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Anne Klibanski - One of the best experts on this subject based on the ideXlab platform.
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The long non-coding RNA MEG3 is dispensable for hematopoietic stem cells
Scientific reports, 2019Co-Authors: Pia Sommerkamp, Yunli Zhou, Simon Renders, Luisa Ladel, Agnes Hotz-wagenblatt, Katharina Schönberger, Petra Zeisberger, Adriana Przybylla, Markus Sohn, Anne KlibanskiAbstract:The long non-coding RNA (lncRNA) Maternally Expressed Gene 3 (MEG3) is encoded within the imprinted Dlk1-MEG3 gene locus and is only maternally expressed. MEG3 has been shown to play an important role in the regulation of cellular proliferation and functions as a tumor suppressor in numerous tissues. MEG3 is highly expressed in mouse adult hematopoietic stem cells (HSCs) and strongly down-regulated in early progenitors. To address its functional role in HSCs, we used MxCre to conditionally delete MEG3 in the adult bone marrow of MEG3mat-flox/pat-wt mice. We performed extensive in vitro and in vivo analyses of mice carrying a MEG3 deficient blood system, but neither observed impaired hematopoiesis during homeostatic conditions nor upon serial transplantation. Furthermore, we analyzed VavCre MEG3mat-flox/pat-wt mice, in which MEG3 was deleted in the embryonic hematopoietic system and unexpectedly this did neither generate any hematopoietic defects. In response to interferon-mediated stimulation, MEG3 deficient adult HSCs responded highly similar compared to controls. Taken together, we report the finding, that the highly expressed imprinted lncRNA MEG3 is dispensable for the function of HSCs during homeostasis and in response to stress mediators as well as for serial reconstitution of the blood system in vivo.
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tumor suppression by MEG3 lncrna in a human pituitary tumor derived cell line
Molecular and Cellular Endocrinology, 2015Co-Authors: Paweena Chunharojrith, Yuki Nakayama, Xiaobing Jiang, Rachel E Kery, Cristine S De La Hoz Ulloa, Xun Zhang, Yunli Zhou, Anne KlibanskiAbstract:Human clinically non-functioning pituitary adenomas (NFAs) account for approximately 40% of diagnosed pituitary tumors. Epigenetic mutations in tumor suppressive genes play an important role in NFA development. Maternally expressed gene 3 (MEG3) is a long non-coding RNA (lncRNA) and we hypothesized that it is a candidate tumor suppressor whose epigenetic silencing is specifically linked to NFA development. In this study, we introduced MEG3 expression into PDFS cells, derived from a human NFA, using both inducible and constitutively active expression systems. MEG3 expression significantly suppressed xenograft tumor growth in vivo in nude mice. When induced in culture, MEG3 caused cell cycle arrest at the G1 phase. In addition, inactivation of p53 completely abolished tumor suppression by MEG3, indicating that MEG3 tumor suppression is mediated by p53. In conclusion, our data support the hypothesis that MEG3 is a lncRNA tumor suppressor in the pituitary and its inactivation contributes to NFA development.
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MEG3 noncoding RNA: a tumor suppressor
Journal of molecular endocrinology, 2012Co-Authors: Yunli Zhou, Xun Zhang, Anne KlibanskiAbstract:Maternally expressed gene 3 (MEG3) is an imprinted gene belonging to the imprinted DLK1-MEG3 locus located at chromosome 14q32.3 in humans. Its mouse ortholog, MEG3, also known as gene trap locus 2 (Gtl2), is located at distal chromosome 12. The MEG3 gene encodes a long noncoding RNA (lncRNA) and is expressed in many normal tissues. MEG3 gene expression is lost in an expanding list of primary human tumors and tumor cell lines. Multiple mechanisms contribute to the loss of MEG3 expression in tumors, including gene deletion, promoter hypermethylation, and hypermethylation of the intergenic differentially methylated region. Re-expression of MEG3 inhibits tumor cell proliferation in culture and colony formation in soft agar. This growth inhibition is partly the result of apoptosis induced by MEG3. MEG3 induces accumulation of p53 (TP53) protein, stimulates transcription from a p53-dependent promoter, and selectively regulates p53 target gene expression. Maternal deletion of the MEG3 gene in mice results in skeletal muscle defects and perinatal death. Inactivation of MEG3 leads to a significant increase in expression of angiogenesis-promoting genes and microvessel formation in the brain. These lines of evidence strongly suggest that MEG3 functions as a novel lncRNA tumor suppressor.
