β-Hydroxyisovalerylshikonin promotes reactive oxygen species production in HCT116 colon cancer cells, leading to caspase-mediated apoptosis

ABSTRACT Although β-hydroxyisovalerylshikonin is suggested as a potential therapeutic agent for preventing various cancers, the underlying molecular mechanisms are not completely understood. In the present study, we investigated whether β-hydroxyisovalerylshikonin enhances apoptosis by triggering reactive oxygen species production in colon cancer HCT116 cells. β-Hydroxyisovalerylshikonin significantly inhibited the viability of HCT116 cells with maximum inhibition at 4 µM. Furthermore, treatment with β-hydroxyisovalerylshikonin subsequently increased sub-G1 cells and annexin-V+ cell population. Additionally, pretreatment with the caspase-8 inhibitor, z-IETD-fmk, and the caspase-9 inhibitor, z-LETD-fmk, significantly decreased β-hydroxyisovalerylshikonin-induced apoptosis, suggesting that β-hydroxyisovalerylshikonin promotes apoptosis through both the intrinsic and the extrinsic apoptotic pathways by activating caspase-8 and caspase-9. We also found that mitochondria played an important role in β-hydroxyisovalerylshikonin-mediated apoptosis via the intrinsic pathway. Accordingly, β-hydroxyisovalerylshikonin-induced reactive oxygen species production was evident after treatment with β-hydroxyisovalerylshikonin, and pretreatment with reactive oxygen species inhibitors, N-acetyl-L-cysteine and glutathione, significantly decreased β-hydroxyisovalerylshikonin-induced reactive oxygen species production, resulting in inhibition of apoptosis, which suggests that ROS generation is required for β-hydroxyisovalerylshikonin-mediated apoptosis. Taken together, these results demonstrated that the apoptotic effect of β-hydroxyisovalerylshikonin is enhanced in colon cancer HCT116 cells via reactive oxygen species generation and triggering of the caspase pathways, indicating that β-hydroxyisovalerylshikonin has potential as a therapeutic in the treatment of colon cancers.

Inhibitory effects on the production of inflammatory mediators and reactive oxygen species by Mori folium in lipopolysaccharide-stimulated macrophages and zebrafish

ABSTRACT Mori folium, the leaf of Morus alba L. (Moraceae), has been traditionally used for various medicinal purposes from ancient times to the present. In this study, we examined the effects of water extract of Mori folium (WEMF) on the production of inflammatory mediators, such as nitric oxide (NO) and prostaglandin E2 (PGE2), and reactive oxygen species (ROS) in lipopolysaccharide (LPS)-stimulated murine RAW 264.7 macrophages. Our data indicated that WEMF significantly suppressed the secretion of NO and PGE2 in RAW 264.7 macrophages without any significant cytotoxicity. The protective effects were accompanied by a marked reduction in their regulatory gene expression at the transcription level. WEMF attenuated LPS-induced intracellular ROS production in RAW 264.7 macrophages. It inhibited the nuclear translocation of the nuclear factor-kappa B p65 subunit and the activation of mitogen-activated protein kinases in LPS-treated RAW 264.7 macrophages. Furthermore, WEMF reduced LPS-induced NO production and ROS accumulation in zebrafish. Although more efforts are needed to fully understand the critical role of WEMF in the inhibition of inflammation, the findings of the present study may provide insights into the approaches for Mori folium as a potential therapeutic agent for inflammatory and antioxidant disorders.