Histone demethylase JHDM2A regulates H3K9 dimethylation in response to arsenic-induced DNA damage and repair in normal human liver cells

Long-term arsenic exposure is a worldwide public health problem that causes serious harm to human health. The liver is the main target organ of arsenic toxicity; arsenic induces disruption of the DNA damage repair pathway, but its mechanisms remain unclear. In recent years, studies have found that epigenetic mechanisms play an important role in arsenic-induced lesions. In this study, we conducted experiments in vitro using normal human liver cells (L-02) to explore the mechanism by which the histone demethylase JHDM2A regulates H3K9 dimethylation (me2) in response to arsenic-induced DNA damage. Our results indicated that arsenic exposure upregulated the expression of JHDM2A, downregulated global H3K9me2 modification levels, increased the H3K9me2 levels at the promoters of base excision repair (BER) genes (N-methylpurine-DNA glycosylase [MPG], XRCC1 and poly(ADP-ribose)polymerase 1) and inhibited their expression levels, causing DNA damage in cells. In addition, we studied the effects of overexpression and inhibition of JHDM2A and found that JHDM2A can participate in the molecular mechanism of arsenic-induced DNA damage via the BER pathway, which may not be involved in the BER process because H3K9me2 levels at the promoter region of the BER genes were unchanged following JHDM2A interference. These results suggest a potential mechanism by which JHDM2A can regulate the MPG and XRCC1 genes in the process of responding to DNA damage induced by arsenic exposure and can participate in the process of DNA damage repair, which provides a scientific basis for understanding the epigenetic mechanisms and treatments for endemic arsenic poisoning.     

NLRP3 inflammasome activation involved in LPS and coal tar pitch extract‐induced malignant transformation of human bronchial epithelial cells

Inflammatory microenvironment has been found as a new characteristic of cancer; however, the mechanisms of inflammation‐related lung cancer remain unclear. To explore the role of NLRP3 inflammsome activation in inflammation‐related lung carcinogenesis, a cell model was set up. Human bronchial epithelial cells (BEAS‐2B) were stimulated with 1 μg/mL lipopolysaccharide (LPS) for 24 hours, and then treated with 2.4 μg/mL coal tar pitch extract (CTPE) for 24 hours, after removal of LPS and CTPE, the cells were numbered passage 1 and were passaged and treated in this way until passage 30, which was called LPS + CTPE group. DMSO and Saline were used as vehicle controls. Malignant transformation of cells in passage 30 was evaluated by morphological change, platelet clone formation assay, and tumor formation in nude mice. The mRNA levels of NLRP3 and IL‐1β were detected by real time‐PCR. The combination of NLRP3 and caspase‐1 were determined using immunofluorescence and confocal. The protein expression of NLRP3, cleaved caspase‐1(p10), and cleaved IL‐1β was detected using Western blot. It was shown that CTPE, LPS + CTPE‐stimulated BEAS‐2B cells of passage 30 changed a lot morphologically. The clone formation rates, the rates of positive cells of NLRP3 and caspase‐1 combination, the mRNA levels of NLRP3 and IL‐1β, the protein expression of NLRP3, cleaved caspase‐1(p10) and cleaved IL‐1β of cells exposed with CTPE and LPS + CTPE at passage 30 were significantly increased compared to vehicle controls. Furthermore, the ability of tumor formation in nude mice, the rates of clone formation and positive cells, mRNA and protein levels of NLRP3 inflammasome activation‐related factors in LPS + CTPE‐induced cells were all higher than those in cells stimulated with CTPE alone. In conclusion, the cell model of inflammation‐related lung cancer is set up successfully, and NLRP3 inflammasome activation may be involved in the malignant transformation of BEAS‐2B cells which induced by CTPE alone or LPS combined with CTPE.     

