Polycomb group (PcG) proteins are a family of epigenetic regulators responsible for the repression of genes in proliferation and differentiation of stem cells. PcG protein complex consists of two important epigenetic regulators: PRC1 (polycomb repressive complex 1) and PRC2 (polycomb repressive complex 2). In order to further understand the functions of PcG proteins in stem cell growth and differentiation, we review the PcG protein composition, PcG protein localization in the target gene, PcG protein recruitment, and the functions of PcG proteins in the development of stem cells.
Cell Differentiation ; physiology ; Cell Proliferation ; Humans ; Polycomb Repressive Complex 1 ; metabolism ; physiology ; Polycomb Repressive Complex 2 ; metabolism ; physiology ; Polycomb-Group Proteins ; metabolism ; physiology ; Stem Cells ; cytology ; metabolism

OBJECTIVEThis study was aimed to investigate the expression and clinical significance of Bmi-1 and P14 in extranodal NK/T-cell lymphoma (ENKTCL) tissue.

METHODSMaxvision immunohistochemistry technique was used to detect the expression level of Bmi-1 and P14 in the tissues of 21 patients with ENKTCL and 11 normal lymph nodes. The correlation of Bmi-1 or P14 expression with the clinical features and the correlation between Bmi-1 and P14 expression were analyzed.

RESULTSThe expression of Bmi-1 protein was higher in tissues of ENKTCL than that in tissues of lymph nodes, and the Bmi-1 expression levels did not correlate with patients' sex, age, lactate dehydrogenase (LDH), International Prognostic Index (IPI) scores and B symptoms (P > 0.05), except for clinical stage (P < 0.05). The P14 protein expression level was lower in ENKTCL tissues than in normal lymph node tissues, which did not correlate with age, sex, LDH, IPI scores, clinical stage and B symptoms. Correlation test showed a negative correlation between Bmi-1 and P14 (r = -0.472, P = 0.031).

CONCLUSIONBmi-1 protein over-expresses in ENKTCL tissues that may display a negative-regulation effect on P14 in the genesis and progress of ENKTCL.

Genes, Tumor Suppressor ; Humans ; Lymph Nodes ; Lymphoma, Extranodal NK-T-Cell ; Oncogene Proteins ; Polycomb Repressive Complex 1

This study was aimed to construct lentivirus-mediated shRNA expression vector targeting Bmi-1 and establish a stable cell line U266-li, so as to pave the way for further research on function of Bmi-1 and application of shRNA to gene therapy. One pair of oligonucleotide sequences targeted at human Bmi-1 mRNA were designed and synthesized. The annealed oligonucleotide fragments were subcloned into pLVTHM vector. Virus particles were collected after the control or shRNA vectors were co-transfected with the psPAX2 packaging plasmid and the plasmid pMD2.G was enveloped into HEK-293T cells by using Lipofectamine2000. The U266 cells were transduced with 5 × 10(6) recombinant lentivirus-transducing units plus 6 µg/ml of polybrene. Real-time PCR and Western blot were used respectively to detect the expression of Bmi-1 and P14 after lentivirus transduction. DNA sequencing demonstrated that the lentivirus RNAi vector of Bmi-1 was constructed successfully and the virus was packaged in 293T cells. The titer of virus was 5 × 10(7) TU/ml. Stable transfected U266 cell line was established. As was expected, the mRNA and protein levels of Bmi-1 was reduced significantly in U266 cells after lentivirus transduction, whereas the mRNA and protein levels of P14 was upregulated. It is concluded that the lentiviral RNAi vector of Bmi-1 is constructed, and U266 stable cell line is established.
Cell Line, Tumor ; Genetic Vectors ; Humans ; Lentivirus ; genetics ; Polycomb Repressive Complex 1 ; genetics ; RNA Interference ; RNA, Small Interfering ; genetics

