3,5-Dicaffeoylquinic acid protects H9C2 cells against oxidative stress-induced apoptosis via activation of the PI3K/Akt signaling pathway

Abstract

Background: Oxidative stress-induced apoptosis plays an important role in the development of heart failure. 3,5-Dicaffeoylquinic acid (3,5-diCQA), a phenolic compound, has shown protective effects against oxidative stress in many diseases.

Objective: The objective of this study was to investigate the anti-apoptosis potential of 3,5-diCQA in cardiomyocyte cells under oxidative stress and explore its underlying mechanisms.

Design: A model of tert-butyl hydroperoxide (TBHP)-induced apoptosis in a cardiomyocyte cell line (H9C2) was established. Cell viabilities on cell lines were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) assay. The apoptosis was measured by hoechst33342 and propidium iodide (PI) fluorescent staining. PI (in red) stained the regions of cell apoptosis; Hoechet33342 (in blue) stained the nuclei. The Western blot was used to determine the expressions of related proteins such as p-PI3K: phosphorylated phosphatidylinositol- 3-kinase (p-PI3K), phosphorylated Serine and Threonine kinase AKT (p-AKT), p-PTEN, Bcl-2, Bax, and caspase-3. Afterward, a PI3K inhibitor, LY294002, was applied to confirm the influence of the PI3K/Akt pathway on TBHP-treated cells of 3,5-diCQA. Then, H9C2 cells were pre-incubated with 3,5-diCQA alone to determine if the expression of activated PI3K/Akt signaling was mediated by 3,5-diCQA in H9C2 cells.

Results: The results showed that TBHP resulted in an increase in cardiomyocyte apoptosis, whereas 3,5-diCQA treatment protected cells from TBHP-induced apoptosis in a dose-dependent manner. Moreover, 3,5-diCQA decreased expressions of Bax and caspase-3 but increased the phosphorylation levels of PI3K and Akt in TBHP-treated cells, which are the key molecules mediating cell survival, whereas phosphatase and tensin homologue deleted on chromosome 10 (PTEN) phosphorylation was unchanged. Importantly, pre-incubation with a PI3K inhibitor (LY294002) partly abolished the anti-apoptosis effects of 3,5-diCQA. Further, 3,5- diCQA enhanced the phosphorylation levels of PI3K and Akt in H9C2 cells directly, while LY294002 attenuated the effects of 3,5-diCQA on PI3K and Akt.

Conclusion: This study suggested that 3,5-diCQA rescued myocardium from apoptosis by increasing the activation of the PI3K/Akt signaling pathway.