长链非编码RNA在二氢青蒿素逆转胰腺癌化疗耐药中的作用及其机制研究

Resistance to chemotherapy is a major cause of treatment failure in pancreatic cancer. Our previous studies showed that dihydroartemisinin could obviously inhibit the proliferation of pancreatic cancer cells and inhibit the growth of pancreatic cancer xenograft tumor in nude mice, moreover, it could sensitize the antitumor effect of gemcitabine in pancreatic cancer, but its mechanism of action is not yet fully elucidated. In recent years, more and more attention have been paid to the regulatory effects of long non-coding RNA on gene expression. This project will try to investigate the possible mechanism by which dihydroartemisinin reverts gemcitabine resistance in pancreatic cancer from this new perspective. We will choose two gemcitabine-resistant pancreatic cancer cell lines for the study and utilize lncRNA Microarray and Bioinformatics to detect key lncRNA that are associated with dihydroartemisinin-mediated reversal of gemcitabine resistance in pancreatic cancer and then take advantage of gene-expression microarrays and RNA interferences in vitro and in vivo to explore the role and potential mechanism of lncRNA in dihydroartemisinin-mediated reversal of gemcitabine resistance in pancreatic cancer. This project will elucidate the role and potential mechanism of lncRNA in dihydroartemisinin-mediated reversal of gemcitabine resistance in pancreatic cancer, providing new targets for the treatment of gemcitabine-resistant pancreatic cancer; furthermore, it will enlighten new ideas for exploring the mechanism of action of dihydroartemisinin and provide more sufficient scientific evidence for its further development and utilization.

化疗耐药是胰腺癌治疗失败的主要原因之一。我们前期研究证实，二氢青蒿素可显著抑制胰腺癌细胞的增殖及裸鼠胰腺癌移植瘤的生长，并可增敏吉西他滨抗胰腺癌的作用，但其作用机制尚未完全阐明。近年来，长链非编码 RNA对基因表达的调控作用日益受到重视。本课题尝试从这一崭新视角研究二氢青蒿素逆转胰腺癌吉西他滨耐药的可能机制。本项目拟以胰腺癌吉西他滨耐药细胞株为研究对象，采用 lncRNA 芯片和生物信息学等手段鉴定与二氢青蒿素逆转胰腺癌吉西他滨耐药相关的关键性 lncRNA，然后通过基因克隆和RNA 干扰等技术在细胞和动物模型中探讨关键性 lncRNA 在二氢青蒿素逆转胰腺癌吉西他滨耐药中的作用及调控机制。本项目将阐明 lncRNA 在二氢青蒿素逆转胰腺癌化疗耐药中的作用及机制，为针对胰腺癌耐药的治疗提供新的靶点，并开辟二氢青蒿素作用机制研究新的思路，为其进一步开发利用提供更充分的科学依据。

胰腺癌是消化系统常见恶性肿瘤之一，其临床表现隐匿，病情进展快，恶性程度高，预后差。对于胰腺癌的诊断与治疗，尚无明确的特异性分子指标以及药物干预的靶点，长链非编码 RNA（long non-coding RNA，lncRNA）是一类转录本长度超过 200nt的非编码 RNA分子，其在肿瘤的的发生、发展以及化疗敏感性调控中发挥着十分重要的作用。自噬作为细胞的一种自我保护机制，在肿瘤发生发展中扮演重要角色，本研究旨在探讨MALAT1通过激活胰腺癌细胞自噬，参与胰腺癌增殖、侵袭及转移的分子机制。试图找出利于胰腺癌诊治的相关指标，为提高胰腺癌的诊治、改善患者预后，提供一定的借鉴与参考。我们的研究发现：（1）MALAT1在胰腺导管腺癌组织及多数胰腺癌细胞系中呈现高表达，对于MALAT1高表达的病人，其预后相对较差。多因素回归分析显示，组织中MAlAT1表达水平高低可作为评价胰腺癌病人预后的独立影响因素；（2）与正常胰腺组织相比，肿瘤组织中自噬水平显著升高，并且，MALAT1表达与LC3B mRNA水平呈显著正相关；（3）沉默胰腺癌细胞株中MALAT1的表达水平，可直接抑制细胞自噬水平，进一步研究提示，MALAT1对自噬的抑制作用主要体现在其干扰自噬体与溶酶体的融合；（4）MALAT1可以与RNA结合蛋白HuR靶向结合，沉默MALAT1能够抑制细胞内HuR表达；（5）细胞内HuR与TIA-1可形成复合体，MALAT1通过靶向结合HuR，降低其表达水平，但并不影响TIA-1蛋白表达，通过对TIA-1转录后修饰，进而改变TIA-1的功能，实现对细胞自噬水平的调控；（6）沉默MALAT1能够降低细胞自噬水平，同时，也能够抑制肿瘤细胞增殖、侵袭与转移，进一步研究证实，MALAT1通过激活自噬促进进肿瘤增殖、侵袭及转移；（7）胰腺癌原位模型证实，沉默MALAT1抑制细胞自噬，同时抑制肿瘤增殖、侵袭及转移。综上，MALAT1可作为评价胰腺导管腺癌病人预后的有效指标，MALAT1通过靶向结合HuR实现对HuR-TIA-1复合体的调控，通过对TIA-1的转录后修饰，激活细胞自噬，实现对胰腺癌细胞增殖、侵袭及转移的调控。MALAT1可作为胰腺癌治疗的有效靶点。

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