Genes In MCF-7 Cells Research Articles

The role of NF\u03baB in spheroid formation of human breast cancer cells cultured on the Random Positioning Machine

Human MCF-7 breast cancer cells were exposed to a Random Positioning Machine (RPM). After 24 hours (h) the cells grew either adherently within a monolayer (AD) or within multicellular spheroids (MCS). AD and MCS populations were separately harvested, their cellular differences were determined performing qPCR on genes, which were differently expressed in AD and MCS cells. Gene array technology was applied to detect RPM-sensitive genes in MCF-7 cells after 24 h. Furthermore, the capability to form multicellular spheroids in vitro was compared with the intracellular distribution of NF-kappaB (NFκB) p65. NFκB was equally distributed in static control cells, but predominantly localized in the cytoplasm in AD cells and nucleus in MCS cells exposed to the RPM. Gene array analyses revealed a more than 2-fold change of only 23 genes including some whose products are affected by oxygen levels or regulate glycolysis. Significant upregulations of the mRNAs of enzymes degrading heme, of ANXA1, ANXA2, CTGF, CAV2 and ICAM1, as well as of FAS, Casp8, BAX, p53, CYC1 and PARP1 were observed in MCS cells as compared with 1g-control and AD cells. An interaction analysis of 47 investigated genes suggested that HMOX-1 and NFκB variants are activated, when multicellular spheroids are formed.

Expression of STK11 gene and its promoter activity in MCF control and cancer cells

Serine/threonine kinase gene (STK11) is identified as tumor suppressor gene whose mutation can lead to Peutz–Jeghers syndrome (PJS). STK11 is emerging as a multifunctional protein, it activates 14 different AMP-activated protein kinase (AMPK) family members, important in the regulation of cell polarity, cell cycle arrest, energy and hemostasis. Present study was designed to evaluate STK11 mRNA expression in MCF-7 cancer and MCF-10 normal breast cells lines. mRNA expression was studied by real-time PCR. Further, human STK11 promoter construct was fused to a luciferase reporter and transfected into both MCF-7 and MCF-10 cells to identify the promoter activity in these cells. STK11 mRNA was found significantly higher in MCF-7 compared to MCF-10 cells (p value < 0.0005) indicating its role in the onset of breast cancer. Interestingly, it was found that the promoter activity of STK11 gene in MCF-7 cells was also significantly higher when compared to MCF-10 cells (p value < 0.005). Positive correlation was observed in promoter activity and gene expression (p = 0.048, r2 = 0.587). This study for the first time relates the altered STK11 gene expression in breast cancer cells with altered promoter activity. The present finding may shed light on the new therapeutic approaches against breast cancer by targeting gene or its promoter.

Identification of Non-Electrophilic Nrf2 Activators from Approved Drugs.

Oxidative damage can lead to a wide range of diseases. Nrf2 is an important transcription factor that regulates many of the cytoprotective enzymes involved in the oxidative stress response. Therefore, targeting the regulation of Nrf2 activation is one logical and effective strategy to prevent or lower the risk of oxidative stress-related diseases. Until now, most research has focused on electrophilic indirect Nrf2 activators, but the risk of ‘off-target’ effects may be associated with these activators. To find novel small non-electrophilic modulators of Nrf2, we started from chemical agents derived from a connectivity map (cMap) and identified 22 non-electrophilic potential Nrf2-activating drugs through a drug repositioning tactic. By determining the expression changes of antioxidant genes in MCF7 cells that were treated with the potential Nrf2 activators using quantitative real-time polymerase chain reaction RT-PCR (real-time polymerase chain reaction) (qRT-PCR), astemizole was found to have a greater scale of upregulating antioxidant genes NQO1, HO-1, and GCLM than the positive control d,l-sulforaphane, although the testing concentration was lower than that of the control. Astemizole is a good potential redox regulator and deserves more pharmacodynamic experimentation to test and verify its feasibility for use as an Nrf2 activator.

The expression of pluripotency genes regulates properties of cancer stem cells in MCF-7 breast cancer model.