Novel compounds protect auditory hair cells against gentamycin-induced apoptosis by maintaining the expression level of H3K4me2

Aminoglycoside-induced hair cell (HC) loss is a major cause of hearing impairment, and the effective prevention of HC loss remains an unmet medical need. Epigenetic mechanisms have been reported to be involved in protecting cochlear cells against ototoxic drug injury, and in this study we developed new bioactive compounds that have similar chemical structures as the epigenetics-related lysine-specific demethylase 1 (LSD1) inhibitors. LSD1 inhibitors have been reported to protect cochlear cells by preventing demethylation of dimethylated histone H3K4 (H3K4me2). To determine whether these new compounds exert similar protective effects on HCs, we treated mouse cochlear explant cultures with the new compounds together with gentamycin. There was a severe loss of HCs in the organ of Corti after gentamycin exposure, while co-treatment with the new compounds significantly protected against gentamycin-induced HC loss. H3K4me2 levels in the nuclei of HCs decreased after exposure to gentamycin, but H3K4me2 levels were maintained in the presence of the new compounds. Apoptosis is also involved in the injury process, and the new compounds protected the inner ear HCs against apoptosis by reducing caspase-3 activation. Together, our findings demonstrate that our new compounds prevent gentamycin-induced HC loss by preventing the demethylation of H3K4me2 and by inhibiting apoptosis, and these results might provide the theoretical basis for novel drug development for hearing protection.     

环磷酰胺诱发永生化人支气管上皮细胞的恶性转化

研究环磷酰胺 (CP)对人类支气管上皮细胞的致癌转化效应 .实验利用永生化人支气管上皮细胞(BEAS 2B)为靶细胞模型 ,研究CP诱导的BEAS 2B细胞 (BEAS CP)的恶性转化 ,并伴随研究了BEAS CP转化细胞的增殖动力学 ,细胞周期和非贴壁依赖性生长等转化表型特征 .结果显示 ,经传代和软琼脂培养基筛选 ,BEAS CP细胞已具有较为稳定的转化表型和细胞生物学特性 ,可能是具有裸小鼠致瘤性的恶性转化细胞 .结果表明CP对BEAS 2B细胞具有恶性转化效应     

Epigenetic modification of H3K4 and oxidative stress are involved in MC‐LR‐induced apoptosis in testicular cells of SD rats

Microcystin‐leucine arginine (MC‐LR) is a cyclic heptapeptide, produced by aquatic cyanobacteria such as microcystis, with strong reproductive toxicity which poses greater threat to the reproductive abilities of humans and animals. By exploring the role of trimethylation of histone H3 at lysine 4 (H3K4me3) and the role of oxidative stress in MC‐LR‐induced apoptosis in testicular Sertoli cells in Sprague‐Dawley (SD) rats, this study indicated that MC‐LR increased the expression levels of apoptosis‐related genes by raising the levels of H3K4me3. 5′‐Deoxy‐5′‐methylthioadenosine (MTA), the inhibitor of H3K4me3, reduced apoptosis, indicating for the first time that epigenetic modification is closely related to the testicular reproductive toxicity induced by MC‐LR. MC‐LR also induced oxidative stress by stimulating the generation of reactive oxygen species (ROS), and subsequently triggering mitochondria‐mediated apoptotic pathway by decreasing mitochondrial membrane potential and increasing the levels of Bax, Bcl‐2, Caspase‐3, and so on. MC‐LR‐induced apoptosis of testicular cells could be decreased after pretreatment with oxidative stress inhibitor N‐acetyl‐cysteine (NAC). Furthermore, the pathological damage to mitochondria and testes were observed in SD rats. These results show that MC‐LR can induce apoptosis by raising the levels of H3K4me3, and pretreatment with MTA can ameliorate the MC‐LR‐induced apoptosis of cocultured cells by lowering the levels of H3K4me3. Furthermore, NAC has a protective effect on MC‐LR‐induced apoptosis of testicular cells in SD rats by inhibiting the oxidative stress.     

