Dihydromyricetin induced lncRNA MALAT1 - TFEB-dependent autophagic cell death in cutaneous squamous cell carcinoma.

Cutaneous squamous cell carcinoma (CSCC) is the second most common skin cancer. Dihydromyricetin (DHM), a Rattan tea extract, has been shown to have antitumor activity with no obvious toxicity to normal cells in vitro and in vivo. However, its efficacy in the treatment of CSCC and the underlying antitumor mechanism has not been fully elucidated yet. In our study, DHM increased autophagic flux in the A431 cells, as evidenced by the upregulation of LC3-II and downregulation of P62/SQSTM1. Moreover, the pharmacological or genetic blocking autophagy decreased DHM-induced cell death, indicating DHM triggered autophagic cell death in A431 cells. Specifically, DHM induced TFEB(Ser142) de-phosphorylation, activated TFEB nuclear translocation and increased of TFEB reporter activity, which contributed to the expression of autophagy-related genes and subsequent initiated autophagic cell death in A431 cells. Importantly, DHM decreased IncRNA MALAT1 expression and MALAT1 overexpression abrogated the effects of DHM on TFEB-dependent autophagy both in vitro and in vivo. Taken together, DHM induces CSCC cell death via inducing excessive autophagy, which is mediated through the MALAT1-TFEB pathway. Therefore, DHM may be beneficial for the development of chemotherapy for CSCC.