Increased expression of phospho-acetyl-CoA carboxylase protein is an independent prognostic factor for human gastric cancer without lymph node metastasis

Triptolide is a traditional Chinese medicinal herb-derived antineoplastic agent. However, its antitumor activity against gynecologic carcinomas has not yet been well described. It is the purpose of this article to investigate the effect and mechanism of triptolide in human ovarian cancer using both A2780 (p53 wild) and OVCAR-3 (p53 mutated) cells. Our results showed that triptolide exerted a potent inhibitory effect on the growth and proliferation of both cell lines in a dose- and time-dependent manner and that the effect was independent of the expression of p53. In contrast, triptolide had only a marginal cytotoxicity in noncancerous ovary cells, lung fibroblast cells, and macrophage cells, indicating differential inhibitory effects of the drug on cell growth between ovarian cancer cells and normal tissue cells. Exposure of the ovarian cancer cells to triptolide induced apoptosis, as evaluated by annexin V/propidium iodide-labeled flow cytometry. Triptolide-induced apoptosis was accompanied by cytochrome c release and caspase-3 activation and was associated with downregulation of Bcl-2 and upregulation of Bax. Cell cycle analysis demonstrated that treatment with triptolide induced cell cycle S phase arrest in A2780 cells and G2/M phase arrest in OVCAR-3 cells. Further detection by Western blotting revealed that the cell cycle arrest by triptolide in both cell lines occurred in concert with increased expression of p21^CIP1/WAF1. This study shows that triptolide selectively kills ovarian cancer cells with different p53 status predominantly through regulating the coordinate and dynamic cellular processes of proliferation and apoptosis, thereby making it a promising chemotherapeutic agent against a broad spectrum of ovarian carcinomas.     

Caspase-3 Activation Is Not Responsible for Vinblastine-induced Bcl-2 Phosphorylation and G2/M Arrest in Human Small Cell Lung Carcinoma Ms-1 Cells

Vinblastine arrests cells in the G2/M phase of the cell cycle and subsequently induces cell death by apoptosis. We found that treatment of cells with vinblastine induced phosphorylation of Bcl-2, resulting in the dissociation of Bcl-2 and Bax. Moreover, vinblastine-induced apoptosis was suppressed by an inhibitor of caspase-3, Ac-DEVD-CHO; and a 17-kDa active fragment of caspase-3 was detected following vinblastine treatment, suggesting that caspase-3 is involved in vinblastine-induced apoptosis. However, Ac-DEVD-CHO affected neither vinblastine-induced Bcl-2 phosphorylation nor vinblastine-induced G2/M arrest. Vinblastine caused G2/M arrest prior to apoptosis, whereas vinblastine-induced apoptosis was not dependent on the duration of the G2/M phase. Thus, vinblastine-induced apoptosis might be mediated by the phosphorylation of Bcl-2, resulting in Bcl-2 inactivation, and by subsequent activation of caspase-3.     

Cochinchina momordica seed extract induces G2/M arrest and apoptosis in human breast cancer MDA-MB-231 cells by modulating the PI3K/Akt pathway

Cochinchina momordica seeds are a kind of traditional Chinese herb. In this study, anticancer activity and underlying mechanisms were investigated with an extract using human breast cancer MDA-MB-231 cells. The survival rate was reduced in a concentration- and time-dependent manner as assessed by MTT assay. After incubation for 48 h, typical apoptotic morphological changes were observed by Hoechst 33258 dye assay. Flow cytometry revealed that the treatment obviously induced G2/M arrest and apoptosis in MDA-MB-231 cells. Furthermore, western blotting demonstrated downregulation of protein expression of PI3K, Akt, NF-kB, Bcl-2, Cdk1 and cyclin B1, whereas Bax and caspase-3 were upregulated. Our results suggest that the extract induced cell cycle G2/M arrest and apoptosis in MDA-MB-231 cells by decreasing PI3K/Akt pathway. Therefore, we propose that ECMS has potential as a breast cancer chemotherapeutic agent.     

Induction of apoptosis and G2/M cell cycle arrest by DCC.

