丝裂原活化蛋白激酶通路正性调节苯并(a)芘所致细胞周期改变

目的 研究苯并（a）芘（BaP）对人胚肺成纤维细胞（HELF）的细胞周期分布及丝裂原活化蛋白激酶（MAPK）信号分子（ERK1／2、JNK1／2和p38）磷酸化水平的影响,并探讨MAPK磷酸化水平改变与细胞周期效应之间的关系。方法 用0．1、0．5、2．5和12．5μmol／L的BaP处理HELF细胞24h,用蛋白印迹方法检测ERK1／2、JNK1／2和p38蛋白激酶的磷酸化水平和蛋白总量的改变,利用流式细胞技术检测2．5μmol／LBaP处理24h后对HELF细胞周期的影响。结果 不同剂量BaP可明显提高ERK1／2、JNK1／2和p38蛋白激酶磷酸化水平;2．5μmol／LBaP处理24h,细胞周期分布与二甲基亚砜对照组相比,G0与G1期细胞数下降了11．9％（F=41．38,P〈0．01）,S期细胞数增加了17．2％（F=68．13,P〈0．01）;三种MAPK化学抑制剂（AG126、SP600125及SB203580）可明显抑制BaP处理引起的细胞周期的改变。结论 ERK1／2、JNK1／2和p38均参与了BaP所致细胞周期改变过程．并发挥币性调节作用。     

ERK和JNK/活化蛋白-1通路在苯并(a)芘诱导人胚肺成纤维细胞周期改变中的作用

目的探讨丝裂原活化蛋白激酶(MAPK)/转录因子活化蛋白-1(AP-1)信号通路在调控苯并(a)芘[B(a)P]致人胚肺成纤维细胞(HELF)周期改变中的作用。方法用AP-1荧光素酶报告基因技术检测AP-1荧光素酶活力,流式细胞术测定细胞周期时相分布,免疫印迹法检测MAPK[包括细胞外调节蛋白激酶(ERK)、c-Jun氨基末端激酶(JNK)和p38激酶]总量及磷酸化水平,用MAPK显性失活突变体(DN)(DN-ERK2、DN-JNK1和DN-p38)证明通路的上下游关系。结果2μmol/L B(a)P分别处理细胞0、6、122、4 h,AP-1活力在12 h达峰值,是对照组的2.22倍,差异有统计学意义(P<0.05);ERK1/2、JNK1/2和p38蛋白激酶的磷酸化水平明显提高,分别是对照组的2.5、14.0和2.1倍;B(a)P处理组S期细胞比例(50.2%±4.6%)与对照组(16.7%±8.1%)相比明显增加,差异有统计学意义(P<0.01);ERK2和JNK1显性失活突变体的过表达均可明显降低B(a)P诱导的AP-1活力增强,并且明显降低B(a)P处理组S期细胞比例(分别为33.3%±1.7%,30.8%±3.9%),差异均有统计学意义(P<0.05);p38显性失活突变体的过表达对B(a)P引起的AP-1活力增强及S期细胞比例增加无影响。AP-1化学抑制剂姜黄素(20μmol/L)可明显降低B(a)P引起的S期细胞比例增加(13.6%±2.9%),差异均有统计学意义(P<0.05)。结论ERK和JNK通过活化AP-1介导B(a)P诱导的细胞周期改变;而B(a)P诱导的AP-1活力增强及细胞周期改变与p38无关。     

