紫杉醇诱导MCF-7乳腺癌细胞凋亡的蛋白质组研究

目的 研究紫杉醇诱导MCF-7乳腺癌细胞凋亡的分子机制。方法 以100nmol／L紫杉醇作用MCF-7细胞24h后提取细胞总蛋白,利用蛋白质组技术,对紫杉醇诱导的MCF-7乳腺癌细胞凋亡前后的细胞蛋白进行二维电泳图谱分析,通过质谱鉴定差异蛋白质。结果 通过对凋亡前后的蛋白质组二维电泳图谱分析,找到了17个差异较大的蛋白质,其中6个蛋白质通过质谱得到了鉴定,它们是烯醇化酶、细胞核氯离子通道蛋白、角蛋白8、核糖体蛋白S12、galectin-1和Hint。结论 通过蛋白质组技术,发现了在紫杉醇诱导MCF-7乳腺癌细胞凋亡前后发生变化的6种蛋白质;这些差异蛋白质在紫杉醇诱导细胞凋亡中发挥一定的作用。     

蝙蝠葛碱在人乳腺癌MCF-7细胞对5氟尿嘧啶敏感性的研究

目的 探讨人乳腺癌MCF-7细胞受蝙蝠葛碱(Dauricine,Dau)作用后,对5氟尿嘧啶(5-FU)敏感性的影响。方法 分别以终浓度为2.5 μg/mL的蝙蝠葛碱、50 μg/mL的5-FU、2.5 μg/mL的蝙蝠葛碱和50 μg/mL的5-FU作用于人乳腺癌细胞MCF-7,运用MTT法检测细胞增殖活性,Transwell实验分析细胞的迁移,DAPI染色检测细胞的凋亡,Western blot法检测cyclinD1和Bcl-2蛋白的表达。结果 MTT实验结果显示联合使用阈下浓度的蝙蝠葛碱增强了5-FU对细胞增殖的抑制;Transwell实验表明联合应用阈下浓度的蝙蝠葛碱进一步加剧了5-FU对细胞迁移的抑制;DAPI染色说明联合应用阈下剂量的蝙蝠葛碱加强了5-FU对细胞凋亡的诱导,Western blot实验表明联合应用阈下浓度的蝙蝠葛碱进一步抑制了cyclinD1和Bcl-2蛋白的表达。结论 蝙蝠葛碱可有效增强人乳腺癌MCF-7细胞对5-FU的敏感性。     

RhG-CSF对乳腺癌细胞MCF-7增殖作用的影响

目的：探讨人重组粒细胞集落刺激因子（RhG-CSF）对乳腺癌细胞株MCF-7的增殖作用的影响。方法：体外培养人乳腺癌细胞株MCF-7,将含不同浓度RhG-CSF的培养液与MCF-7细胞共同培养不同时间,采用MTT比色法计算细胞生长增殖率;Anexxin V/PI双染试剂盒检测细胞凋亡率。实验结果用SPSS.v16.0软件分析。结果：不同浓度RhG-CSF处理细胞后,可以显著促进MCF-7细胞株的增殖（P〈0.01）,且当浓度为10μg/L时增殖作用最强。同时各浓度的RhG-CSF亦可抑制MCF-7细胞凋亡（P〈0.01）。结论：RhG-CSF可以显著促进人乳腺癌细胞株MCF-7增殖。当浓度小于10μg/L时,增殖呈浓度依赖性。大于10μg/L时,增殖能力反而逐渐下降。同时RhG-CSF亦可抑制MCF-7细胞凋亡。     

RhG-CSF对乳腺癌细胞MCF-7增殖作用的影响

目的:探讨人重组粒细胞集落刺激因子(RhG-CSF)对乳腺癌细胞株MCF-7的增殖作用的影响。方法:体外培养人乳腺癌细胞株MCF-7,将含不同浓度RhG-CSF的培养液与MCF-7细胞共同培养不同时间,采用MTT比色法计算细胞生长增殖率;Anexxin V/PI双染试剂盒检测细胞凋亡率。实验结果用SPSS.v16.0软件分析。结果:不同浓度RhG-CSF处理细胞后,可以显著促进MCF-7细胞株的增殖(P<0.01),且当浓度为10μg/L时增殖作用最强。同时各浓度的RhG-CSF亦可抑制MCF-7细胞凋亡(P<0.01)。结论:RhG-CSF可以显著促进人乳腺癌细胞株MCF-7增殖。当浓度小于10μg/L时,增殖呈浓度依赖性。大于10μg/L时,增殖能力反而逐渐下降。同时RhG-CSF亦可抑制MCF-7细胞凋亡。     

