Human colon cancer cells lacking Bax resist curcumin-induced apoptosis and Bax requirement is dispensable with ectopic expression of Smac or downregulation of Bcl-XL

Multiple apoptotic stimuli induce conformational changes in Bax, a proapoptotic protein from the Bcl-2 family and its deficiency is a frequent cause of chemoresistance in colon adenocarcinomas. Curcumin, a dietary compound from turmeric, is known to induce apoptosis in a variety of cancer cells. To understand the role of Bax in curcumin-induced apoptosis we used HCT116 human colon cancer cells with one allele of Bax gene (Bax+/-) and Bax knockout HCT116 (Bax-/-) cells in which Bax gene is inactivated by homologous recombination. Cell viability decreased in a concentration-dependent manner in Bax+/- cells treated with curcumin (0-50 microM) whereas only minimal changes in viability were observed in Bax-/- cells upon curcumin treatment. In Bax-/- cells curcumin-induced activation of caspases 9 and 3 was blocked and that of caspase 8 remained unaltered. Curcumin-induced release of cytochrome c, Second mitochondria derived activator of caspase (Smac) and apoptosis inducing factor (AIF) was also blocked in Bax-/- cells and reintroduction of Bax, downregulation of the antiapoptotic protein Bcl-XL by antisense DNA as well as the overexpression of Smac, highly sensitized the Bax-/- cells toward curcumin-induced apoptosis. There was no considerable difference in the percentage of apoptotic cells in Bak RNAi transfected Bax+/- or Bax-/- cells treated with curcumin when compared with their corresponding vector transfected cells treated with curcumin. The present study demonstrates the role of Bax but not Bak as a critical regulator of curcumin-induced apoptosis and implies the potential of targeting antiapoptotic proteins like Bcl-XL or overexpression of proapoptotic proteins like Smac as interventional approaches to deal with Bax-deficient chemo-resistant cancers for curcumin-based therapy.     

Role of Bcl-2 family proteins (Bax, Bcl-2 and Bcl-X) on cellular susceptibility to radiation in pancreatic cancer cells

The aim of this study was to examine Bax, Bcl-2 and Bcl-XL proteins in human pancreatic cancer cell lines and to clarify the mechanism of radiation resistance. PANC-1 and AsPC-1 pancreatic cell lines were used, both having mutated p53. Radioresistant PANC-1/Rad cells and AsPC-1/Rad cells were obtained by repeated 5 Gy irradiation of PANC-1 cells and AsPC-1 cells, respectively. Radiation was found to inhibit the growth of PANC-1 cells and AsPC-1 cells. After exposure to radiation, detached cells were subjected to FITC-TUNEL staining to calcualte the ratio of apoptosis. TUNEL positive ratios increased dose-dependently in both cell lines. Western blotting showed that the basal level of the Bax/Bcl-2 ratio reflected the radiosensitivity of these cell lines, and Bax expression was obviously upregulated after irradiation in the presence of mutated p53, but Bcl-2 expression remained almost constant. Both PANC-1/Rad and AsPC-1/Rad cells had greater Bcl-XL expression than the parental cells, and the basal level of the Bax/Bcl-2 ratio was no longer predictive of radiosensitivity. Upregulated expression of Bax protein after irradiation was not related to induction of apoptosis in these cells, suggesting that overexpression of Bcl-XL and functional reconstruction of Bcl-2 family proteins are important factors in acquired radioresistance.     

Relative level of expression of Bax and Bcl-XL determines the cellular fate of apoptosis/necrosis induced by the overexpression of Bax.

