Characteristics of Cross-Hybridization and Cross-Alignment in Pseudo-Xenograft samples by RNA-Seq and Microarrays [RNA-Seq]
ABSTRACT: In order to study molecular changes in the stroma from tissue samples it is recommended to separate tumor tissue from stromal tissue. This is particularly relevant to mouse tumor xenograft models where tumor, particularly metastatic tumors, can be small and difficult to separate from the host tissue. In our research we compared qualitatively the ability of high-throughput mRNA sequencing, RNA-Seq, and microarrays to detect tumor (human) and stromal (mouse) expression from mixed tumor-stromal samples in terms of the genes and pathways that are involved in cross-alignment (RNA-Seq) and cross-hybridization (microarrays). Human samples consisted of total RNA obtained from MDA-MB-231 human breast carcinoma cell line and isolated from three independent cultures of sub-confluent MDA-MB-231 cell lines in exponential phase of growth. Mouse samples were obtained from NOD scid gamma mice, and normal lung tissue was harvested from three independent age-matched mice.
Project description:Oct4, a key transcription factor for maintaining the pluripotency and self-renewal of stem cells has been reported previously. It also plays an important role in tumor proliferation and apoptosis, but the role of Oct4 been in tumor metastasis is still not very clear. Here, we found that ectopic expression of Oct4 in breast cancer cells can inhibit their migration and invasion. Detailed examinations revealed that Oct4 up-regulates expression of E-cadherin, indicative of its inhibitory role in epithelial-mesenchymal transition (EMT). RNA-sequence assay showed that Oct4 down-regulates expression of Rnd1. As an atypical Rho protein, Rnd1 can affect cytoskeleton rearrangement and regulate cadherin-based cell-cell adhesion by antagonizing the typical Rho protein, RhoA. Ectopic expression of Rnd1 in MDA-MB-231 cells changes cell morphology which influences cell adhesion and increases migration. It is reported that EMT is accompanied by cytoskeleton remodeling, we hypothesized that Rnd1 may play a role in regulating EMT. Over-expression of Rnd1 can partly rescue the inhibitory effects induced by Oct4, not only migration and invasion, but also in E-cadherin level and cellular morphology. Furthermore, silencing of Rnd1 can up-regulate the expression of E-cadherin in MDA-MB-231 cells. These results present evidence that ectopic expression of Oct4 increases E-cadherin and inhibits metastasis, effects which may be related to Rnd1 associated cell-cell adhesion in breast cancer cells. Examination of mRNA profiles in MDA-MB-231 cells with OCT4 overexpressing
Project description:Identifying the gene expression alterations that occur in both the tumor and stroma is essential to understanding tumor biology. We have developed a dual-species microarray analysis method that allows the dissection of both tumor and stromal gene expression profiles from xenograft models, based on limited interspecies cross-hybridization on Illumina gene expression beadchips. This methodology allows for simultaneous genome-wide analysis of gene expression profiles of both tumor cells and the associated stromal tissue. Data is provided regarding the crosshybridization of mouse liver RNA on human microarray, and MDA-MB-231 breast cancer cell line RNA on mouse microarray. Data is also provided for comparisons of MDA-MB-231 gene expression in vitro vs. in vivo, and mouse liver gene expression in control mice vs. stroma from MDA-MB-231 xenograft liver metastasis in tumor bearing mice A total of 18 samples were analyzed. Samples consist of 6 different types with each type in triplicate. Types are (1) MDA-MB-231 cell line grown in vitro and arrayed on mouse chips, (2) mouse liver from NOD/SCID mice arrayed on human chips, (3) MDA-MB-231 cell line grown in vitro arrayed on human chips, (4) MDA-MB-231 xenograft liver metastasis arrayed on human chips, (5) mouse liver from NOD/SCID mice arrayed on mouse chips, and (6) MDA-MB-231 xenograft liver metastasis arrayed on mouse chips. The overall design had three objectives: (1) to determine crosshybridizing probes based on sample types 1, 2, 3, and 5, (2) detect stromal and tumor expression using sample types 4 and 6, and (3) determine genes differentially expressed in tumor or metastasis compared to normal by comparing sample types 3 and 4 and comparing sample types 1 and 5.
