Humans ; Models, Molecular ; Repressor Proteins ; chemistry ; metabolism ; Retinoblastoma-Binding Protein 4 ; chemistry ; metabolism

BACKGROUND: A long non-coding RNA hox transcript antisense intergenic RNA (HOTAIR) is involved in epigenetic regulation through chromatin remodeling by recruiting polycomb repressive complex 2 (PRC2) proteins (EZH2, SUZ12, and EED) that induce histone H3 trimethylation at lysine 27 (H3K27me3). Deregulation of c-MYC and interaction between c-MYC and EZH2 are well known in lymphomagenesis; however, little is known about the expression status of HOTAIR in diffuse large B-cell lymphomas (DLBCLs). METHODS: The expression status of PRC2 (EZH2, SUZ12, and EED), H3K27me3, c-MYC, and BCL2 was analyzed using immunohistochemistry (n = 231), and HOTAIR was investigated by a quantification real-time polymerase chain reaction method (n = 164) in DLBCLs. RESULTS: The present study confirmed the positive correlation among PRC2 proteins, H3K27me3, and c-MYC in DLBCLs. Expression level of HOTAIR was also positively correlated to EZH2 (p < .05, respectively). Between c-MYC and HOTAIR, and between c- MYC/BCL2 co-expression and HOTAIR, however, negative correlation was observed in DLBCLs (p < .05, respectively). High level of H3K27me3 was determined as an independent prognostic marker in poor overall survival (hazard ratio, 2.0; p = .023) of DLBCL patients. High expression of HOTAIR, however, was associated with favorable overall survival (p = .004) in the univariate analysis, but the impact was not significant in the multivariate analysis. The favorable outcome of DLBCL with HOTAIR high expression levels may be related to the negative correlation with c- MYC expression or c-MYC/BCL2 co-expression. CONCLUSIONS: HOTAIR expression could be one of possible mechanisms for inducing H3K27me3 via EZH2-related PRC2 activation, and induced H3K27me3 may be strongly related to aggressive DLBCLs which show poor patient outcome.
B-Lymphocytes* ; Chromatin Assembly and Disassembly ; Epigenomics ; Histones ; Humans ; Immunohistochemistry ; Lymphoma, B-Cell* ; Lymphoma, Large B-Cell, Diffuse ; Lysine ; Methods ; Multivariate Analysis ; Polycomb Repressive Complex 2 ; Real-Time Polymerase Chain Reaction ; RNA ; RNA, Long Noncoding*

PURPOSE: The enhancer of zeste homologue 2 (EZH2) is a catalytic subunit of the polycomb repressive complex 2, a highly conserved histone methyltransferase. EZH2 overexpression has been implicated in various malignancies, including breast cancer, where is associated with poor outcomes. This study aims to clarify nuclear EZH2 expression levels in breast cancers using immunohistochemistry (IHC) and correlate these findings with clinicopathologic variables, including prognostic significance. METHODS: IHC was performed on tissue microarrays of 432 invasive ductal carcinoma (IDC) tumors. Associations between EZH2 expression, clinicopathologic characteristics, and molecular subtype were retrospectively analyzed. The relationship between EZH2 protein expression in normal breast tissue and ductal carcinoma in situ (DCIS) was also assessed. RESULTS: High EZH2 expression was demonstrated in 215 of 432 tumors (49.8%). EZH2 was more frequently expressed in DCIS and IDC than in normal breast tissue (p=0.001). High EZH2 expression significantly correlated with high histologic grade (p<0.001), large tumor size (p=0.014), advanced pathologic stage (p=0.006), negative estrogen receptor status (p<0.001), positive human epidermal growth factor receptor 2 (HER2) status (p<0.001), high Ki-67 staining index (p<0.001), positive cytokeratin 5/6 status (p=0.003), positive epidermal growth factor receptor status (p<0.001), and positive p53 status (p<0.001). Based on molecular subtypes, high EZH2 expression was significantly associated with HER2-negative luminal B, HER2-positive luminal B, and HER2 type and triple-negative basal cancers (p<0.001). In patients with luminal A, there was a significant trend toward shorter overall survival for those with tumors having high EZH2 expression compared to those with tumors having low EZH2 expression (p=0.045). CONCLUSION: EZH2 is frequently upregulated in breast malignancies, and it may play an important role in cancer development and progression. Furthermore, EZH2 may be a prognostic marker, especially in patients with luminal A cancer.
Breast Neoplasms* ; Breast* ; Carcinoma, Ductal ; Carcinoma, Intraductal, Noninfiltrating ; Catalytic Domain ; Estrogens ; Histones ; Humans ; Immunohistochemistry ; Keratins ; Phenobarbital* ; Polycomb Repressive Complex 2 ; Prognosis ; Receptor, Epidermal Growth Factor ; Retrospective Studies

