Inhibitory Effects of Parthenolide on the Activity of NF-κB in Multiple Myeloma via Targeting TRAF6

This study examined the mechanism of the inhibitory effect of parthenolide(PTL) on the activity of NF-κB in multiple myeloma(MM). Human multiple myeloma cell line RPMI 8226 cells were treated with or without different concentrations of PTL for various time periods, and then MTT assay was used to detect cell proliferation. Cell cycle and apoptosis were flow cytometrically detected. The level of protein ubiquitination was determined by using immunoprecipitation. Western blotting was employed to measure the level of total protein ubiquitination, the expression of IκB-α in cell plasma and the content of p65 in nucleus. The content of p65 in nucleus before and after PTL treatment was also examined with immunofluorescence. Exposure of RPMI 8226 cells to PTL attenuated the level of ubiquitinated Nemo, increased the expression of IκB-α and reduced the level of p65 in nucleus, finally leading to the decrease of the activity of NF-κB. PTL inhibited cell proliferation, induced apoptosis and blocked cell cycle. Furthermore, the levels of ubiquitinated tumor necrosis factor receptor-associated factor 6(TRAF6) and total proteins were decreased after PTL treatment. By using Autodock software package, we predicted that PTL could bind to TRAF6 directly and tightly. Taken together, our findings suggest that PTL inhibits the activation of NF-κB signaling pathway via directly binding with TRAF6, thereby suppressing MM cell proliferation and inducing apoptosis.     

Autophagy Attenuates MnCl2-induced Apoptosis in Human Bronchial Epithelial Cells

Objective To investigate the role of autophagy in MnCl2-induced apoptosis in human bronchial epithelial 16HBE cells.
Methods Cell proliferation was measured by MTT assay. Mitochondrial membrane potential (MMP) and apoptosis were measured by flow cytometry. Autophagic vacuoles were detected by fluorescence microscopy. Cellular levels of apoptosis and autophagy-related proteins were measured by western blotting.
Results 16HBE cell proliferation was inhibited by MnCl2 in a dose- and time-dependent manner. MnCl2-induced 16HBE cell growth inhibition was related to MMP depolarization prior to the induction of apoptosis. Our data revealed that MnCl2-induced apoptosis in 16HBE cells was mediated by decreased expression of Bcl-2 and increased levels of cleaved caspase-3. It was observed that when we exposed 16HBE cells to MnCl2 in a dose-dependent manner, the formation of autophagic vacuoles and the levels of LC-3B-II were elevated. RNA interference of LC3B in these MnCl2-exposed cells demonstrated that MMP loss and apoptosis were enhanced. Additionally, the pan-caspase inhibitor Z-VAD-FMK increased the cellular levels of Bcl-2 and decreased apoptosis, but did not affect the cellular levels of LC3B in MnCl2-treated 16HBE cells.
Conclusion MnCl2 dose- and time-dependently inhibits 16HBE cell proliferation and induces MMP loss and apoptosis. Autophagy acts in a protective role against MnCl2-induced apoptosis in 16HBE cells.     

Role of liver X receptors alpha agonist on expressions of LPS-induced inflammatory response associated factor IRAK-4 and NF-kappaB in Kupffer cells

