4-Hydroxynonenal-induced apoptosis in rat hepatic stellate cells: Mechanistic approach

Background and Aim: Although lipid peroxidation products act as apoptotic signals for several cell types, including hepatic stellate cells, the underlying mechanisms are not well understood. In this study we determined if: (i) 4-hydroxy-2,3-nonenal (HNE) induces apoptosis in two rat stellate cell lines, HSC-T6 and CFSC-2G; and (ii) if apoptosis is regulated at the transcriptional and/or translational level. Methods: HSC-T6 and CFSC-2G cells were treated with HNE and total RNA and protein extracted. mRNA and protein expression levels of pro- and antiapoptotic factors were determined. The effects of HNE on activation, morphology and cell death by apoptosis were also studied. Results: HNE caused dose-dependent apoptosis in both HSC-T6 and CFSC-2G cell lines. Apoptosis in HSC-T6 cells was associated with increased mRNA expression of the pro-apoptotic adaptors/regulators FasR, FasL, Bax, and caspases-2 and -3. In contrast, CFSC-2G cells showed no changes in FasR, Bax and caspase-3 mRNA levels. Caspase-3 activity was elevated in T6 but not in 2G cells. Changes in protein expression generally paralleled the mRNA findings. Conclusions: HNE-induced apoptosis of both CFSC-2G and HSC-T6 rat hepatic stellate cells is associated with changes in mRNA and protein expression of several apoptotic adaptors/regulators. The underlying mechanism for HNE-induced apoptosis may involve both transcriptional and translational regulatory steps.