Histone Mark Profiling in Pediatric Astrocytomas Reveals Prognostic Significance of H3K9 Trimethylation and Histone Methyltransferase SUV39H1

Alterations in global histone methylation regulate gene expression and participate in cancer onset and progression. The profile of histone methylation marks in pediatric astrocytomas is currently understudied with limited data on their distribution among grades. The global expression patterns of repressive histone marks H3K9me3, H3K27me3, and H4K20me3 and active H3K4me3 and H3K36me3 along with their writers SUV39H1, SETDB1, EZH2, MLL2, and SETD2 were investigated in 46 pediatric astrocytomas and normal brain tissues. Associations between histone marks and modifying enzymes with clinicopathological characteristics and disease-specific survival were studied along with their functional impact in proliferation and migration of pediatric astrocytoma cell lines using selective inhibitors in vitro. Upregulation of histone methyltransferase gene expression and deregulation of histone code were detected in astrocytomas compared to normal brain tissues, with higher levels of SUV39H1, SETDB1, and SETD2 as well as H4K20me3 and H3K4me3 histone marks. Pilocytic astrocytomas exhibited lower MLL2 levels compared to diffusely infiltrating tumors indicating a differential pattern of epigenetic regulator expression between the two types of astrocytic neoplasms. Moreover, higher H3K9me3, H3K36me3, and SETDB1 expression was detected in grade IIΙ/IV compared to grade II astrocytomas. In univariate analysis, elevated H3K9me3 and MLL2 and diminished SUV39H1 expression adversely affected survival. Upon multivariate survival analysis, only SUV39H1 expression was revealed as an independent prognostic factor of adverse significance. Treatment of pediatric astrocytoma cell lines with SUV39H1 inhibitor reduced proliferation and cell migration. Our data implicate H3K9me3 and SUV39H1 in the pathobiology of pediatric astrocytomas, with SUV39H1 yielding prognostic information independent of other clinicopathologic variables.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13311-021-01090-x.     

Loss of NECL1, a novel tumor suppressor,can be restored in glioma by HDAC inhibitor‐Trichostatin A through Sp1 binding site

Nectin‐like molecule 1 (NECL1)/CADM3/IGSF4B/TSLL1/SynCAM3 is a neural tissue‐specific immunoglobulin‐like cell–cell adhesion molecule downregulated at the mRNA level in 12 human glioma cell lines. Here we found that the expression of NECL1 was lost in six glioma cell lines and 15 primary glioma tissues at both RNA and protein levels. Re‐expression of NECL1 into glioma cell line U251 would repress cell proliferation in vitro by inducing cell cycle arrest. And also NECL1 could decrease the growth rate of tumors in nude mice in vivo. To further investigate the mechanism why NECL1 was silenced in glioma, the basic promoter region located at ?271 to +81 in NECL1 genomic sequence was determined. DNA bisulfite sequencing was performed to study the methylation status of CpG islands in NECL1 promoter; however, no hypermethylated CpG site was found. Additionally, the activity of histone deacetylase (HDACs) in glioma was higher than that in normal brain tissues, and the expression of NECL1 in glioma cell lines could be reactivated by HDACs inhibitor‐Trichostatin A (TSA). So the loss of NECL1 in glioma was at least partly caused by histone deacetylation. Luciferase reporter assays, chromatin immunoprecipitation and co‐immunoprecipitation (co‐IP) assays indicated that Sp1 played an important role in this process by binding to either HDAC1 in untreated glioma cells or p300/CBP in TSA treated cells. Our finding suggests that NECL1 may act as a tumor suppressor in glioma and loss of it in glioma may be caused by histone deacetylation. © 2008 Wiley‐Liss, Inc.     

TIMP-2基因对人脑胶质瘤U87细胞周期与增殖的影响

目的探讨金属蛋白酶组织抑制因子(TIMP-2)对人脑胶质瘤细胞的抑制作用,主要是对细胞周期与细胞增殖的作用.方法用含TIMP-2基因的重组腺病毒载体,体外转染人胶质瘤细胞系U87,用Western blot检测目的蛋白的表达.通过细胞生长实验,流式细胞仪分析技术检测U87转染前后细胞增殖、周期与凋亡的变化.结果转染AdTIMP-2病毒后的U87细胞TIMP-2蛋白表达上调,转染后对U87细胞的生长有抑制作用,并出现明显的G0 -G1 期阻滞,但无明显的细胞凋亡峰出现.结论重组腺病毒载体介导的TIMP-2基因在体外对人脑胶质瘤细胞系U87 的生长有抑制作用,可作为胶质瘤治疗的有效工具.     

