Histone demethylase JMJD3 at the intersection of cellular senescence and cancer

JMJD3 suppresses tumor progression in oral tongue squamous cell carcinoma patients receiving surgical resection

Background

Jumonji domain-containing-3 (JMJD3) is reported to be a histone H3 lysine 27 (H3K27) demethylase and a tumor suppressor gene. The present study designed to investigate the crucial role of JMJD3 in oral tongue squamous cell carcinoma (OTSCC) patients who received surgical resection.

Methods

We enrolled a total of 156 OTSCC patients receiving surgical resection, including 73 patients (47%) with high expression of JMJD3 and 83 patients (53%) harboring low expression of JMJD3. Two OTSCC cell lines, SAS and Cal 27, were used to explore the modulation of cancer. GSK-J4, a potent inhibitor of JMJD3, was used to treat the two OTSCC cell lines. The Chi-square test was performed to examine between-group differences in categorical variables; the Kaplan-Meier method was used to investigate survival outcome in univariate analysis, and the Cox regression model was used for multivariate analysis.

Results

The median follow-up period was 59.2 months and he five-year disease-free survival (DFS) and overall survival (OS) rates were 46.2% and 50.0%, respectively. Better five-year DFS (59% versus 35%) and five-year OS (63% versus 39%) were mentioned in patients with high expression of JMJD3 compared to those with low expression of JMJD3. High expression of JMJD3 was significantly associated with superior DFS and OS in the univariate and multivariate analyses. Following successful inhibition of JMJD3 by GSK-J4, western blotting analysis showed the decreased expression of Rb and p21.

Conclusion

Our study showed that high expression of JMJD3 is a good prognostic factor in OTSCC patients who underwent surgical resection.

Emerging roles of JMJD3 in cancer

Histone lysine methylation plays a key role in gene activation and repression. The trimethylation of histone H3 on lysine-27 (H3K27me3) is a critical epigenetic event that is controlled by Jumonji domain-containing protein-3 (JMJD3). JMJD3 is a histone demethylase that specifically removes methyl groups. Previous studies have suggested that JMJD3 has a dual role in cancer cells. JMJD3 stimulates the expression of proliferative-related genes and increases tumor cell growth, propagation, and migration in various cancers, including neural, prostate, ovary, skin, esophagus, leukemia, hepatic, head and neck, renal, lymphoma, and lung. In contrast, JMJD3 can suppress the propagation of tumor cells, and enhance their apoptosis in colorectal, breast, and pancreatic cancers. In this review, we summarized the recent advances of JMJD3 function in cancer cells.

Disruption of Jmjd3/p16Ink4a Signaling Pathway Causes Bizarre Parosteal Osteochondromatous Proliferation (BPOP)-like Lesion in Mice

Bizarre parosteal osteochondromatous proliferation (BPOP), or Nora's lesion, is a rare benign osteochondromatous lesion. At present, the molecular etiology of BPOP remains unclear. JMJD3(KDM6B) is an H3K27me3 demethylase and counteracts polycomb-mediated transcription repression. Previously, Jmjd3 was shown to be critical for bone development and osteoarthritis. Here, we report that conditional deletion of Jmjd3 in chondrogenic cells unexpectedly resulted in BPOP-like lesion in mice. Biochemical investigations revealed that Jmjd3 inhibited BPOP-like lesion through p16^Ink4a . Immunohistochemistry and RT-qPCR assays indicated JMJD3 and p16^INK4A level were significantly reduced in human BPOP lesion compared with normal subjects. This was further confirmed by Jmjd3/Ink4a double-gene knockout mice experiments. Therefore, our results indicated the pathway of Jmjd3/p16^Ink4a may be essential for the development of BPOP in human. © 2021 American Society for Bone and Mineral Research (ASBMR).

