miR-24靶向调控Sp1对鼻咽癌放射敏感性的影响

The morbidity of nasopharyngeal carcinoma in Guangxi is highest in China. Currently radiotherapy is the major treatment for this tumor, while radiation resistance leading to its local treatment failure and distant metastases. Our previous research found that the miR-24 expression was down-regulated in the tissues of nasopharyngeal carcinoma and its low expression was associated with bad prognosis after radiotherapy. Based on these data we raise the hypothesis in this study: miR-24 involved in the regulation of radiosensitivity of nasopharyngeal carcinoma cells, and exogenous increased miR-24 may improve the effect of radiotherapy for this tumor. To validate this speculation, we will first analyze the miR-24 expression levels in nasopharyngeal cancer tissues, and their association with nasopharyngeal cancer pathology factors; we will then explore the effect of miR-24 highly expression on radiosensitivity of nasopharyngeal carcinoma cells on multiple levels of molecule, cell, tissue and animal experiments, using biological informatics, miRNA plasmid transfection, RT-PCR, and Western blot, based on the nasopharyngeal carcinoma cell culture and nude mosue model of implanted nasopharyngeal carcinoma; finally we will study the changes of Sp1, which is one of the miR-24 target genes, during the experiments motioned above, to probe into the regulation of miR-24 in oncogene expression. Accomplishment of this study item will explicit the role of miR-24 in regulation of radiosensitivity of nasopharyngeal carcinoma, and the molecular mechanisms involved; define the possibility of miR-24 as new evaluation index for prognosis of nasopharyngeal carcinoma, while provide a new pathway to further study the other functional molecular drugs applying in the prevention and treatment of nasopharyngeal carcinoma.

鼻咽癌是广西高发肿瘤，治疗以放疗为主；对放射线抗拒是其局部治疗失败及预后不良的主要原因。前期研究发现miR-24在鼻咽癌组织中表达下调，其低表达与放疗预后不良密切相关。据此提出假设：miR-24参与鼻咽癌放射敏感性调节，外源性上调miR-24可能增加鼻咽癌放疗效果。本研究拟在鼻咽癌组织中分析miR-24表达水平与临床病理因素间的关系；在鼻咽癌细胞系和裸鼠移植瘤模型基础上，用miRNA质粒转染、RT-PCR、Western blot等方法，从分子、细胞、组织及动物水平等多层次研究miR-24对鼻咽癌放射敏感性的影响；检测上述实验中miR-24靶基因Sp1的表达变化，探讨miR-24对促癌基因表达的调节作用。项目的完成将明确miR-24对鼻咽癌放疗敏感性的调节作用及分子机制；探讨miR-24作为鼻咽癌预后新的评估指标的可能性，为进一步研究功能性分子药物在鼻咽癌防治应用上提供新的思路。

鼻咽癌是广西高发肿瘤，治疗以放疗为主；对放射线抗拒是其局部治疗失败及预后不良的主要原因。增加肿瘤细胞对放射治疗的敏感性是提高鼻咽癌放射治疗效果的关键；近年来，从分子基因组学的角度寻找高效的新型功能性分子（例如功能性microRNAs）增加肿瘤细胞对放疗的敏感性，已经成为国内外研究的热点问题之一。课题组通过体外细胞实验以及体内裸鼠移植瘤实验，得出以下结论：1、鼻咽癌组织和细胞中miR-24的表达明显下调，且miR-24表达下调与鼻咽癌病人的临床分期及T分期、N分期有关；2、在体外实验中证实miR-24对鼻咽癌细胞具有放射增敏作用；3、在体内实验中证实miR-24对鼻咽癌细胞裸鼠移植瘤具有放射增敏作用；4、阐明miR-24的放射增敏作用与靶向调控SP1有关，SP1 是miR-24的直接作用靶标，参与鼻咽癌细胞的增殖及放疗敏感性。项目的完成明确miR-24对鼻咽癌放疗敏感性的调节作用及分子机制；证实了miR-24作为鼻咽癌预后新的评估指标的可能性，内源性microRNA分子有更高的稳定性和更好的组织相容性，更低的毒副作用。因此，本项目的完成也将有助于进一步探讨microRNA作为新型分子药物或新靶点应用于鼻咽癌的临床治疗。