The Deleted in Colorectal Cancer gene (DCC) encodes a cell surface receptor that belongs to the Ig superfamily. Inactivation of the DCC gene has been implicated in human tumor progression. However, little is known about the biological function of the DCC protein. In the present study, we demonstrated that expression of DCC activated caspase-3 and programmed cell death, or induced G2/M cell cycle arrest in tumor cells. In some cell lines, apoptosis was evident within 24 h of DCC expression. Timing of the appearance of apoptotic cells coincided with that of the cleavage of poly (ADP-ribose) polymerase, a substrate of caspase-3. Expression of the apoptosis inhibitory gene Bcl-2 was not able to abrogate the DCC-induced apoptosis. In the G2/M cycle arrest cells, cdk1 activity was inhibited. Our results suggest that the DCC protein may transduce signals resulting in activation of caspases or inhibition of Cdk1. These data provide a possible mechanism by which DCC suppresses tumorigenesis.     

The histone deacetylase inhibitor trichostatin A induces cell cycle arrest and apoptosis in colorectal cancer cells via p53-dependent and -independent pathways

Many chemotherapeutic agents induce apoptosis via a p53-dependent pathway. However, up to 50% of human cancers have p53 mutation and loss of p53 function. Histone deacetylase inhibitors (HDACIs) are emerging as a potentially important new class of anticancer agents. Here, we report that, Trichostatin A (TSA), a pan-HDAC inhibitor, could induce G2/M cell cycle arrest and apoptosis in both colorectal cancer cell lines with wild-type p53 (HT116 cells) and mutant p53 (HT29 cells), although HCT116 cells had more apoptotic cells than HT29 cells. TSA induces apoptosis in both cell lines via the mitochondrial pathway as indicated by decrease of the mitochondrial membrane potential (MMP) and activation of caspase-3. Additionally, TSA induces expression of the pro-apoptotic protein Bax and decreases the expression of the anti-apoptotic proteins Bcl-2 and Bcl-xL in both cell lines. Bax knockdown by siRNA significantly impaired TSA-induced apoptosis in both cell lines. These data suggest that TSA induces G2/M cell cycle arrest and Bax-dependent apoptosis in colorectal cancer cells (HCT116 cells and HT29 cells) by both p53-dependent and -independent mechanisms. However, cells with normal p53 function are more sensitive to TSA-induced apoptosis.     

Protoapigenone, a novel flavonoid, inhibits ovarian cancer cell growth in vitro and in vivo

Flavonoids are polyphenolic compounds and capable of inhibiting the growth of human cancer cells. Protoapigenone, a novel flavonoid, was isolated from the whole plant Thelypteris torresiana (Gaud), a native fern in Taiwan. In the present study, we explored the cytotoxic effects of protoapigenone on ovarian cancer cells and the immortalized ovarian epithelial cells by XTT assay. The effects of protoapigenone on cell cycle progression and apoptosis were also analyzed by FACS analysis, immunofluorescence study and immunoblotting analysis. The anti-ovarian cancer effect of protoapigenone was further examined using nude mice xenograft assay and immunohistochemistry. Our results showed that protoapigenone had a significant cytotoxicity on human ovarian cancer cells MDAH-2774 and SKOV3 but not on the immortalized non-cancer ovarian epithelial cells HOSE 6-3 and HOSE 11-12. Protoapigenone arrested MDAH-2774 and SKOV3 cells at S and G2/M phases via decreasing the expression of p-Cdk2, Cdk2, p-Cyclin B1 and Cyclin B1, as well as increasing the expression of inactive p-Cdc25C. Besides, protoapigenone had an enhanced cytotoxicity on SKOV3 cells enriched at S and G2/M phases, and ability to induce apoptosis through decreasing the protein levels of Bcl-xL and Bcl-2 and increasing the cleaved PARP by activating caspase-3. In nude mice study, protoapigenone treatment significantly suppressed the tumor growth, without major side effects. Taken together, protoapigenone showed a significant anti-ovarian cancer activity with low toxicity, suggesting its potential to be developed as a chemotherapeutic agent.     

Caspase-mediated Cdk2 activation is a critical step to execute transforming growth factor-beta1-induced apoptosis in human gastric cancer cells

