De novo sequencing of circulating miRNAs identifies novel markers predicting clinical outcome of locally advanced breast cancer.

MicroRNAs (miRNAs) have been recently detected in the circulation of cancer patients, where they are associated with clinical parameters. Discovery profiling of circulating small RNAs has not been reported in breast cancer (BC), and was carried out in this study to identify blood-based small RNA markers of BC clinical outcome. The pre-treatment sera of 42 stage II-III locally advanced and inflammatory BC patients who received neoadjuvant chemotherapy (NCT) followed by surgical tumor resection were analyzed for marker identification by deep sequencing all circulating small RNAs. An independent validation cohort of 26 stage II-III BC patients was used to assess the power of identified miRNA markers. More than 800 miRNA species were detected in the circulation, and observed patterns showed association with histopathological profiles of BC. Groups of circulating miRNAs differentially associated with ER/PR/HER2 status and inflammatory BC were identified. The relative levels of selected miRNAs measured by PCR showed consistency with their abundance determined by deep sequencing. Two circulating miRNAs, miR-375 and miR-122, exhibited strong correlations with clinical outcomes, including NCT response and relapse with metastatic disease. In the validation cohort, higher levels of circulating miR-122 specifically predicted metastatic recurrence in stage II-III BC patients. Our study indicates that certain miRNAs can serve as potential blood-based biomarkers for NCT response, and that miR-122 prevalence in the circulation predicts BC metastasis in early-stage patients. These results may allow optimized chemotherapy treatments and preventive anti-metastasis interventions in future clinical applications.

微小RNA（miRNAs）近期在癌症患者的血液循环中被检测到，且与临床参数相关。在乳腺癌（BC）中，循环小RNA的发现性分析尚未见报道，本研究旨在确定基于血液的乳腺癌临床预后的小RNA标志物。 对42例接受新辅助化疗（NCT）后进行肿瘤手术切除的II - III期局部晚期和炎性乳腺癌患者的治疗前血清进行了分析，通过对所有循环小RNA进行深度测序来确定标志物。使用一个由26例II - III期乳腺癌患者组成的独立验证队列来评估所确定的miRNA标志物的效力。 在血液循环中检测到800多种miRNA，观察到的模式显示与乳腺癌的组织病理学特征相关。确定了与雌激素受体（ER）/孕激素受体（PR）/人表皮生长因子受体2（HER2）状态以及炎性乳腺癌有差异相关性的循环miRNA组。通过聚合酶链反应（PCR）测定的选定miRNAs的相对水平与其通过深度测序确定的丰度一致。两种循环miRNAs，miR - 375和miR - 122，与临床预后（包括NCT反应以及伴有转移性疾病的复发）表现出强相关性。在验证队列中，循环miR - 122水平较高特异性地预测了II - III期乳腺癌患者的转移性复发。 我们的研究表明，某些miRNAs可作为新辅助化疗反应的潜在基于血液的生物标志物，并且循环中miR - 122的存在可预测早期乳腺癌患者的转移。这些结果可能在未来的临床应用中优化化疗治疗和预防性抗转移干预措施。