Prognostic Significance of JMJD3 Expression in Pleural Mesotheliomas

Pleural mesothelioma is a disease associated with asbestos exposure and patients often have poor prognosis. Biomarkers that can stratify tumours more efficiently are much sought after to enable more personalized treatment options and predict prognosis. Jumonji domain-containing protein D3 (JMJD3) has variable expression in a range of tumours. However, there has been much discordance in the immunohistochemical labelling of JMJD3 between cancers at different sites and ambiguity exists regarding its functional significance. Recent evidence suggests that although nuclear expression of JMJD3 has a demethylase role in most cancers, there are also demethylase-independent actions of JMJD3 that need to be explored including its cytoplasmic expression. We analysed JMJD3 labelling in 99 pleural mesothelioma tissues and correlated nuclear and cytoplasmic expression with survival outcomes. We found that low nuclear and high cytoplasmic expression were associated with poor survival outcomes in our cohort (p = 0.014 and p = 0.041, respectively). Additionally, we found that low nuclear expression of JMJD3 was frequent in the sarcomatoid subtype (p < 0.001). Finally, we showed that cytoplasmic labelling is an independent prognostic marker of poor survival. Our cohort only contained a small number of tumours with high cytoplasmic expression of JMJD3, and a larger cohort study may provide clearer stratification.

Expression pattern of histone lysine-specific demethylase 6B in gastric cancer

Over the last few decades, predictive markers for the prognosis of gastric cancer have not been extensively investigated. The present study aimed to evaluate the expression profile of histone demethylase lysine (K)-specific demethylase 6B (KDM6B) in gastric cancer and healthy control tissues, as well as its value in prognosis prediction as a clinical marker. Within the framework of these criteria, the diagnostic role of KMD6B for gastric cancer was investigated, which may provide insights into novel treatment targets. Immunohistochemistry was applied to detect KMD6B expression in 100 gastric cancer tissues and matching para-cancerous tissues to analyze the association between KMD6B expression and clinicopathological features. Based on the follow-up data, the value of KMD6B in prognosis assessment was further explored. The role of KMD6B in gastric cancer cell proliferation, cell cycle distribution and the expression of cell cycle-associated proteins was investigated by inhibiting KMD6B activity using the specific inhibitor GSK J4. KMD6B was mostly distributed in cytoplasm and nucleus in gastric cancer tissue. The expression level was significantly higher in cancer tissues compared with that in the corresponding non-cancerous tissues. The expression of KMD6B was significantly associated with sex, lymph node and distant metastasis status and clinical stage (P<0.05). Cell proliferation was significantly decreased with the inhibition of KMD6B activity, and the cell cycle in HGC27 cells was arrested in the G₂/M phase after being treated with GSK J4 for 24 h. The expression of cyclin B and Cdc2 were significantly decreased, while p21 was upregulated. It was concluded that the dysregulated expression of KMD6B is associated with the malignant progression of gastric cancer and could be a potential marker for prognosis. Blocking the demethylase activity of KMD6B induced G₂/M arrest and inhibited the proliferation of gastric cancer cells, suggesting that KMD6B is a potential novel therapeutic target for gastric cancer.

KDM6B (JMJD3) and its dual role in cancer

Epigenetic modifications play a fundamental role in the regulation of gene expression and cell fate. During the development of cancer, epigenetic modifications appear that favor cell proliferation and migration, but at the same time prevent differentiation and apoptosis, among other processes. KDM6B is a histone demethylase that specifically removes methyl groups from H3K27me3, thus allowing re-expression of its target genes. It is currently known that KDM6B can act as both a tumor suppressor and an oncogene depending on the cellular context. Therefore, in this work we summarize the current knowledge of the role that KDM6B plays in different oncological contexts, and we try to orient it towards its clinical application.

