circ_1483通过募集let_7c解除胃癌组织中胃粘膜分化抗原PGC表达沉默的分子机制研究

Pepsinogen C (PGC) is a biomarker for mature differentiation of gastric mucosa cells, the absence of which shows significant relation with gastric cancer. However, the regulating mechanism remains unclear. We found in our previous study that PGC gene is the target for miRNA let_7c; circ_1483 might target let_7c and related with PGC gene expression; PGC and circ_1483 were synergistically expressed in gastric cancer tissue, both of which demonstrated reverse expression tendency with let_7c. On the basis of this, we hypothesize that the silenced expression of PGC might be attributed to competitive combination of circ_1483 with let_7c. This project aimed to clarify in vivo and in vitro whether let_7c could cause silencing of PGC expression in gastric tissue? Whether circ_1483 could up-regulate PGC expression by recruiting let_7c? Whether circ_1483-let_7c-PGC pathway participate in gastric carcinogenesis? It is anticipated to unravel the mechanism of the silenced expression of gastric mucosa differentiation antigen PGC regulated by circ_1483-let_7c pathway.

胃蛋白酶原C(PGC)是胃粘膜细胞分化成熟的标志性蛋白，其表达缺失与胃癌显著相关，但调控机制尚不清楚。我们前期发现PGC基因是let_7c的靶标；环状RNAcirc_1483可能与let_7c互为靶标且与PGC基因表达相关；PGC与circ_1483在胃癌组织呈同向表达趋势，而两者均与let_7c呈反向表达趋势。据此推测PGC在胃癌组织表达沉默可能以circ_1483与PGC竞争性结合let_7c为基础。本研究进一步采用细胞培养、实验动物及人体组织标本，从体内外多角度探索let_7c是否可以引起胃癌组织中PGC表达沉默？circ_1483是否可以募集let_7c并籍此上调PGC？circ_1483-let_7c-PGC通路是否参与胃癌发生？以期最终阐明基于circ_1483-let_7c通路调控的胃粘膜分化抗原PGC在胃癌组织中表达沉默的分子机制。

正常细胞分化抗原的缺失是恶性肿瘤显著特征之一。深入研究肿瘤细胞分化抗原的表达沉默机制，有助于从去分化角度解析肿瘤的发生机制以及从诱导分化的角度寻找肿瘤治疗的分子靶点。胃蛋白酶原C(Pepsinogen C，PGC)是胃粘膜细胞分化成熟的标志性蛋白，其表达缺失与胃癌风险显著相关。目前PGC基因的功能及其在胃癌组织中表达沉默的分子调控机制尚不清楚。本项目采用细胞培养、实验动物模型和人体组织标本以及多种实验技术，深入探索PGC的功能并从非编码RNA调控角度探讨了circ_1483通过募集let_7c调控PGC表达以及circ_1483-let_7c-PGC通路参与胃癌发生的作用机制。研究结果显示：PGC可以抑制胃癌细胞增殖及迁移，上调胃癌细胞成熟分化指标表达，抑制干性指标表达，对胃癌细胞凋亡未见明显影响；let_7c与PGC可以特异性结合，circ_1483与let_7c可以特异性结合， circ_1483-let_7c轴调控下游PGC表达进而影响胃癌细胞增殖、迁移、分化等生物学行为。本研究证实胃粘膜分化抗原PGC在胃癌组织表达沉默的分子机制之一是以circ_1483与PGC竞争性结合let_7c为基础，circ_1483通过募集let_7c，可以解除其抑制PGC表达的作用，上调PGC表达，降低胃癌发生风险。 .本项目有助于深入理解非编码RNA转录后调控作用机制；有助于深入理解以胃黏膜分化标志物PGC基因为核心，circRNA通过miRNA介导调控PGC基因表达参与胃癌发生的分子机制，有助于从去分化角度解析肿瘤的重编程机制以及从诱导分化的角度寻找胃癌治疗新的分子靶点。