Investigating the process of apoptosis in HepG2 cells treated with palmitate, oleate, and palmitate/oleate combination.

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD), the most common chronic liver disease, is characterized by lipid droplet (LD) accumulation in more than 5% of hepatocytes. This study aimed to investigate apoptosis in HepG2 cells exposed to palmitate, oleate, and a combination of palmitate and oleate.

METHODS

The effective concentrations of palmitic and oleic acids were determined using the MTT assay. Subsequently, an optimal combined dose of these fatty acids was selected to induce LD formation. Intracellular LD accumulation following treatment with different concentrations of palmitate and oleate was assessed qualitatively and semi-quantitatively using Oil Red O staining and light microscopy. Expression levels of apoptosis-related genes (p53, Bax, FasL, and Bcl-2) were quantified using real-time PCR.

RESULTS

Palmitate treatment markedly reduced cell density and enhanced LD accumulation, whereas oleate exhibited milder effects. The palmitate-oleate (P&O) combination induced greater LD accumulation than oleate alone but was less cytotoxic than palmitate. At the molecular level, pro-apoptotic genes (P53, Bax, and FasL) were upregulated in all treated groups, with the highest expression in the P&O group. Conversely, the anti-apoptotic gene Bcl-2 was significantly downregulated in palmitate-treated cells.

CONCLUSION

Saturated and unsaturated fatty acids exert distinct yet interconnected effects on lipid homeostasis and hepatocyte viability. Maintaining their proper balance may be critical in preventing liver injury. Further studies are warranted to elucidate the underlying mechanisms.