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selective loss of MEG3 expression and intergenic differentially methylated region hypermethylation in the MEG3 dlk1 locus in human clinically nonfunctioning pituitary adenomas
The Journal of Clinical Endocrinology and Metabolism, 2008Co-Authors: Roger Gejman, Xun Zhang, Yunli Zhou, Ying Zhong, Dalia L. Batista, Brooke Swearingen, Constantine A. Stratakis, Tessa E Hedleywhyte, Anne KlibanskiAbstract:Context: MEG3 is an imprinted gene encoding a novel noncoding RNA that suppresses tumor cell growth. Although highly expressed in the normal human pituitary, it is unknown which of the normal pituitary cell types and pituitary tumors express MEG3. Objectives: Our objectives were 1) to investigate cell-type- and tumor-type-specific expression of MEG3 in the human pituitary and 2) to investigate whether methylation in the intergenic differentially methylated region (IG-DMR) at the DLK1/MEG3 locus is involved in the loss of MEG3 expression in tumors. Design and Methods: RT-PCR, quantitative RT-PCR, Northern blot, and a combination of in situ hybridization and immunofluorescence were used to determine the cell-type- and tumor-type-specific MEG3 expression. Bisulfite treatment and PCR sequencing of genomic DNA were used to measure the CpG methylation status in the normal and tumor tissues. Five normal human pituitaries and 17 clinically nonfunctioning, 11 GH-secreting, seven prolactin-secreting, and six ACTH-secreting pituitary adenomas were used. Results: All normal human pituitary cell types express MEG3. However, loss of MEG3 expression occurs only in nonfunctioning pituitary adenomas of a gonadotroph origin. All other pituitary tumor phenotypes examined express MEG3. Hypermethylation of the IG-DMR at the DLK1/MEG3 locus is present in nonfunctioning pituitary adenomas. Conclusions: MEG3 is the first human gene identified expressed in multiple normal human pituitary cell types with loss of expression specifically restricted to clinically nonfunctioning pituitary adenomas. The IG-DMR hypermethylation may be an additional mechanism for MEG3 gene silencing in such tumors.
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Selective loss of MEG3 expression and intergenic differentially methylated region hypermethylation in the MEG3/DLK1 locus in human clinically nonfunctioning pituitary adenomas.
The Journal of clinical endocrinology and metabolism, 2008Co-Authors: Roger Gejman, Xun Zhang, Yunli Zhou, Ying Zhong, Dalia L. Batista, Brooke Swearingen, Constantine A. Stratakis, E. Tessa Hedley-whyte, Anne KlibanskiAbstract:MEG3 is an imprinted gene encoding a novel noncoding RNA that suppresses tumor cell growth. Although highly expressed in the normal human pituitary, it is unknown which of the normal pituitary cell types and pituitary tumors express MEG3. Our objectives were 1) to investigate cell-type- and tumor-type-specific expression of MEG3 in the human pituitary and 2) to investigate whether methylation in the intergenic differentially methylated region (IG-DMR) at the DLK1/MEG3 locus is involved in the loss of MEG3 expression in tumors. RT-PCR, quantitative RT-PCR, Northern blot, and a combination of in situ hybridization and immunofluorescence were used to determine the cell-type- and tumor-type-specific MEG3 expression. Bisulfite treatment and PCR sequencing of genomic DNA were used to measure the CpG methylation status in the normal and tumor tissues. Five normal human pituitaries and 17 clinically nonfunctioning, 11 GH-secreting, seven prolactin-secreting, and six ACTH-secreting pituitary adenomas were used. All normal human pituitary cell types express MEG3. However, loss of MEG3 expression occurs only in nonfunctioning pituitary adenomas of a gonadotroph origin. All other pituitary tumor phenotypes examined express MEG3. Hypermethylation of the IG-DMR at the DLK1/MEG3 locus is present in nonfunctioning pituitary adenomas. MEG3 is the first human gene identified expressed in multiple normal human pituitary cell types with loss of expression specifically restricted to clinically nonfunctioning pituitary adenomas. The IG-DMR hypermethylation may be an additional mechanism for MEG3 gene silencing in such tumors.
Yunli Zhou - One of the best experts on this subject based on the ideXlab platform.
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The long non-coding RNA MEG3 is dispensable for hematopoietic stem cells
Scientific reports, 2019Co-Authors: Pia Sommerkamp, Yunli Zhou, Simon Renders, Luisa Ladel, Agnes Hotz-wagenblatt, Katharina Schönberger, Petra Zeisberger, Adriana Przybylla, Markus Sohn, Anne KlibanskiAbstract:The long non-coding RNA (lncRNA) Maternally Expressed Gene 3 (MEG3) is encoded within the imprinted Dlk1-MEG3 gene locus and is only maternally expressed. MEG3 has been shown to play an important role in the regulation of cellular proliferation and functions as a tumor suppressor in numerous tissues. MEG3 is highly expressed in mouse adult hematopoietic stem cells (HSCs) and strongly down-regulated in early progenitors. To address its functional role in HSCs, we used MxCre to conditionally delete MEG3 in the adult bone marrow of MEG3mat-flox/pat-wt mice. We performed extensive in vitro and in vivo analyses of mice carrying a MEG3 deficient blood system, but neither observed impaired hematopoiesis during homeostatic conditions nor upon serial transplantation. Furthermore, we analyzed VavCre MEG3mat-flox/pat-wt mice, in which MEG3 was deleted in the embryonic hematopoietic system and unexpectedly this did neither generate any hematopoietic defects. In response to interferon-mediated stimulation, MEG3 deficient adult HSCs responded highly similar compared to controls. Taken together, we report the finding, that the highly expressed imprinted lncRNA MEG3 is dispensable for the function of HSCs during homeostasis and in response to stress mediators as well as for serial reconstitution of the blood system in vivo.
