Bladder cancer (BC) diagnosis is reliant on cystoscopy, an invasive procedure associated with urinary tract infections. This has sparked interest in identifying noninvasive biomarkers in body fluids such as blood and urine. A source of biomarkers in these biofluids are extracellular vesicles (EVs), nanosized vesicles that contain a wide array of molecular cargo, including small noncoding RNA such as transfer RNA-derived fragments (tRF) and microRNA. Here, we performed small-RNA next-generation sequencing from EVs from urine and serum, as well as from serum supernatant. RNA was extracted from 15 non-cancer patients (NCPs) with benign findings in cystoscopy and 41 patients with non-muscle invasive BC. Urine and serum were collected before transurethral resection of bladder tumors (TUR-b) and at routine post-surgery check-ups. We compared levels of tRFs in pre-surgery samples to samples from NCPs and post-surgery check-ups. To further verify our findings, samples from 10 patients with stage T1 disease were resequenced. When comparing tRF expression in urine EVs between T1 stage BC patients and NCPs, 14 differentially expressed tRFs (DEtRFs) were identified. In serum supernatant, six DEtRFs were identified among stage T1 patients when comparing pre-surgery to post-surgery samples and four DEtRFs were found when comparing pre-surgery samples to NCPs. By performing a blast search, we found that sequences of DEtRFs aligned with genomic sequences pertaining to processes relevant to cancer development, such as enhancers, regulatory elements and CpG islands. Our findings display a number of tRFs that may hold potential as biomarkers for the diagnosis and recurrence-free survival of BC.
膀胱癌的诊断依赖于膀胱镜检查，这种侵入性操作与尿路感染风险相关。这促使研究者关注在血液和尿液等体液中寻找无创生物标志物。细胞外囊泡是这些生物流体中生物标志物的重要来源，这类纳米级囊泡携带包括转移RNA衍生片段和小分子RNA在内的多种非编码RNA分子。本研究对尿液、血清来源的细胞外囊泡及血清上清液进行了小RNA二代测序，样本来源于15例膀胱镜检查良性的非癌患者和41例非肌层浸润性膀胱癌患者。所有样本均在经尿道膀胱肿瘤切除术术前及术后常规复查时采集。我们将术前样本中的tRF表达水平与非癌患者及术后复查样本进行对比分析。为验证研究结果，我们对10例T1期患者的样本进行了重复测序。通过比较T1期膀胱癌患者与非癌患者的尿液细胞外囊泡，鉴定出14个差异表达的tRF；在血清上清液中，T1期患者术前与术后样本比较发现6个差异tRF，术前样本与非癌患者比较发现4个差异tRF。通过序列比对分析，我们发现差异tRF的序列与癌症发展相关的基因组区域（如增强子、调控元件和CpG岛）存在同源性。本研究鉴定出的tRF分子群可能成为膀胱癌诊断和无复发生存评估的潜在生物标志物。
肿瘤(癌症)患者之家