Effects of Rapamycin on Cell Apoptosis in MCF-7 Human Breast Cancer Cells

Background: Rapamycin is an effective anti-angiogenic drug. However, the mode of its action remainsunclear. Therefore, in this study, we aimed to elucidate the antitumor mechanism of rapamycin, hypotheticallyvia apoptotic promotion, using MCF-7 breast cancer cells. Materials and Methods: MCF-7 cells were platedat a density of 15105 cells/well in 6-well plates. After 24h, cells were treated with a series of concentrations ofrapamycin while only adding DMEM medium with PEG for the control regiment and grown at 37oC, 5% CO2and 95% air for 72h. Trypan blue was used to determine the cell viability and proliferation. Untreated andrapamycin-treated MCF-7 cells were also examined for morphological changes with an inverted-phase contrastmicroscope. Alteration in cell morphology was ascertained, along with a stage in the cell cycle and proliferation.In addition, cytotoxicity testing was performed using normal mouse breast mammary pads. Results: Our resultsclearly showed that rapamycin exhibited inhibitory activity on MCF-7 cell lines. The IC50 value of rapamycin onthe MCF-7 cells was determined as 0.4μg/ml (p<0.05). Direct observation by inverted microscopy demonstratedthat the MCF-7 cells treated with rapamycin showed characteristic features of apoptosis including cell shrinkage,vascularization and autophagy. Cells underwent early apoptosis up to 24% after 72h. Analysis of the cell cycleshowed an increase in the G0G1 phase cell population and a corresponding decrease in the S and G2M phasepopulations, from 81.5% to 91.3% and 17.3% to 7.9%, respectively. Conclusions: This study demonstrated thatrapamycin may potentially act as an anti-cancer agent via the inhibition of growth with some morphologicalchanges of the MCF-7 cancer cells, arrest cell cycle progression at G0/G1 phase and induction of apoptosis inlate stage of apoptosis. Further studies are needed to further characterize the mode of action of rapamycin asan anti-cancer agent.     

Exopolysaccharide from Marine Bacillus velezensis MHM3 Induces Apoptosis of Human Breast Cancer MCF-7 Cells through a Mitochondrial Pathway

Objective: The production of new natural pharmaceutical agents that increase the efficiency of chemotherapywithout affecting the normal cells is the goal of all researchers. Therefore, the present study expects to evaluatethe antioxidant and anticancer studies against MCF-7 cell lines of EPS produced by novel Egyptian marine bacterialstrain. Methods: Marine bacterium was isolated, purified and identified by 16S rRNA gene amplification and sequenceanalyses. MHMEPS (the produced EPS) was analyzed by Fourier Transform Infra-red (FTIR), monosugars identificationby HPLC, molecular weight estimation and sulfur content were determined. While, in-vitro antioxidants characterswas determined using various methods and anticancer studies against MCF-7 cell lines. Results: Bacillus velezensisMHM3 produced 5.8 g/L of MHMEPS. The chemical analysis of MHMEPS showed 24% uronic acid and 18.19%sulfate and monosugars glucuronic acid, glucose, fructose and rhamnose with molar ratio of 4.00: 2.00: 1.00: 0.13,correspondingly, with an overall weight average molecular weight Mw of 1.145×104 g/mol and the number average ofmolecular weights Mn of 5.155 ×103 g/mol. The FTIR analysis and periodate oxidation indicate the existence ofα-(1–4) linkage acidic polysaccharide. MHMEPS showed antioxidant scavenging activity against DPPH•, H2O2 andMetal chelating activity, respectively. So, reducing power method give high activity at 500 μg/ml. MHMEPS hinderthe proliferation of MCF-7 cells at 5-80 μg/ml compared to the control group. Moreover, induced apoptosis wasassociated with activation of caspase-3. Also increased cytochrome C levels significantly in a dose-dependent mannercompared with the control. The Caspase-3 activity was raised in MHMEPS treated MCF-7 cells compared withthe control (p<0.05) in a dose-dependent manner. Therefore, the result of DNA fragmentation was confirmed by DNAladder assay. We presume that MHMEPS has high potential at its low concentration, as a novel restorative agent forthe treatment of MCF-7 cells, with no cytotoxicity against normal cells.     