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tumor suppression by MEG3 lncrna in a human pituitary tumor derived cell line
Molecular and Cellular Endocrinology, 2015Co-Authors: Paweena Chunharojrith, Yuki Nakayama, Xiaobing Jiang, Rachel E Kery, Cristine S De La Hoz Ulloa, Xun Zhang, Yunli Zhou, Anne KlibanskiAbstract:Human clinically non-functioning pituitary adenomas (NFAs) account for approximately 40% of diagnosed pituitary tumors. Epigenetic mutations in tumor suppressive genes play an important role in NFA development. Maternally expressed gene 3 (MEG3) is a long non-coding RNA (lncRNA) and we hypothesized that it is a candidate tumor suppressor whose epigenetic silencing is specifically linked to NFA development. In this study, we introduced MEG3 expression into PDFS cells, derived from a human NFA, using both inducible and constitutively active expression systems. MEG3 expression significantly suppressed xenograft tumor growth in vivo in nude mice. When induced in culture, MEG3 caused cell cycle arrest at the G1 phase. In addition, inactivation of p53 completely abolished tumor suppression by MEG3, indicating that MEG3 tumor suppression is mediated by p53. In conclusion, our data support the hypothesis that MEG3 is a lncRNA tumor suppressor in the pituitary and its inactivation contributes to NFA development.
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MEG3 noncoding RNA: a tumor suppressor
Journal of molecular endocrinology, 2012Co-Authors: Yunli Zhou, Xun Zhang, Anne KlibanskiAbstract:Maternally expressed gene 3 (MEG3) is an imprinted gene belonging to the imprinted DLK1-MEG3 locus located at chromosome 14q32.3 in humans. Its mouse ortholog, MEG3, also known as gene trap locus 2 (Gtl2), is located at distal chromosome 12. The MEG3 gene encodes a long noncoding RNA (lncRNA) and is expressed in many normal tissues. MEG3 gene expression is lost in an expanding list of primary human tumors and tumor cell lines. Multiple mechanisms contribute to the loss of MEG3 expression in tumors, including gene deletion, promoter hypermethylation, and hypermethylation of the intergenic differentially methylated region. Re-expression of MEG3 inhibits tumor cell proliferation in culture and colony formation in soft agar. This growth inhibition is partly the result of apoptosis induced by MEG3. MEG3 induces accumulation of p53 (TP53) protein, stimulates transcription from a p53-dependent promoter, and selectively regulates p53 target gene expression. Maternal deletion of the MEG3 gene in mice results in skeletal muscle defects and perinatal death. Inactivation of MEG3 leads to a significant increase in expression of angiogenesis-promoting genes and microvessel formation in the brain. These lines of evidence strongly suggest that MEG3 functions as a novel lncRNA tumor suppressor.
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selective loss of MEG3 expression and intergenic differentially methylated region hypermethylation in the MEG3 dlk1 locus in human clinically nonfunctioning pituitary adenomas
The Journal of Clinical Endocrinology and Metabolism, 2008Co-Authors: Roger Gejman, Xun Zhang, Yunli Zhou, Ying Zhong, Dalia L. Batista, Brooke Swearingen, Constantine A. Stratakis, Tessa E Hedleywhyte, Anne KlibanskiAbstract:Context: MEG3 is an imprinted gene encoding a novel noncoding RNA that suppresses tumor cell growth. Although highly expressed in the normal human pituitary, it is unknown which of the normal pituitary cell types and pituitary tumors express MEG3. Objectives: Our objectives were 1) to investigate cell-type- and tumor-type-specific expression of MEG3 in the human pituitary and 2) to investigate whether methylation in the intergenic differentially methylated region (IG-DMR) at the DLK1/MEG3 locus is involved in the loss of MEG3 expression in tumors. Design and Methods: RT-PCR, quantitative RT-PCR, Northern blot, and a combination of in situ hybridization and immunofluorescence were used to determine the cell-type- and tumor-type-specific MEG3 expression. Bisulfite treatment and PCR sequencing of genomic DNA were used to measure the CpG methylation status in the normal and tumor tissues. Five normal human pituitaries and 17 clinically nonfunctioning, 11 GH-secreting, seven prolactin-secreting, and six ACTH-secreting pituitary adenomas were used. Results: All normal human pituitary cell types express MEG3. However, loss of MEG3 expression occurs only in nonfunctioning pituitary adenomas of a gonadotroph origin. All other pituitary tumor phenotypes examined express MEG3. Hypermethylation of the IG-DMR at the DLK1/MEG3 locus is present in nonfunctioning pituitary adenomas. Conclusions: MEG3 is the first human gene identified expressed in multiple normal human pituitary cell types with loss of expression specifically restricted to clinically nonfunctioning pituitary adenomas. The IG-DMR hypermethylation may be an additional mechanism for MEG3 gene silencing in such tumors.
