胰腺癌细胞中PNKP基因转录的调控机制及其意义

Pancreatic cancer grows fast and has high malignancy. The effective drug to treat the disease is absent at present. It is difficult problems how to effectively control pancreatic cancer cell growth and selectively induce cancer cell apoptosis. We recently found that polynucleotide-5’kinase-3’phosphatase (PNKP) was aberrant lowly expressed in the tumor tissue of the pancreatic cancer patients, and that the expression levels of PNKP were related to the survival or dearth of pancreatic cancer cells. Further reduction of PNKP gene expression levels with triptonide, a monomer derived from the traditional Chinese medicinal herbal, selectively induced pancreatic cancer cell apoptosis, and exhibited excellent anti-pancreatic cancer effect without obvious toxicity and complications. Whereas, why PNKP is aberrant lowly expressed in pancreatic cancer? How to eliminate pancreatic cancer cells through down-regulateion of PNKP expression levels? These two scientific questions remain to be solved. In this research project, we will perform studies as following two aspects: (1) we will study the regulatory mechanism of PNKP gene transcription in pancreatic cancer cells by gene promoter DNA methylation, histone acylation, transcription factors, and signal transduction pathways; (2) we will elucidate the mechanisms of triptonide and other important intracellular and extracellular factors to regulate PNKP gene transcription in pancreatic cancer cells，and evaluate the significance of triptonide in pancereatic cancer therapy. Accordingly, we will take PNKP as the core to develop new strategies and methods for anti-pancreatic cancer therapy.

胰腺癌生长快、恶性高，目前尚无有效的治疗药物。如何有效地控制胰腺癌细胞增殖和选择性诱导癌细胞凋亡是胰腺癌治疗难题。最近申请人发现，多聚核苷酸-5’激酶-3’磷酸酶（PNKP）基因在人胰腺癌组织呈低表达，其表达水平高低与胰腺癌细胞生死攸关；用中草药单体雷公藤内酯酮进一步降低细胞内PNKP基因表达水平，能选择性诱导胰腺癌细胞凋亡, 在小鼠体内取得很好的抗胰腺癌效果，且无明显毒副作用。然而，为什么PNKP基因在胰腺癌细胞中低表达？如何通过下调PNKP基因表达水平来消除胰腺癌细胞？是亟需解决的科学问题。申请人将进行两个方面研究:（1）研究胰腺癌细胞中PNKP基因启动子DNA甲基化、组蛋白乙酰化、转录因子及信号通路对PNKP基因转录的调控机制；（2）阐明雷公藤内酯酮等细胞内外重要因素对PNKP基因转录的调控机理，并评估雷公藤内酯酮对胰腺癌治疗的意义。据此，制定以PNKP为核心的抗胰腺癌新策略和方法。

项目的背景: 胰腺癌恶性高，目前尚无有效治疗药物。最近申请人发现，多聚核苷酸-5’激酶-3’磷酸酶（ PNKP）在人胰腺癌组织呈低表达，PNKP对胰腺癌的作用未见报道。PNKP基因在胰腺癌细胞中低表达的机制和意义有待于研究。.主要研究内容: 申请人进行两个方面研究:（1）研究胰腺癌细胞中PNKP基因启动子激活和基因转录的调控机制；（2）阐明PNKP基因转录的调控机理和对胰腺癌诊断与治疗的意义。.重要结果和关键数据：申请人发现PNKP基因在胰腺癌病人肿瘤组织和细胞中低表达。进一步研究发现，调控PNKP基因转录的两个上游转录因子LXRα和SREBF1表达水平都低表达，从而导致PNKP基因转录降低。LXRα、SREBF1和PNKP表达降低导致胰腺癌细胞DNA修复缺陷，DNA链断裂数量增高，基因组不稳定。我们通过一系列深入研究，在国内外发现一条新的LXRα-SREBF1-PNKP1信号通路,该通路在调控胰腺癌细胞DNA修复起了重要作用，揭示了胰腺癌DNA修复缺陷的新机制。此外，申请人发现中草药单体雷公藤内酯酮能够与其受体蛋白LXRα直接结合，使LXRα蛋白失活，从而降低胰腺癌细胞内PNKP基因表达水平，选择性诱导胰腺癌细胞有丝分裂灾难和凋亡。 在小鼠体内雷公藤内酯酮具有很强的抗胰腺癌效果，且无明显毒副作用。在荷瘤小鼠体内雷公藤内酯酮具有很强的抗胰腺癌效果，且无明显毒副作用。这些创新性研究成果已发布在Cell Death Differ. 2020 Aug;27(8):2433-2450 [SCI一区，IF=14.3]，并已获得国际PCT发明专利授权(申请人：周泉生，曹志飞，授权时间：2019年3月2日，专利号PCT/CN2017/106309).项目的科学意义：本研究项目揭示了胰腺癌DNA修复缺陷的分子机制，为胰腺癌的靶向治疗找到了新的分子靶标，为抗胰腺癌新药研发提供了新的平台，对控制肿瘤细胞DNA修复和胰腺癌靶向治疗具有重要意义。