Differential Modulation of WNT/β-Catenin Pathway-Associated Molecular Responses by Palmitate and Oleate in...

Palmitate (PA) and oleate (OA), the predominant saturated and monounsaturated fatty acids, respectively, may differentially influence hepatic signaling. However, their individual and combined effects on WNT/β-catenin-related responses in HepG2 cells remain incompletely characterized.

Human HepG2 cells were exposed to PA, OA, or a combined PA/OA treatment for 24 h. Cell viability was determined via MTT assay, while intracellular lipid droplet (LD) accumulation was evaluated using Oil Red O staining. Transcriptional alterations of canonical WNT/β-catenin cascade genes (WNT, CTNNB1, GSK-3β, TCF, LEF, Axin1, and Axin2) were analyzed by RT-qPCR. Protein expression levels of WNT, β-catenin, and Glypican-3 (GPC3) were evaluated to assess pathway activation.

Both fatty acids induced dose-dependent cytotoxicity and intracellular lipid accumulation, with the combined PA/OA treatment provoking the highest LD content. At the molecular level, palmitate predominantly activated the canonical cascade, significantly upregulating WNT, CTNNB1, TCF, and Axin2 mRNA, alongside elevated WNT, β-catenin, and GPC3 protein levels. Conversely, oleate selectively upregulated LEF and GSK-3β without coordinated canonical cascade activation, maintaining lower WNT and GPC3 protein expressions. Interestingly, co-treatment with PA/OA yielded intermediate molecular responses, partially attenuating palmitate-induced activation of WNT and Axin2, and facilitating a partial recovery of Axin1 expression.

PA and OA differentially modulated WNT/β-catenin pathway-associated responses in lipid-loaded HepG2 cells. PA elicited a broader response involving WNT, CTNNB1, TCF, Axin2, WNT, and β-catenin, whereas OA produced a more selective response. Their combination partially attenuated PA-associated changes, highlighting fatty acid composition as a potential determinant of cellular responses to lipotoxic stress.