Updated review on green tea polyphenol epigallocatechin-3-gallate as a cancer epigenetic regulator

In-depth insights in cancer biology over the past decades have highlighted the important roles of epigenetic mechanisms in the initiation and progression of tumorigenesis. The cancer epigenome usually experiences multiple alternations, including genome-wide DNA hypomethylation and site-specific DNA hypermethylation, various histone posttranslational modifications, and dysregulation of non-coding RNAs (ncRNAs). These epigenetic changes are plastic and reversible, and could potentially occur in the early stage of carcinogenesis preceding genetic mutation, offering unique opportunities for intervention therapies. Therefore, targeting the cancer epigenome or cancer epigenetic dysregulation with some selected agents (called epi-drugs) represents an evolving and promising strategy for cancer chemoprevention and therapy. Phytochemicals, as a class of pleiotropic molecules, have manifested great potential in modulating different cancer processes through epigenetic machinery, of which green tea polyphenol epigallocatechin-3-gallate (EGCG) is one of the most extensively studied. In this review, we first summarize epigenetic events involved in the pathogenesis of cancer, including DNA/RNA methylations, histone modifications and ncRNAs' dysregulations. We then focus on the recently discovered roles of phytochemicals, with a special emphasis on EGCG, in modulating different cancer processes through regulating epigenetic machinery. We finally discuss limitations of EGCG as an epigenetic modulator for cancer chemoprevention and treatment and offer potential strategies to overcome the shortcomings.

[Association of JMJD3, MMP-2 and VEGF expressions with clinicopathological features of invasive ductal breast carcinoma]

OBJECTIVE

To examine the expressions of JMJD3, matrix metalloproteinase-2 (MMP-2) and vascular endothelial growth factor (VEGF) in invasive ductal breast carcinoma, their association with the clinicopathological features of the patients and the effect of JMJD3 overexpression on proliferation and MMP-2 and VEGF expressions in breast cancer cells.

METHODS

The protein and mRNA expressions of JMJD3, MMP-2, and VEGF in invasive ductal breast carcinoma and paired adjacent tissues were detected by immunohistochemistry and RT-PCR, respectively, and their correlation with the clinicopathological characteristics of the patients was analyzed. Kaplan-Meier survival analysis was used to evaluate the correlation of JMJD3, MMP-2 and VEGF expression levels with the survival of the patients. In breast cancer MDA-MB-231 cells transfected with a JMJD3-expression plasmid, the expression of Ki67 was examined immunohistochemically, the cell proliferation was assessed with CCK8 assay, and the mRNA expressions of MMP-2 and VEGF were detected with RT-PCR.

RESULTS

Breast cancer tissues had significantly lower JMJD3 expression and higher MMP-2 and VEGF expressions at both the mRNA and protein levels than the adjacent tissue (P < 0.05). The positivity rates of JMJD3, MMP-2 and VEGF in breast cancer tissues were significantly correlated with tumor diameter, differentiation, TNM stage, lymph node metastasis, and molecular subtypes (P < 0.05). KaplanMeier analysis showed that JMJD3 expression level was positively while MMP-2 and VEGF were inversely correlated with the disease-free survival time of the patients (P < 0.05). Cox regression analysis identified JMJD3, MMP-2, VEGF and tumor differentiation as independent prognostic factors of breast cancer. Spearman correlation analysis suggested a negative correlation of JMJD3 with MMP2 (r=-0.569, P < 0.05) and VEGF (r=-0.533, P < 0.05) and a positive correlation between MMP2 and VEGF (r=0.923, P < 0.05). In MDA-MB-231 cells, overexpression of JMJD3 inhibited the proliferation of MDA-MB-231 cells and the expression of MMP-2 and VEGF.

CONCLUSIONS

The expressions of JMJD3, MMP-2 and VEGF in invasive ductal breast carcinoma are closely correlated to tumor proliferation, invasion, metastasis and prognosis and can be used for prognostic evaluation of breast cancer.

