新辅助放化疗（nCRT）是局部晚期直肠癌（LARC）的关键治疗方法，但缺乏可靠的生物标志物来预测其疗效仍然是一个挑战。因此，本研究旨在评估小细胞外囊泡 (sEV) 的蛋白质组组成是否可以为 LARC 患者的 nCRT 反应提供预测性见解，同时还深入研究 nCRT 后 sEV 内的蛋白质组变化。血浆样本取自 LARC 患者nCRT 之前和之后。利用基于 TIO2 的方法分离血浆来源的 sEV，然后进行基于 LC-MS/MS 的蛋白质组分析。随后，对差异表达蛋白（DEP）进行通路富集分析。此外，还生成了 ROC 曲线来评估 sEV 蛋白在确定 nCRT 反应中的预测潜力。研究人员对公共数据库进行了调查，以确定与 LARC 中 nCRT 反应相关的 sEV 蛋白相关基因。总共招募了 16 名患者。其中，8例患者达到病理完全缓解（良好反应者，GR），其余8例未达到完全缓解（不良反应者，PR）。我们对预处理血浆来源的 sEV 的分析显示，67 个 DEP 显着上调，9 个 DEP 显着下调。值得注意的是，PROC（AUC：0.922）、F7（AUC：0.953）和AZU1（AUC：0.906）在区分GR和PR患者方面表现出较高的AUC值和显着差异（P值 < 0.05）。此外，由 5 个 sEV 蛋白相关基因（S100A6、ENO1、MIF、PRDX6 和 MYL6）组成的特征能够预测对 nCRT 的反应，AUC 为 0.621（95% CI：0.454-0.788）。此外，这种 5-sEV 蛋白相关基因特征可以将患者分为低风险组和高风险组，低风险组在测试组中表现出更长的总生存期（P = 0.048）。此外，我们的研究在比较 nCRT 前后的蛋白质组谱时发现了 11 个显着上调的 DEP 和 31 个显着下调的 DEP。 GO 分析揭示了磷脂酶 A2 活性调节的富集。sEV 蛋白的差异表达可区分 GR 和 PR 患者，并有望作为 LARC 患者 nCRT 反应和预后的预测标志物。此外，我们的研究结果强调了 nCRT 后 sEV 蛋白质组成的显着变化。© 2024。Springer Nature Switzerland AG。

Neoadjuvant chemoradiotherapy (nCRT) stands as a pivotal therapeutic approach for locally advanced rectal cancer (LARC), yet the absence of a reliable biomarker to forecast its efficacy remains a challenge. Thus, this study aimed to assess whether the proteomic compositions of small extracellular vesicles (sEVs) might offer predictive insights into nCRT response among patients with LARC, while also delving into the proteomic alterations within sEVs post nCRT.Plasma samples were obtained from LARC patients both pre- and post-nCRT. Plasma-derived sEVs were isolated utilizing the TIO2-based method, followed by LC-MS/MS-based proteomic analysis. Subsequently, pathway enrichment analysis was performed to the Differentially Expressed Proteins (DEPs). Additionally, ROC curves were generated to evaluate the predictive potential of sEV proteins in determining nCRT response. Public databases were interrogated to identify sEV protein-associated genes that are correlated with the response to nCRT in LARC.A total of 16 patients were enrolled. Among them, 8 patients achieved a pathological complete response (good responders, GR), while the remaining 8 did not achieve a complete response (poor responders, PR). Our analysis of pretreatment plasma-derived sEVs revealed 67 significantly up-regulated DEPs and 9 significantly down-regulated DEPs. Notably, PROC (AUC: 0.922), F7 (AUC: 0.953) and AZU1 (AUC: 0.906) demonstrated high AUC values and significant differences (P value < 0.05) in discriminating between GR and PR patients. Furthermore, a signature consisting of 5 sEV protein-associated genes (S100A6, ENO1, MIF, PRDX6 and MYL6) was capable of predicting the response to nCRT, yielding an AUC of 0.621(95% CI: 0.454-0.788). Besides, this 5-sEV protein-associated gene signature enabled stratification of patients into low- and high-risk group, with the low-risk group demonstrating a longer overall survival in the testing set (P = 0.048). Moreover, our investigation identified 11 significantly up-regulated DEPs and 31 significantly down-regulated DEPs when comparing pre- and post-nCRT proteomic profiles. GO analysis unveiled enrichment in the regulation of phospholipase A2 activity.Differential expression of sEV proteins distinguishes between GR and PR patients and holds promise as predictive markers for nCRT response and prognosis in patients with LARC. Furthermore, our findings highlight substantial alterations in sEV protein composition following nCRT.© 2024. Springer Nature Switzerland AG.