The Bax protein plays a critical role in the apoptosis of cancers induced by radiotherapy or chemotherapy, which induce both apoptosis and necrosis. We transduced various glioblastoma cells with the Bax gene via an adenoviral vector and found that A-172 cells led to necrotic cell death, while U251 cells apoptotic cell death, even though a similar level of Bax protein was introduced. A-172 cells displayed a much higher constitutive expression of the Bcl-XL protein compared with that of U251 cells. Upon simultaneous overexpression of the Bcl-XL and Bax proteins in the U251 cells, Bax-induced apoptosis of U251 cells was suppressed and an increase in the number of necrotic cells was seen. Moreover, induction of a higher amount of Bax protein in A-172 cells increased the percentage of apoptotic cells. In conclusion, if a cancerous cell expresses a high enough amount of Bax to undergo death, apoptosis will be induced. If a cancerous cell expresses a level of Bcl-XL which prevents Bax-induced apoptosis, the overexpression of Bax leads to necrotic cell death.     

三氧化二砷对骨肉瘤细胞株MG63/dox多药耐药的逆转作用及其机制

目的 探讨三氧化二砷（As2O3）对骨肉瘤阿霉素（ADM）耐药细胞株MG63/dox的逆转作用及其机制。方法 采用不同浓度ADM（1～1000 ng／ml）和As2O3（0.25～16 μmol／L）分别单独作用于MG63和MG63/dox细胞48 h,并选取2 μmol／L As2O3联合不同浓度ADM（1～1000 ng／ml）作用于MG63/dox细胞24、48、72 h,同时设不加任何药物处理的对照组。应用CCK-8法检测两种药物对MG63和MG63／dox细胞增殖的影响,流式细胞术检测2 μmol／L As2O3、200 ng／ml ADM单独或联合处理48 h后MG63／dox细胞的周期分布和凋亡率,蛋白免疫印迹法检测2 μmol／L As2O3、200 ng／ml ADM单独或联合处理48 h后MG63／dox细胞中P-gp、Bcl-2和Bax蛋白的表达水平。结果 As2O3和ADM单药作用于MG63/dox细胞48 h,细胞增殖均未受到影响;4、8、16 μmol/L As2O3和100、200、400、500、1000 ng/ml ADM分别作用于MG63细胞48 h,细胞增殖明显受到抑制（P＜0.05）。As2O3联合ADM抑制MG63／dox细胞增殖的作用明显高于ADM单药组和对照组（P＜0.05）,且抑制作用呈时间依赖性。与对照组相比,两药联合处理组的细胞凋亡率升高,G0／G1期细胞比例降低,G2／M期细胞比例升高,以上差异均有统计学意义（P＜0.05）。两药联合处理组MG63／dox细胞中Bax蛋白表达水平明显升高,而P-gp和Bcl-2蛋白表达水平明显降低,与对照组比较,差异均有统计学意义（P＜0.05）。结论 As2O3联合ADM能够抑制骨肉瘤耐药细胞MG63／dox的增殖,这一作用可能与诱导细胞凋亡、上调Bax表达以及下调P-gp和Bcl-2表达有关。     

Efficient induction of apoptosis by doxorubicin coupled to cell-penetrating peptides compared to unconjugated doxorubicin in the human breast cancer cell line MDA-MB 231

Doxorubicin (Dox) is a commonly used drug to treat various types of cancers. Previously, we demonstrated that coupling Dox to cell-penetrating peptides (CPPs) represent a valuable strategy to overcome drug resistance in MDA-MB 231 breast cancer cells. In the present study, we evaluated the properties of these Dox conjugates (Dox–CPPs) in terms of apoptosis induction. Dox–CPPs were found to induce apoptotic death in MDA-MB 231 cells at a lower dose than that needed for unconjugated Dox. Cell death induction was associated with Bax oligomerisation, release of cytochrome c, caspase activation, chromatin condensation and internucleosomal degradation. However, whereas Bcl-2 overexpression was very potent in inhibiting apoptosis triggered by Dox, this anti-apoptotic protein was largely inefficient in preventing Dox–CPPs-induced apoptosis. These observations suggest that mitochondrial disruption is the main event in Dox-induced apoptotic signaling but that Dox–CPPs are probably able to trigger additional apoptotic pathways independent of mitochondrial events. Thus, the higher efficacy of Dox conjugated to CCPs in apoptosis induction might not be due exclusively to increased drug accumulation but also to the activation of multiple apoptotic pathways.     

