LncRNA-GC1竞争性结合miR-551b-3p上调dysbindin表达促进胃癌化疗耐药的分子机制研究

Chemo-resistance is one of the important causes of poor prognosis of gastric cancer patients, but the exact mechanism is still not very clear. The regulation of lncRNA and miRNA and its downstream target genes has become in focus of the field. Our previous study has shown that: ① lncRNA-GC1 is over-expressed and miR-551b-3p is under-expressed in chemo-resistant gastric cancer cells and tissues, and it is predicted for potential binding sites between the two molecules; ② dysbindin is elevated in drug-resistant tissues of gastric cancer. It can also promote chemoresistance of gastric cancer cells, and its non-coding region has a specific binding effect with miR-551b-3p. These results strongly suggest that lncRNA-GC1 and miR-551b-3p may play an important regulatory role in the expression of dysbindin and play a role in regulating the drug resistance of gastric cancer cells. Based on this, the project is intended to solve the following problems from four levels of molecular, cellular, animal and clinical samples: ① the abnormal expression and clinical significance of three molecules in gastric cancer resistant tissues; ② lncRNA-GC1 and miR-551b -3p specific binding site and regulatory relationship. Based on the new regulation mode of ceRNA, this study will provide a new understanding of the comprehensive understanding of gastric cancer chemotherapy resistance.

化疗耐药是胃癌患者预后较差的重要原因，但其机制仍不十分明确。新近研究表明lncRNA可作为ceRNA竞争结合miRNA促进肿瘤化疗耐药。我们前期发现：①胃癌耐药细胞和组织中lncRNA-GC1表达上调，而miR-551b-3p表达下调，软件提示二者存在结合位点；②dysbindin在耐药组织中高表达并促进胃癌细胞化疗耐药，其非编码区与miR-551b-3p存在特异性结合作用。这些强烈提示lncRNA-GC1和miR-551b-3p可能作为dysbindin表达的重要调节分子，发挥调控胃癌细胞耐药性的功能。基于此，本项目拟从分子、细胞、动物及临床样本四个层次，明确如下问题：①三种分子在胃癌中的异常表达及临床意义；②lncRNA-GC1与miR-551b-3p的特异性结合位点及调控关系。本研究将立足于ceRNA这一新的调控模式，为全面认识胃癌化疗耐药提供新的视角。

在全球范围内，每年约有120万人被新确诊为胃癌，同时每年有至少60万人死于该疾病。由于缺乏特异性的临床症状和相应的早期诊断手段，多数胃癌患者就诊时已为中晚期（局部进展或远处转移）。因此，以铂类为主的联合化疗在胃癌综合治疗中就占有重要的地位。然后，化疗耐药仍是目前导致胃癌患者预后较差的重要原因，但其机制仍不十分明确。现有的研究发现：ceRNA调控模式在其中发挥重要作用。我们课题组结合前期研究基础提出：胃癌细胞中高表达的 lncRNA-GC1 通过竞争性结合 miR-551b-3p，使得与dysbindin mRNA结合的miR-551b-3p下降，进而上调dysbindin表达，最终促进胃癌化疗耐药。针对这一科学问题，我们依托多种胃癌耐药细胞系，利用RNA-seq、Chip-PCR、免疫共沉淀等技术，发现：①胃癌耐药细胞和组织中lncRNA-GC1和dysbindin表达显著上调，二者显著关联于患者预后；②miR-551b-3p可与dysbindin mRNA特异性结合，进而负性调控dysbindin蛋白水平，促进胃癌细胞耐药；③lncRNA-GC1可通过sponge机制海绵样吸附miR-551b-3p，从而达到调控dysbindin表达的作用，最终促进胃癌细胞铂耐药。另外，我们创新性的发现lncRNA-GC1可被包裹进循环外泌体，循环外泌体lncRNA-GC1可作为胃癌患者早期诊断和疾病进展检测的血清学指标。本项目立足于ceRNA这一新的调控模式，为全面认识胃癌化疗耐药提供了新的视角和潜在干预靶点。