Sanggenol L promotes apoptotic cell death in melanoma skin cancer cells through activation of caspase cascades and apoptosis-inducing factor

Sanggenol L is one component of root bark of Morus alba. The molecular and cellular mechanisms of sanggenol L effects on melanoma cells are not well known. Recently, melanoma is the most common skin cancer with a high mortality rate not only in United States, but also in East Asia. Therefore, safe and effective treatments for melanoma treatment are required. In this study, we investigated whether or not sanggenol L possesses anticancer activity in human and mouse melanoma skin cancer cells. Sanggenol L treatment exerted significant cell growth inhibitory effects and inhibited colony formation capacity against B16, SK-MEL-2, and SK-MEL-28 melanoma skin cancer cells, whereas HaCaT human epithelial keratinocyte cells was unaffected by sanggenol L treatment. Sanggenol L treatment resulted in apoptotic cell death in melanoma skin cancer cells, which was characterized by accumulation of apoptotic cells, nuclear condensation, and apoptotic bodies. We also showed that sanggenol L treatment induced caspase-dependent apoptosis (up-regulation of Box and cleaved-PARP or down-regulation of Bid, Bcl-2, procaspse-3, -8, and -9), induction of caspase-independent apoptosis (up-regulation of AIF and Endo G on cytosol) in melanoma skin cancer cells. These results suggest that sanggenol L induces caspase-dependent and -independent apoptosis in melanoma skin cancer cells.