Histone deacetylase 11 regulates oligodendrocyte-specific gene expression and cell development in OL-1 oligodendroglia cells

Both in vivo and in vitro studies indicate a correlation between reduced acetylation of histone core proteins and oligodendrocyte development. The nature of these histone modifications and the mechanisms mediating them remain undefined. To address these issues, we utilized OL-1 cells, a rat nontransformed oligodendrocyte cell line, and primary oligodendrocyte cultures. We found that the acetylated histone H3 at lysine 9 and lysine 14 (H3K9/K14ac) is reduced in both the myelin basic protein (MBP) and proteolipid protein (PLP) genes of maturing oligodendroglial OL-1 cells, and furthermore, this temporally correlates with increases in MBP, PLP, and histone deacetylase (HDAC) 11 expression. Disruption of developmentally-regulated histone H3 deacetylation within the MBP and PLP genes by the HDAC inhibitor trichostatin A blunts MBP and PLP expression. With its increased expression, interaction of HDAC 11 with acetylated histone H3 and recruitment of HDAC 11 to the MBP and PLP genes markedly increases in maturing OL-1 cells. Moreover, suppressing HDAC 11 expression with small interfering RNA significantly (1) increases H3K9/K14ac globally and within the MBP and PLP genes, (2) decreases MBP and PLP mRNA expression, and (3) blunts the morphological changes associated with oligodendrocyte development. Our data strongly support a specific role for HDAC 11 in histone deacetylation and in turn the regulation of oligodendrocyte-specific protein gene expression and oligodendrocyte development.     

丙戊酸对胶质瘤细胞株T98-G体外作用实验研究

目的 研究抗癫痫常用药物丙戊酸(2-propylpentanoic acid,VPA)临床治疗浓度对人脑胶质瘤细胞株T98-G增殖抑制、细胞周期及组蛋白乙酰化的影响,并探讨其意义.方法 四甲基偶氮唑蓝(MTT)比色法检测VPA对胶质瘤细胞株T98-G的细胞毒性作用;流式细胞术检测其对细胞周期动力学及其对细胞凋亡的影响;Western blot法检测胶质瘤细胞株在VPA处理后乙酰化组氨酸H3(Acetyl-Histone H3)、乙酰化组氨酸H4(Acetyl-Histone H4)的表达量变化.结果 丙戊酸对胶质瘤细胞株T98-G具有抑制增殖作用,随着药物浓度的增加,抑制作用增强;临床常用浓度(1.0 mmol/L)VPA能够对细胞周期动力学产生影响,S期细胞减少,而G1期、G2/M期细胞增加;Aceyl-HistoneH3、Aceyl-HistoneH4蛋白表达量明显上调.结论 VPA能够抑制胶质瘤细胞生长,引起细胞周期阻滞,其作用可能与其抑制组蛋白去乙酰化酶活性有关.     

Hax-1对胶质瘤细胞增殖、迁移和侵袭的作用

目的 探讨造血干细胞特异性相关结合蛋白-1(Hax-1)对胶质瘤细胞增殖、迁移和侵袭的影响.方法 选择2018年9月至2019年6月手术切除并得到术后病理证实的胶质瘤组织35例和颅脑损伤内减压术切除的正常脑组织35例,采用qRT-PCR检测Hax-1 mRNA水平;同时检测胶质瘤细胞系(U87、A172、T98及U34...     

Lovastatin and phenylacetate induce apoptosis, but not differentiation, in human malignant glioma cells

Induction of differentiation is an attractive approach to the management of infiltrative tumors such as malignant glioma. Here, we report that lovastatin and phenylacetate induce apoptosis, but fail to induce differentiation, in malignant glioma cell lines and untransformed rat astrocytes. Lovastatin and phenylacetate promote p21 accumulation but fail to induce cell cycle arrest. BCL-2 gene transfer inhibits apoptosis induced by lovastatin but not apoptosis induced by phenylacetate. Wild-type p53 gene transfer promotes lovastatin-induced apoptosis in p53 wild-type LN-229 cells but not in p53 mutant T98G cells. Phenylacetate-induced apoptosis is attenuated by wild-type p53 gene transfer in both cell lines. Neither lovastatin nor phenylacetate modulate glioma cell sensitivity to CD95 ligand-induced apoptosis or cancer chemotherapy. Thus, this study provides no rationale for clinical trials of lovastatin or phenylacetate in the differentiation therapy of malignant glioma. We conclude that neoplastic glioma cells as well as untransformed rat astrocytes are refractory to the induction of differentiation by lovastatin and phenylacetate.     