电离辐射联合自噬诱导剂或抑制剂对人宫颈癌Hela细胞的作用

目的 探讨电离辐射联合自噬抑制剂或诱导剂对人宫颈癌细胞株增殖的影响。方法 采用四甲基偶氮唑蓝(MTT)和流式细胞术(FCM)检测经不同剂量(0、2、4、6、8和10 Gy)照射和6 Gy+自噬抑制剂三甲基腺嘌呤(3-MA)及6Gy+自噬诱导剂雷帕霉素(rapamycin)不同方法处理的人宫颈癌细胞存活和增殖情况,并分析其量效和时效关系。结果 随着照射剂量的增加(2、4、6、8和10 Gy)及时间的延长(24、48和72 h),宫颈癌细胞增殖的抑制作用组间比较差异有统计学意义(P<0.05或P<0.01)。6 Gy+rapamycin处理对癌细胞增殖的抑制率低于单纯6Gy照射组(P<0.05),组间比较差异有统计学意义(P<0.05或P<0.01)。6 Gy+3-MA处理对癌细胞增殖的抑制高于单纯6 Gy照射组(P<0.05),处理后24、48和72 h其抑制率组间比较差异有统计学意义(P<0.05或P<0.01)。结论 在Hela细胞中电离辐射诱导自噬能够拮抗凋亡,电离辐射联合自噬诱导剂能够抑制Hela细胞凋亡,而电离辐射联合自噬抑制剂能够促进其凋亡。     

Ku80/p53通路在石英诱导的细胞周期改变中的作用

目的 探讨在石英刺激的人胚肺成纤维细胞(human embryo lung fibroblasts,HELF)中Ku80蛋白表达的变化及Ku80/p53通路在石英诱导的细胞周期改变中的作用.方法 RNAi技术抑制Ku80蛋白表达,流式细胞技术检测细胞周期,免疫印迹技术检测Ku80、p53、p21蛋白的表达及p53-ser15磷酸化水平,并用Image-Pro plus 6.0软件对条带光强度进行半定量分析.结果 Ku80蛋白表达与石英刺激呈剂量-反应和时间-反应关系;石英刺激阴性对照H-NC细胞,G1期细胞所占比例从89.28%±2.19%下降到68.93%±3.79%;抑制Ku80蛋白表达的HELF细胞(H-Ku80)的G1期细胞所占比例进一步减少,从85.16%±3.73%下降到59.92%±3131%,差异均有统计学意义(P<0.05);抑制Ku80蛋白表达后,石英引起的p53、p21蛋白及p53-ser15磷酸化水平增高受抑制.结论 Ku80对p53、p21蛋白表达及p53-ser15磷酸化水平起调节作用,Ku80/p53通路可能参与了石英诱导的细胞周期改变.

Abstract：

Objective To study the roles of Ku80/p53 pathway in silica-induced cell cycle changes in human embryo lung fibroblasts (HELF). Methods Ku80 siRNA expression vectors were transfected into HELF by lipofectamine. Flow cytometry was used to detect the distributions of cell cycle and western blot assay was used to determine the expression level of Ku80, p53 and p21 proteins or the phosphorylation levels of p53-serl5 after cells were exposed to silica. Results The expression levels of Ku80 protein increased in concentration-dependent and time-dependent manners after cells were exposed to silica. The proportion of G1 phases in H-NC cells (controls) decreased from 89.28%±2.19% to 68.93%±3.79% after exposure to silica, and the proportion of G1 phases in HELF cells (H-Ku80) decreased from 85.16%±3.73% to 59.92%±3.31% after exposure to silica (P<0.05). The expression levels of Ku80, p53 protecns or p21 proteins or phosphorylation level of p53-serl5 were obviously suppressed in H-Ku80, as compared with H-NC. Conclusion Ku80/p53 pathway plays a role in the cell cycle charges induced by silica in human embryo lung fibroblasts.     

Cell culture condition-dependent impact of AGE-rich food extracts on kinase activation and cell survival on human fibroblasts

Advanced glycation end products (AGEs) are stable end products of the Maillard reaction. Effects of food extracts are often initially analysed in cellular test systems and it is not clear how different cell culture conditions might influence the results. Therefore, we compared the effects of two models for AGE-rich food, bread crust and coffee extract (CE) on WI-38 human lung fibroblasts under different cell culture conditions (sub-confluent versus confluent cells, with and without serum). WI-38 cells responded to coffee and bread crust extract (BCE) with a rapid phosphorylation of PKB (AKT), p42/44 MAPK (ERK 1/2) and p38 MAPK, strongly depending on culture conditions. BCE resulted in increased cell numbers, whereas CE appeared to be cytotoxic. When cell numbers under all culture conditions and treatments were correlated with kinase phosphorylation, the relation between phospho-p38 MAPK and phospho-AKT represented a good, cell culture condition-independent predictor of cell survival.     

