miR-155-JARID2介导丙戊酸对神经胶质瘤替莫唑胺的化疗增敏作用及机制研究

Temozolomide (TMZ) is a first-line agent for chemotherapy against glioma, and TMZ chemoresistance is the main cause of recurrence and death of glioma. It is important to elucidate the underlying mechanisms of TMZ chemoresistance to improve the treatment efficacy of glioma. In our previous work, we have found that the expression of JARID2 in IDH1 mutant tumor tissues was up-regulated , the expression of miR-155 was down-regulated and miR-155 negatively regulated the expression of JARID2. Meanwhile, valproic acid (VPA) was found to enhance the chemosensitivity of TMZ and increase the expression of JARID2. Based on these findings, we will firstly verify the effects of the expression of miR-155 and JARID2 on TMZ chemosensitivity and prognosis of glioma. Secondly,we will make clear that IDH1 mutations promote miR-155 methylation,up-regulate the expression of JARID2, therefore strengthen TMZ chemosensitivity and its molecular mechanism by pyrosequencing and chromatin immunoprecipitation assay. Finally,we will confirm that VPA influences the expression of JARID2 and its target genes, and increases TMZ chemosensitivity by regulating the expression of miR-155 in vivo and in vitro. This study will provide new insight for individualized therapy for gliomas and provide potentially new targets for the treatment of gliomas.

替莫唑胺（TMZ）是治疗胶质瘤的一线化疗药物，TMZ化疗抵抗是胶质瘤复发和死亡的主要原因，阐明TMZ化疗抵抗机制对提高胶质瘤的疗效有重要意义。本项目前期发现IDH1突变肿瘤组织中JARID2表达上调，miR-155表达下调，且miR-155负调控JARID2的表达；同时发现丙戊酸（VPA）可增加胶质瘤细胞株对TMZ的敏感性，同时上调JARID2表达的基础上，拟通过临床研究和细胞实验查明miR-155、JARID2的表达对胶质瘤患者TMZ敏感性和预后的影响；应用焦磷酸测序法、染色质免疫共沉淀等技术明确IDH1突变通过促进miR-155甲基化，上调JARID2的表达增强TMZ敏感性及其分子机制；最后通过体内外实验证明VPA通过调节miR-155的表达而影响JARID2及其靶基因的表达，从而增加TMZ敏感性，为寻找胶质瘤治疗的新靶点和基于新靶点的个体化治疗奠定坚实的理论基础。

替莫唑胺（TMZ）是目前治疗胶质瘤的一线化疗药物，TMZ化疗抵抗是影响胶质瘤疗效的主要原因，探究TMZ增敏机制对提高胶质瘤的疗效有重要意义。课题组前期研究发现IDH1突变胶质瘤组织中JARID2表达上调，miR-155表达下调，且miR-155负调控JARID2的表达；同时发现丙戊酸（VPA）可增加胶质瘤细胞株对TMZ的敏感性，并上调JARID2的表达。CCND1是细胞周期G1/S期转化的关键调控因子，参与细胞增殖和分化的启动和调控。本项目通过免疫组化及qPCR检测发现随着胶质瘤级别升高，JARID2的表达下调，而CCND1的表达上调，两者呈负相关。通过在线工具预测并证实了JARID2和CCND1启动子区域之间存在结合位点，并且发现JARID2通过靶向CCND1并抑制其表达，从而调控胶质瘤细胞生长增殖及其对TMZ的化疗敏感性。同时，通过双荧光素酶报告基因实验进一步明确了miR-155靶向JARID2并负调控其表达，影响胶质瘤细胞生长增殖。初步阐明了VPA/miR-155/JARID2轴增强胶质瘤TMZ化疗敏感性的机制，即VPA通过促进miR-155启动子甲基化，下调miR-155表达，进而上调JARID2的表达，从而增强胶质瘤对TMZ化疗的敏感性。本项目研究结果为探明胶质瘤TMZ化疗增敏机制，寻找胶质瘤治疗的新靶点奠定了理论基础，并为基于新靶点的胶质瘤个体化治疗提供了新的思路。