Effects of Novel Diarylpentanoid Analogues of Curcumin on Secretory Phospholipase A2, Cyclooxygenases,Lipo‐oxygenase,and Microsomal Prostaglandin E Synthase‐1

Arachidonic acid and its metabolites have generated a heightened interest due to their significant role in inflammation. Inhibiting the enzymes involved in arachidonic acid metabolism has been considered as the synergistic anti‐inflammatory effect. A series of novel curcumin diarylpentanoid analogues were synthesized and evaluated for their inhibitory effects on activity of secretory phospholipase A₂, cyclooxygenases, soybean lipo‐oxygenase as well as microsomal prostaglandin E synthase‐1. Among the curcumin analogues, compounds 3 , 6 , 9 , 12, and 17 exhibited strong inhibition of secretory phospholipase A₂ activity, with IC₅₀ values ranging from 5.89 to 11.02 μm . Seven curcumin analogues 1 , 3 , 6 , 7 , 9 , 11, and 12 showed inhibition of cyclooxygenases‐2 with IC₅₀ values in the range of 46.11 to 94.86 μm , which were lower than that of curcumin. Compounds 3 , 6 , 7 , 12, and 17 showed strong inhibition of lipo‐oxygenase enzyme activity. Preliminary screening of diarylpentanoid curcumin analogues for microsomal prostaglandin E synthase‐1 activity revealed that four diarylpentanoid curcumin analogues 5 , 6 , 7 , and 13 demonstrated higher inhibition of microsomal prostaglandin E synthase‐1 activity with IC₅₀ ranging from 2.41 to 4.48 μm , which was less than that of curcumin. The present results suggest that some of these diarylpentanoid analogues were able to inhibit the activity of these enzymes. This raises the possibility that diarylpentanoid analogues of curcumin might serve as useful starting point for the design of improved anti‐inflammatory agents.     

冬凌草甲素对人乳腺癌细胞MCF-7增殖、细胞周期和凋亡的影响

目的 探讨冬凌草甲素(oridonin,Ori)对人乳腺癌细胞MCF-7的增殖、周期及凋亡的影响.方法 以不同浓度的Ori处理MCF-7细胞,MTT法检测细胞生长抑制率;应用流式细胞分析术检测细胞周期和凋亡.结果 20～50μM的Ori可显著抑制MCF-7细胞的增殖(P＜0.01),50 μM Ori作用24、36 h后细胞生长抑制率分别为67.37%和97.63%.50 μm Ori处理24 h后,MCF-7细胞的凋亡率为80.03%.结论 冬凌草甲素可显著抑制MCF-7细胞的生长,诱导细胞周期阻滞和细胞凋亡,是一种潜在的抗乳腺癌药物.     

CXCR4, inhibitors and mechanisms of action

In this review, the author discusses recent advances in anti-HIV inhibitors, targeting CXCR4, including natural and modified chemokines, peptides and organic compounds, their mechanisms of action, and the molecular process of virus invasion of immune cells. Peptides with strong anti-HIV activity exhibit several common features, such as electrostatic charges, cyclization, beta-turns and dimerization induced by a sulphide bond. Organic compounds, such as cyclams, display a unique metal-mediated mechanism in the binding process to its target CXCR4. Understanding of their mechanisms of action may be useful for the design of more effective drugs. Consecutive interactions of viral glycoprotein gp120 with CD4 and the co-receptor, CXCR4 or another co-receptor CCR5 on the cell surface leads to virus invasion into host cells. The molecular details of the binding between HIV glycoproteins and the co-receptors also provide a basis for anti-HIV therapy.     