The low-dose ionizing radiation stimulates cell proliferation via activation of the MAPK/ERK pathway in rat cultured mesenchymal stem cells

Hormesis induced by low-dose ionizing radiation (LDIR) is often mirrored by its stimulation of cell proliferation. The mitogen-activated protein kinases (MAPK)/ extracellular-signal- regulated kinases (ERK) pathway is known to play important roles in cell growth. Therefore, this study was to examine the effects of LDIR on rat mesenchymal stem cell (MSC) proliferation and MAPK/ERK signaling pathway. Rat MSCs were isolated from the bone marrow from 6 to 8-week-old male Wistar rats and cultured in vitro. Exponentially growing cells within 4-5 passages were irradiated with low doses of X-rays at 20, 50, 75 and 100 mGy with a dose rate of 100 mGy/min. Cell proliferation was evaluated by counting total viable cell number with trypan-blue staining and MTT assay. Cell cycle changes were also evaluated by flow cytometry and the activation of MAPK/ERK signaling pathway was assayed by Western blotting. Results showed that LDIR at 50 and 75 mGy significantly stimulated the proliferation of rat MSCs with the most stimulating effect at 75 mGy. There was a significant increase in the proportion of S phase cells in MSCs in response to 75 mGy X-rays. Activation of several members in the MAPK/ERK signaling pathway, including c-Raf, MEK and ERK were observed in the cells exposed to 75 mGy X-rays. To define the role of ERK activation in LDIR-stimulated cell proliferation, LDIR-treated MSCs were pre-incubated with MEK specific inhibitor U0126, which completely abolished LDIR-increased phosphorylation of ERK and cell proliferation. These results suggest that LDIR stimulates MSC proliferations in the in vitro condition via the activation of MAPK/ERK pathway.     

Genistein activates p38 mitogen-activated protein kinase,inactivates ERK1/ERK2 and decreases Cdc25C expression in immortalized human mammary epithelial cells

Genistein (4',5,7-trihydroxyisoflavone) is an isoflavonoid present in soybeans that exhibits anticarcinogenic effects in breast, colon and prostate cancer cells. We recently reported that genistein treatment of the immortalized but nonmalignant human mammary epithelial cell line MCF-10F resulted in growth arrest of MCF-10F cells in the G2 phase of the cell cycle, a large induction of the Tyr15 phosphorylation of Cdc2 (along with decreased activity of Cdc2), increased expression of p21(waf/cip1) and decreased expression of the cell cycle phosphatase Cdc25C. In the present study of MCF-10F cells, genistein rapidly and significantly activated p38, inactivated ERK1/ERK2 and had no effect on SAPK/JNK activity. We also showed that p38 is involved in genistein-induced changes in Cdc2 phosphorylation and that the downregulation of Cdc25C expression by genistein is through the p38 pathway. Finally, we provided evidence that the p38 pathway is involved in genistein-inhibited cell proliferation. These data suggest an important interplay between the p38 pathway and G2 cell cycle checkpoint control and provide insights into possible mechanisms whereby this isoflavone may inhibit early events in mammary carcinogenesis.     

