Project description:We report the chromatin binding sites of HOXB7 transcription factor in BT-474 breast cancer cell line using ChIP-sequencing. We validated the chromatin binding sites in BT-474, MDA-MB-361, MCF7 and T-47D breast cancer cell lines using ChIP-qPCR. The ChIP experiments have been performed using HOXB7 antibody and IgG non-specific antibody as a negative control. The direct downstream target genes of HOXB7 were identified by analyzing the expression of genes located nearby HOXB7 binding sites in HOXB7 knockdown versus control cells using qRT-PCR.
Project description:We report the chromatin binding sites of HOXB7 transcription factor in BT-474 breast cancer cell line using ChIP-sequencing. We validated the chromatin binding sites in BT-474, MDA-MB-361, MCF7 and T-47D breast cancer cell lines using ChIP-qPCR. The ChIP experiments have been performed using HOXB7 antibody and IgG non-specific antibody as a negative control. The direct downstream target genes of HOXB7 were identified by analyzing the expression of genes located nearby HOXB7 binding sites in HOXB7 knockdown versus control cells using qRT-PCR. Examination of chromatin binding sites of HOXB7 in BT-474 breast cancer cell line using ChIP-seq. Four parallel IgG samples were sequenced, merged together and used as a control data set. Two parallel HOXB7 ChIP samples were sequenced and merged for each replicate, AF1 and AF2. Both HOXB7 ChIP replicates (AF1 and AF2) contained approximately the same amount of reads as the merged IgG control data set.
Project description:Multiple-condition experiment was desinged to be any number of conditions in an experiment without replicate observations for microarray and used to identify genes differentially expressed between different pairs of conditions (treatments).<br> In this study we used breast cancer stable cell lines for overexpressing and silencing annexin A1 (ANXA1), which belongs to a family of -dependent phospholipid binding proteins and are preferentially located on the cytosolic face of the plasma membrane. Cell lines overexpressing ANXA1 (MDA_MB-453/cDNA) were generated by introducing retroviral vectors containing ANXA1 cDNA (pBabe/ANXA1 cDNA) into breast cancer cell line MDA-MB-453 (a low expressor of ANXA1). Breast cancer cell line BT-474, a high expressor of ANXA1, was infected with ANXA1 siRNA-plasmid viruses to knockdown ANAXAI expressor (BT-474/siRNA) where nucleotides corresponding to siRNA were synthesized and ligated into the pLNCX retroviral vector [35,36]. We also used a pLNCX/U6 empty vector to infect BT-474 and obtained an empty vector expressor. Therefore, 5 breast cancer cell lines (MDA_MB-453, MDA_MB-453/cDNA, BT-474, BT-474/siRNA, and BT-474/U6) are attributed to two genotypes: MDA_MB-453 and BT-474. MCE was performed for microarray analysis with these 5 breast cancer cell lines, that is, only one sample was drawn from each breast cancer cell line.
Project description:Accumulating evidence suggests that the androgen receptor (AR) and its endogenous ligands influence disease progression in breast cancer (BCa). However, AR-mediated changes in BCa differ among the various BCa subtypes according to their hormone receptor profile (i.e presence/absence of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2, (HER2)). Thus, we explored the androgen-regulated transcriptomic changes in the ER+PR+HER2+ BCa cell line, BT-474, and compared them with PR-mediated changes. Methods: We performed RNA sequencing analysis, in treated BT-474 cells with dihydrotestosterone (DHT) and progesterone (PROG). Validation of the top ten differentially androgen-regulated genes and a number of other genes found in enriched signaling pathways was performed by qRT-PCR in BT-474 and other BCa cell lines. A parallel reaction monitoring targeted proteomic approach was developed for the verification of selected transcripts at the protein level. Results: We detected 19,450 transcripts, of which 224 were differentially regulated after DHT treatment. The increased expression of two well-known androgen-regulated genes, KLK2 (p<0.05) and KLK3 (p<0.001), confirmed the successful androgen stimulation in BT-474 cells. The transcription factor, ZBTB16, was the most highly upregulated gene, with ~1000-fold change (p<0.001). Pathway enrichment analysis revealed downregulation of the DNA replication processes (p<0.05), and upregulation of the androgen signaling and fatty acid metabolism pathways (p<0.05). Changes related to PROG-treatment showed opposite effects in gene expression than DHT treatment. Similar expression profiles were observed among other BCa cell lines expressing high levels of AR (ZR75.1 and MBA-MB-453). The parallel reaction monitoring targeted proteomic analysis further confirmed that altered protein expression (e.g. KLK3, and ALOX15B) in the supernatant and cell lysate of DHT-treated BT-474 cells, compared to control cells. Discussion: Collectively, our findings suggest that AR modulates the metabolism of BT-474 cells by affecting expression of a large number of genes and proteins. Based on further pathway analysis, we suggest that AR acts as a tumor suppressor in BT-474 cells.
