吉林大学学报(医学版)  2020, Vol. 46 Issue (05): 1016-1022     DOI: 10.13481/j.1671-587x.20200519

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魏旭静, 李林, 张红真, 王景, 徐静
WEI Xujing, LI Lin, ZHANG Hongzhen, WANG Jing, XU Jing
LncRNA CCAT1通过TGF-β/Smad信号通路对子宫内膜癌细胞增殖、侵袭和迁移的影响
Effects of LncRNA CCAT1 on proliferation, invasion and migration of endometrial cancer cells through TGF-β1/smad signaling pathway
吉林大学学报(医学版), 2020, 46(05): 1016-1022
Journal of Jilin University (Medicine Edition), 2020, 46(05): 1016-1022
10.13481/j.1671-587x.20200519

文章历史

收稿日期: 2019-09-23
LncRNA CCAT1通过TGF-β/Smad信号通路对子宫内膜癌细胞增殖、侵袭和迁移的影响
魏旭静 , 李林 , 张红真 , 王景 , 徐静     
河北医科大学第一医院产科, 河北 石家庄 050000
[摘要]: 目的: 探讨长链非编码核糖核酸(LncRNA)CCAT1对子宫内膜癌细胞增殖、侵袭和迁移及转化生长因子β(TGF-β)/Smad信号通路的影响,阐明LncRNA CCAT1在子宫内膜癌发生发展中的作用及可能机制。方法: 将人子宫内膜癌Ishiwaka细胞分为空白对照组、阴性对照组、CCAT1-siRNA组和CCAT1-siRNA+LY364947组,阴性对照组细胞转染阴性对照siRNA,CCAT1-siRNA组转染CCAT1-siRNA,CCAT1-siRNA+LY364947组细胞转染CCAT1-siRNA同时加入TGF-β/Smad抑制剂LY364947(3 μL),空白对照组细胞不转染。采用RT-PCR法检测各组细胞中CCAT1 mRNA表达水平,CCK8法检测各组细胞增殖能力,Transwell小室实验检测细胞侵袭和迁移能力,Western blotting法检测各组Ishiwaka细胞中增殖细胞核抗原(PCNA)、E-钙黏蛋白(E-cadherin)、波形蛋白(vimentin)、锌指转录因子(snail)、凋亡抑制蛋白(Twist)、白细胞抑制因子2/3(Smad2/3)、磷酸化Smad(p-Smad2/3)和转化生长因子β1(TGF-β1)蛋白表达水平。结果: Ishiwaka细胞中CCAT1 mRNA表达水平明显高于人子宫内膜基质T-HESC细胞(t=12.929,P < 0.01);与空白对照组和阴性对照组比较,CCAT1-siRNA组和CCAT1-siRNA+LY364947组Ishiwaka细胞中CCAT1 mRNA表达水平、细胞增殖能力、侵袭细胞数和迁移细胞数均明显降低(P < 0.05),PCNA、vimentin、snail、Twist、p-Smad2/3和TGF-β1蛋白表达水平均明显降低(P < 0.05),E-cadherin蛋白表达水平明显升高(P < 0.05);与CCAT1-siRNA组比较,CCAT1-siRNA+LY364947组Ishiwaka细胞增殖能力、侵袭细胞数和迁移细胞数均明显降低(P < 0.05),PCNA、vimentin、snail、Twist、p-Smad2/3和TGF-β1蛋白表达水平降低(P < 0.05),E-cadherin蛋白表达水平明显升高(P < 0.05);空白对照组与阴性对照组Ishiwaka细胞中各指标比较差异无统计学意义(P>0.05)。结论: 沉默LncRNA CCAT1可通过抑制TGF-β/Smad信号通路抑制子宫内膜癌细胞增殖、侵袭和迁移。
关键词: 长链非编码RNA    子宫内膜癌    细胞增殖    细胞侵袭    细胞迁移    上皮间质转化    转化生长因子-β/Smad信号通路    
Effects of LncRNA CCAT1 on proliferation, invasion and migration of endometrial cancer cells through TGF-β1/smad signaling pathway
WEI Xujing , LI Lin , ZHANG Hongzhen , WANG Jing , XU Jing     
Department of Obstetrics, First Hospital, Hebei Medical University, Shijiazhuang 050000, China
[ABSTRACT]: Objective: To investigate the effects of long-chain non-coding RNA (LncRNA) CCAT1 on the proliferation, invasion, migration and transforming growth factor-β (TGF-β)/Smad signaling pathway of the endometrial cancer cells, and to elucidate the role of CCAT1 in the occurrence and development of endometrial cancer and its possible mechanism. Methods: The human endometrial cancer Ishiwaka cells were divided into blank control group, negative control group, CCAT1-siRNA group and CCAT1-siRNA+LY364947 group.The cells in negative control group were transfected with negative control siRNA, the cells in CCAT1-siRNA group were transfected with CCAT1-siRNA; the cells in CCAT1-siRNA+LY364947 group were transfected with CCAT1-siRNA and added with LY364947 (3μL), and the cells in blank control group were not transfected.RT-PCR method was used to determine the CCAT1 miRNA expression levels.CCK8 method was used to measure proliferation abilities of cells.Transwell chamber experiment was used to measure the abilities of invasion and migration of cells.Western blotting method was used to measure the expression levels of proliferating cell nuclear antigen (PCNA), E-cadherin, vimentin, snail, Twist, Smad2/3, phosphorylated Smad2/3 (p-Smad2/3) and TGF-β1 proteins in the Ishiwaka cells in various groups. Results: The expression level of CCAT1 mRNA in the Ishiwaka cells was very obvious higher than that in the human endometrial matrix T-HESC cells (t=12.929, P < 0.01).Compared with blank control group and negative control group, the CCAT1 miRNA expression levels, the proliferation abilities of cells the number of invasion cells and the number migration cells in CCAT1-siRNA group and CCAT1-siRNA+LY36494 group were obviously decreased (P < 0.05), the expression levels of PCNA, vimentin, snail, Twist, p-Smad2/3 and TGF-β1 proteins were obviously decreased (P < 0.05), and the expression levels of E-cadherin protein were obviously increased (P < 0.05). Compared with CCAT1-siRNA group, the proliferation ability of cells, the number of invasion cells and the number of migration cells in CCAT1-siRNA+LY364947 group were obviously decreased (P < 0.05), the expression levels of PCNA, vimentin, snail, Twist, p-Smad2/3 and TGF-β1 proteins were obviously decreased (P < 0.05), and the expression level of E-cadherin protein was obviously increased (P < 0.05).There were no significant differences in the indexes mentioned above in the Ishiwaka cells between blank control group and negative control group (P>0.05). Conclusion: Silencing LncRNA CCAT1 can inhibit the proliferation, invasion and migration of endometrial cancer cells by inhibiting the TGF-β/Smad signaling pathway.
KEYWORDS: long non-coding RNA    endometrial cancer    cell proliferation    cell invasion    cell migration    epithelial-mesenchymal transition    transforming growth factor-β/Smad signaling pathway    