Wnt信号通路在姜黄素诱导乳腺癌MCF-7细胞凋亡中作用机制

目的 探讨Wnt通路在姜黄素诱导人乳腺癌MCF-7细胞凋亡中的作用机制.方法 将MCF-7细胞培养液随机分为5组,分别加入15、30、60、120μmol/L的姜黄素,对照组不加,培养12,24,48 h后采用CCK-8法检测细胞增殖能力.分A、B两组(剂量组、时间组)采用Annexin V-FITC/PI双染流式细胞术(FCM)观测细胞凋亡及细胞周期分布;Western Blotting法检测A、B两组的Wnt通路相关蛋白,并进行相应的相关性分析探讨Wnt通路与乳腺癌MCF-7细胞凋亡的关系.结果 CCK-8结果显示,随培养时间延长,姜黄素各浓度组MCF-7细胞增殖抑制率逐渐增高(均P<0.05);在同一时间点,随着姜黄素浓度升高,细胞增殖抑制率逐渐增高(均P<0.05).FCM染色结果显示,随着姜黄素浓度增加、作用时间延长MCF-7细胞凋亡指数逐渐上升(均P<0.05),且G1/S期细胞增加越多(P<0.05).Western Blotting实验结果显示MCF-7细胞中Wnt1、β-catenin的表达下调程度呈现剂量时间依赖性(P<0.05).相关性分析显示细胞抑制率、G0/G1期细胞百分比、细胞凋亡率均与Wnt通路相关蛋白Wnt1、β-catenin的表达呈现较明显的相关性(P<0.05).结论 姜黄素的抗癌活性与抗增殖能力具有明显的剂量时间依赖性,且Wnt通路在姜黄素诱导乳腺癌MCF-7细胞抑制、凋亡过程中发挥了重要作用.     

Momordica cochinchinensis Aril Extract Induced Apoptosis in Human MCF-7 Breast Cancer Cells

Momordica cochinchinensis Spreng (MC) has been used in traditional medicine due to its high carotenoidcontent. The objective of this study was to investigate mechanisms underlying apoptotic effects of MC on humanMCF-7 breast cancer cells. A lycopene-enriched aril extract of MC (AE) showed cytotoxicity and antiestrogenicityto MCF-7 cells. On DAPI staining, AE induced cell shrinkage and chromatin condensation were evident. Withflow cytometric analysis, AE increased the percentage of cells in an early apoptosis stage when compared withthe control group. RT-PCR analysis showed AE to significantly increase the expression of the proapoptotic baxgene without effect on expression of the anti-apoptotic bcl-2 gene. Moreover, AE enhanced caspase 6, 8 and 9activity. Taken together, we conclude that AE of MC fruit has anticancer effects on human MCF-7 breast cancercells by induction of cell apoptosis via both intrinsic and extrinsic pathways of signaling     

Glehnia littoralis Root Extract Induces G0/G1 Phase Cell Cycle Arrest in the MCF-7 Human Breast Cancer Cell Line

Glehnia littoralis (GL) is widely used as an oriental medicine for cough, fever, stroke and other disease conditions. However, the anti-cancer properties of GL on MCF-7 human breast cancer cells have not been investigated. In order to elucidate anti-cancer properties and underlying cell death mechanisms, MCF-7cells (5 X 104/well) were treated with Glehnia littoralis root extract at 0-400 ug/ml. A hot water extract of GL root inhibited the proliferation of MCF-7 cells in a dose-dependent manner. Analysis of the cell cycle after treatment of MCF-7 cells with increasing concentrations of GL root extract for 24 hours showed significant cell cycle arrest in the G1 phase. RT-PCR and Western blot analysis both revealed that GL root extract significantly increased the expression of p21 and p27 with an accompanyingdecrease in both CDK4 and cyclin D1. Our reuslts indicated that GL root extract arrested the proliferation of MCF-7 cells in G1 phase through inhibition of CDK4 and cyclin D1 via increased induction of p21 and p27. In summary, the current study showed that GL could serve as a potential source of chemotherapeutic or chemopreventative agents against human breast cancer.     