Bmi1 is a member of the polycomb group family of proteins, and it drives the carcinogenesis of various cancers and governs the self-renewal of multiple types of stem cells. However, its role in the initiation and progression of bladder cancer is not clearly known. The present study aimed to investigate the function of Bmi1 in the development of bladder cancer. Bmi1 expression was detected in human bladder cancer tissues and their adjacent normal tissues (n=10) by immunohistochemistry, qRT-PCR and Western blotting, respectively. Bmi1 small interference RNA (siRNA) was synthesized and transfected into human bladder carcinoma cells (EJ) by lipofectamine 2000. The Bmil expression at mRNA and protein levels was measured in EJ cells transfected with Bmil siRNA (0, 80, 160 nmol/L) by qRT-PCR and Western blotting, respectively. Cell viability and Ki67 expression (a marker of cell proliferation) were determined in Bmi1 siRNA-transfected cells by CCK-8 assay and qRT-PCR, respectively. Cell cycle of transfected cells was flow-cytometrically determined. Immunofluorescence and Western blotting were used to detect the expression levels of cell cycle-associated proteins cyclin D1 and cyclin E in the cells. Pro-apoptotic proteins Bax and caspase 3 and anti-apoptotic protein Bcl-2 were detected by Western blotting as well. Additionally, xenograft tumor models were established by inoculation of EJ cells (infected with Bmil shRNA/pLKO.1 lentivirus or not) into nude mice. The tumor volumes were measured every other day for 14 days. The results showed that the Bmil expression was significantly increased in bladder tumor tissues when compared with that in normal tissues (P<0.05). Perturbation of Bmi1 expression by using siRNA could significantly inhibit the proliferation of EJ cells (P<0.05). Bmi1 siRNA-transfected EJ cells were accumulated in G1 phase and the expression levels of cyclin D1 and cyclin E were down-regulated. Bax and caspase-3 expression levels were significantly increased and Bcl-2 levels decreased after Bmi1 knockdown. Tumor volume was conspicuously reduced in mice injected with EJ cells with Bmi1 knockdown. Our findings indicate that Bmi1 is a potential driver oncogene of bladder cancer and it may become a potential treatment target for human bladder cancer.
Animals ; Apoptosis ; genetics ; Carcinogenesis ; genetics ; metabolism ; pathology ; Carcinoma ; genetics ; metabolism ; pathology ; therapy ; Caspase 3 ; genetics ; metabolism ; Cell Line, Tumor ; Cyclin D1 ; antagonists & inhibitors ; genetics ; metabolism ; Cyclin E ; antagonists & inhibitors ; genetics ; metabolism ; G1 Phase Cell Cycle Checkpoints ; genetics ; Gene Expression Regulation, Neoplastic ; Humans ; Injections, Intralesional ; Ki-67 Antigen ; genetics ; metabolism ; Mice ; Mice, Nude ; Polycomb Repressive Complex 1 ; antagonists & inhibitors ; genetics ; metabolism ; Proto-Oncogene Proteins c-bcl-2 ; antagonists & inhibitors ; genetics ; metabolism ; RNA, Small Interfering ; administration & dosage ; genetics ; metabolism ; Signal Transduction ; Tumor Burden ; Urinary Bladder ; metabolism ; pathology ; Urinary Bladder Neoplasms ; genetics ; metabolism ; pathology ; therapy ; Xenograft Model Antitumor Assays ; bcl-2-Associated X Protein ; agonists ; genetics ; metabolism

OBJECTIVETo investigate the expression of enhancer of zeste homolog 2 (EZH2) in esophageal squamous cell carcinoma and its association with the prognosis of postoperative patients.

