Li Xiu Juan, Ren Zhao Jun, Tang Jin Hai, Yu Qiao
The First Clinical School of Nanjing Medical University, Nanjing, China.
Department of General Surgery, Jiangsu Cancer Hospital, Jiangsu Institute of Cancer Research, Nanjing Medical University Affiliated Cancer Hospital, Nanjing, China.
Cell Physiol Biochem. 2017;44(5):1741-1748. doi: 10.1159/000485780. Epub 2017 Dec 6.
BACKGROUND/AIMS: Treatment of breast cancer remains a clinical challenge. This study aims to validate exosomal microRNA-1246 (miR-1246) as a serum biomarker for breast cancer and understand the underlying mechanism in breast cancer progression.
The expression levels of endogenous and exosomal miRNAs were examined by real time PCR, and the expression level of the target protein was detected by western blot. Scanning electron and confocal microscopy were used to characterize exosomes and to study their uptake and transfer. Luciferase reporter plasmids and its mutant were used to confirm direct targeting. Furthermore, the functional significance of exosomal miR-1246 was estimated by invasion assay and cell viability assay.
In this study, we demonstrate that exosomes carrying microRNA can be transferred among different cell lines through direct uptake. miR-1246 is highly expressed in metastatic breast cancer MDA-MB-231 cells compared to non-metastatic breast cancer cells or non-malignant breast cells. Moreover, miR-1246 can suppress the expression level of its target gene, Cyclin-G2 (CCNG2), indicating its functional significance. Finally, treatment with exosomes derived from MDA-MB-231 cells could enhance the viability, migration and chemotherapy resistance of non-malignant HMLE cells.
Together, our results support an important role of exosomes and exosomal miRNAs in regulating breast tumor progression, which highlights their potential for applications in miRNA-based therapeutics.
背景/目的：乳腺癌的治疗仍然是一项临床挑战。本研究旨在验证外泌体微小RNA-1246（miR-1246）作为乳腺癌的血清生物标志物，并了解其在乳腺癌进展中的潜在机制。
通过实时PCR检测内源性和外泌体miRNA的表达水平，通过蛋白质印迹法检测靶蛋白的表达水平。使用扫描电子显微镜和共聚焦显微镜对外泌体进行表征，并研究其摄取和转移。使用荧光素酶报告质粒及其突变体来确认直接靶向。此外，通过侵袭试验和细胞活力试验评估外泌体miR-1246的功能意义。
在本研究中，我们证明携带微小RNA的外泌体可以通过直接摄取在不同细胞系之间转移。与非转移性乳腺癌细胞或非恶性乳腺细胞相比，miR - 124在转移性乳腺癌MDA - MB - -细胞中高表达。此外，miR -可以抑制其靶基因细胞周期蛋白-G2（CCNG2）的表达水平，表明其功能意义。最后用MDA - MB -细胞来源的外泌体处理可增强非恶性HMLE细胞活力、迁移能力和化疗耐药性。
总之，我们的结果支持外泌体和外泌体miRNA在调节乳腺肿瘤进展中起重要作用，这突出了它们在基于miRNA的治疗中的应用潜力。
