5′-AMP-activated Protein Kinase (AMPK) Supports the Growth of Aggressive Experimental Human Breast Cancer Tumors

Rapid tumor growth can establish metabolically stressed microenvironments that activate 5′-AMP-activated protein kinase (AMPK), a ubiquitous regulator of ATP homeostasis. Previously, we investigated the importance of AMPK for the growth of experimental tumors prepared from HRAS-transformed mouse embryo fibroblasts and for primary brain tumor development in a rat model of neurocarcinogenesis. Here, we used triple-negative human breast cancer cells in which AMPK activity had been knocked down to investigate the contribution of AMPK to experimental tumor growth and core glucose metabolism. We found that AMPK supports the growth of fast-growing orthotopic tumors prepared from MDA-MB-231 and DU4475 breast cancer cells but had no effect on the proliferation or survival of these cells in culture. We used in vitro and in vivo metabolic profiling with [¹³C]glucose tracers to investigate the contribution of AMPK to core glucose metabolism in MDA-MB-231 cells, which have a Warburg metabolic phenotype; these experiments indicated that AMPK supports tumor glucose metabolism in part through positive regulation of glycolysis and the nonoxidative pentose phosphate cycle. We also found that AMPK activity in the MDA-MB-231 tumors could systemically perturb glucose homeostasis in sensitive normal tissues (liver and pancreas). Overall, our findings suggest that the contribution of AMPK to the growth of aggressive experimental tumors has a critical microenvironmental component that involves specific regulation of core glucose metabolism.     

乳腺癌细胞中人血小板衍生生长因子受体β启动子的基础活性研究

目的:探讨低迁移表型的乳腺癌细胞MCF-7和高迁移表型的乳腺癌细胞MDA-MB-231中血小板衍生生长因子β启动子的基础活性及转录调控差异。方法:Real-Time PCR,Weastern blot等技术检测PDGFRβ在2株细胞中的转录和表达差异。双荧光报告系统检测PDGFRβ启动子各缺失突变片段在2株细胞中的活性,筛选差异片段。生物信息学预测启动子区可能存在的转录因子。凝胶迁移实验研究转录因子在两株乳腺癌细胞中对PDGFRβ启动子的调节活性。结果:两株细胞中都有PDGFRβ的内源性表达,且在MDA-MB-231中表达较高。在2株细胞中找到了人PDGFRB 启动子的重要活性调节区,(+539bp,+1457bp)在2株细胞中均呈负调控,(+54bp,+539bp)在两株细胞中均呈正调控,(-983bp,+54bp)在MDA-MB-231中呈显著正调控,在MCF-7中没有活性。转录因子AP1的转录活性和与DNA的结合活性在MDA-MB-231中均高于MCF-7。结论:不同迁移表型的乳腺癌细胞中PDGFRβ存在不同的表达调控机制,PDGFRβ启动子活性片段(-983bp,+54bp)在两株细胞中存在显著活性差异。转录因子AP-1在两株细胞中有表达水平和结合活性差异。     

Molecular Modification of Metadherin/MTDH Impacts the Sensitivity of Breast Cancer to Doxorubicin

BackgroundBreast cancer is a leading cause of death in women and with an increasing worldwide incidence. Doxorubicin, as a first-line anthracycline-based drug is conventional used on breast cancer clinical chemotherapy. However, the drug resistances limited the curative effect of the doxorubicin therapy in breast cancer patients, but the molecular mechanism determinants of breast cancer resistance to doxorubicin chemotherapy are not fully understood. In order to explore the association between metadherin (MTDH) and doxorubicin sensitivity, the differential expressions of MTDH in breast cancer cell lines and the sensitivity to doxorubicin of breast cancer cell lines were investigated.MethodsThe mRNA and protein expression of MTDH were determined by real-time PCR and Western blot in breast cancer cells such as MDA-MB-231, MCF-7, MDA-MB-435S, MCF-7/ADR cells. Once MTDH gene was knocked down by siRNA in MCF-7/ADR cells and overexpressed by MTDH plasmid transfection in MDA-MB-231 cells, the cell growth and therapeutic sensitivity of doxorubicin were evaluated using MTT and the Cell cycle assay and apoptosis rate was determined by flow cytometry.ResultsMCF-7/ADR cells revealed highly expressed MTDH and MDA-MB-231 cells had the lowest expression of MTDH. After MTDH gene was knocked down, the cell proliferation was inhibited, and the inhibitory rate of cell growth and apoptosis rate were enhanced, and the cell cycle arrest during the G0/G1 phase in the presence of doxorubicin treatment. On the other hand, the opposite results were observed in MDA-MB-231 cells with overexpressed MTDH gene.ConclusionMTDH gene plays a promoting role in the proliferation of breast cancer cells and its high expression may be associated with doxorubicin sensitivity of breast cancer.     

