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

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

B lymphoma Moloney murine leukemia virus insertion region 1 (BMI1), a core member of polycomb repressive complex 1 (PRC1), has been intensely investigated in the field of cancer epigenetics for decades. Widely known as a critical regulator in cellular physiology, BMI1 is essential in self-renewal and differentiation in different lineages of stem cells. BMI1 also plays a significant role in cancer etiology for its involvement in pathological progress such as epithelial-mesenchymal transition (EMT) and cancer stem cell maintenance, propagation, and differentiation. Importantly, overexpression of BMI1 is predictive for drug resistance, tumor recurrence, and eventual therapy failure of various cancer subtypes, which renders the pharmacological targeting at BMI1 as a novel and promising therapeutic approach. The study on prostate cancer, a prevalent hormone-related cancer among men, has promoted enormous research advancements in cancer genetics and epigenetics. This review summarizes the role of BMI1 as an oncogenic and epigenetic regulator in tumor initiation, progression, and relapse of prostate cancer.
Animals ; Gene Expression Regulation, Neoplastic ; Humans ; Lymphoma, B-Cell/genetics* ; Male ; Mice ; Moloney murine leukemia virus/genetics* ; Mutagenesis, Insertional/genetics* ; Polycomb Repressive Complex 1/genetics* ; Prostatic Neoplasms/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

OBJECTIVE: To explore the molecular mechanism by which miR-218 targeting Bmi-1 inhibits the proliferation of acute promyelocytic leukemia (APL) cells. METHODS: APL cell line HL-60 was transfected by miR-218 and RNA-negative control sequences, respectively. The expression of miR-218 in cells was detected by real-time fluorescence quantitative PCR. The effect of transfected miR-218 on the proliferation of APL cells was detected by MTT assay. Cell apoptosis was detected by flow cytometry. The regulation effect of miR-218 on Bmi-1 expression was determined by Western blot. The correlation of miR-218 expressions with Bmi-1 was analyzed by Spearman test. The targeted relationship between miR-218 and Bmi-1 was verified by luciferase assay. RESULTS: MTT assay showed that the proliferation of HL-60 cells in vitro was inhibited by high expression miR-218 significantly. Flow cytometry showed that the G1 and G2 phase cells increased while the S phase cells decreased after transfected by miR-218. Western blot showed that the level of Bmi-1 protein in HL-60 cells decreased significantly after transfection of miR-218 (P＜0.05). Spearman correlation analysis showed that the mRNA level of miR-218 negatively correlated with the protein content of Bmi-1 (r=-0.326, P＜0.01). Luciferase assay indicated that Bmi-1 could targeted on miR-218 directly. CONCLUSION miR-218 can inhibit the proliferation, metastasis and invasion of APL cells, which can be related with the down-regulated of Bmi-1.
Apoptosis ; Cell Proliferation ; Gene Expression Regulation, Neoplastic ; HL-60 Cells ; Humans ; Leukemia, Promyelocytic, Acute ; genetics ; MicroRNAs ; genetics ; Polycomb Repressive Complex 1 ; genetics

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

OBJECTIVE: To construct the Bmi-1 RNAi expression vector and investigate its influence on the proliferation and invasiveness of laryngeal carcinoma Hep-2 cells. METHOD: The recombinant vshRNA-Bmi-1 plasmid of Bmi-1 RNAi was constructed by the lentiviral expression system, pHelper1.0/pHelper2.0/pGCL2GFP. Bmi-1mRNA and protein expressions of stably transfected laryngeal carcinoma cells were identified tespectively by real-time PCR and Western blot analyses. The changes of the proliferation and invasiveness of laryngeal carcinoma were detected by clone formation test and an invasion assay. RESULT: The Bmi-1 mRNA expressions of stably transfected laryngeal carcinoma Hep-2 cells were significantly decreased. The expression of Bmi-1 protein in laryngeal carcinoma Hep-2 cells was significantly decreased. And the inhibitory rates were 79% and 88% respectively. Whereas the proliferation and invasiveness of Hep-2 cells were significantly reduced. CONCLUSION The Bmi-1 RNAi expression vector were constructed successful. Reduced Bmi-1 expression of Hep-2 cells demonstrated the role of Bmi-1 RNAi in restraining proliferation and invasiveness of laryngeal carcinoma cells.
Cell Line, Tumor ; Cell Proliferation ; genetics ; Genetic Vectors ; Humans ; Laryngeal Neoplasms ; genetics ; metabolism ; pathology ; Neoplasm Invasiveness ; genetics ; Polycomb Repressive Complex 1 ; metabolism ; RNA, Small Interfering ; metabolism ; Transfection

