下调基因PTTG1表达对前列腺癌LNCaP-AI细胞增殖、侵袭和凋亡的影响

Downregulation of PTTG1 expression inhibits the proliferation and invasiveness and promotes the apoptosis of human prostate cancer LNCaP-AI cells

目的:探讨下调垂体肿瘤转化基因1(PTTG1)表达对雄激素非依赖性前列腺癌LNCa P-AI细胞增殖、侵袭、凋亡,以及对雄激素拮抗剂敏感性的影响。方法:LNCa P-AI细胞转染靶向PTTG1基因的siRNA,MTT法检测细胞增殖,Transwell法检测细胞侵袭,流式细胞术检测细胞凋亡,Western印迹检测PTTG1、p-Akt、p-ERK等蛋白表达水平,琼脂糖凝胶电泳法检测PTTG1 mRNA表达水平。结果:siRNA有效抑制了PTTG1的表达;下调PTTG1表达有效抑制了LNCa P-AI细胞在去雄激素培养液中的增殖,24、48、72 h抑制率分别为(19.47±2.12)%、(24.01±2.13)%、(48.02±2.22)%,组间比较有显著性差异(P<0.05);降低其侵袭力,Transwell试验显示,对照组、转染24、48、72 h后穿过聚碳酸酯膜细胞个数分别为111.11±13.47、74.67±9.85、56.44±8.66、37.33±6.14,组间比较有显著性差异(P<0.01);siRNA-PTTG1转染LNCa P-AI细胞后,空白对照组、转染24、48、72 h后凋亡率分别为(2.17±0.49)%、(18.32±0.94)%、(19.94±1.30)%、(21.73±1.88)%,各组间比较有显著性差异(P<0.05)。siRNA联合氟他胺组对LNCa P-AI增殖的抑制作用和促凋亡作用显著强于siRNA或者氟他胺组,并呈氟他胺浓度相关性;50 nmol/L氟他胺、siRNA联合50 nmol/L氟他胺对LNCa P-AI的抑制率分别为(27.13±3.52)%、(67.51±5.13)%,两组间比较有显著性差异(P<0.05);凋亡率分别为(3.94±0.48)%、(19.93±1.72)%,两组间比较有显著性差异(P<0.05);100 nmol/L氟他胺、siRNA联合100 nmol/L氟他胺的抑制率分别为(43.72±3.90)%、(73.19±4.78)%,两组间比较有显著性差异(P<0.05);凋亡率分别为(5.33±0.66)%、(23.43±1.76)%,两组间比较有显著性差异(P<0.05)。结论:siRNA下调PTTG1表达能够抑制LNCa P-AI的增殖和侵袭,促进凋亡,提高了LNCa P-AI细胞对雄激素拮抗剂氟他胺的敏感性,抑制PTTG1表达可能会强化雄激素剥夺治疗晚期前列腺癌的作用。

Objective ： To investigate the effects of down-regulation of PTTG1 expression on the proliferation, invasiveness and apoptosis of androgen-independent human prostate cancer LNCaP-AI cells and their sensitivity to androgen antagonists. Methods： Human prostate cancer LNCaP-AI cells were transfected with siRNA targeting the PTTG1 gene using the Lipofectamine 2000 transfec- tion reagent. The proliferation, invasiveness and apoptosis of the cells were detected by MTT, Transwell assay and flow cytomet^y, re- spectively. The protein expressions of PTTG1, p-Akt, and p-ERK were determined by Western blot and the mRNA expression of PTTG1 measured by agarose gel electrophoresis. Results： The siRNA expression vector markedly down-regulated the expression of PTFG1, which effectively suppressed the proliferation of the LNCaP-AI ceils, with the inhibition rates of （19.47 ± 2.12）, （24.01 ± 2.13 ） and （48.02 ± 2.22 ） % at 24, 48 and 72 hours, respectively, after transfection, with statistically significant differences among the three groups （P 〈 0.05 ）. The number of the cells passing through the polycarbonate film was remarkably decreased at 24, 48 and72hours （74.67 ±9.85, 56.44 ± 8.66and37.33 ± 6.14） as compared with the baseline （111.11 ± 13.47） （P 〈 0.01 ）, while the apoptosis rate of the cells was significantly increased at 24, 48 and 72 hours （ 18.32 ± 0.94）, （ 19.94 ± 1.30） and （21.73 ± 1.88） % in comparison with the baseline （ [ 2.17 ± 0.49] % ）, （P 〈 0.05）. PTTG1 siRNA combined with andro- gen antagonist flumatide exhibited even more significant effects in inhibiting the proliferation and promoting the apoptosis of the LNCaP- AI cells than either used alone, and in a flumatide dose-dependent manner. The inhibition and apoptosis rates of the LNCaP-AI cells treated with 50 nmol/L flumatide were （27.13 ±3.52） and （3.94 ± 0.48） %, and those treated with siRNA ＋ 50 nmol/L flumati- de were （67.51 ± 5.13 ） and （19.93 ± 1.72）%, respectively, both with statistically significant differences between the two groups （P 〈 0.05）. The inhibition and apoptosis rates of the cells treated with 100 nmol/L flumatide were （43.72 ±3.90） and （5.33 ± 0.66） %, and those treated with siRNA ＋ 100 nmol/L flumatide were （73.19 ± 4.78） and （23.43 ±1.76） %, respectively, both with statistically significant differences between the two groups （P 〈0. 05 ）. Conclusion： The siRNA expression vector can down- regulate the expression of PTTG1, which can inhibit the proliferation and invasiveness of LNCaP-AI cells, promote their apoptosis, and increase their sensibility to androgen antagonists. Suppressing the expression of PTTG1 may enhance the effect of androgen-deprivation therapy on advanced prostate cancer.