沉默减数分裂内切酶1(EME1)抑制肝癌细胞增殖的机制

Silencing essential meiotic endonuclease 1 inhibits the proliferation of liver cancer cells:A study of related mechanisms

目的探讨减数分裂内切酶1(EME1)在肝癌组织中的表达及其对肝癌细胞生物学行为的影响。方法筛选TCGA数据库肝癌样本中的差异表达基因。采用免疫组化和Western Blot分析EME1在肝癌组织中的表达丰度。通过短发夹RNA(shRNA)构建慢病毒并感染BEL-7404细胞干扰EME1基因表达,分为沉默组(shEME1)和对照组(shCtrl)。通过实时荧光定量PCR法和Western Blot检测两组EME1 mRNA和蛋白表达水平,Celigo计数法及MTT活性检测细胞增殖率,流式细胞术检测细胞周期,Caspase3/7活性检测细胞凋亡。两组间比较采用成组t检验。结果TCGA结果显示EME1的mRNA表达水平在肝癌组织中是癌旁组织的18.9倍(114.5±153.0 vs 8.0±7.2,t=5.00,P<0.001);EME1的蛋白表达水平在肝癌组织中是癌旁组织的7.0倍(免疫组化检测,8.4±2.6 vs 1.2±0.4,t=7.55,P<0.001)和2.5倍(Western Blot检测,249.0%±35.5%vs 100.0%±77.8%,t=3.02,P<0.05)。慢病毒感染后,相对于对照组,沉默组EME1的mRNA表达水平下降了29.9%(29.9%±0.9%vs 100.0%±3.6%,t=32.82,P<0.001),蛋白表达水平显著下降了35.7%(35.7%±14.9%vs 100.0%±28.9%,t=3.42,P<0.05);细胞计数下降了45.1%(4053±167 vs 8988±477,t=16.91,P<0.001)、细胞活性下降至66.9%(0.518±0.046 vs 0.774±0.022,t=8.74,P<0.001)及细胞克隆形成能力下降至29.0%(75±6 vs 260±9,t=28.92,P<0.001)。与对照组比较,沉默组G1期细胞(49.9%vs 44.0%,t=8.96,P<0.001)比例增多,G2/M期(15.9%vs 17.9%,t=9.13,P<0.001)与S期(34.2%vs 38.1%,t=6.91,P<0.001)的细胞比例减少;Caspase3/7活性增强了1.5倍(145.8%±5.9%vs 100.0%±2.3%,t=12.50,P<0.001)。结论EME1在肝癌组织中高表达,沉默EME1基因可抑制肝癌细胞增殖,促进细胞凋亡。

Objective To investigate the expression of essential meiotic endonuclease 1(EME1)in liver cancer tissue and effect on the biological behavior of hepatoma cells.Methods The TCGA database was used to identify the differentially expressed genes between liver cancer tissue and paracancerous tissue.Immunohistochemistry and Western Blot were used to measure the expression abundance of EME1 in liver cancer tissue.A lentivirus was constructed by short hairpin RNA,and BEL-7404 cells were transfected with the lentivirus to interfere with the expression of the EME1 gene;the cells were divided into silencing group(shEME1 group)and control group(shCtrl group).Quantitative real-time PCR and Western Blot were used to measure the mRNA and protein expression levels of EME1;Celigo Image Cytometer and MTT assay were used to measure cell proliferation rate;flow cytometry was used to observe cell cycle;Caspase 3/7 activity was used to measure cell apoptosis.The independent-samples t-test was used for comparison between two groups.Results TCGA results showed that the mRNA expression level of EME1 in liver cancer tissue was 18.9 times that in paracancerous tissue(t=5.00,P<0.001),and the protein expression level of EME1 in liver cancer tissue was 7.0 times(based on immunohistochemistry:8.4±2.6 vs 1.2±0.4,t=7.55,P<0.001)or 2.5 times(based on Western Blot:249.0%±35.5%vs 100.0%±77.8%,t=3.02,P<0.05)that in paracancerous tissue.After lentivirus infection,compared with the shCtrl group,the shEME1 group had an mRNA expression level of EME1 reduced by 29.9%(29.9%±0.9%vs 100.0%±3.6%,t=32.82,P<0.001),a protein expression level of EME1 reduced by 35.7%(35.7%±14.9%vs 100.0%±28.9%,t=3.42,P<0.05),and a level of cell counting reduced by 45.1%(4053±167 vs 8988±477,t=16.91,P<0.001),as well as a level of cell activity reduced to 66.9%(0.518±0.046 vs 0.774±0.022,t=8.74,P<0.001)and a level of colony forming ability reduced to 29.0%(75±6 vs 260±9,t=28.92,P<0.001).Compared with the shCtrl group,the shEME1 group had a significant increase in the proportion of cells in G1 phase(49.9%vs 44.0%,t=8.96,P<0.001)and significant reductions in the proportion of cells in G2/M phase(15.9%vs 17.9%,t=9.13,P<0.001)and S phase(34.2%vs 38.1%,t=6.91,P<0.001),while Caspase 3/7 activity was enhanced by 1.5 times(145.8%±5.9%vs 100.0%±2.3%,t=12.50,P<0.001).Conclusion EME1 is highly expressed in liver cancer tissue,and silencing the EME1 gene can inhibit the proliferation of hepatoma cells and promote cell apoptosis.