SIRT1 induces epithelial-mesenchymal transition by promoting autophagic degradation of E-cadherin in melanoma cells.

Melanoma is highly metastatic, and understanding of its molecular mechanism is urgently needed for the development of therapeutic targets and prognostic assessment for metastatic melanoma. SIRT1 is a nicotinamide adenine dinucleotide (NAD)-dependent protein deacetylase, belonging to the mammalian sirtuin family. It has been reported that SIRT1 is associated with metastasis in various cancers. However, the molecular mechanism of SIRT1 in melanoma metastasis remains to be clarified. Here we report that SIRT1 induces the epithelial-mesenchymal transition (EMT) by accelerating E-cadherin degradation via autophagy and facilitates melanoma metastasis. Initially, we found that SIRT1 expression was frequently elevated in metastatic melanoma compared with primary melanoma. In addition, SIRT1 induced the EMT and promoted cell migration and invasion by decreasing E-cadherin expression. Further work demonstrated that SIRT1 accelerated the autophagic degradation of E-cadherin through deacetylation of Beclin 1. In addition, inhibition of autophagy recovered E-cadherin expression and suppressed cell migration and invasion by delaying the degradation of E-cadherin in SIRT1-overexpressing cells. Overall, our findings reveal a novel molecular mechanism for SIRT1 in melanoma metastasis, indicating that SIRT1 may serve as a viable therapeutic target for metastatic melanoma.