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Selective loss of MEG3 expression and intergenic differentially methylated region hypermethylation in the MEG3/DLK1 locus in human clinically nonfunctioning pituitary adenomas.
The Journal of clinical endocrinology and metabolism, 2008Co-Authors: Roger Gejman, Xun Zhang, Yunli Zhou, Ying Zhong, Dalia L. Batista, Brooke Swearingen, Constantine A. Stratakis, E. Tessa Hedley-whyte, Anne KlibanskiAbstract:MEG3 is an imprinted gene encoding a novel noncoding RNA that suppresses tumor cell growth. Although highly expressed in the normal human pituitary, it is unknown which of the normal pituitary cell types and pituitary tumors express MEG3. Our objectives were 1) to investigate cell-type- and tumor-type-specific expression of MEG3 in the human pituitary and 2) to investigate whether methylation in the intergenic differentially methylated region (IG-DMR) at the DLK1/MEG3 locus is involved in the loss of MEG3 expression in tumors. RT-PCR, quantitative RT-PCR, Northern blot, and a combination of in situ hybridization and immunofluorescence were used to determine the cell-type- and tumor-type-specific MEG3 expression. Bisulfite treatment and PCR sequencing of genomic DNA were used to measure the CpG methylation status in the normal and tumor tissues. Five normal human pituitaries and 17 clinically nonfunctioning, 11 GH-secreting, seven prolactin-secreting, and six ACTH-secreting pituitary adenomas were used. All normal human pituitary cell types express MEG3. However, loss of MEG3 expression occurs only in nonfunctioning pituitary adenomas of a gonadotroph origin. All other pituitary tumor phenotypes examined express MEG3. Hypermethylation of the IG-DMR at the DLK1/MEG3 locus is present in nonfunctioning pituitary adenomas. MEG3 is the first human gene identified expressed in multiple normal human pituitary cell types with loss of expression specifically restricted to clinically nonfunctioning pituitary adenomas. The IG-DMR hypermethylation may be an additional mechanism for MEG3 gene silencing in such tumors.
Yali Gao - One of the best experts on this subject based on the ideXlab platform.
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DNMT1 protein promotes retinoblastoma proliferation by silencing MEG3 gene
Nan fang yi ke da xue xue bao = Journal of Southern Medical University, 2020Co-Authors: Yali Gao, Xiaoling Luo, Ting Meng, Minjuan Zhu, Meiwen TianAbstract:To investigate whether DNMT1 protein induces retinoblastoma proliferation by silencing MEG3 gene. Two retinoblastoma cell lines (HXO-RB44 and SO-RB50) and a normal human retinal pigment epithelial (RPE) cell line were transfected with the plasmid pcDNA-DNMT1 or si-DNMT1 for up-regulating or interference of DNMT1 expression, and with pcDNA-MEG3 or si-MEG3 for up-regulating or interference of MEG3 expression. Western blotting was used to detect the changes in the expression of DNMT1 protein in the transfected cells, and CCK-8 and EdU assays were used to detect the changes in cell proliferation. Real-time quantitative PCR (qRT-PCR) was performed to detect MEG3 expression in SO-RB50 and HXO-RB44 cells after transfection, and the methylation level of MEG3 gene promoter after interference of DNMT1 expression was detected using methylation-specific PCR. SO-RB50 and HXO-RB44 cells showed significantly increased expression of DNMT1 protein as compared with normal RPE cells (P < 0.05). In HXO-RB44 cells, transfection with pcDNADNMT1 resulted in significantly increased expression of DNMT1 protein, enhanced cell proliferation ability, and significantly reduced expression of MEG3 (P < 0.05). In SO-RB50 cells, transfection with si-DNMT1 significantly reduced the expression of DNMT1 protein, suppressed the cell proliferation, and increased MEG3 expression (P < 0.05). Interference of DNMT1 significantly reduced the methylation level of MEG3 gene promoter. After reversing the regulatory effect of DNMT1 on MEG3 gene, DNMT1 protein showed significantly weakened ability to regulate retinoblastoma cell proliferation (P < 0.05). In retinoblastoma cells, the up-regulation of DNMT1 protein induces promoter methylation and inactivation of MEG3 gene and eventually leads to abnormal cell proliferation.