METHODSSurgical specimens were obtained from 102 patients with esophageal squamous cell carcinoma undergoing radical resection in our hospital from 1996 to 2006. Immunochemistry was employed to examine EZH2 protein expressions in the specimens, including 102 carcinoma tissue specimens, 30 adjacent tissue specimens and 30 normal esophageal tissue specimens. The expression levels of EZH2 were analyzed in relation to the clinicopathological parameters of the patients including gender, age, tumor differentiation, TNM, and lymph node metastasis. The postoperative patients were followed up to analyze the association of EZH2 expression with the clinical outcomes.

RESULTSThe esophageal squamous cell carcinoma tissue showed a higher EZH2 expression than the adjacent and normal esophageal tissues. EZH2 expression was higher in poorly differentiated carcinoma than in well differentiated tissue, and also higher in cases with lymph node metastasis than those without; the expression was higher in TNM stage II/III patients than in stage I patients but lower than in stage IV patients. The patients with low EZH2 expression was found to have a longer survival time than those with high EZH2 expression (P<0.05).

CONCLUSIONEZH2 plays an important role in the differentiation and metastasis of esophageal squamous cell carcinoma, and a high EZH2 expression is associated with a poor outcome in the the postoperative patients.

Carcinoma, Squamous Cell ; diagnosis ; metabolism ; Enhancer of Zeste Homolog 2 Protein ; Esophageal Neoplasms ; diagnosis ; metabolism ; Humans ; Lymphatic Metastasis ; Polycomb Repressive Complex 2 ; metabolism ; Postoperative Period ; Prognosis

OBJECTIVETo investigate the effect of RbAp48 knockdown on the migration and invasion of human cervical cancer cells and explore the mechanism.

METHODSA small interference RNA (siRNA) was used to knock down the expression of RbAp48 in MS751 cells. The changes in cell migration and invasion were evaluated using wound healing assay and Transwell assay, respectively, and the expressions of RbAp48, vimentin, N-cadherin, E-cadherin, Snail, Twist, MMP-2 and TIMP-2 were determined with Western blotting.

RESULTSAfter siRNA-mediated RbAp48 knockdown, MS751 cells showed a significantly reduced expression of RbAp48 with significantly suppressed cell migration and invasion (P<0.01). RbAp48 knockdown induced obvious down-regulation of the expressions of interstitial cell phenotype proteins vimentin, N-cadherin, and MMP-2 and up-regulation of epithelial cell phenotype proteins E-cadherin and TIMP-2, suggesting the inhibition of epithelial- mesenchymal transition of the cells. The expressions of Snail and Twist were significantly down-regulated in the cells following RbAp48 knockdown.

CONCLUSIONKnockdown of RbAp48 can significantly inhibit epithelial-mesenchymal transition and suppress the migration and invasion of cervical cancer cell line MS751, the mechanism of which may involve the down-regulation of Snail and Twist expressions.

Antigens, CD ; metabolism ; Cadherins ; metabolism ; Cell Line, Tumor ; Cell Movement ; Down-Regulation ; Epithelial-Mesenchymal Transition ; Female ; Gene Knockdown Techniques ; Humans ; Matrix Metalloproteinase 2 ; metabolism ; Neoplasm Invasiveness ; Nuclear Proteins ; metabolism ; RNA, Small Interfering ; Retinoblastoma-Binding Protein 4 ; genetics ; Snail Family Transcription Factors ; Tissue Inhibitor of Metalloproteinase-2 ; metabolism ; Transcription Factors ; metabolism ; Twist-Related Protein 1 ; metabolism ; Up-Regulation ; Uterine Cervical Neoplasms ; pathology ; Vimentin ; metabolism

OBJECTIVETo investigate the effect of miRNA-101 on the expression of the enhancer of zeste homolog 2 (EXH2) in human androgen-independent prostated cancer LNCaP cells.

METHODSWe divided LNCaP cells into a blank control, a negative control, and a miRNA-l01 transfection group, constructed the vector by transfecting synthetic miRNA-101 mimics into the LNCaP cells, and evaluated the efficiency of transfection by fluorescence microscopy. Then we determined the expression level of EZH2 mRNA by qRT-PCR in the three groups of cells and that of the EZH2 protein in the negative control and transfection groups by Western blot.

