下调X连锁凋亡抑制蛋白基因表达增强结肠癌细胞对5-氟尿嘧啶敏感性的研究

目的 观察下调X连锁凋亡抑制蛋白(X-linked inhibitor of apoptosis protein,XIAP)基因表达后结肠癌细胞对5-氟尿嘧啶(5-Fu)敏感性的变化.方法 采用脂质体包裹方法将携带靶向干扰XIAP序列的表达载体转染人结肠癌细胞HCT-8和HCT116,观察结肠癌细胞生长活性的变化;应用5-Fu后,观察结肠癌细胞对5-Fu敏感性的变化,并应用蛋白印迹方法检测结肠癌细胞内凋亡相关因子caspase-3的活性变化. 结果抑制XIAP基因表达后,结肠癌细胞HCT-8和HCT116的生长活性受到有效抑制;结肠癌细胞HCT-8对5-Fu的耐药性得到逆转(P＜0.01),HCT116对5-Fu的敏感性得到明显提高(P＜0.05);结肠癌细胞内caspase-3的表达活性提高,5-Fu诱导细胞凋亡的活性得到增强. 结论XIAP的表达是结肠癌细胞HCT-8和HCT116对5-Fu耐药的一个重要机制;抑制XIAP基因表达后能够增强结肠癌细胞HCT-8和HCT116对5-Fu化疗的敏感性.

Abstract：

Objective To investigate sensitivity of colon cancer cells to 5-fluorouracil after downregulation of XIAP gene expression. Method Colon cancer cells HCT-8 and HCT116 were transfected with a short hairpin RNA targeted to XIAP by liposome, cells viability were examined.5-fluorouracil was applied into two kinds of colon cancer cells. Tumor cells sensitiviy to chemotherapeutic drug was evaluated. Caspase-3 activity in tumor cells was examined by Western blot. Result After downregulation of XIAP expression, cell growing viability of these two kinds of colon cancer cells was restricted, HCT-8 resistance to 5-fluorouracil was reversed ( P ＜ 0. 01 ), HCT116 sensitivity to 5-fluorouracil was enhanced (P ＜ 0.05), caspase-3 expression in colon cancer cells was highly activated, apoptosis inducing activity of 5-fluorouracil was increased significantly. Conclusions XIAP expression was a important mechanism in colon cancer cells HCT-8 and HCT 116 resistant to 5-fluorouracil, sensitivity to 5-fluorouracil of HCT-8 and HCT-116 was increased by downregulation of XIAP expression.     

Chimeric molecules facilitate the degradation of androgen receptors and repress the growth of LNCaP cells

Post-translational degradation of protein plays an important role in cell life. We employed chimeric molecules （dihydrotestosterone-based proteolysis-targeting chimeric molecule [DHT-PROTAC]） to facilitate androgen receptor （AR） degradation via the ubiquitin-proteasome pathway （UPP） and to investigate the role of AR in cell proliferation and viability in androgen-sensitive prostate cancer cells. Western blot analysis and immunohistochemistry were applied to analyse AR levels in LNCaP cells after DHT-PROTAC treatment. Cell counting and the 3-（4,5-dimethylthiazol-2-yl）-2,5- diphenyl tetrazolium bromide （MTT） cell viability assay were used to evaluate cell proliferation and viability after AR elimination in both LNCaP and PC-3 cells. AR was tagged for elimination via the UPP by DHT-PROTAC, and this could be blocked by proteasome inhibitors. Degradation of AR depended on DHT-PROTAC concentration, and either DHT or an ALAPYIP-（arg）8 peptide could compete with DHT-PROTAC. Inhibition of cell proliferation and decreased viability were observed in LNCaP cells, but not in PC-3 or 786-0 cells after DHT-PROTAC treatment. These data indicate that AR elimination is facilitated via the UPP by DHT-PROTAC, and that the growth of LNCaP cells is repressed after AR degradation.     

