p53诱导的外泌体-miRNAs介导头颈肿瘤细胞化疗耐药的机制

Studies have confirmed that the sensitivity of tumor cells to chemotherapy can be regulated by tumor associated fibroblasts (CAF). However, the detailed mechanism remains unclear. Exosomes are small vesicles containing unique RNA and protein cargo, secreted by most cell types in culture. One of their most intriguing roles is intercellular communication-exosomes function as the messengers, delivering various effectors or signaling macromolecules between specific cells. Our previous results showed that : ① Tumor cells can block cisplatin -induced DNA damage when CAF co-cultured with tumor cells; ② After removal of the exosomes from CAF and tumor cells co-culture system, tumor cells restored the sensitivity to chemotherapeutic drugs; ③ After silencing of p53 gene in CAF, exosomes released by CAF significantly reduced. Based on these results, we conclude that the activation of p53 in CAF under the pressure of DNA damage caused by chemotherapy drugs can enhance exosome production. The p53-related exosomes-miRNAs may be involved in DNA repair and chemoresistance. In this study, we choose the tumor microenvironment as our study scopes, and mainly focus on the mechanism of chemoresistance mediated by the exosomes derived from CAF. This study will facilitate to provide some strategies for cancer therapy based on exosomes. In addition, exosomes also can be designed to be a drugs-delivering vector for cancer therapy.

研究证实，肿瘤相关成纤维细胞（CAF）可以调控肿瘤细胞对化疗的敏感性，但是详细机制尚不明确。外泌体是细胞分泌的一种小囊泡结构，包含多种miRNAs，可以在遗传信息层面介导不同类型细胞之间进行信息交流。我们前期实验结果表明：① CAF与肿瘤细胞共培养时，肿瘤细胞能够有效抵抗顺铂所致的DNA损伤及凋亡发生；② 去除CAF与肿瘤细胞共培养体系中的外泌体后，肿瘤细胞重新恢复了对化疗药物的敏感性；③ 将CAF的p53基因沉默后，CAF释放的外泌体显著减少。基于以上实验结果，我们推断，在化疗药物的DNA损伤压力下，p53功能活化后可调控CAF释放外泌体，而外泌体中与p53相关的miRNAs可能参与介导肿瘤细胞DNA修复及耐药的形成。本研究以CAF来源的外泌体为主要研究对象，研究其在肿瘤化疗抵抗中的作用机制。该问题的解决将为以外泌体为治疗靶点的治疗手段以及以外泌体为药物载体的治疗方式提供科学依据。

肿瘤相关成纤维细胞（CAF）在肿瘤细胞恶性进展及化疗耐药等方面具有重要作用。但是正常成纤维细胞（NF）如何转化为CAF以及CAF促进肿瘤进展的机制尚不完全清楚。我们系统研究了CAF调控肿瘤细胞生长及化疗耐药的分子机制：（A）我们原代培养鉴定了30对NF及CAF细胞；通过分子生物学方法检测NFs与CAFs的生物学表征；通过芯片方法检测了NF与CAF中差异表达的miRNAs。研究证实miR-7可促进NF向CAF转化；（B）我们检测了口腔鳞癌中骨桥蛋白（OPN）的表达水平；分析了OPN升高相关与口腔鳞癌患者不良预后的相关性；肿瘤相关成纤维细胞衍生的IL-6可以诱导肿瘤细胞中OPN表达升高，OPN进而通过自分泌的形式激活NF-kappaB信号通路，促进肿瘤细胞生长；（C）研究显示，p85S6K1可以通过HIV TAT样结构（N末端六精氨酸基序）由癌细胞直接分泌；p85S6K1可以对癌旁上皮细胞进行恶性转化，促进或赋予上皮细胞恶性行为，促进细胞生长和迁移；（D）我们通过lncRNA表达谱芯片检测了阿司匹林诱导的特征性lncRNAs 表达谱；阿司匹林通过诱导lncRNA OLA1P2表达，进而抑制磷酸化STAT3 同源二聚体形成，最终发挥抑癌功能。（D）我们采用超滤结合免疫沉淀的方法从口腔鳞癌细胞中分离获得外泌体；分子生物学方法证实了口腔癌细胞来源的外泌体可被NK细胞内化，进而促进NK细胞生物学功能的机制。以上研究证实：CAF细胞在肿瘤进展中发挥着非常的作用，将CAF细胞作为肿瘤诊治靶标的设想具有广阔的前景。.本项目共发表SCI论文6篇，分别发表在Genome Biology（通讯作者）、Theranostics（通讯作者）、Oral Oncology（通讯作者）、Cell death & Disease（通讯作者）、Science Signaling（第一作者）、oncotarget（通讯作者）。