Gold nanoparticles induce apoptosis in MCF-7 human breast cancer cells

Background: Gold nanoparticles have recently been investigated with respect to biocompatibility accordingto their interactions with cells. The purpose of this study was to examine cytotoxicity and apoptosis induction bywell-characterized gold nanoparticles in human breast epithelial MCF-7 cells. Methods: Apoptosis was assessedby TUNEL, cytotoxicity by MTT assay and caspase 3, 9, p53, Bax and Bcl expression by real-time PCR assays.Results: Gold nanoparticles at up to 200 μg/mL for 24 hours exerted concentration-dependent cytotoxicity andsignificant upregulation of mRNA expression of p53, bax, caspase-3 & caspase-9, whereas expression of antiapoptoticbcl-2 was down-regulated. Conclusion: To the best of our knowledge this is the first report showingthat gold nanoparticles induce apoptosis in MCF-7cells via p53, bax/bcl-2 and caspase pathways.     

Modulation of 5-FU metabolism in human MCF-7 breast carcinoma cells

Summary We have previously demonstrated a highly significant relationship (P<0.0001) between the incorporation of 5-fluorouracil (5-FU) into total cellular RNA and loss of clonogenic survival of the human MCF-7 breast carcinoma cell line. The present studies explore the applicability of this relationship to MCF-7 cells exposed to 5-FU and modulting agents such as PALA, MTX, and MMPR. PALA treatment produces a minimal increase in the absolute amount of 5-FU incorporated into total cellular RNA, but it results in a three-fold enhancement of the [³H]FU/³²P ratio, which measures 5-FU misincorporation into newly synthesized RNA. MTX and MMPR increase intracellular PRPP levels up to four-fold; nevertheless these agents result in only minimal increases in absolute (5-FU) RNA formation. In contrast, the relative incorporation of 5-FU into newly synthesized RNA of MTX-or MMPR-treated cells is increased 2.5-fold. The combination of PALA/MMPR results in a two-fold absolute increase in (5-FU) RNA formation and a nine-fold enhancement of the [³H]FU/³²P ratio. Combinations of modulating agents with 5-FU result in more than additive decreases in MCF-7 clonogenic survival. The relationship between 5-FU incorporation into RNA and loss of clonogenic survival was highly significant (P<0.0002) when corrected for newly synthesized RNA, while the correlation with absolute amounts of (5-FU) RNA formation was less significant (P<0.05). These studies demonstrate that the relationship previously established between (5-FU)RNA formation and loss of clonogenic survival should be corrected for the amount of newly synthesized RNA when 5-FU is combined with modulating agents that alter rates of RNA synthesis.     

Biosynthesis of alpha fetoprotein by MCF-7 human breast cancer cells

Direct evidence was obtained for de novo synthesis of AFP by MCF-7 human breast cancer cells per se. Synthesis was demonstrated by L-14C-leucine and L-35S-methionine incorporation into immunochemically isolated AFP, and confirmed by radioimmunodiffusion and radioimmunoelectrophoresis. This information indicates that AFP synthesis is associated with normal and neoplastic cells of several different histotypes, and suggests that AFP detected and measured previously in primary human breast cancer tissue cytosol (Sarcione et al., 1983) also resulted from in situ biosynthesis by breast cancer cells per se rather than uptake of exogenous AFP originating from extracellular sources. Evidence that AFP obtained after treatment of 14C-leucine radiolabelled MCF-7 breast cancer cell protein with 0.4 M KCl contained 2.6 times more radioactivity than did AFP obtained before such salt treatment is interpreted as indicating that two different molecular species of de novo synthesized AFP existed in breast cancer cells: (1) larger amount of non-immunoreactive AFP which became immunoreactive and measurable after KCl treatment, and (2) smaller amounts of free immunoreactive AFP. 14C-radiolabelled AFP obtained before and after treatment of cell protein with 0.4 M KCl codiffused, comigrated with alpha 1 electrophoretic mobility and gave an identical radioimmunologic reaction both with each other and with added carrier human cord serum AFP. Furthermore, preliminary studies indicated that radiolabelled non-immunoreactive AFP could be separated from lower-molecular-weight free AFP by chromatography on Sephadex G-200. Taken together, these findings suggest that synthesized free AFP was bound as a non-immunoreactive high-molecular-weight macromolecular complex rather than being covalently linked. Our current working hypothesis is that most of the de novo synthesized endogenous AFP in MCF-7 human breast cancer cells was rapidly and reversibly bound by hydrophobic bonding to a specific cytoplasmic AFP-receptor.     