Although TGF-beta1, a growth inhibitor, is known to also induce apoptosis, the molecular mechanism of this apoptosis is largely undefined. Here, we identify the mechanism of TGF-beta1-induced apoptosis in SNU-16 human gastric cancer cells. Cell cycle and TUNEL analysis showed that, upon TGF-beta1 treatment, cells were initially arrested at the G1 phase and then driven into apoptosis. Of note, caspase-3 was activated in accordance with TGF-beta1-induced G1 arrest. Activated caspase-3 is targeted to cleave p21(cip1), p27(kip1), and Rb, which play important roles in TGF-beta-induced G1 arrest, into inactive fragments. Subsequently, Cdk2 was aberrantly activated due to the cleavage of p21 and p27. We found that the inhibition of Cdk2 activity efficiently blocks TGF-beta1-induced apoptosis, whereas it did not prevent caspase-3 activation or the subsequent cleavage of target proteins. In contrast, the suppression of caspase-3 activity inhibited the cleavage of target proteins, the activation of Cdk2, and the induction of apoptosis. Taken together, our results suggest that activation of caspase-3 by TGF-beta1 may initiate the conversion from G1 cell cycle arrest to apoptosis via the cleavage of p21, p27 and Rb, which in turn causes Cdk2 activation and, most significantly, Cdk2 activation as a downstream effector of caspase is a critical step for the execution of TGF-beta1-induced apoptosis.     

Piperine induces apoptosis of lung cancer A549 cells via p53-dependent mitochondrial signaling pathway

The aim of this study was to evaluate the cytotoxic and apoptotic effects of piperine on human lung cancer A549 cells and to explore its mechanisms. Piperine was found to exert the greatest cytotoxic effect against A549 cells in a dose-dependent manner, whereas it showed no effect on WI38 human lung fibroblasts. This cell growth-inhibitory effect might be attributed to cell DNA damage and cytotoxic effects. Besides, piperine had the ability to cause cell cycle arrest in G2/M phase and to activate caspase-3 and caspase-9 cascades in A549 cells. Furthermore, piperine-induced apoptosis could be blocked by the broad caspase inhibitor z-VAD-fmk in majority. In addition, piperine treatment decreased Bcl-2 protein expression, but increased Bax protein expression in A549 cells, which were positively correlated with an elevated expression of p53 compared to control. Taken together, these results suggested that piperine could induce p53-mediated cell cycle arrest and apoptosis via activation of caspase-3 and caspase-9 cascades, as well as increasing the Bax/Bcl-2 ratio. Thus, piperine could be developed as an effective antitumor agent in the prevention and treatment of lung cancer without toxicity to the host.     

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.     

Apoptotic death in curcumin-treated NPC-TW 076 human nasopharyngeal carcinoma cells is mediated through the ROS, mitochondrial depolarization and caspase-3-dependent signaling responses

Curcumin, a potent candidate anticancer agent, is a dietary pigment (phenolic compound) derived from the food flavoring spice turmeric (Curcuma longa), and it has been shown to have inhibitory effects on tumor cells through anti-proliferative and proapoptotic activities. However, there is no report showing curcumin-induced apoptotic cell death in human nasopharyngeal carcinoma cells in vitro. Thus, this study was performed to elucidate whether mitochondria and caspase cascades are involved in the modulation of apoptosis and cell cycle arrest in curcumin-treated NPC-TW 076 human nasopharyngeal carcinoma cells. The effects of curcumin on cell cycle arrest and apoptosis were measured by flow cytometry, and caspase-3 activity, apoptosis-associated protein levels and its regulated molecules were studied by flow cytometric assay and immunoblots. The results indicated that curcumin-induced G2/M phase arrest was associated with a marked decrease in the protein expression of cyclin A, cyclin B and cyclin-dependent kinase 1 (Cdk1). Curcumin-induced apoptosis was accompanied with upregulation of the protein expression of Bax and downregulation of the protein levels of Bcl-2, resulting in dysfunction of mitochondria and subsequently led to cytochrome c release and sequential activation of caspase-9 and caspase-3 in NPC-TW 076 cells in a time-dependent manner. These findings revealed that mitochondria, AIF caspase-3- dependent pathways play a vital role in curcumin-induced G2/M phase arrest and apoptosis of NPC-TW 076 cells in vitro.     

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.     