Antiproliferative effects of quercetin through cell cycle arrest and apoptosis in human breast cancer MDA-MB-453 cells

To explore the anticancer effects of the flavonoid quercetin on human breast cancer MDA-MB-453 cells via cell cycle regulation and the induction of apoptosis, the antiproliferative effect of quercetin was first examined by MTT assay. When MDA-MB-453 cells were treated with quercetin for various periods of time (3–24 hrs) and at various doses (1–100 μM), cell growth decreased significantly in a time-and dose-dependent manner. To elucidate the mechanism underlying the antiproliferative effect of quercetin, cell cycle progression and the induction of apoptosis in MDA-MB-453 cells exposed to 100 μM quercetin for 24 hrs were investigated. Quercetin caused a remarkable increase in the number of sub-G1 phase cells, and an Annexin-V assay revealed that exposure to quercetin affected apoptosis. Moreover, treatment with quercetin increased Bax expression but decreased Bcl-2 expression. Cleaved caspase-3 and PARP expression was also increased by quercetin. Thus, quercetin has probable anticancer activity. Our results suggest the existence of multiple pathways for the induction of cell cycle arrest and apoptosis by quercetin.     

Coenzyme Q0 induces apoptosis and modulates the cell cycle in estrogen receptor negative breast cancer cells

We postulated that methoxy-substituted cyclic compounds could inhibit estrogen receptor (ER) negative breast cancer growth in vitro. Therefore, this study assessed the cytotoxic potential of various methoxy-substituted cyclic compounds [7,8-dimethoxyflavone, 4-methoxyphenylacetic acid, 2-methoxyphenylacetic acid, 4-methoxybenzophenone, 5-methoxy-1-indanone, and coenzyme Q0 (CoQ0)] toward ER-negative human breast cancer cells (MDA-MB-231 and SKBr3). Cytotoxicity was assessed using the sulforhodamine B assay. CoQ0 demonstrated the strongest cytotoxicity toward MDA-MB-231 and SKBr3 cells with IC50 values of 1.7 micromol/l and 3.1 micromol/l, respectively, whereas the other compounds were either much less potent or completely lacked cytotoxicity toward both breast cancer cell lines. Therefore, only CoQ0 was examined for its ability to modulate cell cycle progression and induce apoptosis. Cell cycle experiments, using propidium iodide staining and flow cytometry, demonstrated that CoQ0 at 7.5 micromol/l increased the proportion of MDA-MB-231 cells in G1/G0-phase by 16.6+/-0.6% of control (P<0.05), and increased in the proportion of S-phase SKBr3 cells by 37.8+/-5.8% over control (P<0.05). Induction of apoptosis was determined using propidium iodide/Annexin-V-FLUOS staining followed by flow cytometry. The results demonstrated that treatment with CoQ0 (7.5 micromol/l) increased the proportion of apoptotic MDA-MB-231 and SKBr3 cells by 12-fold and 4-fold over control (P<0.05), respectively. Thus, CoQ0 is a potent cytotoxic drug that induces apoptosis and modulates cell cycle progression in ER-negative breast cancer cells. Therefore, CoQ0 is an appropriate candidate for further study and development as a potential drug for ER-negative breast cancer.     

紫杉醇诱导人乳腺癌MCF-7细胞周期阻断及凋亡的基因表达谱分析

目的研究紫杉醇诱导人MCF-7细胞周期阻断及凋亡的分子机制。方法用流式细胞仪分析紫杉醇对MCF-7细胞周期变化的影响，用自制的含9 984个已知基因和EST的高密度基因芯片检测MCF-7细胞在不同浓度紫杉醇作用下的基因表达变化。结果MCF-7细胞在100 nmol·L^-1紫杉醇作用24 h，流式细胞仪结果显示77.8%细胞阻断在G₂/M期和1.3%细胞发生凋亡；基因表达谱分析发现：在12.5 nmol·L^-1 (IC₅₀)及100 nmol·L^-1紫杉醇作用下，分别有27及77个基因差异表达。结论紫杉醇可诱导MCF-7细胞周期阻断在G₂/M期并引起部分细胞凋亡，该作用与药物浓度有关。基因表达谱分析显示部分差异表达基因参与细胞微管及骨架结构、细胞周期调控、以及DNA损伤修复和凋亡过程。     

d-alpha-tocopheryl polyethylene glycol succinate (TPGS) induces cell cycle arrest and apoptosis selectively in Survivin-overexpressing breast cancer cells

