Department of Oncology, The First Affiliated Hospital of Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510405, P.R. China.
Department of Chronic Disease Epidemiology, Yale School of Public Health, School of Medicine, Yale University, New Haven, CT 06520, USA.
Oncol Rep. 2020 Jun;43(6):2062-2072. doi: 10.3892/or.2020.7549. Epub 2020 Mar 18.
Breast cancer is the most common cancer type and the leading cause of cancer‑associated mortality in women across the majority of countries. In general, the incidence of breast cancer has been decreasing in developed countries over the previous 20 years, while it has increased in the other areas, such as the Asian‑Pacific region. MicroRNA‑34a (miR‑34a) targets stem cell‑associated transcription factors E2F1/E2F3, and may have clinical relevance in breast cancer. The present study aimed to investigate the association between miR‑34a/E2F1/E2F3 and patient survival in breast cancer, as well as the underlying molecular mechanism of miR‑34a in suppressing factors associated with tumor aggressiveness in vitro. Kaplan‑Meier survival curves were constructed and a meta‑analysis was performed to analyze the association of miR‑34a, E2F1 and E2F3 expression and overall survival in breast cancer, and the differential expression levels of E2F1 and E2F3 between breast cancer and normal breast tissues was assessed using publicly accessed datasets. Then 2D and 3D experiments on cell cultures were performed in vitro on both T‑47D and MDA‑MB‑231 cells to investigate the cancer biology of miR‑34a and its effect on E2F1 and E2F3 expression using reverse transcription‑quantitative PCR. Then, caspase‑3 (CASP3) activity was measured using a CaspACE™ assay system. E2F1 and E2F3 expression levels were upregulated in breast cancer, compared with normal breast tissues. Both high miR‑34a, and low E2F1 and E2F3 mRNA levels were positively associated with longer survival times in patients with breast cancer. The in vitro 2D and 3D cell experiments revealed that overexpression of miR‑34a significantly downregulated the expression of E2F1 and E2F3, and increased CASP3 activity in both T‑47D and MDA‑MB‑231 cells, and that miR‑34a treatment inhibited tumor cell proliferation, migration and invasiveness, as well as 3D spheroid formation. Thus, miR‑34a influences the aggressiveness of breast cancer and patient survival, and is a potential therapeutic tool in the clinical management of breast cancer.
乳腺癌是大多数国家最常见的癌症类型，也是导致女性癌症相关死亡的主要原因。一般来说，在过去的 20 年中，发达国家的乳腺癌发病率一直在下降，而在亚洲-太平洋地区等其他地区则有所上升。微小 RNA-34a (miR-34a) 靶向干细胞相关转录因子 E2F1/E2F3，并且在乳腺癌中可能具有临床相关性。本研究旨在探讨 miR-34a/E2F1/E2F3 与乳腺癌患者生存之间的关系，以及 miR-34a 在体外抑制与肿瘤侵袭性相关因子的潜在分子机制。构建 Kaplan-Meier 生存曲线，并进行荟萃分析，以分析 miR-34a、E2F1 和 E2F3 表达与乳腺癌总生存率的相关性，以及通过公共访问数据集评估 E2F1 和 E2F3 在乳腺癌与正常乳腺组织之间的差异表达水平。然后，在 T-47D 和 MDA-MB-231 细胞的体外进行二维和三维细胞培养实验，以研究 miR-34a 的癌症生物学及其对 E2F1 和 E2F3 表达的影响，方法是使用逆转录-定量 PCR。然后，使用 CaspACE™测定系统测量 caspase-3 (CASP3) 活性。与正常乳腺组织相比，乳腺癌中 E2F1 和 E2F3 的表达水平上调。miR-34a 高表达和 E2F1 和 E2F3 mRNA 水平低与乳腺癌患者的生存时间延长呈正相关。体外 2D 和 3D 细胞实验表明，miR-34a 的过表达显著下调了 T-47D 和 MDA-MB-231 细胞中 E2F1 和 E2F3 的表达，并增加了 CASP3 活性，miR-34a 处理抑制了肿瘤细胞的增殖、迁移和侵袭，以及 3D 球体的形成。因此，miR-34a 影响乳腺癌的侵袭性和患者的生存，并且是乳腺癌临床管理中的一种潜在治疗工具。