Platycodin D,a triterpenoid saponin from Platycodon grandiflorum,induces G2/M arrest and apoptosis in human hepatoma HepG2 cells by modulating the PI3K/Akt pathway

Platycodin D (PD) is one of triterpenoid saponins isolated from the roots of Platycodon grandiflorum. In the present study, we aimed at examining the antitumor activity of PD against human hepatoma HepG2 cancer cells and investigated the underlying molecular mechanisms of PD-induced apoptosis in HepG2 cells. PD significantly inhibited the proliferation of HepG2 cells in a concentration- and time-dependent manner as assessed by MTT assay. Besides, flow cytometry revealed that PD treatment obviously induced G2/M arrest and apoptosis in HepG2 cells. Moreover, Western blot analysis demonstrated that PD induced downregulation of protein expression of PI3K, P-Akt, and Bcl-2, whereas cleaved products of caspase-3 and ?9 and PARP were upregulated by PD treatment. Furthermore, the protein level of P-p38, p-38, and Bax in PD-treated HepG2 cells was kept unchanged. In addition, the inhibitors of z-DEVD-fmk (a specific caspase-3 inhibitor) and z-LEHD-fmk (a specific caspase-9 inhibitor), but not z-IETD-fmk (a specific caspase-8 inhibitor), could significantly block PD-triggered apoptosis, whereas LY294002 (Akt inhibitor) could significantly enhance PD-induced apoptosis in HepG2 cells. Thus, the increasing ratio of Bax to Bcl-2, activation of caspase-3 and ?9 and PARP, and inactivation of the PI3K/Akt signaling pathway significantly enhanced PD-induced apoptosis in HepG2 cells. Our results suggest that PD induced cell cycle G2/M arrest and apoptosis in HepG2 cells by decreasing PI3K/Akt pathway. Therefore, we propose that PD has potential as a liver cancer chemotherapeutic agent.     

Suppression of human prostate cancer cell growth by ciprofloxacin is associated with cell cycle arrest and apoptosis

For hormone resistant prostate cancer (HRPC), chemotherapy is used but the mortality is 100% with a mean survival time of 7-8 months. Our previous studies have shown the chemotherapeutic effect of ciprofloxacin in bladder cancer. At doses 50-400 micro g/ml ciprofloxacin, the concentrations that are normally achieved at doses currently used for the treatment of anti-bacterial infections, inhibited bladder cancer cell growth and induced S/G2M arrest with modulation of key cell cycle regulatory genes and ultimately activated apoptotic processes. In this study, we investigated the effect of ciprofloxacin on androgen independent prostate carcinoma, PC3 cells and compared our results with non-tumorigenic prostate epithelial cells. The main advantage of this fluroquinolone antibiotic is its relative non-toxicity as compared to current chemotherapy, which is not very effective, for the treatment of advanced hormone resistant prostate cancer. PC3 cells as well as normal prostate epithelial cells (MLC8891) were treated with 25-400 micro g/ml ciprofloxacin, and cell counting was done during 3 days of treatment. The cell death was determined using DAPI staining of cell nuclei, 7AAD-staining followed by flow cytometric analysis as well as by activation of caspase-3, a member of the ICE family of enzymes involved in the apoptotic cascade. The cell lysates were analyzed by immunoblotting techniques for the expression of key genes targeted by ciprofloxacin (p21WAF1, Bax and Bcl-2). Translocation of bax was visualized using a fluorescence staining procedure followed by laser confocal microscopic imaging. Treatment of prostate cancer cells with ciprofloxacin resulted in a dose- and time-dependent inhibition of cell growth (70-100% with 50-400 micro g/ml of the drug). There was a concomitant induction of cell cycle arrest at the S and G2/M phases of the cell cycle as well as induction of apoptosis. The CDK inhibitor p21WAF1 was down-regulated as early as 12 h following ciprofloxacin treatment (100-200 micro g/ml for 12-24 h). There was a significant increase in the Bax/Bcl-2 ratio with translocation of Bax, a pro-apoptotic protein, to mitochondria with concomitant activation of caspase 3. These results suggest the potential usefulness of the fluroquinolone, ciprofloxacin as a chemotherapeutic agent for advanced prostate cancer. The fluroquinolone ciprofloxacin showed anti-proliferative and apoptosis inducing activity on prostate cancer cells but not on non-tumorigenic prostate epithelial cells. These effects of ciprofloxacin were mediated by cell cycle arrest at S-G2/M phase of the cell cycle, Bax translocation to mitochondrial membrane and by increasing the Bax/Bcl-2 ratio in PC3 prostate cancer cells. Based on our in vitro results, further in-depth in vivo animal or human investigations are warranted.     