Pretreatment with rituximab enhances radiosensitivity of non-Hodgkin's lymphoma cells

The present study examines the effects of ionizing radiation in combination with rituximab (RTX), a chimeric human anti-CD20 monoclonal antibody, on proliferation, cell cycle distribution and apoptosis in B-lymphoma RL and Raji cells. Exposure to ionizing radiation (9 Gy) induced cell growth delay and apoptosis in RL cells, whereas Raji cells showed moderate radio-resistance. The simultaneous exposure of lymphoma cells to ionizing radiation and RTX (10 microg/mL) markedly enhanced apoptosis and cell growth delay in RL and Raji cells. Cooperative antiproliferative and apoptotic effects of RTX and radiation were achieved through the inhibition of c-myc and bcl-XL expression. Furthermore, RTX-modulated expression of cell cycle regulating proteins, such as p53, p21/WAF1, p27/KIP1, contributed to the development of radiation-induced cell killing and growth arrest. Each NHL cell line that underwent apoptosis induced by combination treatment revealed enhanced caspase-3 and poly (ADP-ribose) polymerase (PARP) cleavage as compared to only irradiated cells. These findings show that rituximab synergistically enhances radiation-induced apoptosis and cell growth delay through the expression of proteins involved in the programmed cell death and cell cycle regulation pathways.     

转化生长因子β1和丝裂原活化激酶通路调控人肺成纤维细胞表型

目的　探讨丝裂原活化蛋白激酶(MAPK)在转化生长因子β1(TGF β1)诱导人肺成纤维细胞表型分化中的作用。方法　以人肺成纤维细胞HLF 0 2细胞系为研究对象,给予10ng/mlTGF β1刺激不同时间;阻断实验以SB2 0 35 80、PD980 5 9分别阻断p38通路和细胞外调控激酶(Erk)通路;采用逆转录-聚合酶链反应(RT PCR)检测细胞内表型分化标志物α-平滑肌肌动蛋白(αSMA)mRNA的表达;运用Western印迹检测细胞内p38、Erk、c jun氨基末端激酶(JNK)磷酸化以及αSMA蛋白表达的强度。结果　(1)TGF β1刺激HLF 0 2细胞2 4h组、4 8h组、72h组的αSMAmRNA表达水平分别为:1.87±0 .11、2 .4 9±0 .10、3.0 2±0 .15 ;αSMA蛋白表达水平分别为:3.2 0±0 .14、3.96±0 .2 1、4 .5 7±0 .13。(2 )TGF β1可以激活HLF 0 2细胞内p38和Erk通路,对JNK没有活化作用。(3)SB2 0 35 80、PD980 5 9各自抑制了TGF β1诱导的p38、Erk激酶的磷酸化。(4)SB2 0 35 80抑制了TGF β1诱导的αSMAmRNA和蛋白表达(抑制率分别为30 %和4 0 % ) ;PD980 5 9同样抑制了TGF β1诱导的αSMAmRNA和蛋白表达(抑制率分别为10 %和2 0 % )。结论　TGF β1可诱导HLF 0 2细胞表型的分化,p38、Erk激酶参与了调控TGF β1的促表型分化作用     

Analysis of the cellular stress response in MCF10A cells exposed to combined radio frequency radiation

Exposure to environmental stressors can be measured by monitoring the cellular stress response in target cells. Here, we used the cellular stress response to investigate whether single or combined radio frequency (RF) radiation could induce stress response in human cells. Cellular stress responses in MCF10A human breast epithelial cells were characterized after exposure to 4 h of RF radiation [code division multiple access (CDMA) or CDMA plus wideband CDMA (WCDMA)] or 2 h RF radiation on 3 consecutive days. Specific absorption rate (SAR) was 4.0 W/kg for CDMA signal alone exposure and 2.0 W/kg each, 4.0 W/kg in total for combined CDMA plus WCDMA signals. Expression levels and phosphorylation states of specific heat shock proteins (HSPs) and mitogen-activated protein kinases (MAPKs) were analyzed by Western blot. It was found that HSP27 and ERK1/2 phosphorylations are the most sensitive markers of the stress response in MCF10A cells exposed to heat shock or ionizing radiation. Using these markers, we demonstrated that neither one-time nor repeated single (CDMA alone) or combined (CDMA plus WCDMA) RF radiation exposure significantly altered HSP27 and ERK1/2 phosphorylations in MCF10A cells (p > 0.05). The lack of a statistically significant alteration in HSP27 and ERK1/2 phosphorylations suggests that single or combined RF radiation exposure did not elicit activation of HSP27 and ERK1/2 in MCF10A cells.     