Galectin-3 as a Marker and Potential Therapeutic Target in Breast Cancer

Galectin-3 has a relatively high level of expression in triple-negative breast cancers and is a potential marker for this disease. However, the clinical and prognostic implications of galectin-3 expression in breast cancer remain unclear. We examined mastectomy specimens from 1086 breast cancer cases and matching, adjacent non-cancerous tissues using immunohistochemistry. Overall, triple-negative breast cancers expressed galectin-3 more strongly than did other breast cancers types (63.59% vs 21.36%, P = 0.001). Galectin-3 expression was not found to be an independent prognostic factor for breast cancer by Cox regression analysis, but was associated with chemotherapeutic resistance. Apoptosis was only weakly induced by arsenic trioxide (ATO) treatment in galectin-3-positive breast cancer cells (MDA-MB-231 and MCF-7), although ATO treatment up-regulated galectin-3 expression. Knockdown of galectin-3 in MDA-MB-231 cells sensitized them to killing by ATO. These findings support a possible role for galectin-3 as a marker for triple-negative breast cancer progression and as a therapeutic target in combination with ATO treatment, although the mechanisms that underlie this synergy require further investigation.     

Numb在三阴乳腺癌中抑制HDM2泛素化降解p53

目的:探究Numb蛋白在三阴乳腺癌患者中的表达降低情况,及Numb蛋白在三阴乳腺癌中对抑癌因子p53蛋白水平的影响及调控机制,进一步研究Numb蛋白的降低与三阴乳腺癌发生发展的相关性,从而为缺乏有效治疗方法的三阴乳腺癌提供一个潜在的治疗新靶点。方法:40例三阴乳腺癌患者病理组织切片取自重庆医科大学临床病理诊断中心,采用免疫组化法检测Numb蛋白在三阴乳腺癌患者中的表达情况。MCF-10A细胞株和MDA-MB-231细胞株均为ATCC来源,采用qPCR和Western blot法检测对比Numb、HDM2、p53三者的转录水平和蛋白质水平在以上两个细胞株中差异。采用增强型绿色荧光蛋白(enhance green fluorescent protein,EGFP)质粒转染的方法在MDA-MB-231细胞中重表达Numb,采用q PCR和Western blot法验证Numb、HDM2、p53三者表达的变化。结果:转染NUMB-EGFP后MDA-MB-231细胞中Numb的mRNA和蛋白质水平均明显上调,HDM2无显著改变,p53在转录水平无明显变化,但在蛋白质水平显著升高。在231细胞中上调Numb蛋白可以在转录后水平调节p53水平,使p53蛋白随之显著升高。结论:Numb蛋白在三阴乳腺癌患者中表达降低的比列很高,为55%,且Numb蛋白在三阴乳腺癌细胞MDA-MB-231中可以调控抑癌因子p53蛋白水平,Numb蛋白水平与p53蛋白水平呈正相关。     

Different effects of genistein on molecular markers related to apoptosis in two phenotypically dissimilar breast cancer cell lines