Regulating Methylation at H3K27: A Trick or Treat for Cancer Cell Plasticity

Properly timed addition and removal of histone 3 lysine 27 tri-methylation (H3K27me3) is critical for enabling proper differentiation throughout all stages of development and, likewise, can guide carcinoma cells into altered differentiation states which correspond to poor prognoses and treatment evasion. In early embryonic stages, H3K27me3 is invoked to silence genes and restrict cell fate. Not surprisingly, mutation or altered functionality in the enzymes that regulate this pathway results in aberrant methylation or demethylation that can lead to malignancy. Likewise, changes in expression or activity of these enzymes impact cellular plasticity, metastasis, and treatment evasion. This review focuses on current knowledge regarding methylation and de-methylation of H3K27 in cancer initiation and cancer cell plasticity.

The Emerging Roles of Heterochromatin in Cell Migration

Cell migration is a key process in health and disease. In the last decade an increasing attention is given to chromatin organization in migrating cells. In various types of cells induction of migration leads to a global increase in heterochromatin levels. Heterochromatin is required for optimal cell migration capabilities, since various interventions with heterochromatin formation impeded the migration rate of numerous cell types. Heterochromatin supports the migration process by affecting both the mechanical properties of the nucleus as well as the genetic processes taking place within it. Increased heterochromatin levels elevate nuclear rigidity in a manner that allows faster cell migration in 3D environments. Condensed chromatin and a more rigid nucleus may increase nuclear durability to shear stress and prevent DNA damage during the migration process. In addition, heterochromatin reorganization in migrating cells is important for induction of migration-specific transcriptional plan together with inhibition of many other unnecessary transcriptional changes. Thus, chromatin organization appears to have a key role in the cellular migration process.

The Prognostic Significance Of JMJD3 In Primary Sarcomatoid Carcinoma Of The Lung, A Rare Subtype Of Lung Cancer

Introduction

Primary sarcomatoid carcinoma of the lung (PSC) is a rare subtype of non-small cell lung cancer, which has a bad prognosis and lacks biomarkers for its diagnosis and prognosis. Recent studies suggested that KDM6B (lysine demethylase 6B), also known as Jumonji domain-containing protein D3 (JMJD3), plays an oncogenic role in various human cancers. However, abnormalities of JMJD3 in sarcomatoid carcinoma of the lung and its clinical prognostic significance have not been determined. Therefore, the present study aimed to ascertain the relationship between JMJD3 and PSC.

Materials and methods

In this study, immunohistochemistry (IHC) was performed to examine the expression of JMJD3 in a tissue microarray (TMA) containing 96 cases of PSC.

Result

Overexpression of JMJD3 was observed in nuclei of the PSC cells. Further analyses indicated that the overexpression of JMJD3 was significantly associated with tumor size, pN stage, and clinical stage. By univariate survival analysis, positive expression of JMJD3 was significantly correlated with shortened patient survival. More importantly, multivariate analysis identified JMJD3 as an independent prognostic factor for sarcomatoid carcinoma of the lung.

Conclusion

These findings provide evidence that JMJD3 protein levels, as examined by IHC, may act as a novel prognostic biomarker for patients with primary sarcomatoid carcinoma of the lung.

Biology and targeting of the Jumonji-domain histone demethylase family in childhood neoplasia: a preclinical overview

INTRODUCTION

Epigenetic mechanisms of gene regulatory control play fundamental roles in developmental morphogenesis, and, as more recently appreciated, are heavily implicated in the onset and progression of neoplastic disease, including cancer. Many epigenetic mechanisms are therapeutically targetable, providing additional incentive for understanding of their contribution to cancer and other types of neoplasia. Areas covered: The Jumonji-domain histone demethylase (JHDM) family exemplifies many of the above traits. This review summarizes the current state of knowledge of the functions and pharmacologic targeting of JHDMs in cancer and other neoplastic processes, with an emphasis on diseases affecting the pediatric population. Expert opinion: To date, the JHDM family has largely been studied in the context of normal development and adult cancers. In contrast, comparatively few studies have addressed JHDM biology in cancer and other neoplastic diseases of childhood, especially solid (non-hematopoietic) neoplasms. Encouragingly, the few available examples support important roles for JHDMs in pediatric neoplasia, as well as potential roles for JHDM pharmacologic inhibition in disease management. Further investigations of JHDMs in cancer and other types of neoplasia of childhood can be expected to both enlighten disease biology and inform new approaches to improve disease outcomes.