Objective： To explore the role of activated liver X receptor α （LXRα） on the expressions of interleukin-1 receptor associated kinase-4 （IRAK-4） and NF-kappaB （NF-κB） in the inflammatory response which induced by LPS in the Kupffer cells and to investigate the possible mechanisms of LXRα negative regulation of inflammatory response. Methods： The Kupffer cells were isolated from male Kunming mice by collagen perfusion in situ. And these cells were divided into 4 groups： normal control group, LPS treatment group, LXRct agonist T0901317 treatment group, LPS and T0901317 combined treatment group. The LPS treatment group were treated with a final concentration of 1 μg/ml LPS in RPMI 1640 and cultured for 6 h, the T0901317 treatment group were treated with a final concentration of 5 μg/ml in RPMI 1640 and cultured for 24 h, and the combined treatment group received pre-culture for 24 h with a final concentration of 1μg/ml T0901317 in RPMI 1640 and then cultured for 6 h with a final concentration of 5 μg/ml LPS in RPMI 1640. All groups were cultured for 30 h. The expression of LXRα, IRAK-4 and NF-κB at mRNA and protein levels were detected by real-time PCR and Western blotting, and the TNF-α and IL-1β levels were detected by ELISA. Results： The levels of LXRα mRNA and protein were highest in T0901317 group, and lowest in LPS group （P〈0.05）. The level of IRAK4 and NF-κB mRNAs and proteins were evidently lower in the Combined-treated group than in LPS group （P〈0.05）. And the level of TNF-α and IL-1 were observed highest in LPS group （P〈0.05）, but no difference among the Control group, T0901317 group and Combined-treated group （P〉0.05）. Conclusion： These date suggest that the LXR agonists can effectively up-regulate the expressions of LXRα mRNA and protein and inhibit the inflammatory response. This may be via down-regulating the expressions of IRAK4 and NF-κB at mRNA and protein levels.     

Matrine and CYC116 Synergistically Inhibit Growth and Induce Apoptosis in Multiple Myeloma Cells

Objective:To investigate whether CYC116 can potentiate matdne-dependent growth inhibition and apoptosis in multiple myeloma(MM)cells.Methods:The dose response relationship of matrine to dexamethasone-resistant and dexamethasone-sensitive MM cells was first established.Myeloma RPMI8226cells were treated with matrine alone or combined with CYC116 for 24 h.Cell proliferation was measured using an MTT-T assay and apoptosis induction was evaluated by flow cytometry.Activation of the caspase pathway and expression of apoptosis regulator proteins were detected by Western blotting.Results:Matrine significantly induced growth arrest and apoptosis in both drug-resistant and drug-sensitive MM cells.Treatment with the combination of matrine and CYC116 had a stronger cytotoxic effect on MM cells than did single drug treatments.Enhanced apoptosis observed following the combined treatment of matrine and CYC116 was associated with higher levels of activation of caspase-9,caspase-3,and poly adenosine diphosphate ribose polymerase(PARP)and down-regulation of the anti-apoptotic proteins Bcl-2 and Mcl-1 and the signaling proteins p-Akt and nuclear factorκB(NF-κB).Conclusions:CYC116 enhances the growth inhibitory and apoptotic effects of matdne on MM cells.     

Different apoptotic reactions of dorsal root ganglion A- and B-cells after sciatic nerve axotomy: effect of p75 neurotrophin receptor

Background By unbiased stereological methods, we have observed preferential dorsal root ganglion （DRG） B-cell loss in rodents after nerve injury, and caspase-3 activation and cell loss were related to the present of p75 receptor （p75^NTR）. We hypothesized that DRG B-cells express higher levels of pro-apoptotic proteins as compared to A-cells and the expressions of pro-apoptotic proteins can be reduced by depletion of p75^NTR. This study aimed to identify the p75NTR involved apoptotic pathway in DRG neurons after nerve injury. Methods The p75NTR knockout mice （p75-/-） and wildtype Balb/C mice （p75＋/＋） were used in this study. The expressions of pro-apoptotic proteins, c-Jun-N-terminal kinase （JNK）, c-jun and p38 in DRG were evaluated with immunohistochemistry 2 and 7 days following unilateral sciatic nerve transection. In addition, extra-cellular related kinase （ERK）, a transducer of survival signals, was also tested with immunohistochemistry and Western blotting methods in these animal models. Results Phosphorylated JNK （P-JNK） and phosphorylated p38 （P-p38） were mainly located in small B-cells, whereas phosphorylated c-jun （P-c-jun） was located in both A- and B-cells. Phosphorylated ERK （P-ERK） was located in both B-cells and satellite cells. Axotomy dramatically increased the expressions of P-JNK and P-c-jun （paired t-test）, with no influence on the expressions of P-p38 and P-ERK. Furthermore, the increase of P-JNK in p75＋/＋ mice 2 days after nerve axotomy was approximately 2.2-folds of that in p75-/- mice （P=-0.001, unpaired t-test）. Conclusion p75NTR-dependent JNK-caspase-3 pathway is involved in DRG B-cell loss after nerve injury and JNK is not the unique upstream of c-jun activation.     