H3K9 acetylation change patterns in rats after exposure to traffic-related air pollution

Traffic-related air pollution (TRAP) has been acknowledged as a potential risk factor for numerous respiratory disorders including lung cancer; however, the exact mechanisms involved are still unclear. Here we investigated the effects of TRAP exposure on the H3K9 acetylation in rats. The exposure was performed in both spring and autumn with identical study procedures. In each season, 48 healthy Wistar rats were exposed to different levels of TRAP for 4 h, 7 d, 14 d, and 28 d, respectively. H3K9 acetylation levels in both the peripheral blood mononuclear cells (PBMCs) and lung tissues were quantified. Multiple linear regression was applied to assess the influence of air pollutants on H3K9 acetylation levels. The levels of PM_2.5, PM₁₀, and NO₂ in the tunnel and crossroad groups were significantly higher than in the control group. The H3K9 acetylation levels were not significantly different between spring and autumn. When spring and autumn data were analyzed together, no significant association between the TRAP and H3K9 acetylation was found in 4 h exposure window. However, in the 7 d exposure window, PM_2.5 and PM₁₀ exposures were associated with changes in H3K9 acetylation ranging from 0.276 (0.053, 0.498) to 0.475 (0.103, 0.848) per 1 μg/m³ increase in the pollutant concentration. In addition, prolonged exposure of the rats in the tunnel showed that both PM_2.5 and PM₁₀ concentrations were positively associated with H3k9 acetylation in both PBMCs and lung tissues. The findings showed that 7-d and prolonged TRAP exposure could effectively increase the H3K9 acetylation level in both PBMCs and lung tissues of rats.     

塞替派诱发永生化人支气管上皮细胞的恶性转化（一）

目的 研究塞替派对人类支气管上皮细胞的致癌转化效应。方法 利用永生化人支气管上皮细胞（BEAS－2B）为靶细胞模型,以塞替派诱导BEAS－2B细胞的恶性转化,并伴随研究了塞替派转化细胞（EBAS－TE）的增殖动力学、细胞周期和锚着独立生长能力等转化表型特征。结果 经传代和软琼脂培养基筛选,BEAS－TE具有较为稳定的转化表型和细胞生物学特性。结论 塞替派对人支气管上皮细胞具有较强的恶性转化效应。     

塞替派诱发人支气管上皮恶性转化成瘤细胞的基因突变

目的　旨在了解转化细胞在成瘤过程中的p15 ,p16 ,p5 3和K ras基因编码序列突变情况。方法　运用逆转录聚合酶链反应 (RT PCR)技术和DNA测序技术。结果　转化各阶段细胞p15和K ras基因编码序列为野生型。在转化进程中 ,各转化细胞均携带与细胞永生化有关的p5 3第 4 7密码子CCG→TCG(脯氨酸→丝氨酸 )转换 ,在此基础上无新的错义突变发生。p16基因在BEAS 2B细胞和BEAS STE细胞中均为野生型 ,在BEAS TTb细胞中第 4密码子发生TCG→TAG(丝氨酸→终止密码子 )碱基转换 ,结果为无义突变 ,第 19,5 2密码子分别发生GAG→AAG (谷氨酸→赖氨酸 )转换 ,GCG→ACG(丙氨酸→苏氨酸 )转换的错义突变。BEAS TTc细胞中第 19密码子发生GAG→AAG(谷氨酸→赖氨酸 )转换的错义突变 ,而没有可检测的BEAS TTa细胞的mRNA存在。结论　p16基因的突变或表达缺失与恶性转化细胞的成瘤过程相关。     

凝血酶诱发人支气管上皮细胞恶性转化

目的探讨凝血酶对人类支气管上皮细胞的致癌性和转化涉及的相关机制。方法用75nmo·lL-1凝血酶持续刺激人类乳头状瘤-18永生化的人支气管上皮细胞(BEP2D)70d,观察不同代龄细胞的血清抗性、软琼脂克隆形成率,流式细胞术观察细胞周期改变,逆转录-聚合酶链反应检测凝血酶受体-蛋白酶活化受体(PAR1),c-myc和p21~(cip1)基因表达水平,蛋白质免疫印迹检测C-MYC和P21~(cip1)蛋白表达变化,鉴定细胞的恶性转化表型。结果经传代培养,凝血酶处理的第10代BEP2D细胞血清抗性增强,接种效率提高,第20代细胞呈非贴壁依赖性生长,软琼脂克隆形成率升高达(0.461±0.009)%。流式细胞术结果显示,第22代细胞处于S期比例为55.63%。凝血酶转化第25代、第27代细胞PAR1基因、c-myc基因及C-MYC蛋白表达水平上调。相反,p21~(cip1)基因和P21~(cip1)蛋白表达减弱。凝血酶处理的第20代细胞已具有较为稳定的转化表型和细胞生物学特性,可能是具有裸小鼠致瘤型的恶性转化细胞。每升2×104抗凝血酶单位水蛭素能够拮抗凝血酶对BEP2D细胞的恶性转化作用。结论凝血酶对人支气管上皮细胞具有恶性转化作用,c-myc基因转录和蛋白表达活化与p21~(cip1)失活在这一过程中发挥关键作用。     