ShRNA-mediated gene silencing of β-catenin inhibits growth of human colon cancer cell Colo205 in vitro

Objective To observe the gene silencing and disruption of WNT pathway mediated by the specific shRNA targeted against β-catenin and its effect on cell proliferation of the human colon cancer cell line Colo205. Methods The shRNA plasmid vectors against β-catenin were constructed and transfected into Colo205 ceils with LipofectamineTM 2000. The expression of β-catenin was detected by RT-PCR and Western blot. Immunofluorescence staining was also performed to detect the β-catenin protein expression in cells. The cell proliferation inhibition was determined by MTT assay and soft agar colony formation assay. Results The shRNA vectors targeted against β-catenin were successfully constructed and efficiently suppressed the expression of β-catenin mRNA and protein (P<0.05). The expression inhibition rates were 47.89% and 45.26% at the mRNA and protein level respectively. Immunofluorescence microscopy also demonstrated the inhibition of β-catenin protein induced by these specific shRNAs. The MTT assay indicated that the specific shRNA resulted in significant inhibition of cell growth on the culture plates in time-dependent manner. At 72 h post-transfection, the cell viability of CAT group was 48.5%, which was significantly different as compared with that of blank control group's 91.3%(P<0.05). In the soft agar, there were 9, 46, 43 cell colonies in the CAT, blank, and negative control groups respectively, which were significantly different (P<0.05). Conclusions The specific shRNAs targeted against β-catenin has a gene silencing effect and blocks the WNT signaling pathway, which can inhibit the growth of Colo205 cells.     

ShRNA-mediated gene silencing of β-catenin inhibits growth of human colon cancer cell Colo205 in vitro

Objective To observe the gene silencing and disruption of WNT pathway mediated by the specific shRNA targeted against β-catenin and its effect on cell proliferation of the human colon cancer cell line Colo205. Methods The shRNA plasmid vectors against β-catenin were constructed and transfected into Colo205 ceils with LipofectamineTM 2000. The expression of β-catenin was detected by RT-PCR and Western blot. Immunofluorescence staining was also performed to detect the β-catenin protein expression in cells. The cell proliferation inhibition was determined by MTT assay and soft agar colony formation assay. Results The shRNA vectors targeted against β-catenin were successfully constructed and efficiently suppressed the expression of β-catenin mRNA and protein (P<0.05). The expression inhibition rates were 47.89% and 45.26% at the mRNA and protein level respectively. Immunofluorescence microscopy also demonstrated the inhibition of β-catenin protein induced by these specific shRNAs. The MTT assay indicated that the specific shRNA resulted in significant inhibition of cell growth on the culture plates in time-dependent manner. At 72 h post-transfection, the cell viability of CAT group was 48.5%, which was significantly different as compared with that of blank control group's 91.3%(P<0.05). In the soft agar, there were 9, 46, 43 cell colonies in the CAT, blank, and negative control groups respectively, which were significantly different (P<0.05). Conclusions The specific shRNAs targeted against β-catenin has a gene silencing effect and blocks the WNT signaling pathway, which can inhibit the growth of Colo205 cells.     

ShRNA-mediated gene silencing of β-catenin inhibits growth of human colon cancer cell Colo205 in vitro

Objective To observe the gene silencing and disruption of WNT pathway mediated by the specific shRNA targeted against β-catenin and its effect on cell proliferation of the human colon cancer cell line Colo205. Methods The shRNA plasmid vectors against β-catenin were constructed and transfected into Colo205 ceils with LipofectamineTM 2000. The expression of β-catenin was detected by RT-PCR and Western blot. Immunofluorescence staining was also performed to detect the β-catenin protein expression in cells. The cell proliferation inhibition was determined by MTT assay and soft agar colony formation assay. Results The shRNA vectors targeted against β-catenin were successfully constructed and efficiently suppressed the expression of β-catenin mRNA and protein (P<0.05). The expression inhibition rates were 47.89% and 45.26% at the mRNA and protein level respectively. Immunofluorescence microscopy also demonstrated the inhibition of β-catenin protein induced by these specific shRNAs. The MTT assay indicated that the specific shRNA resulted in significant inhibition of cell growth on the culture plates in time-dependent manner. At 72 h post-transfection, the cell viability of CAT group was 48.5%, which was significantly different as compared with that of blank control group's 91.3%(P<0.05). In the soft agar, there were 9, 46, 43 cell colonies in the CAT, blank, and negative control groups respectively, which were significantly different (P<0.05). Conclusions The specific shRNAs targeted against β-catenin has a gene silencing effect and blocks the WNT signaling pathway, which can inhibit the growth of Colo205 cells.     

