金雀异黄酮对三阴乳腺癌MDA-MB-231细胞凋亡及EGFR/PI3K/Akt通路的影响

目的研究金雀异黄酮(genistein)诱导三阴性乳腺癌MDA-MB-231细胞凋亡及其机制。方法 MTT法观察金雀异黄酮对乳腺癌MDA-MB-231细胞增殖的抑制作用;Hoechst 33258染色观察金雀异黄酮对MDA-MB-231细胞核凋亡形态学的影响;qRT-PCR法观察金雀异黄酮干预MDAMB-231细胞36 h后,EGFR mRNA表达水平的变化;金雀异黄酮干预MDA-MB-231细胞36 h后,Western blot检测凋亡相关蛋白Bcl-2、Bax、caspase-3,EGFR、Akt、p-Akt蛋白的变化;Akt激活剂胰岛素(insulin)、金雀异黄酮单独及联合胰岛素干预乳腺癌MDA-MB-231细胞后,Western blot检测Akt和p-Akt蛋白表达量的变化。结果 MTT结果显示,金雀异黄酮呈时间浓度依赖性抑制乳腺癌MDA-MB-231细胞增殖;Hoechst 33258染色结果显示,金雀异黄酮干预乳腺癌MDAMB-231细胞36 h后细胞核呈现典型凋亡形态学改变;qRTPCR结果显示,经金雀异黄酮干预MDA-MB-231细胞36 h后,EGFR的mRNA表达水平明显下降(P<0.01);Western blot结果显示金雀异黄酮干预乳腺癌MDA-MB-231细胞36 h后,与对照组对比,Bcl-2、EGFR、Akt、p-Akt蛋白表达水平明显下调(P<0.01),Bax、caspase-3蛋白表达水平明显上调(P<0.01),Akt激活剂胰岛素可以明显激活p-Akt(P<0.01),金雀异黄酮可以明显下调被激活的p-Akt(P<0.01)。结论金雀异黄酮能抑制三阴乳腺癌MDA-MB-231细胞生长并诱导其凋亡,其机制可能与抑制EGFR/PI3K/Akt信号通路有关。     

磷脂酰肌醇-3-激酶/丝苏氨酸蛋白激酶信号通路参与核因子-κB受体活化因子配体诱导的MDA-MB-231乳腺癌细胞迁移

目的探讨磷脂酰肌醇-3-激酶/丝苏氨酸蛋白激酶(PI3K/Akt)信号通路在核因子-κB受体活化因子配体(RANKL)诱导的乳腺癌细胞迁移中的作用。方法 Transwell法测定RANKL刺激后MDA-MB-231细胞迁移能力的改变。蛋白印迹法检测MDA-MB-231细胞表面RANK蛋白的表达及RANKL刺激后pAkt及Akt的表达;检测数据用x珚±s表示,采用SPSS 16.0软件进行t检验。结果 MDA-MB-231细胞表达RANK蛋白,RANKL诱导MDA-MB-231细胞迁移能力增强,RANKL的圈套受体骨保护素(OPG)可阻断RANKL诱导的细胞迁移(P<0.01)。RANKL刺激后MDA-MB-231细胞p-Akt表达升高,PI3K抑制剂LY294002抑制RANKL诱导的细胞迁移(P<0.01)。结论 PI3K/Akt信号通路参与RANKL诱导的乳腺癌细胞MDA-MB-231迁移。     