e23018 Background: More than 1.6 million cases of breast cancer (BC) are diagnosed annually worldwide. Despite advances in diagnoses and treatment, BC remains the third leading cause of death in women. Metastases and chemotherapy resistance are the main factors contributing to BC mortality. The ability of tumor cells to overcome the drug-induced growth inhibition is now linked to a unique population of cancer initiating tumor cells, often referred as cancer stem cells (CSC). CSC represent a small fraction of tumor cells, therefore, currently used isolation protocols have a low yield and are poorly reproducible, hampering research on the role of these cells in cancer chemoresistance. We propose a novel approach to generate large quantities of CSC-like cells by genetic reprogramming of non-stem cancer cells. Methods: We postulate that CSC-enriched cell line can be developed in vitro by upregulating of proteins controlling cancer cell pluripotency including Oct4, Sox2, NANOG, KLF4 and c-Myc. Increased transcriptional and translational activity of these genes in MCF-7 cells was demonstrated by real time-PCR and Western blot. Proliferation and migration of cells overexpressing Oct4, Sox2, NANOG, KLF4 and c-Myc were analyzed as well. Also, changes in CSC population counts and their sensitivity to chemotherapy were investigated using sphere formation assay. Results: We found that cell proliferation rate was correlated with the expression level of c-Myc and Oct4. Increased CSC counts were found in cells with overexpressed Oct4 (62.7%), KLF4 (97%) and NANOG (121.3%) proteins as compared to the parental cells. Overexpression of SOX2, NANOG and KLF4 significantly increased CSC resistance to docetaxel (83,3±6,8; 93,3±4,5 and 80,3±5,0 spheres respectively) when compared to the original cells (48,3±3,0 spheres). Conclusions: We conclude that overexpression of pluripotency proteins Oct4, Sox2, NANOG, KLF4 and c-Myc changes the CSC counts and proliferation capacity of BC cells. Acknowledgements: The study was funded by RFBR, according to the research project No. 16-34-60210 mol_а_dk, and by Russian Government Program of Competitive Growth of Kazan Federal University.

15-Deoxy-Δ12,14-prostaglandin J2 stabilizes hypoxia inducible factor-1α through induction of heme oxygenase-1 and direct modification ofprolyl-4-hydroxylase 2

15-Deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2), a representative J-series cyclopentenone prostaglandin, has biphasic roles in cell proliferation and apoptosis. Hypoxia inducible factor-1 (HIF-1) regulates expression of various genes involved in tumor growth and angiogenesis. In the present study, treatment of human breast cancer (MCF-7) cells with 15d-PGJ2 resulted in the accumulation of the α-subunit of HIF-1. Pretreatment with zinc protoporphyrin IX, a pharmacological inhibitor of heme oxygenase-1 (HO-1), as well as siRNA knockdown of HO-1 gene in MCF-7 cells attenuated 15d-PGJ2-mediated HIF-1α accumulation. 15d-PGJ2 treatment increased intracellular production of reactive oxygen species (ROS), which was mediated by HO-1 induction. Preincubation of MCF-7 cells with trolox, a water-soluble form of vitamin E, attenuated 15d-PGJ2-induced HIF-1α expression although HO-1 expression was unchanged. This finding suggests that ROS accumulated as a consequence of HO-1 up-regulation can enhance HIF-1α expression in MCF-7 cells treated with 15d-PGJ2. Alternatively, 15d-PGJ2 was found to covalently bind to HIF-1α prolyl-4-hydroxylase 2 (PHD2) in MCF-7 cells, which hampers the proline hydroxylation of HIF-1α, thereby disrupting ubiquitin-dependent proteasomal degradation of this transcription factor. Pretreatment with thiol reducing agents blunted 15d-PGJ2-induced HIF-1α stabilization, indicative of a cysteine residue as a direct target of 15d-PGJ2. Molecular docking analysis suggests that 15d-PGJ2 preferentially binds to PHD2 in the vicinity of the Cys201 residue based on binding energies and carbon–sulfur distances. In summary, 15d-PGJ2 stabilizes HIF-1α in MCF-7 cells through HO-1 induction with subsequent ROS generation and also through direct modification of PHD2.

Docetaxel-Chitosan nanoparticles for breast cancer treatment: cell viability and gene expression study.

Docetaxel acts through the inhibition of tubulin polymerization and reduction in the expression of BCL-2 gene. In this study, nanoparticles containing Docetaxel were prepared and their effects on the gene expression levels of BCL-2 and BAX genes were investigated. The drug was first conjugated to chitosan, and the nanoparticles were assembled in the presence of hyaluronic acid. Conjugations were confirmed by 1 H-NMR, and the obtained nanoparticles were characterized by dynamic light scattering and SEM. Cytotoxicity of the nanoparticles, cellular uptake, and cell death were evaluated. Finally, the effect of nanoparticles on the expression of BAX and BCL-2 genes in MCF-7 cells were investigated through real-time PCR. The results revealed that the prepared NPs had spherical shape with narrow size distribution of <200nm with positive zeta potentials. In vitro cytotoxicity of Cs nanoparticles and free Docetaxel investigations revealed that increasing the treatment time with nanoparticles led to decrease in the rate of cell viability. BAX and BCL-2 gene expressions were decreased in nanoparticle-treated cells in comparison with intact cells, while the BAX/BCL-2 ratio was significantly elevated compared with free drug-treated cells after 72h. Docetaxel-conjugated NPs may offer a promising treatment with low off-target toxicity for breast cancer.