ShRNA-mediated gene silencing of β-catenin inhibits growth of human colon cancer cell Colo205 in vitro

Objective To observe the gene silencing and disruption of WNT pathway mediated by the specific shRNA targeted against β-catenin and its effect on cell proliferation of the human colon cancer cell line Colo205. Methods The shRNA plasmid vectors against β-catenin were constructed and transfected into Colo205 ceils with LipofectamineTM 2000. The expression of β-catenin was detected by RT-PCR and Western blot. Immunofluorescence staining was also performed to detect the β-catenin protein expression in cells. The cell proliferation inhibition was determined by MTT assay and soft agar colony formation assay. Results The shRNA vectors targeted against β-catenin were successfully constructed and efficiently suppressed the expression of β-catenin mRNA and protein (P<0.05). The expression inhibition rates were 47.89% and 45.26% at the mRNA and protein level respectively. Immunofluorescence microscopy also demonstrated the inhibition of β-catenin protein induced by these specific shRNAs. The MTT assay indicated that the specific shRNA resulted in significant inhibition of cell growth on the culture plates in time-dependent manner. At 72 h post-transfection, the cell viability of CAT group was 48.5%, which was significantly different as compared with that of blank control group's 91.3%(P<0.05). In the soft agar, there were 9, 46, 43 cell colonies in the CAT, blank, and negative control groups respectively, which were significantly different (P<0.05). Conclusions The specific shRNAs targeted against β-catenin has a gene silencing effect and blocks the WNT signaling pathway, which can inhibit the growth of Colo205 cells.     

ShRNA-mediated gene silencing of β-catenin inhibits growth of human colon cancer cell Colo205 in vitro

Objective To observe the gene silencing and disruption of WNT pathway mediated by the specific shRNA targeted against β-catenin and its effect on cell proliferation of the human colon cancer cell line Colo205. Methods The shRNA plasmid vectors against β-catenin were constructed and transfected into Colo205 ceils with LipofectamineTM 2000. The expression of β-catenin was detected by RT-PCR and Western blot. Immunofluorescence staining was also performed to detect the β-catenin protein expression in cells. The cell proliferation inhibition was determined by MTT assay and soft agar colony formation assay. Results The shRNA vectors targeted against β-catenin were successfully constructed and efficiently suppressed the expression of β-catenin mRNA and protein (P<0.05). The expression inhibition rates were 47.89% and 45.26% at the mRNA and protein level respectively. Immunofluorescence microscopy also demonstrated the inhibition of β-catenin protein induced by these specific shRNAs. The MTT assay indicated that the specific shRNA resulted in significant inhibition of cell growth on the culture plates in time-dependent manner. At 72 h post-transfection, the cell viability of CAT group was 48.5%, which was significantly different as compared with that of blank control group's 91.3%(P<0.05). In the soft agar, there were 9, 46, 43 cell colonies in the CAT, blank, and negative control groups respectively, which were significantly different (P<0.05). Conclusions The specific shRNAs targeted against β-catenin has a gene silencing effect and blocks the WNT signaling pathway, which can inhibit the growth of Colo205 cells.     

