Missense Mutations of the Pro65 Residue of PCGF2 Cause a Recognizable Syndrome Associated with Craniofacial, Neurological, Cardiovascular, and Skeletal Features.

PCGF2 encodes the polycomb group ring finger 2 protein, a transcriptional repressor involved in cell proliferation, differentiation, and embryogenesis. PCGF2 is a component of the polycomb repressive complex 1 (PRC1), a multiprotein complex which controls gene silencing through histone modification and chromatin remodelling. We report the phenotypic characterization of 13 patients (11 unrelated individuals and a pair of monozygotic twins) with missense mutations in PCGF2. All the mutations affected the same highly conserved proline in PCGF2 and were de novo, excepting maternal mosaicism in one. The patients demonstrated a recognizable facial gestalt, intellectual disability, feeding problems, impaired growth, and a range of brain, cardiovascular, and skeletal abnormalities. Computer structural modeling suggests the substitutions alter an N-terminal loop of PCGF2 critical for histone biding. Mutant PCGF2 may have dominant-negative effects, sequestering PRC1 components into complexes that lack the ability to interact efficiently with histones. These findings demonstrate the important role of PCGF2 in human development and confirm that heterozygous substitutions of the Pro65 residue of PCGF2 cause a recognizable syndrome characterized by distinctive craniofacial, neurological, cardiovascular, and skeletal features.

PARP1-dependent recruitment of the FBXL10-RNF68-RNF2 ubiquitin ligase to sites of DNA damage controls H2A.Z loading.

The mammalian FBXL10-RNF68-RNF2 ubiquitin ligase complex (FRRUC) mono-ubiquitylates H2A at Lys119 to repress transcription in unstressed cells. We found that the FRRUC is rapidly and transiently recruited to sites of DNA damage in a PARP1- and TIMELESS-dependent manner to promote mono-ubiquitylation of H2A at Lys119, a local decrease of H2A levels, and an increase of H2A.Z incorporation. Both the FRRUC and H2A.Z promote transcriptional repression, double strand break signaling, and homologous recombination repair (HRR). All these events require both the presence and activity of the FRRUC. Moreover, the FRRUC and its activity are required for the proper recruitment of BMI1-RNF2 and MEL18-RNF2, two other ubiquitin ligases that mono-ubiquitylate Lys119 in H2A upon genotoxic stress. Notably, whereas H2A.Z is not required for H2A mono-ubiquitylation, impairment of the latter results in the inhibition of H2A.Z incorporation. We propose that the recruitment of the FRRUC represents an early and critical regulatory step in HRR.

Inhibition of HSF2 SUMOylation via MEL18 upregulates IGF-IIR and leads to hypertension-induced cardiac hypertrophy.

Cardiac hypertrophy is a major characteristic of early-stage hypertension-related heart failure. We have found that the insulin-like growth factor receptor II (IGF-IIR) signaling was critical for hypertensive angiotensin II-induced cardiomyocyte hypertrophy and apoptosis. Moreover, this IGF-IIR signaling was elegantly modulated by the heat shock transcription factors (HSFs) during heart failure. However, the detailed mechanism by which HSFs regulates IGF-IIR during hypertension-induced cardiac hypertrophy remains elusive. In this study, we found that heat shock transcription factor 2 (HSF2) activated IGF-IIR to induce cardiac hypertrophy for hypertension-induced heart failure. The transcriptional activity of HSF2 appeared to be primarily mediated by SUMOylation via conjugation with small ubiquitin-like modifier-1 (SUMO-1). The SUMOylation of HSF2 was severely attenuated by MEL18 (also known as polycomb group ring finger 2 or PCGF2) in the heart of spontaneously hypertensive rats (SHR). Inhibition of HSF2 SUMOylation severely induced cardiac hypertrophy via IGF-IIR-mediated signaling in hypertensive rats. Angiotensin II receptor type I blocker (ARB) treatment in spontaneously hypertensive rats restored HSF2 SUMOylation and alleviated the cardiac defects. Thus, our study uncovered a novel MEL18-SUMO-1-HSF2-IGF-IIR pathway in the heart that profoundly influences cardiac hypertrophy for hypertension-induced heart failure.

Prognostic Significance of BMI-1 But Not MEL-18 Expression in Pulmonary Squamous Cell Carcinoma.

AIM: We investigated the possibility of BMI-1 and MEL-18 to predict survival in patients with pulmonary squamous cell carcinoma. MATERIALS AND METHODS: One hundred and ninety-nine patients underwent surgery in our Institute between 1995 and 2005. We used immunohistochemical (IHC) analysis to determine the expressions of BMI-1 and MEL-18 and compared them with clinicopathological factors and survival. RESULTS: Forty-one of 199 cases (21%) were BMI-1-positive. No correlation was found between BMI-1 and MEL-18 expression by IHC and clinicopathological factors. Five-year overall survival in the BMI-1-positive group (66.8%), but not MEL-18, was significantly better than that in the negative group (45.5%, p=0.04). In multivariate analysis, positive BMI-1 was a better prognostic factor of overall survival (hazard ratio (HR)=0.561, 95% confidence interval (CI)=0.271-1.16, p=0.12). CONCLUSION: BMI-1 expression, but not MEL-18, is associated with a favorable prognosis and is a possible prognostic factor of pulmonary squamous cell carcinoma.

