HOXB9 a miR-122–5p regulated gene, suppressed the anticancer effects of brusatol by upregulating SCD1 expression in melanoma

Brusatol (Bru), a Chinese medicine Brucea javanica extract, has a variety of antitumour effects. However, its role and underlying mechanism in melanoma have not been fully elucidated. In this study, we found that brusatol inhibited melanoma cell proliferation and migration and promoted cell apoptosis in vitro, in addition to suppressing melanoma cell tumorigenesis in vivo. Further studies on the mechanism revealed that brusatol significantly downregulated the expression of stearoyl-CoA desaturase 1 (SCD1). Increased SCD1 expression could impair the antitumour effects of brusatol on melanoma cells. Subsequently, we found that HOXB9, an important transcription factor, was directly bound to the promoter of SCD1, facilitating its transcription. Overexpression of HOXB9 inhibited brusatol-induced SCD1 reduction and promoted cell survival. Furthermore, our results revealed that miR-122–5p was significantly increased in response to brusatol treatment and led to a decrease in HOXB9 in melanoma. Collectively, our data suggested that the miR-122–5p/HOXB9/SCD1 axis might play an important role in the antitumour effects of brusatol and that brusatol might have potential clinical implications in melanoma therapy.