Induction of apoptosis by momordin I in promyelocytic leukemia (HL-60) cells

We studied the effect of momordin I, a compound purified from a plant, Ampelopsis japonica, on cell proliferation and induction of apoptosis in human promyelocytic leukemia (HL-60) cells. Momordin I was cytotoxic to HL-60 cells with an IC50 of 19.0 microg/ml. The antiproliferative effects of momordin I appear to be attributable to its induction of apoptotic cell death, as momordin I induced nuclear morphology changes and internucleosomal DNA fragmentation and it increased the proportion of hypodiploid cells. Momordin I treatment also gradually decreased the expression of.the anti-apoptotic protein Bcl-2, but increased the expression of the pro-apoptotic protein Bax. In addition, momordin I treatment increased the activation of caspase-3 and cleavage of poly (ADP-ribose) polymerase. In this study we showed that momordin I induced apoptosis of HL-60 cells by reduction of the Bcl-2:Bax ratio and by activation of caspase-3. These results provide important information towards understanding the mechanism by which momordin I induces apoptosis.     

Resistance to diverse apoptotic triggers in multidrug resistant HL60 cells and its possible relationship to the expression of P-glycoprotein, Fas and of the novel anti-apoptosis factors IAP (inhibitory of apoptosis proteins)

We studied the human HL60 leukemia cell line and its multidrug resistant (MDR) variant HL60R. In contrast to the HL60, HL60R showed an inability to undergo apoptosis from doxorubicin (Dox) or other different stimuli, including cisplatin, Fas ligation and serum withdrawal. HL60R cells lost surface Fas expression, but we found no evidence that Fas/FasL mediates the apoptotic effects of Dox in HL60. P-glycoprotein (P-gp) did not seem to play a major role as a specific inhibitor of apoptosis. In fact, the P-gp inhibitor verapamil reversed only partially the resistance to Dox-induced apoptosis of the MDR cells. In addition, it did not modify the rate of apoptosis induced from the other stimuli in the same cells. The expression of p53 or Bcl-2 was not different between HL60 and HL60R. However, in HL60R there was an increase in the mRNAs of inhibitory of apoptosis proteins (IAPs) like neuronal apoptosis inhibitory protein (NAIP), c-IAP-2 and survivin. Treatment with Dox or serum starvation strongly down-regulated X-linked IAP and survivin mRNAs in HL60. Cisplatin decreased NAIP and survivin mRNAs in the same cells. However, in HL60R the levels of these IAP mRNAs were much less affected by the treatments. These results support that IAPs may be involved in tumor resistance to chemotherapeutic drugs or other apoptotic agents.     

The cytotoxicity of Scytosiphon lomentaria against HL-60 promyelocytic leukemia cells

This study examined the cytotoxicity of Scytosiphon lomentaria, using various cancer cell lines. The ethyl acetate (EtOAc) fraction of this alga showed the cytotoxicity to leukemia cells, including HL-60. When HL-60 cells were treated with its EtOAc fraction, several apoptotic characteristics, such as DNA fragmentation, chromatin condensation, and an increase of the population of sub-G1 hypodiploid cells, were observed. Moreover, the EtOAc fraction decreased c-Myc expression in a dose-dependent manner. In order to understand the mechanism of apoptosis induction by S. lomentaria, we examined the changes of Bcl-2 and Bax protein expression levels. The EtOAc fraction reduced Bcl-2, an antiapoptotic protein, but increased Bax, a proapoptotic protein, in a dose-dependent manner. When we examined the activation of caspase-3, an effector of apoptosis, the expression of the active form (19 kDa) of caspase-3 increased, and the increase of their activities was demonstrated by the cleavage of poly (ADP-ribose) polymerase, a substrate of caspase-3, to 85 kDa. The results suggest that the inhibitory effect of S. lomentaria on the growth of HL-60 appears to arise from the induction of apoptosis by way of the down-regulation of Bcl-2 and the activation of caspase.     