The association between consumption of genistein-containing soybean products and lower risk of breast cancer suggests a cancer chemopreventive role for genistein. Consistent with this suggestion, exposing cultured human breast cancer cells to genistein inhibits cell proliferation, although this is not completely understood. To better understand how genistein works, the ability of genistein to induce apoptosis was compared in phenotypically dissimilar MCF-7 and MDA-MB-231 human breast cancer cells that express the wild-type and mutant p53 gene, respectively. After 6 days of incubation with 50 microM genistein, MCF-7 but not MDA-MB-231 cells, showed morphological signs of apoptosis. Marginal proteolytic cleavage of poly-(ADP-ribose)-polymerase and significant DNA fragmentation were also detected in MCF-7 cells. In elucidating these findings, it was determined that after 2 days of incubation with genistein, MCF-7 but not MDA-MB-231 cells, had significantly higher levels of p53. Accordingly, the expression of certain proteins modulated by p53 was studied next. Levels of p21 increased in both of the genistein-treated cell lines, suggesting that p21 gene expression was activated but in a p53-independent manner, whereas no significant changes in levels of the pro-apoptotic protein, Bax, were found. In MCF-7 cells, levels of the anti-apoptotic protein, Bcl-2, decreased slightly at 18-24 h but then increased considerably after 48 h. Hence, the Bax:Bcl-2 ratio initially increased but later decreased. These data suggest that at the genistein concentration tested, MCF-7 cells in contrast to MDA-MB-231 cells were sensitive to the induction of apoptosis by genistein, but Bax and Bcl-2 did not play clear roles.     

Different anticancer effects of Saxifragifolin A on estrogen receptor-positive and estrogen receptor-negative breast cancer cells

BackgroundBreast cancer is the leading cause of cancer-related death among women worldwide. For treating breast cancer, numerous natural products have been considered as chemotherapeutic drugs.Hypothesis/purposeThe present study aims to investigate the apoptotic effect of Saxifragifolin A (Saxi A) isolated from Androsace umbellata in two different human breast cancer cells which are ER-positive MCF-7 cells and ER-negative MDA-MB-231 cells, and examine the molecular basis for its anticancer actions.Study designThe inhibitory effects of Saxi A on cell survival were examined in MCF-7 cells and MDA-MB-231 cells in vitro.MethodsMTT assays, Annexin V/PI staining analysis, ROS production assay, Hoechst33342 staining and Western blot analysis were performed.ResultsOur results showed that MDA-MB-231 cells were more sensitive to Saxi A-induced apoptosis than MCF-7 cells. Saxi A induced apoptosis in MDA-MB-231 cells through ROS-mediated and caspase-dependent pathways, whereas treatment with Saxi A induced apoptosis in MCF-7 cells in a caspase-independent manner. In spite of Saxi A-induced activation of MAPKs in both breast cancer cell lines, only p38 MAPK and JNK mediated Saxi A-induced apoptosis. In addition, cell survival of shERα-transfected MCF-7 cells was decreased, while MDA-MB-231 cells that overexpress ERα remained viable.ConclusionSaxi A inhibits cell survival in MCF-7 cells and MDA-MB-231 cells through different regulatory pathway, and ERα status appears to be important for regulating Saxi A-induced apoptosis in breast cancer cells. Thus, Saxi A may have a potential therapeutic use for treating breast cancer.     

IL-7 splicing variant IL-7δ5 induces human breast cancer cell proliferation via activation of PI3K/Akt pathway

Various tumor cells express interleukin 7 (IL-7) and IL-7 variants. IL-7 has been confirmed to stimulate solid tumor cell proliferation. However, the effect of IL-7 variants on tumor cell proliferation remains unclear. In this study, we evaluated the role of IL-7δ5 (an IL-7 variant lacking exon 5) on proliferation and cell cycle progression of human MDA-MB-231 and MCF-7 breast cancer cells. The results showed that IL-7δ5 promoted cell proliferation and cell cycle progression from G1 phase to G2/M phase, associated with upregulation of cyclin D1 expression and the downregulation of p27(kip1) expression. Mechanistically, we found that IL-7δ5 induced the activation of Akt. Inhibition of PI3K/Akt pathway by LY294002 reversed the proliferation and cell cycle progression of MDA-MB-231 and MCF-7 cells induced by IL-7δ5. In conclusion, our findings demonstrate that IL-7δ5 variant induces human breast cancer cell proliferation and cell cycle progression via activation of PI3K/Akt pathway. Thus, IL-7δ5 may be a potential target for human breast cancer therapeutics intervention.     