Expression and Clinicopathological Significance of Mel-18 and Bmi-1 in Esophageal Squamous Cell Carcinoma.

The Polycomb group genes are a general class of regulators that are responsible for maintaining homeotic gene expression throughout cell division. Polycomb group expression plays an important role in oncogenesis of several types of human cancer. Melanoma nuclear protein 18 and B-cell-specific Moloney leukemia virus insert site 1 are key Polycomb group proteins. Studies have shown that melanoma nuclear protein 18 is a potential tumor suppression, and B-cell-specific Moloney leukemia virus insert site 1 is overexpressed in several human malignancies. However, the roles of melanoma nuclear protein 18 and B-cell-specific Moloney leukemia virus insert site 1 in esophageal squamous cell carcinoma are still unclear. In this study, we analyzed the expression levels of melanoma nuclear protein 18 and B-cell-specific Moloney leukemia virus insert site 1 in 89 esophageal cancer tissues and paired normal mucosal tissues using immunohistochemistry, Western blotting, and quantitative real-time polymerase chain reaction analyses. We found that the expression of melanoma nuclear protein 18 in the carcinoma tissues was significantly lower than that in the noncancerous mucosal tissues (P < .05), and B-cell-specific Moloney leukemia virus insert site 1 expression in the carcinoma tissues was significantly higher than that in the noncancerous mucosal tissues (P < .05). In addition, the expression of melanoma nuclear protein 18 was correlated with clinical stage, depth of invasion, and lymph node metastasis (P < .05) but was not correlated with gender, age, degree of differentiation, or disease-free survival (P > .05). B-cell-specific Moloney leukemia virus insert site 1 expression was strongly correlated with the degree of differentiation, clinical stage, and lymph node metastasis (P <.05) but was not correlated with the gender, age, depth of invasion or disease-free survival (P > .05). Moreover, there was a negative correlation between melanoma nuclear protein 18 and B-cell-specific Moloney leukemia virus insert site 1 expressions in esophageal squamous cell carcinoma (P < .05). Our study suggests that melanoma nuclear protein 18 and B-cell-specific Moloney leukemia virus insert site 1 may play a crucial role in esophageal squamous cell carcinoma. Melanoma nuclear protein 18 or B-cell-specific Moloney leukemia virus insert site 1 may be a potential biomarker for diagnosis and prognosis of esophageal squamous cell carcinoma.

Suppression of mel18 enhances differentiation of acute myeloid leukemia cell line HL60 induced by cinnamaldehyde / 中国病理生理杂志

AIM:To investigate the effect of suppression of mel18 gene on the differentiation of human acute myeloid leukemia cell line HL 60 induced by cinnamaldehyde ( CA) .METHODS:HL60 cells were treated with low con-centration of CA or all-trans retinoic acid (ATRA).shRNAmel18 vector and shRNALuc control vector were employed to package lentiviruses which were then used to infect HL 60 cells.The virus-infected HL60 cells were treated with low con-centration of CA , and ATRA was used as a positive control of differentiation-inducing agent .The differentiation markers on the cell surface and cell cycle of virus-infected HL60 cells were analyzed by flow cytometry .Western blot was used to deter-mine the expression of MEL18, cyclin D1 and p27, as well as the phosphorylation level of Akt .RESULTS:Low concen-tration of CA and ATRA increased the expression of granulocytic differentiation marker CD 11b on the HL60 cells, with the decreased expression of MEL 18 in the HL60 cells.The expression of MEL18 decreased in shmel18 virus-infected HL60 cells (shmel18-HL60 cells), but did not change in shLuc-HL60 cells.The expression of CD11b on shmel18-HL60 cells increased with G 1-phase arrest , which went even higher after treatment with CA .The phosphorylation level of Akt and the expression of cyclin D1 decreased in shmel18-HL60 cells with the increase in the expression of p27.CONCLUSION:In-hibition of mel18 gene leads HL60 cell granulocytic differentiation .mel18 gene may affect the differentiation of HL 60 cells by regulating cyclin D1 and p27 via PI3K/Akt signaling pathway.PI3K/Akt signaling pathway is also involved in CA-in-duced differentiation of HL60 cells by suppressing mel18 gene expression.

