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。     

黄连碱对人乳腺癌MDA-MB-231细胞周期和增殖的作用及其机制

目的 探讨黄连碱对人乳腺癌细胞株MDA-MB231细胞周期和增殖的作用及相关机制.方法 MTT法和瑞-姬氏染色法分别检测黄连碱对MDA-MB-231细胞增殖的影响,流式细胞术检测细胞周期分布,RT-PCR检测细胞周期相关基因包括细胞周期蛋白依赖性激酶4(CDK4)、CDK6、p21及p27mRNA的表达变化.结果 黄连碱可明显抑制MDA-MB-231细胞的增殖;黄连碱处理细胞后G0/G1期细胞比例减少,而S期和G2/M期细胞比例增高(P＜0.05或P＜0.01);黄连碱可上调p21 mRNA的表达、下调CDK4 mRNA和CDK6 mRNA的表达(P＜0.01),而对p27 mRNA水平无显著影响.结论 黄连碱在体外能通过诱导S期及G2/M期周期阻滞来抑制MDA-MB-231细胞的增殖;其机制可能与p21mRNA表达上调导致CDK4 mRNA及CDK6 mRNA减少有关.     

芦荟大黄素对高转移乳腺癌细胞MDA-MB-231体外转移潜能的影响

目的研究芦荟大黄素(Aloe emodin,AE)对人高转移乳腺癌细胞MDA-MB-231体外转移潜能的影响及其作用机制。方法 MTT法检测AE对MDA-MB-231细胞增殖的抑制作用;Transwell chamber法检测AE对MDA-MB-231细胞侵袭重组基底膜能力和趋化性运动能力的影响;RT-PCR、Western blot法检测AE对MDA-MB-231细胞黏着斑激酶(FAK)mRNA和蛋白表达的影响。明胶酶谱法检测MDA-MB-231细胞分泌的基质金属蛋白酶-9(MMP-9)活性。结果 80μmol·L-1 AE抑制MDA-MB-231细胞体外侵袭重组基底膜能力、趋化性运动能力,其抑制率分别为(52.98±5.46)%,(45.88±8.51)%。作用于MDA-MB-231细胞24 h后,AE下调FAK mRNA和蛋白表达,下调MDA-MB-231细胞分泌MMP-9。结论 AE抑制MDA-MB-231细胞体外侵袭能力、趋化性运动能力,其作用机制与其下调FAK表达和MMP-9的分泌有关。     

阿帕替尼调控上皮间质转化抑制三阴性乳腺癌MDA-MB-231细胞侵袭

目的探讨阿帕替尼对人三阴性乳腺癌MDA-MB-231细胞侵袭作用的影响。方法 MTT法检测不同浓度的阿帕替尼(1、 2、 4、 8、 16μmol·L~(-1))作用于乳腺癌MDA-MB-231细胞48 h的细胞毒性,并采用Bliss法计算半数抑制浓度(IC50); Annexin V-FITC/PI流式细胞术检测阿帕替尼对MDA-MB-231细胞凋亡的影响;Transwell实验检测阿帕替尼对MDA-MB-231细胞侵袭能力的影响;Western blot检测阿帕替尼对上皮间质转化(EMT)标志性蛋白上皮钙黏素、神经钙黏素及波形蛋白表达的影响。结果 1、 2、4、 8、 16μmol·L~(-1)阿帕替尼可显著抑制MDA-MB-231细胞的增殖,增殖抑制率分别为(38.38±3.33)%、(53.17±4.31)%、(62.09±6.21)%、(80.97±7.50)%和(98.54±9.75)%。阿帕替尼作用48 h对MDA-MB-231细胞的IC50为1.96μmol·L~(-1)。与空白对照组相比,阿帕替尼可显著诱导MDA-MB-231细胞凋亡,显著抑制MDA-MB-231细胞侵袭基底膜的能力(P<0.05);阿帕替尼还可显著上调MDA-MB-231细胞上皮钙黏素的表达,下调神经钙黏素及波形蛋白的表达(P <0.05)。结论阿帕替尼可能通过调控EMT进而发挥抗三阴性乳腺癌MDA-MB-231细胞侵袭作用。     

