Department of Radiotherapy, The People's Hospital of Zhengzhou University (Henan Provincial People's Hospital), Zhengzhou, Henan, China (mainland).
Med Sci Monit. 2017 Oct 6;23:4798-4807. doi: 10.12659/msm.905370.
BACKGROUND LncRNA X inactive specific transcript (XIST) was reported to function as an oncogene in nasopharyngeal carcinoma cells (NPC) by sponging miR-34a-5p. However, the role of XIST in modulating the radiosensitivity of NPC cells and its mechanism still remain undefined. MATERIAL AND METHODS The expressions of XIST and miR-29c in NPC cells were evaluated by qRT-PCR. CNE1 and CNE2 cells were transfected with si-XIST, pcDNA-XIST, miR-29c mimics, anti-miR-29c, or respective controls by Lipofectamine 2000. The effects of XIST knockdown and miR-29c overexpression on cell proliferation, survival fraction, and γ-H2AX expression were investigated by CCK-8 assay, colony formation assay, immunofluorescence, and Western blot, respectively. Luciferase reporter assay and qRT-PCR analysis were performed to confirm whether XIST interacts with miR-29c and regulates its expression. RESULTS XIST was upregulated and miR-29c was downregulated in NPC cells. The expressions of XIST and miR-29c changed reversely in response to irradiation. Knockdown of XIST and miR-29c overexpression both resulted in a dramatic suppression of cell proliferation, a marked enhancement of radiosensitivity, and an obvious increase of γ-H2AX foci formation in NPC cells. Luciferase reporter assay and qRT-PCR analysis demonstrated that XIST interacts with miR-29c and negatively regulates its expression. Moreover, miR-29c inhibition abrogated XIST knockdown-induced cell proliferation inhibition and radiosensitivity increase in NPC cells. CONCLUSIONS XIST knockdown suppressed cell proliferation and enhanced radiosensitivity of NPC cells by upregulating miR-29c, providing a novel therapeutic target to improve radiotherapy efficiency for patients with NPC.
长链非编码 RNA X 失活特异性转录物（XIST）被报道通过海绵 miR-34a-5p 在鼻咽癌细胞（NPC）中发挥癌基因作用。然而，XIST 调节 NPC 细胞放射敏感性的作用及其机制仍未确定。
通过 qRT-PCR 评估 NPC 细胞中 XIST 和 miR-29c 的表达。用 Lipofectamine 2000 将 si-XIST、pcDNA-XIST、miR-29c 模拟物、anti-miR-29c 或各自的对照转染至 CNE1 和 CNE2 细胞。通过 CCK-8 测定、集落形成测定、免疫荧光和 Western blot 分别研究 XIST 敲低和 miR-29c 过表达对细胞增殖、存活分数和 γ-H2AX 表达的影响。通过荧光素酶报告基因测定和 qRT-PCR 分析证实 XIST 是否与 miR-29c 相互作用并调节其表达。
XIST 在 NPC 细胞中上调，miR-29c 下调。XIST 和 miR-29c 的表达在照射后呈相反变化。XIST 敲低和 miR-29c 过表达均导致 NPC 细胞增殖明显抑制、放射敏感性显著增强和 γ-H2AX 焦点形成明显增加。荧光素酶报告基因测定和 qRT-PCR 分析表明，XIST 与 miR-29c 相互作用并负调控其表达。此外，miR-29c 抑制消除了 XIST 敲低诱导的 NPC 细胞增殖抑制和放射敏感性增加。
XIST 敲低通过上调 miR-29c 抑制 NPC 细胞增殖并增强放射敏感性，为提高 NPC 患者放疗效率提供了新的治疗靶点。