抗菌肽merecidin通过ERK/mTOR 信号通路对肺癌A549细胞增殖、凋亡、迁移和侵袭的影响

目的 探讨抗菌肽merecidin通过ERK/mTOR 信号通路对肺癌A549细胞增殖、凋亡、迁移和侵袭的影响。方法 实验分为对照组Control、抗菌肽Merecidin干预组和雷帕霉素Rapamycin干预组。通过CCK-8 法检测A549细胞的增殖能力,通过流式细胞术检测A549细胞凋亡和周期,通过平板划痕试验和Transwell检测A549细胞的迁移和侵袭能力,通过 Western blot 法检测A549细胞中MAPK1、MEK2、mTOR、PRAS40、EIF4EBP1 磷酸化蛋白的表达量。结果 抗菌肽merecidin能够明显抑制A549的增殖能力,处理24 h后的 IC50值为10.01 μmol /L(P<0.05)。与control组比较,抗菌肽merecidin处理后促进细胞凋亡(P<0.05),阻滞细胞周期于S期(P<0.05),细胞的迁移及侵袭能力均降低(P<0.05)。同时抗菌肽merecidin可抑制p-MAPK1和p-MEK2蛋白的表达,并且降低了mTOR、PRAS40和EIF4EBP1 的磷酸化水平(P<0.05)。结论 抗菌肽merecidin可抑制肺癌A549细胞增殖、迁移和侵袭能力,促进细胞凋亡,阻滞细胞周期于S期,该作用可能与其抑制ERK/mTOR通路有关。     

ERK1/2通路在AcSDKP抑制PDGF诱导的大鼠肺成纤维细胞增殖和胶原合成中的作用

目的 探讨细胞外信号调节激酶(ERK)1/2通路在N-乙酰基-丝氨酰-天门冬酰-赖氨酰-脯氨酸(AcSDKP)抑制血小板源性生长因子(PDGF)诱导的大鼠肺成纤维细胞增殖和胶原合成中的作用.方法 取新生Wistar大鼠20只,获得原代及传代培养的肺成纤维细胞.实验分为:(1)对照组(含体积分数为0.4%的胎牛血清的DMEM组);(2)PDGF组;(3)PD98059+PDGF组(25 μmol/L PD98059+10 ng/ml PDGF);(4)AcSDKP+PDGF组(1x10-8mol/L AcSDKP+10 ng/ml PDGF).采用噻唑蓝(MTT)法检测肺成纤维细胞的代谢活力,免疫细胞化学法、Western blot法检测Ⅰ、Ⅲ型胶原蛋白表达的改变;采用Western blot法检测ERK1/2及磷酸化-ERK1/2蛋白表达的改变.结果 与对照组相比,PDGF组大鼠肺成纤维细胞代谢活力增强,Ⅰ、Ⅲ型胶原蛋白表达增强,磷酸化-ERK1/2蛋白表达增高,差异均有统计学意义(P<0.05).AcSDKP+PDGF组细胞代谢活力明显低于PDGF组,免疫细胞化学法检测结果 显示,AcSDKP+PDGF组Ⅰ、Ⅲ型胶原蛋白表达分别为PDGF组的69.3%和67.2%.Western blot法检测结果 显示,AcSDKP+PDGF组细胞内Ⅰ、Ⅲ型胶原蛋白表达分别为PDGF组的92.4%和78.0%,磷酸化-ERK1/2蛋白表达为PDGF组的83.5%,差异均有统计学意义(P<0.05).结论 ERK1/2通路在AcSDKP抑制PDGF诱导的大鼠肺成纤维细胞增殖和胶原合成中发挥了重要作用.     