Role of Zn doping in oxidative stress mediated cytotoxicity of TiO2 nanoparticles in human breast cancer MCF-7 cells

We investigated the effect of Zn-doping on structural and optical properties as well as cellular response of TiO2 nanoparticles (NPs) in human breast cancer MCF-7 cells. A library of Zn-doped (1–10 at wt%) TiO2 NPs was prepared. Characterization data indicated that dopant Zn was incorporated into the lattice of host TiO2. The average particle size of TiO2 NPs was decreases (38 to 28 nm) while the band gap energy was increases (3.35 eV–3.85 eV) with increasing the amount of Zn-doping. Cellular data demonstrated that Zn-doped TiO2 NPs induced cytotoxicity (cell viability reduction, membrane damage and cell cycle arrest) and oxidative stress (reactive oxygen species generation & glutathione depletion) in MCF-7 cells and toxic intensity was increases with increasing the concentration of Zn-doping. Molecular data revealed that Zn-doped TiO2 NPs induced the down-regulation of super oxide dismutase gene while the up-regulation of heme oxygenase-1 gene in MCF-7 cells. Cytotoxicity induced by Zn-doped TiO2 NPs was efficiently prevented by N-acetyl-cysteine suggesting that oxidative stress might be the primarily cause of toxicity. In conclusion, our data indicated that Zn-doping decreases the particle size and increases the band gap energy as well the oxidative stress-mediated toxicity of TiO2 NPs in MCF-7 cells.

Multiplex bioimaging of piRNA molecular pathway-regulated theragnostic effects in a single breast cancer cell using a piRNA molecular beacon.

Recently, PIWI-interacting small non-coding RNAs (piRNAs) have emerged as novel cancer biomarkers candidate because of their high expression level in various cancer types and role in the control of tumor suppressor genes. In this study, a novel breast cancer theragnostics probe based on a single system targeting the piRNA-36026 (piR-36026) molecular pathway was developed using a piR-36026 molecular beacon (MB). The piR-36026MB successfully visualized endogenous piR-36026 biogenesis, which is highly expressed in MCF7 cells (a human breast cancer cell line), and simultaneously inhibited piR-36026-mediated cancer progression invitro and invivo. We discovered two tumor suppressor proteins, SERPINA1 and LRAT, that were directly regulated as endogenous piR-36026 target genes in MCF7 cells. Furthermore, multiplex bioimaging of a single MCF7 cell following treatment with piR-36026MB clearly visualized the direct molecular interaction of piRNA-36026 with SERPINA1 or LRAT and subsequent molecular therapeutic responses including caspase-3 and PI in the nucleus.

Cyclin C interacts with steroid receptor coactivator 2 and upregulates cell cycle genes in MCF-7 cells

Steroid receptor coactivator 2 (SRC-2) is a coactivator that regulates nuclear receptor activity. We previously reported that SRC-2 protein is degraded through the action of cAMP-dependent protein kinase A (PKA) and cAMP response element binding protein (CREB). In the study presented here, we aimed to identify proteins that interact with and thereby regulate SRC-2. We isolated cyclin C (CCNC) as an interacting partner with the SRC-2 degradation domain aa 347-758 in a yeast two-hybrid assay and confirmed direct interaction in an in vitro assay. The protein level of SRC-2 was increased with CCNC overexpression in COS-1 cells and decreased with CCNC silencing in COS-1 and MCF-7 cells. In a pulse-chase assay, we further show that silencing of CCNC resulted in a different SRC-2 degradation pattern during the first 6h after the pulse. Finally, we provide evidence that CCNC regulates expression of cell cycle genes upregulated by SRC-2. In conclusion, our results suggest that CCNC temporarily protects SRC-2 against degradation and this event is involved in the transcriptional regulation of SRC-2 cell cycle target genes.

