干细胞标记物基因 Musashi1 rs2522137位点单核甘酸多态性与肺癌关系的研究

Musashi RNA-binding protein 1 (Musashi-1，Msi1), an RNA-binding protein, is expressed in various epithelial stem cells and plays an important role in regulating the maintenance and differentiation of stem/precursor cells. Msi1 is over-expressed in several tumor tissues including lung cancer, suggesting a correlation with oncogenic development.Our pilot study provides the first evidence to correlate the Musashi-1 rs2522137 SNP variant with lung cancer. Currently, we know very little about the detailed molecular mechanisms by which Musashi-1 rs2522137 polymorphisms contribute to lung cancer development. The 3’-UTR of mature Musashi-1mRNA is potentially targeted by several tumor suppressor miRNAs andevolutionarily conserved RNA-binding protein. Using the SNPinfo website(http:// snpinfo. niehs. nih.gov/), we found that the Musashi-13’-UTR also buries potential target sites for miRNAs hsa-miR-1275, hsa-miR-1285, hsa-miR-483-5p.,hsa-miR-486-3p, hsa-miR-612, and hsa-miR-625. It is worthwhile noting that Musashi-1 rs2522137 is located within these miRNA binding sites. we thus propose to characterize the role of rs2522137genotype in determining the stability of Msi1 mRNA, thus the stemness and self-renewal of lung cancer stem cells. We will fucos on the epigeneticmechanisms by which Musashi-1 rs2522137 GG variant affects its own mRNA expression through the microRNA pathway. The data obtained from this study will shed light on the molecular mechanisms for the regulation of the Msi1 in lung cancer. In addition, this project will provide a mechanistic rationale for designing antitumor drugs that target the overexpressed Msi1 in lung stem cancer cells.

Musashi1 (Msi1)是最新研究报道的肿瘤干细胞标志物之一，在肺癌及多种肿瘤中高表达，与肿瘤的发生、预后治疗相关，但其高表达的具体机制尚不清。本课题组在国际上首次发现位于Msi1基因3’非翻译区的rs2522137 单核甘酸多态性（SNP）是肺癌发病的独立危险因素，且与晚期非小细胞肺癌的预后相关。进一步的功能分析提示rs2522137位于6个不同miRNA结合位点的重叠区。因此rs2522137 SNP可能通过表观遗传学机制（miRNA）调控Msi1在肿瘤中的差异性表达及Msi1 mRNA的稳定性,从而影响肺癌干细胞的干性，增加肺癌发病危险。本课题将分析Msi1基因rs2522137与肺癌易感及预后的关系，探索该位点不同基因型在不同肺癌细胞系及组织样本中的Msi1表达的差异，阐明rs2522137调控Msi1表达的表观遗传学机制，最终为肿瘤的临床靶向治疗提供依据。

肿瘤干细胞是近年来肿瘤研究领域的一个新热点，肺癌干细胞（lung cancer stem cell, LCSC）是指肺癌组织中一部分具备自我更新和增殖分化能力、致瘤性较强、并具有特异性标记物的细胞群。它们在肺癌的发生、发展、侵袭、转移、复发以及抗辐射和耐药性获得起至关重要的作用。近年来多种肺癌干细胞标记物相继被发现和报道，包括CD133、MSI1、ALDH1、EpCAM、Bmi-1、OCT-4、甘氨酸脱氢酶（glycine dehydrogenase, GLDC）、SHH及CTNNB1等[236-244]。目前尚无针对该部分基因SNP与肺癌易感性的报道，本研究首次发现位于MSI1基因 3’ 非翻译区的rs2522137位点的基因型GG是肺癌发病的危险因素，而SHH基因rs1233560位点T/C和T/T基因型是肺癌的保护因素。此外，在多因素模型中， CTNNB1基因的rs1798802位点的A allele与男性人群肺癌发病风险增加相关，rs2522137位点的基因型GG仍与肺癌的发病风险增加相关。本研究所建立的肺癌风险预测模型适用于中国东北地区的人群。研究中纳入了许多新的预测因素例如杀虫剂的暴露史、肺结核病史，油烟暴露史及饮食因素等，故所建立的模型的预测效果较好，纳入SNP的模型的AUC为0.8703，能够较好的区分肺癌高危与低危人群。这个模型有助于临床医师早期发现肺癌的高危患者，对其进行戒烟及生活习惯等方面的指导，有助于降低肺癌的发病率提高社区人群的保健意识。将对控制和降低我国肺癌的发病率具有重要意义。