石英通过丝裂素活化蛋白激酶通路引起人胚肺成纤维细胞周期的改变

目的 探讨在石英刺激的人胚肺成纤维细胞(human embryo lung fibroblasts,HELF)中细胞外信号调节蛋白激酶(ERK)、应激活化蛋白激酶(JNK),细胞周期蛋白DI(cyclin D1)通路在石英诱导的细胞周期改变中的作用.方法 建立稳定转染转录因子AP-1荧光素酶报告基冈质粒的HELF系(HELF-AP-1)及AP-1荧光素酶报告基因质粒与丝裂素活化蛋白激酶(MAPK)显性失活突变体质粒(DN-ERK、DN-JNK和DN-p38)分别共转染的HELF系(简称DN-ERK、DN-JNK和DN-p38).将HELF-AP-1、DN-ERK、DN-JNK和DN-p38细胞分为对照组和石英组(共8组),各对照组不加任何处理,石英组用200 μg/ml石英处理HELF细胞24 h.用免疫印迹(Western blot)法和免疫荧光法检测cyclin D1、细胞周期蛋白依赖激酶4(CDK4)和E2F-4蛋白表达;采用显性失活突变体技术验证MAPKs信号转导通路的上下游关系及其与细胞周期的关系;用流式细胞术检测细胞周期变化.结果 HELF-AP-1+石英组G1期细胞所占比例下降,S期细胞所占比例升高,与HELF-AP-1对照组的差异有统计学意义(P＜0.05).抑制ERK或JNK表达后,与HELF-AP-1对照组比较,DN-ERK+石英组和DN-JNK+石英组G1期细胞百分比无明显变化.抑制p38后,DN-p38+石英组G1期细胞百分率明显下降,与HELF-AP-1对照组的差异有统计学意义(P＜0.05).与HELF-AP-1石英组比较,DN-ERK+石英组和DN-JNK+石英组CDK4表达降低和E2F-4表达增多,而DN-p38+石英组CDK4表达和E2F-4表达没有改变.与HELF-AP-1+石英组比较,DN-ERK+石英组和DN-JNK+石英组cyclin D1表达降低,而DN-p38+石英组cyclin D1没有改变.结论 ERK和JNK通过cyclin D1和CDK4介导石英诱导的HELF的细胞周期改变,而石英诱导的细胞周期改变与p38无关.

Abstract：

Objective To investigate the roles of mitogen-activated protein kinases (MAPK) on silica-induced cell cycle changes. Methods After cells were treated with 200 μg/ml silica, Western blot and Immunofluorescence assays were utilized to detect the expression of cyclin D1, CDK4 and E2F-4, Flow cytometry was used to detect cell cycle progression, the dominant negative mutants techniques were used to investigate silica-induced signal pathway and the effects of which in silica-induced cell cycle changes. Results After cells were exposed to 200 μg/ml silica 24 h, the results of present study showed the proportion of cells in G1 phases was decreased. Silica-induced cell cycle alternation was markedly impaired by stable expression of a dominant negative mutants of ERK or JNK, but not p38. It was found that ERK and JNK were involved in silica-induced cyclin D1 and CDK4 overexpression and the decreased expression of E2F-4. Conclusion ERK and JNK, but not p38, mediated silica-induced cell cycle changes in human embryo lung fibroblasts.     

电离辐射对小鼠脾脏B淋巴细胞损伤的研究

目的 探讨电离辐射对小鼠脾细胞活性的影响,阻断p38-MAPK通路对小鼠脾细胞的防护作用。方法 从体内、体外实验研究不同剂量电离辐射对小鼠脾细胞活性的影响,分别在照射前、后给与p38 MAPK通路阻断剂SB203580,观察对辐射损伤的防护和治疗作用。结果 在体外实验中,辐射对小鼠脾细胞活性的破坏作用与剂量正相关;体内实验表明低剂量的辐射可以提高脾细胞的活性,高剂量辐射能破坏其活性;在亚致死剂量的辐射下,照射后用SB203580对小鼠脾细胞活性的治疗作用不明显,照射前用SB203580对小鼠脾细胞活性具有较好的保护作用。结论 阻断p38-MAPK通路可以有效预防辐射对小鼠脾细胞的损伤,无明显的治疗作用。     