野马追总黄酮的体内外抗乳腺癌活性及机制研究

目的 探究野马追总黄酮(TFE)的体内外抗乳腺癌活性及相关的作用机制。方法 MTT法检测TFE对乳腺癌细胞(MCF-7、T47D、MDA-MB-231、MDA-MB-468)和人正常乳腺上皮细胞MCF-10A增殖的影响;流式细胞术检测TFE对乳腺癌细胞周期和凋亡的影响;吖啶橙(AO)染色法检测TFE对细胞自噬的影响;Western blot检测细胞周期、凋亡、自噬相关蛋白的变化,以及PI3K/Akt信号通路相关蛋白的变化;建立MDA-MB-231细胞的裸鼠移植瘤模型,观察TFE的体内抗肿瘤活性。结果 TFE能明显抑制乳腺癌细胞增殖,并呈剂量依赖性,而对人正常乳腺上皮细胞无显著的抑制作用;TFE能增加G₂/M期细胞比例,上调p-cdc-2蛋白表达,下调cdc-2和Cyclin B1蛋白表达;TFE能显著增加乳腺癌细胞凋亡比例,上调促凋亡蛋白Bad和Bax表达,下调抗凋亡蛋白Bcl-2表达;TFV能够诱导乳腺癌细胞产生自噬,自噬相关蛋白LC3-II表达上升,p62表达降低;TFE能够抑制显著抑制PI3K和Akt的磷酸化水平;TFE能够在体内抑制裸鼠肿瘤的体积。结论 TFE通过抑制PI3K/Akt信号通路,阻滞细胞周期、诱导凋亡和自噬,进而在体内外抑制乳腺癌细胞的生长。     

NF-κB和MAPK信号通路参与金雀异黄酮诱导乳腺癌MDA-MB-231细胞凋亡的体外研究

目的探讨金雀异黄酮(genistein)诱导人乳腺癌MDA-MB-231细胞凋亡的可能机制。方法采用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;集落形成法观察金雀异黄酮对MDA-MB-231细胞集落形成能力的影响;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及NF-κB、ERK、p-ERK、JNK、p-JNK蛋白的表达。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MDAMB-231细胞增殖;集落形成实验结果显示,金雀异黄酮能明显抑制乳腺癌MDA-MB-231细胞的集落形成(P<0.05);Western blot结果显示,金雀异黄酮干预乳腺癌MDA-MB-231细胞36 h后,与对照组相比,Bcl-2、NF-κB、p-ERK蛋白表达水平明显下调(P<0.05),Bax、caspase-3、p-JNK蛋白表达水平明显上调(P<0.05)。结论金雀异黄酮能抑制乳腺癌MDA-MB-231细胞生长,且能诱导其凋亡,其机制可能与抑制NF-κB、ERK,激活JNK信号转导通路有关。     

刺五加皂苷B/E对乳腺癌MDA-MB-231细胞迁移能力的影响及作用机制研究

目的：探讨刺五加皂苷B/E对乳腺癌MDA-MB-231细胞迁移能力的影响及作用机制。方法：CCK-8检测刺五加皂苷B/E对乳腺癌MDA-MB-231细胞增殖能力的影响;细胞划痕实验检测刺五加皂苷B/E对乳腺癌MDA-MB-231细胞迁移的影响;Transwell实验检测刺五加皂苷B/E对乳腺癌MDA-MB-231细胞侵袭的影响;试剂盒检测刺五加皂苷B/E对乳腺癌MDA-MB-231细胞乳酸分泌的影响;PCR检测刺五加皂苷B/E对乳腺癌MDA-MB-231细胞HK、PFK和Glut4基因表达的影响;Western Blot法检测刺五加皂苷B/E对乳腺癌MDA-MB-231细胞HK、PFK和Glut4蛋白表达的影响。结果：刺五加皂苷B/E 25、50、100、200 μmol·L-1剂量不抑制MDA-MB-231细胞增殖;刺五加皂苷B/E 100、200 μmol·L-1能够抑制MDA-MB-231细胞迁移;刺五加皂苷B/E 50、100、200 μmol·L-1能够抑制MDA-MB-231细胞侵袭和乳酸分泌,也能够降低MDA-MB-231细胞有氧糖酵解中相关蛋白HK、PFK、Glut4的表达。结论：刺五加皂苷B/E能够抑制乳腺癌MDA-MB-231细胞的迁移、侵袭,其机制可能与抑制肿瘤细胞糖酵解有关。     

