mexico. Because liver biopsy remains the reference method for diagnosis, the identification of non-invasive molecules associated with early hepatic lipid accumulation is clinically relevant. In this context, hyperglycemia and advanced glycation end products may contribute to metabolic and inflammatory alterations involved in early disease progression.

Objective: To identify molecules associated with early hepatic lipid accumulation under high glucose conditions and exposure to advanced glycation end products.

Methodology: Differential protein expression was analyzed in liver tissue from healthy individuals and individuals with hepatic steatosis using public microarray datasets GSE63067 and GSE49541 from the Gene Expression Omnibus database. Molecules identified through the in silico analysis were experimentally evaluated in HepG2 cells exposed to high glucose concentrations, Nε-carboxymethyl-lysine, and oleic acid. Intracellular lipid accumulation in HepG2 cells was evaluated using Oil Red O staining. Total proteins were obtained using RIPA buffer, and protein abundance was assessed by Western blot.

Results: The in silico analysis identified 12 molecules associated with glucose metabolism, lipid metabolism, including PCSK9, and inflammatory pathways, including interleukins. Experimental assays showed increased abundance of PCSK9, RAGE and IL-6, together with greater intracellular lipid accumulation, particularly after exposure to high glucose plus Nε-carboxymethyl-lysine. These findings suggest that the molecules identified in silico may be associated with early metabolic changes related to hepatic steatosis under hyperglycemic conditions.

Conclusions: Treatment of HepG2 cells with high concentrations of glucose and plus Nε-carboxymethyl-lysine could induce an inflammatory and metabolic response resembling early lipid accumulation observed in metabolic dysfunction-associated steatotic liver disease, surpassing the effects elicited by oleic acid exposure. This response may be mediated by increased lipogenesis and advanced glycation end product formation, which activate inflammatory processes and may significantly induce PCSK9 expression, contributing to disease progression. These results support PCSK9 and related inflammatory-metabolic molecules as potential candidates for future studies on early, non-invasive detection of metabolic liver dysfunction.