Resveratrol inhibits cell proliferation and induces apoptosis of human breast carcinoma MCF-7 cells

Resveratrol, which is found in grapes and wine, has been reported to have a variety of important pharmacological effects including anti-inflammatory, anti-platelet, and anti-carcinogenetic properties. In this study, using the human breast cancer cell line MCF-7, we have analyzed a possible mechanism by which resveratrol could interfere with cell cycle control and induce cell death. Resveratrol treatment of MCF-7 cells resulted in a dose-dependent inhibition of the cell growth and the cells accumulated at the S phase transition of the cell cycle at low concentrations, but high concentrations do not induce S phase accumulation. The anti-proliferative effects of resveratrol were associated with a marked inhibition of cyclin D and cyclin-dependent kinase (Cdk) 4 proteins, and induction of p53 and Cdk inhibitor p21WAF1/CIP. Growth suppression by resveratrol was also due to apoptosis, as seen by the appearance of a sub-G1 fraction and chromatin condensation. In addition, the apoptotic process involves activation of caspase-9, a decrease of Bcl-2 as well as Bcl-XL levels, and an increase of Bax levels.     

Upregulation of Bfl-1/A1 in leukemia cells undergoing differentiation by all-trans retinoic acid treatment attenuates chemotherapeutic agent-induced apoptosis.

All-trans retinoic acid (ATRA) induces differentiation of NB4 and HL-60 leukemia cells, but not R4 and HL-60/Res cells. Three agents used in cancer therapy, doxorubicin (Dox), arsenic trioxide (As(2)O(3)) and paclitaxel, induce apoptosis, but not differentiation, in all of these cell lines. The induction of apoptosis by these agents is decreased in ATRA-pretreated NB4 and HL-60 cells, but not in ATRA-pretreated R4 and HL-60/Res cells. The level of Bcl-2 protein is decreased by ATRA treatment in NB4, HL-60 and HL-60/Res cells. The level of Mcl-1 protein is increased by ATRA treatment in NB4 and R4 cells, but not in HL-60 and HL-60/Res cells. Bfl-1/A1 mRNA is not expressed in these cell lines, however, its expression is markedly induced by ATRA treatment in NB4 and HL-60 cells, but not in R4 or HL-60/Res cells, which correlates with inhibition of apoptosis. Inhibiting Bfl-1/A1 mRNA upregulation in ATRA-pretreated NB4 cells using small interfering RNA (siRNA) partly recovers cell sensitivity to Dox-induced apoptosis. These data demonstrate that ATRA induction of Bfl-1/A1 in differentiated NB4 and HL-60 cells contributes to a loss of sensitivity to chemotherapy-induced apoptosis.     

Anti-hepatoma cells function of luteolin through inducing apoptosis and cell cycle arrest

The aim of this study is to explore the apoptotic induction and cell cycle arrest function of luteolin on the liver cancer cells and the related mechanism. The liver cancer cell line SMMC-7721, BEL-7402, and normal liver cells HL-7702 were treated with different concentrations of luteolin. Cell proliferation ability was tested. Morphological changes of the apoptotic cells were observed under inverted fluorescence microscope after Hoechst33342 staining. We investigated the effect of luteolin on cell cycling and apoptosis with flow cytometry. The mitochondrial membrane potential changes were analyzed after JC-1 staining. Caspases-3 and Bcl-2 family proteins expression were analyzed by real-time PCR. Cell proliferation of SMMC-7721 and BEL-7402 were inhibited by luteolin, and the inhibition was dose–time-dependent. Luteolin could arrest the cells at G1/S stage, reduce mitochondrial membrane potential, and induce higher apoptosis rate and the typical apoptotic morphological changes of the liver carcinoma cells. Q-RT-PCR results also showed that luteolin increased Bax and caspase-3 expression significantly and upregulated Bcl-2 expression in a dose-dependent manner in liver carcinoma cells. However, the normal liver cells HL-7702 was almost not affected by luteolin treatment. Luteolin can inhibit SMMC-7721 and BEL-7402 cell proliferation in a time- and dose-dependent manner. And the mechanism maybe through arresting cell cycle at phase G1/S, enhancing Bax level, reducing anti-apoptotic protein Bcl-2 level, resulting in activating caspase-3 enzyme and decrease of mitochondrial membrane potential, and finally leading to cell apoptosis.     