Gypenosides induced G0/G1 arrest via CHk2 and apoptosis through endoplasmic reticulum stress and mitochondria-dependent pathways in human tongue cancer SCC-4 cells

Gypenosides (Gyp), a component of Gynostemma pentaphyllum Makino, was selected for examining the effects on the cell viability, cell cycle and induction of apoptosis in human tongue cancer SCC-4 cells. Gyp induced cytotoxicity (decreased the percentage of viable cells) in SCC-4 cells appeared to be associated with induction of cell cycle arrest (G0/G1 arrest), apoptotic cell death based on Gyp induced morphological changes and DNA fragmentation and increased the sub-G1 group in examined SCC-4 cells. The production of reactive oxygen species and Ca(2+) and the depolarization of mitochondrial membrane potential were observed, dose- and time-dependently, after treatment of SCC-4 cells with various concentrations of Gyp. Gyp inhibited the levels of the anti-apoptotic proteins Bcl-2 and Bcl-xl, but promoted the levels of the pro-apoptotic protein Bax. Western blotting showed the releases of cytochrome c and Endo G and both were also confirmed by confocal laser microscopic systems. The GADD153 moved to nuclei (nuclear translocation). In conclusion, Gyp induced ER stress and production of reactive oxygen species and Ca(2+), change the ratio of Bcl-2 and Bax, followed by the dysfunction of mitochondria, caused cytochrome c release, activation of caspase-3 before leading to apoptosis. These results provide information towards an understanding of the mechanisms by which Gyp induces cell cycle arrest and apoptosis in human tongue cancer cells.     

下调fascin抑制卵巢癌细胞从G0/G1期向S期转变的实验研究

目的:研究下调聚束蛋白（fascin）对卵巢癌细胞周期、增殖和凋亡的影响。方法:卵巢癌细胞SKOV3感染阴性对照慢病毒载体、shRNA fascin 1慢病毒载体、shRNA fascin 2慢病毒载体，用Real-time PCR和Western blot检测干扰效果。MTT检测增殖活性，克隆形成实验检测细胞克隆形成能力，流式细胞术检测细胞周期和细胞凋亡，Western blot检测细胞中活化型Caspase-3（Cleaved Caspase-3）、细胞周期依赖性蛋白激酶4(cyclin-dependent kinase 4，Cdk4)、活化型Caspase-9（Cleaved Caspase-9）和p21蛋白水平。结果:shRNA fascin 1慢病毒载体、shRNA fascin 2慢病毒载体感染后的SKOV3细胞中fascin mRNA和蛋白表达水平均降低，并且shRNA fascin 1慢病毒载体感染后细胞中fascin mRNA和蛋白表达水平下降更多。下调fascin后的卵巢癌细胞增殖能力降低，细胞克隆形成能力也降低，细胞G0/G1期比例升高，细胞凋亡率升高，细胞中活化型Caspase-3、活化型Caspase-9蛋白水平升高，p21蛋白水平也升高，Cdk4蛋白水平降低，与感染阴性对照慢病毒载体和未经感染的细胞比较，差异有统计学意义（P<0.05）。结论:下调fascin可降低卵巢癌细胞增殖能力、抑制卵巢癌细胞从G0/G1期向S期转变并诱导卵巢癌细胞凋亡。     

miR-144-3p靶向zeb1调控卵巢癌细胞SKOV3的增殖和凋亡

目的:探讨miR-144-3p是否通过靶向E盒锌指结合蛋白1（zeb1）调控卵巢癌细胞SKOV3的增殖和凋亡。方法:qRT-PCR检测miR-144-3p在卵巢癌细胞和正常人卵巢上皮细胞中的表达差异。在卵巢癌细胞SKOV3中转染miR-144-3p mimics,MTT法测定细胞增殖,PI单染法检测细胞周期,Annexin V-FITC/PI双染法检测细胞凋亡,Western blot检测细胞中cyclinD1、p27、C-caspase-3蛋白表达。生物信息学软件预测miR-144-3p的靶基因可能为zeb1,荧光素酶报告系统鉴定其靶向关系。在卵巢癌细胞SKOV3中共转染miR-144-3p mimics、pcDNA3.1-zeb1,利用上述方法测定细胞增殖、周期和凋亡变化。结果:miR-144-3p在卵巢癌细胞中的表达水平低于正常人卵巢上皮细胞。转染miR-144-3p mimics后的卵巢癌细胞SKOV3增殖能力下降,细胞周期被阻滞在G1期,细胞凋亡增多,细胞中cyclinD1蛋白表达减少,p27、C-caspase-3蛋白表达增加。miR-144-3p靶向调控zeb1表达。pcDNA3.1-zeb1可以逆转miR-144-3p mimics对卵巢癌细胞增殖抑制、周期阻滞和凋亡促进作用。结论:miR-144-3p靶向zeb1抑制卵巢癌细胞SKOV3增殖并诱导细胞凋亡。     

