SETD1A通过NEAT1/Wnt/β-catenin正反馈环路调控肺腺癌细胞干性及化疗敏感性的研究

Lung adenocarcinoma is the most prevalent lung cancer. Cancer stem cells play an important role in chemotherapy response. However, the mechanism of maintaining cancer stem cell property remains largely unclear. In the pre-experiment, we found that SETD1A expression was increased in lung adenocarcinoma stem cells compared with normal lung adenocarcinoma cells. SETD1A knockdown inhibited the self-renewal ability of lung adenocarcinoma stem cells, and increased the sensitivity of lung adenocarcinoma cells to cisplatin. Furthermore, we identified that NEAT1 levels were reduced following SETD1A knockdown, while Axin2 levels were elevated. In addition, β-catenin depletion significantly inhibited NEAT1 expression. Combined with recent references, we hypothesized that: SETD1A could be recruited to the NEAT1 promoter by OCT4 and promote NEAT1 transcription by inducing H3K4 trimethylation. Subsequently, NEAT1 could active Wnt/β-catenin pathway through inhibiting Axin2 expression, and thereby regulate lung adenocarcinoma stem cell property and chemotherapy sensitivity. In turn, Wnt pathway could elevate NEAT1 levels via increasing OCT4 expression and form a positive feedback loop of OCT4/NEAT1/Axin2/β-catenin. To test the hypothesis in this project, we plan to elucidate the mechanisam of SETD1A in regulating lung adenocarcinoma stem cell property and chemotherapy sensitivity by using sphere formation assay, chromatin immunoprecipitation assay and luciferase reporter gene assay. This project is expected to provide new thoughts for the chemosensitization of lung adenocarcinoma.

肺腺癌是最常见的肺癌类型，肿瘤干细胞是导致化疗失败的重要原因。前期研究中，我们发现肺腺癌干细胞中SETD1A表达上调，SETD1A敲减抑制肺腺癌干细胞自我更新能力，增强顺铂化疗敏感性，伴随着NEAT1表达下调及Axin2表达上调；而β-catenin敲减可下调NEAT1表达。结合文献及生物信息分析，我们提出假说：肺腺癌细胞中SETD1A可被OCT4募集至NEAT1启动子，促进H3K4三甲基化激活NEAT1转录，NEAT1通过抑制Axin2激活Wnt通路以调控肺腺癌干细胞特性及化疗敏感性；Wnt通路通过上调OCT4促进NEAT1表达形成OCT4/NEAT1/Axin2/β-catenin正反馈环路。本项目拟以球体形成实验、染色质免疫共沉淀、荧光素酶报告实验等方法深入探讨SETD1A通过NEAT1/Axin2轴激活Wnt/β-catenin通路相关机制，为肺腺癌干细胞研究及化疗增敏提供新思路。

肺癌是最常见的恶性肿瘤之一。近年来，由于分子靶向治疗和免疫治疗的广泛应用，非小细胞肺癌的治疗取得了长足的进展;然而，肺癌的5年生存率仍不足20%。因此，进一步研究NSCLC发生和发展的潜在机制仍然是迫切的临床需求。SETD1A催化H3K4到H3K4me3，而H3K4me3通常在转录起始位点富集以激活基因转录。同时SETD1A参与干细胞的多能性和恶性转化。本项目主要对SETD1A进行临床数据分析，体外实验以及体内实验三个部分的研究。发现SETD1A在NSCLC中表达明显增高，其过表达预示着NSCLC患者预后不良。功能实验发现，SETD1A通过Wnt/β-catenin通路正向调控NSCLC细胞的癌干细胞特性，负向调控顺铂敏感性。接下来发现SETD1A通过与β-catenin相互作用并稳定β-catenin，正向调控Wnt/β-catenin通路。SET结构域在SETD1A与β-catenin的相互作用中是不可或缺的。此外，发现SETD1A结合NEAT1和EZH2的启动子，通过诱导H3K4me3富集激活基因转录。抢救实验表明，SETD1A促进Wnt/β-catenin通路并在NSCLC中发挥其致癌功能，至少部分是通过上调NEAT1和EZH2来实现的。此外，SETD1A被证明是Wnt/β-catenin通路的直接靶点，从而在NSCLC细胞中形成正反馈环路，协同促进NSCLC的进展。基于本研究，可能会确定新的预后因素和治疗靶点，有助于改善NSCLC患者的诊断和预后。