Induction of cell cycle arrest and apoptosis by betulinic acid-rich fraction from Dillenia suffruticosa root in MCF-7 cells involved p53/p21 and mitochondrial signalling pathway

Ethnopharmacological relevanceDillenia suffruticosa (Family: Dilleniaceae) or commonly known as “Simpoh air” in Malaysia, is traditionally used for treatment of cancerous growth including breast cancer. Aim of the studyD. suffruticosa root dichloromethane extract (DCM-DS) has been reported to induce G0/G1 phase cell cycle arrest and apoptosis in caspase-3 deficient MCF-7 breast cancer cells. The present study was designed to investigate the involvement of p53/p21 and mitochondrial pathway in DCM-DS-treated MCF-7 cells as well as to identify the bioactive compounds responsible for the cytotoxicity of DCM-DS. Materials and methodsExtraction of D. suffruticosa root was performed by the use of sequential solvent procedure. GeXP-based multiplex system was employed to investigate the expression of p53, p21, Bax and Bcl-2 genes in MCF-7 cells treated with DCM-DS. The protein expression was then determined using Western blot analysis. The bioactive compounds present in DCM-DS were isolated by using column chromatography. The structure of the compounds was elucidated by using nuclear magnetic resonance spectroscopy. The cytotoxicity of the isolated compounds towards MCF-7 cells was evaluated by using MTT assay. The percentage of betulinic acid (BA) in DCM-DS was determined by HPLC analysis. ResultsThe expression of p53 was significantly up-regulated at protein level. The expression of p21 at both gene and protein levels was significantly up-regulated upon treatment with DCM-DS, suggesting that the induction of G0/G1 phase cell cycle arrest in MCF-7 cells was via p53/p21 pathway. Bcl-2 protein was down-regulated with no change at the mRNA level, postulating that post-translational modification has occurred resulting in the degradation of Bcl-2 protein. Overall, treatment with DCM-DS increased the ratio of Bax/Bcl-2 that drove the cells to undergo apoptosis. A total of 3 triterpene compounds were isolated from DCM-DS. Betulinic acid appears to be the most major and most cytotoxic compound in DCM-DS. ConclusionDCM-DS induced cell cycle arrest and apoptosis in MCF-7 cells via p53/p21 pathway. In addition, DCM-DS induced apoptosis by increasing the ratio of Bax/Bcl-2. Betulinic acid, which is one of the major compounds, is responsible for the cytotoxicity of the DCM-DS. Therefore, BA can be used as a marker for standardisation of herbal product from D. suffruticosa. DCM-DS can also be employed as BA-rich extract from roots of D. suffruticosa for the management of breast cancer.

Pharmacological relevance of endoxifen in a laboratory simulation of breast cancer in postmenopausal patients.

Tamoxifen is metabolically activated via a CYP2D6 enzyme system to the more potent hydroxylated derivatives 4-hydroxytamoxifen and endoxifen. This study addresses the pharmacological importance of endoxifen by simulating clinical scenarios in vitro. Clinical levels of tamoxifen metabolites in postmenopausal breast cancer patients previously genotyped for CYP2D6 were used in vitro along with clinical estrogen levels (estrone and estradiol) in postmenopausal patients determined in previous studies. The biological effects on cell growth were evaluated in a panel of estrogen receptor-positive breast cancer cell lines via cell proliferation assays and real-time polymerase chain reaction (PCR). Data were analyzed with one- and two-way analysis of variance and Student's t test. All statistical tests were two-sided. Postmenopausal levels of estrogen-induced proliferation of all test breast cancer cell lines (mean fold induction ± SD vs vehicle control: MCF-7 = 11 ± 1.74, P < .001; T47D = 7.52 ± 0.72, P < .001; BT474 = 1.75 ± 0.23, P < .001; ZR-75-1 = 5.5 ± 1.95, P = .001. Tamoxifen and primary metabolites completely inhibited cell growth regardless of the CYP2D6 genotype in all cell lines (mean fold induction ± SD vs vehicle control: MCF-7 = 1.57 ± 0.38, P = .54; T47D = 1.17 ± 0.23, P = .79; BT474 = 0.96 ± 0.2, P = .98; ZR-75-1 = 0.86 ± 0.67, P = .99). Interestingly, tamoxifen and its primary metabolites were not able to fully inhibit the estrogen-stimulated expression of estrogen-responsive genes in MCF-7 cells (P < .05 for all genes), but the addition of endoxifen was able to produce additional antiestrogenic effect on these genes. The results indicate that tamoxifen and other metabolites, excluding endoxifen, completely inhibit estrogen-stimulated growth in all cell lines, but additional antiestrogenic action from endoxifen is necessary for complete blockade of estrogen-stimulated genes. Endoxifen is of supportive importance for the therapeutic effect of tamoxifen in a postmenopausal setting.

Induction of cell cycle arrest and apoptosis in caspase-3 deficient MCF-7 cells by Dillenia suffruticosa root extract via multiple signalling pathways.