石英致MAPK/cyclinD1-CDK4信号转导通路的活化

目的探讨石英诱导的人胚肺成纤维细胞(HELF)中丝裂素活化蛋白激酶(MAPK)/细胞周期蛋白和细胞周期蛋白依赖激酶(cyclin D1-CDK4)信号转导通路的活化。方法两种处理方式:(1)石英刺激细胞2h后,收获细胞;(2)石英长时间(2个月)作用于细胞,使细胞具有部分转化细胞的特征(S-HELF),检测信号蛋白因子和细胞周期的变化。分别采用Western blot、免疫细胞化学和流式细胞术方法检测细胞内信号蛋白和细胞周期的改变。选用特异化学抑制剂或分子抑制剂抑制上游激酶,检测下游激酶的变化。结果HELF暴露于石英粉尘2 h后,可以导致MAPK家族中ERK1/2、p38和JNK1/2 3个亚家族的磷酸化水平升高。在S-HELF中,只有细胞外调节蛋白激酶(ERK)和C-Jun氨基末端激酶[JNK1(p46)]较未处理的HELF磷酸化水平增高,而JNK2(p54)的磷酸化水平没有变化,p38的磷酸化水平反而下降。cyclin D1和CDK4蛋白在S-HELF中较HELF中表达增多。抑制ERK和JNK活化或者抑制核转录因子活化蛋白1(AP- 1)的活化后,S-HELF中cyclin D1和CDK4蛋白过表达得到控制。而抑制p38的活性不能改变cyclin D1和CDK4蛋白过表达。结论石英刺激HELF2h后可诱导ERK、JNK和p38的活化,而S-HELF中ERK、JNK活化,p38没有被活化。S-HELF中,cyclin D1和CDK4蛋白质过表达与ERK、JNK和AP-1活化有关。     

白藜芦醇抑制IGF-I促人肺腺癌A549细胞增殖作用及其机制的研究

目的观察白藜芦醇对IGF-I介导人肺腺癌细胞增殖的影响及其IGF-I受体、AKT、p-AKT、ERK1/2、p-ERK1/2的表达变化。方法应用MTT方法测定细胞增殖,采用RT-PCR检测IGF-I受体mRNA表达,并应用免疫印迹方法检测AKT、p-AKT及ERK1/2、p-ERK1/2蛋白表达水平。结果不同浓度IGF-I(2.5～15nM)可显著促进A549细胞增殖(F=22.321,P=0.011),白藜芦醇(6.25～50μM)与10nMIGF-I共作用于A549细胞,均可抑制IGF-I的促A549细胞增殖作用(F=11.211,P=0.032),其中尤以25μM、50μM白藜芦醇的抑制增殖作用显著(P=0.034;P=0.012),并且,白藜芦醇可有效降低IGF-I受体mRNA表达以及降低IGF-I增强的AKT及ERK1/2磷酸化。结论白藜芦醇能够抑制IGF-I介导的A549肺癌细胞增殖,其作用机制可能与白藜芦醇降低A549肺癌细胞IGF-I受体mRNA表达及AKT、ERK1/2磷酸化相关。     

