β,β-Dimethylacrylshikonin Induces Apoptosis in Melanoma Cell Lines by NOXA Upregulation

Melanoma is the most aggressive form of skin cancer, with high metastasis rates and poor prognosis. Survival rates and possible therapies depend on the state of the tumor and its mutational profile. BRAF and NRAS are the most frequent driver mutations. Currently, there is no efficient therapy for NRAS-mutated or late-stage melanoma. In this study, the therapeutic potential of β,β-dimethylacrylshikonin (DMAS) was investigated on melanoma. The influence of DMAS was determined in five different melanoma cell lines with different mutational profiles. The effects of this compound on cell viability, apoptosis, and gene and protein expression were examined. The results obtained were validated in vivo. DMAS significantly reduced the viability of several melanoma cell lines in a concentration- and time-dependent manner. Furthermore, DMAS induced caspase-3-dependent apoptosis via NOXA upregulation, as confirmed by NOXA knockdown experiments. This is the first time that NOXA-dependent apoptosis was shown with respect to a shikonin derivative and melanoma. Additionally, tumor regression and necrosis under DMAS treatment were demonstrated in vivo. Importantly, BRAF as well as NRAS-mutated metastatic human melanoma cell lines were treated successfully in vitro and in vivo. Taken together, DMAS showed promising results and is worthy of further study.