OBJECTIVE: To study whether the Bmi-1 gene can be a biomarker for analysis of clinical risk stratification and prognosis of ALL patients. METHODS: The expression level of Bmi-1 gene in bone marrow samples from 127 cases of newly diagnosed ALL was detected by qRT-PCR, at the same time the expression level of Bmi-1 protein in bone marrow samples from above-mentioned cases was detected by Western blot. The collected samples were divided into 3 groups: high, intermediate and low risk according to clinical risk stratfication, the relationship between Bmi-1 expression and risk grade of ALL patients was analyzed; at the same time the collected samples were divided into 2 groups: prednisone good response (PGR) and prednisone poor respouse (PPR) according to the sensitivity of prednison test, and the sensitivily to prednisone in 2 groups was compared; moreover, the collected samples were divided into 2 groups: high level and low level according to median of Bmi-1 level, and the relation of Bmi-1 level with prognosis of patients was analyzed by using the Kaplan-Meier method. RESULTS: The expression level of Bmi-1 in low risk group was lowest, while that in high risk group was highest, however that in intermediat risk group was between the low and high risk groups, statistical analysis showed significant difference (P＜0.05). The expression level of Bmi-1 in PPR group was significantly higher than that in PGR group (P＜0.001). The Kaplan-Meier analysis showed that the RFS rate in Bmi-1 high expression group was significantly lower than that in Bmi-1 low expression group (73.0% vs 90.6%) (P＜0.001). CONCLUSION The Bmi-1 can be used as a molecular marker for the analysis of chinical risk and prognosis of pediatric ALL.
Biomarkers ; Child ; Humans ; Kaplan-Meier Estimate ; Polycomb Repressive Complex 1 ; metabolism ; Precursor Cell Lymphoblastic Leukemia-Lymphoma ; Prednisone ; Prognosis

CRISPR-Cas Systems ; Embryo, Mammalian ; Gene Editing ; methods ; HEK293 Cells ; Humans ; Polycomb Repressive Complex 1 ; genetics ; Zygote

Adult ; Aged ; Aged, 80 and over ; Case-Control Studies ; Female ; Humans ; Male ; Middle Aged ; Multiple Myeloma ; genetics ; metabolism ; pathology ; Polycomb Repressive Complex 1 ; genetics ; metabolism ; Prognosis ; RNA, Messenger ; genetics

Recently, some plasmid vectors that direct transcription of small hairpin RNAs have been developed, which are processed into functional siRNAs by cellular enzymes. Although these vectors possess certain advantages over synthesized siRNA, many disadvantages exist, including low and variable transfection efficiency. This study was aimed to establish an adenoviral siRNA delivery system without above-mentioned disadvantages on the basis of commercially available vectors. A vector was designed to target the human polycomb gene BMI-1. The pAd-BMI-1shRNA-CMV-GFP vector was produced by cloning a 300 bp U6-BMI-1 cassette from the pGE1BMI-1shRNA plasmid and a CMV-GFP cassette from pAdTrack CMV in pShutter vector. The adenovirus was produced from the 293A packaging cell line and then infected K562 cells. The mRNA and protein levels of Bmi-1 were detected by real time-PCR and Western blot respectively. The results showed that the adenovirus carrying the BMI-1shRNA was successfully produced. After being transfected with the adenovirus, the K562 cells dramatically down-regulated BMI-1 expression, whereas the adenoviruses carrying control shRNA had no effect on BMI-1 expression. It is concluded that the adenoviruses are efficient vectors for delivery of siRNA into mammalian cells and may become a candidate vector carrying siRNA drugs for gene therapy.
Adenoviridae ; genetics ; Genetic Vectors ; Humans ; K562 Cells ; Nuclear Proteins ; genetics ; Plasmids ; Polycomb Repressive Complex 1 ; Proto-Oncogene Proteins ; genetics ; RNA, Small Interfering ; genetics ; Repressor Proteins ; genetics ; Transfection

OBJECTIVETo explore the role of Bmi-1 gene in the proliferation of squamous carcinoma cells and whether the silencing Bmi-1 can inhibit the growth of squamous cell carcinomas cells.

METHODSThe expressions of Bmi-1 in primary cultured Fibroblasts, karatinocyte cell line Hacat,squamous carcinoma cell line A431, and ECA109 were detected by reverse transcription polymerase chain reaction (RT-PCR) and Western blot analysis. Recombinant plasmid inserted with Bmi-1 gene short hairpin RNA (shRNA) expression vector PGPU6/GFP/Neo-shBmi-1 was constructed and transfected into ECA109 cells with control set. After transfection for 48 and 72 hours,the mRNA and protein levels of Bmi-1 were examined with RT-PCR and Western blot analysis, respectively. The proliferation of the ECA109 cells was evaluated by MTT method and flow cytometry.

RESULTSBmi-1 was highly expressed in A431 and ECA109 cells than in Fibroblast cells and Hacat cells. The mRNA and protein expressions of Bmi-1 were significantly silenced in ECA109 cells after recombinant expression vector PGPU6/GFP/Neo-shBmi-1 transfection (P<0.05). Compared with the control groups,the proliferation of ECA109 transfected with PGPU6/GFP/Neo-shBmi-1 was significantly inhibited (P<0.05), and cells in G1 phase increased while in S phase decreased (P<0.05).

