Mir-139调控IGF1R通路导致肿瘤细胞干细胞化在结肠癌耐药性中的作用

Colorectal cancer (CRC) is the high incidence of malignant tumors, and its incidence has been an upward trend. Chemotherapy is the mainstream method of treatment against it. However, cancerous cells frequently develop multidrug resistance (MDR)to chemotherapy agents.In our study, we described the down-regulation and function of miR-139 in colorectal cancer (CRC) metastasis.Decreased miR-139 in CRC tissue was associated with disease progression and metastasis. Based on these data, we screened two strains of colon cancer stem cell.expression surface markers CD44 / CD133 as cancer stem cell model. Two strains of double positive cells were displayed on multyidrug resistance. MiR-139 downregulated in colorectal cancer cells was demonstrated to play a role in the development of MDR in colon cancer stem cells.We will further investigate the mechanism of miR-139 modulating MDR of colon cancer stem cell by targeting IGF-1R,and observe the sensitivities of tumor stem cell exposed to anti-cancer medicine after miR-139 over expression in tumor stem cells and normal cancer stem cells.when transplant in the nude mice. We focus on the miRNA mediated cancer stem cell regulation mechanism. In order to find novel cancer therapy.

结肠癌是人类高发恶性肿瘤，其发病率一直呈上升趋势。目前化学疗法对于结肠癌效果不佳的主要原因是结肠癌细胞的多药耐药性，是肿瘤治疗最大障碍之一。我们之前报道了microRNA-139（miR-139）这一重要的抑癌基因，其表达量在结肠癌病例组织及细胞株中随肿瘤恶性程度增加而下降。本项目在前期工作的基础上，筛选出了两株肿瘤干细胞表面标志物CD44/CD133双阳性的结肠癌细胞株作为肿瘤干细胞模型，两株双阳性细胞均表现出对多种抗癌药的耐药性。本项目研究结肠癌细胞中异常表达的miR-139参与诱导结肠癌干细胞多药耐药；明确miR-139通过IGF-1R通路在肿瘤干细胞中所起的调控作用的机制；同时观察miR-139过表达的肿瘤干细胞和正常肿瘤干细胞在裸鼠体内成瘤后对临床抗癌药物的敏感性的变化。该研究从miRNA角度解释结肠癌肿瘤干细胞形成的机制，以期为治疗结肠癌多药耐药寻找新靶点提供理

结肠癌是人类高发恶性肿瘤，其发病率一直呈上升趋势。目前化学疗法对于结肠癌效果不佳的主要原因是结肠癌细胞的多药耐药性，是肿瘤治疗最大障碍之一。miRNAs可以促进或抑制肿瘤复发和多药耐药。我们前期的研究发现在结肠癌患者病例样本中miR-139-5p的表达显著下调，然而miR-139-5p调控结肠癌多药耐药的机制尚不明确。研究中，我们建立了结肠癌多药耐药细胞模型HCT116/LOHP和HCT8/VCR耐药株，并发现其高表达肿瘤干细胞相关标志物CD44和CD133。且相比亲本株，耐药株中miR-139-5p的表达显著下调。肿瘤干细胞被推测是产生多药耐药的重要因素之一，因此我们以CD133和CD44表面标志物流式分选出CD133+/CD44+HCT116和CD133+/CD44+HCT8细胞作为肿瘤干细胞，用于后续实验。在双阳性细胞中瞬转miR-139-5p可以逆转结肠癌干细胞的多药耐药性。其次，为了进一步探究miR-139-5p调控结肠癌干细胞多药耐药的机制，我们通过miRanda，PicTar，TargetScan，搜索和分析了与miR-139-5p3’UTR区域保守结合的靶基因，其中就包括维持干细胞功能的蛋白Notch1。实验发现Notch1在肿瘤组织中的表达是上调的，这与miR-139-5p的表达负相关。体内外实验证明miR-139-5p通过下调NOTCH1表达逆转CD133+/CD44+相关的MDR。在CRC细胞系中，通过回补实验证明过表达NOTCH1可以削弱miR-139-5p对多药耐药的抑制效果。因此该课题的研究成果可总结为miR-139-5p通过下调NOTCH1信号通路来逆转CD133+/CD44+相关的结肠癌细胞多药耐药表型。本课题为miR-139-5p作为结肠癌肿瘤干细胞和多药耐药指示分子及其药物治疗的药效学观察指标提供了理论依据。