Silibinin Enhances Ultraviolet B-Induced Apoptosis in MCF-7 Human Breast Cancer Cells

Purpose

Chemotherapies for breast cancer generally have strong cellular cytotoxicity and severe side effects. Thus, significant emphasis has been placed on combinations of naturally occurring chemopreventive agents. Silibinin is a major bioactive flavonolignan extracted from milk thistle with chemopreventive activity in various organs including the skin, prostate, and breast. However, the mechanism underlying the inhibitory action of silibinin in breast cancer has not been completely elucidated. Therefore, we investigated the effect of silibinin in MCF-7 human breast cancer cells and determined whether silibinin enhances ultraviolet (UV) B-induced apoptosis.

Methods

The effects of silibinin on MCF-7 cell viability were determined using the MTT assay. The effect of silibinin on PARP cleavage, as the hallmark of apoptotic cell death, and p53 protein expression in MCF-7 cells was analyzed using Western blot. The effect of silibinin on UVB-induced apoptosis in MCF-7 cells was analyzed by flow cytometry.

Results

A dose- and time-dependent reduction in viability was observed in MCF-7 cells treated with silibinin. Silibinin strongly induced apoptotic cell death in MCF-7 cells, and induction of apoptosis was associated with increased p53 expression. Moreover, silibinin enhanced UVB-induced apoptosis in MCF-7 cells.

Conclusion

Silibinin induced a loss of cell viability and apoptotic cell death in MCF-7 cells. Furthermore, the combination of silibinin and UVB resulted in an additive effect on apoptosis in MCF-7 cells. These results suggest that silibinin might be an important supplemental agent for treating patients with breast cancer.     

Inactivated Sendai Virus Strain Tianjin Induces Apoptosis in Human Breast Cancer MDA-MB-231 Cells

Sendai virus strain Tianjin is a novel genotype. Here, we investigate the antitumor and proapoptotic effects of ultraviolet-inactivated Sendai virus strain Tianjin (UV-Tianjin) on human breast cancer MDA-MB-231 cells in vitro, as well as the involvement of the apoptotic pathway in the mechanism of UV-Tianjin-induced antitumor effects. MTT assays showed that treatment with UV-Tianjin dose-dependently inhibited the proliferation of MDAMB-231 cells but not normal MCF 10A breast epithelium cells. Hoechst staining and flow cytometric analysis revealed that UV-Tianjin induced apoptosis of MDA-MB-231 cells in a dose-dependent manner. Moreover, UV-Tianjin treatment resulted in reduction in the mitochondria membrane potential (MMP) and release of cytochrome complex (cyt c) via regulation of Bax and Bcl-2, as well as activation of caspase-9, caspase-3, Fas, FasL and caspase-8 in MDA-MB-231 cells. In summary, our study suggests that UV-Tianjin exhibits anticancer activity in human breast cancer MDA-MB-231 cells through inducing apoptosis, which may involve both the endogenous mitochondrial and exogenous death receptor pathways.     

Hsp90 Inhibitor; NVP-AUY922 in Combination with Doxorubicin Induces Apoptosis and Downregulates VEGF in MCF-7 Breast Cancer Cell Line

Objective: Breast cancer is one of the most prevalent malignancies and leading causes of females’ mortality worldwide. Because of resistance to various treatment options, new treatments based on molecular targeting has introduced as noticeable strategies in cancer treatment. In this regard, heat shock protein 90 (Hsp90) inhibitors are proposed as effective anticancer drugs. The goal of the study was to utilize a combination of the doxorubicin (DOX) and NVP-AUY 922 on the MCF-7 breast cancer model to investigate the possible cytotoxic mechanisms. Methods: MCF-7 breast cancer cell line was prepared and treated with various concentrations of DOX and NVP-AUY922 in single-drug treatments. We investigated the growth-inhibitory pattern by MTT assay after continuous exposure to NVP-AUY922 and DOX in order to determine dose-response. Then the combinatorial effects were evaluated in concentrations of 0.5 × IC50, 0.2 × IC50, 1 × IC50 and, 2 × IC50 of each drugs. Based on MTT results of double combinations, low effective doses were selected for Real-time PCR [caspase3 and vascular endothelial growth factor(VEGF)] and caspase 3 enzyme activity. Results: A dose-dependent inhibitory effects were presented with increasing the doses of both drugs in single treatments. The upregulation of caspase 3 and downregulation of VEGF mRNA were observed in double combinations of NVP-AUY922 and DOX versus single treatments. Also, in these combinations in low doses of examined drugs (0.5 × IC50, 0.2 × IC50), higher caspase 3 activity were presented in comparison to single treatments (p<0.05). Conclusions: Our findings indicate an effective action of NVP-AUY922 in combined with DOX in this cell line. These results can predict the treatment outcome in this model.     

