长链非编码RNA PRL-3-AS介导胃癌基因PRL-3的选择性启动子激活的 分子机制研究

PRL-3 is closely related to tumor metastasis. We have previously confirmed that PRL-3 is overexpressed in gastric cancer and promotes the peritoneal metastasis of gastric cancer through PI3K/Akt signaling pathway. However, the transcriptional regulation mechanism of PRL-3 high expression in gastric cancer is unknown. In the preliminary experiment, we found that PRL-3 oncoprotein have two transcripts subtype with independent promoter, in which PTP4A3-201 promoter constantly activate, while the PTP4A3-001 promoter is only activated in gastric cancer, this activation seems to be closely associated with methylation and antisense lncRNA PRL-3-AS. We tentative predict PRL-3 may bind to the methylated enzymes and regulate the PTP4A3-001 expression but not the PTP4A3-201 expression. We hypothesized that PRL-3-AS binds and recruits the methylated enzymes to the promoter region of PTP4A3-001 to induce methylation to determine the activity of the promoter. Firstly, in this study, we hope to confirme that the high expression of PRL-3 in gastric cancer is induced by the activation of PTP4A3-001 promoter methylation but not the PTP4A3-201. Secondly, we will make further investigation that PRL-3-AS may cobimned with methylase to PTP4A3-001 promoter region which is the main mechanism leading to methylation alteration. The results of this study will provide a new therapeutic target for gastric cancer metastasis.

PRL-3与癌转移密切相关，之前我们证实PRL-3在胃癌中过表达并通过PI3K通路促进胃癌腹膜转移，但导致胃癌中PRL-3过表达的转录调控机制尚不清楚。近来我们发现PRL-3促癌蛋白亚型存在拥有独立启动子的两个转录本，其中PTP4A3-201的启动子恒定活化，而PTP4A3-001的仅在胃癌中被激活，其激活与启动子甲基化和反义lncRNA PRL-3-AS具有关联性；初步预测PRL-3-AS可结合甲基化相关酶和改变PTP4A3-001而非201表达。由此建立了PRL-3-AS结合并招募甲基化酶到PTP4A3-001的启动子区并进而诱导甲基化改变和转录激活的假说。为此本研究拟先证实胃癌中PRL-3的高表达由PTP4A3-001而非201的启动子甲基化改变导致，进一步证实PRL-3-AS结合甲基化酶到PTP4A3-001的启动子区是导致甲基化改变的深层机制。本研究将为胃癌转移提供新的治疗靶点。

肝再生磷酸酶3（PRL-3）属于蛋白酪氨酸磷酸酶超家族，诱导肿瘤相关蛋白磷酸化，活化信号通路促进肿瘤增殖、转移。在前期工作中，我们证实了PRL-3通过活化PI3K/Akt/NF-κB信号通路，上调MMP-2、MMP-9的表达，促胃癌腹膜转移。但是PRL-3的上游表达调控机制及耐药机制尚未阐明。在本项研究中，我们探讨了调控PRL-3表达的双重作用机制。首先，我们探讨了非编码RNA lncRNA PRL-3-AS可以吸附在PTP4A3-001启动子区，负性靶向调控PRL-3表达，进一步调节PI3K/Akt信号通路，抑制胃癌的生物学功能。随后，发现非编码RNA lncRNA UCA1在胃癌中高表达，并证明了lncRNA UCA1可以通过海绵化MicroRNA-495从而调控PRL-3表达促进胃癌进展。其次，在探讨胃癌耐药机制中，我们探讨了胃癌耐药相关的lncRNA在胃癌患者预后评估中的作用，并进一步证实了lnc00106和UBE2R2-AS1在胃癌中低表达，并且更容易发生耐药，敲除lnc00106和UBE2R2-AS1非编码RNA能进一步促进胃癌的增殖、转移；同时我们也证实了胃癌中的PRL-3基因可以通过激活PI3K/Akt-Nrf2信号通路进一步调节胃癌耐药细胞的增殖和耐药。本项目进一步了阐明PRL-3的上游调控机制和PRL-3在胃癌耐药的作用，为胃癌的防治提供了新的理论支撑和干预环节，具有一定的科学意义和应用价值。