Objective To clarify whether Helicobacter pylori (H. pylori) can promote metastasis of gastric cancer cells via the high-expression of induced B cell specific Moloney murine leukemia virus integration site 1 (Bmi-1). Methods The gastric cancer tissue specimens from 82 patients were collected for this study. The protein and gene expression level of Bmi-1 in gastric adenocarcinoma tissue were detected by immunohistochemistry and real time quantitative PCR, respectively. And meanwhile the correlation between Bmi-1 levels and pathological features, and prognosis of gastric cancer were analyzed retrospectively. Then, the GES-1 cells were transfected with pLPCX-Bmi-1 plasmid and infected with H. pylori respectively. After the Bmi-1 overexpression in GES-1 cells, the invasion ability of the GES-1 cells was detected by Transwell assay, and the cell cycle and apoptosis were detected by flow cytometry. Results The mRNA and protein of Bmi-1 expression in gastric cancer tissues were higher than tumor-adjacent tissue, and the high expression of Bmi-1 was positively correlated with tumor invasion, TNM stage, tumor differentiation, lymph node metastasis and H. pylori infection. When expression of Bmi-1 was up-regulated as a result of H.pylori infection or pLPCX-Bmi-1 transfection, the GES-1 cells had higher invasiveness and lower apoptosis rate with the above treatment respectively. Conclusion H. pylori infection can inhibit the apoptosis of gastric cancer cells and promote their invasion via up-regulating expression of Bmi-1.
Humans ; Cell Line, Tumor ; Helicobacter Infections/genetics* ; Helicobacter pylori ; Lymphatic Metastasis ; Retrospective Studies ; Stomach Neoplasms/pathology* ; Polycomb Repressive Complex 1/genetics*

OBJECTIVETo determine the role of Bmi-1 in the submandibular gland (SMG) of mice.

METHODSSMG of 4-week wild-type (WT) and Bmi-1 null (Bmi-1(-/-)) mice was analyzed on the weight, salivary flow rate, hematoxylin-eosin staining morphological differences and the changes in proliferation and aging by histology, immunohistochemistry and Western blotting.

RESULTSCompared with WT mice, the average static salivary flow rate [WT:(0.21 ± 0.02) µg/min,Bmi-1(-/-): (0.10 ± 0.02) µg/min] (P = 0.001) and the submandibular gland weight [WT: (1.89 ± 0.15) µg], Bmi-1(-/-): [(1.34 ± 0.07)µg] (P = 0.003) of the male Bmi-1(-/-) mice were significantly decreased, the number of gland duct increased, and the granular convoluted duct showed reduced diameter and branches. More senescence-associated β-galactosidase positive cells existed in SMG of Bmi-1(-/-)mice (WT:0.00, Bmi-1(-/-): 0.18 ± 0.02), and Ki-67 immunopositive cells decreased in SMG of Bmi-1(-/-) mice (WT:0.40 ∼ 0.47, Bmi-1(-/-): 0.18 ∼ 0.20) (P = 0.000). The expression of p16 (WT:1.00 ± 0.12, Bmi-1(-/-): 0.00 ± 0.00) (P = 0.003) and p19 (WT:0.97 ± 0.09, Bmi-1(-/-): 5.09 ± 0.21) (P = 0.004) were up-regulated dramatically in SMG of the Bmi-1(-/-) mice.

CONCLUSIONSBmi-1 gene deficiency causes abnormal function of SMG by inducing senescence phenotype of SMG.

Animals ; Immunohistochemistry ; Male ; Mice ; Polycomb Repressive Complex 1 ; biosynthesis ; genetics ; Proto-Oncogene Proteins ; biosynthesis ; genetics ; Submandibular Gland ; growth & development ; metabolism ; Up-Regulation

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