从调控miR-205及其靶点角度探讨二氢青蒿素抗胰腺癌作用机制

Pancreatic cancer is an extremely malignant disease with dismal prognosis, that lack of effective therapeutic strategy. We first confirmed that anti-malaria drugs dihydroartemisinin has anticancer effects on pancreatic cancer in vitro and in vivo, but the precisely mechanisms implicated need further investigation. It has not been reported that whether dihydroartemisinin exerts anticancer effects by regulating microRNA's expression. Based on the results we just obtained from a microRNA array analysis of differentially expressed microRNAs in dihydroartemisinin treated pancreatic cancer cells, we hypothesize that dihydroartemisinin downregulates the expression of miR-205, which targeting PTEN to inhibit the PI3K/Akt signal pathway, thus inhibiting the activation of NF-κB in pancreatic cancer to exert its anticancer effect. In this study, we will transfect miR-205 mimics to make it overexpression and transfect miR-205 antagnomirs to repress its expression in pancreatic cancer cells, the changes of the anticancer effects of dihydroartemisinin, the expression of PTEN in the level of mRNA and protein, also the activity of PI3K/Akt pathway and NF-κB will detected. In addition, luciferase reporter system will be used to further validate the targets of miR-205. This study has the value to thoroughly understand mechanisms of anticancer effects of dihydroartemisinin, settle the basement of its clinical application, that also maybe helpful to establish a new target for the treatment of pancreatic cancer.

胰腺癌恶性程度高，预后差，缺乏有效的治疗手段。我们于国内外率先证实，抗疟药二氢青蒿素在体外、体内具抗胰腺癌作用，但具体机制仍不明确，其是否通过调控microRNA的表达而发挥抗肿瘤作用尚未见文献报道。本课题在前期研究基础上，提出二氢青蒿素下调miR-205的表达，靶向PTEN，抑制PI3K/Akt信号通路，抑制NF-κB活化而发挥抗胰腺癌作用这一假说。本课题在体外、体内转入miR-205 mimics和miR-205 antagomirs以达到miR-205过表达及表达抑制的目的，检测二氢青蒿素抗胰腺癌作用、PTEN表达、PI3K/Akt及NFκB活性。本课题具有源头理论创新性及重要的实际应用价值。本课题的实施，对深入理解二氢青蒿素抗肿瘤作用机制具有重要价值，为其临床应用奠定基础，同时可为胰腺癌的治疗开辟新的路径和靶点。

胰腺癌是恶性程度高且致死率高的癌症之一。虽然胰腺癌患者经历了复杂的手术和系统的化疗，其5年生存率仍然低于8%。因此寻找新的预防和治疗胰腺癌的方案便显得尤为迫切。二氢青蒿素为青蒿素的衍生物和主要活性代谢产物，为一种十分有效的抗疟疾药物。二氢青蒿素已经被证明在多种癌症中如胰腺癌、肺癌、乳腺癌、宫颈癌和黑色素瘤具有抗肿瘤作用。在前期实验中已经证实二氢青蒿素通过抑制NF-κB进入细胞核并下调其下游基因产物而在体内、体外发挥抗胰腺癌作用。MicroRNA是一类非编码单链小分子RNA，通过特异性碱基配对与相应的靶mRNA 的3'非编码区结合，降解mRNA或阻碍其翻译，在转录后水平调节其靶mRNA的基因表达。近年的实验及临床研究表明microRNA的异常表达与肿瘤的发生和发展进程关系密切。有鉴于此，我们提出假说：二氢青蒿素通过调控microRNA的表达而发挥抗胰腺癌作用。我们采用microRNA芯片技术筛选出受二氢青蒿素调控的microRNA。在实验研究中我们得出结果证实二氢青蒿素通过下调miR-205的表达而靶向调控PTEN基因发挥抗胰腺癌作用。在深入挖掘microRNA芯片数据和系统的实验研究后，我们还证实二氢青蒿素通过上调miR-30c-5p、miR-130b-3p、miR-34a-5p和miR-195-5p靶向下调Cdk4、Cdk6、E2F1、E2F3、CDC42、IKKα、Rac1、MEK1和VEGF的mRNA表达水平组成microRNA-mRNA的调控网络而发挥抗胰腺癌作用。本研究在前期工作的基础上，深入研究了二氢青蒿素抗胰腺癌的机制。希望研究成果早日应用于临床，提高胰腺癌的生存率。