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Hypermethylation of MEG3 promoter correlates with inactivation of MEG3 and poor prognosis in patients with retinoblastoma
Journal of translational medicine, 2017Co-Authors: Yali Gao, Peng Huang, Jun ZhangAbstract:In our previous study, we revealed that MEG3 was a tumor suppressor gene in retinoblastoma and inhibited proliferation of retinoblastoma cells by regulating the activity of the Wnt/β-catenin pathway. Here, we further explored the mechanism of MEG3 inactivation in retinoblastoma. MSP and qRT-PCR were performed to detect the methylation status of MEG3 promoter and levels of MEG3 expression, respective. To further explore relationship between MEG3 expression and epigenetic modifications, 5-Aza-CdR was used to interfere with DNA methylation. In addition, we evaluated proliferation, apoptosis and the expression of β-catenin via CCK-8, flow cytometric analysis and western blot analysis, respective. Hypermethylation of MEG3 promoter was observed more frequently in retinoblastoma tissues and was highly associated with low MEG3 expression and poor survival of retinoblastoma patients. We also provided evidence demonstrating that hypermethylation of MEG3 promoter depressed MEG3 expression, promoted proliferation, inhibited apoptosis and increased β-catenin expression of retinoblastoma cells in vitro. Our present study indicates that promoter silencing by hypermethylation may account for the loss of MEG3 expression and predict poor prognosis.
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Aberrant Methylation of MEG3 Functions as a Potential Plasma-Based Biomarker for Cervical Cancer
Scientific reports, 2017Co-Authors: Jun Zhang, Zhongqiu Lin, Tingting Yao, Yali GaoAbstract:Methylation alterations of specific genes have recently been identified as diagnostic biomarkers for human cancers. Although MEG3 has been proved to be a tumor suppressor in cervical cancer according to our previous study, the diagnostic value of MEG3 methylation in plasma is still unknown. Therefore, the aim of this study is to identify a novel epigenetic biomarker for cervical cancer. In the current study, the level of MEG3 methylation was evaluated using methylation-specific polymerase chain reaction. The results showed that the level of MEG3 methylation was significantly higher in cervical cancer tissues and patients’ plasmas than those in adjacent normal tissues and plasmas of healthy participants respectively. Moreover, the accuracy was good enough for MEG3 methylation in plasma to discriminate CIN III patients from healthy participants. In addition, MEG3 methylation in plasma also has high discriminating power to predict HR-HPV infection and lymph node metastasis. Furthermore, hypermethylation of MEG3 in plasma was associated with worse recurrence-free and overall survival in cervical cancer patients. In conclusions, MEG3 methylation in plasma can serve as a diagnostic and prognostic biomarker for cervical cancer, providing useful information for clinical management.
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downregulation of long noncoding rna MEG3 is associated with poor prognosis and promoter hypermethylation in cervical cancer
Journal of Experimental & Clinical Cancer Research, 2017Co-Authors: Yali Gao, Jun Zhang, Zhongqiu Lin, Tingting YaoAbstract:Our previous study reported that MEG3 is an important tumor suppressor gene that is inactivated in cervical cancer. However, the diagnostic and prognostic values of MEG3, as well as the molecular mechanism of MEG3 inactivation in cervical cancer, remain unclear. In this study, we aimed to further elucidate the role and potential inactivation mechanism of MEG3 in cervical cancer. ROC curve and Cox regression analyses were used to assess the diagnostic and prognostic value of MEG3 in patients with cervical cancer. The methylation status of the MEG3 promoter in cervical cancer tissue samples was tested using methylation-specific PCR. Furthermore, we altered the methylation status of the MEG3 promoter in two cervical cancer cell lines (HeLa and CaSki) using a DNA methylation transfer enzyme inhibitor (5-Aza-CdR), to investigate whether promoter hypermethylation is a potential cause of MEG3 inactivation. Finally, we used CCK-8 and colony formation assays to evaluate the cell proliferation ability of HeLa and CaSki cells that had been treated with 5-aza-CdR, to investigate whether downregulation of MEG3 caused by promoter hypermethylation had biological effects. ROC curve analysis indicated that MEG3 status showed sufficient sensitivity and specificity for prediction of tumor size and lymph node metastasis in patients with cervical cancer. In addition, our follow-up data showed that low MEG3 expression was correlated with recurrence and short overall survival. Moreover, hypermethylation of the MEG3 promoter was observed in most cervical cancer tissue samples, and demethylation of the MEG3 promoter led to re-expression of MEG3 and inhibited proliferation of HeLa and CaSki cells. MEG3 is a powerful tool for diagnosis and prognosis of patients with cervical cancer, and low expression of MEG3 is likely to be related to promoter hypermethylation in cervical cancer.