Differential activation of mitogen—activated protein kinases by γ—irradiation in IEC—6 cells：Role of intracelluklar Ca^2＋

Abstract Objective:To explore the effects of γ-irradiation on mitogen-activatedprotein kinases(MAPKs) and role intracellular calcium in this event in intestinal epithelial cell line 6(IEC-6 cells).Methods:After cultured rat IIEC-6 cells with or without the pretreatment of intracellular Ca^2 chelator were exposed to γ-ir-radiation of 6 Gy, the total and phosphorylated MAPKs in the cells were determined with Western blotting and apoptosis was examined with flow cytometry.Activities of Extracellular signal-regulated protein kinase (ERK) and p38 MAPK were determined by using immuoprecipitation followed by Western blotting.Results:In response to γ-irradiation,phosphorylation of ERK was not significantly observed ,while the levels of phos-phorylated c-Jun NH2-terminal kinase(JNK) and p38 MAPK were increased in 30 min and reached the peak 2h after exposure to 6Gy γ-irradiation,though the cell viability was significantly lowered 12h.On the other hand, no obvious changes were seen in the total protein levels of ERK, JNK and p38 MAPK.Chelation of in-tracellular Ca^2 almost completely suppressed the JNK and p38 MAPK phosphorylation induced by γ-irradiation is a potent activator for JNK and p38 MAPK, and Ca^2 mobilized from intracellular stores plays an important role in the activation of MAPKs and the induction of apoptosis in IEC-6 cells.     

Triptolide-induced apoptosis by inactivating nuclear factor-kappa B apoptotic pathway in multiple myeloma <Emphasis Type="Italic">in vitro</Emphasis>

The effect of triptolide on proliferation and apoptosis of human multiple myeloma RPMI-8226 cells in vitro,as well as the roles of nuclear factor-kappa B(NF-κB) and IκBα was investigated.The effect of tritptolide on the growth of RPMI-8226 cells was studied by MTT assay.Apoptosis was detected by Hoechest 33258 staining and Annexin V/PI double staining assay.The expression of NF-κB and IκBα was observed by Western blot and confocal microscopy.The results showed that triptolide inactivated NF-κB apoptotic pathway in human multiple myeloma RPMI-8226 cells.Triptolide at nM range induced proliferation inhibition in a dose-and time-dependent manner and apoptosis in a dose-dependent fashion in RPMI-8226 cells.Besides,we observed the inhibition of NF-κB /p65 in the nuclear fraction was correlated with the increase in the protein expression of IκBα in the cytosol.These results suggested that triptolide might exhibit its strong anti-tumor effects via inactivation of NF-κB/p65 and IκBα.     

Effects of Human Cytomegalovirus Infection on Apoptosis and Expression of Apoptosis-Regulating Factors