Proteomic analysis of differentially expressed proteins in hepatitis B virus-related hepatocellular carcinoma tissues

Background

Hepatocellular carcinoma (HCC), a major cause of cancer death in China, is preceded by chronic hepatitis and liver cirrhosis (LC). Although hepatitis B virus (HBV) has been regarded as a clear etiology of human hepatocarcinogenesis, the mechanism is still needs to be further clarified. In this study, we used a proteomic approach to identify the differential expression protein profiles between HCC and the adjacent non-tumorous liver tissues.

Methods

Eighteen cases of HBV-related HCC including 12 cases of LC-developed HCC and 6 cases of chronic hepatitis B (CHB)-developed HCC were analyzed by two-dimensional electrophoresis (2-DE) combined with matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), and the results were compared to those of paired adjacent non-tumorous liver tissues.

Results

A total of 17 differentially expressed proteins with diverse biological functions were identified. Among these, 10 proteins were up-regulated, whereas the other 7 proteins were down-regulated in cancerous tissues. Two proteins, c-Jun N-terminal kinase 2 and ADP/ATP carrier protein were found to be up-regulated only in CHB-developed HCC tissues. Insulin-like growth factor binding protein 2 and Rho-GTPase-activating protein 4 were down-regulated in LC-developed and CHB-developed HCC tissues, respectively. Although 11 out of these 17 proteins have been already described by previous studies, or are already known to be involved in hepatocarcinogenesis, this study revealed 6 new proteins differentially expressed in HBV-related HCC.

Conclusion

These findings elucidate that there are common features between CHB-developed HCC and LC-developed HCC. The identified proteins are valuable for studying the hepatocarcinogenesis, and may be potential diagnostic markers or therapeutic targets for HBV-related HCC.     

人乳腺癌MCF-7细胞中SP亚群细胞的分离及其生物学行为研究

目的:了解肿瘤干细胞的生物学行为及相关的调控机制.方法:采用干细胞对Hoechst33342染料外排的特性进行MCF-7 细胞系肿瘤干细胞的流式分选.并对其增殖、自我更新、分化能力等生物学行为进行研究.还利用流式细胞仪、免疫荧光技术、荧光定量PCR等技术进行了与干细胞生物学行为密切相关的Wnt信号转导通路中相关分子的表达特征研究.结果:MCF-7细胞系中包含SP亚群(side population);且SP细胞具有分化潜能,高增殖能力,及自我更新特性;而且Wnt通路的各种关键分子在该细胞系SP亚群细胞中呈活化状态.结论:MCF-7细胞系的SP亚群可以代表该细胞系的肿瘤干细胞,Wnt通路在该肿瘤细胞系肿瘤干细胞的自我更新等其它生物学行为的调控中起重要作用.     

TrkA-siRNA增强人乳腺癌MCF-7细胞对紫杉醇的敏感性

目的 探讨靶向抑制TrkA基因表达后,人乳腺癌细胞MCF-7对化疗药物紫杉醇敏感性的变化.方法 8 μmol/L紫杉醇作用于乳腺癌MCF-7亲本细胞株和TrkA-siRNA转染细胞株24、48小时后,MTT法检测细胞增殖抑制效应,Western blot检测凋亡蛋白caspase-3的活化.倒置显微镜观察细胞株生长的形态学变化.结果 紫杉醇作用24、48小时后,其对TrkA-siRNA细胞株的生长抑制均高于MCF-7亲本细胞株(P＜0.05),且48小时抑制率高于24小时(P＜0.05).Western blot结果显示,caspase-3蛋白在紫杉醇作用24小时后被激活,其在TrkA-siRNA细胞株中的表达高于MCF-7亲本细胞株(P＜0.05).结论 TrkA-siRNA能增加乳腺癌细胞对化疗药物紫杉醇的敏感性.     