ShRNA-mediated gene silencing of β-catenin inhibits growth of human colon cancer cell Colo205 in vitro

Objective To observe the gene silencing and disruption of WNT pathway mediated by the specific shRNA targeted against β-catenin and its effect on cell proliferation of the human colon cancer cell line Colo205. Methods The shRNA plasmid vectors against β-catenin were constructed and transfected into Colo205 ceils with LipofectamineTM 2000. The expression of β-catenin was detected by RT-PCR and Western blot. Immunofluorescence staining was also performed to detect the β-catenin protein expression in cells. The cell proliferation inhibition was determined by MTT assay and soft agar colony formation assay. Results The shRNA vectors targeted against β-catenin were successfully constructed and efficiently suppressed the expression of β-catenin mRNA and protein (P<0.05). The expression inhibition rates were 47.89% and 45.26% at the mRNA and protein level respectively. Immunofluorescence microscopy also demonstrated the inhibition of β-catenin protein induced by these specific shRNAs. The MTT assay indicated that the specific shRNA resulted in significant inhibition of cell growth on the culture plates in time-dependent manner. At 72 h post-transfection, the cell viability of CAT group was 48.5%, which was significantly different as compared with that of blank control group's 91.3%(P<0.05). In the soft agar, there were 9, 46, 43 cell colonies in the CAT, blank, and negative control groups respectively, which were significantly different (P<0.05). Conclusions The specific shRNAs targeted against β-catenin has a gene silencing effect and blocks the WNT signaling pathway, which can inhibit the growth of Colo205 cells.     

ShRNA-mediated gene silencing of β-catenin inhibits growth of human colon cancer cell Colo205 in vitro

Objective To observe the gene silencing and disruption of WNT pathway mediated by the specific shRNA targeted against β-catenin and its effect on cell proliferation of the human colon cancer cell line Colo205. Methods The shRNA plasmid vectors against β-catenin were constructed and transfected into Colo205 ceils with LipofectamineTM 2000. The expression of β-catenin was detected by RT-PCR and Western blot. Immunofluorescence staining was also performed to detect the β-catenin protein expression in cells. The cell proliferation inhibition was determined by MTT assay and soft agar colony formation assay. Results The shRNA vectors targeted against β-catenin were successfully constructed and efficiently suppressed the expression of β-catenin mRNA and protein (P<0.05). The expression inhibition rates were 47.89% and 45.26% at the mRNA and protein level respectively. Immunofluorescence microscopy also demonstrated the inhibition of β-catenin protein induced by these specific shRNAs. The MTT assay indicated that the specific shRNA resulted in significant inhibition of cell growth on the culture plates in time-dependent manner. At 72 h post-transfection, the cell viability of CAT group was 48.5%, which was significantly different as compared with that of blank control group's 91.3%(P<0.05). In the soft agar, there were 9, 46, 43 cell colonies in the CAT, blank, and negative control groups respectively, which were significantly different (P<0.05). Conclusions The specific shRNAs targeted against β-catenin has a gene silencing effect and blocks the WNT signaling pathway, which can inhibit the growth of Colo205 cells.     

ShRNA-mediated gene silencing of β-catenin inhibits growth of human colon cancer cell Colo205 in vitro

Objective To observe the gene silencing and disruption of WNT pathway mediated by the specific shRNA targeted against β-catenin and its effect on cell proliferation of the human colon cancer cell line Colo205. Methods The shRNA plasmid vectors against β-catenin were constructed and transfected into Colo205 ceils with LipofectamineTM 2000. The expression of β-catenin was detected by RT-PCR and Western blot. Immunofluorescence staining was also performed to detect the β-catenin protein expression in cells. The cell proliferation inhibition was determined by MTT assay and soft agar colony formation assay. Results The shRNA vectors targeted against β-catenin were successfully constructed and efficiently suppressed the expression of β-catenin mRNA and protein (P<0.05). The expression inhibition rates were 47.89% and 45.26% at the mRNA and protein level respectively. Immunofluorescence microscopy also demonstrated the inhibition of β-catenin protein induced by these specific shRNAs. The MTT assay indicated that the specific shRNA resulted in significant inhibition of cell growth on the culture plates in time-dependent manner. At 72 h post-transfection, the cell viability of CAT group was 48.5%, which was significantly different as compared with that of blank control group's 91.3%(P<0.05). In the soft agar, there were 9, 46, 43 cell colonies in the CAT, blank, and negative control groups respectively, which were significantly different (P<0.05). Conclusions The specific shRNAs targeted against β-catenin has a gene silencing effect and blocks the WNT signaling pathway, which can inhibit the growth of Colo205 cells.     