RESULTSGreen fluorescence signals were observed in over 70% of the LNCaP cells in the transfection group after 24 hours of transfection. At 72 hours, the expression of miRNA-101 was significantly upregulated in the transfected cells (P < 0.01), that of EZH2 mRNA was remarkably lower in the transfection group (0.01 ± 0.10) than in the blank control (0.95 ± 0.40) and negative control (0.86 ± 0.30) groups (both P < 0.01), and that of the EZH2 protein was increased in the negative control but decreased in the transfection group with the extension of culture time.

CONCLUSIONmiRNA-101, with its inhibitory effect on the expression of EZH2 in LNCaP cells, is a potential biotherapeutic for prostate cancer.

Androgens ; Cell Line, Tumor ; Enhancer of Zeste Homolog 2 Protein ; Genetic Vectors ; Humans ; Male ; MicroRNAs ; physiology ; Polycomb Repressive Complex 2 ; genetics ; metabolism ; Prostatic Neoplasms ; metabolism ; RNA, Messenger ; metabolism ; Transfection

Polycomb repressive complex 2 (PRC2) is the epigenetic regulator that induces histone H3 lysine 27 methylation (H3K27me3) and silences specific gene transcription. Enhancer of zeste homolog 2 (EZH2) is an enzymatic subunit of PRC2, and evidence shows that EZH2 plays an essential role in cancer initiation, development, progression, metastasis, and drug resistance. EZH2 expression is indeed regulated by various oncogenic transcription factors, tumor suppressor miRNAs, and cancer-associated non-coding RNA. EZH2 activity is also controlled by post-translational modifications, which are deregulated in cancer. The canonical role of EZH2 is gene silencing through H3K27me3, but accumulating evidence shows that EZH2 methlyates substrates other than histone and has methylase-independent functions. These non-canonical functions of EZH2 are shown to play a role in cancer progression. In this review, we summarize current information on the regulation and roles of EZH2 in cancer. We also discuss various therapeutic approaches to targeting EZH2.
Drug Resistance ; Epigenomics ; Gene Silencing ; Histones ; Lysine ; Methylation ; MicroRNAs ; Neoplasm Metastasis ; Polycomb Repressive Complex 2 ; Protein Processing, Post-Translational ; RNA, Untranslated ; Transcription Factors ; Transcription, Genetic

Antineoplastic Agents ; therapeutic use ; Enhancer of Zeste Homolog 2 Protein ; Epigenesis, Genetic ; Histone Deacetylase Inhibitors ; therapeutic use ; Humans ; Hydroxamic Acids ; therapeutic use ; Indoles ; therapeutic use ; Lymphoma ; classification ; drug therapy ; genetics ; metabolism ; MicroRNAs ; metabolism ; Phenotype ; Polycomb Repressive Complex 2 ; metabolism ; Polycomb-Group Proteins ; metabolism

OBJECTIVETo screen novel miRNAs targeting EZH2 3' untranslated region (UTR) in recombinational MCF-7 breast cancer cells over-expressing EZH2 3' UTR and quantitative analyze the expressions of the screened miRNA in breast cancer cells and tissues.

METHODSA lentiviral library was transfected into the recombinant cell line MCF-7. The cells were screened with cytotoxic agents before extraction of the genome for amplification of the miRNA precursors using PCR. The screened miRNAs were identified with sequence analysis and their expressions were analyzed quantitatively with real-time PCR in breast cancer cells and tissues.

RESULTSSeven miRNAs were screened from the recombinant MCF-7 cells, namely miR-15b, miR-16-2, miR-181b2, miR-217, miR-224, miR-329-1, and miR-487b, all of which failed to be predicted by bioinformatics software. Real-time PCR showed that miR-217, miR-329-1, and miR-487b were over-expressed in MCF-7 cells, and the expression of miR-15b and miR-16-2 was significantly increased in cancer tissues compared with the adjacent tissues (P<0.05).

CONCLUSIONNovel targeted miRNAs that can not be predicted by bioinformatics software were successfully screened from MCF-7 breast cancer cells over-expressing EZH2 3' UTR. These miRNAs are expressed differentially between normal breast cells and breast cancer tissues.

3' Untranslated Regions ; Breast Neoplasms ; genetics ; Cell Line, Tumor ; Enhancer of Zeste Homolog 2 Protein ; Female ; Gene Expression Profiling ; Humans ; Lentivirus ; genetics ; MicroRNAs ; genetics ; Polycomb Repressive Complex 2 ; genetics