MicroRNA-3646 Contributes to Docetaxel Resistance in Human Breast Cancer Cells by GSK-3β/β-Catenin Signaling Pathway

Acquisition of resistance to docetaxel (Doc) is one of the most important problems in treatment of breast cancer patients, but the underlying mechanisms are still not fully understood. In present study, Doc-resistant MDA-MB-231 and MCF-7 breast cancer cell lines (MDA-MB-231/Doc and MCF-7/Doc) were successfully established in vitro by gradually increasing Doc concentration on the basis of parental MDA-MB-231 and MCF-7 cell lines (MDA-MB-231/S and MCF-7/S). The potential miRNAs relevant to the Doc resistance were screened by miRNA microarray. We selected 5 upregulated miRNAs (has-miR-3646, has-miR-3658, has-miR-4438, has-miR-1246, and has-miR-574-3p) from the results of microarray for RT-qPCR validation. The results showed that expression level of miR-3646 in MDA-MB-231/Doc cells was significantly higher than in MDA-MB-231/S cells. Compared to MCF-7/S cells, miR-3646 expression was up-regulated in MCF-7/Doc cells. Further studies revealed that transfection of miR-3646 mimics into MDA-MB-231/S or MCF-7/S cells remarkably increased their drug resistance, in contrast, transfection of miR-3646 inhibitors into MDA-MB-231/Doc or MCF-7/Doc cells resulted in significant reduction of the drug resistance. By the pathway enrichment analyses for miR-3646, we found that GSK-3β/β-catenin signaling pathway was a significant pathway, in which GSK-3β was an essential member. RT-qPCR and Western blot results demonstrated that miR-3646 could regulate GSK-3β mRNA and protein expressions. Furthermore, a marked increase of both nuclear and cytoplasmic β-catenin expressions (with phosphorylated-β-catenin decrease) was observed in MDA-MB-231/Doc cells compared with MDA-MB-231/S cells, and their expression were positively related to miR-3646 and negatively correlated with GSK-3β. Taken together, our results suggest that miR-3646-mediated Doc resistance of breast cancer cells maybe, at least in part, through suppressing expression of GSK-3β and resultantly activating GSK-3β/β-catenin signaling pathway.     

MiR-487a Promotes TGF-β1-induced EMT,the Migration and Invasion of Breast Cancer Cells by Directly Targeting MAGI2

Tumor metastasis is a complex and multistep process and its exact molecular mechanisms remain unclear. We attempted to find novel microRNAs (miRNAs) contributing to the migration and invasion of breast cancer cells. In this study, we found that the expression of miR-487a was higher in MDA-MB-231breast cancer cells with high metastasis ability than MCF-7 breast cancer cells with low metastasis ability and the treatment with transforming growth factor β1 (TGF-β1) significantly increased the expression of miR-487a in MCF-7 and MDA-MB-231 breast cancer cells. Subsequently, we found that the transfection of miR-487a inhibitor significantly decreased the expression of vimentin, a mesenchymal marker, while increased the expression of E-cadherin, an epithelial marker, in both MCF-7 cells and MDA-MB-231 cells. Also, the inactivation of miR-487a inhibited the migration and invasion of breast cancer cells. Furthermore, our findings demonstrated that miR-487a directly targeted the MAGI2 involved in the stability of PTEN. The down-regulation of miR-487a increased the expression of p-PTEN and PTEN, and reduced the expression of p-AKT in both cell lines. In addition, the results showed that NF-kappaB (p65) significantly increased the miR-487a promoter activity and expression, and TGF-β1 induced the increased miR-487a promoter activity via p65 in MCF-7 cells and MDA-MB-231 cells. Moreover, we further confirmed the expression of miR-487a was positively correlated with the lymph nodes metastasis and negatively correlated with the expression of MAGI2 in human breast cancer tissues. Overall, our results suggested that miR-487a could promote the TGF-β1-induced EMT, the migration and invasion of breast cancer cells by directly targeting MAGI2.     

