Abstract: ［Abstract］ Objective To study the function and mechanism of estrogen receptor?regulated long non?coding RNA RP11-321G12.1 in breast cancer. Methods In the previous study，estrogen receptor-regulated long non?coding RNAs were screened by bioinformatics analysis. In this study，after silencing RP11?321G12.1 by siRNA in ER positive breast cancer cell lines MCF7 and T47D，the effect of RP11? 321G12.1 on cell proliferation and cell cycle was investigated using plate colony formation assay and flow cytometry. The molecular mechanisms involved in RP11?321G12.1 in breast cancer were studied by q?PCR and western blot. Results Silencing of RP11?321G12.1 inhibited the proliferation of MCF7（P= 0.003）and T47D（P=0.001）；it also inhibited the cell cycle，showing as an increase in the ratio of G1 phase cells and a decrease in the ratio of S? phase cells. In the Hu-blocked release assay in T47D cell line，it was found that RP11-321G12.1 was positively correlated with the cell cycle G1 phase （P= 0.039）. Western blot experiments showed that silencing of RP11-321G12.1 can result a decrease inpositive breast cancer. When the ER-regulated lncRNA RP11-321G12.1 is silenced，the cell cycle progression can be inhibited by down-regulating the protein expression levels of the cell cycle-related proteins Cyclin D1 and Cyclin E2，so that the ratio of G1 phase cells is increased and the ratio of S phase cells is decreased. Cell proliferation was significantly inhibited.

Key words: long non?coding RNA, cell cycle, breast cancer, RP11?321G12.1

摘要： ［摘要］ 目的 研究乳腺癌中雌激素受体调控的长链非编码 RNA（lncRNAs）RP11?321G12.1 在乳腺癌中的功能及机制。方法 前期研究发现RP11?321G12.1 是雌激素受体（ER）调控的长链非编码 RNA。本研究中，在 ER 阳性的乳腺癌细胞系 MCF7 和T47D 中，siRNA 沉默 RP11?321G12.1 后，利用平板克隆形成实验和流式细胞术研究RP11?321G12.1 对细胞增殖和细胞周期的影响。通过q?PCR 和western blot 实验研究RP11?321G12.1 在乳腺癌中可能参与的分子机制。结果 平板克隆实验显示敲低RP11?321G12.1 可以抑制显著MCF7 的增殖（P=0.003）和T47D 的增殖（P=0.001）； 且可以抑制细胞周期，表现为G1 期细胞比值增高和DNA 合成的S 期细胞比值降低。T47D 细胞系的周期阻滞释放实验，发现RP11?321G12.1 与细胞周期的G1 期成正相关（P=0.039）。western blot 实验表明下调RP11?321G12.1 可以使G1 期相关的周期蛋白Cyclin D1 和Cyclin E2 在蛋白水平下降。结论 RP11-321G12.1 在 ER 阳性的乳腺癌组织中高表达。当沉默 ER 调控的 lncRNAs RP11 ?321G12.1，可以通过下调细胞周期相关蛋白Cyclin D1 和Cyclin E2 的蛋白表达水平，抑制细胞周期进程，使G1 期细胞比值增高，S 期细胞比值降低，表现为细胞增殖被显著抑制。

关键词: RP11?321G12.1, 乳腺癌, 细胞周期, 长链非编码RNA