长链非编码RNA LINC01996 同时维持PTEN的蛋白活性和稳定性从而抑制肺癌发生发展的作用与机制研究

We previously reported that tumor suppressor gene PTEN was importantly regulated by several miRNAs at the post-transcriptional level. For its post-translational modulation manner, PTEN phosphorylation and stabilization are also very important. Interestingly, it has been well-acknownledged that phosphorylation of PTEN on multiple residues promotes PTEN protein stability whereas adversely inhibits its phosphatase activity. Considering its great tumor suppressive roles, especially in normal cells, it is quite likely that there are underlying mechanisms simultaneously maintaining PTEN activity and stability. However, the crucial relevant molecules are lack of study. Recently, long non-coding RNAs (lncRNAs) have obtained much attention and investigation. During our preliminary experiments using high-throught RNA sequencing technology, LINC01996, which was validated to be downregulated in lung cancer tissue, was found to potentially bind PTEN and is large likely to simultaneously maintain PTEN activity and stability. Silencing LINC01996 significantly suppressed lung cancer cell growth and invasion, and cooperated with oncogenic HRasV12 to overcome cellular senescence. Interestingly, stimulation of pro-inflammation cytokines IL6 and TNFα markedly inhibited expression of LINC01996. Based on these results, this project is going to systemically clarify the potential tumor suppressive function of LINC01996 in lung cancer, the detailed mechanisms underlying its simultaneous modulation on PTEN activity and stability and its regulation by inflammatory pathways, as well as its clinical significance for lung cancer patients, which would shed bright light on the important events during lung carcinogenesis and provide novel therapeutic targets for anti-lung cancer treatment.

我们已报道抑癌基因PTEN在转录后受到多个miRNA的重要调控。在翻译后PTEN蛋白的磷酸化和稳定性调控尤为重要。有意思的是，PTEN蛋白多个位点的磷酸化促进其稳定性却让其失活或增加活性却使其不稳定。鉴于PTEN的抗癌作用，极大可能存在同时保持PTEN活性和稳定性的调控机制，但关键分子知之甚少。近年来长链非编码RNA（lncRNA）成为研究热点。我们预实验通过RNA-Seq筛选出了在肺癌组织中表达下调的LINC01996与PTEN结合，并同时维持PTEN活性和稳定性。沉默LINC01996抑制肺癌细胞生长和侵袭，并协同HRasV12克服细胞衰老。炎性因子IL6和TNFα共刺激则抑制LINC01996表达。在此基础上，本项目将系统性研究LINC01996在肺癌中的抑癌作用、同时维持PTEN活性和稳定性的具体机制、下游炎症调控机制及临床意义，从而阐明肺癌发生发展的过程，为肺癌诊治提供新靶点。

由于对肺癌发生发展的机制缺乏充分了解，肺癌的早期诊断缺乏重要的预警分子。目前手术、放疗及化疗等常规治疗技术的治疗结果尚难以令人满意，新的潜在治疗靶点仍然有待发掘。因此，揭示肺癌发生发展过程中的重大事件，阐明肺癌发生发展的分子机制，是目前肺癌研究中非常迫切的任务。本项目经过一系列研究，主要取得了如下科学发现：1）阐明了关键抑癌基因PTEN同时保持足够的蛋白量和活性从而行驶强有力地抑癌作用的新机制，解析了Atg7作为抑癌蛋白FOXO3a的功能性下游基因在保护细胞避免发生恶变转化中的重要作用，拮抗CK1α诱导的细胞自噬促使肺上皮细胞逃逸癌基因Ras诱导的细胞衰并发生恶性转化，揭示了细胞衰老效应中表现出空泡状结构的生物学过程和调控机制，阐明了细胞自噬在细胞衰老效应中的重要性；2）阐明了AKT促进非EMT形式的肺腺癌转移的新过程与新机制，揭示了Vimentin不仅可以作为EMT的蛋白标志物，同时具有促进非EMT形式的肿瘤转移的生物学作用；3）发现了肺癌中促癌基因RFC4的异常扩增有望作为肺癌诊治的靶点，揭示了Notch信号通路的在肺癌中异常激活的新机制，为靶向Notch的肿瘤治疗策略改进提供了理论依据，提出RFC4有望成为提高Notch通路抑制剂疗效的新靶标分子；4）发现转录因子ATOH8通过与SMAD3结合阻断TGF-β介导的癌基因Ras诱导的细胞衰老和恶性转化，发现了一个新的潜在抑癌基因即ATOH8，揭示了上皮细胞中癌基因诱导衰老的新机制，阐明TGF-β/SMAD3通路在细胞衰老与恶性转化中的转变作用，为Ras突变型肿瘤的诊治提供新的靶点和策略。项目执行以来，已在NAT CELL BIOL （1篇），NAT COMMUN（2篇），Oncogene（1篇）和Cell Biosci（1篇）等高水平国际学术期刊上发表了5篇SCI文章。此外，项目负责人以第二完成人获得2020年度广东省自然科学奖一等奖。参与培养8名博士/硕士毕业研究生。