亚砷酸钠抑制PI3K/Akt 信号通路促进乳腺癌细胞凋亡的实验研究

目的　探讨亚砷酸钠促进乳腺癌细胞凋亡的作用及机制。方法　用不同浓度的亚砷酸钠分别作用于乳腺癌细胞（MCF-1/MDA-MB-231）48 h，MTT 法检测细胞增殖情况；用4 μg/mL的亚砷酸钠作用于乳腺癌细胞6 h、12 h、24 h、48 h 和72 h 后，MTT 法检测细胞增殖情况；同时采用流式细胞术检测细胞凋亡情况，Western blot 检测PI3K、p-PI3K、Akt 及p-Akt 的表达水平。结果　0.5 μg/mL、1 μg/mL、2 μg/mL、4 μg/mL、8 μg/mL亚砷酸钠作用48 h 后，MCF-1、MDAMB-231 细胞存活率均明显低于对照组（P<0.05）。MCF-1、MDA-MB-231 细胞经亚砷酸钠作用后细胞凋亡率明显高于对照组（P<0.01）。亚砷酸钠作用后的乳腺癌细胞中PI3K、Akt 的表达水平与对照组比较无显著差异（P>0.05），而p-PI3K、p-Akt的表达水平明显低于对照组（P<0.01）。结论　亚砷酸钠可抑制乳腺癌细胞增殖，且其效应随作用时间的增加而增强；亚砷酸钠可促进乳腺癌细胞凋亡，其作用机制可能与抑制PI3K/Akt 信号通路的激活有关。     

扁蓄苷对人乳腺癌MDA-MB-231细胞凋亡、周期及PI3K/AKT信号通路的影响

目的探讨扁蓄苷对乳腺癌MDA-MB-231细胞的凋亡、周期及PI3K/AKT信号通路的影响。方法以不同浓度的萹蓄苷作用于体外生长至对数期的MDA-MB-231细胞48 h后,采用噻唑蓝染色(MTT)法检测扁蓄苷对细胞增殖的影响,Hoechst 33258染色观察细胞染色质固缩情况,流式细胞术检测细胞周期,Western-blot检测PI3K/AKT信号通路核心蛋白PI3K、p-PI3K、AKT、p-AKT表达水平,RT-PCR技术检测通路下游细胞凋亡蛋白Bcl-2、Bcl-xl及周期相关蛋白CDK2基因表达情况。结果不同浓度的扁蓄苷(6.25、12.5、25、50、100μmol·L~(-1))作用于MDA-MB-231细胞48 h后,细胞增殖活性受到抑制(P <0.01),且具有浓度依赖性;扁蓄苷(12.5、50、100μmol·L~(-1))作用细胞48 h后,细胞核染色质固缩;当扁蓄苷浓度为50μmol·L~(-1)时,S期细胞所占百分比显著增高(P <0.05),当扁蓄苷浓度为100μmol·L~(-1)时,G2/M期细胞所占百分比显著增高(P <0.05);随着扁蓄苷浓度的增加,通路核心位点PI3K、p-PI3K、AKT、p-AKT蛋白表达水平明显降低(P <0.01),细胞凋亡相关蛋白Bcl-2和Bcl-xl、细胞周期蛋白CDK2基因表达水平下调(P <0.05)。结论扁蓄苷可抑制乳腺癌MDA-MB-231细胞增殖,使细胞周期阻滞于S期、G2/M期,并诱导细胞凋亡。其机制可能是通过抑制PI3K/AKT信号通路下调Bcl-2、Bcl-xl、及CDK2基因表达进而诱导人乳腺癌MDA-MB-231细胞凋亡。     

冬凌草甲素通过PI3K/Akt通路诱导MDA-MB-231细胞的凋亡

目的：研究冬凌草甲素对人乳腺癌MDA-MB-231细胞增殖产生的影响,初步探讨其作用机理。方法：体外培养人乳腺癌MDA-MB-231细胞,采用6、12、24μmol/L冬凌草甲素对其进行处理,采用倒置显微镜进行细胞形态学观察,MTT比色法检测细胞存活率,流式细胞术检测细胞凋亡率,Western blotting检测凋亡相关蛋白procaspase-3、PARP及Akt、p-Akt、p-GSK3β表达的变化。结果：冬凌草甲素作用MDA-MB-231细胞24h后,可观察到细胞凋亡的形态学改变,以24μmol/L组最为明显。实验组与对照组相比,细胞存活率显著降低、凋亡率显著升高（P〈0.01）,具有时间和剂量依赖性,凋亡相关蛋白procaspase-3下调,caspase-3底物PARP被逐步剪切,并伴随p-Akt、p-GSK3β蛋白水平下调（P〈0.05）。结论：冬凌草甲素可有效抑制人乳腺癌MDA-MB-231细胞的增殖,诱导其凋亡,机制与PI3K/Akt通路的抑制有关。     

