Yang Jie, Zhang Yixuan, Gao Xin, Yuan Yue, Zhao Jing, Zhou Siqi, Wang Hui, Wang Lei, Xu Guifang, Li Xihan, Wang Pin, Zou Xiaoping, Zhu Dongming, Lv Ying, Zhang Shu
Department of Gastroenterology, Nanjing University Medical School Affiliated Nanjing Drum Tower Hospital, Nanjing, China.
Department of General Surgery and Pancreatic Disease Research Center, The First Affiliated Hospital of Soochow University, Suzhou, China.
Front Oncol. 2021 May 5;11:628346. doi: 10.3389/fonc.2021.628346. eCollection 2021.
Pancreatic cancer (PC) has a dismal prognosis due to its insidious early symptoms and poor early detection rate. Exosomes can be released by various cell types and tend to be a potential novel biomarker for PC detection. In this study, we explored the proteomic profiles of plasma exosomes collected from patients with PC at different stages and other pancreatic diseases.
Plasma samples were collected from six groups of patients, including PC at stage I/II, PC at stage III/IV, well-differentiated pancreatic neuroendocrine tumor (P-NET), pancreatic cystic lesions (PCLs), chronic pancreatitis (CP), and healthy controls (HCs). Plasma-derived exosomes were isolated by ultracentrifugation and identified routinely. Isobaric tags for relative and absolute quantification (iTRAQ) based proteomic analysis along with bioinformatic analysis were performed to elucidate the biological functions of proteins. The expression of exosomal ALIX was further confirmed by enzyme-linked immunosorbent assay in a larger cohort of patients. Furthermore, receiver operating characteristic curve analysis was applied to evaluate the potential of ALIX as a novel diagnostic biomarker.
The proteomic profile revealed a total of 623 proteins expressed among the six groups, and 16 proteins with differential degrees of abundance were found in PC other pancreatic diseases (including P-NET, PCLs, and CP). Based on the results of proteomic and bioinformatic analyses, exosomal ALIX was subsequently selected as a novel biomarker for PC detection and validated in another clinical cohort. We noticed that ALIX expression was elevated in PC patients compared with patients with other pancreatic diseases or HC, and it was also closely associated with TNM stage and distant metastasis. Interestingly, the combination of exosomal ALIX and serum CA199 has greater values in differentiating both early late PC (AUC value 0.872) and PC other pancreatic diseases (AUC value 0.910) than either ALIX or CA199 alone.
In summary, our study demonstrated that based on proteomic profiling, proteins isolated from the plasma-derived exosomes may function as ideal non-invasive biomarkers for the clinical diagnosis of PC. Importantly, exosomal ALIX combined with CA199 has great potentials in detection of PC, especially in distinguishing PC patients at early stages from advanced stages.
胰腺癌（PC）因其隐匿的早期症状和较低的早期检测率，预后较差。外泌体可由多种细胞类型释放，有望成为检测胰腺癌的新型潜在生物标志物。在本研究中，我们探索了不同阶段胰腺癌患者以及其他胰腺疾病患者血浆外泌体的蛋白质组学特征。
收集了六组患者的血浆样本，包括I/II期胰腺癌患者、III/IV期胰腺癌患者、高分化胰腺神经内分泌肿瘤（P-NET）患者、胰腺囊性病变（PCL）患者、慢性胰腺炎（CP）患者和健康对照者（HC）。通过超速离心法分离血浆来源的外泌体并进行常规鉴定。采用基于相对和绝对定量同位素标记（iTRAQ）的蛋白质组学分析及生物信息学分析来阐明蛋白质的生物学功能。通过酶联免疫吸附测定法在更大规模的患者队列中进一步验证外泌体ALIX的表达。此外，应用受试者工作特征曲线分析来评估ALIX作为新型诊断生物标志物的潜力。
蛋白质组学分析显示，六组样本中共表达了623种蛋白质，在胰腺癌与其他胰腺疾病（包括P-NET、PCL和CP）之间发现了16种丰度差异程度不同的蛋白质。基于蛋白质组学和生物信息学分析结果，随后选择外泌体ALIX作为检测胰腺癌的新型生物标志物，并在另一个临床队列中进行了验证。我们注意到，与其他胰腺疾病患者或健康对照者相比，胰腺癌患者的ALIX表达升高，并且它还与TNM分期和远处转移密切相关。有趣的是，外泌体ALIX与血清CA199联合使用在区分早期和晚期胰腺癌（AUC值为0.872）以及胰腺癌与其他胰腺疾病（AUC值为0.910）方面比单独使用ALIX或CA199具有更高的价值。
总之，我们的研究表明，基于蛋白质组学分析，从血浆来源的外泌体中分离出的蛋白质可能作为胰腺癌临床诊断的理想非侵入性生物标志物。重要的是，外泌体ALIX与CA199联合使用在检测胰腺癌方面具有很大潜力，特别是在区分早期和晚期胰腺癌患者方面。