子宫内膜癌是女性常见的恶性肿瘤,其发病机制复杂,探讨其发生发展机制对其诊治及改善其预后具有重要价值。近年来,子宫内膜癌细胞增殖、侵袭迁移及其分子机制方面的研究取得了巨大进步,长链非编码核糖核酸(long non coding RNA,LncRNA)在胚胎发育、基因表达和肿瘤发生等过程中发挥重要作用,多种LncRNA参与子宫内膜癌的发生发展过程[1]。近年来研究[2]发现:LncRNA CCAT1在多种恶性肿瘤的增殖和侵袭迁移过程中发挥重要作用,在子宫内膜癌中的作用也受到研究者关注,YU等[3]研究发现:LncRNA CCAT1可促进子宫内膜癌细胞的增殖和迁移。但其通过何种信号通路在子宫内膜癌发生发展中发挥作用尚不清楚。转化生长因子β(transforming growth factor-β,TGF-β)/Smad信号通路参与子宫内膜癌的增殖及侵袭迁移过程,SAHOO等[4]研究显示:抑制细胞外基质介导的TGF-β信号转导可抑制子宫内膜癌的转移。本实验通过观察沉默CCAT1对子宫内膜癌细胞增殖、侵袭和迁移及TGF-β/Smad信号通路的影响,探讨其在子宫内膜癌中的可能作用机制。