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decreased expression of MEG3 contributes to retinoblastoma progression and affects retinoblastoma cell growth by regulating the activity of wnt β catenin pathway
Tumor Biology, 2016Co-Authors: Yali GaoAbstract:The aberrant expression of MEG3 has been found in some types of cancers; however, little is known concerning the function of MEG3 in retinoblastoma. To elucidate the roles of MEG3 in retinoblastoma, MEG3 expression was quantified in 63 retinoblastoma samples and corresponding nontumor tissues in this work. Moreover, retinoblastoma cell lines were transfected with pcDNA3.1-MEG3 or si-MEG3, after which proliferation, apoptosis, and expression of β-catenin were assayed. TOP-Flash reporter assay was also used to investigate the activity of the Wnt/β-catenin pathway. The results showed that MEG3 was downregulated in retinoblastoma tissues, and the level of MEG3 was negatively associated with IIRC stages and nodal or distant metastasis. More importantly, Kaplan-Meier survival analysis demonstrated that patients with low MEG3 expression had poorer survival and multivariate Cox regression analysis revealed that MEG3 was an independent prognostic factor in retinoblastoma patients. We also observed that MEG3 expression can be modulated by DNA methylation by using 5-aza-CdR treatment. In addition, overexpression of MEG3 suppressed proliferation, promoted apoptosis, and influences the activity of the Wnt/β-catenin pathway in retinoblastoma cell lines. Furthermore, we found that Wnt/β-catenin pathway activator rescued the anticancer effect of MEG3 in retinoblastoma. In conclusion, our study for the first time demonstrated that MEG3 was a tumor suppressor by negatively regulating the activity of the Wnt/β-catenin pathway in the progression of retinoblastoma and might serve as a prognostic biomarker and molecular therapeutic target.
Xun Zhang - One of the best experts on this subject based on the ideXlab platform.
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MEG3-DMR, not the MEG3 gene, regulates imprinting of the Dlk1-Dio3 locus
Developmental biology, 2019Co-Authors: Wende Zhu, Xun Zhang, Erin M. Botticelli, Rachel Kery, Yanfei Mao, Xin Wang, Anli Yang, Xianling Wang, Jie Zhou, Roy J. SobermanAbstract:Abstract The imprinted delta like 1 homolog (DLK1) - thyroxine deiodinase type III (DIO3) locus regulates development and growth. Its imprinting regulation involves two differentially methylated regions (DMRs), intergenic-DMR (IG-DMR) and maternally expressed gene 3-DMR (MEG3-DMR). In mice, a maternal deletion of the IG-DMR leads to LOI in the locus, proving that the IG-DMR is a cis-acting imprinting control region of the locus. However, the MEG3-DMR overlaps with the promoter, exon 1 and intron 1 of the MEG3 gene. Because deletion of the MEG3-DMR inactivates the MEG3 gene, their roles in imprinting regulation of MEG3-DMR mice is unknown. Therefore, we generated two mouse models: MEG3Δ(1-4) and MEG3Δ(2-4), respectively targeting exons 1–4 and exons 2–4 of the MEG3 gene. A maternal deletion of MEG3Δ(1-4) caused embryonic death and LOI in both embryos and placentas, but did not affect methylation status of the IG-DMR. In contrast, mice carrying a maternal deletion of MEG3Δ(2-4) were born normally and did not have LOI. These data indicate that it is the MEG3-DMR, not the MEG3 gene, which regulates imprinting of the Dlk1-Dio3 locus.
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tumor suppression by MEG3 lncrna in a human pituitary tumor derived cell line
Molecular and Cellular Endocrinology, 2015Co-Authors: Paweena Chunharojrith, Yuki Nakayama, Xiaobing Jiang, Rachel E Kery, Cristine S De La Hoz Ulloa, Xun Zhang, Yunli Zhou, Anne KlibanskiAbstract:Human clinically non-functioning pituitary adenomas (NFAs) account for approximately 40% of diagnosed pituitary tumors. Epigenetic mutations in tumor suppressive genes play an important role in NFA development. Maternally expressed gene 3 (MEG3) is a long non-coding RNA (lncRNA) and we hypothesized that it is a candidate tumor suppressor whose epigenetic silencing is specifically linked to NFA development. In this study, we introduced MEG3 expression into PDFS cells, derived from a human NFA, using both inducible and constitutively active expression systems. MEG3 expression significantly suppressed xenograft tumor growth in vivo in nude mice. When induced in culture, MEG3 caused cell cycle arrest at the G1 phase. In addition, inactivation of p53 completely abolished tumor suppression by MEG3, indicating that MEG3 tumor suppression is mediated by p53. In conclusion, our data support the hypothesis that MEG3 is a lncRNA tumor suppressor in the pituitary and its inactivation contributes to NFA development.