GPER mediated estradiol reduces miR-148a to promote HLA-G expression in breast cancer

Breast cancer is the most common malignant diseases in women. miR-148a plays an important role in regulation of cancer cell proliferation and cancer invasion and down-regulation of miR-148a has been reported in both estrogen receptor (ER) positive and triple-negative (TN) breast cancer. However, the regulation mechanism of miR-148a is unclear. The role of estrogen signaling, a signaling pathway is important in development and progression of breast cancer. Therefore, we speculated that E2 may regulate miR-148a through G-protein-coupled estrogen receptor-1 (GPER). To test our hypothesis, we checked the effects of E2 on miR-148a expression in ER positive breast cancer cell MCF-7 and TN cancer cell MDA-MB-231. Then we used GPER inhibitor G15 to investigate whether GPER is involved in regulation of E2 on miR-148a. Furthermore, we analyzed whether E2 affects the expression of HLA-G, which is a miR-148a target gene through GPER. The results showed that E2 induces the level of miR-148a in MCF-7 and MDA-MB-231 cells, GPER mediates the E2-induced increase in miR-148a expression in MCF-7 and MDA-MB-231 cells and E2-GPER regulates the expression of HLA-G by miR-148a. In conclusion, our findings offer important new insights into the ability of estrogenic GPER signaling to trigger HLA-G expression through inhibiting miR-148a that supports immune evasion in breast cancer.     

Basic fibroblast growth factor (bFGF): mitogenic activity and binding sites in human breast cancer.

We investigated binding characteristics of basic fibroblast growth factor (bFGF) on membranes prepared from 4 human breast cancer cell lines and 38 primary BC biopsies. Competitive binding experiments were performed and analyzed using the "Ligand" program. Furthermore bFGF mitogenic activity was measured by [3H]thymidine incorporation into DNA from breast cancer cell lines. The presence of high-affinity binding sites was demonstrated in each cell type (MCF-7: Kd = 0.60 nM; T-47D: Kd = 0.55 nM; BT-20: Kd = 0.77 nM; MDA-MB-231: Kd = 0.34 nM). The presence of these high-affinity binding sites was confirmed with saturation experiments. A second class of low-affinity binding sites was detected in the 2 hormone-independent cells (BT-20: Kd = 2.9 nM; MDA-MB-231: Kd = 2.7 nM). bFGF stimulated the proliferation of MCF-7, T-47D, BT-20 but not MDA-MB-231 cell lines. With competition experiments, binding sites were detectable in 36/38 breast cancers; high-affinity binding sites (Kd less than 1 nM) were present in 19/36 cases and low-affinity binding sites (Kd greater than 2 nM) were present in 29/36 cases (the two classes of binding sites were present in 12 breast cancers). No relation between bFGF binding sites and node involvement, histologic type or grading of the tumor was evidenced. There were negative correlations (Spearman test) between total bFGF binding sites and estradiol receptor (P = 0.05) or progesterone receptor (P = 0.009). The demonstration of (1) bFGF specific binding sites in breast cancer membranes, and (2) bFGF growth stimulation of some breast cancer cell lines indicates that this factor may be involved directly in the growth of some breast cancers.     

Effects of triptolide from Tripterygium wilfordii on ERα and p53 expression in two human breast cancer cell lines

The aim of the study was to discover possible differential cytotoxicity of triptolide towards estrogen-sensitive MCF-7 versus estrogen-insensitive MDA-MB-231 human breast cancer cells. Considering that MCF-7 cells express functional Estrogen receptor α (ERα) and wild-type p53, whereas MDA-MB-231 cells which are ERα-negative express mutant p53, the anti-proliferation effect of triptolide on MCF-7 and MDA-MB-231 cells were examined, the apoptotic effect and cell cycle arrest caused by triptolide were investigated, ERα and p53 expression were also observed in this paper. The results showed that the anti-proliferation effects were induced by triptolide in both cell lines. But the value of IC₅₀ in MCF-7 cells for its anti-proliferation effect was about one tenth of that in MDA-MB-231 cells, which indicated that the effect is more potent in MCF-7 cells. Condensed chromatin or fragmented nuclei could be found in MCF-7 cells treated with only 40 nM triptolide but in MDA-MB-231 cells they couldn’t be observed until the concentration reached to 400 nM. Triptolide induced significant S cell cycle arrest along with the presence of sub-G0/G1 peak in MDA-MB-231 cells, whereas there was only slightly S cell cycle arrest on cell cycle distribution in MCF-7 cells. The role of p53 in two breast cancer cells was examined, the results showed that the mutant p53 in MDA-MB-231 cells was suppressed and the wild-type p53 in MCF-7 was increased. Moreover, triptolide could down regulate the expression of ERα in MCF-7 cells. The results showed that triptolide is much more sensitive to ERα-positive MCF-7 cells than to ERα-negative MDA-MB-231 cells, and the sensitivity is significantly associated with the ERα and p53 status.     