Proteomic profiling of MCF-7 breast cancer cells with chemoresistance to different types of anti-cancer drugs

Chemoresistance is a poor prognostic factor in breast cancer and, thus, presents a significant clinical challenge. The mechanisms of chemoresistance involve multiple complex biological processes. This study aims to identify common contributory factors to chemoresistance in breast cancer by comparing protein expression profiles of chemosensitive MCF-7 breast cancer cells and cells resistant to two different commonly used anti-cancer drugs (adriamycin and paclitaxel). Expression of the ATP binding cassette transporter, P-glycoprotein (P-gp), in breast tumours has previously been found to correlate with poor prognosis in vivo and, accordingly, we confirmed overexpression of P-gp in both adriamycin- and paclitaxel-resistant MCF-7 cells. Using two-dimensional gel electrophoresis and MALDI-TOF peptide mass fingerprinting, we identified 20 proteins differentially expressed between chemosensitive, adriamycin-resistant and paclitaxel-resistant MCF-7 cells. Cytokeratin-8, keratin-19, Hsp-27, 14-3-3 epsilon, annexin-A2 and phosphoglycerate kinase-1 showed altered expression in both adriamycin- and paclitaxel-resistant cells. Validation of a number of these changes was confirmed by Western blotting. Our findings provide further insights into the complex mechanisms of chemoresistance, as well as representing an attractive starting point for the identification of potential protein biomarkers to predict response to chemotherapy in breast cancer in vivo.     

Paradoxical regulation of Bcl-2 family proteins by 17beta-oestradiol in human breast cancer cells MCF-7.

Tumorigenesis is related to the dysregulation of cell growth or cell death pathways. Hence, elucidation of the mechanisms involved in the modulation of pro- or anti-apoptotic proteins is important in furthering understanding of breast cancer aetiology and may aid in designing prevention and treatment strategies. In the present study, we examined the role of 17beta-oestradiol on the regulation of apoptosis in the breast cancer cell line MCF-7. Using multi-probe RNAase protection assays, we found changes in the mRNA levels of several Bcl-2 family proteins upon treatment of MCF-7 cells with 17beta-oestradiol. Unexpectedly, we found a paradoxical effects of 17beta-oestradiol on two anti-apoptotic proteins Bcl-2 and Bcl-x. Treatment with 17beta-oestradiol resulted in up-regulation of Bcl-2 mRNA and protein, but down-regulated Bcl-x(L) mRNA and protein. The effect of 17beta-oestradiol on Bcl-x(L) occurred at concentration-dependent fashion. The effect was specific to 17beta-oestradiol since other steroid hormones exert no effect on Bcl-x(L). Tamoxifen, an anti-oestrogen, blocked the down-regulation of Bcl-x(L) by 17beta-oestradiol demonstrating this effect is oestrogen receptor-dependent. We speculate that different members of the Bcl-2 family proteins may be regulated through different pathway and these pathways may be modulated by 17beta-oestradiol.     

Identification of differentially expressed microRNAs in human male breast cancer

Background  

The discovery of small non-coding RNAs and the subsequent analysis of microRNA expression patterns in human cancer specimens have provided completely new insights into cancer biology. Genetic and epigenetic data indicate oncogenic or tumor suppressor function of these pleiotropic regulators. Therefore, many studies analyzed the expression and function of microRNA in human breast cancer, the most frequent malignancy in females. However, nothing is known so far about microRNA expression in male breast cancer, accounting for approximately 1% of all breast cancer cases.     

Antitumor activity of colloidal silver on MCF-7 human breast cancer cells

Background

Colloidal silver has been used as an antimicrobial and disinfectant agent. However, there is scarce information on its antitumor potential. The aim of this study was to determine if colloidal silver had cytotoxic effects on MCF-7 breast cancer cells and its mechanism of cell death.

Methods

MCF-7 breast cancer cells were treated with colloidal silver (ranged from 1.75 to 17.5 ng/mL) for 5 h at 37°C and 5% CO₂ atmosphere. Cell Viability was evaluated by trypan blue exclusion method and the mechanism of cell death through detection of mono-oligonucleosomes using an ELISA kit and TUNEL assay. The production of NO, LDH, and Gpx, SOD, CAT, and Total antioxidant activities were evaluated by colorimetric assays.

