Department of Breast Surgery, Chifeng Municipal Hospital, Chifeng, China.
Department of Breast and Thyroid Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Neoplasma. 2019 Jun 3;66(5):746-755. doi: 10.4149/neo_2018_181207N930. Print 2019 Sep.
MiR-21-5p has been identified as an oncogene to enhance human tumor progression. Here, we explored the mechanism by which miR-21-5p regulated the progression and paclitaxel (PTX) resistance in drug-resistant breast cancer (BC) cell lines. qRT-PCR assays were used to assess the expression levels of miR-21-5p and PDCD4 mRNA, and western blotting was used to detect PDCD4 protein level in PTX-resistant BC cell lines. Dual-luciferase reporter assay was used to observe the interaction between miR-21-5p and PDCD4 in PTX-resistant BC cell lines. Cell proliferation ability and IC50 values of PTX were measured by CCK-8 assay, cell cycle progression and apoptosis were determined with flow cytometry analysis, and cell migration and invasion capacities were analyzed using Transwell assay. Xenograft mice assay was used to validate the important role of miR-21-5p as a regulator on PTX-resistance BC cells growth in vivo. Then, we found that miR-21-5p was upregulated and PDCD4 was downregulated in BC tissues and PTX-resistant BC cell lines. MiR-21-5p silencing or PDCD4 overexpression ameliorated PTX resistance and inhibited the progression in PTX-resistant BC cell lines. Moreover, PDCD4 was demonstrated to be a direct target of miR-21-5p. MiR-21-5p exerted its regulatory effect by PDCD4 in PTX-resistant BC cell lines. Additionally, miR-21-5p silencing inhibited tumor growth in vivo. Therefore, our study demonstrated that miR-21-5p silencing ameliorated PTX resistance and inhibited the progression in PTX-resistant BC cell lines at least partly by targeting PDCD4, providing miR-21-5p as an effective therapeutic target for PTX-resistant BC treatment.
miR-21-5p 已被鉴定为一种癌基因，可增强人类肿瘤的进展。在这里，我们探讨了 miR-21-5p 调节耐药乳腺癌（BC）细胞系进展和紫杉醇（PTX）耐药的机制。qRT-PCR 检测用于评估 miR-21-5p 和 PDCD4 mRNA 的表达水平，Western blot 用于检测 PTX 耐药 BC 细胞系中 PDCD4 蛋白水平。双荧光素酶报告基因检测用于观察 miR-21-5p 和 PDCD4 在 PTX 耐药 BC 细胞系中的相互作用。CCK-8 法测定细胞增殖能力和 PTX 的 IC50 值，流式细胞术分析细胞周期进程和细胞凋亡，Transwell 法分析细胞迁移和侵袭能力。异种移植小鼠实验用于验证 miR-21-5p 作为调节子在体内对 PTX 耐药 BC 细胞生长的重要作用。然后，我们发现 miR-21-5p 在 BC 组织和 PTX 耐药 BC 细胞系中上调，PDCD4 下调。miR-21-5p 沉默或 PDCD4 过表达可改善 PTX 耐药并抑制 PTX 耐药 BC 细胞系的进展。此外，PDCD4 被证明是 miR-21-5p 的直接靶标。miR-21-5p 通过 PDCD4 在 PTX 耐药 BC 细胞系中发挥其调节作用。此外，miR-21-5p 沉默抑制体内肿瘤生长。因此，我们的研究表明，miR-21-5p 沉默通过靶向 PDCD4 改善 PTX 耐药并抑制 PTX 耐药 BC 细胞系的进展，为 PTX 耐药 BC 的治疗提供了 miR-21-5p 作为有效的治疗靶点。
