N(6)-methyladenosine-mediated miR-380-3p maturation and upregulation promotes cancer aggressiveness in pancreatic cancer

N(6)-methyladenosine (m6A)-modified microRNAs (miRNAs) are relevant to cancer progression. Also, although the involvement of miR-380-3p in regulating cancer progression in bladder cancer and neuroblastoma has been preliminarily explored, its role in other types of cancer, such as pancreatic cancer (PC), has not been studied. Thus, this study aimed to investigate the role of miR-380-3p in regulating PC progression. Here, through performing Real-Time qPCR, we evidenced that miR-380-3p was significantly upregulated in the clinical pancreatic cancer tissues and cells compared to their normal counterparts. Interestingly, miR-380-3p was enriched with m6A modifications, and elimination of m6A modifications by deleting METTL3 and METTL14 synergistically suppressed miR-380-3p expressions in PC cells. Next, the gain and loss-of-function experiments verified that knockdown of miR-380-3p suppressed cell proliferation, epithelial–mesenchymal transition (EMT), and tumorigenesis in PC cells in vitro and in vivo, whereas miR-380-3p overexpression had opposite effects. Furthermore, the underlying mechanisms were uncovered, and our data suggested that miR-380-3p targeted the 3’ untranslated regions (3ʹUTRs) of PTEN for its inhibition and degradation, resulting in the activation of the downstream Akt signal pathway. Moreover, the rescuing experiments validated that both PTEN overexpression and Akt pathway inhibitor LY294002 abrogated the promoting effects of miR-380-3p overexpression on cancer aggressiveness in PC cells. Collectively, this study firstly investigated the role of the m6A-associated miR-380-3p/PTEN/Akt pathway in regulating PC progression, which provided novel therapeutic and diagnostic biomarkers for this cancer.N6-甲基腺嘌呤(N(6)-methyladenosine，m6A)修饰的微小RNA(microRNAs，miRNAs)与癌症进展密切相关。尽管已有研究初步探索了miR-380-3p在膀胱癌及神经母细胞瘤中调控癌症进展的作用，但该分子在胰腺癌(pancreatic cancer，PC)等其他癌种中的功能尚未被阐明。因此，本研究旨在探讨miR-380-3p对胰腺癌进展的调控作用。本研究通过实时定量聚合酶链反应(Real-Time qPCR)证实，相较于正常对照样本，miR-380-3p在临床胰腺癌组织及胰腺癌细胞中显著上调。有趣的是，miR-380-3p存在丰富的m6A修饰；通过敲除METTL3与METTL14消除m6A修饰，可协同抑制胰腺癌细胞中miR-380-3p的表达。后续的功能获得与功能缺失实验验证显示，敲低miR-380-3p可在体外及体内抑制胰腺癌细胞的增殖、上皮间质转化(epithelial–mesenchymal transition，EMT)及肿瘤发生，而过表达miR-380-3p则会产生相反的效应。本研究进一步揭示了其潜在分子机制：数据表明，miR-380-3p可靶向结合张力蛋白同源缺失的第10号染色体(PTEN)的3'非翻译区(3ʹUTRs)，进而抑制并降解PTEN，最终激活下游Akt信号通路。挽救实验证实，过表达PTEN或使用Akt通路抑制剂LY294002，均可抵消miR-380-3p过表达对胰腺癌细胞侵袭性的促进作用。综上，本研究首次阐明了m6A相关的miR-380-3p/PTEN/Akt通路在胰腺癌进展中的调控作用，为该癌种提供了全新的治疗与诊断生物标志物。