香贝散通过激活AMPK/mTOR信号通路抑制人乳腺癌细胞MCF-7、MDA-MB-231生长

目的 探讨香贝散体外抗乳腺癌作用及其分子机制。方法 体外培养人乳腺癌细胞 MCF-7、MDA-MB-231,给予香贝散 1、2、3、4、5 mg·mL^-1加药处理,对照组不加药。利用 MTT 法和克隆形成实验检测细胞增殖,利用流式细胞术检测细胞凋亡,细胞划痕和细胞侵袭实验检测细胞迁移和侵袭能力,借助吖啶橙染色法观察细胞自噬,借助转录组测序技术探索香贝散诱导乳腺癌细胞死亡的作用机制,并采用 Western blotting 法检测 AMP 依赖的蛋白激酶（AMPK）、哺乳动物雷帕霉素靶蛋白（mTOR）、LC-3、Beclin-1 蛋白表达水平。结果 与对照组比较,香贝散显著抑制人乳腺癌 MCF-7、MDA-MB-231 细胞活力（P＜0.05、0.001）,48 h 半数抑制浓度（IC₅₀）分别为 2.344、1.961 mg·mL^-1,且具有时间、浓度相关性;显著抑制 MCF-7、MDA-MB-231 细胞的集落形成能力;显著诱导 MCF-7、MDA-MB-231 细胞凋亡（P＜0.001）;明显抑制人乳腺癌 MCF-7、MDA-MB-231 细胞的体外迁移能力和侵袭能力;吖啶橙染色实验结果提示香贝散能够诱导 MCF-7、MDA-MB-231 细胞发生自噬,Western blotting 实验结果显示香贝散能够显著上调 MCF-7、MDA-MB-231 细 胞 中 自 噬 关 键 蛋 白 Beclin-1 和 LC3-Ⅱ的表达（P＜0.01、0.001）;转录组测序技术发现差异基因变化最明显的通路包括 mTOR 信号通路、自噬信号通路等 ,Western blotting 实验结果显示香贝散显著下调 mTOR 的磷酸化水平（P＜0.001）,显著上调 AMPK 的磷酸化水平（P＜0.001）。结论 香贝散能够显著抑制人乳腺癌细胞的增殖、迁移、侵袭能力,能够诱导凋亡和自噬的发生,激活 AMPK/mTOR 信号通路可能是其重要机制。     

紫草素通过PI3K/Akt通路促进人乳腺癌MCF-7细胞自噬

目的研究紫草素(Shikonin)对人乳腺癌MCF-7细胞自噬的影响及其作用机制。方法 CCK-8法检测紫草素处理人乳腺癌MCF-7细胞24、48 h细胞的存活率,Western blot方法检测紫草素处理24 h和48 h时LC3、p62、PI3K、Akt、p-PI3K、p-Akt蛋白水平。结果 1μmol.L-1紫草素处理细胞48 h以及2.5、5μmol.L-1紫草素处理MCF-7细胞24 h和48 h时,MCF-7细胞的活力受到明显抑制,LC3-Ⅱ/LC3-Ⅰ值增加,p62表达减少,总PI3K、Akt、p-PI3K、p-Akt均减少。结论紫草素促进乳腺癌MCF-7细胞自噬,其作用机制可能与PI3K/Akt通路受到抑制有关。     

