Molecular Biomedicine Program and Biotechnology Network, Instituto Politecnico Nacional, México City 07320, Mexico.
Translational Medicine Laboratory, National Institute of Cancerology, México City 14080, Mexico.
Oncol Rep. 2018 Jun;39(6):3086-3094. doi: 10.3892/or.2018.6366. Epub 2018 Apr 12.
Altered expression of microRNAs contributes to the heterogeneous biological behavior of human malignancies and it may correlate with the clinical pathological features of patients. The let-7 microRNA family is frequently downregulated in human cancers and its aberrant expression may be a useful marker for prediction of the clinical response to therapy in patients. In the present study, we analyzed the expression of three members of the let-7 family (let-7a-3p, let-7d-3p and let-7f), which remains largely uncharacterized in ovarian cancer tissues. We also investigated the function of let-7d-3p in the apoptosis and sensitization to chemotherapy in ovarian cancer cells. Our data from stem-loop quantitative RT-PCR showed that expression of let-7a-3p and let-7d-3p, but not let-7f, was significantly (P<0.04) upregulated in ovarian tumors relative to that noted in normal ovarian tissues. Markedly, an increased expression of let‑7d-3p (also known as let-7d-3*) was associated with positive response to carboplatin/paclitaxel treatment in ovarian cancer patients. To investigate the biological relevance of let‑7d-3p, we knocked down its expression in SKOV-3 ovarian cancer cell line using antagomiRs. Loss of function analysis showed that inhibition of let-7d-3p significantly (P<0.05) impaired cell proliferation and activated apoptosis. In contrast, scratch/wound healing and Transwell chamber assays showed that migration and invasion abilities were not affected in the let-7d-3p-deficient SKOV-3 cancer cells. Notably, Annexin V assays showed a significant (P<0.05) increase in cell death of cancer cells treated with the let-7d-3p inhibitor plus carboplatin indicating a synergistic effect of the drug with antagomiR therapy. Gene ontology classification of predicted targets of let-7d-3p identified a number of genes involved in cellular pathways associated with therapy resistance such as ABC transporters, HIF-1, RAS and ErbB signaling. In summary, our findings showed that inhibition of let-7d-3 activates apoptosis and that its upregulation is associated with a positive response of ovarian cancer patients to carboplatin/paclitaxel chemotherapy.
miRNA 的表达改变导致人类恶性肿瘤的异质性生物学行为，并且可能与患者的临床病理特征相关。let-7 微 RNA 家族在人类癌症中经常下调，其异常表达可能是预测患者对治疗临床反应的有用标志物。在本研究中，我们分析了三个 let-7 家族成员（let-7a-3p、let-7d-3p 和 let-7f）的表达，这些成员在卵巢癌组织中尚未得到充分表征。我们还研究了 let-7d-3p 在卵巢癌细胞凋亡和化疗敏感性中的功能。我们的茎环定量 RT-PCR 数据显示，与正常卵巢组织相比，卵巢肿瘤中 let-7a-3p 和 let-7d-3p 的表达显著上调（P<0.04），但 let-7f 的表达没有上调。值得注意的是，卵巢癌患者中 let-7d-3p（也称为 let-7d-3*）的表达增加与顺铂/紫杉醇治疗的阳性反应相关。为了研究 let-7d-3p 的生物学相关性，我们使用 antagomiRs 敲低了 SKOV-3 卵巢癌细胞系中的表达。功能丧失分析表明，抑制 let-7d-3p 显著（P<0.05）损害细胞增殖并激活凋亡。相比之下，划痕/伤口愈合和 Transwell 室测定显示，let-7d-3p 缺陷的 SKOV-3 癌细胞的迁移和侵袭能力没有受到影响。值得注意的是，Annexin V 测定显示，用 let-7d-3p 抑制剂加卡铂处理的癌细胞死亡显著增加（P<0.05），表明药物与 antagomiR 治疗具有协同作用。let-7d-3p 预测靶标的基因本体分类确定了一些参与与治疗耐药相关的细胞途径的基因，如 ABC 转运蛋白、HIF-1、RAS 和 ErbB 信号。总之，我们的研究结果表明，抑制 let-7d-3 可激活凋亡，其上调与卵巢癌患者对顺铂/紫杉醇化疗的阳性反应相关。