Summary： The present study aimed to find out dynamic changes of apoptosis in human cytomegalovirus （HCMV） infected cells and the influence of HCMV infection on activation of caspase-3 and the expression of apoptosis-regulating genes, bcl-2 and fas mRNA. The sequential changes of apoptotic cell rate in high and low MOI （MOI=2.5 and 0.25 respectively） of HCMV infected human embryonic lung fibroblasts （HELFs） at 1 h, 12 h, 24 h, 36 h, 48 h, 72 h and 96 h post-infection were measured by flow cytometry. The expression levels of caspase-3 protein and bcl-2 and fas mRNA in HCMV infected cells （MOI=0.25） at 72 h post-infection were detected by Western blot and in situ hybridization methods, respectively. It was found that the ratio of apoptotic cells in normal controls was consistently lower, but the rates in low and high MOI infected cells were gradually increased with time prolonged, reached peak at 96 h （8.85 %） and 72 h （25.63 %）, respectively. By Western blot analysis, only a narrow band of 32 kD （1 kD=0. 992 1 ku） procaspase-3 was found in normal cells, but a wider procaspase-3 band and a much wider band of 17 kD proteins （p17） ap- peared in the infected cells. Meanwhile, the expression of bcl-2 mRNA was higher and that of fas mRNA was lower in the normal HELF cells, whereas there were significantly lower bcl-2 mRNA and higher fas mRNA expression levels in HCMV infected cells. It was concluded that HCMV was a stronger inducer of apoptosis in HELF cells. Caspase-3, as the marker of undergoing apoptosis, was expressed increasingly and activated in the infected cells, indicating its action in HCMV-inducing apoptosis. Down-regulating bcl-2 mRNA expression and up-regulating fas mRNA expression were also involved in the mechanism of HCMV-induced apoptosis.     

Mitogen-activated protein kinase-dependent apoptosis in norcan-tharidin-treated A375-S2 cells is proceeded by the activation of protein kinase C

Background We have reported that norcantharidin (NCTD) induces human melanoma A375-S2 cell apoptosis and that the activation of caspase and the mitochondrial pathway are involved in the apoptotic process. This study aimed at investigating the roles of mitogen-activated protein kinase (MAPK) and protein kinase C (PKC) in A375-S2 cell apoptosis induced by NCTD.Methods We assessed the effects of NCTD on cell growth inhibition using the 3-(4,5-dimethyhhiazol-2-yl)-2,5-dipheyhetrazolium bromide (MTT) assay, DNA fragmentation (DNA agarose gel electrophoresis), and MAPK protein levels (Western blot analysis) in A375-S2 cells. Photomicroscopic data were also collected.Results The NCTD inhibitory effect on A375-S2 cells was partially reversed by MAPK and PKC inhibitors.The expression of phosphorylated JNK and p38 also increased after the treatment with NCTD, and inhibitors of c-Jun NH2 -terminal kinase (JNK) and p38 (SP600125 and SB203580, respectively) had significant inhibitory effects on the upregulation of phosphorylated JNK and p38 expression. Simultaneously, the PKC inhibitor staurosporine blocked the upregulation of phosphorylated JNK and phosphorylated p38, but had little effect on extracellular signal-regulated kinase (ERK) expression.Conclusion These results suggest that the activation of JNK and p38 MAPK promotes the process of NCTDinduced A375-S2 cell apoptosis and that PKC plays an important regulation role in the activation of MAPKs.     

三氧化二砷诱导人骨髓瘤细胞RPMI8226自噬及凋亡关系的研究

目的通过引入自噬及凋亡抑制剂观察三氧化二砷（As2O3）作用于骨髓瘤细胞RPMI 8226引起自噬和凋亡之间的关系。方法①MTT法计算细胞生长抑制率。②流式细胞仪检测RPMI 8226细胞的自噬率及凋亡率的变化。③通过Western Blot方法检测不同实验组Beclin-1及Caspase-3表达的变化。结果①各浓度As2O3对人骨髓瘤细胞RPMI 8226都显示出明显的生长抑制作用（P〈0.05）,且呈时间-剂量依赖性。②与As2O3单独处理组相比,3-MA预处理组,As2O3诱导RPMI 8226细胞凋亡率呈下降趋势,有统计学意义（P〈0.05）;zVAD-fmk与As2O3联合处理组,凋亡率未见明显变化（P〉0.05）。与As2O3单独处理组相比,3-MA预处理组,As2O3诱导RPMI 8226细胞自噬率下降,有统计学意义（P〈0.05）;zVAD-fmk与As2O3联合处理组As2O3诱导RP-MI8226细胞自噬率亦下降,有统计学意义（P〈0.05）。③与As2O3单独加药组比较,3-MA预处理组As2O3诱导RPMI 8226细胞Procaspase-3蛋白表达明显升高,Beclin-1表达下降;zVAD-fmk预处理组亦表现为Procaspase-3蛋白表达明显升高,Beclin-1下降。结论①不同浓度组As2O3作用24、48、72h对RPMI8226细胞的增殖均有明显的抑制作用（P〈0.05）,且该作用成时间-剂量依赖关系。②As2O3可诱导RPMI 8226细胞发生凋亡及自噬,两者的关系表现为互为前提。抑制任何一方都会导致另一方过程受抑。③As2O3诱导RPMI 8226细胞凋亡过程中可能存在Caspase非依赖型细胞凋亡程序。     