CD81, a cell cycle regulator, is a novel target for histone deacetylase inhibition in glioma cells

Recent advances in cancer cell biology have focused on histone deacetylase inhibitors (HDACi's) because they target pathways critical to the development and progression of disease. In particular, HDACi's can induce expression of epigenetically silenced genes that promote growth arrest, differentiation and cell death. In glioma cells, one such repressed gene is the tetraspanin CD81, which regulates cytostasis in various cell lines and in astrocytes, the major cellular component of gliomas. Our studies show that HDACi's, trichostatin and sodium butyrate, promote growth arrest and differentiation with negligible cell death in glioma cells and induce expression of CD81 and cyclin-dependent kinase inhibitor 1A (p21(CIP/WAF-1)), another regulator of cytostasis in astrocytes. Interference RNA knock-down of CD81 abrogates cytostasis promoted by HDAC inhibition indicating that HDACi-induced CD81 is responsible for growth arrest. Induction of CD81 expression through HDAC inhibition is a novel strategy to promote growth arrest in glioma cells.     

组蛋白H3乙酰化对脑胶质瘤中Nanog基因的调控作用

目的：探讨组蛋白H3乙酰化修饰对脑胶质瘤增殖相关标记因子Nanog的调控作用。方法体外培养胶质瘤U87细胞,用不同浓度的Apicidin在不同时间内干预U87细胞作为实验组,另设加入DMSO溶剂的DMSO组,及不加药的空白对照组。MTT增殖实验观察Apicidin对细胞增殖的影响,并选出合适的干预浓度。Real-time PCR检测Nanog mRNA表达水平变化,Western blot检测组蛋白H3乙酰化及Nanog蛋白水平,染色质免疫共沉淀（ChIP） Real-time PCR技术检测Nanog启动子区域组蛋白H3乙酰化水平。结果 MTT结果显示：实验组细胞生长出现显著抑制,48 h内细胞增殖的半数抑制浓度IC50为（1.74±0.13）μmol/L。与空白对照组比较,实验组脑胶质瘤U87细胞中Nanog mRNA表达降低46.52%±0.53%（P＜0.05）,H3乙酰化水平和Nanog蛋白也均明显降低（P＜0.05）,实验组Nanog启动子区组蛋白H3乙酰化水平降低46.52%±0.82%（P＜0.05）。结论在脑胶质瘤细胞系中,组蛋白H3低乙酰化水平抑制Nanog表达,Nanog受组蛋白H3乙酰化修饰的调控。     

Characterizing the Role of PCDH9 in the Regulation of Glioma Cell Apoptosis and Invasion

PCDH9, a member of the protocadherin superfamily, is frequently lost in many different cancer types. This study aimed to detect PCDH9 expression in glioma tissues. This study also assessed the effects of PCDH9 expression in two different glioma cell lines. This was accomplished by manipulating PCDH9 expression in these glioma cell lines. The data showed that the expression of PCDH9 mRNA and protein was significantly decreased in gliomas compared to normal brain tissues. Lentivirus carrying PCDH9 cDNA restored PCDH9 expression in the U87 and U251 glioma cell lines. PCDH9 restoration in these cell lines reduced tumor cell viability, induced apoptosis, and caused G0/G1 cell cycle arrest. PCDH9 expression also suppressed the colony formation ability and invasion capacity of U87 and U251 cells. Molecularly, the restoration of PCDH9 expression upregulated Bax protein expression, but downregulated Bcl-2 and cyclin D1 expression. These data from the current study suggest that the loss of PCDH9 expression could contribute to glioma development and/or progression. Further studies will evaluate PCDH9 expression as a biomarker for the early detection of gliomas and as a prognostic indicator for this cancer type.     

Insulin-like growth factor-I decreased etoposide-induced apoptosis in glioma cells by increasing bcl-2 expression and decreasing CPP32 activity

