Liu Kaisheng, Ma Rong
Department of Breast Surgery, Qilu Hospital of Shandong University, Jinan, Shandong 250012, P.R. China.
Exp Ther Med. 2021 Mar;21(3):192. doi: 10.3892/etm.2021.9624. Epub 2021 Jan 7.
Breast cancer, which commonly occurs in the epithelium of the mammary gland, is a malignant tumor. MicroRNAs are involved in various cancer-associated processes, and microRNA-615-5p has been identified to be decreased in the pathological tissues from patients with breast cancer. In the present study, the possible mechanism of microRNA-615-5p in the progression of breast cancer was investigated in order to identify potential novel targets for clinical treatment. Heat shock factor 1 (HSF1) was identified as a predictive target gene of microRNA-615-5p using TargetScan analysis. The expression levels of microRNA-615-5p and its target gene, HSF1, were measured in breast cancer tissues and normal adjacent tissues. Additionally, the effects of microRNA-615-5p on MCF-7 breast cancer cell growth and apoptosis were examined. Furthermore, the interaction between HSF1 and microRNA-615-5p was investigated by a dual luciferase gene reporter assay. The expression levels of HSF1 were measured following transfection with microRNA-615-5p or pcDNA3.1-HSF1. Finally, the expression levels of proliferation- and apoptosis-associated factors such as B-cell lymphoma 2 (Bcl-2), cyclin D1, proliferating cell nuclear antigen (PCNA) and bcl-2-like protein 4 (Bax) were determined. The results demonstrated that lower microRNA-615-5p expression and higher HSF1 mRNA expression were present in tumor tissues compared with adjacent tissues (P<0.01). HSF1 was verified as a direct target of microRNA-615-5p using the dual luciferase gene reporter assay. In comparison with untransfected control and mimic-transfected negative control (NC) cells, MCF-7 cells transfected with microRNA-615-5p mimics exhibited reduced cell proliferation and increased apoptosis (P<0.01). However, the overexpression of HSF1 using a vector reversed the suppression of HSF1 induced by microRNA-615-5p mimics (P<0.01). The mRNA and protein expression levels of Bax were significantly increased, whereas those of Bcl-2, cyclin D1 and PCNA were decreased in the cells transfected with microRNA-615-5p mimics compared with the control and NC cells (P<0.01). Collectively, the present study indicated that microRNA-615-5p may mediate the progression of breast cancer by targeting HSF1.
乳腺癌是一种恶性肿瘤，常见于乳腺上皮。微小RNA参与多种癌症相关过程，且已发现在乳腺癌患者的病理组织中微小RNA - 615 - 5p水平降低。在本研究中，为了确定潜在的临床治疗新靶点，对微小RNA - 615 - 5p在乳腺癌进展中的可能机制进行了研究。使用TargetScan分析确定热休克因子1（HSF1）为微小RNA - 615 - 5p的预测靶基因。检测了乳腺癌组织和癌旁正常组织中微小RNA - 615 - 5p及其靶基因HSF1的表达水平。此外，研究了微小RNA - 615 - 5p对MCF - 7乳腺癌细胞生长和凋亡的影响。进一步通过双荧光素酶基因报告分析研究了HSF1与微小RNA - 615 - 5p之间的相互作用。在用微小RNA - 615 - 5p或pcDNA3.1 - HSF1转染后，检测了HSF1的表达水平。最后，测定了增殖和凋亡相关因子如B细胞淋巴瘤2（Bcl - 2）、细胞周期蛋白D1、增殖细胞核抗原（PCNA）和bcl - 2样蛋白4（Bax）的表达水平。结果表明，与癌旁组织相比，肿瘤组织中微小RNA - 615 - 5p表达较低，HSF1 mRNA表达较高（P<0.01）。使用双荧光素酶基因报告分析验证HSF1是微小RNA - 615 - 5p的直接靶标。与未转染的对照细胞和模拟物转染的阴性对照（NC）细胞相比，用微小RNA - 615 - 5p模拟物转染的MCF - 7细胞增殖减少，凋亡增加（P<0.01）。然而，使用载体过表达HSF1可逆转微小RNA - 615 - 5p模拟物诱导的HSF1抑制（P<0.01）。与对照细胞和NC细胞相比，用微小RNA - 615 - 5p模拟物转染的细胞中Bax的mRNA和蛋白表达水平显著升高，而Bcl - 2、细胞周期蛋白D1和PCNA的表达水平降低（P<0.01）。总体而言，本研究表明微小RNA - 615 - 5p可能通过靶向HSF1介导乳腺癌的进展。
