Inhibiting MT2-TFE3-dependent autophagy enhances melatonin-induced apoptosis in tongue squamous cell carcinoma
Inhibiting MT2-TFE3-dependent autophagy enhances melatonin-induced apoptosis in tongue squamous cell carcinoma
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DOI：
10.1111/jpi.12457
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发表时间：
2018-03-01
影响因子：
10.3
通讯作者：
Zhou, Zhou
中科院分区：
文献类型：
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作者：
Fan, Tengfei;Pi, Huifeng;Zhou, Zhou
自噬调节是舌鳞状细胞癌(TSCC)的潜在治疗策略。褪黑素具有显著的抗癌活性。然而，褪黑素是否诱导自噬及其在舌鳞癌细胞死亡中的作用尚不清楚。在此，我们发现褪黑素诱导了舌鳞癌细胞系Cal27的显著凋亡。除了诱导细胞凋亡外，我们还证明了褪黑素诱导了Cal27细胞的自噬通量，这体现在GFP-LC3斑点的形成，以及LC3-II的上调和SQSTM1/p62的下调。此外，自噬的药物或基因阻断增强了褪黑素诱导的细胞凋亡，表明自噬在褪黑素处理的Cal27细胞中具有细胞保护作用。机制上，褪黑素诱导TFE3(Ser321)去磷酸化，随后激活TFE3核转位，增加TFE3报告活性，从而促进自噬相关基因的表达和溶酶体的生物发生。褪黑素膜受体阻滞剂Luzindole或MT2-siRNA部分阻断了褪黑素促进mTORC1/TFE3信号转导的能力。此外，我们在异种移植小鼠模型中验证了褪黑素与羟氯喹或TFE3-siRNA通过抑制自噬而发挥协同抗肿瘤作用。重要的是，TFE3的表达与TSCC的发展和预后不良呈正相关。总之，我们证明了褪黑素诱导的依赖TFE3的自噬增加是通过TSCC中的褪黑素膜受体介导的。这些数据还表明，阻断褪黑素膜受体-TFE3依赖的自噬以增强褪黑素的活性值得进一步关注，作为TSCC的一种治疗策略。
Autophagy modulation is a potential therapeutic strategy for tongue squamous cell carcinoma (TSCC). Melatonin possesses significant anticarcinogenic activity. However, whether melatonin induces autophagy and its roles in cell death in TSCC are unclear. Herein, we show that melatonin induced significant apoptosis in the TSCC cell line Cal27. Apart from the induction of apoptosis, we demonstrated that melatonin-induced autophagic flux in Cal27 cells as evidenced by the formation of GFP-LC3 puncta, and the upregulation of LC3-II and downregulation of SQSTM1/P62. Moreover, pharmacological or genetic blockage of autophagy enhanced melatonin-induced apoptosis, indicating a cytoprotective role of autophagy in melatonin-treated Cal27 cells. Mechanistically, melatonin induced TFE3((Ser321)) dephosphorylation, subsequently activated TFE3 nuclear translocation, and increased TFE3 reporter activity, which contributed to the expression of autophagy-related genes and lysosomal biogenesis. Luzindole, a melatonin membrane receptor blocker, or MT2-siRNA partially blocked the ability of melatonin to promote mTORC1/TFE3 signaling. Furthermore, we verified in a xenograft mouse model that melatonin with hydroxychloroquine or TFE3-siRNA exerted a synergistic antitumor effect by inhibiting autophagy. Importantly, TFE3 expression positively correlated with TSCC development and poor prognosis in patients. Collectively, we demonstrated that the melatonin-induced increase in TFE3-dependent autophagy is mediated through the melatonin membrane receptor in TSCC. These data also suggest that blocking melatonin membrane receptor-TFE3-dependent autophagy to enhance the activity of melatonin warrants further attention as a treatment strategy for TSCC.