AIMS: In a variety of tumors, the susceptibility of the tumor cells to apoptotic cell death following chemotherapy is a major determinant of therapeutic outcome. Gliomas are resistant to most chemotherapeutic agents, and its mechanism is not known in detail. In an attempt to understand the mechanism of chemo-resistance, we investigated the roles of insulin-like growth factor-I (IGF-I), IGF-I receptors (IGF-IR), and their relationship with the apoptotic response of two glioma cell lines to etoposide, a chemotherapeutic agent for malignant gliomas. METHODS: Two human glioma cell lines, U-87MG and KNS-42, were used. Etoposide-induced cell growth inhibition was quantified using a modified MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrasodium bromide), colorimetric assay. Hoechst 33258 staining, DNA fragmentation assay, and western blot were used for the evaluation of apoptosis. ApoAlert caspase assay was used for measuring the activity of caspase-3 (CPP32) and interleukin-1 beta -converting enzyme (ICE) protease. In addition, the effect of IGF-IR antisense was tested in U-87MG and KNS-42 glioma cell lines. RESULTS: Etoposide inhibited the growth of U-87MG and KNS-42 cells in a concentration-dependent manner. Etoposide increased the expression of wild-type p53, activated CPP32 (but not ICE) activity, and induced apoptosis in these cells. IGF-I prevented etoposide-induced apoptosis by increasing the expression of bcl-2 and decreasing the activity of CPP32. IGF-IR antisense enhanced the apoptotic effect of etoposide. CONCLUSIONS: IGF-I decreased etoposide-induced apoptosis in glioma cells by increasing the expression of bcl-2 and decreasing the activity of CPP32. The antisense of IGF-IR increased etoposide-induced apoptosis. The anti-apoptotic effect of IGF-I and IGF-IR might be related to the chemo-resistance of glioma to chemotherapeutic agents.     

STIP1对胶质瘤U251细胞增殖、侵袭和凋亡的影响

目的 探讨下调磷酸化应激诱导蛋白1（STIP1）表达对胶质瘤U251细胞增殖、侵袭和凋亡的影响,及其对JAK2/STAT3信号通路的调控作用。方法 免疫印迹法检测体外培养的正常胶质细胞（SVG）和人胶质瘤细胞（U251、U87和U37）STIP1蛋白表达水平。NC-siRNA或STIP1-siRNA质粒转染U251细胞,CCK-8法检测U251细胞增殖;Transwell实验检测U251细胞侵袭能力;流式细胞术检测U251细胞凋亡率;免疫印迹法检测JAK2/STAT3信号通路蛋白表达水平。结果 与正常胶质细胞SVG比较,胶质瘤细胞U251、U87和U373的STIP1蛋白表达水平均明显增高（P<0.05）。与NC-siRNA组比较,STIP1-siRNA组STIP1蛋白表达水平、细胞增殖活力和细胞侵袭力明显明显降低（P<0.05）,细胞凋亡率明显增高（P<0.05）,而且,p-JAK2和p-STAT3蛋白表达水平明显降低（P<0.05）。结论 STIP1在胶质瘤细胞中呈高表达,抑制STIP1表达可以抑制胶质瘤细胞的增殖和侵袭、促进凋亡,机制可能与抑制JAK2/STAT3信号通路有关。     

Alterations in cytokinetics and heat shock protein (70 kDa) expression of glial cell by hyperthermia]

Expression of major heat shock and stress-induced protein, HSP70, is known to be under complex regulation in tumor cells. In this study, we investigated the alternations of cytokinetics and HSP70 expression by hyperthermia in the in vitro experimental systems, using two rat glioma cell lines, two human glioblastoma cell lines and rat glioblast cells. For hyperthermal treatment the flasks were placed in water baths warmed up at 41 -45 degrees C for 15 min. To determine the effect of hyperthermia on the cell cycle progression, the changes in the DNA distribution of the cell population were studied by flow cytometry (FCM). The levels of HSP70 protein were determined by immunoblot analysis. The relationship between cell cycle and HSP70 expression was investigated by FCM using PI and FITC-labelled HSP70 double staining technique. These results were as follows: 1) Compared with the control, hyperthermic treatment at 42 degrees C or 44 degrees C caused both 354A and T98G cells to accumulate in S phase 18 hours after treatment and G2/M phase after 6-18 hours. 2) Hyperthermic treatment at 42 degrees C caused C6 cells to accumulate in S phase 6 hours after treatment, whereas heat treatment at 44 degrees C caused C6 cells to accumulate in S phase after 18 hours and G2/M phase after 6 hours. 3) A172 cells were accumulated only in G2/M phase by hyperthermia. 4) Glioblast cells did not show the alterations of cytokinetics by heat treatment remarkably. 5) HSP70 protein synthesis were enhanced under hyperthermic conditions in all type of cells, whether primary glioblast or permanent glioma cell lines.(ABSTRACT TRUNCATED AT 250 WORDS)     