p53在漆树黄酮诱导人肝癌细胞系HepG2细胞凋亡的作用

目的:观察漆树黄酮诱导人肝癌细胞系HepG2细胞凋亡的现象,研究p53在漆树黄酮诱导人肝癌细胞系HepG2细胞凋亡的作用究。方法：用不同浓度的漆树黄酮（50μmol•L-1、100μmol•L-1、200μmol•L-1）处理HepG2细胞24h和100μmol•L-1漆树黄酮处理HepG2细胞不同时间（12h、24h、48h）,流式细胞术和免疫荧光法观察漆树黄酮作用HepG2细胞的凋亡情况; Westem blot法检测漆树黄酮对HepG2细胞p53、Caspase-3 和Caspase-8蛋白的表达情况。结果:漆树黄酮能诱导HepG2细胞凋亡,呈剂量一时间依赖性; 漆树黄酮可增加p53蛋白的表达,降解Caspase-3 、Caspase-8酶原,提高Caspase-3 、Caspase-8活性。p53蛋白的上调与凋亡的发生呈正相关,Caspase-3 、Caspase-8酶原的降解与与凋亡的发生呈负相关。结论:漆树黄酮可诱导HepG2细胞凋亡,其机制可能与上调p53表达,活化Caspase-3、 Caspase-8有关。     

5-氮-2′-脱氧胞苷对RPMI8226细胞增殖、凋亡及SOCS-1基因表达的影响

目的  研究DNA甲基转移酶抑制剂5-杂氮-2'-脱氧胞苷(5-Aza-CdR)对人多发性骨髓瘤细胞株RPMI8226生物学活性以及SOCS-1基因表达的影响。 方法  不同浓度5-Aza-CdR（0.1、0.5、1.0、2.0、5.0μmol/L）对RPMI8226细胞干预后,采用MTT法检测细胞增殖活性;流式细胞术分析细胞凋亡及细胞周期的改变;Real-time PCR法检测各组细胞SOCS-1 mRNA的表达。结果  5-Aza CdR对RPMI8226细胞的生长抑制有明显的时间和剂量依赖性（P<0.05）;流式检测结果显示,0.1、0.5、1.0、2.0、5.0μmol/L 5-Aza-CdR作用于RPMI8226细胞72h后,细胞凋亡率分别为（29.62±2.87）%、（39.98±2.53）%、（49.07±3.51）%、（60.15±4.54）%和（69.88±3.49）%,且呈剂量依赖性（P<0.05）;与对照组相比,5-Aza-CdR处理RPMI8226细胞72h后,细胞阻滞于G0/G1期;Real-time PCR结果显示,SOCS 1基因在RPMI8226细胞中微弱表达,5-Aza-CdR作用后,SOCS-1 mRNA表达水平呈剂量依赖性逐渐升高（P<0.05）。结论  5-Aza-CdR显著抑制多发性骨髓瘤细胞RPMI8226增殖,可能与诱导SOCS-1 基因去甲基化和SOCS-1再表达有关。     