BackgroundDillenia suffruticosa root dichloromethane extract (DCM-DS) has been reported to exhibit strong cytotoxicity towards breast cancer cells. The present study was designed to investigate the cell cycle profile, mode of cell death and signalling pathways of DCM-DS-treated human caspase-3 deficient MCF-7 breast cancer cells.MethodsDillenia suffruticosa root was extracted by sequential solvent extraction. The anti-proliferative activity of DCM-DS was determined by using MTT assay. The mode of cell death was evaluated by using inverted light microscope and Annexin-V/PI-flow cytometry analysis. Cell cycle analysis and measurement of intracellular reactive oxygen species (ROS) were performed by using flow cytometry. MCF-7 cells were co-treated with antioxidants α-tocopherol and ascorbic acid to evaluate whether the cell death was mainly due to oxidative stress. GeXP-based multiplex system was employed to investigate the expression of apoptotic, growth and survival genes in MCF-7 cells. Western blot analysis was performed to confirm the expression of the genes.ResultsDCM-DS was cytotoxic to the MCF-7 cells in a time-and dose-dependent manner. The IC50 values of DCM-DS at 24, 48 and 72 hours were 20.3 ± 2.8, 17.8 ± 1.5 and 15.5 ± 0.5 μg/mL, respectively. Cell cycle analysis revealed that DCM-DS induced G0/G1 and G2/M phase cell cycle arrest in MCF-7 cells at low concentration (12.5 and 25 μg/mL) and high concentration (50 μg/mL), respectively. Although Annexin-V/PI-flow cytometry analysis has confirmed that DCM-DS induced apoptosis in MCF-7 cells, the distinct characteristics of apoptosis such as membrane blebbing, chromatin condensation, nuclear fragmentation and formation of apoptotic bodies were not observed under microscope. DCM-DS induced formation of ROS in MCF-7 cells. Nevertheless, co-treatment with antioxidants did not attenuate the cell death at low concentration of DCM-DS. The pro-apoptotic gene JNK was up-regulated whereby anti-apoptotic genes AKT1 and ERK1/2 were down-regulated in a dose-dependent manner. Western blot analysis has confirmed that DCM-DS significantly up-regulated the expression of pro-apoptotic JNK1, pJNK and down-regulated anti-apoptotic AKT1, ERK1 in MCF-7 cells.ConclusionDCM-DS induced cell cycle arrest and apoptosis in MCF-7 cells via multiple signalling pathways. It shows the potential of DCM-DS to be developed to target the cancer cells with mutant caspase-3.

Estrogen-Responsive Genes Overlap with Triiodothyronine-Responsive Genes in a Breast Carcinoma Cell Line

It has been well established that estrogen plays an important role in the progression and treatment of breast cancer. However, the role of triiodothyronine (T3) remains controversial. We have previously shown its capacity to stimulate the development of positive estrogen receptor breast carcinoma, induce the expression of genes (PR, TGF-alpha) normally stimulated by estradiol (E2), and suppress genes (TGF-beta) normally inhibited by E2. Since T3 regulates growth hormones, metabolism, and differentiation, it is important to verify its action on other genes normally induced by E2. Therefore, we used DNA microarrays to compare gene expression patterns in MCF-7 breast adenocarcinoma cells treated with E2 and T3. Several genes were modulated by both E2 and T3 in MCF-7 cells (Student's t-test, P < 0.05). Specifically, we found eight genes that were differentially expressed after treatment with both E2 and T3, including amphiregulin, fibulin 1, claudin 6, pericentriolar material 1, premature ovarian failure 1B, factor for adipocyte differentiation-104, sterile alpha motif domain containing 9, and likely ortholog of rat vacuole membrane protein 1 (fold change > 2.0, pFDR < 0.05). We confirmed our microarray results by real-time PCR. Our findings reveal that certain genes in MCF-7 cells can be regulated by both E2 and T3.

The trefoil factor 1 (TFF1) protein involved in doxorubicin-induced apoptosis resistance is upregulated by estrogen in breast cancer cells

Trefoil factor 1 (TFF1) is a small secretory protein expressed in various types of carcinomas including breast cancer. The TFF1 gene contains an estrogen response element and its expression can be regulated by estrogen. Previous reports showed that TFF1 could protect cells from induced apoptosis invitro. In the present study, the effect of estrogen on the promotion of doxorubicin-induced apoptosis resistance and the role of TFF1 in this process was demonstrated using the MCF-7 breast cancer cell model. Stable knockdown of the TFF1 gene in MCF-7 cells was generated and used to test the sensitivity to doxorubicin treatment compared to mock control cells in the presence or absence of 17β-estradiol. The apoptotic cells were measured by flow cytometry. The results showed that with the stimulation of apoptosis by doxorubicin, 17β-estradiol could suppress this process in mock cells but not in TFF1 knockdown cells. Moreover, using a viable cell counting method, it was shown that the anti-TFF1 antibody could reverse the anti-apoptotic effect of estrogen in mock cells and recombinant TFF1 could recover doxorubicin-induced cell death in TFF1 knockdown cells. This process, however, could not be inhibited by fulvestrant, an estrogen antagonist. An apoptosis protein array experiment reflected the role of the anti-oxidative enzyme catalase in estrogen and TFF1-modulated apoptosis and this was confirmed by enzymatic assay. These phenomena determine the role of TFF1 in estrogen-promoted resistance to apoptosis induced by doxorubicin in MCF-7 breast cancer cells. The TFF1 gene may be a target for enhancing the sensitivity to chemotherapy in breast cancer treatment.