Induction of mitotic arrest and apoptosis in human prostate cancer pc-3 cells by evodiamine

PURPOSE: Although evodiamine, an alkaloid isolated from Evodiae fructus, has been reported to exert anticancer activities, to our knowledge its target and mechanism of action have not yet been explored. We examined the anticancer activities and action mechanism of evodiamine. MATERIALS AND METHODS: Human prostate cancer PC-3 cells were used in this study. The cytotoxic effect and cell growth inhibition were examined using the MTT (3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide) assay and sulforhodamine B assay, respectively. The apoptotic effect was determined using TUNEL assay and the progression of cells through the cell cycle and cell apoptosis were examined by FACScan flow cytometry (Becton Dickinson, Sunnyvale, California). In situ mitotic spindle detection and in vitro tubulin polymerization assay were performed by immunofluorescence staining for beta-tubulin and CytoDYNAMIX ScreenTM3 (CDS-03) kits (Cytoskeleton, Denver, Colorado). RESULTS: It was found that treatment of PC-3 cells with evodiamine decreased the cell number in a concentration and time dependent manner, and effectively inhibited PC-3 cell growth via the induction of cell cycle arrest at the G2/M phase and subsequent apoptosis. In an in situ assay we found that evodiamine inhibited microtubule spindle formation. In a cell-free assay system of tubulin polymerization evodiamine inhibited the polymerization of microtubules in a concentration dependent manner. CONCLUSIONS: These data suggest that evodiamine shows anticancer activity through inhibition of tubulin polymerization. This antitubulin activity might make evodiamine a potential anticancer drug.     

Inhibition of Autophagy by 3-MA Enhances the Effect of 5-FU-Induced Apoptosis in Colon Cancer Cells

Background  5-fluorouracil-(5-FU)-based adjuvant chemotherapy is widely used for the treatment of colorectal cancer. However, 5-FU resistance in the course of treatment has become more common. Therefore, new therapeutic strategies and/or new adjuvant drugs still need to be explored. Methods  Two colon-cancer-derived cell lines, colon26 and HT29, were used to investigate the effect of 5-FU, 3-methyladenine (3-MA, an autophagy inhibitor), or their combination on apoptotic cell death and autophagy. MTT assay, Hochest plus propidium iodide (PI) staining, and DNA fragmentation assay were used to observe apoptosis. Meanwhile, monodansylcadaverine (MDC) was used to detect autophagy. Finally, immunoblotting assay was used to explore the molecular change that occurred. Results  We observed the apoptosis induced by 5-FU in colon cancer cells. Meanwhile, autophagy was also stimulated. The combination treatment of 3-MA and 5-FU significantly increased the apoptotic cell death. By isolating the subcellular fractions of mitochondria and cytosol, we observed that the release of cytochrome c was increased in combination-treated cells. Cytochrome c resulted in the activation of caspase-3, thus activating PARP. Moreover, the anti-apoptotic protein, Bcl-xL, was significantly downregulated by 3-MA. Conclusions  Our results suggest that 5-FU-induced apoptosis in colon cancer cells can be enhanced by the inhibitor of autophagy, 3-MA. Autophagy might play a role as a self-defense mechanism in 5-FU-treated colon cancer cells, and its inhibition could be a promising strategy for the adjuvant chemotherapy of colon cancer.     

