自噬基因beclin1对子宫颈癌HeLa细胞生长的作用及其机制
Effect and mechanism of an autophagy gene beclin 1 on cervical cancer HeLa cells
目的 研究自噬基因beclin 1对宫颈癌细胞株HeLa细胞生长的抑制作用,并探讨其可能的机制.方法 实验分为5组:(1)pcDNA3.1(+)-beclin 1组:转染重组载体pcDNA3.1(+)-beclin 1质粒(过度表达beclin 1基因)的HeLa细胞;(2)pSUPER-beclin 1组:转染重组载体pSUPER-beclin 1质粒的HeLa细胞(抑制Beclin 1基因表达);(3)pcDNA3.1(+)组:转染空载体pcDNA3.1(+)质粒的HeLa细胞;(4)pSUPER组:转染空载体pSUPER质粒的HeLa细胞;(5)空白对照组:未转染质粒的HeLa细胞.采用逆转录(RT)PCR技术和蛋白印迹法检测各组细胞中beclin 1 mRNA和蛋白的表达以及凋亡因子--半胱氨酸天冬氨酸蛋白酶9(caspase-9)mRNA及蛋白的表达;四甲基偶氮唑蓝(MTT)比色法检测各组细胞的生长情况;流式细胞仪检测各组细胞的凋亡率;电镜观察和流式细胞仪检测各组细胞的自噬情况.将各组细胞分别接种于裸鼠皮下,观察各组裸鼠体内的成瘤性及肿瘤生长情况.结果 (1)各组细胞中beclin 1、caspase-9 mRNA和蛋白的表达:pcDNA3.1(+)-beclin 1组beclin 1和caspase-9 mRNA的表达水平分别为994.72±468.76和12.88±2.71,pSUPER-beclin 1组分别为0.18±0.63和0.11±0.08,pcDNA3.1(+)组分别为0.57±0.12和4.28±3.25,pSUPER组分别为0.67±0.29和2.77±1.27,空白对照组分别为0.74±0.25和3.67±3.78,pcDNA3.1(+)-beclin 1组均明显高于pcDNA3.1(+)组、pSUPER组和空白对照组,pSUPER-beclin 1组均明显低于pcDNA3.1(+)组、pSUPER组和空白对照组,差异均有统计学意义(P<0.05).各组细胞中beclin 1和caspase-9蛋白的表达情况与mRNA相似.(2)各组细胞的生长情况:pcDNA3.1(+)-beclin 1组细胞的生长明显慢于空白对照组及pcDNA3.1(+)组,而pSUPER-beclin 1组细胞的生长明显快于空白对照组及pSUPER组,差异均有统计学意义(P<0.05).(3)各组细胞的凋亡率:pcDNA3.1(+)-beclin 1组为(28.2±2.3)%,pcDNA3.1(+)组为(14.6±4.6)%,pSUPER-beclin 1组为(5.7±2.0)%,pSUPER组为(16.2±3.1)%,空白对照组为(11.2±3.0)%,pcDNA3.1(+)-beclin 1组和pSUPER-beclin 1组分别与另外3组比较,差异均有统计学意义(P<0.05).(4)各组细胞的自噬情况:pcDNA3.1(+)-beclin 1组细胞内可见自噬体的形成,而其余各组自噬体形成不明显.pcDNA3.1(+)-beclin 1组自噬率为(10.3±1.5)%,pcDNA3.1(+)组为(3.6±0.8)%,pSUPER-beclin 1组为(1.2±0.3)%,pSUPER组为(3.2±1.2)%,空白对照组为(2.2±1.1)%,pcDNA3.1(+)-beclin 1组和pSUPER-beclin 1组分别与另外3组比较,差异均有统计学意义(P<0.05).(5)各组裸鼠的成瘤情况:pcDNA3.1(+)-beclin 1组裸鼠成瘤时间长于空白对照组、pcDNA3.1(+)组和pSUPER组.pSUPER-beclin 1组裸鼠肿瘤体积第7天开始明显大于空白对照组、pcDNA3.1(+)组和pSUPER组(P<0.05);pcDNA3.1(+)-beclin 1组第21天开始明显小于空白对照组、pcDNA3.1(+)组和pSUPER组(P<0.05).接种第28天,pSUPER-beclin 1组肿瘤质量为(0.52±0.08)g,明显高于空白对照组的(0.37±0.12)g和pSUPER组的(0.34±0.24)g(P<0.05);pcDNA3.1(+)-beclin 1组肿瘤质量为(0.18±0.12)g,明显低于空白对照组和pcDNA3.1(+)组的(0.34±0.18)g(P<0.05).结论 自噬基因beclin 1可以抑制宫颈癌HeLa细胞体内、外的生长,这种作用不仅与自噬调控通路有关,而且可能通过调控caspse-9基因的表达参与内源性细胞凋亡通路的调节,为宫颈癌基因治疗提供了新途径.