氯喹对三阴乳腺癌MDA-MB-231细胞增殖的影响及其机制

目的观察氯喹对三阴乳腺癌MDA-MB-231细胞增殖的影响,并探讨其机制。方法用氯喹20,40和80μmol·L~(-1)分别处理MDA-MB-231细胞24和48 h,采用CCK-8法和细胞克隆形成实验检测细胞增殖,流式细胞术检测细胞周期和凋亡,Western印迹法检测细胞周期相关蛋白即细胞周期蛋白D3、细胞周期蛋白依赖性激酶2(CDK2)和CDK4,细胞凋亡相关蛋白即活化胱天蛋白酶3和活化聚腺苷二磷酸-核糖聚合酶(PARP)及自噬标志蛋白即自噬微管相关蛋白轻链3B(LC3B)和自噬底物SQSTM1表达水平。结果氯喹20,40和80μmol·L~(-1)与MDA-MB-231细胞作用24和48 h后,均能有效抑制细胞增殖(P<0.01)。与细胞对照组相比,氯喹20和40μmol·L~(-1)处理24 h,G_0/G_1期细胞百分比显著增高(P<0.01);80μmol·L~(-1)组G_2/M期细胞百分比升高(P<0.01),且细胞凋亡率增加(P<0.01)。处理48 h,与细胞对照组相比,氯喹用药3组细胞凋亡率均显著升高(P<0.05)。氯喹3组处理24 h,与细胞对照组相比,细胞周期蛋白D3、CDK2和CDK4表达水平降低(P<0.01),活化胱天蛋白酶3和活化PARP表达增强(P<0.01),LC3B和SQSTM1表达水平显著升高(P<0.01)。结论氯喹可通过抑制MDA-MB-231细胞自噬、阻滞细胞周期进程并促进细胞凋亡而抑制其增殖。     

四氢姜黄素增强姜黄素抗乳腺癌作用机制初探

目的探讨口服姜黄素体内抗乳腺癌的作用及机制。即其主要代谢产物——四氢姜黄素增强姜黄素抑制乳腺癌细胞生长的作用及机制。方法用MTT法及克隆形成法检测姜黄素与四氢姜黄素单独或联合作用对人乳腺癌MCF-7、MDAMB-231细胞增殖的影响;用PI染色结合流式细胞术检测姜黄素和四氢姜黄素单独或联合作用对人乳腺癌MCF-7、MDA-MB-231细胞周期分布的影响;用Annexin V/PI双染结合流式细胞术检测姜黄素和四氢姜黄素单独或联合作用对人乳腺癌MCF-7、MDA-MB-231细胞凋亡的影响;用Western印迹法检测姜黄素和四氢姜黄素单独或联合作用后人乳腺癌MCF-7、MDA-MB-231细胞中凋亡相关蛋白Fas、FADD、c FLIP、活化胱天蛋白酶3/8及PARP的表达水平。结果 10～40μmol·L~(-1)的四氢姜黄素对于两种人乳腺癌细胞生长抑制作用较弱,而相同剂量的姜黄素可明显抑制乳腺癌细胞生长,两药联用对于MCF-7和MDA-MB-231细胞的生长抑制作用随时间的延长和药物浓度的增加而增加,且对肿瘤细胞的抑制作用明显强于对应的单药处理组,且多个剂量组合的CI值小于1。与对照组相比,四氢姜黄素及姜黄素单加或联用均不影响MCF-7及MDA-MB-231细胞的周期分布,但却发现姜黄素或四氢姜黄素联合姜黄素处理48及72 h后,两种细胞中sub-G1期细胞凋亡峰显著上调,且两药联用组的细胞凋亡比率显著大于姜黄素单加组。进一步Annexin V/PI双染结合流式细胞术的结果显示,与对照组相比,四氢姜黄素组没有凋亡产生,姜黄素组可随时间依赖性的诱导两种乳腺癌细胞发生凋亡,而四氢姜黄素与姜黄素联用后,细胞凋亡比率较姜黄素组有了极显著的增加。与对照组相比,姜黄素可上调Fas表达,且明显减少原型胱天蛋白酶3、胱天蛋白酶8和PARP的蛋白表达,相反,剪切形式胱天蛋白酶3、胱天蛋白酶8和PARP明显增加,同时下调抗凋亡蛋白cFLIP的表达,但四氢姜黄素对于以上蛋白作用并不明显,而四氢姜黄素与姜黄素共同处理后可以明显增加姜黄素对于以上凋亡相关蛋白表达水平的改变。结论四氢姜黄素能够在体外增强姜黄素诱导的乳腺癌细胞凋亡,提示姜黄素及其体内代谢产物共同发挥抗乳腺癌作用,且其代谢产物可能具有增效作用。     

