Co-Delivery of Hispolon and Doxorubicin Liposomes Improves Efficacy Against Melanoma Cells

Hispolon is a small molecular weight polyphenol that has antioxidant, anti-inflammatory, and anti-proliferative activities. Our recent study has demonstrated hispolon as a potent apoptosis inducer in melanoma cell lines. Doxorubicin is a broad spectrum first-line treatment for various kinds of cancers. In this study, co-delivery of doxorubicin and hispolon using a liposomal system in B16BL6 melanoma cell lines for synergistic cytotoxic effects was investigated. Liposomes were prepared using a lipid film hydration method and loaded with doxorubicin or hispolon. The formulations were characterized for particle size distribution, release profile, and encapsulation efficiency (EE). In addition, in vitro cytotoxicity, in vitro cell apoptosis, and cellular uptake were evaluated. Liposomes exhibited small particle size (mean diameter ~ 100 nm) and narrow size distribution (polydispersity index (< 0.2) and high drug EE% (> 90%). The release from liposomes showed slower release compared to free drug solution as an additional time required for the release of drug from the liposome lipid bilayer. Liposome loaded with doxorubicin or hispolon exhibited significantly higher cytotoxicity against B16BL6 melanoma cells as compared to doxorubicin solution or hispolon solution. Likewise, co-delivery of hispolon and doxorubicin liposomes showed two-fold and three-fold higher cytotoxicity, as compared to hispolon liposomes or doxorubicin liposomes, respectively. In addition, co-delivery of doxorubicin and hispolon in liposomes enhanced apoptosis more than the individual drugs in the liposome formulation. In conclusion, the co-delivery of hispolon and doxorubicin could be a promising therapeutic approach to improve clinical outcomes against melanoma.

Elucidating the anti-melanoma effect and mechanisms of Hispolon

There is a rapid increase in the incidence of melanoma which has led to a global crisis. Thus, there is a great need for developing novel, safe and effective drugs for the treatment of melanoma. Hispolon is a small molecular weight polyphenol derived from Phellinus linteus, which has antioxidant, anti-inflammatory and anti-proliferative activities. Hispolon has been reported to induce apoptosis in gastric cancer, hepatocellular carcinoma, and myeloid leukemia. However, the anticancer effect in melanoma is not well elucidated. Thus, our present study was to investigate the anti-cancer effect of hispolon on melanoma cancer cells. B16BL6 cells were treated with different concentrations of hispolon for 24 h and the effect on oxidative stress, mitochondrial functions, apoptosis and cell proliferation were studied. Hispolon is a potent generator of reactive oxygen species, nitrite and lipid peroxide levels. Furthermore, it significantly inhibits the expression of Bcl-2 and promotes the expression of Bax, increases the activity of caspase 1 and 3, inhibits mitochondrial Complex I and IV activities. By the above mechanisms, hispolon dose-dependently exhibited the antimelanoma effect similar to the well established pharmacological agent, curcumin. Thus, hispolon can be a potent anti-melanoma drug in the future if the pharmacodynamic effects and the toxicological studies are appropriately carried out.