Long noncoding RNA MEG3 suppresses cell proliferation, migration and invasion, induces apoptosis and paclitaxel-resistance via miR-4513/PBLD axis in breast cancer cells

Breast cancer remains a general-threat event in the health of women. Currently, increasing records indicate that long non-coding RNA maternally expressed 3 (MEG3) plays a central role in breast cancer. The current research focused on the function of MEG3 in paclitaxel (PTX)-resistance and human breast cancer growth. Levels of MEG3, microRNA (miR)-4513, and phenazine biosynthesis-like domain-containing protein (PBLD) were evaluated using quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assays. 3-(4.5-dimethylghiazol-2-yl)-2,5-diphenyltetrazolium Bromide (MTT) assay was performed to examine the IC50 of PTX and cell proliferation in breast cancer cells. In addition, cell apoptosis was determined utilizing flow cytometry. Transwell was conducted to assay cell migration and invasion in MCF-7 and MDA-MB-231 cells. The interaction between miR-4513 and MEG3 or PBLD was expounded via dual-luciferase reporter assay. Levels of MEG3 and PBLD were decreased, but miR-4513 level was triggered in breast cancer tissues and cell lines. Overexpression of MEG3 could reinforce cell apoptosis, impede proliferation, migration, invasion, and the IC50 of PTX in breast cancer cells. Moreover, the impact of miR-4513 inhibitor on cell progression and PTX-resistance was overturned by MEG3 deficiency. Interestingly, miR-4513 mimic could abolish the role of PBLD upregulation in cell behaviors and PTX-resistance in MCF-7 and MDA-MB-231 cells. Finally, the expression of PBLD was co-modulated by miR-4513 and MEG3 in vitro. MEG3/miR-4513/PBLD axis modulated PTX-resistance and the development of breast cancer cells, which might provide a promising therapeutic strategy for breast cancer.

乳腺癌仍是威胁女性健康的普遍健康问题。当前越来越多的研究表明，长链非编码RNA母系表达基因3（long non-coding RNA maternally expressed 3，MEG3）在乳腺癌中发挥核心调控作用。本研究聚焦于MEG3在紫杉醇（paclitaxel，PTX）耐药及人乳腺癌细胞增殖中的功能。
采用实时荧光定量聚合酶链反应（quantitative real-time polymerase chain reaction，qRT-PCR）或蛋白质印迹（western blot）实验检测MEG3、微小RNA（microRNA，miR）-4513及含吩嗪生物合成样结构域蛋白（phenazine biosynthesis-like domain-containing protein，PBLD）的表达水平。采用3-(4,5-二甲基噻唑-2)-2,5-二苯基四氮唑溴盐（3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium Bromide，MTT）实验检测乳腺癌细胞的紫杉醇半数抑制浓度（IC50）与细胞增殖能力。此外，通过流式细胞术检测细胞凋亡水平。利用Transwell实验检测MCF-7及MDA-MB-231细胞的迁移与侵袭能力。采用双荧光素酶报告基因实验阐明miR-4513与MEG3或PBLD之间的相互调控关系。
在乳腺癌组织及细胞系中，MEG3与PBLD的表达水平均下调，而miR-4513的表达水平则显著上调。过表达MEG3可增强乳腺癌细胞凋亡，抑制其增殖、迁移及侵袭能力，并降低乳腺癌细胞对紫杉醇的半数抑制浓度。此外，MEG3缺失可逆转miR-4513抑制剂对细胞进程及紫杉醇耐药性的调控作用。有趣的是，miR-4513模拟物可抵消PBLD过表达对MCF-7及MDA-MB-231细胞行为及紫杉醇耐药性的影响。最后，体外实验证实，miR-4513与MEG3共同调控PBLD的表达。
MEG3/miR-4513/PBLD调控轴可调节乳腺癌细胞的紫杉醇耐药性及增殖发展，这可为乳腺癌的临床治疗提供潜在的新策略。