Liu Xiaoyan, Li Yongjun, Li Zhuo, Hou Tian
Department of Breast Surgery, Affiliated Hospital of Hebei University of Engineering, Handan, Hebei 056200, P.R. China.
Department of Imaging, Affiliated Hospital of Hebei University of Engineering, Handan, Hebei 056200, P.R. China.
Exp Ther Med. 2021 Mar;21(3):218. doi: 10.3892/etm.2021.9650. Epub 2021 Jan 15.
Breast cancer (BC) is the second leading cause of cancer-associated deaths among women worldwide. Increasing evidence has indicated that microRNAs (miRNAs) have demonstrated great potential for improving the diagnosis and therapy for BC. In the present study, miRNA-155 was detected in human BC tissues using reverse transcription-quantitative (RT-q)PCR. RT-qPCR and western blot assays were used to analyze the levels of transforming growth factor β receptor type II (TGFBR2) in human BC tissues. MCF-7 cells were cultured and treated with miR-155 inhibitor and an MTT assay was performed to determine the role of miR-155 on the proliferation of MCF-7 cells. Subsequently, TGFBR2 and epithelial-mesenchymal transition (EMT)-associated molecules were analyzed using RT-qPCR and western blot assays. The direct binding of miR-155 to TGFBR2 was validated using a dual luciferase assay. Higher levels of miR-155 and lower levels of TGFBR2 were expressed in human BC tissues compared with paired normal tissues. Furthermore, the expression levels of miR-155 were associated with the tumor size, TNM stage and metastasis status of BC. Transfection of MCF-7 cells with miR-155 inhibitors resulted in reduced cell proliferation and suppressed the EMT process, characterized by upregulated expression of the epithelial markers, E-cadherin and CK18, and downregulated expression of mesenchymal markers, fibronectin and smooth muscle actin α. Transfection of a miR-155 inhibitor also resulted in increased expression of TGFBR2, and miR-155 may have regulated TGFBR2 through direct binding to the 3'untranslated region of TGFBR2 as determined using a dual-luciferase assay. Based on the results of the present study, miR-155 may serve as a novel diagnostic biomarker and therapeutic target for patients with BC.
乳腺癌（BC）是全球女性癌症相关死亡的第二大主要原因。越来越多的证据表明，微小RNA（miRNA）在改善BC的诊断和治疗方面已显示出巨大潜力。在本研究中，使用逆转录定量（RT-q）PCR检测人BC组织中的miRNA-155。采用RT-qPCR和蛋白质免疫印迹法分析人BC组织中转化生长因子β受体II型（TGFBR2）的水平。培养MCF-7细胞并用miR-155抑制剂处理，进行MTT试验以确定miR-155对MCF-7细胞增殖的作用。随后，采用RT-qPCR和蛋白质免疫印迹法分析TGFBR2和上皮-间质转化（EMT）相关分子。使用双荧光素酶试验验证miR-155与TGFBR2的直接结合。与配对的正常组织相比，人BC组织中miR-155水平较高，TGFBR2水平较低。此外，miR-155的表达水平与BC的肿瘤大小、TNM分期和转移状态相关。用miR-155抑制剂转染MCF-7细胞导致细胞增殖减少，并抑制EMT过程，其特征是上皮标志物E-钙黏蛋白和细胞角蛋白18的表达上调，间质标志物纤连蛋白和平滑肌肌动蛋白α的表达下调。转染miR-155抑制剂还导致TGFBR2表达增加，并且如双荧光素酶试验所确定的，miR-155可能通过直接结合TGFBR2的3'非翻译区来调节TGFBR2。基于本研究结果，miR-155可能作为BC患者的一种新型诊断生物标志物和治疗靶点。