吴茱萸碱对大肠癌细胞侵袭和中期因子基因表达的影响

目的 观察吴茱萸碱对大肠癌细胞侵袭的影响和可能机理.方法 采用不同浓度的吴茱萸碱处理人大肠癌SW620细胞后,以软琼脂集落培养试验检测癌细胞锚着不依赖性增生,以Boyden小室模型方法检测癌细胞侵袭能力;分别以荧光实时定量RT-PCR和Western blot方法检测癌细胞中期因子(midkine,MK)基因mRNA和蛋白水平.结果 大肠癌Sw620细胞经吴茱萸碱处理后,恶性增生和穿膜细胞数均明显下降,且呈剂量依赖性(P<0.05,P<0.05).吴茱萸碱处理组MK基因mRNA和蛋白水平均明显下调,且呈时间和浓度依赖性(P<0.05,P<0.05). 结论 吴茱萸碱可明显抑制大肠癌细胞侵袭,其机制可能与下调MK基因表达有关.     

甘草素对人乳腺癌MCF-7细胞增殖、凋亡及自噬的影响

目的：观察甘草素对人乳腺癌MCF-7细胞生长、凋亡及自噬的作用。方法：不同浓度（0.05,0.10,0.20,0.40 mmol/L）的甘草素处理MCF-7细胞24,48,72 h后,采用MTT比色法测定细胞存活率。以上浓度的甘草素处理MCF-7细胞48 h后,用Hoechst荧光染色法观察细胞凋亡情况,用吖啶橙（AO）染色,观察细胞自噬。结果： 随着甘草素浓度的增加及作用时间的延长,MCF-7细胞的存活率不断降低,部分结果与对照组比较,差异有统计学意义（P<0.05或P<0.01）;随着草素浓度的增加,MCF-7细胞的凋亡率不断增高,从0.20 mmol/L开始,与对照组比较,差异有统计学意义（均P<0.01）。各浓度的甘草素作用下,MCF-7细胞均产生自噬现象,但随着甘草素浓度的增加,自噬活性呈现先升后降的趋势。结论：甘草素可抑制人乳腺癌MCF-7细胞的生长,该作用与其促进凋亡及诱导自噬有关。

     

反义寡聚核苷酸抑制人膀胱癌T24细胞系端粒酶活性的研究

目的研究反义寡聚核苷酸(asONs)能否抑制人膀胱肿瘤T24细胞系端粒酶活性和增殖活性。方法设计并合成2条针对端粒酶RNA模板区的asONs片段,在其作用于T24细胞第5天时,用7复孔法用聚合酶链反应-酶标法(PCR-ELISA)检测其对端粒酶活性的影响;分别在实验的第1、3、5、7天,用7复孔四唑盐比色试验(MTT)法检测其对细胞增殖活性的影响。结果经不同浓度(0、5、10μmol/L)处理5d后T24细胞端粒酶活性受到抑制,吸光度(A)值分别为0.79±0.10、0.24±0.14;经10μmol/L处理1、3、5、7d,T24细胞的增殖活性逐渐下降,A值分别为0.59±0.11、0.39±0.09、0.21±0.02、0.19±0.07,各组分别比较差异有非常显著性(P＜0.001)。结论asONs能够同时抑制人膀胱肿瘤T24细胞系端粒酶及细胞增殖活性,提示asONs可能通过抑制端粒酶活性达到抑制人膀胱肿瘤T24细胞系的增殖。     