雄黄对多发性骨髓瘤细胞株RPMI 8226细胞基因表达谱的作用

目的：应用cDNA芯片研究雄黄作用多发性骨髓瘤细胞株RPMI8226细胞后对其基因表达的影响。方法：应用包含4096条人类基因的cDNA表达谱芯片，检测雄黄作用于RPMI8226细胞前及48h后基因的表达。结果：在mRNA水平上，164条基因显著改变，53条基因上调，111条基因下调。结论：雄黄作用RPMI8226细胞株后可引起一系列基因改变，许多基因涉及了多发性骨髓瘤的发病机制，其中BTG1，TXNIP及ALK1基因可能与RPMI8226细胞的分化和凋亡有密切关系。     

JNK介导p53的表达在大鼠脑创伤中对神经元自噬的影响

脑创伤后与神经元凋亡和自噬相关的JNK (c-Jun NH2-terminal kinase)通路激活是对各种刺激的反应。但是这个通路的分子途径目前还不清楚。本实验研究JNK介导p53磷酸化,依次提高了靶基因DRAM的表达和Beclin-1的表达,但同时也使Beclin-1与bcl-2和/或bcl-xl的复合物表达降低。DRAM和Beclin-1的表达升高可以提高自噬,这也说明了脑创伤后JNK介导p53磷酸化是提高神经元自噬的重要机制,同时本试验应用的JNK抑制剂SP600125在干预组明显抑制了脑外伤引起的因子的变化和脑组织形态结构的改变。     

基于PI3K/AKT/mTOR探索硼替佐米对多发性骨髓瘤侧群细胞的作用机制

目的 探讨26S蛋白酶体抑制剂硼替佐米对多发性骨髓瘤细胞系RPMI8226和骨髓瘤侧群(side population,SP)细胞的作用机制及其耐药性。 方法 在RPMI8226和SP细胞增殖以及生长周期和凋亡差异性研究基础上,采用Western blotting方法检测硼替佐米对2种细胞内信号通路PI3K/AKT/mTOR磷酸化水平的影响;通过硼替佐米耐药性研究,开展RPMI8226和SP细胞对硼替佐米耐药机制的探索。 结果 SP细胞48 h相对细胞活力(3.62±0.28)显著高于RPMI8226细胞(2.81±0.24,P=0.028);克隆形成能力结果显示SP细胞显著强于RPMI8226细胞(P<0.05)。流式细胞术检测显示硼替佐米增加了2种细胞S期、降低G₂/M期,对RPMI8226的促凋亡率(51.23±5.35)显著高于SP细胞凋亡率(29.62±2.61,P=0.008)。Western blotting结果显示硼替佐米显著降低RPMI8226和SP细胞AKT、mTOR及4E-RP1磷酸化水平;耐药性结果显示SP细胞耐药相关蛋白P-gp、Caveolin-1(Cav-1)、Fatty acid synthase(FASN)及CYP3A4表达显著高于RPMI8226细胞。 结论 硼替佐米主要通过细胞凋亡和降低PI3K/AKT/mTOR信号蛋白磷酸化水平,发挥对RPMI8226和SP细胞的抑制作用;通过P-gp、Cav-1、FASN以及CYP3A4耐药蛋白发挥对多发性骨髓瘤的耐药性。      

尿多酸肽（CDA-2）诱导多发性骨髓瘤细胞RPMI8226凋亡的实验研究

[目的]观察尿多酸肽（CDA-2）对多发性骨髓瘤细胞RPMI8226抑制增殖和凋亡作用。[方法]应用MTT法,检测CDA-2对多发性骨髓瘤细胞株RPMI8226增殖的影响。通过Hochest33258染色、流式细胞仪（AnnexinV和PI双染色）检测细胞凋亡。[结果]CDA-2明显抑制RPM18226细胞的增殖。CDA-2作用RPM18226细胞增殖24h的半数抑制浓度（IC50）分别为1.64mg/g。采用Hochest33258染色,荧光显微镜下观察CDA-2以2mg/g及4mg/g终浓度作用于RPM1822624h后细胞形态改变,可见明显的凋亡小体出现。AnnexinV-PI双标记法流式细胞仪分析结果显示,RPMI8226细胞2mg/gCDA-2作用6、12、24h后,早期凋亡细胞百分数分别为5.43%、12.02%、29.07%,明显高于空白对照组4.88%。[结论]CDA-2对MM细胞株RP-MI8226有生长抑制作用,可能是通过诱导其发生凋亡而起作用。     