土槿乙酸诱导的卵巢癌细胞HO-8910自噬及其机制

目的探讨土槿乙酸诱导的人卵巢癌细胞系HO-8910细胞自噬蛋白的表达及PI3K/Akt信号转导通路的变化,以及自噬特异性抑制剂3-甲基腺嘌呤(3-MA)和自噬激动剂雷帕霉素(RAPA)对自噬相关蛋白的影响。方法不同浓度的土槿乙酸作用HO-8910细胞,采用台盼蓝染色检测细胞的存活率,Western blot分析检测自噬相关蛋白及PI3K/Akt通路相关蛋白的变化,分别用3-MA和RAPA处理HO-8910细胞后检测自噬相关蛋白的变化。结果土槿乙酸能够诱导卵巢癌细胞HO-8910自噬,增加LC3-Ⅱ和自噬调节因子Beclin-1的表达;3-MA可以抑制土槿乙酸诱导的HO-8910细胞自噬相关蛋白的表达,而RAPA促进了土槿乙酸诱导的HO-8910细胞自噬相关蛋白的表达,且土槿乙酸能抑制PI3K/Akt通路蛋白的表达。结论土槿乙酸可通过抑制PI3K/Akt通路诱导HO-8910细胞自噬。     

Berberine inhibits growth of the breast cancer cell lines MCF-7 and MDA-MB-231

The effects of berberine on the behavior of breast tumors have not yet been established. To determine whether this compound is useful in the treatment of breast cancer, we analyzed the impact of berberine on the human breast cancer cell lines MCF-7 and MDA-MB-231 cells. Berberine was added to proliferating MCF-7 and MDA-MB-231 cells in culture. Following treatment, changes in cell growth characteristics such as proliferation, cell cycle duration, and the degree of apoptosis were assayed. Following berberine treatment, a time-dependent reduction in proliferation was observed in both cell lines at differing concentrations: 20 microM for MCF-7 and 10 microM for MDA-MB-231 cells. Annexin V staining showed an increase in apoptosis in both cell lines of 31 % in MCF-7 and 12 % in MDA-MB-231 cells compared to their respective controls. In addition, 12 % of the MCF-7 cells were arrested at G0/G1, compared to 62 % of control cells. These results demonstrate that treatment with berberine inhibits growth in both MDA-MB-231 and MCF-7 cells. In addition, they show that this partly occurs through the induction of apoptosis in MDA-MB-231 cells, and through both cell cycle arrest and induction of apoptosis in MCF-7 cells. Thus, berberine may be a novel therapeutic drug for breast cancer.     

Contribution of nucleophosmin overexpression to multidrug resistance in breast carcinoma

Multidrug resistance (MDR) is a serious obstacle in breast cancer patients which limits chemotherapeutic drugs application. Our previous study confirmed that overexpression of nucleophosmin (NPM) was closely related to MDR in methotrexate-resistant breast cancer cells (MCF-7/MTX), and NPM could be a potential therapeutic target for chemoresistance. In this work, we aim to investigate NPM-mediated resistance mechanism in breast carcinoma. The NPM level was strongly positive in breast carcinoma tissues compared with adjacent normal samples, which was associated with lymph node metastasis. We found abnormal expression of NPM activated PI3K/Akt pathway and affected downstream apoptosis factors. Then, NPM level was attenuated by RNA interfering technology, the sensitivity of MCF-7/MTX cells to methotrexate was obviously increased, factor level of mitochondria apoptosis pathway was significantly augmented, and Akt phosphorylation was inhibited. Furthermore, examination of Akt and NPM level demonstrated that Akt inhibitor MK-2206 sensitised resistant cells to methotrexate and induced MCF-7/MTX cell apoptosis by PI3K/Akt pathway and mitochondria apoptosis pathway. These suggested NPM-induced resistance and anti-apoptosis were required for Akt activity. NPM has a crucial function in MDR of breast cancer through influencing Akt activity and resistant cell apoptosis, and it could be expected to become a therapeutic target for chemoresistance in breast cancer.     

