Bmi-1 is a member of the Polycomb repressor complex 1 that mediates gene silencing by regulating chromatin structure and is indispensable for self-renewal of both normal and cancer stem cells.Despite three decades of ...Bmi-1 is a member of the Polycomb repressor complex 1 that mediates gene silencing by regulating chromatin structure and is indispensable for self-renewal of both normal and cancer stem cells.Despite three decades of research that have elucidated the transcriptional regulation,post-translational modifications and functions of Bmi-1 in regulating the DNA damage response,cellular bioenergetics,and pathologies,the entire potential of a protein with such varied functions remains to be realized.This review attempts to synthesize the current knowledge on Bmi-1 with an emphasis on its role in both normal physiology and cancer.Additionally,since cancer stem cells are emerging as a new paradigm for therapy resistance,the role of Bmi-1 in this perspective is also highlighted.The wide spectrum of malignancies that implicate Bmi-1 as a signature for stemness and oncogenesis also make it a suitable candidate for therapy.Nonetheless,new approaches are vitally needed to further characterize physiological roles of Bmi-1 with the long-term goal of using Bmi-1 as a prognostic marker and a therapeutic target.展开更多
AIM:To evaluate the impact of Bmi-1 on cell senescence and metastasis of human gastric cancer cell line BGC823.METHODS:Two pairs of complementary small hairpin RNA(shRNA)oligonucleotides targeting the Bmi-1gene were d...AIM:To evaluate the impact of Bmi-1 on cell senescence and metastasis of human gastric cancer cell line BGC823.METHODS:Two pairs of complementary small hairpin RNA(shRNA)oligonucleotides targeting the Bmi-1gene were designed,synthesized,annealed and cloned into the pRNAT-U6.2 vector.After DNA sequencing to verify the correct insertion of the shRNA sequences,the recombinant plasmids were transfected into BGC823 cells.The expression of Bmi-1 mRNA and protein was examined by reverse transcription-polymerase chain reaction(RT-PCR)and Western blotting.The effects of Bmi-1 knockdown on cell senescence and metastasis were determined by theβ-Gal activity assay and Boyden chamber assay,respectively.RESULTS:The double-stranded oligonucleotide fragments of Bmi-1 short interfering RNA(siRNA)cloned into pRNAT-U6.2 vector conformed to the inserted sequence.RT-PCR and Western blotting indicated that the expression levels of Bmi-1 gene mRNA and protein were markedly decreased in transfected BGC823 cells with pRNAT-U6.2-si1104 and pRNATU6.2-si1356,especially in transfected BGC823 cells with pRNAT-U6.2-si1104,compared with two control groups(empty vector and blank group).In particular,Bmi-1 protein expression was almost completely abolished in cells transfected with the recombinant vector harboring shRNA targeting the sequence GGAGGAGGTGAATGATAAA(nt1104-1122).Compared with untransfected cells and cells transfected with the empty vector,the mean percentage of senescent cells increased and the number of cells passing through the Matrigel decreased in cells transfected with the recombinant vectors.CONCLUSION:Silencing Bmi-1 by RNA interference can increase the senescent cell rate and effectively reduce the metastasis of gastric cancer cells.展开更多
AIM: To investigate the potential roles of enhancer of zeste homolog2(EZH2), Bmi-1 and mi R-203 in cell proliferation and invasion in hepatocellular carcinoma(HCC) cell line Hep3 B.METHODS: A total of 73 patients who ...AIM: To investigate the potential roles of enhancer of zeste homolog2(EZH2), Bmi-1 and mi R-203 in cell proliferation and invasion in hepatocellular carcinoma(HCC) cell line Hep3 B.METHODS: A total of 73 patients who underwent surgical resection at Fuzong Clinical Medical College of Fujian Medical University were enrolled in this study. Hep3 B cells were cultivated in RPMI 1640 medium supplemented with 10% fetal bovine serum at 37?