Neem Seed Oil Induces Apoptosis in MCF-7 and MDA MB-231Human Breast Cancer Cells

Background: In traditional Indian medicine, azadirachta indica (neem) is known for its wide range of medicinal properties. Various parts of neem tree including its fruit, seed, bark, leaves, and root have been shown to possess antiseptic, antiviral, antipyretic, anti-inflammatory, antiulcer, antimalarial, antifungal and anticancer activity. Materials and Methods: MCF-7 and MDA MB-231 cells were exposed to various concentrations of 2% ethanolic solution of NSO (1-30 μl/ml) and further processed for cell viability, cell cycle and apoptosis analysis. In addition, cells were analyzed for alteration in Mitochondrial Membrane Potential (MMP) and generation of Reactive Oxygen Species (ROS) using JC-1 and DCFDA staining respectively. Results: NSO give 50% inhibition at 10 μl/ml and 20 μl/ml concentration in MCF-7 and MDA MB-231 cells respectively and, arrests cells at G0/G1 phase in both the cell types. There was a significant alteration in mitochondrial membrane potential that leads to the generation of ROS and induction of apoptosis in NSO treated MCF-7 and MDA MB-231 cells. Conclusion: The results showed that NSO inhibits the growth of human breast cancer cells via induction of apoptosis and G1 phase arrest. Collectively these results suggest that NSO could potentially be used in the management of breast cancer.     

Oxidants-Antioxidants Profile in the Breast Cancer Cell Line MCF-7

Reactive oxygen species (ROS) have various biological effects and they are non-linear in characteristic. In high oxidativestress, they may cause cytotoxicity, inhibit cell proliferation, and induce cell death in the form of apoptosis/necrosis;while in low or medium oxidative stress, ROS may cause DNA damage, cell mutation, inflammation, cell proliferation,and eventually they may induce carcinogenesis. Antioxidants are compounds with the ability to reduce ROS. Cell lineMCF-7 is one of the breast cancer cell lines that is known to have small amount of antioxidant MnSOD compared to theother cell lines. Low antioxidant MnSOD level in breast cancer cell line MCF-7 leads to low concentration of hydrogenperoxide, because antioxidant MnSOD will convert radical superoxide to hydrogen peroxide. The aim of this researchwas to analyze oxidants and antioxidants profile in breast cancer cell line MCF-7 and their relationship with cell number.Observations were conducted for 5 days. The cell number was counted with tryphan blue method and haematometer.The concentration of radical superoxide was measured with DHE staining using LSCM tipe Olympus Fluoview FV1000-Ver 1.7. MnSOD activity, hydrogen peroxide concentration, and catalase activity were measured with ELISA.The results showed that the longer of observation, the greater concentration of oxidants and MnSOD activity, but therewas no change in catalase activity. Conclusion the increase in cancer cells number is influenced by radical superoxide.     

Antioxidant and Apoptotic Effects of an Aqueous Extract of Urtica dioica on the MCF-7 Human Breast Cancer Cell Line

Breast cancer is the most prevalent cancer and one of the leading causes of death among women in the world.Plants and herbs may play an important role in complementary or alternative treatment. The aim of this studywas to evaluate the antioxidant and anti-proliferative potential of Urtica dioica. The anti oxidant activity of anaqueous extract of Urtica dioica leaf was measured by MTT assay and the FRAP method while its anti-proliferativeactivity on the human breast cancer cell line (MCF-7) and fibroblasts isolated from foreskin tissue was evaluatedusing MTT assay. Mechanisms leading to apoptosis were also investigated at the molecular level by measuringthe amount of anti and pro-apoptotic proteins and at the cellular level by studying DNA fragmentation andannexin V staining by flow cytometry. The aqueous extract of Urtica dioica showed antioxidant effects with acorrelation coefficient of r2=0.997. Dose-dependent and anti-proliferative effects of the extract were observedonly on MCF-7 cells after 72 hrs with an IC50 value of 2 mg/ml. This anti proliferative activity was associatedwith an increase of apoptosis as demonstrated by DNA fragmentation, the appearance of apoptotic cells inflow cytometry analysis and an increase of the amount of calpain 1, calpastatin, caspase 3, caspase 9, Bax andBcl-2, all proteins involved in the apoptotic pathway. This is the first time such in vitro antiproliferative effectof aqueous extract of Urtica dioica leaf has been described for a breast cancer cell line. Our findings warrantfurther research on Urtica dioica as a potential chemotherapeutic agent for breast cancer.     