三氧化二砷和曲古抑菌素A协同诱导HL-60细胞凋亡的作用及分子机制研究

目的 探讨三氧化二砷(As2O3)和曲古抑菌素A(TSA)在体外诱导急性早幼粒白血病细胞HL-60凋亡过程中的协同作用.方法 采用MTT法检测As2O3和(或)TSA对HL-60细胞增殖的影响,流式细胞术检测细胞周期和细胞凋亡,逆转录-聚合酶链反应(RT-PCR)检测凋亡相关基因Bax和Bcl-2的表达.结果 As2O3和TSA联用较单独用药能明显抑制细胞,引起细胞周期阻滞和凋亡,Bax基因表达升高,Bcl-2基因表达降低,Bax/Bcl-2比值升高.结论 As2O3和TSA均能够引起HL-60凋亡,二者具有协同效应,其机制是引起细胞周期阻滞,且上调Bax与Bcl-2比值.     

PML-RARα表达对细胞凋亡诱导剂敏感性差异的分子机制研究

目的 研究PML-RARα表达阴性的HL-60细胞和表达阳性的NB4细胞对三氧化二砷(As2O3)诱导细胞凋亡敏感性差异的分子机制.方法 经As2O3作用人急性早幼粒细胞白血病HL-60和NB4细胞后,MTT法检测细胞增殖变化,流式细胞术测定细胞凋亡水平的变化,RT-PCR检测Bcl-2、Bax、Fas等基因在mRNA水平的表达变化.结果 As2O3可诱导NIM细胞出现明显的凋亡现象,细胞增殖受到明显抑制(P<0.05),Bcl-2基因表达明显下调(P<0.05),但Bax、Fas基因表达没有明显变化(P>0.05),Bcl-2/Bax比值明显降低(P<0.05).而对于PML-RARa表达阴性的HL-60细胞,经小剂量As2O3作用后,对细胞的增殖抑制作用不明显(P>0.05),未出现明显凋亡现象,Bcl-2、Bax、Fas或Bcl-2/Bax表达水平及比值变化不明显(P>0.05).结论 Bcl-2/Bax表达比值变化与否,可能是小剂量As2O3诱导PML-RARα表达阴性的HL-60细胞和表达阳性的NB4细胞发生凋亡差异的分子机制.     

Coriolus versicolor (Yunzhi) extract attenuates growth of human leukemia xenografts and induces apoptosis through the mitochondrial pathway

Coriolus versicolor (CV), also called Yunzhi, has been demonstrated to exert anti-tumor effects on various types of cancer cells. Our previous studies have demonstrated that a standardized aqueous ethanol extract prepared from CV inhibited the proliferation of human leukemia cells via induction of apoptosis. The present study aimed to evaluate the underlying mechanisms of apoptosis through modulation of Bax, Bcl-2 and cytochrome c protein expressions in a human pro-myelocytic leukemia (HL-60) cell line, as well as the potential of the CV extract as anti-leukemia agent using the athymic mouse xenograft model. Our results demonstrated that the CV extract dose-dependently suppressed the proliferation of HL-60 cells (IC50 = 150.6 microg/ml), with increased nucleosome production from apoptotic cells. Expression of pro-apoptotic protein Bax was significantly up-regulated in HL-60 cells treated with the CV extract, especially after 16 and 24 h. Meanwhile, expression of anti-apoptotic protein Bcl-2 was concomitantly down-regulated, as reflected by the increased Bax/Bcl-2 ratio. The CV extract markedly, but transiently, promoted the release of cytochrome c from mitochondria to cytosol after 24-h incubation. In vivo studies in the athymic nude mouse xenograft model also confirmed the growth-inhibitory activity of the CV extract on human leukemia cells. In conclusion, the CV extract attenuated the human leukemia cell proliferation in vivo, and in vitro possibly by inducing apoptosis through the mitochondrial pathway. The CV extract is likely to be valuable for the treatment of some forms of human leukemia.     