℃. Vectors that containing c DNA of the EZH2 gene or mi R-203 targeted sh RNA plasmid were constructed, and then transfected into Hep3 B cells. The m RNA expression of mi R-203, EZH2, and Bmi-1 was analyzed using quantitative real-time polymerase chain reaction analysis, and the protein levels of EZH2 and Bmi-1 were detected by Western blot analysis. Effect of EZH2 or mi R-203 on cell proliferation was observed by methyl thiazolyl tetrazolium assay, and cell apoptosis was assessed using flow cytometry. Besides, effect of EZH2 or mi R-203 on tumor cell invasion was detected using Transwell assay.RESULTS: The m RNA levels of EZH2 and Bmi-1 in HCC tissues and in Hep3 B cells were significantly higher compared with those in normal samples(P < 0.01), while mi R-203 level was significantly lower in HCC tissues(P < 0.01). Hep3 B cells transfected with EZH2-sh RNA or mi R-203-sh RNA showed lower expression levels of EZH2 and Bmi-1(P < 0.05). Compared with controls, Hep3 B cells transfected with EZH2-sh RNA had relative slow cell proliferation, indicating that low expression of EZH2 and Bmi-1 and overexpression of mi R-203 could inhibit Hep3 B cell proliferation(P < 0.05). The average apoptosis rate of Hep3 B cells transfected with EZH2-sh RNA vector was about 18.631%, while that of Hep3 B cells transfected with sh RNA vector was about 5.33%, suggesting that EZH2 was down-regulated by transfecting with EZH2-sh RNA, and the down-regulated EZH2 contributed to the cell apoptosis. Low expression of EZH2 and Bmi-1 and overexpression of mi R-203 could reduce Hep3 B cell invasion(P < 0.05).CONCLUSION展开更多
Liver is the most common metastatic site for colorectal cancer(CRC),there is no satisfied approach to treat CRC liver metastasis(CRCLM).Here,we investigated the role of a polycomb protein BMI-1 in CRCLM.Immunohistoche...Liver is the most common metastatic site for colorectal cancer(CRC),there is no satisfied approach to treat CRC liver metastasis(CRCLM).Here,we investigated the role of a polycomb protein BMI-1 in CRCLM.Immunohistochemical analysis showed that BMI-1 expression in liver metastases was upregulated and associated with T4 stage,invasion depth and right-sided primary tumor.Knockdown BMI-1 in high metastatic HCT116 and LOVO cells repressed the migratory/invasive phenotype and reversed epithelialemesenchymal transition(EMT),while BMI-1 overexpression in low metastatic Ls174 T and DLD1 cells enhanced invasiveness and EMT.The effects of BMI-1 in CRC cells were related to upregulating snail via AKT/GSK-3βpathway.Furthermore,knockdown BMI-1 in HCT116 and LOVO cells reduced CRCLM using experimental liver metastasis mice model.Meanwhile,BMI-1 overexpression in Ls174 T and DLD1 significantly increased CRCLM.Moreover,sodium butyrate,a histone deacetylase and BMI-1 inhibitor,reduced HCT116 and LOVO liver metastasis in immunodeficient mice.Our results suggest that BMI-1 is a major regulator of CRCLM and provide a potent molecular target for CRCLM treatment.展开更多
Background Bmi-1 gene determines the proliferative capacity of normal and leukemia stem cells. Expression of Bmi-1 has been found in all types of myeloid leukemia cells in both humans and mice. This study aimed at ass...Background Bmi-1 gene determines the proliferative capacity of normal and leukemia stem cells. Expression of Bmi-1 has been found in all types of myeloid leukemia cells in both humans and mice. This study aimed at assessing the effect of antisense Bmi-1 expression on K562 cells proliferation and p16 protein （p16） expression. Methods A transcriptional repressor, Bmi-1 cDNA was cloned by reverse transcriptase polymerase chain reaction （RT-PCR） of its mRNA from K562 cells. A plasmid expressing antisense Bmi-1 mRNA was then constructed by reverse design of PCR primers and cloned to the plasmid pLNCX2; G418 was added to the medium after the plasmid was successfully introduced in K562 cells by lipofectin-mediated DNA transfection. The effects of the antisense expression on the proliferation of K562 cells were analyzed by using microcuhure tetrazolium and colony forming. Cell cycle was analyzed by using flow cytometry. The p16 expression of K562 cells was observed by immunoflorescence histochemical stain. Results K562 cells transfected with antisense Bmi-1 plasmid grew significantly slower than that of controls （the parental K562 and cells transfected with empty plasmid）. The colony forming ability of antisense Bmi-1 plasmid transfected ceils decreased significantly （P 〈0. O1 ） compared with controls. The p16 expression of cells transfected with antisense Bmi-1 was upgraded more apparently than that of controls. Conclusion The antisense Bmi-1 gene can inhibit the growth of K562 cell and upgrade expression of p16 in K562 cells.展开更多
基金This study was supported by the National Institutes of Health(NIH)CA157481 awarded to RB.