Caveolin-1 expression is maintained in rat and human astroglioma cell lines

Caveolin-1 is the principal structural and functional component of caveolae, a plasmalemmal compartment that has been proposed to sequester lipid and protein components that participate in transmembrane signal transduction processes. Multiple studies reveal a reduction in the expression level of caveolin-1 mRNA and protein in many carcinomas as well as transformed cells. The human caveolin-1 gene is localized to a suspected tumor suppressor locus (7q31.1). Collectively, these data have been taken to imply that caveolin-1 may function in a tumor suppressor capacity. To determine if a reduction in the expression level of caveolin-1 mRNA and protein accompanied the transformation of astrocytes, we undertook studies of two transformed rat astroglial cell lines, C6 and DI TNC(1), as well as several cell lines derived from human glioblastoma tumors: T98G, U87MG, U118MG, U138MG, and U373MG. Ultrastructural, immunolocalization, immunoblot, and Northern blot analyses demonstrated that caveolin-1 message and protein were expressed in all rat and human glioma cells. The localization pattern, buoyant density, and detergent-insolubility property of caveolin-1 protein were indistinguishable from that determined for nontransformed type 1 astrocytes in culture. Nucleotide sequence analyses of caveolin-1 cDNAs indicate that mutations are not present in the caveolin-1 sequence in any of the glioma cell types. Taken together with previous analyses, these data indicate that, at least for astrocytes, the process of transformation in and of itself is not solely sufficient to reduce the level of caveolin-1 expression, and that caveolin-1 expression in and of itself is not solely sufficient to prevent the acquisition of a transformed phenotype.     

三个不同位点组蛋白修饰在人脑胶质瘤中的意义

目的 探讨组蛋白修饰与人脑胶质瘤发生及病理分级的关系.方法 选取西京医院神经外科自2006年至2008年病理确诊的胶质瘤患者肿瘤组织标本67例,采用免疫组织化学方法,检测组蛋白3个位点(H4K12Ac、H4R3monoMe、H4K20triMe)的修饰水平,并对结果进行统计学分析.结果 组蛋白3个位点在胶质瘤中均有修饰,有2个位点(H4K12Ac、H4R3monoMe)的修饰水平随胶质瘤病理级别的增高而升高,差异有统计学意义(P＜0.05),H4K20triMe的修饰水平则与肿瘤的病理级别无明显相关.结论 组蛋白修饰与人脑胶质瘤的发生有关,且修饰水平的变化与病理级别相关.     

miR-106a抑制胶质瘤细胞增殖并诱导凋亡

目的胶质瘤是最常见的原发性中枢神经系统肿瘤,具有较高的病死率。现有的研究表明miR-106a在多种肿瘤中表达上调,并发挥着致癌性作用,但miR-106a在胶质瘤中的表达和作用却并不清楚。方法不同级别胶质瘤组织和胶质瘤细胞系(T98G,SHG44,U87,U251,U373)内的miR-106a水平通过实时定量聚合酶链式反应(qRT-PCR)测定。转染miRNA寡聚核苷酸后的U87和U251细胞的增殖能力和细胞周期分别采用四甲基偶氮唑盐(MTT)比色法和流式细胞仪测定,并且通过膜联蛋白/碘化丙啶(annexin V/PI)双染法测定了miR-106a对胶质瘤细胞的凋亡影响。结果miR-106a在胶质瘤组织和胶质瘤细胞系内表达水平相对正常脑组织显著下降,并且miR-106a表达水平与胶质瘤病理级别负相关。胶质瘤细胞转染miR-106a后,可检测到过表达的miR-106a可显著抑制胶质瘤细胞的增殖能力,阻滞细胞周期于G0/G1期,同时诱导胶质瘤细胞凋亡增加。结论 miR-106a可阻滞胶质瘤细胞细胞周期、抑制增殖和诱导凋亡。     

Notch1通路与胶质瘤细胞管道形成能力相关性研究

目的探索胶质瘤细胞来源的管道(glioma clls derived vessels,GCDV)的形成机制。方法将胶质瘤细胞株U87、U251、U373、SF295、T98G、SKMG-4和C6进行体外三维培养,观察其管道形成能力。Western blot检测各个胶质瘤细胞株Notch1、Dll4蛋白的表达情况。结果三维培养C6细胞单个视野下(100×)的平均管道数(25.2±5.0)个,U373为(36.4±3.20)个,U87为(19.0±2.2)个,T98G为(12.6±2.4)个,SF295为(4.0±2.)个,U251为(0.2±0.4)个,SKMG-4为0。Notch1在U87、U251、T98G、SF295、SKMG-4、C6、U373表达相关密度分别为0.34、0.21、0.79、0.04、0.28、1.75、1.19,与管道形成能力显著相关(r=0.778,P=0.019);Dll4表达相关密度与管道形成能力不相关(r=0.635,P=0.062)。结论 Notch1蛋白表达与细胞株管道形成能力密切相关,而Dll4蛋白的表达与细胞株管道形成能力有待进一步探索。