1 材料与方法 1.1 细胞、主要试剂和仪器

人子宫内膜癌Ishiwaka细胞株和正常人子宫内膜基质细胞T-HESC(中国科学院上海细胞库);Lipofectamine 2000试剂盒(美国Invitrogen公司),CCAT1模拟物siRNA(CCAT1-siRNA)和阴性对照模拟物siRNA(广州博锐生物科技公司),ECL化学发光试剂盒、逆转录(RT)试剂盒、Trizol试剂、聚合酶链反应(PCR)试剂盒、LY364947(TGF-β/ Smad抑制剂)和结晶紫(美国Sigma公司),CCK8试剂、胰蛋白酶和DMEM培养基(美国BPB公司),兔抗人增殖细胞核抗原(PCNA)、E-钙黏蛋白(E-cadherin)、波形蛋白(vimentin)、锌指转录因子(snail)、凋亡抑制蛋白(Twist)、白细胞抑制因子2/3(Smad2/3)、磷酸化Smad 2/3(p-Smad2/3)、转化生长因子β1(TGF-β1)和兔抗人TGF-β1单克隆抗体(美国Santa Cruz公司);MultiskanTM FC酶标仪、Applied Biosystems PCR仪和NERLTM流式细胞仪(美国赛默飞世尔科技公司),Transwell小室(美国TaKaRa公司)等。

1.2 细胞培养

Ishiwaka细胞和T-HESC细胞置于DMEM(含双抗和10%胎牛血清)培养,细胞贴壁后每2 d换液1次,细胞生长至达80%以上融合时进行细胞传代培养。

1.3 实时荧光定量PCR(RT-PCR)法检测Ishiwaka细胞和T-HESC细胞中CCAT1 mRNA表达水平

取Ishiwaka和T-HESC细胞,加入Trizol裂解液裂解细胞,提取细胞总RNA,将RNA逆转录为cDNA,PCR法检测细胞中CCAT1 mRNA表达水平;CCAT1上游引物:5'-CCATTCCATTCAT-TTCTCTTTCCTA-3',下游引物:5'-GGCGTA-GGCGATTGGGGATCG-3'。PCR反应条件:95℃、30 s;95℃、5 s,58℃、30 s,72℃、30 s,共42个循环。以U6为内参照。每组设7个复孔。以2-∆∆Ct法计算细胞中CCAT1 mRNA表达水平。

1.4 细胞分组和转染

取对数生长期的Ishiwaka细胞分为空白对照组、阴性对照组、CCAT1-siRNA组和CCAT1-siRNA+LY364947组,将各组对数生长期的Ishiwaka细胞接种到6孔细胞培养板中,每孔2×105个细胞,培养至细胞达90%以上融合时进行转染,阴性对照组转染阴性对照siRNA,CCAT1-siRNA组转染CCAT1-siRNA,CCAT1-siRNA + LY364947组转染CCAT1-siRNA同时加入LY364947(3 µL)[5],空白对照组不转染。转染步骤严格参照Lipofectamine 2000试剂盒说明书进行。转染24 h后采用RT-PCR法检测细胞中CCAT1 mRNA表达水平,方法同“1.2”。

1.5 CCK8法检测Ishiwaka细胞增殖能力

取各组生长良好的Ishiwaka细胞接种到96孔细胞培养板中,每孔5×103个细胞,培养24、48和72 h时每孔分别加入10 µL的CCK8试剂,继续培养2 h,每组设7个复孔。酶标仪检测450 nm波长处各孔吸光度(A)值,以A值表示细胞增殖能力。