Project description:Glucocorticoids (GC) have been widely used as coadjuvants in the treatment of solid tumors, but GC treatment may be associated with poor pharmacotherapeutic response and/or prognosis. The genomic action of GC in these tumors is largely unknown. Here we find that dexamethasone (Dex, a synthetic GC) regulated genes in triple-negative breast cancer (TNBC) cells are associated with drug resistance. Importantly, these GC-regulated genes are aberrantly expressed in TNBC patients and associated with unfavorable clinical outcomes. Interestingly, in TNBC cells, Compound A (CpdA, a selective GR modulator) only regulates a small number of genes not involved in carcinogenesis and therapy resistance. Mechanistic studies using a ChIP-exo approach reveal that Dex- but not CpdA-liganded glucocorticoid receptor (GR) binds to a single glucocorticoid response element (GRE), which drives the expression of pro-tumorigenic genes. Our data suggest that development of safe coadjuvant therapy should consider the distinct genomic function between Dex- and CpdA-liganded GR. To study GR-regulated genes and define GRE in human genome, RNA-seq and GR ChIP-exo are performed in MDA-MB-231 cells before/after dex and CpdA stimulation. Each experiment includes two replicates.
Project description:Mutant p53 proteins, resulting form frequent TP53 tumor suppressor missense mutations, possess gain-of-function activities and are among the most widespread and robust oncoproteins in human tumors. They are potentially important but understudied therapeutic targets. No studies to date have distinguished common, therapeutically relevant mutant p53 gain-of-function effects, from effects specific to different mutant variants and cell backgrounds. Here we identify 26S proteasome machinery as the common downstream effector controlled by mutant p53s in Triple Negative Breast Cancer (TNBC - aggressive carcinomas with TP53 as the most frequently mutated locus) and conserved in other human cancers. We have identified this pathway using a combination of single-model, multi-method vertical analysis (whole cell proteome, RNA sequencing an ChIP sequencing) and multi-cell line, horizontal analysis of transcriptiomes. We found that different missense mutant p53s regardless of the cell background transcriptionaly activate whole 26S proteasome machinery. Proteasome activity is significantly increased in p53 mutant versus wild-type or knockdown/null status - in cellular and mouse models as well as in human breast tumors. Increased proteasome activity leads to inhibition of tumor suppressive pathways. The control of mutant p53 over proteasome transcription and activity results in the increased resistance to proteasome inhibitors. By combining the mutant p53 targeting agents and proteasome inhibitor we were able to overcome the “bounce-back” proteasome inhibitor resistance mechanism in mutant p53 bearing TNBC cells and xenografts in vivo.
Project description:Communication and interaction between carcinoma associated fibroblast (CAF) cells and tumor epithelium cells plays a critical role in cancer initiation and progression. However, a mechanistic understanding of how CAFs communicate with tumor cells to promote their proliferation and invasion is far from complete. In this study, we employed a SILAC labeling based co-culture system coupled with mass spectrometry analysis to identify and quantify the early phospho-signaling transductions induced by the crosstalk between CAFs and tumor cells. We performed three-state SILAC labeling for MDA-MB-231 and 82T. 9 million light labeled 82-L cells were co-cultured with medium labeled MDA-MB-231-M cells for 30 minutes. 9 million heavy labeled 82T-H cells were individually cultured in heavy SILAC media with for 30 minutes. Both individually cultured and co-cultured cells were quickly harvested with 9 M urea lysis buffer and mixed together. Mixed lysates were sonicated, reduced, alkylated and digested by trypsin. Tryptic peptides were desalted using SepPak C18 cartridge and followed by phosphotyrosine peptide enrichment using immunoaffinity purification with pY100 antibody. The enriched phosphopeptides were analyzed using a reverse-phase liquid chromatography system interfaced with an LTQ-Orbitrap Velos mass spectrometer. The Proteome Discoverer (v2.0; Thermo Fisher Scientific) suite was used for quantitation and database searches. The tandem mass spectrometry data were searched using SEQUEST search algorithm against a Human RefSeq database supplemented with frequently observed contaminants. The probability of phosphorylation sites was determined from the PhosphoRS algorithm.