双氢青蒿素对人乳腺癌细胞MDA-MB-231周期的作用

目的研究双氢青蒿素（alpha-Dihydroartemisinin,DHA）对人乳腺癌细胞MDA-MB-231周期的影响。方法M1Tr法测定DHA对人乳腺癌MDA-MB-231细胞抑制率,流式细胞术检测细胞周期分布,免疫组化方法测定cyclinBl与cdc2蛋白的表达。结果DHA体外能够明显抑制人乳腺癌MDA-MB-231细胞的生长,并呈现一定的时间一剂量效应,24、48和72h的Ic50值分别为220．5、142．1和124．3μmol·L^-1;DHA作用MDA-MB-231细胞48h后,流式细胞术检测到G0/Gl期和s期细胞明显减少、G2/M期细胞显著增多,细胞周期蛋白cyclinBl与cdc2表达下调。结论DHA对人乳腺癌MDA-MB-231细胞有显著的抑制作用,其作用机制可能是通过下调周期蛋白cyclinBl与cdc2的表达诱导细胞阻滞于G2/M期。     

应用 RNA 干扰技术下调 ANXA3表达的 MDA-MB-231乳腺癌细胞株的建立

目的：建立针对膜联蛋白A3（Annexin A3, ANXA3）的shRNA稳定转染的乳腺癌细胞株MDA-MB-231,为后续进一步研究奠定基础。方法荧光定量RT-PCR及western blot方法检测两种乳腺癌细胞株（ MDA-MB-231及MCF-7）中ANXA3 mRNA及蛋白表达水平。构建沉默ANXA3基因的shRNA质粒3个（ ANXA3-sh1-3）及阴性对照质粒,脂质体法转染人乳腺癌细胞MDA-MB-231;选出ANXA3沉默效果最好的干扰质粒做后续实验。嘌呤霉素筛选出稳定转染细胞;Western blot 方法检测转染后细胞中ANXA3蛋白表达水平。结果 MDA-MB-231细胞中 ANXA3 mRNA及蛋白表达水平显著高于MCF-7中的表达（ P ＜0 k．05）;成功构建3个针对ANXA3基因的shRNA质粒;转染ANXA3-sh1～3及阴性对照质粒后MDA-MB-231细胞中ANXA3 mRNA表达水平分别为（0．0196±0．0002）、（0．0085±0．0002）、（0．0220±0．0035）、（0．0661±0．0057）,未转染的MDA-MB-231细胞中ANXA3 mRNA表达水平为（0．0692±0．0050）,脂质体组MDA-MB-231细胞中ANXA3 mRNA表达水平为（0．0652±0．0118）,ANXA3-sh2对MDA-MB-231细胞中ANXA3 mRNA沉默效率最高,达87．72％,因此后续实验选择ANXA3-sh2;嘌呤霉素筛选出稳定转染细胞分别命名为MDA-MB-231-Sh及MDA-MB-231-NC细胞。 Western blot检测结果显示,MDA-MB-231-Sh细胞中ANXA3蛋白显著低于MDA-MB-231及MDA-MB-231-NC细胞中的表达（ P ＜0．01）。结论 MDA-MB-231细胞较MCF-7细胞高表达ANXA3,成功的建立了稳定下调ANXA3表达的乳腺癌细胞株MDA-MB-231,为后续进一步研究ANXA3的表达及特性打下基础。     

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。     

三氧化二砷对MDA-MB-231细胞增殖、凋亡的影响

目的观察不同浓度的三氧化二砷对三阴性乳腺癌MDA-MB-231细胞增殖、凋亡的影响。方法噻唑蓝(MTT)比色法检测不同浓度(0.2、0.4、0.6、0.8、1.0μmol.L-1)的三氧化二砷作用于三阴性乳腺癌MDA-MB-231细胞24、48、72 h后的细胞增殖率,Western blot检测不同浓度的三氧化二砷作用于MDA-MB-231细胞24 h的PCNA水平。结果不同浓度的三氧化二砷作用于三阴性乳腺癌MDA-MB-231细胞24、48、72 h后,随着时间的推移和浓度的升高,细胞增殖抑制率增加,有浓度和时间依赖性,以1.0μmol.L-1三氧化二砷作用最明显,Western blot检测显示,与对照组比较,随着浓度的升高,PCNA蛋白降低,其中以1.0μmol.L-1三氧化二砷作用后最明显。结论三氧化二砷能促进MDA-MB-231细胞的凋亡,其机制可能与下调PCNA表达的促凋亡途径有关。     

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.     