RIP3 overexpression sensitizes human breast cancer cells to parthenolide in vitro via intracellular ROS accumulation

Aim： Receptor-interacting protein 3 （RIP3） is involved in tumor necrosis factor receptor signaling, and results in NF-KB-mediated prosurvival signaling and programmed cell death. The aim of this study was to determine whether overexpression of the RIP3 gene could sensitize human breast cancer cells to parthenolide in vitro. Methods： The expression of RIP3 mRNA in human breast cancer cell lines （MCF-7, MDA-MB-231, MDA-MB-435 and T47D） was detected using RT-PCR. Both MDA-MB-231 and MCF-7 cells were transfected with RIP3 expression or blank vectors via lentivirus. Cell viability was measured with MTT assay; intracellular ROS level and cell apoptosis were analyzed using flow cytometry. Results： RIP3 mRNA expression was not detected in the four human breast cancer cell lines tested. However, the transfection induced higher levels of RIP3 protein in MCF-7 and MDA-MB-231 cells. Furthermore, overexpression of RIP3 decreased the IC50 values of parthenolide from 17.6 to 12.6 μmol/L in MCF-7 cells, and from 16.6 to 9.9 μmol/L in MDA-MB-231 cells. Moreover, overexpression of RIP3 significantly increased parthenolide-induced apoptosis and ROS accumulation in MCF-7 and MDA-MB-231 cells. Pretreatment with N-acetyl-cysteine abrogated the increased sensitivity of RIP3-transfected MCF-7 and MDA-MB-231 cells to parthenolide. Conclusion： Overexpression of RIP3 sensitizes MCF-7 and MDA-MB-231 breast cancer cells to parthenolide in vitro via intracellular ROS accumulation.     

Cytotoxicity,cell cycle arrest,and apoptosis in breast cancer cell lines exposed to an extract of the seed kernel of Mangifera pajang (bambangan)

An extract of Mangifera pajang kernel has been previously found to contain a high content of antioxidant phytochemicals. The present research was conducted to investigate the anticancer potential of this kernel extract. The results showed that the kernel crude extract induced cytotoxicity in MCF-7 (hormone-dependent breast cancer) cells and MDA-MB-231 (non-hormone dependent breast cancer) cells with IC50 values of 23 and 30.5 μg/ml, respectively. The kernel extract induced cell cycle arrest in MCF-7 cells at the sub-G1 (apoptosis) phase of the cell cycle in a time-dependent manner. For MDA-MB-231 cells, the kernel extract induced strong G2-M arrest in cell cycle progression at 24 h, resulting in substantial sub-G1 (apoptosis) arrest after 48 and 72 h of incubation. Staining with Annexin V-FITC and propidium iodide revealed that this apoptosis occurred early in both cell types, 36 h for MCF-7 cells and 24 h for MDA-MB-231cells, with 14.0% and 16.5% of the cells respectively undergoing apoptosis at these times. This apoptosis appeared to be dependent on caspase-2 and -3 in MCF-7 cells, and on caspase-2, -3 and -9 in MDA-MB-231 cells. These findings suggest that M. pajang kernel extract has potential as a potent cytotoxic agent against breast cancer cell lines.     

Inhibition of EGF/EGFR activation with naphtho[1,2-b]furan-4,5-dione blocks migration and invasion of MDA-MB-231 cells