干扰TGFβRⅠ增加乳腺癌细胞MDA-MB-231对化疗药物的敏感性

转化生长因子β(transforming growth factorβ,TGFβ)与其受体(transforming growth factorβreceptor,TGFβR)结合激活下游信号通路,在肿瘤的发生发展和转移中具有重要意义,且已有迹象表明该通路可能介导肿瘤的化疗耐受.本研究构建了干扰转化生长因子βⅠ型受体(transforming growth factor receptor typeⅠ,TGFβRⅠ)的重组质粒pRNAT-U6.1/TGFβRⅠ-sh1,发现其可在mRNA和蛋白质水平均显著下调TGFβRⅠ的表达,P0.01.后将该干扰质粒转染乳腺癌细胞MCF-7/5Fu、MCF-7、MDA-MB-231、MDA-MB-453,建立了稳定的乳腺癌TGFβRⅠ干扰模型;MTS法检测上述4种细胞模型对5-氟尿嘧啶(5-fluorouracil,5-FU)和紫杉醇(taxol,TAX)的敏感性.结果显示,MCF-7、MCF-7/5Fu和MDA-MB-453细胞在干扰TGFβRⅠ之后对5-FU和TAX敏感性并未发生改变;但是间质表型的MDA-MB-231细胞在干扰TGFβRⅠ之后对5-FU和TAX的敏感性显著增加.由此可见,干扰TGFβRⅠ的表达阻断TGFβ信号通路,进而显著增加间质型乳腺癌细胞对化疗药物的敏感性,这为临床乳腺癌治疗提供了一定的理论依据.     

l-Leucine transport in human breast cancer cells (MCF-7 and MDA-MB-231): kinetics, regulation by estrogen and molecular identity of the transporter

The transport of l-leucine by two human breast cancer cell lines has been examined. l-Leucine uptake by MDA-MB-231 and MCF-7 cells was via a BCH-sensitive, Na⁺-independent pathway. l-Leucine uptake by both cell lines was inhibited by l-alanine, d-leucine and to a lesser extent by l-lysine but not by l-proline. Estrogen (17β-estradiol) stimulated l-leucine uptake by MCF-7 but not by MDA-MB-231 cells. l-Leucine efflux from MDA-MB-231 and MCF-7 cells was trans-stimulated by BCH in a dose-dependent fashion. The effect of external BCH on l-leucine efflux from both cell types was almost abolished by reducing the temperature from 37 to 4 °C. There was, however, a significant efflux of l-leucine under zero-trans conditions which was also temperature-sensitive. l-Glutamine, l-leucine, d-leucine, l-alanine, AIB and l-lysine all trans-stimulated l-leucine release from MDA-MB-231 and MCF-7 cells. In contrast, d-alanine and l-proline had little or no effect. The anti-cancer agent melphalan inhibited l-leucine uptake by MDA-MB-231 cells but had no effect on l-leucine efflux. Quantitative real-time PCR revealed that LAT1 mRNA was approximately 200 times more abundant than LAT2 mRNA in MCF-7 cells and confirmed that MDA-MB-231 cells express LAT1 but not LAT2 mRNA. LAT1 mRNA levels were higher in MCF-7 cells than in MDA-MB-231 cells. Furthermore, LAT1 mRNA was more abundant than CD98hc mRNA in both MDA-MB-231 and MCF-7 cells. The results suggest that system L is the major transporter for l-leucine in both MDA-MB-231 and MCF-7 cells. It is possible that LAT1 may be the major molecular correlate of system L in both cell types. However, not all of the properties of system L reflected those of LAT1/LAT2/CD98hc.     