Suppression of mel18 enhances differentiation of acute myeloid leukemia cell line HL60 induced by cinnamaldehyde / 中国病理生理杂志

AIM:To investigate the effect of suppression of mel18 gene on the differentiation of human acute myeloid leukemia cell line HL 60 induced by cinnamaldehyde ( CA) .METHODS:HL60 cells were treated with low con-centration of CA or all-trans retinoic acid (ATRA).shRNAmel18 vector and shRNALuc control vector were employed to package lentiviruses which were then used to infect HL 60 cells.The virus-infected HL60 cells were treated with low con-centration of CA , and ATRA was used as a positive control of differentiation-inducing agent .The differentiation markers on the cell surface and cell cycle of virus-infected HL60 cells were analyzed by flow cytometry .Western blot was used to deter-mine the expression of MEL18, cyclin D1 and p27, as well as the phosphorylation level of Akt .RESULTS:Low concen-tration of CA and ATRA increased the expression of granulocytic differentiation marker CD 11b on the HL60 cells, with the decreased expression of MEL 18 in the HL60 cells.The expression of MEL18 decreased in shmel18 virus-infected HL60 cells (shmel18-HL60 cells), but did not change in shLuc-HL60 cells.The expression of CD11b on shmel18-HL60 cells increased with G 1-phase arrest , which went even higher after treatment with CA .The phosphorylation level of Akt and the expression of cyclin D1 decreased in shmel18-HL60 cells with the increase in the expression of p27.CONCLUSION:In-hibition of mel18 gene leads HL60 cell granulocytic differentiation .mel18 gene may affect the differentiation of HL 60 cells by regulating cyclin D1 and p27 via PI3K/Akt signaling pathway.PI3K/Akt signaling pathway is also involved in CA-in-duced differentiation of HL60 cells by suppressing mel18 gene expression.

Mel-18 negatively regulates stem cell-like properties through downregulation of miR-21 in gastric cancer.

Mel-18, a polycomb group protein, has been reported to act as a tumor suppressor and be down-regulated in several human cancers including gastric cancer. It was also found that Mel-18 negatively regulates self-renewal of hematopoietic stem cells and breast cancer stem cells (CSCs). This study aimed to clarify its role in gastric CSCs and explore the mechanisms. We found that low-expression of Mel-18 was correlated with poor prognosis and negatively correlated with overexpression of stem cell markers Oct4, Sox2, and Gli1 in 101 gastric cancer tissues. Mel-18 was down-regulated in cultured spheroid cells, which possess CSCs, and overexpression of Mel-18 inhibits cells sphere-forming ability and tumor growth in vivo. Besides, Mel-18 was lower-expressed in ovary metastatic lesions compared with that in primary lesions of gastric cancer, and Mel-18 overexpression inhibited the migration ability of gastric cancer cells. Interestingly, overexpression of Mel-18 resulted in down-regulation of miR-21 in gastric cancer cells and the expression of Mel-18 was negatively correlated with the expression of miR-21 in gastric cancer tissues. Furthermore, miR-21 overexpression partially restored sphere-forming ability, migration potential and chemo-resistance in Mel-18 overexpressing gastric cancer cells. These results suggests Mel-18 negatively regulates stem cell-like properties through downregulation of miR-21 in gastric cancer cells.

Mel-18 gene and neoplasms / 国际肿瘤学杂志

Mel-18 gene is one of the core members of the PcG (polycomb group) family,which plays an important role in embryogenesis,cell growth and proliferation and self-renewal of stem cells.Mel-18 gene expressing abnormally has been related to human tumorigenesis,development process.Mel-18 serves as a tumor suppressor gene and inhibits tumor growth through transcriptional repression of Bmi-1 and c-myc.Mel-18 expression is decreased at transcriptional and translational levels in most human cancers including breast cancer,prostate cancer,and gastric cancer and other tumors.Mel-18 is expected to become a prognostic marker for human cancers.

Expression and clinical significance of Mel-18 mRNA in gastric carcinoma / 中国癌症杂志

Background and purpose: Mel-18 is one of the mammalian polycomb group members. A number of related researches have implied that Mel-18 may play a role in human tumorigenesis.In this study, we measured the expression of Mel-18 in gastric carcinoma cells in vivo to explore the expression and clinical significance of Mel-18 in gastric carcinoma. Methods: Real time RT-PCR was used to detect the expression of Mel-18 in cancer tissue and corresponding normal tissue in 52 cases of gastric carcinoma. The association between Mel-18 expression and the clinicopathological parameters of the tumors was analyzed. Results: The analysis revealed that there was significantly decreased expression of Mel-18 in 18 (34.62%)carcinoma tissues in comparison with para-cancer normal tissue. There was no correlation between Mel-18 expression and clinicopathological parameters, such as age, gender, tumor size and histological differentiation (P>0.05).The decrease of Mel-18 expression was significantly negatively correlated with lymph node metastasis and clinical stage (P<0.05). The expression levels of Mel-18 evaluated by the ratios of gene expression were 1.357,0.453,0.183 and 0.170 in stage Ⅰ, Ⅱ,Ⅲ and Ⅳ gastric carcinoma, respectively. They were 0.634 and 0.210 in patients without lymph node metastasis and in patients with lymph node metastasis, respectively. Expression of Mel-18,lymph node metastasis, and clinical stage were significant covariates, respectively (P<0.05). Conclusion: Our results showed that Mel-18 might play a crucial role in tumorigenesis and progression of gastric carcinoma. It is possible that Mel-18 could be used as one of the biomarkers for predicting the prognosis of gastric carcinoma.

Expression and clinical signifi cance of Mel-18 mRNA in gastric carcinoma / 中国癌症杂志

0.05).The decrease of Mel-18 expression was signifi cantly negatively correlated with lymph node metastasis and clinical stage(P