Emodin induces cytotoxic effect in human breast carcinoma MCF-7 cell through modulating the expression of apoptosis-related genes

Context: The poor prognostic outcome of breast cancer is largely due to its resistance to cancer therapies. Development of therapeutic agents that can inhibit growth and induce apoptosis in breast cancer cells can help solve the problem. Emodin is an active anthraquinone that has been reported to have diverse biological effects.Objective: In this study, the anticancer effects of emodin on growth inhibition, apoptosis induction and the expression of apoptosis-related genes in MCF-7 cells were investigated.Materials and methods: Growth inhibition induced by emodin was investigated by the MTS assay and the colony formation assay; while emodin-induced apoptosis was determined by the COMET assay and DNA fragmentation detection. Emodin (35 μM)-induced alterations in the expression of apoptotic-related genes were detected by using real-time PCR.Results: Emodin had significant growth inhibitory effects on MCF-7 cells with IC50 = 7.22 µg/ml (∼30 μM). It also exerted a concentration-dependant inhibitory effect on the colony-forming ability of MCF-7 cells with IC50 = 7.60 µg/ml (∼30 µM). Hallmarks of apoptosis, such as single-strand DNA breakage and DNA fragmentation, were observed in emodin-treated MCF-7 cells. The gene expression of Fas ligand (FASL) was up-regulated (p < 0.01) but those of MCL1, CCND1 and C-MYC were down-regulated (p < 0.05) in emodin-treated MCF-7 cells.Discussion and conclusion: This study indicated that emodin could induce growth inhibition and apoptosis in MCF-7 cells through the modulation of the expression of apoptosis-related genes. The growth inhibitory effects of emodin might involve both the intrinsic and the extrinsic apoptotic pathways and cell cycle arrest.

Influence of triptolide on P53/P73 gene methylation and inhibition effect against proliferation of breast carcinoma MCF-7 cells

Objective To study the effect of triptolide(TP) on the proliferation of breast carcinoma cell line MCF-7 and its association with P53/P73 gene expression and methylation.Methods MCF-7 cells were treated with different concentrations of TP(10 ng/ml,20 ng/ml,and 40 ng/ml),and the proliferation of MCF-7 cells was measured by MTT method.The expressions of methyltransferase DNMT1,DNMT3a and DNMT3b mRNA were measured by RT-PCR in MCF-7 cells,P53/P73 gene methylation was analyzed by methylation specific PCR,and the protein expression of p53/P73 in MCF-7 cells was examined by Western blotting assay.Results TP inhibited the proliferation of MCF-7 cells in a dose-dependent manner(P0.05,P0.01),with the inhibitory rate being(70.1±3.52)% at 40 ng/ml TP,and the IC50 of TP was 20 ng/ml.TP significantly inhibited DNMT1,DNMT3a,and DNMT3b mRNA expression in MCF-7 cells(P0.05,P0.01),and it also significantly inhibited methylation of P53 promoter region.TP increased P53 gene expression at 20 ng/ml and the increase was significant at 40 ng/ml(P0.01).TP reversed the hypermethylation of P73 gene in MCF-7 cells;it also significantly increased P73 mRNA expression at 10 ng/ml(P0.05),and the increase was in a dose-dependent manner.Western blotting analysis showed that TP(20 ng/ml) increased the protein expression of P53 and P73 in MCF-7 cells.Conclusion TP can promote the expression of P53 and P73 genes through inhibiting methyltransferase-dependent gene methylation,and further inhibit the proliferation of MCF-7 cells.

Abstract 1074: Genome-wide analysis of FOXM1 binding and involvement of FOXM1 in cancer stem cell and metastasis properties of endocrine-sensitive and resistant breast cancer cells.

