Abstract

BACKGROUND: Excessive reactive oxygen species (ROS) stimulate mitochondrial damage that causes degenerative diseases such as cardiovascular disease (CVD). β-carotene (BC), a natural antioxidant able to counteract free radicals, acts as a cytoprotective agent. However, knowledge of the role of BC on cardiomyoblasts is limited. In this study, we explored its role on COX4, Tom20, Nfr1, Nrf2, Nf-κB, LC3, p62, caspase 3, and caspase 9 and its association with cardiomyoblast viability and survival.

MATERIAL AND METHODS: H9C2 cell lines were seeded, cultivated until 90% to 100% confluency, and treated with various doses of BC: 10 µM, 1 µM, 0.1 µM, and 0.01 µM. After 24 h, the cells were harvested, lyzed, and tested for specific related protein expressions from each dose.

RESULTS: Low-dose BC induced autophagy most effectively at 1 µM, 0.1 µM, and 0.01 µM, as indicated by a decrease of LC3II and p62 levels. We observed that Nf-kB protein levels were suppressed; Nrf2 was stimulated, but Nrf1 was not altered significantly. Further, low-dose BC might stimulate cell viability by reducing apoptotic signals of caspase 3 and 9. Notably, low-dose BC also showed potential to increase Tom20 protein levels.

CONCLUSIONS: Low-dose BC supplementation shows beneficial effects, especially at 0.01 µM, by reducing inflammation through the suppression of Nf-κB and increase of Nrf2 level. Autophagy as a cellular maintenance mechanism was also stimulated, and the amount of the mitochondria marker Tom20 increased. Taken together, results showed that specific low-dose BC is effective and might improve cell viability by stimulating autophagy, inhibiting proinflammatory factors, and suppressing apoptosis.

Keywords: Antioxidants, Mitochondria, Myocytes, Cardiac, Autophagy, biomarkers, Caspases, Cell Line, Cell Shape, Microtubule-Associated Proteins, NF-E2-Related Factor 2, NF-kappa B, Nuclear Respiratory Factor 1, Signal Transduction, beta Carotene