DADS通过MAPK和PI3K/Akt 信号通路下调Mcl-1诱导白血病细胞凋亡*

目的:二烯丙基二硫（DADS）为天然植物大蒜中的提取物,能抑制多种肿瘤细胞生长,本文探讨丝裂原激活的蛋白激酶（MAPKs）、3- 磷酸肌醇激酶（PI 3K/Akt）信号通路和Bcl- 2 家族成员在DADS诱导的人白血病HL- 60细胞凋亡中的作用。方法:利用流式细胞术检测DADS 诱导的白血病细胞凋亡,Western blot研究MAPKs和PI 3K/Akt信号通路在DADS 诱导的人白血病HL- 60细胞凋亡中的变化及对Bcl- 2 家族凋亡相关蛋白表达的影响。结果:DADS呈浓度和时间依赖性地诱导人白血病HL- 60细胞凋亡,在此过程中ERK/MAPK 和PI 3K/Akt信号通路被抑制,而p38MAPK 信号通路被激活,ERK/MAPK 和PI 3K/Akt信号通路通过降低Mcl-1（myeloid cell leukemia-1）和升高Bax 的表达诱导人白血病细胞凋亡,而p38MAPK 则不是通过调控Mcl-1 和Bax 的表达诱导人白血病细胞凋亡,进一步利用RNA干扰技术沉默Mcl-1 基因可增加DADS对HL- 60细胞增殖抑制和诱导凋亡作用。结论:MAPK 和PI 3K/Akt信号通路通过下调Mcl-1 的表达参与了DADS诱导的HL- 60细胞凋亡作用。      

The newly synthesized 2-(3-hydroxy-5-methoxyphenyl)-6,7-methylenedioxyquinolin-4-one triggers cell apoptosis through induction of oxidative stress and upregulation of the p38 MAPK signaling pathway in HL-60 human leukemia cells

The aim of the present study was to discover the signaling pathways associated with 2-(3-hydroxy-5-methoxy-phenyl)-6,7-methylenedioxyquinolin-4-one (YYK1)-induced apoptosis in HL-60 human leukemia cells. YYK1 induced cytotoxic effects, cell morphological changes, decreased the cell number and increased reactive oxygen species (ROS) production and loss of mitochondrial membrane potential (ΔΨm) in HL-60 cells. YYK1-induced apoptosis was confirmed by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. Results from colorimetric assays and western blot analysis indicated that activities of caspase-7/-3, caspase-8 and caspase-9 were increased in YYK1-treated HL-60 cells. Western blot analysis showed that the protein levels of extrinsic apoptotic proteins (Fas/CD95, FasL and FADD), intrinsic related proteins (cytochrome c, Apaf-1, AIF and Endo G), the ratio of Bax/Bcl-2 and phosphorylated p38 MAPK were increased in HL-60 cells after YYK1 treatment. Cell apoptosis was significantly reduced after pre-treatment with N-acetylcysteine (NAC; a ROS scavenger) or diphenyleneiodonium chloride (DPI; a NADPH oxidase inhibitor). Blockage of p38 MAPK signaling by SB202190 abolished YYK1-induced Fas/CD95 upregulation and apoptosis in HL-60 cells. We conclude that YYK1 induces both of extrinsic and intrinsic apoptotic pathways via ROS-mediated activation of p38 MAPK signaling in HL-60 human leukemia cells in?vitro.     