Epigenetic Regulation of EMT (Epithelial to Mesenchymal Transition) and Tumor Aggressiveness: A View on Paradoxical Roles of KDM6B and EZH2

EMT (epithelial to mesenchymal transition) is a plastic phenomenon involved in metastasis formation. Its plasticity is conferred in a great part by its epigenetic regulation. It has been reported that the trimethylation of lysine 27 histone H3 (H3K27me3) was a master regulator of EMT through two antagonist enzymes that regulate this mark, the methyltransferase EZH2 (enhancer of zeste homolog 2) and the lysine demethylase KDM6B (lysine femethylase 6B). Here we report that EZH2 and KDM6B are overexpressed in numerous cancers and involved in the aggressive phenotype and EMT in various cell lines by regulating a specific subset of genes. The first paradoxical role of these enzymes is that they are antagonistic, but both involved in cancer aggressiveness and EMT. The second paradoxical role of EZH2 and KDM6B during EMT and cancer aggressiveness is that they are also inactivated or under-expressed in some cancer types and linked to epithelial phenotypes in other cancer cell lines. We also report that new cancer therapeutic strategies are targeting KDM6B and EZH2, but the specificity of these treatments may be increased by learning more about the mechanisms of action of these enzymes and their specific partners or target genes in different cancer types.

KDM6B promotes ovarian cancer cell migration and invasion by induced transforming growth factor-β1 expression

KDM6B, also known as JMJD3, is a member of the family of histone lysine demethylase (KDMs), which is closely related to many types of cancers. However, its role and the underlying mechanisms in ovarian cancer remain unknown. Here we show that KDM6B is elevated in epithelial ovarian cancer and its expression level is closely related with metastasis and invasion. In addition, survival analysis showed that high expression of KDM6B was associated with low overall survival in ovarian cancer patients. Overexpression of KDM6B in epithelial ovarian cancer cells promoted proliferation, epithelial-mesenchymal transition (EMT), migration and invasion in vitro, and enhanced metastatic capacities in vivo. On the contrary, silencing KDM6B in invasive and metastatic ovarian cancer cells inhibited these processes. Mechanistically, we found that KDM6B exerts its function by modulating the transforming growth factor-β1 (TGF-β1) expression, and TGF-β1 signal pathway inhibitor LY2157299 significantly inhibited KDM6B-induced proliferation, migration, metastasis, and EMT in ovarian cancer cells. Our findings, for the first time, reveal the pivotal role of KDM6B in the invasion and metastatic behavior of epithelial ovarian cancer. Thus, targeting KDM6B may be a useful strategy to interfere with these behaviors of epithelial ovarian cancer.

Histone demethylase JARID1B/KDM5B promotes aggressiveness of non-small cell lung cancer and serves as a good prognostic predictor

Background

Lung cancer is the leading cause of cancer death worldwide. Recently, epigenetic dysregulation has been known to promote tumor progression and therefore may be a therapeutic target for anticancer therapy. JARID1B, a member of histone demethylases, has been found to be related to tumorigenesis in certain kinds of cancers. However, its biological roles in non-small cell lung cancer (NSCLC) remain largely unclear.

Methods

We firstly examined the expression of JARID1B in surgical specimens and six NSCLC cell lines. Then, we evaluated the relationship between JARID1B expression and clinicopathologic parameters in 72 NSCLC patients, thereby established its prognostic importance. We subsequently studied the functional roles of JARID1B in tumorigenesis to verify its clinicopathologic significance.

