KRAS突变调控miR-139-5p介导结直肠癌恶性生物学行为的功能与机制研究

Over 30% of patients with colorectal cancer (CRC) harbor KRAS mutation, which indicates the poor prognosis in patients with CRC. microRNAs (miRNAs) play essential roles in gene expression regulation during carcinogenesis; however, miRNAs dysregulation in KRAS-mutant colorectal cancer has not been fully explored. We previously found that miR-139-5p was down-regulated in KRAS mutant CRC cell lines and tissues compared with their wild-type KRAS counterparts and overexpression of miR-139-5p in KRAS mutant CRC cells inhibited the proliferation, migration, and invasion of CRC cells. All above results indicated that that miR-139-5p plays an important role in KRAS mutation CRC. In this study, we aim to demonstrate the function of miR-139-5p in KRAS mutant CRC through in vitro and in vivo functional studies. In addition, we will utilize high-throughput methods including cDNA microarray and iTRAQ analysis to reveal the target molecules of miR-139-5p and the related signaling pathways. Mechanically, we investigate the role and mechanism of KRAS in regulation of miR-139-5p expression at both transcriptional and post-transcriptional levels. Finally, we will explore the therapeutic potential and application values of miR-139-5p administration in CRC PDX and organoid models, which may provide a potential therapeutic strategy for colon cancers exhibiting aberrant KRAS pathway activation.

超过30%的结直肠癌患者存在KRAS突变，是预后不良的重要因素。miRNA在肿瘤发生发展中发挥重要作用，但受KRAS突变调控的miRNA及调控机制罕有报道。我们前期发现miR-139-5p在KRAS突变结直肠癌细胞系及临床标本中表达降低，过表达miR-139-5p抑制KRAS突变癌细胞的增殖和侵袭能力，提示KRAS突变调控miR-139-5p表达，在结直肠癌恶性生物学行为中发挥重要作用。本研究拟通过体内外功能实验，阐明miR-139-5p在KRAS突变结直肠癌中发挥的作用；联合应用基因芯片和蛋白质组iTRAQ，阐明miR-139-5p调控的关键靶分子和信号网络；探索KRAS突变致miR-139-5p表达下调的转录机制及表观遗传学机制；在结直肠癌PDX小鼠模型及organoid模型中进一步验证，探索miRNA治疗可行性。本研究将深入对KRAS突变结直肠癌的认识，为其治疗提供新靶点新策略。

超过30%的结直肠癌患者存在KRAS突变,是预后不良的重要因素。miRNA在肿瘤发生发展中发挥了重要作用,但受KRAS突变调控的miRNA及调控机制罕有报道。我们前期发现miR-139-5p在KRAS突变结直肠癌细胞系及临床标本中表达降低,过表达miR-139-5p抑制KRAS突变癌细胞的增殖和侵袭能力,提示KRAS突变调控miR-139-5p表达,在结直肠癌恶性生物学行为中发挥重要作用。获资助后，我们的研究发现：1. 与野生型对应物相比，KRAS突变的CRC细胞和组织中的miR-139-5p显著下调。低miR-139-5p表达与CRC患者的侵袭性表型和不良预后相关。2. miR-139-5p过表达在体外抑制 CRC细胞增殖、迁移和侵袭，使肿瘤对化疗敏感，并在体内抑制肿瘤的生长和转移。3.转录组分析确定了Ras通路（JUN 和 FOS）和Wnt通路（CTNNB1和DVL1）和上皮间质转化(EMT)过程 (ZEB1)中的多个分子作为 miR-139-5p的直接靶标，负相关关系在CRC临床组织中得到证实。4. KRAS突变细胞中异常激活的Wnt信号被证明通过TCF4转录抑制miR-139-5p表达，形成miR-139-5p/Wnt信号双负反馈回路。由此，我们将miR-139-5p鉴定为KRAS突变反应性的miRNA，并证实其参与CRC进展。KRAS突变破坏了miR-139-5p/Wnt信号交互负反馈机制，这可能导致miR-139-5p下调，导致癌信号通路和EMT通路激活。以上结果揭示了KRAS驱动恶性转化的转录调控模式，并发现miR-139-5p作为CRC中Ras和Wnt信号通路互作的新型调节分子，主要研究结果以通讯作者发表在Theranostics 2020。本研究深入对KRAS突变结直肠癌的认识,为其治疗提供新靶点新策略。共10篇SCI论文和5篇中文核心期刊论文受该基金资助，并均已标注。培养博士研究生2名，硕士研究生5名。

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