Ganoderic acids suppress growth and angiogenesis by modulating the NF-kappaB signaling pathway in breast cancer cells

It has been demonstrated that ganoderma acids suppress growth, angiogenesis and invasiveness of highly invasive and metastatic breast cancer cells in vitro and vivo. However, the mechanism of action of ganoderma acids in breast cancer remains unknown. In the present study, we looked into the effect of ganoderic acid Me (GA-Me) on cellular phenotypes and tumor growth in the MDA-MB-231 breast cancer cell line. The results indicated the GA-Me inhibited nuclear factor kappaB (NF-κB) activity at 24 h in MDA-MB-231 cells. When MDAMB- 231 cells were stimulated with tumor necrosis factor-alpha (TNF-α), the inhibitory effects of GA-Me were still maintained. We demonstrated that GA-Me inhibited proliferation and invasion and induced apoptosis in MDA-MB-231 cells via suppressing the NF-κB activity. However, GA-Me did not inhibit the phosphorylation and degradation of IkappaB-α (IkB-α). GA-Me down-regulated the expression of various NF-κB-regulated genes including genes involved in cell proliferation (c-Myc and cyclin D1), anti-apoptosis (Bcl-2), invasion (MMP-9) and angiogenesis (VEGF, interleukin (IL)-6 and -8). I.P. administration of GA-Me inhibited tumor growth of MDA-MB-231 cells in vivo. Our results demonstrated that GA-Me inhibited proliferation, angiogenesis, invasion and induced apoptosis in MDA-MB-231 cells via suppressing NF-κB activity and the expression profile of its downstream genes. These findings provide evidence for a novel role of GA-Me in the prevention and treatment of breast cancer by its ability to modulate the NF-κB signaling pathway.     

Inhibition of the mevalonate pathway and activation of p38 MAP kinase are independently regulated by nitrogen-containing bisphosphonates in breast cancer cells

Bisphosphonates are widely used inhibitors of bone resorption. They also inhibit the growth of various cancer cells in vitro, but the clinical significance of this effect is unclear. The cancer growth inhibitory effects of nitrogen-containing bisphosphonates, (i.e. zoledronate) have been attributed to their ability to inhibit the mevalonate pathway. We have shown that bisphosphonates also induce p38 activation, which signals resistance against the drug-induced growth inhibition through an unknown mechanism. We show here that zoledronate induces a G1/S cell cycle arrest in human MDA-MB-231 breast cancer cells. Furthermore, p38 inhibitor augments bisphosphonate-induced growth inhibition by inducing an additional G2-phase cell cycle arrest. We also show that the nitrogen-containing bisphosphonate-induced effects on p38 phosphorylation occur before accumulation of unprenylated Rap1A or Rac1 activation. Geranylgeranyl pyrophosphate, an end-product of the mevalonate pathway, reversed the accumulation of unprenylated Rap1A but not phosphorylation of p38. Geranylgeranyl pyrophosphate also reversed n-BP induced growth inhibition, but the completeness of this reversal was nitrogen-containing bisphosphonate concentration dependent. Also mevastatin induced the accumulation of unprenylated Rap1A, but it did not induce p38 phosphorylation. In conclusion, our results suggest that in addition to the previously reported effects on apoptosis, nitrogen-containing bisphosphonates also inhibit the growth of MDA-MB-231 breast cancer cells by inducing G1/S cell cycle arrest. The bisphosphonate-induced p38 activation signals for resistance against these drugs, by promoting progression through the G2/M-checkpoint. Of these pathways only growth inhibition is mediated via inhibition of the mevalonate pathway in MDA-MB-231 cells. Combining p38 inhibitors with bisphosphonates may result in increased anti-cancer efficacy.     

