Department of General Surgery, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, China.
Department of Ophthalmology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200080, China.
J Exp Clin Cancer Res. 2021 Jan 14;40(1):31. doi: 10.1186/s13046-020-01813-6.
MicroRNAs (miRNAs) are abundant in tumor-derived extracellular vesicles (EVs) and the functions of extracellular miRNA to recipient cells have been extensively studied with tumorigenesis. However, the role of miRNA in EV secretion from cancer cells remains unknown.
qPCR and bioinformatics analysis were applied for determining extracellular let-7a expression from CRC patient serum and cells. Nanosight particle tracking analysis was performed for investigating the effect of let-7a on EV secretion. Luciferase reporter assays was used for identifying targeted genes synaptosome-associated protein 23 (SNAP23). In vitro and in vivo assays were used for exploring the function of let-7a/SNAP23 axis in CRC progression. Bioenergetic assays were performed for investigating the role of let-7a/SNAP23 in cellular metabolic reprogramming.
let-7a miRNA was elevated in serum EVs from CRC patients and was enriched in CRC cell-derived EVs. We determined that let-7a could suppress EV secretion directly targeting SNAP23. In turn, SNAP23 promotes EV secretion of let-7a to downregulate the intracellular let-7a expression. In addition, we found a novel mechanism of let-7a/SNAP23 axis by regulating mitochondrial oxidative phosphorylation (OXPHOS) through Lin28a/SDHA signaling pathway.
Let-7a plays an essential role in not only inhibiting EV secretion, but also suppressing OXPHOS through SNAP23, resulting in the suppression of CRC progression, suggesting that let-7a/SNAP23 axis could provide not only effective tumor biomarkers but also novel targets for tumor therapeutic strategies.
微小 RNA（miRNAs）在肿瘤来源的细胞外囊泡（EVs）中含量丰富，其对受体细胞的功能已在肿瘤发生中得到广泛研究。然而，miRNA 在癌细胞 EV 分泌中的作用仍不清楚。
qPCR 和生物信息学分析用于确定 CRC 患者血清和细胞中外泌体 let-7a 的表达。纳米粒子跟踪分析用于研究 let-7a 对 EV 分泌的影响。荧光素酶报告基因测定用于鉴定靶基因突触相关蛋白 23（SNAP23）。体外和体内实验用于研究 let-7a/SNAP23 轴在 CRC 进展中的作用。生物能量学测定用于研究 let-7a/SNAP23 在细胞代谢重编程中的作用。
CRC 患者血清 EV 中的 let-7a miRNA 升高，并且在 CRC 细胞来源的 EV 中富集。我们确定 let-7a 可以通过直接靶向 SNAP23 抑制 EV 分泌。反过来，SNAP23 促进 let-7a 的 EV 分泌，从而下调细胞内 let-7a 的表达。此外，我们通过 Lin28a/SDHA 信号通路发现了 let-7a/SNAP23 轴的新机制，通过调节线粒体氧化磷酸化（OXPHOS）。
Let-7a 通过 SNAP23 不仅在抑制 EV 分泌中起重要作用，而且在抑制 OXPHOS 中起重要作用，从而抑制 CRC 的进展，表明 let-7a/SNAP23 轴不仅可以提供有效的肿瘤生物标志物，而且可以为肿瘤治疗策略提供新的靶点。
