Department of Otorhinolaryngology, Tianjin Medical University General Hospital, Tianjin, China (mainland).
Department of Emergency Medicine, Tianjin Medical University General Hospital, Tianjin, China (mainland).
Med Sci Monit. 2019 Apr 29;25:3161-3169. doi: 10.12659/MSM.915624.
BACKGROUND Radio-resistance is an obstacle to the treatment of human nasopharyngeal carcinoma (NPC). However, how microRNAs (miRNA) are involved in this process remains unclear. In the present study we explored the role and possible molecular mechanism of miR-29a-3p, formerly known as tumor suppressors, in radio-sensitivity of NPC cells. MATERIAL AND METHODS A radio-resistant sub-cell line, CNE-2R, was established to detect the expression of miR-29a/b/c-3p using qRT-PCR. CCK-8 assay, colony formation assay, and single-cell gel electrophoresis (SCGE) assay were carried out to analyze the radio-sensitivity of NPC cells. qRT-PCR, luciferase reporter, and Western blot experiments were performed to validate the targeting of COL1A1 by miR-29a. Short interference RNAs (siRNAs) were used to investigate whether COL1A1 mediates the radio-sensitizer role of miR-29a. Expression of miR-29a and COL1A1 in radio-resistant NPC tissues was finally determined. RESULTS miR-29a was decreased in the radio-resistant CNE-2R cells. Following a time-course irradiation (IR) exposure, miR-29a exhibited a time-dependent decrease. Cellular experiments confirmed that miR-29a induced radio-sensitivity of CNE-2R cells via suppressing cell viability and enhancing cell apoptosis after IR. We confirmed that COL1A1 is a direct target of miR-29a and can exert radio-resistance effects in NPC cells. We also found that knockdown of COL1A1 inhibits NPC cell viability and sensitivity to IR. Finally, we observed a downregulation of miR-29a in radio-resistant NPC tissues and its decrease was associated with upregulation of COL1A1. CONCLUSIONS miR-29a is a critical determinant of NPC radio-response for NPC patients, and its induction provides a promising therapeutic choice to elevate NPC radio-sensitivity.
放射抵抗是人类鼻咽癌（NPC）治疗的障碍。然而，miRNA（miRNA）如何参与这一过程尚不清楚。在本研究中，我们探讨了 miR-29a-3p（以前称为肿瘤抑制剂）在 NPC 细胞放射敏感性中的作用和可能的分子机制。
建立放射抗性亚细胞系 CNE-2R，使用 qRT-PCR 检测 miR-29a/b/c-3p 的表达。CCK-8 测定、集落形成测定和单细胞凝胶电泳（SCGE）测定分析 NPC 细胞的放射敏感性。qRT-PCR、荧光素酶报告和 Western blot 实验验证 miR-29a 对 COL1A1 的靶向作用。使用短发夹 RNA（siRNA）研究 COL1A1 是否介导 miR-29a 的放射增敏作用。最后确定放射抗性 NPC 组织中 miR-29a 和 COL1A1 的表达。
miR-29a 在放射抗性 CNE-2R 细胞中减少。随着时间进程照射（IR）暴露，miR-29a 呈时间依赖性减少。细胞实验证实，miR-29a 通过抑制细胞活力和增强 IR 后细胞凋亡，诱导 CNE-2R 细胞的放射敏感性。我们证实 COL1A1 是 miR-29a 的直接靶标，并能在 NPC 细胞中发挥放射抵抗作用。我们还发现，COL1A1 的敲低抑制 NPC 细胞活力和对 IR 的敏感性。最后，我们观察到放射抗性 NPC 组织中 miR-29a 的下调，其降低与 COL1A1 的上调相关。
miR-29a 是 NPC 放射反应的关键决定因素，其诱导为提高 NPC 放射敏感性提供了有前途的治疗选择。
