OBJECTIVE To determine the expression and functional roles of a long noncoding RNA (lncRNA) X-inactive specific transcript (XIST) in leiomyoma. DESIGN Experimental study. SETTING Academic research laboratory. PATIENT(S) Women undergoing hysterectomy for leiomyoma. INTERVENTION(S) Overexpression and underexpression of XIST; blockade of specific protein 1 (SP1). MAIN OUTCOME MEASURE(S) Expression of XIST in leiomyoma and its effects on microRNA 29c (miR-29c), miR-200c, and their targets. RESULT(S) Leiomyoma expressed statistically significantly more XIST as compared with matched myometrium, independent of race/ethnicity and menstrual cycle phase. By use of a three-dimensional spheroid culture system, we found reduced XIST levels in leiomyoma smooth muscle cells (LSMC) after treatment with 17β-estradiol, progesterone, and their combination. The expression of XIST was down-regulated by treatment with the SP1-inhibitor mithramycin A and SP1 small interfering RNA. Knockdown of XIST resulted in inhibition of cell proliferation, up-regulation of miR-29c and miR-200c, and a concomitant inhibition of the target genes of these miRNAs, namely collagen type I (COL1A1), collagen type III (COL3A1), and fibronectin (FN1). By contrast, overexpression of XIST in myometrium smooth muscle cells repressed miR-29c and miR-200c, and induced COL1A1, COL3A1, and FN1 levels. By use of RNA immunoprecipitation analysis we confirmed XIST has sponge activity over miR-29c and miR-200c, which is more pronounced in leiomyoma as compared with myometrium. CONCLUSION(S) Our data demonstrate that increased expression of XIST in leiomyoma results in reduced expression of miR-29c and miR-200c with a consequent up-regulation of the genes targeted by these microRNAs including COL1A1, COL3A1, and FN1, which play key roles in extracellular matrix accumulation associated with fibroids.

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长链非编码 RNA X 失活特异性转录本在平滑肌瘤发病机制中的功能作用

目的 确定长链非编码 RNA (lncRNA) X 失活特异性转录本 (XIST) 在平滑肌瘤中的表达和功能作用。设计 实验研究。设置学术研究实验室。患者 因平滑肌瘤而接受子宫切除术的女性。干预（S） XIST 的过度表达和表达不足；阻断特定蛋白 1 (SP1)。主要观察指标 XIST 在平滑肌瘤中的表达及其对 microRNA 29c (miR-29c)、miR-200c 及其靶标的影响。结果与匹配的子宫肌层相比，平滑肌瘤在统计学上显着表达更多的 XIST，与种族/民族和月经周期无关。通过使用三维球体培养系统，我们发现用 17β-雌二醇、黄体酮及其组合治疗后平滑肌瘤平滑肌细胞 (LSMC) 中的 XIST 水平降低。通过用 SP1 抑制剂光神霉素 A 和 SP1 小干扰 RNA 处理，XIST 的表达被下调。XIST 的敲低导致细胞增殖的抑制、miR-29c 和 miR-200c 的上调以及这些 miRNA 的靶基因的伴随抑制，即 I 型胶原蛋白 (COL1A1)、III 型胶原蛋白 (COL3A1) 和纤连蛋白 (FN1)。相比之下，XIST 在子宫肌层平滑肌细胞中的过表达抑制了 miR-29c 和 miR-200c，并诱导了 COL1A1、COL3A1 和 FN1 水平。通过使用 RNA 免疫沉淀分析，我们证实 XIST 对 miR-29c 和 miR-200c 具有海绵活性，与子宫肌层相比，这在平滑肌瘤中更为明显。