Abstract FOXM1 is a transcription factor that coordinates expression of late cell cycle-related genes. Elevated expression of FOXM1 in breast cancer correlates with a more aggressive tumor phenotype and, as we have previously shown, is associated with resistance to endocrine treatment via 14-3-3ζ protein signaling (Bergamaschi A. et al. Breast Cancer Research 2011, 13:R7). To better understand the role that FOXM1 plays in endocrine resistance and aggressiveness we analyzed its genome-wide DNA binding and effects on gene expression. We mapped genome-wide FOXM1 binding events, by chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq), in hormone-sensitive and resistant breast cancer cell lines after estrogen or tamoxifen treatments. We also investigated the relationship between FOXM1, estrogen receptor-α and MAPK chromatin binding events by clustering analysis of Chip-seq data and identified specific clusters of colocalized binding events as identifiers for different functional gene classes. Clusters enriched in colocalized factor binding sites were associated with genes involved in maintenance of stem cell properties and genes involved in invasion and metastasis (Rho-GTPases). Binding profiles were also integrated with expression data from FOXM1 knockdown experiments, to reveal specific FOXM1 transcriptional networks. Cell studies showed the relevance of FOXM1 in breast cancer endocrine resistance and development of metastasis. We modulated the levels of FOXM1 and some newly discovered FOXM1 regulated genes in MCF7 cells and assessed their roles in hormone resistance and breast cancer aggressiveness by several functional studies. Increased expression levels of FOXM1 were associated with an increase in the cancer stem cell population. Moreover, FOXM1 overexpressing cell lines exhibited invadopodia which correlated with an increased invasion potential. The use of a specific and selective FOXM1 inhibitor proved to be especially effective in restoring endocrine sensitivity and in decreasing breast cancer aggressiveness. Collectively, our findings define FOXM1 as a master regulator of Rho-GTPase and stem cell marker expression. Dysregulation of the FOXM1 pathway promotes breast cancer progression and therefore makes FOXM1 a relevant therapeutic target to be considered for reducing invasiveness and enhancing response to endocrine and other therapies. Supported by Department of Defense grant W81XWH-09-1-0398 and a grant from The Breast Cancer Research Foundation). Citation Format: Anna Bergamaschi, Zeynep Madak-Erdogan, Hailing Lu, Benita S. Katzenellenbogen. Genome-wide analysis of FOXM1 binding and involvement of FOXM1 in cancer stem cell and metastasis properties of endocrine-sensitive and resistant breast cancer cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1074. doi:10.1158/1538-7445.AM2013-1074

Abstract 4759: HOXB7 functions as a co-activator of estrogen receptor in the development of tamoxifen resistance.

Abstract Background: Multiple factors including long term treatment with tamoxifen are involved in the development of selective estrogen receptor modulator (SERM)-resistance in ERα positive breast cancer. Increased expression of HER family members can also directly alter cellular responses to tamoxifen, but the mechanism underlying the increased expression of the HERs is not clear. In this report we show that HOXB7 is an upstream regulator of HER2 and ER expression. Results: Overexpression of HOXB7 results in upregulation of HER2 and ERα target genes, while knockdown of HOXB7 with siRNA in tamoxifen-resistant cell lines causes decrease of HER2 and ERα target genes expression and loss of tamoxifen resistance. To mediate upregulation of HER2 and ER-target genes occurring in tamoxifen resistance, the HOXB7-ERα complex recruits ERα coactivators and promotes HER2- and ER-target genes transcriptional activity through direct binding to the HER2 enhancer and regulatory regions of ER target genes. However, depletion of HOXB7 negatively affects the binding affinity of its cofactors to the HER2 enhancer element and ER-binding sites. Also, it is likely that miR196a controls HOXB7 expression; reducing miR196a levels in tamoxifen-resistant cells causes an increase of HOXB7 expression. Overexpression of miR196a sensitizes MCF-7 tamoxifen resistant cells to tamoxifen through downregulation of HER2 and ER-target genes while inhibition of miR196a by anti-miR196a inhibitors increases tamoxifen resistance through the upregulation of HER and ER target genes in MCF-7 cells. Further, miRNA 196a is regulated by c-MYC which undergoes stabilization through the EGFR-HER2 signaling pathway. Depletion of c-MYC by MYC shRNA enhances tamoxifen sensitivity by increasing the level of miR196a transcripts. Also, by c-MYC ChIP assay, we found that c-MYC inhibits miR196a expression through direct binding to its promoter region. Conclusions: Overexpression of HOXB7 is a key event in the initiation and maintenance of tamoxifen resistance. These studies suggest that HOXB7 acts as a key regulator orchestrating two major groups of target molecules, ERα and HER2, in the oncogene hierarchy. Blocking MYC expression or reexpression of miR196a in TAM-R cells may provide novel strategies for reversing SERM-resistance. Therefore, we have provided additional evidence that supports the thesis that functional antagonism of HOXB7 has the potential to circumvent tamoxifen resistance. Citation Format: Kideok Jin, Wei Wen Teo, Takahiro Yoshida, Sunju Park, Saraswati Sukumar. HOXB7 functions as a co-activator of estrogen receptor in the development of tamoxifen resistance. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4759. doi:10.1158/1538-7445.AM2013-4759