d-alpha-tocopheryl polyethylene glycol succinate (TPGS) is a vitamin E derivative that has been intensively applied as a vehicle for drug delivery systems to enhance drug solubility and increase the oral bioavailability of anti-cancer drugs. Recently, it has been reported that TPGS acts as an anti-cancer agent alone or synergistically with chemotherapeutic drugs and increases the efficacy of nanoparticle formulations. In this study, we investigated the antitumor efficacy and the molecular mechanism of action of TPGS in breast cancer cell lines. Our results show that TPGS can induce G1/S cell cycle arrest and apoptosis in breast cancer cell lines (MCF-7 and MDA-MB-231) but not in “normal” (non-tumorigenic) immortalized cells (MCF-10A and MCF-12F). An investigation of the molecular mechanism of action of TPGS reveals that induction of G1/S phase cell cycle arrest is associated with upregulation of P21 and P27Kip1 proteins. Induction of apoptosis by TPGS involves the inhibition of phospho-AKT and the downregulation of the anti-apoptotic proteins Survivin and Bcl-2. Interestingly, our results also suggest that TPGS induces both caspase -dependent and -independent apoptotic signaling pathways and that this vitamin E derivative is selectively cytotoxic in breast cancer cell lines. When compared to the Survivin inhibitor YM155, TPGS was shown to be more selective for cancer cell growth inhibition. Overall our results suggest that TPGS may not only be useful as a carrier molecule for drug delivery, but may also exert intrinsic therapeutic effects suggesting that it may promote a synergistic interaction with formulated chemotherapeutic drugs.     

Effects of estradiol, PCB3, and their hydroxylated metabolites on proliferation, cell cycle, and apoptosis of human breast cancer cells

Certain estradiol metabolites and industrial pollutants, like polychlorinated biphenyls, may play a more important role in enhancing breast cancer risk than 17β-estradiol. The aim of this study was to compare the effects of 17β-estradiol (E2) with that of the air pollutant 4-chlorobiphenyl (PCB3) and four of their hydroxylated metabolites on cell cycle, proliferation, and apoptosis in MCF-7 human breast cancer cells at concentrations of 0.1-10nM (E2, 2-OH-E2, and 4-OH-E2) and 0.3-300nM (PCB3, 4-OH-PCB3, and 3, 4-diOH-PCB3) and 24-260h of exposure. E2 increased cell proliferation and cells in S-phase at all time points. 2-OH-E2 and 4-OH-E2 had no effect on the cell cycle, but a stimulatory action on cell proliferation from 72 to 260h of exposure to 4-OH-E2 and at 260h to 2-OH-E2 was seen. E2 and its metabolites had no effect on apoptosis. PCB3 and 4-OH-PCB3 showed no effect on proliferation, apoptosis or cell cycle distribution at any concentration and time point. Longer time exposures to 3,4-di-OH-PCB at 300nM caused a decrease of cells and an increase in G2/M and apoptotic cells. These results confirm the proliferative effect of E2 and its metabolite 4-OH-E2 in estrogen receptor positive breast cancer cells, but show no mitogenic activity for PCB3 and 4-OH-PCB3. However, the cell cycle and apoptosis effects of 3,4-diOH-PCB3 need further analysis.     

蜂斗菜素对宫颈癌细胞增殖、细胞周期和凋亡的影响

目的 研究蜂斗菜素对宫颈癌细胞增殖、细胞周期和凋亡的影响及潜在机制.方法 以蜂斗菜素0μmol/L为对照,用5、15、45μmol/L的蜂斗菜素处理宫颈癌SiHa细胞,四甲基偶氮唑盐比色法(MTT)检测细胞在24、48和72 h的增殖活性,蛋白质印迹法(Western blotting)检测SiHa细胞中细胞周期蛋白D...     