Myricetin Exerts its Apoptotic Effects on MCF-7 Breast Cancer Cells through Evoking the BRCA1-GADD45 Pathway

Objective: Myricetin is a polyphenol flavonoid with nutraceutical values which is abundantly found as the main ingredient of various foods and beverages. It has been reported that the function of myricetin is to trigger apoptosis in several types of cancers. The present study intended to investigate the apoptotic effects of myricetin on MCF-7 breast cancer cells and to assess its possible mechanisms of action. Materials and Methods: MCF-7 breast cancer cells were assigned to four groups: Control (cells in normal condition); myricetin (cells treated with the IC50 dosage of myricetin) in three different incubation times (24, 48, and 72 h). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, annexin V assay, flow cytometry, real-time polymerase chain reaction (PCR), and caspase-3 assay were used to estimate the apoptosis function of myricetin in breast cancer. Results: The expression levels of apoptosis-related genes caspase-3, caspase-8, caspase-9, and the BAX /Bcl-2 ratio as well as the expression of p53, BRCA1, GADD45 genes were significantly increased following the treatment of MCF-7 breast cancer cells with myricetin. The annexin V assay demonstrated the significant expression of annexin which was also detected by flow cytometry. Conclusion: Myricetin efficiently induces apoptosis in MCF-7 breast cancer cells by evoking both extrinsic and intrinsic apoptotic pathways. Myricetin may exert its apoptotic effects on MCF-7 cells by inducing the BRCA1- GADD45 pathway.     

Effect of Sesamin on Apoptosis and Cell Cycle Arrest in Human Breast Cancer MCF-7 Cells

Dietary prevention has been known to reduce breast cancer risk. Sesamin is one of the major components insesame seeds and has been widely studied and proven to have anti-proliferation and anti-angiogenic effects oncancer cells. In this study, the influence of sesamin was tested in the human breast cancer MCF-7 cell line forcell viability (MTT assay) and cell cycling (flow cytometry). Results showed that sesamin dose-dependently (1,10 and 50 μM) reduced the cell viability and increased LDH release and apoptosis (TUNEL assay). In addition,there was a significant increase of sub-G1 phase arrest in the cell cycle after sesamin treatment. Furthermore,sesamin increased the expression of apoptotic markers of Bax, caspase-3, and cell cycle control proteins, p53 andcheckpoint kinase 2. Taken together, these results suggested that sesamin might be used as a dietary supplementf or prevention of breast cancer by modulating apoptotic signal pathways and inhibiting tumor cell growth.     

Beta-asarone Induces LoVo Colon Cancer Cell Apoptosis by Up-regulation of Caspases through a Mitochondrial Pathway in vitro and in vivo

Beta-asarone is one of the main bioactive constituents in traditional Chinese medicine Acorus calamu. Previousstudies have shown that it has antifungal and anthelmintic activities. However, little is known about its anticancereffects. This study aimed to determine inhibitory effects on LoVo colon cancer cell proliferation and to clarifythe underlying mechanisms in vitro and in vivo. Dose-response and time-course anti-proliferation effects wereexamined by MTT assay. Our results demonstrated that LoVo cell viability showed dose- and time-dependence onβ-asarone. We further assessed anti-proliferation effects as β-asarone-induced apoptosis by annexin V-fluoresceinisothiocyanate/propidium iodide assay usinga flow cytometer and observed characteristic nuclear fragmentationand chromatin condensation of apoptosis by microscopy. Moreover, we found the apoptosis to be induced throughthe mitochondrial/caspase pathway by decreasing mitochondrial membrane potential (MMP) and reducing theBcl-2-to-Bax ratio, in addition to activating the caspase-9 and caspase-3 cascades. Additionally, the apoptosiscould be inhibited by a pan-caspase inhibitor, carbobenzoxy-valyl-alanyl-aspartyl-[O-methyl]-fluoromethylketone(Z-VAD-FMK). When nude mice bearing LoVo tumor xenografts were treated with β-asarone, tumor volumeswere reduced and terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) assays ofexcised tissue also demonstrated apoptotic changes. Taken together, these findings for the first time provideevidence that β-asarone can suppress the growth of colon cancer and the induced apoptosis is possibly mediatedthrough mitochondria/caspase pathways.     