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MEG3 noncoding RNA: a tumor suppressor
Journal of molecular endocrinology, 2012Co-Authors: Yunli Zhou, Xun Zhang, Anne KlibanskiAbstract:Maternally expressed gene 3 (MEG3) is an imprinted gene belonging to the imprinted DLK1-MEG3 locus located at chromosome 14q32.3 in humans. Its mouse ortholog, MEG3, also known as gene trap locus 2 (Gtl2), is located at distal chromosome 12. The MEG3 gene encodes a long noncoding RNA (lncRNA) and is expressed in many normal tissues. MEG3 gene expression is lost in an expanding list of primary human tumors and tumor cell lines. Multiple mechanisms contribute to the loss of MEG3 expression in tumors, including gene deletion, promoter hypermethylation, and hypermethylation of the intergenic differentially methylated region. Re-expression of MEG3 inhibits tumor cell proliferation in culture and colony formation in soft agar. This growth inhibition is partly the result of apoptosis induced by MEG3. MEG3 induces accumulation of p53 (TP53) protein, stimulates transcription from a p53-dependent promoter, and selectively regulates p53 target gene expression. Maternal deletion of the MEG3 gene in mice results in skeletal muscle defects and perinatal death. Inactivation of MEG3 leads to a significant increase in expression of angiogenesis-promoting genes and microvessel formation in the brain. These lines of evidence strongly suggest that MEG3 functions as a novel lncRNA tumor suppressor.
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selective loss of MEG3 expression and intergenic differentially methylated region hypermethylation in the MEG3 dlk1 locus in human clinically nonfunctioning pituitary adenomas
The Journal of Clinical Endocrinology and Metabolism, 2008Co-Authors: Roger Gejman, Xun Zhang, Yunli Zhou, Ying Zhong, Dalia L. Batista, Brooke Swearingen, Constantine A. Stratakis, Tessa E Hedleywhyte, Anne KlibanskiAbstract:Context: MEG3 is an imprinted gene encoding a novel noncoding RNA that suppresses tumor cell growth. Although highly expressed in the normal human pituitary, it is unknown which of the normal pituitary cell types and pituitary tumors express MEG3. Objectives: Our objectives were 1) to investigate cell-type- and tumor-type-specific expression of MEG3 in the human pituitary and 2) to investigate whether methylation in the intergenic differentially methylated region (IG-DMR) at the DLK1/MEG3 locus is involved in the loss of MEG3 expression in tumors. Design and Methods: RT-PCR, quantitative RT-PCR, Northern blot, and a combination of in situ hybridization and immunofluorescence were used to determine the cell-type- and tumor-type-specific MEG3 expression. Bisulfite treatment and PCR sequencing of genomic DNA were used to measure the CpG methylation status in the normal and tumor tissues. Five normal human pituitaries and 17 clinically nonfunctioning, 11 GH-secreting, seven prolactin-secreting, and six ACTH-secreting pituitary adenomas were used. Results: All normal human pituitary cell types express MEG3. However, loss of MEG3 expression occurs only in nonfunctioning pituitary adenomas of a gonadotroph origin. All other pituitary tumor phenotypes examined express MEG3. Hypermethylation of the IG-DMR at the DLK1/MEG3 locus is present in nonfunctioning pituitary adenomas. Conclusions: MEG3 is the first human gene identified expressed in multiple normal human pituitary cell types with loss of expression specifically restricted to clinically nonfunctioning pituitary adenomas. The IG-DMR hypermethylation may be an additional mechanism for MEG3 gene silencing in such tumors.
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Selective loss of MEG3 expression and intergenic differentially methylated region hypermethylation in the MEG3/DLK1 locus in human clinically nonfunctioning pituitary adenomas.
The Journal of clinical endocrinology and metabolism, 2008Co-Authors: Roger Gejman, Xun Zhang, Yunli Zhou, Ying Zhong, Dalia L. Batista, Brooke Swearingen, Constantine A. Stratakis, E. Tessa Hedley-whyte, Anne KlibanskiAbstract:MEG3 is an imprinted gene encoding a novel noncoding RNA that suppresses tumor cell growth. Although highly expressed in the normal human pituitary, it is unknown which of the normal pituitary cell types and pituitary tumors express MEG3. Our objectives were 1) to investigate cell-type- and tumor-type-specific expression of MEG3 in the human pituitary and 2) to investigate whether methylation in the intergenic differentially methylated region (IG-DMR) at the DLK1/MEG3 locus is involved in the loss of MEG3 expression in tumors. RT-PCR, quantitative RT-PCR, Northern blot, and a combination of in situ hybridization and immunofluorescence were used to determine the cell-type- and tumor-type-specific MEG3 expression. Bisulfite treatment and PCR sequencing of genomic DNA were used to measure the CpG methylation status in the normal and tumor tissues. Five normal human pituitaries and 17 clinically nonfunctioning, 11 GH-secreting, seven prolactin-secreting, and six ACTH-secreting pituitary adenomas were used. All normal human pituitary cell types express MEG3. However, loss of MEG3 expression occurs only in nonfunctioning pituitary adenomas of a gonadotroph origin. All other pituitary tumor phenotypes examined express MEG3. Hypermethylation of the IG-DMR at the DLK1/MEG3 locus is present in nonfunctioning pituitary adenomas. MEG3 is the first human gene identified expressed in multiple normal human pituitary cell types with loss of expression specifically restricted to clinically nonfunctioning pituitary adenomas. The IG-DMR hypermethylation may be an additional mechanism for MEG3 gene silencing in such tumors.
