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Objective To investigate the effects of human papilloma virus 16 E6 (HPV16 E6) on endoplasmic reticulum (ER) stress-autophagic response in the cervical cancer C33A cells.Methods Polymerase chain reaction was used for detecting the integration of HPV DNA.The eukaryotic expression vector of HPV16 E6 was constructed and transfected via lipofectamine into C33A cells.Experimental cells were classified into 3 groups:pcDNA3.1--HPV16 E6 group,pcDNA 3.1-group and C33A group.Western blot was used to measure expression of protein of HPV16 E6,Beclin 1,LC3 Ⅱ,IRE1,PERK and ATF6 in transfected cells.Results here was no HPV DNA integration in C33A cells that were confirmed as the intervention cells.Eukaryotic expression vector pcDNA3.1--HPV16 E6 was constructed successfully.The eukaryotic expression vector pcDNA3.1--HPV16 E6 significantly improved the expression of protein of HPV 16 E6 in C33A cells.The protein expression of Beclin 1,LC3 Ⅱ,IRE1,PERK and ATF6 were significantly improved after transfection with vector pcDNA3.1 +-HPV16 E6 (P ＜ 0.05).Furthermore,LC3 Ⅱ protein level was reduced by treatment with ER stress inhibitor.Conclusion HPV16 E6 can improve autophagy through the ER stress pathway,and this response may play an important role in the process of HPV16 E6 inducing cervical cancer,providing one of the new strategies for gene therapy of cervical carcinoma.
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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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The shRNA expression vectors were constructed and transfected via lipofectamine into HeLa cells. Real time-ploymerase chain reaction (RT-PCR) and Western blot were used for detecting the expression of mRNA and protein of Beclin1 in transfected cells. Flow cytometry was employed to observe the effect of transfection on the apoptosis and cell cycle of HeLa, and proliferation was analyzed by MTT assay. The expression of caspase-9 in transfection cells was also detected by RT-PCR and Western blot. The constructed vectors significantly inhibited the expressin of mRNA and the protein of Beclin1 in HeLa cells. The growth of transfected cells was promoted, and less apoptosis cells were identified in these cells. After transfection of the constructed vectors into HeLa cells, the expression of caspase-9 was effectively inhibited. All of these indicate that autophagy and apoptosis are two types of programmed cell death, that autophagy gene Beclin 1 plays an important role in these two types, and that defect of autophagy and apoptosis may be important in tumor genesis.