白藜芦醇抑制MCF-7乳腺癌细胞增殖的机制研究

研究白藜芦醇对MCF-7乳腺癌细胞抑制效应及其作用机制。方法：以人MCF-7乳腺癌细胞株为研究对象,利用MTT方法研究白藜芦醇抑制MCF-7乳腺癌细胞的生物学效应;观察在ERK1/2抑制剂PD98059预处理情况下,白藜芦醇抑制MCF-7乳腺癌细胞增殖效应的改变;利用免疫印迹方法观察白藜芦醇对MCF-7乳腺癌细胞中ERK1/2与AKT信号分子的蛋白表达。结果：白藜芦醇能够明显降低MCF-7乳腺癌细胞增殖能力,该作用呈一定的浓度依赖性关系。在ERK1/2抑制剂PD98059预处理情况下,白藜芦醇对MCF-7乳腺癌细胞增殖抑制效应能明显抑制,PD98059可明显减轻该效应。同时,白藜芦醇明显增加p-ERK1/2蛋白表达,降低p-AKT表达水平,但对ERK1/2与AKT蛋白表达无改变。结论：白藜芦醇能够有效抑制MCF-7乳腺癌细胞增殖,该效应与白藜芦醇对ERK1/2及AKT信号途径的调节有关。     

别直参抑制人乳腺癌细胞MCF-7体外增殖

[目的]评价别直参对MCF-7细胞体外增殖的影响,并检测其对凋亡相关蛋白bax/bcl-2表达的影响.[方法]采用MTT比色法检测对MCF-7细胞增殖的作用;流式细胞术检测对MCF-7细胞凋亡的影响;免疫组化法检测bax/bcl-2的表达.[结果]别直参高剂量组作用MCF-7细胞24h后,MTT检测增殖率为89.83％,提示有抑制MCF-7细胞体外增殖的作用(P＜0.05);流式细胞术检测高剂量组细胞凋亡率明显升高(P＜0.05);免疫组化法检测高剂量组能上调MCF-7细胞bax的表达,并下调bcl-2的表达.[结论]别直参高剂量组具有一定的诱导MCF-7细胞凋亡效应作用,其机制可能通过上调bax的表达和下调bcl-2的表达.     

Taxol Produced from Endophytic Fungi Induces Apoptosis in Human Breast,Cervical and Ovarian Cancer Cells

Currently, taxol is mainly extracted from the bark of yews; however, this method can not meet its increasingdemand on the market because yews grow very slowly and are a rare and endangered species belonging to firstlevelconservation plants. Recently, increasing efforts have been made to develop alternative means of taxolproduction; microbe fermentation would be a very promising method to increase the production scale of taxol.To determine the activities of the taxol extracted from endophytic fungus N. sylviforme HDFS4-26 in inhibitingthe growth and causing the apoptosis of cancer cells, on comparison with the taxol extracted from the bark ofyew, we used cellular morphology, cell counting kit (CCK-8) assay, staining (HO33258/PI and Giemsa), DNAagarose gel electrophoresis and flow cytometry (FCM) analyses to determine the apoptosis status of breastcancer MCF-7 cells, cervical cancer HeLa cells and ovarian cancer HO8910 cells. Our results showed that thefungal taxol inhibited the growth of MCF-7, HeLa and HO8910 cells in a dose-and time-dependent manner.IC50 values of fungal taxol for HeLa, MCF-7 and HO8910 cells were 0.1-1.0 μg/ml, 0.001-0.01 μg/ml and 0.01-0.1 μg/ml, respectively. The fungal taxol induced these tumor cells to undergo apoptosis with typical apoptoticcharacteristics, including morphological changes for chromatin condensation, chromatin crescent formation,nucleus fragmentation, apoptotic body formation and G2/M cell cycle arrest. The fungal taxol at the 0.01-1.0 μg/ml had significant effects of inducing apoptosis between 24-48 h, which was the same as that of taxol extractedfrom yews. This study offers important information and a new resource for the production of an importantanticancer drug by endofungus fermentation.     