The anti-proliferative inhibition of ellipticine in human breast mda-mb-231 cancer cells is through cell cycle arrest and apoptosis induction

Ellipticine, a cytotoxic plant alkaloid, is known to inhibit topoisomerase II. Here we report the mechanism of apoptosis induction and cell cycle arrest by ellipticine in human breast MDA-MB-231 cancer cells. Ellipticine treatment arrested MDA-MB-231 cells at the G2/M phase after 6 h of treatment. This effect was strongly associated with a concomitant decrease in the level of cyclin B1, Cdc25 and Cdc2, and increase in phospho-Cdc2 (Tyr15). In addition, ellipticine also induced apoptosis in MDA-MB-231 cells, as determined by using both DNA fragmentation and Annexin-V staining assay. Ellipticine increased the expression of Bax, but decreased the level of Bcl-2, Bcl-XL and X-linked inhibitor of apoptosis protein (XIAP), and subsequently triggered the mitochondrial apoptotic pathway (release of cytochrome c, and activation of caspase-9 and -3). In addition, pre-treatment of cells with caspase-9 inhibitor inhibited ellipticine-induced cell proliferation and apoptosis, indicating that caspase-9 activation was involved in MDA-MB-231 cell apoptosis induced by ellipticine. Taken together, our study suggests that the inhibition of cell cycle progression signaling and initiation of the mitochondrial apoptotic system may participate in the anti-proliferative activity of ellipticine in MDA-MB-231 cells.     

奥曲肽对人肝癌细胞Huh-7增殖、细胞周期和凋亡的影响

目的探讨奥曲肽对人肝癌细胞Huh-7增殖、细胞周期及凋亡的影响。方法 Huh-7细胞用不同浓度奥曲肽(0、10-9、10-8、10-7、10-6、10-5 mol/L,分别为A、B、C、D、E、F组)处理,MTT法检测细胞生长抑制率,流式细胞术检测细胞周期和凋亡,Western blot法检测半胱天冬氨酸蛋白酶3(Caspase-3)表达。结果与A组相比,其余各组Huh-7细胞的生长抑制率、G1期细胞的比例、凋亡率及Caspase-3蛋白表达均以浓度依赖性的方式明显增加。结论奥曲肽可显著抑制Huh-7细胞的生长,诱导细胞周期阻滞和细胞凋亡;且奥曲肽可能通过启动Caspases途径诱导人肝癌细胞Huh-7凋亡。     

蛇葡萄素对人宫颈癌SiHa细胞增殖、周期及凋亡的影响

目的探究蛇葡萄素(ampelopsin,AMP)对人宫颈癌SiHa细胞增殖、周期、凋亡的影响及其可能的作用机制。方法MTT法检测不同浓度(10、20、40、80、160、320μmol·L^-1)和不同干预时间(24、48、72 h)的AMP对SiHa细胞增殖抑制作用;Hoechst 33258法、Annexin-FITC/PI法检测AMP对SiHa细胞凋亡的影响;流式细胞术检测细胞周期变化;Rh-123法检测线粒体膜电位的变化;Western blot检测AMP对SiHa细胞中Bcl-2、Bax、Cleaved-caspase-3蛋白表达的影响。结果AMP对SiHa细胞抑制率呈浓度和时间依赖性(P<0.05),最低IC 50值为40.33μmol·L^-1;随着AMP浓度的增加或作用时间的延长,细胞凋亡率逐渐增加(P<0.05);当AMP浓度为80μmol·L^-1时,细胞周期阻滞在G 2/M期,呈一定的时间依赖性;线粒体膜电位随AMP浓度上升而下降;Bax/Bcl-2和Cleaved-caspase-3表达水平均上调,呈浓度和时间依赖性(P<0.05)。结论AMP明显抑制SiHa细胞的增殖,阻滞细胞周期于G 2/M期,可能通过线粒体途径诱导SiHa细胞凋亡。     

Tetrahydrocurcumin induces G2/M cell cycle arrest and apoptosis involving p38 MAPK activation in human breast cancer cells

