长链非编码RNA BDNF-AS在乳腺癌中的表达及作用

  目的  探讨长链非编码RNA（long non-coding RNA，lncRNA）脑源性神经营养因子（brain-derived neurotrophic factor，BDNF）-AS在乳腺癌组织和细胞系中的表达及其对乳腺癌癌细胞增殖、凋亡、迁移和侵袭的影响。  方法  收集2016年1月至2018年12月88例于兰州大学第一医院行乳腺癌手术切除患者的组织样本。RT-qPCR检测癌组织、癌旁组织、乳腺癌细胞系（MCF-7、MDA-MB-231、MDA-MB-468和SK-BR-3）及正常乳腺细胞HBL-100中lncRNA BDNF-AS的表达并分析其与临床特征的相关性。MDA-MB-231细胞经pcDNA3.1质粒过表达lncRNA BDNF-AS，使用MTT法检测细胞活性，EdU实验检测细胞增殖能力，比色法检测Caspase-3活性；Western blot检测凋亡相关蛋白（Bax、Bcl-2）、侵袭转移相关蛋白（MMP-9、E-cadherin）和BDNF蛋白表达，划痕实验和Transwell实验检测细胞迁移和侵袭。  结果  lncRNA BDNF-AS在乳腺癌组织（P < 0.05）和乳腺癌细胞中表达显著降低（P < 0.01）。乳腺癌组织中的lncRNA BDNF-AS表达与患者TNM分期（P < 0.05）和淋巴结转移（P < 0.05）呈负相关。lncRNABDNF-AS过表达可降低MDA-MB-231细胞活性（P < 0.01）、EdU检测的阳性细胞数（P < 0.01）、Caspase-3活性（P < 0.01），下调Bcl-2蛋白和上调Bax蛋白表达（P < 0.01）。lncRNA BDNF-AS过表达可抑制划痕愈合和细胞侵袭（P < 0.01），下调MMP-9蛋白和上调Ecadherin蛋白表达（P < 0.01）及下调BDNF mRNA和蛋白的表达。  结论  在乳腺癌中lncRNA BDNF-AS表达下调，BDNF-AS抑制乳腺癌细胞增殖、迁移和侵袭，并促进凋亡。 

Expression and function of lncRNA BDNF-AS in breast cancer

  Objective  To determine expression of brain-derived neurotrophic factor antisense (BDNF-AS) long non-coding RNA (lncRNA) in breast cancer, and to investigate its effects on proliferation, apoptosis, migration and invasion.  Methods  Between 2016 and 2018, samples from 88 cases of breast cancer were collected at the First Hospital of Lanzhou University. RT-qPCR was used to determine expression of lncRNA BDNF-AS in breast cancer tissue and cells. A pcDNA3.1 plasmid was used to overexpress BDNF-AS in MDAMB-231 cells. Cell viability was quantified using an MTT assay, proliferative capacity was determined using an EdU assay and a colorimetric assay was used to measure the Caspase-3 activity. Moreover, the protein levels of Bax, Bcl-2, MMP-9, E-cadherin, and BDNF were quantified by Western blot. Scratch and transwell assays were used to determine cell migration and invasion.  Results  Lower lncRNA BDNF-AS expression was observed in breast cancer tissue and cells compared with normal paracancerous tissues (P < 0.05), and with normal, HBL-100 breast cells (P < 0.01). BDNF-AS expression negatively correlated with tumor-node-metastasis (TNM) stage (P < 0.05) and lymphatic metastasis (P < 0.05) of breast cancer. Overexpression of BDNF-AS with the pcDNA3.1 plasmid decreased viability of MDA-MB-231 cells (P < 0.01), EdU-positive cells (P < 0.01), and Caspase-3 activity (P < 0.01). Additionally, Bcl-2, MMP-9, and BDNF expression was downregulated (P < 0.01), while Bax and E-cadherin expression was upregulated (P < 0.01). Overexpression of BDNF-AS also inhibited cell healing and invasion which were determined by scratch assays (P < 0.01).  Conclusions  LncRNA BDNF-AS expression is downregulated in breast cancer, which inhibits breast cancer cell proliferation, migration, invasion, and promotes apoptosis.