Results

Colloidal silver had dose-dependent cytotoxic effect in MCF-7 breast cancer cells through induction of apoptosis, shown an LD₅₀ (3.5 ng/mL) and LD₁₀₀ (14 ng/mL) (*P < 0.05), significantly decreased LDH (*P < 0.05) and significantly increased SOD (*P < 0.05) activities. However, the NO production, and Gpx, CAT, and Total antioxidant activities were not affected in MCF-7 breast cancer cells. PBMC were not altered by colloidal silver.

Conclusions

The present results showed that colloidal silver might be a potential alternative agent for human breast cancer therapy.     

Anti-apoptotic effect of claudin-1 in tamoxifen-treated human breast cancer MCF-7 cells

Background  

Claudin-1 is a membrane protein of tight junctions, and is associated with the development of various cancers. However, the significance of claudin-1 expression in cancer cells is not well understood. Here, we showed for the first time the anti-apoptotic effect of claudin-1 in human breast cancer MCF-7 cells.     

Proteasome-mediated degradation of BRCA1 protein in MCF-7 human breast cancer cells

The breast and ovarian cancer susceptibility gene BRCA1 encodes a nuclear phosphoprotein, which functions as a tumor suppressor gene. We present several lines of evidence for the mechanism of BRCA1 degradation through the ubiquitin-proteasome pathway by using specific inhibitors of the proteasome in human MCF-7 breast carcinoma cells. The levels of BRCA1 protein were up-regulated by proteasome inhibitors, such as MG-132 and ALLnL, suggesting rapid degradation via the ubiquitin-proteasome pathway. The enhanced loss of BRCA1 protein by taxol, okadaic acid or nocodazole treatment was prevented by the proteasome inhibitors, while inhibition of other proteases was ineffective. Accumulation and proteasomal degradation of BRCA1 protein appear to be restricted entirely to the nucleus. We also detected that high molecular weight BRCA1 protein species appeared after proteasome inhibitor treatments, which indicated that ubiquitinated species were present. Moreover the half-life of BRCA1 protein was significantly increased in response to inhibition of proteasome activity. Our present data demonstrate that BRCA1 protein may be degraded through the ubiquitin-proteasome mediated pathway.     

Antiestrogenic activities of alternate-substituted polychlorinated dibenzofurans in MCF-7 human breast cancer cells

Purpose: 1,3,6,8-Substituted alkyl polychlorinated dibenzofurans (PCDFs), typified by 6-methyl-1,3,8-triCDF (MCDF), inhibit 17β-estradiol (E2)-induced responses in the rodent uterus and human breast cancer cells. The major purpose of the experiments reported here was to determine the structure-dependent antiestrogenic activities of several alternate-substituted (1,3,6,8- and 2,4,6,8-) PCDFs. Methods: The antiestrogenic activities were determined in MCF-7 human breast cancer cells using two assays, that is E2-induced cell proliferation and induction of chloramphenicol acetyl transferase (CAT) activity in cells transiently transfected with the E2-responsive Vit-CAT plasmid. Results: MCDF (10⁻⁵ M ), 6-isopropyl-1,3,8-triCDF, 6-ethyl-1,3,8-triCDF, 3-isopropyl-6-methyl-1,8-diCDF, and 6-methyl-2,4,8-triCDF, inhibited both E2-induced cell proliferation and CAT activity in MCF-7 cells. All of the remaining ten congeners inhibited either E2-induced cell proliferation or CAT activity, but not both responses. Conclusions: The antiestrogenic activity of the alternate-substituted PCDFs involves interactions between the aryl hydrocarbon and estrogen receptor signaling pathways. Although these compounds exhibited antiestrogenic activity in MCF-7 cells, the effects of individual congeners were response-specific, and there were no apparent structure-activity relationships. Received: 26 July 1996 / Accepted: 16 November 1996     

Proteomics reveals protein profile changes in doxorubicin--treated MCF-7 human breast cancer cells