Dulxanthone A induces cell cycle arrest and apoptosis via up-regulation of p53 through mitochondrial pathway in HepG2 cells

Natural products derived from plants provide a rich source for development of new anticancer drugs. Dulxanthone A was found to be an active cytotoxic component in Garcinia cowa by bioactivity-directed isolation. Studies to elucidate the cytotoxic mechanisms of dulxanthone A showed that dulxanthone A consistently induced S phase arrest and apoptosis in the most sensitive cell line HepG2. Furthermore, p53 was dramatically up-regulated, leading to altered expression of downstream proteins upon dulxanthone A treatment. Cell cycle related proteins, such as cyclin A, cyclin B, cyclin E, cdc-2, p21 and p27 were down-regulated. Some apoptosis correlated proteins were also altered following the drug treatment. Bcl-2 family members PUMA was up-regulated while Bcl-2 and Bax were down-regulated. However, the expression ratio of Bax/Bcl-2 was increased. This resulted in the release of cytochrome C from the mitochondria to the cytosol. Concurrently, Apaf-1 was stimulated with p53 by dulxanthone A. In result, cytochrome C, Apaf-1 and procaspase-9 form an apoptosome, which in turn triggered the activation of caspase-9, caspase-3 and downstream caspase substrates. Lamin A/C and PARP were down-regulated or cleaved, respectively. Moreover, cell cycle arrest and apoptosis in HepG2 cells induced by dulxanthone A were markedly inhibited by siRNA knockdown of p53. In summary, dulxanthone A is an active cytotoxic component of G. cowa. It induces cell cycle arrest at lower concentrations and triggers apoptosis at higher concentrations via up-regulation of p53 through the intrinsic mitochondrial pathway in HepG2 cells. Dulxanthone A is therefore likely a promising preventive and/or therapeutic agent against Hepatoma.     

小檗胺对胃癌细胞增殖、凋亡的影响及其分子机制

目的:探讨小檗胺对胃癌细胞（AGS和SGC-7901）增殖、凋亡的影响并探讨其分子机制。方法:利用MTT 实验检测胃癌细胞的增殖,利用集落形成实验检测胃癌细胞的生长, 流式细胞技术检测胃癌细胞的凋亡率以及细胞周期, Western blot检测凋亡相关蛋白的表达水平。结果:小檗胺（0~64 μg/ml）能够剂量依赖性以及时间依赖性的抑制 AGS和SGC-7901细胞的增殖 （P＜0.05）。集落形成实验结果显示小檗胺(32 μg/ml)能够抑制AGS和SGC-7901细胞的生长 （P＜0.05）。流式细胞实验显示,小檗胺(32 μg/ml)同时能够促进AGS和SGC-7901细胞的凋亡 （P＜0.05）,增殖G0/G1期细胞比例,降低S期细胞比例 （P＜0.05）。Western blot实验结果显示小檗胺(32 μg/ml)能够增加AGS和SGC-7901细胞的cleaved caspase-3,cleaved caspase-9以及Bax的蛋白水平,同时降低Bcl-2的蛋白水平 （P＜0.05）。结论:小檗胺能够抑制胃癌细胞的增殖,其机制可能与改变细胞周期以及促进细胞凋亡有关。     

AKAP12 induces apoptotic cell death in human fibrosarcoma cells by regulating CDKI-cyclin D1 and caspase-3 activity

AKAP12 (A-Kinase anchoring protein 12) is a protein kinase C substrate and a potential tumor suppressor. AKAP12 is down-regulated by several oncogenes and strongly suppressed in various cancers including prostate, ovarian and breast cancers. AKAP12 acts as a regulator of mitogenesis by anchoring key signal proteins such as PKA, PKC, and cyclins. In this study, AKAP12 was found to suppress tumor cell viability by inducing apoptosis via caspase-3 in HT1080 cells. This AKAP12-induced apoptosis was associated with a decreased expression of Bcl-2 and increased expression of Bax. Moreover, AKAP12-transfectant strongly induced the expression of Cip1/p21 and Kip1/p27, but resulted in a decrease in cyclin D1 involved in G(1) progression. Accordingly, these results suggest that AKAP12 may play an important role in tumor growth suppression by inducing apoptosis with the regulation of multiple molecules in the cell cycle progression.