尿路上皮癌相关1基因通过竞争性抑制miR-18a增强乳腺癌细胞的他莫昔芬治疗耐药

Urothelial carcinoma-associated 1 enhances tamoxifen resistance in breast cancer cells through competitively inhibiting miR-18a

目的:探讨尿路上皮癌相关1(urothelial carcinoma-associated 1,UCA1)基因及miR-18a在雌激素受体(estrogen receptor,ER)阳性的乳腺癌细胞他莫昔芬耐药中的作用和调控机制。方法:通过反转录实时定量PCR测定乳腺癌细胞中UCA1和miR-18a的表达,用双荧光素酶报告实验验证miR-18a和UCA1 3'UTR区域结合。在他莫昔芬敏感的MCF-7细胞中过表达UCA1或敲减miR-18a,在他莫昔芬耐药的LCC9和BT474细胞中敲减UCA1或过表达miR-18a,CCK-8方法测定细胞活力,软琼脂克隆形成实验测定细胞克隆形成能力,流式细胞术测定细胞周期。结果:他莫昔芬耐药的LCC2、LCC9和BT474细胞中,UCA1表达量显著高于他莫昔芬敏感的MCF-7细胞。MCF-7细胞在0.1μmol/L他莫昔芬处理后,UCA1的表达水平显著升高。UCA1过表达提高了MCF-7细胞在他莫昔芬处理后的活力,而UCA1 siRNA则显著降低了LCC9和BT474细胞在他莫昔芬处理后的活力。在MCF-7细胞中,相对于质粒对照+他莫昔芬组,UCA1+他莫昔芬组的克隆数目多19.0%,克隆平均大小增加29.0%,G1期细胞比例减少7.3%,S期细胞增加6.7%。在BT474细胞中,相对于siRNA对照+他莫昔芬组,si-UCA1+他莫昔芬组的克隆数目少54.0%,克隆平均大小减少42.0%,G1期细胞比例增加9.0%,S期细胞减少6.2%。UCA1有一个miR-18a结合位点,敲减miR-18a提高了MCF-7细胞在他莫昔芬处理后的活力,过表达miR-18a则显著降低了BT474细胞在他莫昔芬处理后的活力。在MCF-7细胞中,相对于对照+他莫昔芬组,miR-18a抑制+他莫昔芬组的克隆数目多15.0%,克隆平均大小增加33.0%,G1期细胞比例减少8.8%,S期细胞增加5.3%。在BT474细胞中,相对于对照+他莫昔芬组,miR-18a过表达+他莫昔芬组的克隆数目少47.0%,克隆平均大小减少25.0%,G1期细胞比例增加13.3%,S期细胞减少7.9%。结论:UCA1可以通过竞争性抑制miR-18a增强乳腺癌细胞的他莫昔芬治疗耐药。

Objective：To investigate how urothelial carcinoma-associated 1 （UCA1） and miR-18a modulates acquired tamoxifen resistance and the relevant mechanisms in estrogen receptor （ER） positive cancer cells.Methods： qRT-PCR was performed to detect UCA1 and miR-18a expression in breast cancer cells.Dual luciferase assay was performed to detect the binding between miR-18a and UCA1 3′UTR.Tamoxifen sensitive MCF-7 cells were transfected with UCA1 expression vector or miR-18a inhi-bitors.Tamoxifen resistant LCC9 and BT474 cells were transfected with UCA1 siRNA or miR-18a mi-mics.CCK-8 assay was performed to detect cell viability.Soft agar assay was performed to assess cell colony formation.Flow cytometric analysis was performed to check cell cycle distribution.Results： UCA1 was significantly upregulated in tamoxifen resistant LCC2,LCC9,and BT474 cells than in tamoxifen sensitive MCF-7 cells.UCA1 expression was significantly upregulated in MCF-7 cells after treatment with 0.1 μmol/L tamoxifen.UCA1 overexpression enhanced cell viability of MCF-7 cells after tamoxifen treatment,while UCA1 siRNA significantly suppressed viability of LCC9 and BT474 cells after tamoxifen treatment.In MCF-7 cells,compared with vector control＋tamoxifen group,the average cell colony number and colony size of the UCA1＋tamoxifen group was 19.0% more and 29.0% larger respectively,while the proportions of the cells in G1 phase and in S phase were 7.3% lower and 6.7% higher respectively.In BT474 cells,compared with siRNA control＋tamoxifen group,the average cell colony number and colony size of the si-UCA1＋tamoxifen group were 54.0% less and 42.0% smaller respectively,while the proportions of the cells in G1 phase and in S phase were 9.0% higher and 6.2% lower respectively.UCA1 directly interacted with miR-18a and reduced its expression in ER positive breast cancer cells.Knockdown of miR-18a increased viability of MCF-7 cells after tamoxifen treatment,while miR-18a overexpression significantly reduced viability of BT474 cells after tamoxifen treatment.In MCF-7 cells,compared with miRNA inhibitor control＋tamoxifen group,the average cell colony number and colony size of the miR-18a inhibitor＋tamoxifen group were 15.0% more and 33.0% larger respectively,while the proportions of the cells in G1 phase and in S phase were 8.8% lower and 5.3% higher respectively.In BT474 cells,compared with miRNA control＋tamoxifen group,the average cell colony number and colony size of the miR-18a mimics＋tamoxifen group were 47.0% less and 25.0% smaller respectively,while the proportions of the cells in G1 phase and in S phase were 13.3% higher and 7.9% lower respectively.Conclusion： UCA1 can increase tamoxifen resistance of ER positive breast cancer cells via competitively inhibiting of miR-18a.