Antiproliferation effects of ponicidin on human myeloid leukemia cells in vitro

Ponicidin, an extract from the Chinese herb Rabdosia rubescens, is currently one of the most important traditional Chinese herbal medicines. Ponicidin has been reported to have anti-tumor effects on a large variety of malignant diseases. In this study, we investigated the anti-proliferation effects of ponicidin on human myeloid K562 and HL-60 cells. Cell viability was measured by MTT assay; cell apoptosis was assessed by flow cytometry, DNA fragmentation analysis and Hoechst 33258 staining. Caspase-3 and poly(ADP-ribose) polymerase (PARP) activation and Bax and Bcl-2 expression were detected by Western blot analysis. The results revealed that ponicidin could significantly inhibit the growth of K562 and HL-60 cells by induction of apoptosis. The suppression was both time- and dose-dependent. Cell apoptosis was observed clearly after the cells were treated with ponicidin for 48-72 h. Western blotting showed cleavage of the caspase-3 zymogen protein (32 kDa) with the appearance of its 17 kDa subunit, together with a cleaved 89-kDa fragment of 116 kDa PARP when apoptosis occurred. Bcl-2 expression was down-regulated while Bax expression up-regulated concurrently when the cells were treated with ponicidin for 24-48 h. Therefore, we conclude that ponicidin has significant anti-proliferation effects by induction of apoptosis on myeloid leukemia cells in vitro, down-regulation of Bcl-2, and up-regulation of Bax, and that activation of caspase-3 and PARP may be an important apoptosis-inducing mechanism. The results suggest that ponicidin may serve as a potential therapeutic agent for leukemia.     

维泰醇对小鼠宫颈癌U14细胞抗肿瘤作用的研究

目的:研究维泰醇对宫颈癌U14细胞的抑制增殖与诱导凋亡作用,以探讨维泰醇的抗肿瘤作用机制。方法:采用MTT法检测维泰醇对宫颈癌U14细胞增殖抑制率的影响;采用AO/EB双染色法观察细胞凋亡形态并计算其凋亡率;免疫细胞化学法检测U14细胞内Bcl-2,Bax、Survivin蛋白表达水平。结果:维泰醇对U14细胞增殖有明显的抑制作用,呈剂量及时间依赖性;维泰醇能引起细胞凋亡,并出现典型的凋亡形态。维泰醇下调U14细胞内Bcl-2、Survivin蛋白表达水平,上调Bax蛋白表达水平。结论:维泰醇可抑制宫颈癌U14细胞增殖并诱导细胞凋亡;维泰醇抗宫颈癌的作用机制可能与其下调Bcl-2、Survivin蛋白的表达及上调Bax蛋白的表达有关。     

千金子甾醇诱导HL-60细胞凋亡机制研究

目的探讨Bcl-2/Bax信号通路在千金子甾醇诱导HL-60白血病细胞发生凋亡中的作用及其分子机制研究。方法HL-60细胞培养体系中分别加入大、中、小剂量千金子甾醇溶液,甾醇溶液作用细胞24h后,采用CCK-8法检测千金子甾醇对HL-60细胞增殖的抑制作用,光镜下观察细胞形态学变化,AnnexinⅤ/PI流式细胞术检测细胞凋亡,RT-PCR法检测Bcl-2/Bax、Caspase-9和Caspase-3mRNA转录水平,ELISA法检测Caspase-9和Caspase-3蛋白活性。结果 CCK-8法检测结果显示,与对照组比较,千金子甾醇能明显抑制HL-60细胞增殖（F=42.97,P〈0.001）,各个浓度之间进行比较,差异有统计学意义,P〈0.05。流式细胞术检测细胞凋亡率显著增加（F=56.74,P〈0.001）,经10、20和40μg/mL千金子甾醇处理24h后,HL-60细胞早期凋亡率分别为（23.4±3.1）%、（35.7±4.3）%和（53.2±3.9）%,细胞呈典型凋亡形态学改变。千金子甾醇作用后,Bax mRNA转录水平显著升高,Bcl-2mRNA转录水平显著降低,且呈化合物剂量依赖性（F=53.45,P〈0.001）,Caspase-9和Caspase-3 mRNA转录水平升高,且呈化合物剂量依赖性（F=34.21,P〈0.001）,千金子甾醇对HL-60细胞作用24h后Caspase-9和Caspase-3蛋白活性显著升高（F=54.33,P〈0.001）,且随着千金子甾醇浓度增加蛋白活性逐渐升高。结论千金子甾醇通过调节Bcl-2/Bax凋亡信号通路,诱导HL-60细胞凋亡,其作用呈明显剂量依赖性。