Project description:Maintenance of chromatin structure is essential to eukaryotic life; dysregulation is known to be causal for aberrant development and disease. The Mi-2/nucleosome remodeling and histone deacetylase (NuRD) complex is a multiprotein machine proposed to regulate chromatin structure by nucleosome remodeling and histone deacetylation activities. We identified the localization of MBD3, a component of Mi-2/NuRD complex, in two breast cancer cell lines (MCF7 and MDA-MB-231) using ChIP-Seq. MBD3 showed cell-type specific localization with overlap across cell lines being less than 50%. MBD3 localized across gene bodies, peaking around the transcription start site (TSS). Contrary to existing models, MBD3 preferentially associated with CpG rich promoters marked by H3K4me3. These data suggest that MBD3, and by extension the Mi-2/NuRD complex, may have roles in fine tuning expression for active genes. These data represent an important first step in defining regulatory mechanisms by which Mi-2/NuRD complex controls chromatin structure and gene expression. Identification of MBD3 localization in human breast cancer cell lines
Project description:The transcription factor GATA3 is essential for luminal cell differentiation during mammary gland development and critical for formation of the luminal subtypes of breast cancer. Ectopic expression of GATA3 promoted global alterations of the transcriptome of basal triple-negative breast cancer cells resulting in molecular and cellular changes associated with a more differentiated, luminal tumor subtype and a concomitant reduction in primary tumor growth, lung metastasis, and macrophage recruitment at the metastatic site. Importantly, we demonstrate that the inhibition of metastases by GATA3 results from the suppression of lysyl oxidase (LOX) expression, a metastasis promoting matrix protein that affects cell proliferation, cross-linking of extracellular collagen types, and establishment of the metastatic niche. There are 2 samples sent in triplicates.
Project description:RNA expression patterns of breast cell lines were compared with a breast cell line mixed reference. Gene expression profiles of 52 individual breast cell lines relative to a breast cell line reference mix containing equal amounts of 10 breast cell lines.
Project description:RNA was isolated from ectopically sFRP1-expressing MDA-MB-231 cells and control MDA-MB-231 cells and as well from tumor lysates arising from these cells as nude mouse xenograft. Gene expression profiles for these samples were investigated using Affymetrix arrays. Experiment Overall Design: MDA-MB-231 human breast cancer cells were stably transfected with human sFRP1 encoding vector or empty vector as control. After the selection with antibiotics, three clones of MDA-MB-231/sFRP1 and three clones of MDA-MB-231/control were selected. These six clones were cultured individually in DMEM 10% FCS with 1mg/ml G-418. When cells reached 70-80% confluence, RNA was isolated from the cells. In parallel, the three clones of MDA-MB-231/sFRP1 and the three clones of MDA-MB-231/control were pooled respectively. One million of cells from each pool were suspended in 100ul PBS and injected to fat pads of female balb/c nude mice (6 mice were injected with MDA-MB-231/sFRP1 and 5 mice were injected with MDA-MB-231/control) to do a xenograft experiment. A few - several weeks after, mice were sacrificed when tumor reached a certain size, tumors were taken and RNA was isolated using trizol reagent.
Project description:Small-molecule Smac mimetics target inhibitor of apoptosis (IAP) proteins to induce TNFα-dependent apoptosis in cancer cells and several Smac mimetics have been advanced into clinical development as a new class of anticancer drugs. However, preclinical studies have shown that only a small subset of cancer cell lines are sensitive to Smac mimetics used as single agents and these cell lines are at risk of developing drug resistance to Smac mimetics. Thus, it is important to understand the molecular mechanisms underlying intrinsic and acquired resistance of cancer cells to Smac mimetics in order to develop effective therapeutic strategies to overcome or prevent Smac mimetic resistance. We established Smac mimetic resistant sublines derived from MDA-MB-231 breast cancer cells, which exhibit exquisite sensitivity to the Smac mimetic SM-164, and used microarrays to detail the global programme of gene expression underlying SM-164 resistance in MDA-MB-231 cells and identified differentially expressed genes in SM-164-resistant and -sensitive MDA-MB-231 cells. SCID mice with MDA-MB-231 xenograft tumors were treated with 5 mg/kg of SM-164 intravenously for 5 days/week for 2 weeks. SM-164-regressed MDA-MB-231 tumors regrew after treatment ended. Tumor cells from these regrown MDA-MB-231 tumors were isolated and total RNAs were prepared for microarray analysis.