Abstract C85: FOXM1-dependent gene expression program controls cancer stem cell and metastasis properties of breast cancer cells

Abstract The transcription factor FOXM1 coordinates expression of late cell cycle-related genes. Elevated expression of FOXM1 in breast cancer correlates with a more aggressive tumor phenotype and, as we have previously shown, is associated with resistance to endocrine treatment via 14-3-3ζ protein signaling (Bergamaschi A. et al. Breast Cancer Research 2011, 13:R7). To better understand the role that FOXM1 plays in endocrine resistance and aggressiveness, we analyzed its genome-wide DNA binding and effects on gene expression. We mapped genome-wide FOXM1 binding events, by chromatin immunoprecipitation followed by high-throughput sequencing (ChIP-seq), in breast cancer cell lines after estrogen or tamoxifen treatments. We also investigated the relationship between FOXM1, estrogen receptor-α and MAPK chromatin binding events by clustering analysis of Chip-seq data and identified specific clusters of colocalized binding events as identifiers for different functional gene classes. Clusters enriched in colocalized factor binding sites were associated with genes involved in maintenance of stem cell properties and genes involved in invasion and metastasis (Rho-GTPases). Binding profiles were also integrated with expression data from FOXM1 knockdown experiments, to reveal specific FOXM1 transcriptional networks. Cell studies showed the relevance of FOXM1 in breast cancer endocrine resistance and development of metastasis. We modulated the levels of FOXM1 and some newly discovered FOXM1 regulated genes in MCF7 cells and assessed their roles in hormone resistance and breast cancer aggressiveness by several functional studies. Increased expression levels of FOXM1 were associated with an increase in the cancer stem cell population. Moreover, FOXM1 overexpressing cell lines exhibited invadopodia which correlated with an increased invasion potential. The use of a specific and selective FOXM1 inhibitor proved to be especially effective in restoring endocrine sensitivity and in decreasing breast cancer aggressiveness. Collectively, our findings define FOXM1 as a master regulator of Rho-GTPase and stem cell marker expression. Dysregulation of the FOXM1 pathway promotes breast cancer progression and therefore makes FOXM1 a relevant therapeutic target to be considered for reducing invasiveness and enhancing response to endocrine and other therapies. Citation Format: Anna Bergamaschi, Zeynep Madak-Erdogan, Hailing Lu, Benita S. Katzenellenbogen. FOXM1-dependent gene expression program controls cancer stem cell and metastasis properties of breast cancer cells. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Invasion and Metastasis; Jan 20-23, 2013; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2013;73(3 Suppl):Abstract nr C85.

Bisphenol A alone or in combination with estradiol modulates cell cycle- and apoptosis-related proteins and genes in MCF7 cells

Bisphenol A (BPA) with its estrogenic properties is intensively studied since its presence in the environment and human body. Besides other adverse effects, the compound is suspected of contributing to hormone-related cancers. The present study was aimed to investigate short time (24 h) effects of BPA on the important genes/proteins involved in apoptosis and the cell cycle progression in the breast cancer cells MCF7. The experimental design covered cell treatment with a broad BPA concentration scale: 10-12M corresponding to ubiquitous exposure, 10-9M relevant to human levels, and 10-6M as experimentally usual. We further investigated the combined effects of low BPA dose (10-12M) with physiological concentration of estradiol (E2) (10-9M). The expression of particular proteins and genes was studied by Western blotting and real time RT-PCR, respectively. Estrogenic effect of BPA was confirmed in the following checkpoints: mRNA expression of estrogen receptor α, expression of cyclin D1 and A2 proteins and CCNA2 gene, Bax and Bcl2 protein levels. For both cyclins protein levels, the maximum stimulation was present at 10-9M BPA and the effects resembled the "inverted U"-shape, a nonmonotonic dose-response curve reported for the action of xenoestrogens. The combined effect of low BPA dose with physiological E2 concentration differ from those of individual compounds, the character of stimulatory response is neither additive nor synergistic. The results obtained strongly support the evidence of BPA and BPA+E2 proliferation-promoting effects in human breast carcinoma cells, even after short time exposure, partially via reduced rate of apoptosis by the action of BPA+E2.