Curcumin (CUR) is a major naturally-occurring polyphenol of Curcuma species, which is commonly used as a yellow coloring and flavoring agent in foods. In recent years, it has been reported that CUR exhibits significant anti-tumor activity in vivo. However, the pharmacokinetic features of CUR have indicated poor oral bioavailability, which may be related to its extensive metabolism. The CUR metabolites might be responsible for the antitumor pharmacological effects in vivo. Tetrahydrocurcumin (THC) is one of the major metabolites of CUR. In the present study, we examined the efficacy and associated mechanism of action of THC in human breast cancer MCF-7 cells for the first time. Here, THC exhibited significant cell growth inhibition by inducing MCF-7 cells to undergo mitochondrial apoptosis and G2/M arrest. Moreover, co-treatment of MCF-7 cells with THC and p38 MAPK inhibitor, SB203580, effectively reversed the dissipation in mitochondrial membrane potential (Δψm), and blocked THC-mediated Bax up-regulation, Bcl-2 down-regulation, caspase-3 activation as well as p21 up-regulation, suggesting p38 MAPK might mediate THC-induced apoptosis and G2/M arrest. Taken together, these results indicate THC might be an active antitumor form of CUR in vivo, and it might be selected as a potentially effective agent for treatment of human breast cancer.     

The natural antioxidant alpha-lipoic acid induces p27-dependent cell cycle arrest and apoptosis in MCF-7 human breast cancer cells

Unlike normal cells, tumor cells survive in a specific redox environment where the elevated reactive oxygen species contribute to enhance cell proliferation and to suppress apoptosis. Alpha-lipoic acid, a naturally occurring reactive oxygen species scavenger, has been shown to possess anticancer activity, due to its ability to suppress proliferation and to induce apoptosis in different cancer cell lines. Since at the moment little information is available regarding the potential effects of alpha-lipoic acid on breast cancer, in the present study we addressed the question whether alpha-lipoic acid induces cell cycle arrest and apoptosis in the human breast cancer cell line MCF-7. Moreover, we investigated some molecular mechanisms which mediate alpha-lipoic acid actions, focusing on the role of the PI3-K/Akt signalling pathway. We observed that alpha-lipoic acid is able to scavenge reactive oxygen species in MCF-7 cells and that the reduction of reactive oxygen species is followed by cell growth arrest in the G1 phase of the cell cycle, via the specific inhibition of Akt pathway and the up-regulation of the cyclin-dependent kinase inhibitor p27^kip1, and by apoptosis, via changes of the ratio of the apoptotic-related protein Bax/Bcl-2. Thus, the anti-tumor activity of alpha-lipoic acid observed in MCF-7 cells further stresses the role of redox state in regulating cancer initiation and progression.     

Geraniol and beta-ionone inhibit proliferation, cell cycle progression, and cyclin-dependent kinase 2 activity in MCF-7 breast cancer cells independent of effects on HMG-CoA reductase activity

3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase catalyzes the formation of mevalonate, a precursor of cholesterol that is also required for cell proliferation. Mevalonate depletion results in a G1 phase cell cycle arrest that is mediated in part by impaired activity of cyclin-dependent kinase (CDK) 2, and decreased expression of positive regulators of G1 to S phase progression. Inhibition of mevalonate synthesis may, therefore, be a useful strategy to impair the growth of malignant cells. Plant isoprenoids, including beta-ionone and geraniol, have previously been shown to inhibit rodent mammary tumor development, and rodent and avian hepatic HMG-CoA reductase activity. We hypothesized that the putative anti-proliferative and cell cycle inhibitory effects of beta-ionone and geraniol on MCF-7 human breast cancer cells in culture are mediated by mevalonate depletion resulting from inhibition of HMG-CoA reductase activity. Flow cytometric analysis showed a G1 arrest in isoprenoid-treated MCF-7 cells, and also a G2/M arrest at higher concentrations of isoprenoids. These compounds minimally affected the growth of MCF-10F normal breast epithelial cells. Both beta-ionone and geraniol inhibited CDK 2 activity and dose-dependently decreased the expression of cyclins D1, E, and A, and CDK 2 and 4, without changing the expression of p21cip1 or p27kip1. Although both beta-ionone and geraniol also inhibited MCF-7 proliferation, only geraniol inhibited HMG-CoA reductase activity. While these effects were significantly correlated (r2=0.89, P <0.01), they were not causally related, since exogenous mevalonate did not restore growth in geraniol-inhibited cells. These findings indicate that mechanisms other than impaired mevalonate synthesis mediate the anti-proliferative and cell cycle regulatory effects of beta-ionone and geraniol in human breast cancer cells.