Results

Our results showed that JARID1B was overexpressed in NSCLC cells and JARID1B overexpression was associated with tumor size, lymph node metastasis, advanced stages, and poor overall survival in NSCLC patients. JARID1B overexpression resulted in increased cell proliferation and formation of tumorspheres and correlated positively with the expression of cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT) markers, while the c-Met signaling pathway was actively involved. It also correlated with the strength of resistance to cisplatin and doxorubicin. On the contrary, downregulation of JARID1B expression by applying shRNA or JARID1B inhibitor PBIT reversed these phenomena.

Conclusions

JARID1B worsens prognosis of NSCLC patients by promotion of tumor aggressiveness through multiple biological facets which were associated with activation of the c-Met signaling, and can be a novel prognostic biomarker and therapeutic target for NSCLC.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0533-9) contains supplementary material, which is available to authorized users.

Notch-effector CSL promotes squamous cell carcinoma by repressing histone demethylase KDM6B

Notch 1/2 genes play tumor-suppressing functions in squamous cell carcinoma (SCC), a very common malignancy in skin and internal organs. In contrast with Notch, we show that the transcription factor CSL (also known as RBP-Jκ), a key effector of canonical Notch signaling endowed with intrinsic transcription-repressive functions, plays a tumor-promoting function in SCC development. Expression of this gene decreased in upper epidermal layers and human keratinocytes (HKCs) undergoing differentiation, while it increased in premalignant and malignant SCC lesions from skin, head/neck, and lung. Increased CSL levels enhanced the proliferative potential of HKCs and SCC cells, while silencing of CSL induced growth arrest and apoptosis. In vivo, SCC cells with increased CSL levels gave rise to rapidly expanding tumors, while cells with silenced CSL formed smaller and more differentiated tumors with enhanced inflammatory infiltrate. Global transcriptomic analysis of HKCs and SCC cells with silenced CSL revealed major modulation of apoptotic, cell-cycle, and proinflammatory genes. We also show that the histone demethylase KDM6B is a direct CSL-negative target, with inverse roles of CSL in HKC and SCC proliferative capacity, tumorigenesis, and tumor-associated inflammatory reaction. CSL/KDM6B protein expression could be used as a biomarker of SCC development and indicator of cancer treatment.

Targeting estrogen receptor beta (ERβ) for treatment of ovarian cancer: importance of KDM6B and SIRT1 for ERβ expression and functionality

Estrogen receptor (ER) β has growth inhibitory and chemo drug potentiating effect on ovarian cancer cells. We studied the dependence of ERβ function on the presence of KDM6B and SIRT1 in human ovarian cancer cells in vitro. Activation of ERβ with the subtype-selective agonist KB9520 resulted in significant inhibition of human ovarian cancer cell growth. KB9520-activated ERβ had an additive effect on growth inhibition in combination with cisplatin and paclitaxel, respectively. Loss of KDM6B expression had a negative effect on ERβ function as a ligand-dependent inhibitor of ovarian cancer cell growth. In contrast, loss or inhibition of SIRT1 deacetylase activity restored ligand-activated ERβ functionality. Presented data suggest that selective targeting of ERβ with an agonist potentiate chemotherapy efficacy for the treatment of ovarian cancer and that downregulation or inhibition of SIRT1 may further enhance its therapeutic effect.