4-氨基吡啶与多西紫杉醇抗人乳腺癌细胞MCF-7 作用及相互关系探讨*

目的:通过研究钾离子通道阻断剂4- 氨基吡啶（4-AP ）对肿瘤化疗药物多西紫杉醇（docetaxel ,DOC ）的抗人乳腺癌细胞MCF-7 作用的影响,探讨4-AP 能否增强DOC 的作用。方法:用MTT 比色法分析DOC 、4-AP 以及两药联合应用对人乳腺癌细胞MCF-7 增殖的影响;用流式细胞术PI 单染法及Annexin V-FITC/PI双染法检测上述两种药物对人乳腺癌细胞MCF-7 的细胞周期及早期凋亡的影响。结果:DOC 能明显抑制人乳腺癌细胞株MCF-7的增殖,并呈剂量和时间依赖性。4-AP 对MCF-7 细胞增殖亦具有一定的抑制作用,在用药后24h、48h 及72h 的抑制率分别为11.9%±1.7% 、42.1%±3.2% 、44.2%±1.6% 。且5mmol/L 4-AP 可使DOC 的作用增强,使25μ mol/L DOC 对人乳腺癌细胞株MCF-7 最大杀伤作用时间从72h 提前至24h。5 μ mol/L DOC 能够使MCF-7 G2/M期细胞比率明显增加（53.58%±1.44% 与对照组8.83%±0.44% 相比,P<0.01）,使G0/G1 期细胞减少（11.48%±0.14% 与对照组63.89%±0.98% 相比,P<0.01）,说明DOC 主要在G2/M期阻滞MCF-7 细胞的增殖。5mmol/L 4-AP 作用于MCF-7 使其G0/G1 期细胞比率增加,G2/M期细胞明显减少,甚至消失（0.42%±0.17% 与对照组8.83%±0.44% 相比,P<0.05）。 而两药联用可见4-AP 使MCF-7 G2/M期细胞比率有所减少,而G0/G1 期细胞比率有所增加。DOC 单独作用于人乳腺癌细胞株MCF-7 细胞24h 后,能明显增加晚期凋亡和死亡率（由6.97%±0.75% 增加到20.77%±0.75% ,P<0.05）;而两药联合时,与对照组相比,早期凋亡比例由4.60%±0.91% 增加到12.20%±0.82%（P<0.05）,晚期凋亡和死亡细胞比例由6.97%±0.75% 增加到58.42%±0.31%（P<0.05）,提示4-AP（5mmol/L ）能明显增加DOC 诱导的MCF-7 早期凋亡。结论:DOC 和4-AP 分别在G2/M期和G0/G1 期抑制MCF-7 细胞增殖,4-AP 通过促进DOC 诱导细胞凋亡发挥抑制MCF-7 细胞增殖的作用。      

Luteolin inhibits proliferation induced by IGF-1 pathway dependent ERα in human breast cancer MCF-7 cells

The growth of many breast tumors is stimulated by IGF-1, which activates signal transduction pathways inducing cell proliferation. ERα is important in this process. The aim of the study was to investigate relationships in vitro among inhibitory effects of luteolin on the growth of MCF-7 cells, IGF-1 pathway and ERα. Our results showed that luteolin could effectively block IGF-1-stimulated MCF-7 cell proliferation in a dose- and time- dependent manner and block cell cycle progression and induce apoptosis evidenced by the flow cytometric detection of sub-G1DNA content. Luteolin markedly decreased IGF-1-dependent IGF-1R and Akt phosphorylation without affecting Erk1/2 phosphorylation. Further experiments pointed out that ERα was directly involved in IGF-1 induced cell growth inhibitory effects of luteolin, which significantly decreased ERα expression. Knockdown of ERα in MCF-7 cells by an ERα-specific siRNA decreased the IGF-1 induced cell growth inhibitory effects of luteolin. ERα is thus a possible target of luteolin. These findings indicate that the inhibitory effect of luteolin on the growth of MCF-7 cells is via inhibiting IGF-1 mediated PI3K-Akt pathway dependent on ERα expression.