文摘Bmi-1 is a member of the Polycomb repressor complex 1 that mediates gene silencing by regulating chromatin structure and is indispensable for self-renewal of both normal and cancer stem cells.Despite three decades of research that have elucidated the transcriptional regulation,post-translational modifications and functions of Bmi-1 in regulating the DNA damage response,cellular bioenergetics,and pathologies,the entire potential of a protein with such varied functions remains to be realized.This review attempts to synthesize the current knowledge on Bmi-1 with an emphasis on its role in both normal physiology and cancer.Additionally,since cancer stem cells are emerging as a new paradigm for therapy resistance,the role of Bmi-1 in this perspective is also highlighted.The wide spectrum of malignancies that implicate Bmi-1 as a signature for stemness and oncogenesis also make it a suitable candidate for therapy.Nonetheless,new approaches are vitally needed to further characterize physiological roles of Bmi-1 with the long-term goal of using Bmi-1 as a prognostic marker and a therapeutic target.
基金Supported by The Provincial Nature Science Foundation of Henan Education Department,No.2009C310007,to Gao FL
文摘AIM:To evaluate the impact of Bmi-1 on cell senescence and metastasis of human gastric cancer cell line BGC823.METHODS:Two pairs of complementary small hairpin RNA(shRNA)oligonucleotides targeting the Bmi-1gene were designed,synthesized,annealed and cloned into the pRNAT-U6.2 vector.After DNA sequencing to verify the correct insertion of the shRNA sequences,the recombinant plasmids were transfected into BGC823 cells.The expression of Bmi-1 mRNA and protein was examined by reverse transcription-polymerase chain reaction(RT-PCR)and Western blotting.The effects of Bmi-1 knockdown on cell senescence and metastasis were determined by theβ-Gal activity assay and Boyden chamber assay,respectively.RESULTS:The double-stranded oligonucleotide fragments of Bmi-1 short interfering RNA(siRNA)cloned into pRNAT-U6.2 vector conformed to the inserted sequence.RT-PCR and Western blotting indicated that the expression levels of Bmi-1 gene mRNA and protein were markedly decreased in transfected BGC823 cells with pRNAT-U6.2-si1104 and pRNATU6.2-si1356,especially in transfected BGC823 cells with pRNAT-U6.2-si1104,compared with two control groups(empty vector and blank group).In particular,Bmi-1 protein expression was almost completely abolished in cells transfected with the recombinant vector harboring shRNA targeting the sequence GGAGGAGGTGAATGATAAA(nt1104-1122).Compared with untransfected cells and cells transfected with the empty vector,the mean percentage of senescent cells increased and the number of cells passing through the Matrigel decreased in cells transfected with the recombinant vectors.CONCLUSION:Silencing Bmi-1 by RNA interference can increase the senescent cell rate and effectively reduce the metastasis of gastric cancer cells.