DJ-1对MPP+诱导的多巴胺能神经元损伤的保护机制研究

目的 探讨DJ-1基因对MPP+诱导的多巴胺能神经元损伤模型的保护机制.方法 用神经生长因子(NGF)将PC12诱导成神经元样分化的细胞株(多巴胺能神经元).用1-甲基-4苯基吡啶离子(MPP+)诱导帕金森病PC12细胞损伤模型,用CCK-8试剂盒检测细胞增殖活性,DHE染色法检测ROS水平变化.Western blot检测DJ-1和TH蛋白表达变化,RT-qPCR检测α-synuclein和凋亡相关基因的RNA水平.用pCDH1-cmv载体过表达DJ-1后检测DJ-1对MPP+环境中细胞的保护作用.用RT-qPCR检测α-synuclein、p53和Bax的表达变化.结果 160μmol/L的MPP+处理18 h后,PC12细胞活性降低,细胞内ROS水平升高,处理48 h后细胞凋亡增加.DJ-1和TH蛋白表达均明显下调,RNA水平上α-synuclein、p53和Bax表达增加.过表达DJ-1能够保护MPP+中的细胞活性,抑制ROS水平升高.α-synuclein以及凋亡基因p53和Bax的表达升高受到抑制,细胞凋亡减少.结论 MPP+作用于多巴胺神经元,可以下调DJ-1和TH蛋白,促进α-synuclein积累ROS水平升高,并使p53和Bax表达增加,导致细胞凋亡增加.DJ-1基因能够能够在MPP+处理时抑制p53和Bax的表达,减少α-synuclein积累,降低细胞内ROS水平,保护细胞免受MPP+引起的损伤.     

H3K27me3聚集MEG3 lncRNA启动子通过MDM2/p53途径诱导多发性骨髓瘤RPMI8226细胞凋亡逃逸

目的 从组蛋白甲基化与长链非编码 RNA ( ln-cRNA)相互作用角度探讨多发性骨髓瘤( MM)细胞凋亡逃逸的具体机制.方法 MTT法检测细胞增殖活性;Annex-inV-FITC/PI双标流式细胞术检测下调组蛋白H3第27位赖氨酸上三甲基化H3K27me3 的表达是否可以诱导多发性骨髓瘤细胞株—RPMI8226 细胞凋亡; RT-PCR 法检测 RP-MI8226细胞中人母系表达基因( MEG3) lncRNA及鼠双微体基因 2 ( MDM2 )的 mRNA 表达; Western blot 检测 RP-MI8226 细胞中 Zeste 基因增强子同源物 2 ( EZH2 )、H3K27me3、MDM2 及 p53 蛋白表达; ChIP Real -time PCR检测RPMI8226细胞中 H3K27me3 的结合位点.结果 在RPMI8226 细胞中,下调 H3K27me3 可诱导细胞凋亡;H3K27me3可直接结合于 MEG3lncRNA 启动子; RPMI8226细胞中抑制了 H3K27me3 可上调 MEG3lncRNA 表达; RP-MI8226经MEG3lncRNA 小干扰 RNA ( MEG3lncRNA -siR-NA)干预下调MEG3lncRNA时,细胞内MDM2 mRNA水平明显升高,并诱导 MDM2 蛋白表达.给予 MDM2 拮抗剂后, Ub-p53 表达降低, p53 降解被抑制.结论 MM 中H3K27me3结合MEG3 lncRNA启动子,MEG3lncRNA启动子H3K27me3高表达导致MEG3 lncRNA表达缺失. MEG3 ln-cRNA表达缺失解除MDM2的抑制, MDM2与p53直接结合介导p53泛素化,促使p53降解,细胞凋亡逃逸.