1.6 Transwell小室实验检测各组侵袭细胞数和迁移细胞数

取各组生长状态良好的Ishiwaka细胞用双无培养基悬浮,将含血清的正常培养基加入24孔细胞培养板中,将24孔细胞培养板放入Transwell小室,调整各组细胞个数,使200 µL培养液中含5×104个细胞,将各组细胞放入Transwell小室培养24 h,然后取出小室,甲醇固定30 min,棉签擦去内室细胞,用结晶紫染色30 min,纤维镜下观察迁移细胞数。侵袭实验在实验前用基质胶包被小室,其余步骤同迁移实验。

1.7 Western blotting法检测Ishiwaka细胞中PCNA、E-cadherin、vimentin、snail、Twist、Smad2/3、p-Smad2/3和TGF-β1蛋白表达水平

取各组转染24 h细胞加入蛋白裂解液提取细胞总蛋白,BCA法检测细胞蛋白浓度。取100 µg蛋白电泳,经转膜、5%脱脂奶粉封闭,加入一抗:兔抗人PCNA、E-cadherin、vimentin、snail、Twist、Smad2/3、p-Smad2/3和TGF-β1单克隆抗体,稀释比例1:200,过夜孵育。加入二抗(1:5 000)孵育2 h,以β-actin为内参,化学发光法显色,每组设7个复孔,凝胶电泳成像仪采集图像,Quantity One软件分析条带灰度值。目标蛋白表达水平=目标蛋白条带灰度值/β-actin条带灰度值。

1.8 统计学分析

采用SPSS 20.0统计软件进行统计学分析。不同细胞中CCAT1 mRNA表达水平、各组细胞增殖能力、迁移细胞数、侵袭细胞数以及细胞中PCNA、E-cadherin、vimentin、snail、Twist、Smad2/3、p-Smad2/3和TGF-β1蛋白表达水平经检验均符合正态分布,以x±s表示,多组间样本均数比较采用单因素方差分析,组间两两比较采用LSD-t检验。以P < 0.05为差异有统计学意义。

2 结果 2.1 不同细胞中CCAT1mRNA表达水平

Ishiwaka细胞中CCAT1 mRNA表达水平(1.94±0.17)明显高于T-HESC细胞(1.00±0.09)(t =12.929,P < 0.01)。

2.2 各组Ishiwaka细胞中CCAT1 mRNA表达水平

与空白对照组(1.00±0.08)和阴性对照组(0.99±0.10)比较,CCAT1-siRNA组和CCAT1-siRNA + LY364947组Ishiwaka细胞中CCAT1 mRNA表达水平(0.52±0.06和0.49±0.07)明显降低(P < 0.01),空白对照组与阴性对照组及CCAT1-siRNA组与CCAT1-siRNA + LY364947组Ishiwaka细胞中CCAT1表达水平比较差异无统计学意义(P>0.05)。

2.3 各组Ishiwaka细胞增殖能力

培养24 h,各组Ishiwaka细胞增殖能力比较差异均无统计学意义(P>0.05);培养48和72 h,与空白对照组和阴性对照组比较,CCAT1-siRNA组和CCAT1-siRNA+ LY364947组Ishiwaka细胞增殖能力明显降低(P < 0.05),与CCAT1-siRNA组比较,CCAT1-siRNA+LY364947组Ishiwaka细胞增殖能力明显降低(P < 0.05),空白对照组与阴性对照组Ishiwaka细胞比较差异无统计学意义(P>0.05)。见表 1

表 1 各组Ishiwaka细胞增殖能力 Tab. 1 Proliferation rates of Ishiwaka cells in various groups 
(n=7, x±s)
Group A value
(t/h) 24 48 72
Blank control 0.28±0.07 0.55±0.08 0.86±0.12
Negative control 0.27±0.09 0.57±0.09 0.85±0.13
CCAT1-siRNA 0.23±0.06 0.42±0.06*△ 0.60±0.10*△
CCAT1-siRNA+LY364947 0.22±0.05 0.31±0.05*△# 0.46±0.08*△#
F 1.271 20.06 22.595
P 0.31 < 0.01 < 0.01
      *P < 0.05 compared with blank control group; P < 0.05 compared with negative control group; # P < 0.05 compared with CCAT1-siRNA group.
2.4 各组Ishiwaka细胞中侵袭细胞数和迁移细胞数