索拉菲尼对肝癌细胞HepG2自噬的抑制作用

目的：研究化疗药物索拉菲尼（Sorafenib）对肝癌细胞HepG2自噬的作用及自噬与细胞增殖、细胞凋r_的关系。方法：常规细胞培养,以10μmol／L的索拉菲尼作用不同时间,采用MDC染色,在荧光显微镜下观察自噬泡的情况：用Western印迹检测自噬相关蛋白LC3的动态变化;用3-MA抑制肝癌细胞中自噬的表达,并用CCK8法检测索拉菲尼及其联合3-MA对细胞生存率的影响,用AnnexinV／PI流式细胞仪检测抑制自噬后凋亡的变化。结果：HepG2经索拉菲尼作用后,自噬泡明显减少,LC3蛋白尤其是LC3-Ⅱ随着作用时间延长逐渐减弱;索拉菲尼联合3-MA可进一步抑制HepG2细胞中自噬的表达,抑制自噬后细胞死亡明显增加,特别是细胞凋亡明显增加。结论：索拉菲尼抗肝癌作用可能与抑制肝癌细胞自噬有关。     

Effect of cyclosporine A on autophagy-lysosomal pathway in tubular epithelial cells

Objective To investigate the effect of cyclosporine A (CsA) on autophagy-lysosomal pathway in tubular epithelial cells. Methods Human renal tubular epithelial cell line (HK-2 cell) was treated with different concentrations (3, 5 and 10 μmol/L) of CsA for 24 h. Then the viability and apoptosis of cells were measured by MTT assay or AnnexinV-PI staining followed by flow cytometry analysis, respectively. Autophagy-related protein LC3-Ⅱ and p62 were detected by immunofluorescence assay. Autophagic flux was analyzed in HK-2 cells transfected with a tandem mRFP-GFP fluorescent-tagged LC3 (tfLC3) plasmid by laser confocal microscope. The lysosomal degradation was evaluated by DQ-ovalbumin staining followed by flow cytometry analysis. Results The viability of HK-2 cells was significantly decreased with CsA stimulation when compared with control group (P＜0.01), but the number of apoptotic cells was markedly increased by CsA treatment (P＜0.05). Compared with the control group, different doses of CsA dramatically increased the expressions of LC3-Ⅱ(P＜0.01) and p62 (P＜0.05) in HK-2 cells. Moreover, HK-2 cells treated with CsA displayed a significant increase in autophagosomes but a marked decrease in autolysosomes. In HK-2 cells, exposured to CsA caused a decrease in lysosomal degradation by DQ-ovalbumin staining when compared with control group (P＜0.01). Conclusion Blockade of autophagy via disrupting lysosome degradation may represent a novel mechanism of CsA-induced tubular epithelial cells injury.     

Role of prolyl hydroxylases 2 in the cellular response to hypoxia activated autophagy in human renal epithelial cell model

Objective To test the hypothesis of autophagy that silencing PHD2 gene could increase hypoxia inducible factor (HIF)-1α levels in the renal medulla and attenuate hypoxia injury in cultured human renal proximal tubular epithelial cell (HK-2) under cobalt dichloride (CoCl2) exposure. Methods HK-2 cells were harvested at hour 0, 6, 12, 24, 36 and 48 after exposure to CoCl2 (200 μmol/L). The role of HIF/PHD pathway in CoCl2-induced cell apoptosis/autophagy was studied by employing small-interfering RNA (siRNA). Dynamic profiles of apoptosis markers (Bax, Bcl-xl) and autophagy marker (LC3) of HK-2 cells within 48 h after exposing to CoCl2 were recorded. Alamar Blue assay was used for quantitative analysis of cellular growth and viability. Electron microscopy analysis was employed to evaluate the changes in autophagic structures. Results The protein expressions of PHD2 were gradually increased after exposing to CoCl2 (200 μmol/L), with statistics significance at 24 h and reached the peak at 48 h (both P＜0.01). PHD2 siRNA reduced PHD2 levels by＞60% and significantly increased HIF-1α protein levels (P＜0.01), but had little effect on HIF-2α. The protein expression of Bcl-xl was significantly up-regulated, while the level of Bax and LC3-Ⅱ/LC3-Ⅰ were down-regulated in PHD2 siRNA group (all P＜0.01), compared with the negative control group. Meanwhile, either 3-Methyladenine (an autophagy inhibitor) treatment or PHD2 knockdown rescued cell death and increased cell viability through autophagy inactivation. The ratio of LC3-Ⅱ/LC3-Ⅰand the quantity of autophagosomes were decreased, and the cell ultrastructure was also relatively intacter than the negative control group. Of interest, co-administration of HIF-1α siRNA with PHD2 siRNA abrogated renoprotective effect conveyed by PHD2 siRNA alone, suggesting that activation of endogenous HIF-1α-dependent pathways mediated the autophagy inactivation effects of PHD2 silencing. Conclusions Direct inhibition of PHD2 promotes renal epithelia cell survival against CoCl2-induced cell apoptosis/autophagy. Activation of the HIF-1α signaling pathway is required to reduce apoptosis and autophagy via up-regulating the expression of Bcl-xl protein.     