更多Objective To investigate the inhibitory effects and the mechanism of autophagy gene beclin 1 on cervical cancer HeLa cells. Methods The eukaryotic expression vector and short hairpin RNA (shRNA) expression vector of beclin 1 were transfected via lipofectamine into HeLa cells. Experimental cells were classified into 5 groups: pcDNA3. 1 ( + )-beclin 1 group, pSUPER-beclin 1 group, pcDNA3.1 ( + )group, pSUPER group and HeLa group. Real time-PCR and western blot were used for detecting expression of mRNA and protein of beclin 1 and caspase-9 in transfected cells. Flow cytometry was employed to observe the effect of transfection on the apoptosis, and autophagy of HeLa, while proliferation was analyzed by methyl thiazolyl tetrazolium (MTT) assay. The ultrastructural analysis of autophagic vacuoles was under the electron microscope. Five groups cells were seeded subcutaneously on nude mice. The carcinogenic and growth activities of cancer cells in vivo were observed, and immunohistochemistry was used to detect the protein expression of beclin 1 in tumor tissue. Results ( 1 ) The mRNA expression of beclin 1 and caspase-9: pcDNA3. 1 ( + )-beclin 1 group were 994.72 ±468.76 and 12. 88 ±2. 71, pSUPER-beclin 1 group were 0. 18 ± 0. 63 and 0. 11 ± 0. 08, pcDNA3. 1 ( + ) group were 0. 57 ± 0. 12 and 4. 28 ± 3. 25,pSUPER group were 0. 67 ± 0. 29 and 2. 77 ± 1.27, and HeLa group were 0. 74 ± 0. 25 and 3.67 ± 3.78,respectively. The eukaryotic expression vector pcDNA3. 1 ( + ) -beclin 1 significantly improved the expression of mRNA of beclin 1 and caspase-9 in HeLa cells( P <0. 05 ), and the shRNA expression vector inhibited the expression of mRNA of beclin 1 and caspase-9 ( P < 0.05 ). (2) The cell proliferations: pcDNA3.1 ( + ) -beclin 1 vector significantly inhibited the growth of HeLa cells, while pSUPER-beclin 1 vector significantly improved the growth of HeLa cells(P <0. 05). (3) The rate of apoptosis: pcDNA3.1 ( + )-beclin 1 group was (28.2 ±2.3)%, pcDNA3. 1( + ) group was(14.6 ±4.6)%,pSUPER-beclin 1 group was(5.7 ±2. 0) %, pSUPER group was( 16. 2 ± 3.1 ) %, and HeLa group was( 11.2 ± 3. 0) %. The pcDNA3. 1 ( + ) -beclin 1 vector significantly increased the apoptosis rate, while the pSUPER-beclin 1 vector significantly decreased the apoptosis rate(P <0. 05 ). (4)The activity of autophagy: more autophagy cells were identified in pcDNA3.1( + )-beclin 1 group; the rate of autophagy of five group were( 10. 3 ± 1.5)% in pcDNA3. 1 ( + ) -beclin 1 group, ( 3.6 ± 0. 8 ) % in pcDNA3. 1 ( + ) group, ( 1.2 ± 0. 3 ) % in pSUPER-beclin 1 group, (3.2 ± 1.2)% in pSUPER group and (2.2 ± 1. 1)% in HeLa group, there was statistical significances between test groups and control groups( P < . 05 ). (5)Carcinogenic activity of HeLa cells in nude mice: the duration of tumorigenesis was the longest in pcDNA3.1 ( + )-beclin 1 group and the shortest in pSUPER-beclin 1 group among all groups. The tumor size began to grow larger from 7th day after injection in pSUPER-beclin 1 group than in control groups( P < 0. 05 ). The tumor size was smaller from 21st day after injection in pcDNA3.1( + )-beclin 1 group than in control groups(P <0. 05). From 28th day after injection,the tumor weigh was (0. 52 ± 0. 08 )g in pSUPER-beclin 1 group, apparently more than HeLa group (0. 37 ±0. 12) g and pSUPER group (0. 34 ± 0. 24 ) g ( P < 0. 05 ). While in pcDNA3. 1 ( + )-beclin 1 group the tumor weighed (0. 18 ±0. 12) g, which was lower than HeLa group and pcDNA3. 1 ( + ) group (0. 34 ± 0. 18 ) g ( P < 0. 05 ) . Conclusions Autophagy gene beclin 1 overexpression can inhibit proliferation and growth of HeLa cells in vitro and in vivo. Beclin 1 not noly participate in the regulation of autophagy signaling, but also play an important role in the regulation of endogenous apoptosis signaling through caspase-9. So it might be one of the new strategies for gene therapy of cervical carcinoma.
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