与空白对照组和阴性对照组比较,CCAT1-siRNA组和CCAT1-siRNA + LY364947组Ishiwaka细胞中侵袭细胞数和迁移细胞数明显降低(P < 0.05);与CCAT1-siRNA组比较,CCAT1-siRNA + LY364947组Ishiwaka细胞侵袭细胞数和迁移细胞数明显降低(P < 0.05),空白对照组与阴性对照组Ishiwaka细胞中侵袭细胞数和迁移细胞数比较差异无统计学意义(P>0.05)。见表 2图 1插页五)和图 2插页五)。

表 2 各组Ishiwaka细胞中侵袭细胞数和迁移细胞数 Tab. 2 Number of invasion and migration cells in Ishiwaka cells in various groups 
(n=7, x±s)
Group Number of invasion cells Number of migration cells
Blank control 50.24±4.16 46.15±3.97
Negative control 51.43±3.98 47.02±3.73
CCAT1-siRNA 36.48±3.52*△ 24.16±3.52*△
CCAT1-siRNA + LY364947 21.43±3.26*△# 18.26±3.42*△#
F 98.494 114.873
P < 0.01 < 0.01
      *P < 0.05 compared with blank control group; P < 0.05 compared with negative control group; # P < 0.05 compared with CCAT1-siRNA group.
A: Blank control group; B: Negative control group;C:CCATl-siRNA group; D:CCAT1-siRNA十LY36494 group. 图 1 Transwell 小室法测定各组 Ishiwaka 细胞侵袭能力(结晶紫,×200) Fig. 1 Invasive abilities of Ishiwaka cells in var1ous groups determined by Transwell chamber(Crystal violet, ×200)
A: Blank control group; B: Negative control group;C:CCATl-siRNA group; D:CCAT1-siRNA十LY36494 group. 图 2 Transwell 小室测定各组 Ishiwaka 细胞迁移能力 (结晶紫,×200) Fig. 2 Migration capacities of Ishiwaka cells in various groups determined by Transwell chamber (Crystal violet, ×200)
2.5 各组Ishiwaka细胞中PCNA、E-cadherin、vimentin、snail和Twist蛋白表达水平

与空白对照组和阴性对照组比较,CCAT1-siRNA组和CCAT1-siRNA + LY364947组Ishiwaka细胞中PCNA、vimentin、snail和Twist蛋白表达水平均明显降低(P < 0.05),E-cadherin蛋白表达水平明显升高(P < 0.05);与CCAT1-siRNA组比较,CCAT1-siRNA + LY364947组Ishiwaka细胞E-cadherin蛋白表达水平明显升高(P < 0.05),其他蛋白表达水平均明显降低(P < 0.05),但空白对照组与阴性对照组Ishiwaka细胞中上述蛋白表达水平比较差异均无统计学意义(P>0.05)。见表 3图 3

表 3 Expression levels of PCNA, E-cadherin, vimentin, snail and Twist proteins in Ishiwaka cells in various groups 
n=7,x±s
Group PCNA E-cadherin vimentin snail Twist
Blank control 0.83±0.17 0.18±0.07 0.58±0.11 0.85±0.12 0.51±0.08
Negative control 0.79±0.15 0.21±0.08 0.56±0.09 0.86±0.14 0.49±0.07
CCAT1-siRNA 0.26±0.05*△ 0.56±0.11*△ 0.27±0.03*△ 0.64±0.08*△ 0.33±0.05*△
CCAT1-siRNA+LY364947 0.12±0.03*△# 0.74±0.14*△# 0.18±0.02*△# 0.32±0.07*△# 0.24±0.04*△#
F 67.275 48.55 53.515 39.533 30.591
P < 0.01 < 0.01 < 0.01 < 0.01 < 0.01
      *P < 0.05 compared with blank control group; P < 0.05 compared with negative control group; # P < 0.05 compared with CCAT1-siRNA group.
Lane 1:Blank control group; Lane 2:Negative control group; Lane 3:CCAT1-siRNA group; Lane 4:CCAT1-siRNA + LY364947 group. 图 3 Western blotting法检测Ishiwaka细胞中PCNA、E-cadherin、vimentin、snail和Twist蛋白表达电泳图 Fig. 3 Expression levels of PCNA, E-cadherin, vimentin, snail and Twist proteins in Ishiwaka cells in virous groups determined with Western blotting method
2.6 各组Ishiwaka细胞中Smad2/3、p-Smad2/3和TGF-β1蛋白表达水平