Jun Zhang - One of the best experts on this subject based on the ideXlab platform.
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Hypermethylation of MEG3 promoter correlates with inactivation of MEG3 and poor prognosis in patients with retinoblastoma
Journal of translational medicine, 2017Co-Authors: Yali Gao, Peng Huang, Jun ZhangAbstract:In our previous study, we revealed that MEG3 was a tumor suppressor gene in retinoblastoma and inhibited proliferation of retinoblastoma cells by regulating the activity of the Wnt/β-catenin pathway. Here, we further explored the mechanism of MEG3 inactivation in retinoblastoma. MSP and qRT-PCR were performed to detect the methylation status of MEG3 promoter and levels of MEG3 expression, respective. To further explore relationship between MEG3 expression and epigenetic modifications, 5-Aza-CdR was used to interfere with DNA methylation. In addition, we evaluated proliferation, apoptosis and the expression of β-catenin via CCK-8, flow cytometric analysis and western blot analysis, respective. Hypermethylation of MEG3 promoter was observed more frequently in retinoblastoma tissues and was highly associated with low MEG3 expression and poor survival of retinoblastoma patients. We also provided evidence demonstrating that hypermethylation of MEG3 promoter depressed MEG3 expression, promoted proliferation, inhibited apoptosis and increased β-catenin expression of retinoblastoma cells in vitro. Our present study indicates that promoter silencing by hypermethylation may account for the loss of MEG3 expression and predict poor prognosis.
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Aberrant Methylation of MEG3 Functions as a Potential Plasma-Based Biomarker for Cervical Cancer
Scientific reports, 2017Co-Authors: Jun Zhang, Zhongqiu Lin, Tingting Yao, Yali GaoAbstract:Methylation alterations of specific genes have recently been identified as diagnostic biomarkers for human cancers. Although MEG3 has been proved to be a tumor suppressor in cervical cancer according to our previous study, the diagnostic value of MEG3 methylation in plasma is still unknown. Therefore, the aim of this study is to identify a novel epigenetic biomarker for cervical cancer. In the current study, the level of MEG3 methylation was evaluated using methylation-specific polymerase chain reaction. The results showed that the level of MEG3 methylation was significantly higher in cervical cancer tissues and patients’ plasmas than those in adjacent normal tissues and plasmas of healthy participants respectively. Moreover, the accuracy was good enough for MEG3 methylation in plasma to discriminate CIN III patients from healthy participants. In addition, MEG3 methylation in plasma also has high discriminating power to predict HR-HPV infection and lymph node metastasis. Furthermore, hypermethylation of MEG3 in plasma was associated with worse recurrence-free and overall survival in cervical cancer patients. In conclusions, MEG3 methylation in plasma can serve as a diagnostic and prognostic biomarker for cervical cancer, providing useful information for clinical management.
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downregulation of long noncoding rna MEG3 is associated with poor prognosis and promoter hypermethylation in cervical cancer
Journal of Experimental & Clinical Cancer Research, 2017Co-Authors: Yali Gao, Jun Zhang, Zhongqiu Lin, Tingting YaoAbstract:Our previous study reported that MEG3 is an important tumor suppressor gene that is inactivated in cervical cancer. However, the diagnostic and prognostic values of MEG3, as well as the molecular mechanism of MEG3 inactivation in cervical cancer, remain unclear. In this study, we aimed to further elucidate the role and potential inactivation mechanism of MEG3 in cervical cancer. ROC curve and Cox regression analyses were used to assess the diagnostic and prognostic value of MEG3 in patients with cervical cancer. The methylation status of the MEG3 promoter in cervical cancer tissue samples was tested using methylation-specific PCR. Furthermore, we altered the methylation status of the MEG3 promoter in two cervical cancer cell lines (HeLa and CaSki) using a DNA methylation transfer enzyme inhibitor (5-Aza-CdR), to investigate whether promoter hypermethylation is a potential cause of MEG3 inactivation. Finally, we used CCK-8 and colony formation assays to evaluate the cell proliferation ability of HeLa and CaSki cells that had been treated with 5-aza-CdR, to investigate whether downregulation of MEG3 caused by promoter hypermethylation had biological effects. ROC curve analysis indicated that MEG3 status showed sufficient sensitivity and specificity for prediction of tumor size and lymph node metastasis in patients with cervical cancer. In addition, our follow-up data showed that low MEG3 expression was correlated with recurrence and short overall survival. Moreover, hypermethylation of the MEG3 promoter was observed in most cervical cancer tissue samples, and demethylation of the MEG3 promoter led to re-expression of MEG3 and inhibited proliferation of HeLa and CaSki cells. MEG3 is a powerful tool for diagnosis and prognosis of patients with cervical cancer, and low expression of MEG3 is likely to be related to promoter hypermethylation in cervical cancer.