烟草中甲基亚硝胺吡啶基丁酮诱发人支气管上皮细胞恶性转化的研究

目的研究吸烟致肺癌过程中人类支气管上皮细胞恶变机制,探索一种较快捷的体外研究吸烟致肺癌的途径。方法采用细胞毒性实验确定亚硝胺吡啶基丁酮(NNK)水溶液转化剂量为600μg/ml,应用NNK多次染毒法对人支气管上皮细胞系(16HBE)进行转化,对转化组织和细胞分别进行病理学检查和透射电镜与扫描电镜分析。结果16HBE细胞染毒至第23代,细胞呈恶性形态;可以在软琼脂上形成集落(锚着非依赖性实验为阳性);裸鼠成瘤实验为阳性。对裸鼠成瘤组织进行病理组织学检查,证实为低分化鳞状细胞癌,并取裸鼠成瘤组织原代培养细胞作扫描电镜和透射电镜检查,结果显示为瘤组织培养细胞具有恶性型肿瘤细胞的特征。结论NNK致16HBE细胞恶性转化能力较强,为深入研究人类支气管上皮细胞恶变机制提供了理想的生物模型。     

3-methylindole-induced toxicity to human bronchial epithelial cell lines.

Transfected BEAS-2B cells that express different cytochrome P450 enzymes were used to assess whether human bronchial epithelial cell lines are target cells for 3-methylindole (3MI)-induced damage. Four different transfected BEAS-2B lines overexpressing P450s 2A6, 3A4, 2F1, and 2E1 (B-CMV2A6, B-CMV3A4, B-CMV2F1, and B-CMV2E1), respectively, were compared. The B-CMV2F1 and B-CMV3A4 cells were the most susceptible to 3MI-mediated cytotoxicity, measured by leakage of lactate dehydrogenase into the medium after a 48-h incubation. The toxicity was ameliorated by pretreatment with 1-aminobenzotriazole (ABT). Depletion of glutathione with diethylmaleate decreased the onset and increased the extent of cell death with 3MI. Thus, 3MI is cytotoxic to immortalized bronchial epithelial cells overexpressing 2F1 without concomitant depletion of GSH, but depletion of GSH modestly enhances the cytotoxicity of 3MI to human lung cells. Additional studies clearly demonstrated that a low concentration of 3MI (10 micro M) induced apoptosis in BEAS-2B cells that was measured by DNA fragmentation, and apoptosis was inhibited by the presence of ABT. The B-CMV2F1 cells overexpressing 2F1 demonstrated increased apoptosis (measured by Annexin-V binding) at 24 h with 100 micro M 3MI. Therefore, CYP2F1 in human bronchial epithelial lung cells may bioactivate 3MI to 3-methyleneindolenine, which induces programmed cell death at relatively low concentrations. Human lung cells may be susceptible to this prototypical pneumotoxicant.     

Overexpressed Hsp70 alleviated formaldehyde‐induced apoptosis partly via PI3K/Akt signaling pathway in human bronchial epithelial cells

Formaldehyde (FA) is a ubiquitous environmental pollutant, which can induce apoptosis in lung cell and is related to the pathogenesis of asthma, pneumonia, and chronic obstructive pulmonary disease. Heat shock protein 70 (Hsp70) is an ATP‐dependent molecular chaperone and exhibits an anti‐apoptosis ability in a variety of cells. Previous studies reported that the expression of Hsp70 was induced when organisms were exposed to FA. Whether Hsp70 plays a role in the FA‐induced apoptosis and the involved cell signaling pathway remain largely unknown. In this study, human bronchial epithelial cells with overexpressed Hsp70 and the control were exposed to different concentrations of FA (0, 40, 80, and 160 μmol/L) for 24 hours. Apoptosis and the expression levels of PI3K, Akt, p‐Akt, MEK, p‐MEK, and GLI2 were detected by Annexin‐APC/7AAD double‐labeled flow cytometry and western blot. The results showed that overexpression of Hsp70 decreased the apoptosis induced by FA and alleviated the decline of PI3k and p‐Akt significantly. Inhibitor (LY 294002, a specific inhibitor of PI3K‐Akt) test result indicated that PI3K‐Akt signaling pathway was involved in the inhibition of FA‐induced apoptosis by Hsp70 overexpression and also active in the maintenance of GLI2 level. However, it also suggested that other signaling pathways activated by overexpressed Hsp70 participated in this process, which was needed to be elucidated in further research.     