与空白对照组和阴性对照组比较,CCAT1-siRNA组和CCAT1-siRNA + LY364947组Ishiwaka细胞中p-Smad2/3和TGF-β1蛋白表达水平明显降低(P < 0.05);与CCAT1-siRNA组比较,CCAT1-siRNA + LY364947组Ishiwaka细胞中p-Smad2/3和TGF-β1蛋白表达水平明显降低(P < 0.05);空白对照组与阴性对照组Ishiwaka细胞中p-Smad2/3和TGF-β1蛋白表达水平比较差异无统计学意义(P> 0.05)。见图 4表 4

Lane 1:Blank control group; Lane 2:Negative control group; Lane 3:CCAT1-siRNA group; Lane 4:CCAT1-siRNA + LY364947 group. 图 4 Electrophoregram of expressions of Smad2/3, p-Smad2/3 and TGF-β1 proteins in Ishiwaka cells in various groups determined by Western blotting method
表 4 各组Ishiwaka细胞中Smad2/3、p-Smad2/3和TGF-β1蛋白表达水平 Tab. 4 Expression levels of Smad2/3, p-Smad2/3 and TGF-β1 proteins in Ishiwaka cells in various groups 
(n=7, x±s)
Group Smad2/3 p-Smad2/3 TGF-β1
Blank control 0.82±0.13 0.71±0.12 0.64±0.12
Negative control 0.84±0.12 0.73±0.13 0.61±0.11
CCAT1-siRNA 0.85±0.14 0.37±0.05*△ 0.25±0.03*△
CCAT1-siRNA+LY364947 0.87±0.15 0.26±0.04*△# 0.18±0.02*△#
F 0.165 44.894 57.41
P 0.92 < 0.01 < 0.01
      *P < 0.05 compared with blank control group; P < 0.05 compared with negative control group; # P < 0.05 compared with CCAT1-siRNA group.
3 讨论

LncRNA是非编码RNA家族成员,长度大于200 nt,不具备蛋白质编码功能,在染色质修饰、表观遗传和转录调控等多方面发挥重要调控作用,可促进蛋白基因表达,也可抑制基因表达[6]。近年来研究[7-8]显示:多种LncRNA与恶性肿瘤的发生发展关系密切,在恶性肿瘤的发生发展中发挥抑癌或促癌作用,与靶蛋白组织的复杂的调控网络在细胞增殖、分化、凋亡和侵袭迁移中发挥重要的调控作用。LncRNA CCAT1位于c-Myc的一个增强子区,在多种恶性肿瘤中异常表达[9],与多种恶性肿瘤的预后关系密切,如CCAT1可靶向miR-219a调节宫颈癌HeLa细胞生长、侵袭和迁移[10];激活CCAT1可通过调节SPRY4和HOXB13在食管鳞状细胞癌中的表达影响食管鳞状细胞癌细胞增殖和迁移[11];LncRNA CCAT1可被c-Myc激活促进胰腺癌细胞增殖和迁移[12]。潘洪丽等[13]对子宫内膜癌细胞中LncRNA CCAT1表达研究发现:子宫内膜癌组织中LncRNA CCAT1呈高水平表达,沉默子宫内膜癌细胞中LncRNA CCAT1水平可抑制子宫内膜癌细胞的侵袭和迁移。本文作者对子宫内膜癌Ishiwaka细胞中LncRNA CCAT1水平研究发现:Ishiwaka细胞中LncRNA CCAT1 mRNA表达水平升高,沉默Ishiwaka细胞LncRNA CCAT1表达可抑制子宫内膜癌细胞的增殖、侵袭和迁移能力。但LncRNA CCAT1在子宫内膜癌中的作用机制尚不清楚。

