Department of Oncology, Renji Hospital, School of Medicine, Shanghai Jiaotong University, 160 Pujian Road, Shanghai, 200127, China.
Department of Pathology, Eye Ear Nose and Throat Hospital, Fudan University, 83 Fenyang Road, Shanghai, 200031, China.
BMC Cancer. 2018 Oct 23;18(1):1032. doi: 10.1186/s12885-018-4954-9.
It was demonstrated that long non-coding RNAs occupied an important position in tumor pathogenesis and progression. We have previously found that the metastasis-associated lung adenocarcinoma transcript 1 (MALAT-1) promotes cell proliferation and metastases in pancreatic ductal adenocarcinoma (PDAC). The present study was aimed to discuss the underlying mechanisms.
Bioinformatics method was used to identify the miRNA target of MALAT-1. Expressions of relative genes were assessed by quantitative real-time PCR and western blotting, respectively. Sulforhodamine B assay and Transwell assay were employed to detect cell proliferation, migration and invasion, respectively. Moreover, RNA immunoprecipitation was performed to determine whether RNA-induced silencing complex contained MALAT-1 and its potential binding miRNA. Luciferase assays was used to confirm potential binding site.
Bioinformatics search predicted that miR-200c-3p was a direct target of MALAT-1. Further, we found a reciprocal suppression between MALAT-1 and miR-200c-3p expression. In terms of mechanisms, high MALAT-1 and low miR-200c-3p may form a novel feedback loop. On the one hand, MALAT-1 functioned as a competing endogenous RNA to suppress miR-200c-3p expression, leading to upregulation of ZEB1 expression. On the other hand, miR-200c-3p inhibited the level of MALAT-1 expression was in a way similar to miRNA-mediated downregulation of target genes. Clinical data further indicated that MALAT-1 and ZEB1 expression was negatively correlated with miR-200c-3p transcript level of PDAC tissues. There was a positive correlation between MALAT-1 and ZEB1 level. MALAT-1 (high)/miR-200c-3p (low) correlated with shorter overall survival of PDAC patients. Multivariate analysis revealed that both MALAT-1 and miR-200c-3p levels were independent prognostic factors.
Our findings firstly revealed a novel feedback loop between high MALAT-1 and low miR-200c-3p. Targeting the feedback loop between high MALAT-1 and low miR-200c-3p will be a therapeutic strategy for PDAC.
长链非编码 RNA 在肿瘤的发病机制和进展中占有重要地位。我们之前发现，转移相关肺腺癌转录物 1（MALAT-1）促进胰腺导管腺癌（PDAC）中的细胞增殖和转移。本研究旨在探讨其潜在的机制。
使用生物信息学方法鉴定 MALAT-1 的 miRNA 靶标。通过定量实时 PCR 和 Western blot 分别评估相对基因的表达。使用磺酰罗丹明 B 测定法和 Transwell 测定法分别检测细胞增殖、迁移和侵袭。此外，进行 RNA 免疫沉淀以确定 RNA 诱导的沉默复合物是否包含 MALAT-1 及其潜在的结合 miRNA。使用荧光素酶测定法证实潜在的结合位点。
生物信息学搜索预测 miR-200c-3p 是 MALAT-1 的直接靶标。此外，我们发现 MALAT-1 和 miR-200c-3p 的表达呈相互抑制关系。就机制而言，高 MALAT-1 和低 miR-200c-3p 可能形成新的反馈回路。一方面，MALAT-1 作为竞争性内源性 RNA 发挥作用，抑制 miR-200c-3p 的表达，导致 ZEB1 表达上调。另一方面，miR-200c-3p 以类似于 miRNA 介导的靶基因下调的方式抑制 MALAT-1 表达水平。临床数据进一步表明，PDAC 组织中 MALAT-1 和 ZEB1 表达与 miR-200c-3p 转录水平呈负相关。MALAT-1 和 ZEB1 水平呈正相关。MALAT-1（高）/miR-200c-3p（低）与 PDAC 患者的总生存期较短相关。多变量分析显示，MALAT-1 和 miR-200c-3p 水平均为独立的预后因素。
我们的研究结果首次揭示了 MALAT-1 高表达和 miR-200c-3p 低表达之间的新的反馈环。靶向 MALAT-1 高表达和 miR-200c-3p 低表达之间的反馈环将成为 PDAC 的治疗策略。