Naphtho[1,2-b]furan-4,5-dione (NFD), a bioactive component of Avicennia marina, has been demonstrated to display anti-cancer activity. Activation of epidermal growth factor receptor (EGFR)-induced signaling pathway has been correlated with cancer metastasis in various tumors, including breast carcinoma. We use EGF as a metastatic inducer of MDA-MB-231 cells to investigate the effect of NFD on cell migration and invasion. NFD suppressed EGF-mediated protein levels of c-Jun and c-Fos, and reduced MMP-9 expression and activity, concomitantly with a marked inhibition on cell migration and invasion without obvious cellular cytotoxicity. NFD abrogated EGF-induced phosphorylation of EGF receptor (EGFR) and phosphatidylinositol 3-kinase (PI3K)/Akt. The specific PI3K inhibitor, wortmannin, blocked significantly EGF-induced cell migration and invasion. Furthermore, the EGFR inhibitor AG1478 inhibited EGF-induced MMP-9 expression, cell migration and invasion, as well as the activation of PI3K/Akt, suggesting that PI3K/Akt activation occur downstream of EGFR activation. These findings suggest that NFD inhibited the EGF-induced invasion and migration of MDA-MB-231 cells via EGFR-dependent PI3K/Akt signaling, leading to the down-regulation of MMP-9 expression. These results provide a novel mechanism to explain the role of NFD as a potent anti-metastatic agent in MDA-MB-231 cells.     

Germacrone inhibits the proliferation of breast cancer cell lines by inducing cell cycle arrest and promoting apoptosis

Traditional medicinal herbs are an untapped source of potential pharmaceutical compounds. This study aims to determine whether the proliferation of breast cancer cell lines could be inhibited by germacrone, a natural product isolated from Rhizoma curcuma. Germacrone treatment significantly inhibited cell proliferation, increased lactate dehydrogenase (LDH) release, and induced mitochondrial membrane potential (ΔΨm) depolarization in both MCF-7 and MDA-MB-231 cells in a dose-dependent manner. Germacrone induced MDA-MB-231 and MCF-7 cell cycle arrest at the G0/G1 and G2/M phases respectively and induced MDA-MB-231 cell apoptosis. Furthermore, germacrone treatment significantly increased Bok expression and cytochrome c release from mitochondria without affecting Bcl-2, Bcl-xL, Bax, and Bim protein expressions. In addition, germacrone treatment induced caspase-3, 7, 9, PARP cleavage. We concluded that germacrone inhibited the proliferation of breast cancer cell lines by inducing cell cycle arrest and apoptosis through mitochondria-mediated caspase pathway. These results might provide some molecular basis for the anti-tumor activity of Rhizoma curcuma.     

Anti-tumor potential of 15,16-dihydrotanshinone I against breast adenocarcinoma through inducing G1 arrest and apoptosis

Chemotherapeutic drugs are usually designed to induce cancer cell death via cell cycle arrest and/or apoptosis pathways. In this study, we used the chemical drug 15,16-dihydrotanshinone I (DHTS) to inhibit breast cancer cell proliferation and tumor growth, and investigate the underlying molecular mechanisms. Human breast cancer cell lines MCF-7 and MDA-MB-231 were both used in this study, and DHTS was found to significantly decrease cell proliferation by a dose-dependent manner in both cells. Flow cytometry indicated that DHTS induced G1 phase arrest in synchronous MCF-7 and MDA-MB-231 cells. When analyzing the expression of cell cycle-related proteins, we found that DHTS reduced cyclin D1, cyclin D3, cyclin E, and CDK4 expression, and increased CDK inhibitor p27 expression in a dose-dependent manner. In addition, DHTS inhibited the kinase activities of CDK2 and CDK4 by an immunocomplex kinase assay. In addition, DHTS also induced apoptosis in both cells through mainly mitochondrial apoptosis pathways. We found that DHTS decreased the anti-apoptotic protein Bcl-xL level and increased the loss of mitochondria membrane potential and the amount of cytochrome c released. Moreover, DHTS activated caspase-9, caspase-3, and caspase-7 and caused cell apoptosis. The fact that DHTS-induced apoptosis could be blocked by pretreating cells with pan-caspase inhibitor confirmed that it is mediated through activation of the caspase-3-dependent pathway. In a nude mice xenograft experiment, DHTS significantly inhibited the tumor growth of MDA-MB-231 cells. Taken together, these results suggest that DHTS can inhibit human breast cancer cell proliferation and tumor growth, and might have potential chemotherapeutic applications.