Differential effects of Ca(2+) on bisphosphonate-induced growth inhibition in breast cancer and mesothelioma cells

Bisphosphonates are widely clinically used inhibitors of bone resorption. Pre-clinical studies indicate that bisphosphonates also inhibit the growth of various cancer cells in vitro, but their in vivo anti-cancer activity varies greatly, depending on the tumor type. We compared the various cellular effects of bisphosphonates in breast cancer and mesothelioma cells, with differences in growth inhibition responses to bisphosphonate-treatment in vivo. We show that the growth inhibitory effects of nitrogen-containing bisphosphonates are significantly affected by excess Ca(2+) in a cell- and bisphosphonate-specific fashion. Furthermore, excess pyrophosphate-resembling bisphosphonates prevent nitrogen-containing-bisphosphonate-induced accumulation of unprenylated Rap1A, p38 phosphorylation and growth inhibition in human MDA-MB-231 breast cancer and mouse AB-12 mesothelioma cells. For some, but not all tested, pyrophosphate-resembling bisphosphonate: nitrogen-containing bisphosphonate combinations these results may be partially explained by the ability of the excess pyrophosphate-resembling bisphosphonates to chelate Ca(2+). In mice, subcutaneous AB-12 and MDA-MB-231 tumors exhibit positive staining for Ca(2+) minerals, as revealed with Von Kossa stainings. We further show that the AB-12 tumors accumulate significantly more of the bone scanning bisphosphonate, Tc99m-medronate, as compared with MDA-MB-231 tumors. In conclusion, our results suggest that Ca(2+) regulates the growth inhibitory effects of bisphosphonates in a target cell and drug-specific fashion. These findings may be of physiological relevance since many tumor types are calcified. They further suggest that bisphosphonates can accumulate in tumors that are growing at the visceral sites and that differences in tumor accumulation of bisphosphonates may regulate their in vivo sensitivity to these drugs.     

VI-14, a novel flavonoid derivative, inhibits migration and invasion of human breast cancer cells

It has been well characterized that flavonoids possess pronounced anticancer potentials including anti-angiogenesis, anti-metastasis, and pro-apoptosis. Herein, we report, for the first time, that VI-14, a novel flavonoid derivative, possesses anti-cancer properties. The purpose of this study is to investigate the anti-migration and anti-invasion activities of VI-14 in breast cancer cells. Our data indicate that VI-14 inhibits adhesion, migration and invasion of MDA-MB-231 and MDA-MB-435 human breast cancer cells. MDA-MB-231 cells treated with VI-14 display reduced activities and expressions of ECM degradation-associated proteins including matrix metalloproteinase 2 (MMP-2) and 9 (MMP-9) at both the protein and mRNA levels. Meanwhile, VI-14 treatment induces an up-regulated expression of tissue inhibitor of metalloproteinase 1 (TIMP-1) and 2 (TIMP-2) in MDA-MB-231 cells. Western blotting results show that phosphorylation levels of critical components of the MAPK signaling pathway, including ERK, JNK and P38, are dramatically decreased in VI-14-treated MDA-MB-231 cells. Furthermore, treatment of VI-14 significantly decreases the nuclear levels and the binding ability of nuclear factor-kappa B (NF-κB) and activator protein-1 (AP-1). Taken together, our data suggest that VI-14 treatment suppresses migration and motility of breast cancer cells, and VI-14 may be a potential compound for cancer therapy.     

Acetaminophen-induced differentiation of human breast cancer stem cells and inhibition of tumor xenograft growth in mice