Survivin在紫杉醇介导MCF-7细胞凋亡中的作用

目的 观察紫杉醇对人乳腺癌细胞株MCF-7的凋亡诱导作用，探讨Survivin在此过程中的作用。方法 将不同浓度的紫杉醇作用于MCF-7细胞，噻唑蓝（MTT）比色法检测紫杉醇作用的时间效应和剂量效应；用光镜、Hoechst33258荧光染色、流式细胞仪观察细胞的凋亡变化；用逆转录一聚合酶链反应（RT-PCR）、Western blot法观察在紫杉醇作用过程中Survivin的mRNA和蛋白水平的变化。结果 细胞生长抑制率呈现一定的时间、剂量依赖性。较高浓度的紫杉醇处理MCF-7细胞48h后可观察到凋亡。而在各种浓度紫杉醇作用过程的早期（6h内），Survivin转录和蛋白表达水平明显—过性升高。结论 紫杉醇可诱导乳腺癌MCF-7细胞凋亡；而紫杉醇作用过程的早期Survivin表达的增加，极可能有利于肿瘤细胞逃避紫杉醇诱导的细胞凋亡，增加肿瘤细胞耐药的机会。     

Role of autophagy in contrast media-induced renal tubular epithelial cells injury

Objective To observe the effect of contrast media on autophagy and apoptosis of renal tubular epithelial cells, evaluate the role of autophagy in contrast media-induced renal tubular epithelial cells injury. Methods NRK-52E cells were exposed to iopromide at different concentration for 1 hour or at 50 gI/L for variable incubation time. Rapamycin (1 μg/L) and 3-methyadenine (2 mmol/L) were further introduced to investigate the role of autophagy in the process. The formation of autophagy was observed by acridine orange staining and Green fluorescent protein tagged LC3 (GFP-LC3). The expression of autophagy protein LC3 and Beclin-1 was examined by Western blotting, and the apoptosis level was examined by flow cytometry and Hoechst 33342-staining. Results (1) Autophagy could be enhanced by contrast media in renal tubular epithelial cells. (2) The expression of LC3-Ⅱ/LC3-I in renal tubular epithelial cells rose at first and then dropped with the increase of iopromide stimulation time and concentration (P＜0.05). (3) Iopromide promoted renal tubular epithelial cell apoptosis in dose-and time-dependent manner (P＜0.05). (4) Co-culture with rapamycin further increased LC3-Ⅱ/LC3-I, Beclin-1 and GFP-LC3 expression, but obviously prevented iopromide-induced apoptosis of renal tubular epithelial cells (P＜0.05). On the contrary, Co-culture with 3-methyadenine reduced iopromide-induced LC3-II/LC3-I, Beclin-1 and GFP-LC3 overexpression, but aggravated the apoptosis induced by iopromide (P＜0.05). Conclusions Contrast media can induce renal tubular epithelial cells apoptosis as well as autophagy. Enhancing autophagy appropriately has a protective effect on iopromide-induced renal tubular epithelial cells apoptosis, which conforms that autophagy plays an important role in antagonizing iopromide-induced renal tubular epithelial cells injury.