Project description:Herceptin (trastuzumab) is a humanized monoclonal antibody targeted to the Her2 receptor tyrosine kinase. Despite a robust response rate to Herceptin-based therapies in Her2-positive patients, resistance frequently arises within one year of the initial response. To address the mechanism of Herceptin resistance, we selected clonal variants of Her2-positive BT474 human breast cancer cells (BT/HerR) that are highly resistant to the anti-proliferative effects of Herceptin in the presence of 0.2 uM or 1.0 uM Herceptin. Our original report on these cell lines demonstrated sustained PI3K/Akt signaling and sensitivity to PI3K inhibitors in BT/HerR cells in the presence of Herceptin, suggesting dysregulation of that pathway as an essential component of Herceptin-resistant proliferation. To address the mechanism by which BT/HerR cells and their PI3K/Akt signaling pathway became resistant to Herceptin, we analyzed gene expression profiles of two clones (BT/HerR1.0C and BT/HerR 1.0E) that were selected in 1.0 uM Herceptin and two clones (BT/HerR0.2D and BT/HerR 0.2J) that were selected in 0.2 uM Herceptin, in comparison to the Herceptin sensitive BT474 parent cells.
Project description:Proteomic analysis of breast cancer spheroids obtained from BT-474 cell line to characterize Trastuzumab resistance mechanism. Four conditions were examined: responder and non-responder spheroids before and after a 15-days treatment with Trastuzumab (RS_0, RS_15, nRS_0 and nRS_15).
Project description:Background: The addition of the anti-HER2 antibody pertuzumab to trastuzumab/chemotherapy treatment in HER2+ breast cancer significantly improves clinical outcome. Concomitantly, the drug-antibody conjugate T-DM1 (trastuzumab-emantasine) has demonstrated efficacy, at least equal, to the combination of trastuzumab/chemotherapy. Scientific, economic and health challenges emerge from the clinical use of these novel anti-HER2 antibodies, aimed to identify new resistance mechanisms and to select the target breast cancer population. Objectives: (1) To identify primary resistance mechanisms to anti-HER2 antibodies trastuzumab, pertuzumab, and to the combined trastuzumab/pertuzumab or pertuzumab/T-DM1 therapy, (2) To identify acquired resistance mechanisms to anti-HER2 antibodies trastuzumab, pertuzumab, and to the combined trastuzumab/pertuzumab or pertuzumab/T-DM1 therapy, (3) To develop new combinations of anti-HER2 antibodies with other targeted therapies.
Project description:Three human ER+ breast cancer cell lines--MCF-7, T47-D, BT-474--grown with or without estradiol (E2). Keywords: Cell Line Comparison
Project description:Herceptin (trastuzumab) is a humanized monoclonal antibody targeted to the Her2 receptor tyrosine kinase. Despite a robust response rate to Herceptin-based therapies in Her2-positive patients, resistance frequently arises within one year of the initial response. To address the mechanism of Herceptin resistance, we selected clonal variants of Her2-positive BT474 human breast cancer cells (BT/HerR) that are highly resistant to the anti-proliferative effects of Herceptin in the presence of 0.2 uM or 1.0 uM Herceptin. Our original report on these cell lines demonstrated sustained PI3K/Akt signaling and sensitivity to PI3K inhibitors in BT/HerR cells in the presence of Herceptin, suggesting dysregulation of that pathway as an essential component of Herceptin-resistant proliferation. To address the mechanism by which BT/HerR cells and their PI3K/Akt signaling pathway became resistant to Herceptin, we analyzed gene expression profiles of two clones (BT/HerR1.0C and BT/HerR 1.0E) that were selected in 1.0 uM Herceptin and two clones (BT/HerR0.2D and BT/HerR 0.2J) that were selected in 0.2 uM Herceptin, in comparison to the Herceptin sensitive BT474 parent cells. Total cellular RNAs were extracted from BT474 (control) and four BT/HerR subclones, two that were originally selected in 1.0 uM Herceptin and two that were originally selected in 0.2 uM Herceptin. Two RNA samples independently prepared from each clone were analyzed.
Project description:Background: Central nervous system (CNS) metastases represent a major problem in the treatment of HER2-positive breast cancer due to the disappointing efficacy of HER2-targeted therapies in the brain microenvironment. The antibody-drug conjugate ado-trastuzumab emtansine (T-DM1) has shown efficacy in trastuzumab-resistant systemic breast cancer. Here, we tested the hypothesis that T-DM1 could overcome trastuzumab resistance in preclinical models of brain metastases. Methods: We treated mice bearing BT474 or MDA-MB-361 tumors in the CNS (N=9-11 per group), or cancer cells grown in organotypic brain slice cultures with trastuzumab or T-DM1 at equivalent or equipotent doses. Using intravital imaging, molecular techniques and histological analysis we determined tumor growth, mouse survival, cancer cell apoptosis and proliferation, tumor drug distribution, and HER2 signaling. All statistical tests were two-sided. Results: T-DM1 significantly delayed the growth of HER2-positive breast cancer brain metastases compared to trastuzumab. These findings were consistent between HER2-driven and PI3K-driven tumors. The activity of T-DM1 resulted in a striking survival benefit (median survival for BT474 tumors: 28d for trastuzumab vs 112d for T-DM1, HR=6.2, 95% CI=6.1 to 85.84; P<.001). No difference in drug distribution and HER2-signaling was revealed between the two groups. However, T-DM1 led to a significant increase in tumor cell apoptosis (One-way ANOVA for ApopTag, p<.001), which was associated with mitotic catastrophe. Conclusions: T-DM1 can overcome resistance to trastuzumab therapy in HER2-driven and PI3K-driven breast cancer brain lesions due to the cytotoxicity of the DM1 component. Clinical investigation of T-DM1 for patients with CNS metastases from HER2-positive breast cancer is warranted. Comparison of trastuzumab (n=4) and TDM-1 (n=4) treated BT-474 human breast carcinoma cells growing in murine brain