塞替派诱发人支气管上皮细胞恶性转化过程中的基因突变（二）

目的 观察抗癌药物塞替派诱发永生化人支气管上皮细胞恶性转化过程中相关基因的突变并分析其意义。方法 以塞替派作为致癌原诱导永生化人支气管上皮细胞（BEAS－2B）,获得转化细胞（BEAS－TE）和克隆化多倍体癌前转化细胞（BEAS－STE）。采用PCR－SSCP法检测上述3种细胞p53、p16和Ki-ras 3种基因是否出现点突变,进一步测序确定其突变情况。结果 SSCP结果阳性的有BEAS－TE细胞p53第7外显子,BEAS－STE细胞p53第8外显子以及这二种细胞的p16基因第1外显子;Ki-ras基因第1外显子的结果仅为可疑阳性。测序证明,p53、Ki-ras基因存在多位点的碱基突变,而p16基因仅为单位点的碱基突变。结论 塞替哌可诱发人支气管上皮细胞p53、Ki-ras多位点的碱基突变和p16的单位点突变。分析前者为塞替派诱导细胞转化过程中发生的重要分子事件,后者是次要分子事件。     

Steroid 9alpha-hydroxylation during testosterone degradation by resting rhodococcus equi cells

The conversion pathway of testosterone to androst-4-ene-3,17-dione and 9alpha-hydroxy androstane metabolites, 9alpha-hydroxyandrost-4-ene-3,17-dione and 9alpha,17beta-dihydroxyandrost-4-en-3-one was proposed for the ring degradation in steroids by a minimal liquid medium (NMMP)-dispersed Rhodococcus equi ATCC 14887. The microorganism produced 9alpha-hydroxy androstane metabolites from testosterone at high conversion ratio without the addition of ring degradation inhibitory agents. Several NMMP-based media showed the similar effect on the microbial transformation, in which the respective molar yields of 9alpha-hydroxyandrost-4-ene-3,17-dione and 9alpha,17beta-dihydroxyandrost-4-en-3-one were approx. 3 to 47% and approx. 3 to 11%, respectively, whereas nutrient broth, a rich medium, basically showed no accumulation. On the basis of this evidence, magnesium sulfate and casamino acids among the components of NMMP were found to compromise the determinant for the production of the 9alpha-hydroxy androstane metabolites without appreciable decomposition of the steroid ring system.     

GM3通过MMP-9调节B16细胞的运动性

目的通过不同的方法来研究GM3对MMP-9的调节作用。并进一步验证了GM3对细胞运动性的调节。方法分别用RT-PCR,Zymography,HPTLC,western blotting和transwell的方法来检测MMP-9的mRNA表达水平,MMP-9的活性,GM3,Akt的磷酸化以及细胞的运动性。结果通过几种不同的方法来研究是否GM3参与MMP-9的调空:a.通过转染半乳糖转移酶的顺反序列来调节GM3的表达,从而初步证明GM3可以调节MMP-9的表达;b.通过外加GM3可以清楚的观察到MMP-9的表达量升高;c.神经节苷脂抑制剂D-PDMP的加入更进一步的证明了MMP-9的表达始终与GM3的表达相关;另外,通过PI3K抑制剂的试验进一步证明了GM3通过PI3K来调节MMP-9的表达。在此基础上,更进一步的证明了神经节苷脂可以调节细胞的运动性。结论GM3可以通过PI3K/Akt信号传导途径来正调控MMP-9的表达,并且调节细胞的运动性。