ERK和JNK/AP-1通路参与石英诱导的细胞周期改变

目的 探讨在石英刺激的人胚肺成纤维细胞(human embryo lung fibroblasts,HELF)中转录因子活化蛋白-1(activator protein-1,AP-1)的活性改变,以及丝裂原活化蛋白激酶(mitogen activated protein kinase,MAPK),AP-1通路在石英诱导的细胞周期改变中的作用.方法 用200 μg/ml石英处理HELF细胞;用免疫荧光法检测细胞外调节蛋白激酶(extracellular signal-regdated protein kinase,ERK)和c-Jun氨基末端激酶(c-Jun N-terminal kinase,JNK)蛋白磷酸化水平及细胞分布;运用AP-1荧光素酶报告基因技术检测AP-1荧光素酶活力;用MAPK显性失活突变体(dominant negative mutant,DN)(DN-ERK2、DN-JNKl和DN-p38)证明通路的上下游关系;用流式细胞术检测细胞周期变化.结果 用200μg/ml石英分别处理转染AP-1报告基因的细胞(HELF-AP-1)6、12、24h,结果显示,AP-1活性随着时间变化而发生变化,6 h活性增强,12 h活性达峰值,24 h活性略有降低;用200 μg/ml石英分别处理细胞1和2 h,结果显示,ERK和JNK在石英刺激1 h后,磷酸化水平升高,主要集中于胞浆,2 h后磷酸化水平进一步升高,并主要集中于胞核;200 μg/ml石英处理细胞24 h,G1期细胞所占比例从(63.80±9.57)%下降到(32.23±7.22)%,S期细胞所占比例从(35.17±10.33)%升高到(66.00±8.07)%;AP-1化学抑制剂姜黄素(20μmol/L)可明显减弱石英引起的G1期细胞比例减少和S期细胞比例增加;DN-ERK和DN-JNK的过表达均可明显降低石英诱导的AP-1活性增强,DN-p38的过表达对石英诱导的AP-1活性增强无明显影响.结论 200 μg/ml石英可诱导AP-1活性增强,并通过ERK、JNK/AP-1通路诱导细胞周期改变.     

不同剂量电离辐射对大肠癌HCT-8细胞P-gp表达的影响

目的 通过检测不同剂量电离辐射对大肠癌细胞多药耐药基因MDR1的蛋白表达产物P-糖蛋白(P-gp)的影响,探讨逆转肿瘤多药耐药的方法。方法 采用流式细胞术检测P-gp蛋白表达的变化。结果 与假照组相比,2Gy大剂量照射后P-gp阳性细胞百分率明显增加(P<0.01),先给予低剂量照射(0.05Gy,0.1Gy)后,再给予大剂量照射,P-gp阳性细胞百分率亦有明显增加(P<0.05),0.2Gy+2Gy组P-gp阳性细胞百分率明显增加(P<0.01)。与单纯2Gy大剂量照射组比较,0.1Gy+2Gy组P-gp阳性细胞百分率明显降低(P<0.05)。结论 低剂量辐射可以逆转大剂量辐射所致的多药耐药性。     

Cell cycle checkpoint and apoptosis induction in glioblastoma cells and fibroblasts irradiated with carbon beam

This study was conducted in order to evaluate the cytotoxicity of high linear-energy-transfer (LET) ionizing radiation (IR) on glioblastoma cells and fibroblasts using different modes of cell inactivation assays. Two human glioblastoma cell lines with or without p53-mutation, and fibroblasts were used as materials. Gamma rays and 290 MeV/u carbon beams with LET values of 20, 40, 80 keV/mum were used. To evaluate cell inactivation, we used colony formation assay, morphological detection of apoptosis, and flow-cytometry. Serial expressions of p53 and p21 were analyzed by immunoblotting. High-LET IR reduced the reproductive potency of these cells to identical levels in spite of differences in gamma-sensitivity, and yield of cell death correlated to LET values. A p53-wild-type glioblastoma cell line demonstrated a higher yield of apoptosis than other cell lines, whereas fibroblasts hardly displayed any cell death indicating senescence-like growth arrest even after high LET IR. A p53-mutant tumor cell line demonstrated very low yield of cell death with prominent G2/M arrest. Results of radiosensitivity differ according to what mode of cell inactivation is selected. While fibroblasts depend on G1 block after IR, G2/M blocks may play crucial roles in the radioresistance of p53-mutant glioblastoma cells.