It is now believed that cancer stem cells (CSCs) that are resistant to chemotherapy due to their undifferentiated nature drive tumor growth, metastasis and relapse, so development of drugs that induce differentiation of CSCs should have a profound impact on cancer eradication. In this study, we screened medicines that are already in clinical use for drugs that induce differentiation of CSCs. We used MDA-MB-231, a human breast cancer cell line that contains cancer stem cell-like cells. We found that acetaminophen, an anti-inflammatory, antipyretic and analgesic drug, induces differentiation of MDA-MB-231 cells. Differentiation was assessed by observing alterations in cell shape and expression of differentiated and undifferentiated cell markers, a decrease in cell invasion activity and an increase in susceptibility to anti-tumor drugs. This increased susceptibility seems to involve suppression of expression of multidrug efflux pumps. We also suggest that this induction of differentiation is mediated by inhibition of a Wnt/β-catenin canonical signaling pathway. Treatment of MDA-MB-231 cells with acetaminophen in vitro resulted in the loss of their tumorigenic ability in nude mice. Furthermore, administration of acetaminophen inhibited the growth of tumor xenografts of MDA-MB-231 cells in both the presence and absence of simultaneous administration of doxorubicine, a typical anti-tumor drug for breast cancer. Analysis with various acetaminophen derivatives revealed that o-acetamidophenol has a similar differentiation-inducing activity and a similar inhibitory effect on tumor xenograft growth. These results suggest that acetaminophen may be beneficial for breast cancer chemotherapy by inducing the differentiation of CSCs.     

Hexachlorobenzene induces cell proliferation and IGF-I signaling pathway in an estrogen receptor α-dependent manner in MCF-7 breast cancer cell line

Hexachlorobenzene (HCB) is an organochlorine pesticide widely distributed in the biosphere. ERα regulates the expression of genes involved in growth and development, and plays an important role in breast cancer. The present study focuses attention on the effect of HCB (0.005, 0.05, 0.5, 5 μM) on cell proliferation in estrogen receptor α (ERα)(+) MCF-7, and ERα(−) MDA-MB-231 breast cancer cell lines. We also studied the insulin growth factor-I (IGF-I) signaling pathway in MCF-7 cells. HCB (0.005 and 0.05 μM) stimulated cell proliferation in MCF-7, but not in MDA-MB-231 cells. The pesticide increased apoptosis in MCF-7, at HCB (0.5 and 5 μM). At these doses, HCB induced the expression of the aryl hydrocarbon receptor (AhR)-regulated gene cytochrome P4501A1. MCF-7 cells exposed to HCB (0.005 and 0.05 μM) overexpressed IGF-IR and insulin receptor (IR). IRS-1-phosphotyrosine content was increased in a dose dependent manner. ICI 182,780 prevented HCB-induced cell proliferation and IGF-I signaling in MCF-7 cells incubated in phenol-red free media. In addition, HCB (0.005 μM) increased c-Src activation, Tyr537-ERα phosphorylation and ERα down-regulation. Taken together, our data indicate that HCB stimulation of cell proliferation and IGF-I signaling is ERα dependent in MCF-7 cells.     

The role of cyclooxygenase-2-dependent signaling via cyclic AMP response element activation on aromatase up-regulation by o,p′-DDT in human breast cancer cells

o,p′-Dichlorodiphenyltrichloroethane (o,p′-DDT) is a DDT isomer and xenoestrogen that can induce inflammation and cancer. However, the effect of o,p′-DDT on aromatase is unclear. Thus, we investigated the effects of o,p′-DDT on aromatase expression in human breast cancer cells. We also examined whether cyclooxygenase-2 (COX-2) is involved in o,p′-DDT-mediated aromatase expression. Treatment with o,p′-DDT-induced aromatase protein expression in MCF-7 and MDA-MB-231 human breast cancer cells; enhancing aromatase gene expression, and enzyme and promoter activity. Treatment with ICI 182.780, a estrogen receptor antagonist, did not affect the inductive effects of o,p′-DDT on aromatase expression. In addition, o,p′-DDT increased COX-2 protein levels markedly, increased COX-2 mRNA expression and promoter activity, enhanced the production of prostaglandin E₂ (PGE₂), induced cyclic AMP response element (CRE) activation, and cAMP levels and binding of CREB. o,p′-DDT also increased the phosphorylation of PKA, Akt, ERK, and JNK in their signaling pathways in MCF-7 and MDA-MB-231 cells. Finally, o,p′-DDT induction of aromatase was inhibited by various inhibitors [COX-2 (by NS-398), PKA (H-89), PI3-K/Akt (LY 294002), EP2 (AH6809), and EP4 receptor (AH23848)]. Together, these results suggest that o,p′-DDT increases aromatase, and that o,p′-DDT-induced aromatase is correlated with COX-2 up-regulation, mediated via the CRE activation and PKA and PI3-kinase/Akt signaling pathways in breast cancer cells.