多种信号通路参与子宫内膜癌的发生发展过程,其中TGF-β/Smad信号通路为子宫内膜癌细胞增殖、侵袭和迁移过程中的重要通路之一。TGF-β/Smad信号通路在肿瘤的发生发展中发挥抑制和促进肿瘤进展的双重作用,在恶性肿瘤的起始阶段,TGF-β/Smad信号通路可抑制恶性肿瘤细胞增殖、促进肿瘤细胞凋亡,从而抑制恶性肿瘤的发展;在恶性肿瘤的晚期,TGF-β/Smad信号通路可促进肿瘤细胞增殖、抑制肿瘤细胞凋亡,从而促进恶性肿瘤的进展和转移过程[14]。TGF-β/Smad信号通路在恶性肿瘤的发生发展中,通过调节上皮间质转化(EMT)导致恶性肿瘤细胞免疫逃避、细胞转移和诱导血管生成等,促进恶性肿瘤的进展[15-16]

LncRNA CCAT1可通过多种信号通路参与恶性肿瘤的发生发展,如LncRNA CCAT1通过激活丝裂原活化蛋白激酶(mitogen-activated protein kinases,MAPK)信号通路影响胃癌细胞的增殖、凋亡、侵袭和迁移过程[17];LncRNA CCAT1在恶性肿瘤中的作用与CCAT1可影响恶性肿瘤细胞EMT有关[18];LncRNA CCAT1通过miR-490-3p上调TGF-β受体1从而促进TGF-β1诱导的卵巢癌细胞EMT[19]。LncRNA CCAT1可通过TGF-β诱导细胞EMT,EMT在细胞的侵袭迁移中发挥重要作用[20],因此推测LncRNA CCAT1在子宫内膜癌细胞增殖、侵袭和迁移中的作用可能与TGF-β/Smad信号通路及EMT有关。本研究结果显示:沉默CCAT1及加入TGF-β/Smad信号抑制剂均可降低细胞中PCNA、E-cadherin、vimentin、snail、Twist、p-Smad2/3和TGF-β1蛋白表达水平,细胞中E-cadherin蛋白表达水平升高。PCNA在细胞核中合成,检测细胞中PCNA蛋白水平可用于评价细胞的增殖状态[21]。E-cadherin为重要的维持上皮细胞表型的细胞间黏附分子,E-cadherin表达缺失或者表达降低是EMT的重要标志[22]。Vimentin为间质细胞的标志物,其水平升高也是EMT的标志物[23]。snail和Twist为TGF-β/Smad信号通路的上游转录因子,二者水平升高可促进TGF-β/Smad信号通路激活[24-25]。p-Smad2/3和TGF-β1蛋白表达水平可反映TGF-β/Smad信号通路状况,p-Smad2/3和TGF-β1蛋白表达水平升高表明TGF-β/Smad信号通路激活;反之,p-Smad2/3和TGF-β1蛋白水平降低表明TGF-β/Smad信号通路受到抑制。因此,本研究中沉默CCAT1及加入TGF-β/Smad信号抑制剂均可抑制子宫内膜癌细胞增殖、侵袭和迁移,降低细胞中PCNA、E-cadherin、vimentin、snail、Twist、p-Smad2/3和TGF-β1蛋白表达水平,细胞中E-cadherin蛋白表达水平升高,表明沉默CCAT1抑制子宫内膜癌细胞增殖、侵袭和迁移的机制可能与抑制TGF-β/Smad信号通路激活、从而抑制子宫内膜癌细胞EMT有关。

综上所述,沉默LncRNA CCAT1对子宫内膜癌细胞的增殖、侵袭和迁移具有抑制作用,其机制可能与沉默LncRNA CCAT1可抑制子宫内膜癌细胞TGF-β/Smad信号通路活化从而抑制EMT有关。

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