Wnt pathway targeting reduces triple-negative breast cancer aggressiveness through miRNA regulation in vitro and in vivo

Triple-negative breast cancer, devoid of estrogen (ER), progesterone (PR), and human epidermal growth factor receptor 2 (HER-2) expression, is deprived of commonly used targeted therapies. MicroRNAs (miRNAs) are undergoing a revolution in terms of potentially diagnostic or therapeutic elements. Combining computational approaches, we enriched miRNA binding motifs of Wnt pathway-associated upregulated genes. Our in-depth bioinformatics, in vitro and in vivo analyses indicated that miR-381 targets main genes of the Wnt signaling pathway including CTNNB1, RhoA, ROCK1, and c-MYC genes. The expression level of miR-381 and target genes was assessed by quantitative real-time polymerase chain reaction (RT-qPCR) in MCF-7, MDA-MB-231, and MCF-10A as well as 20 breast cancer samples and normal tissues. Luciferase reporter assay was performed. Lentiviral particles containing miR-381 were used to evaluate the effect of miR-381 restoration on cell proliferation, migration, and invasion of the invasive triple-negative MDA-MB-231 cell line and also in a mouse model of breast cancer. The expression of miR-381 was lower than that of normal cells, especially in TNBC cell line and breast tissues. Luciferase assay results confirmed that miR-381 targets all the predicted 3′-untranslated regions (3′-UTRs). Upon miR-381 overexpression, the expression of target genes declined, and the migration and invasion potential of miR-381-receiving MDA-MB-231 cells decreased. In a mouse model of triple-negative breast cancer, miR-381 re-expression inhibited the invasion of cancer cells to lung and liver and prolonged the survival time of cancer cell-bearing mice. Therefore, miR-381 is a regulator of Wnt signaling and its re-expression provides a potentially effective strategy for inhibition of TNBC.     

Characterization of metabolic profile of intact non-tumor and tumor breast cells by high-resolution magic angle spinning nuclear magnetic resonance spectroscopy

¹H high-resolution magic angle spinning nuclear magnetic resonance (¹H HR–MAS NMR) spectroscopy was used to analyze the metabolic profile of an intact non-tumor breast cell line (MCF-10A) and intact breast tumor cell lines (MCF-7 and MDA-MB-231). In the spectra of MCF-10A cells, six metabolites were assigned, with glucose and ethanol in higher concentrations. Fifteen metabolites were assigned in MCF-7 and MDA-MB-231 ¹H HR–MAS NMR spectra. They did not show glucose and ethanol, and the major component in both tumor cells was phosphocholine (higher in MDA-MB-231 than in MCF-7), which can be considered as a tumor biomarker of breast cancer malignant transformation. These tumor cells also show acetone signal that was higher in MDA-MB-231 cells than in MCF-7 cells. The high acetone level may be an indication of high demand for energy in MDA-MB-231 to maintain cell proliferation. The higher acetone and phosphocholine levels in MDA-MB-231 cells indicate the higher malignance of the cell line. Therefore, HR–MAS is a rapid reproducible method to study the metabolic profile of intact breast cells, with minimal sample preparation and contamination, which are critical in the analyses of slow-growth cells.     

Effective chemopreventive activity of genistein against human breast cancer cells

Chemopreventive and cytotoxic effect of genistein against human breast cancer cell lines was investigated. Genistein inhibited cell proliferation in estrogen receptor-positive (MCF-7) and estrogen receptor-negative (MDA-MB-231) human breast carcinoma cell lines. Cytochrome P450 (CYP) 1A1-mediated ethoxyresorufin O-deethylase (EROD)activity was inhibited by genistein in a concentration-dependent manner. Genistein significantly inhibited 12-Otetradecanoylphorbol-13-acetate (TPA)-induced cyclooxygenase-2 activity and protein expression at the concentrations of 10 (p < 0.05), 25 (p < 0.05) and 50 mM (p < 0.01). In addition, ornithine decarboxylase (ODC) activity was reduced to 53.8 % of the control after 6 h treatment with 50 mM genistein in MCF-7 breast cancer cells. These results suggest that genistein could be of therapeutic value in preventing human breast cancer.