CONCLUSIONSBmi-1 is involved in the proliferation of squamous carcinoma cells. After the silencing of Bmi-1 expression,the proliferation ECA109 cells is suppressed due to the altered cell cycle.

Blotting, Western ; Carcinoma, Squamous Cell ; Cell Cycle ; Cell Line ; Cell Proliferation ; Fibroblasts ; Flow Cytometry ; Humans ; Plasmids ; Polycomb Repressive Complex 1 ; RNA, Messenger ; RNA, Small Interfering ; Transfection

OBJECTIVETo investigate the effect of silencing Bmi-1 expression in reversing cisplatin resistance in human lung cancer cells and explore the possible mechanisms.

METHODSCisplatin-resistant A549/DDP cells with small interference RNA (siRNA)-mediated Bmi-1 expression silencing were examined for cisplatin sensitivity using MTT assay and alterations in cell cycle distribution and apoptosis with flow cytometry, and the changes in cell senescence was assessed using β-galactosidase staining. The protein expressions of Bmi-1, P14(ARF), P16(INK4a), P53, P21, Rb and ubi-H2AK119 in the cells were determined with Western blotting.

RESULTSA549/DDP cells showed significantly higher Bmi-1 expression than A549 cells. After siRNA-mediated Bmi-1 silencing, A549/DDP cells showed significantly enhanced cisplatin sensitivity with an increased IC50 from 40.3±4.1 µmol/L to 18.3±2.8 µmol/L (P<0.01) and increased cell percentage in G0/G1 phase from (48.9±2.3)% to (78.7±7.6)% (P<0.01). Silencing Bmi-1 did not cause significant changes in the cell apoptosis rate but induced obvious senescence phenotype in A549/DDP cells with down-regulated expression of ubi-H2AK119 and up-regulated expressions of P14(ARF), P16(INK4a), P53, P21 and Rb.

CONCLUSIONSilencing Bmi-1 by RNA interference can induce cell senescence and resensitize A549/DDP cells to cisplatin possibly by regulating INK4a/ARF/Rb senescence pathway.

Antineoplastic Agents ; pharmacology ; Apoptosis ; Cell Cycle ; Cell Line, Tumor ; Cisplatin ; pharmacology ; Drug Resistance, Neoplasm ; Gene Silencing ; Humans ; Lung Neoplasms ; genetics ; Polycomb Repressive Complex 1 ; genetics ; RNA, Small Interfering

OBJECTIVE: To investigate the effect of Bmi-1 gene silence on the proliferation ability of K562 cells in vitro and in vivo, and to explore the relation of molecular mechanism between proliferation ability of K562 cells in vitro and in vivo with PTEN/pAKT signaling pathway. METHODS: The Bmi-1 small interference RNA (siRNA) sequences were transfected into K562 cells for decreasing Bmi-1 expression. The effect of Bmi-1 siRNA on the proliferation of K562 cells in vitro and in vivo was detected by MTT method and colony-forming test, the effect of Bmi-1 siRNA on the tumorogenicity of K562 cells was observed by subcutaneous inoculation of K562 cells, LY294002 and Bpv treated K562 cells in nude mice, the expression of Bmi-1, PTEN and pAKT proteins were detected by Western blot. RESULTS: The Bmi-1 siRNA could inhibit the proliferation activity, colony-forming and tumor-forming abilities of K562 cells. After the silence of Bmi-1 gene, the PTEN expression in Bmi-1 gene-silenced group was significantly enhanced. While the pAKT expression in Bmi-1 gene-silenced group was significantly reduced; after the K562 cells were treated with LY294002 (an inhibitor of pAKT), the pAKT expression colony-forming and tumor forming abilities were reduced in comparison with untreated K562 cells; after the K562-S1 cells were treated with Bpv (an inhibitor of PTEN), the PTEN expression decreased, while the pAKT expression, colony forming and tumor-forming abilities were restored. CONCLUSION The Bmi-1 gene possibly involves in regulation of K562 proliferation in vivo and in vitro, the effect of PTEN/pAKT signaling pathway maybe one of molecular mechanisms mediating this regulation.
Animals ; Apoptosis ; Cell Proliferation ; Humans ; K562 Cells ; Leukemia ; Mice ; Mice, Nude ; PTEN Phosphohydrolase ; Polycomb Repressive Complex 1 ; Proto-Oncogene Proteins c-akt ; RNA, Small Interfering ; Signal Transduction