MCF-7 cells are extensively used as a cell model to investigate human breast tumors and the cellular mechanism of antitumor drugs such as doxorubicin (DOX), an anthracycline antitumor drug widely used in clinical chemotherapy. To understand the effects of DOX on the protein expression, we perform a comprehensive proteomics to survey global changes in proteins after DOX treatment in MCF-7 cells. Exposure of MCF-7 cells to 0.1 microM DOX for 2 days induced a differentiation-like phenotype with prominent perinuclear autocatalytic vacuoles, abundant filamentous material, and irregular microvilli at the cell surface. In this study, we also present a proteome reference map of MCF-7 cells with 21 identified protein spots via analysis of N-terminal sequencing, mass spectrometry, immunoblot and/or computer matching with protein database. Based on the proteome map, we found that DOX causes a markedly decrease in the levels of three isoforms of heat shock protein 27 (HSP27) whereas the levels of other stress associated proteins including HSP60, calreticulin, and protein disulfide isomerase were not significantly altered in DOX-treated MCF-7 cells. Taken together, we suggest that that action of DOX on breast tumor cells may be partly related to dysregulation of HSP27 expression. Modulation of HSP27 levels may be a clinically useful potential target for design of antitumor drugs and controlling breast tumor growth.     

Dehydroepiandrosterone and estrone 17-ketosteroid reductases in MCF-7 human breast cancer cells

Summary The identification of several steroid-transforming enzymes within human breast cancers has led to speculation that the growth of some hormone-responsive tumors might be mediated in part by intracellularly derived estrogens. Reports that MCF-7 human breast cancer cells can transform both estrone (E1)¹ to estradiol (E2) and dehydroepiandrosterone (DHEA) to the estrogenic steroid 5-androstenediol (AED), have prompted us to investigate the 17-ketosteroid reductase activities (17-KSR's) which mediate these potentially important reactions. Enzyme assays were performed by quantifying the amounts of [³H]AED or [³H]E2 former from [³H]DHEA or [³H]E1, respectively, by various subcellular preparations from MCF-7 cells under a variety of experimental conditions. DHEA 17-KSR was found to be localized exclusively within cytosol, whereas the E1 17-KSR activity appeared to be nearly equally divided between the soluble and particulate cytoplasmic subfractions. The particulate E1 17-KSR appeared capable of utilizing NADH or NADPH, whereas both the cytosolic form of this enzyme and the soluble DHEA 17-KSR activity showed a strict requirement for NADPH. Although both of the soluble 17-KSR's also showed similar pH optima, several other features suggested that they are different enzymes in MCF-7. E1 did not inhibit the conversion of DHEA to AED, and DHEA did not interfere with the transformation of E1 to E2, indicating that major differences in substrate specificity exist between the two cytosolic activities. Furthermore, DHEA 17-KSR activity within cytosol stored at –20°C deteriorated almost completely over twelve weeks of storage, whereas E1 17-KSR activity remained stable. Finally, although both enzymes were found to be subject to product inhibition, AED inhibited DHEA 17-KSR competitively, whereas cytosolic E1 17-KSR activity was inhibited by E2 in noncompetitive fashion. Studies of the oxidation of E2 to E1 by MCF-7 cells showed that this transformation is catalyzed by both soluble and particulate 17-hydroxysteroid oxidases which utilize either NAD or NADP as cofactor. Having previously reported the presence of a particulate NADP(H)-linked androstenedione (AE) 17-ketosteroid oxidoreductase in MCF-7, we now suggest that at least three different enzymes, one particulate and two soluble forms, participate in the conversion of 17-ketosteroids to their hormonally active 17-hydroxysteroid derivatives within this cell line. The restricted substrate requirements of each enzyme provide a rationale for developing selective enzyme inhibitors which could provide important investigational tools and potentially effective therapeutic agents.Abbreviations E2 estradiol, 1,3,5(10)-estratrien-3, 17-diol - E2Me Estradiol 3-methyl ether - E1 estrone, 1,3,5(10)-estratrien-3-ol-17-one - E1Me estrone 3-methyl ether - E1S estrone sulfate - DHEA dehydroepiandrosterone, 5-androsten-3-ol-17-one - DHEAS Dehydroepiandrosterone sulfate - AED androstenediol, 5-androsten-3, 17-diol - AE androstenedione, 4-androsten-3,17-dione - T testosterone, 4-androsten-17-ol-3-one