Calcitriol induces cell senescence of kidney cancer through JMJD3 mediated histone demethylation

Calcitriol, also known as 1,25-dihydroxyvitamin D3 (1,25(OH)₂VD₃), is a biologically active form of vitamin D and has a wide range of anticancer activity against various cancer cell lines. However, the mechanism of calcitriol remains to be further studied. In this study, the biological effect and epigenetic regulation of calcitriol on kidney cancer cells were investigated. Calcitriol can significantly inhibit cell proliferation of kidney cancer cell lines 786-O (P<0.05). Calcitriol also induced cell apoptosis and senescence of 786-O and ACHN (P<0.05). Calcitriol can increase the expression of histone demethylase JMJD3 and cell senescence marker p16INK4A (P<0.05). Knockdown of JMJD3 decreased p16INK4A upregulation after calcitriol treatment (P<0.05), and also reduced calcitriol-induced cell senescence (P<0.05). This study reveals a new mechanism of anticancer activity of calcitriol by showing that histone demethylase JMJD3 induced by calcitriol increases p16INK4A expression and cell senescence. Therefore, these results provide new strategy for treatment and prevention of kidney cancer.

Long noncoding RNA HOTAIR promotes metastasis of renal cell carcinoma by up-regulating histone H3K27 demethylase JMJD3

Long Noncoding RNAs (lncRNAs) are a kind of non-protein coding transcripts longer than 200 nucleotides, and play important roles in diverse biological processes, such as embryonic development and apoptosis. Homeobox (HOX) transcript antisense intergenic RNA (HOTAIR) is a negative prognostic factor in a variety of human cancers, such as breast, liver and lung cancers. HOTAIR can promote cancer cell metastasis by reprogramming chromatin organization. In the present study, HOTAIR expression was elevated in tissues of renal cell carcinoma compared to adjacent normal tissues, and positively correlated with metastasis (P<0.05). The cell migration was inhibited in scratch test and transwell assay after HOTAIR knockdown (P<0.05). Further researches revealed that histone demethylase JMJD3 was reduced and its target gene Snai1 expression was down-regulated after HOTAIR suppression (P<0.05). Meanwhile, the level of histone methytransferase EZH2 target gene PCDHB5 was increased (P<0.05). Collectively, these data suggest that HOTAIR is an important promoter in metastasis of renal cell carcinoma and also plays a dual regulatory role in chromatin state by effecting both histone metylation and demethylation at different gene loci.

The pharmacological role of histone demethylase JMJD3 inhibitor GSK-J4 on glioma cells

Glioma is regarded as the most prevalent malignant carcinoma of the central nervous system, and lack of effective treatment. Thus, the development of new therapeutic strategies targeting glioma is of significant clinical importance. In the present study, histone H3K27 demethylase jumonji domain-containing protein 3 (JMJD3) was investigated as target for glioma treatment. The mRNA of JMJD3 was overexpressed in glioblastoma tissues compared to normal brain tissues (P<0.05). The content of JMJD3 was also higher in glioma cells than in human brain microvascular endothelial cell (hCMEC), and the corresponding level of H3K27me3 was decreased (P<0.05). The treatment with JMJD3 specific inhibitor GSK-J4 can increase the content of H3K27me3 in glioma cells, which means the activity of JMJD3 was inhibited. GSK-J4 can inhibit glioma cell proliferation in a concentration dependent and time-dependent manner (P<0.05). GSK-J4 also induced glioma cell apoptosis and inhibited cell migration (P<0.05). But there was no obvious effect of GSK-J4 on hCMEC cells. All together, these data suggest that GSK-J4 has important potential in the gliomas treatment.

The Roles of Histone Demethylase Jmjd3 in Osteoblast Differentiation and Apoptosis

Posttranslational modifications including histone methylation regulate gene transcription through directly affecting the structure of chromatin. Trimethylation of histone 3 lysine 27 (H3K27me3) is observed at the promoters of a wide variety of important genes, especially for mammalian development, and contributes to gene silencing. Demethylase Jumonji domain-containing 3 (Jmjd3) catalyzes the transition of H3K27me3 to H3K27me1, therefore from a repressive to an active status of gene expression. Jmjd3 plays important roles in cell differentiation, inflammation, and tumorigenesis by targeting distinct transcription factors. In this review, we summarize the pivotal roles of Jmjd3 in maintaining skeletal homeostasis through regulating osteoblast differentiation, maturation, and apoptosis.