文摘AIM: To investigate the potential roles of enhancer of zeste homolog2(EZH2), Bmi-1 and mi R-203 in cell proliferation and invasion in hepatocellular carcinoma(HCC) cell line Hep3 B.METHODS: A total of 73 patients who underwent surgical resection at Fuzong Clinical Medical College of Fujian Medical University were enrolled in this study. Hep3 B cells were cultivated in RPMI 1640 medium supplemented with 10% fetal bovine serum at 37?℃. Vectors that containing c DNA of the EZH2 gene or mi R-203 targeted sh RNA plasmid were constructed, and then transfected into Hep3 B cells. The m RNA expression of mi R-203, EZH2, and Bmi-1 was analyzed using quantitative real-time polymerase chain reaction analysis, and the protein levels of EZH2 and Bmi-1 were detected by Western blot analysis. Effect of EZH2 or mi R-203 on cell proliferation was observed by methyl thiazolyl tetrazolium assay, and cell apoptosis was assessed using flow cytometry. Besides, effect of EZH2 or mi R-203 on tumor cell invasion was detected using Transwell assay.RESULTS: The m RNA levels of EZH2 and Bmi-1 in HCC tissues and in Hep3 B cells were significantly higher compared with those in normal samples(P < 0.01), while mi R-203 level was significantly lower in HCC tissues(P < 0.01). Hep3 B cells transfected with EZH2-sh RNA or mi R-203-sh RNA showed lower expression levels of EZH2 and Bmi-1(P < 0.05). Compared with controls, Hep3 B cells transfected with EZH2-sh RNA had relative slow cell proliferation, indicating that low expression of EZH2 and Bmi-1 and overexpression of mi R-203 could inhibit Hep3 B cell proliferation(P < 0.05). The average apoptosis rate of Hep3 B cells transfected with EZH2-sh RNA vector was about 18.631%, while that of Hep3 B cells transfected with sh RNA vector was about 5.33%, suggesting that EZH2 was down-regulated by transfecting with EZH2-sh RNA, and the down-regulated EZH2 contributed to the cell apoptosis. Low expression of EZH2 and Bmi-1 and overexpression of mi R-203 could reduce Hep3 B cell invasion(P < 0.05).CONCLUSION
基金supported by the National Natural Science Foundation of China(Nos.81272493 and 81472213)the Health Commission of Zhejiang Province(Nos.2019331258 and 2019335600,China)+1 种基金Natural Sciences Foundation of Zhejiang Province(No.LY17H220001,China)the Science Technology Department of Zhejiang Province(Nos.LGF20H220001 and 2015C37112,China)。
文摘Liver is the most common metastatic site for colorectal cancer(CRC),there is no satisfied approach to treat CRC liver metastasis(CRCLM).Here,we investigated the role of a polycomb protein BMI-1 in CRCLM.Immunohistochemical analysis showed that BMI-1 expression in liver metastases was upregulated and associated with T4 stage,invasion depth and right-sided primary tumor.Knockdown BMI-1 in high metastatic HCT116 and LOVO cells repressed the migratory/invasive phenotype and reversed epithelialemesenchymal transition(EMT),while BMI-1 overexpression in low metastatic Ls174 T and DLD1 cells enhanced invasiveness and EMT.The effects of BMI-1 in CRC cells were related to upregulating snail via AKT/GSK-3βpathway.Furthermore,knockdown BMI-1 in HCT116 and LOVO cells reduced CRCLM using experimental liver metastasis mice model.Meanwhile,BMI-1 overexpression in Ls174 T and DLD1 significantly increased CRCLM.Moreover,sodium butyrate,a histone deacetylase and BMI-1 inhibitor,reduced HCT116 and LOVO liver metastasis in immunodeficient mice.Our results suggest that BMI-1 is a major regulator of CRCLM and provide a potent molecular target for CRCLM treatment.
文摘Background Bmi-1 gene determines the proliferative capacity of normal and leukemia stem cells. Expression of Bmi-1 has been found in all types of myeloid leukemia cells in both humans and mice. This study aimed at assessing the effect of antisense Bmi-1 expression on K562 cells proliferation and p16 protein （p16） expression. Methods A transcriptional repressor, Bmi-1 cDNA was cloned by reverse transcriptase polymerase chain reaction （RT-PCR） of its mRNA from K562 cells. A plasmid expressing antisense Bmi-1 mRNA was then constructed by reverse design of PCR primers and cloned to the plasmid pLNCX2; G418 was added to the medium after the plasmid was successfully introduced in K562 cells by lipofectin-mediated DNA transfection. The effects of the antisense expression on the proliferation of K562 cells were analyzed by using microcuhure tetrazolium and colony forming. Cell cycle was analyzed by using flow cytometry. The p16 expression of K562 cells was observed by immunoflorescence histochemical stain. Results K562 cells transfected with antisense Bmi-1 plasmid grew significantly slower than that of controls （the parental K562 and cells transfected with empty plasmid）. The colony forming ability of antisense Bmi-1 plasmid transfected ceils decreased significantly （P 〈0. O1 ） compared with controls. The p16 expression of cells transfected with antisense Bmi-1 was upgraded more apparently than that of controls. Conclusion The antisense Bmi-1 gene can inhibit the growth of K562 cell and upgrade expression of p16 in K562 cells.
