肿瘤特异性外泌体在肿瘤发生发展中起重要作用。其脂质双层膜的保护作用使其内容物长链非编码RNA（lncRNA）在作为肿瘤标志物方面独具优势。申请人从肺癌患者血清中分离出肿瘤标志物EpCAM特异性外泌体，并经体外和体内实验证明其促进肺癌进展。我们进一步从EpCAM特异性外泌体中筛选出与肺癌生长相关的lncRNA RP11-77G23.5和PHEX-AS1。由于逆转录-微滴数字PCR（RT-ddPCR）具有灵敏度、精确度高等优点，特别适用于绝对定量血液中RNA类标志物。为此，本项目将优化引物浓度和扩增片段长度，实现RT-ddPCR同时定量检测RP11-77G23.5和PHEX-AS1；检验EpCAM特异性外泌体中lncRNA的稳定性；分析健康人、肺炎、良性肺肿瘤和肺癌4组人血清EpCAM特异性外泌体中RP11-77G23.5和PHEX-AS1拷贝数及其与临床资料的相关性，确定其对肺癌的诊断价值。

Tumor-specific exosomes play important roles in the occurrence and development of tumors. The protective effect of their lipid bilayer membranes makes their content long non-coding RNAs (lncRNAs) have unique advantages as tumor markers. The applicant isolated tumor marker, epithelial cell adhesion molecule (EpCAM)-specific exosomes from the serum of patients with lung cancer, and demonstrated that they promoted lung cancer progression in vitro and in vivo. We further screened out two lung cancer growth-associated lncRNAs RP11-77G23.5 and PHEX-AS1. Since reverse transcription-droplet digital polymerase chain reaction (RT-ddPCR) has the advantages of high sensitivity and accuracy, it is especially suitable for the absolute quantification of RNA-typed markers in blood. Accordingly, in this project, we will optimize the primers’ concentrations and the size of amplified fragments to achieve the simultaneous quantification of RP11-77G23.5 and PHEX-AS1 by RT-ddPCR, and test the stabilities of lncRNAs in EpCAM-specific exosomes, and analyze the copy number changes of RP11-77G23.5 and PHEX-AS1 within serum EpCAM-specific exosomes among healthy controls, patients with pneumonia, benign and malignant lung tumors, as well as their correlations with clinical parameters, and finally determine their value in the diagnosis of lung cancer.