Project description:Dysregulated choline metabolism is a well-known feature of breast cancer, but the underlying mechanisms are not fully understood. In this study, the metabolomic and transcriptomic characteristics of a large panel of human breast cancer xenograft models were mapped, with focus on choline metabolism. Methods: Tumor specimens from 34 patient-derived xenograft models were collected and divided in two. One part was examined using high-resolution magic angle spinning (HR-MAS) MR spectroscopy while another part was analysed using gene expression microarrays. Expression data of genes encoding proteins in the choline metabolism pathway were analysed and correlated to the levels of choline (Cho), phosphocholine (PCho) and glycerophosphocholine (GPC) using Pearson’s correlation analysis. For comparison purposes, metabolic and gene expression data were collected from human breast tumors belonging to corresponding molecular subgroups. Results: Most of the xenograft models were classified as basal-like (N=19) or luminal B (N=7). These two subgroups showed significantly different choline metabolic and gene expression profiles. The luminal B xenografts were characterized by a high PCho/GPC ratio while the basal-like xenografts were characterized by highly variable PCho/GPC ratio. Also, Cho, PCho and GPC levels were correlated to expression of several genes encoding proteins in the choline metabolism pathway, including choline kinase alpha (CHKA) and glycerophosphodiester phosphodiesterase domain containing 5 (GDPD5). These characteristics were similar to those found in human tumor samples. Discussion: The higher PCho/GPC ratio found in luminal B compared with most basal-like breast cancer xenograft models and human tissue samples do not correspond to results observed from in vitro studies. It is likely that microenvironmental factors play a role in the in vivo regulation of choline metabolism. Cho, PCho and GPC were correlated to different choline pathway-encoding genes in luminal B compared with basal-like xenografts, suggesting that regulation of choline metabolism may vary between different breast cancer subgroups. The concordance between the metabolic and gene expression profiles from xenograft models with breast cancer tissue samples from patients indicates that these xenografts are representative models of human breast cancer and represent relevant models to study tumor metabolism in vivo. Gene expression was measured in 30 human breast cancer xenografts, one sample from each model
Project description:Choline (reference 1) and glucose (reference 2) was studied using HR MAS MR spectroscopy data and 105 and 38 gene transcripts were selected respectively from the microarray data to study differences between two xenograft models. Reference 1: Moestue SA et al, Distinct choline metabolic profiles are associated with differences in gene expression for basal-like and luminal-like breast cancer xenograft models, BMC Cancer 2010 Aug 17;10:433 (PMID: 20716336). Reference 2: Grinde et al., submitted The microarray data from the luminal-like and basal-like xenograft models were compared for selected genes, using Limma Bioconducotr package
Project description:Dysregulated choline metabolism is a well-known feature of breast cancer, but the underlying mechanisms are not fully understood. In this study, the metabolomic and transcriptomic characteristics of a large panel of human breast cancer xenograft models were mapped, with focus on choline metabolism. Methods: Tumor specimens from 34 patient-derived xenograft models were collected and divided in two. One part was examined using high-resolution magic angle spinning (HR-MAS) MR spectroscopy while another part was analysed using gene expression microarrays. Expression data of genes encoding proteins in the choline metabolism pathway were analysed and correlated to the levels of choline (Cho), phosphocholine (PCho) and glycerophosphocholine (GPC) using Pearson’s correlation analysis. For comparison purposes, metabolic and gene expression data were collected from human breast tumors belonging to corresponding molecular subgroups. Results: Most of the xenograft models were classified as basal-like (N=19) or luminal B (N=7). These two subgroups showed significantly different choline metabolic and gene expression profiles. The luminal B xenografts were characterized by a high PCho/GPC ratio while the basal-like xenografts were characterized by highly variable PCho/GPC ratio. Also, Cho, PCho and GPC levels were correlated to expression of several genes encoding proteins in the choline metabolism pathway, including choline kinase alpha (CHKA) and glycerophosphodiester phosphodiesterase domain containing 5 (GDPD5). These characteristics were similar to those found in human tumor samples. Discussion: The higher PCho/GPC ratio found in luminal B compared with most basal-like breast cancer xenograft models and human tissue samples do not correspond to results observed from in vitro studies. It is likely that microenvironmental factors play a role in the in vivo regulation of choline metabolism. Cho, PCho and GPC were correlated to different choline pathway-encoding genes in luminal B compared with basal-like xenografts, suggesting that regulation of choline metabolism may vary between different breast cancer subgroups. The concordance between the metabolic and gene expression profiles from xenograft models with breast cancer tissue samples from patients indicates that these xenografts are representative models of human breast cancer and represent relevant models to study tumor metabolism in vivo.
Project description:The study of breast cancer pathogenesis relies heavily on the use of established cell lines often derived from metastatic lesions, which while having significantly contributed to the knowledge of breast cancer biology may inadvertently limit the understanding of the mechanisms governing the metastatic process. Our goal was to establish primary cultures from dissociation of breast tumors in order to provide cellular models that may better recapitulate breast cancer pathogenesis and the metastatic process. These cellular models differ from recently developed patient derived xenograft models (PDX) in that they can be used for both in vitro and in vivo studies. Here we report the characterization of six cellular models derived from the dissociation of primary breast tumor specimens, referred to as “dissociated tumor (DT) cells”. Among the DT cells are those that are tumorigenic and metastatic in immunosuppressed mice, and a group of cancer-associated fibroblasts (CAFs). In vitro, DT cells were characterized by proliferation assays, colony formation assays, protein and gene expression profiling, including PAM50 predictor analysis. The latter showed DT cultures similar to their paired primary tumor and as belonging to the basal and Her2-enriched subtypes, offering novel cellular models of these ER-negative breast cancer subtypes. In vivo, three DT cultures are tumorigenic in NOD/SCID and NSG mice, and one of these is metastatic to lymph nodes and lung after orthotopic inoculation into the mammary fat pad, without excision of the primary tumor. DT cultures comprised of CAFs were isolated from luminal-A, Her2-enriched and basal primary tumors, providing subtype-specific components of the tumor microenvironment. Altogether, these DT cultures provide closer-to-primary cellular models for the study of breast cancer pathogenesis, metastasis and tumor microenvironment. reference x sample
Project description:GATA3 transcription factor is considered critical for luminal development and differentiation in normal and malignant mammary epithelial cells (MECs). The androgen receptor (AR) has also been associated with luminal gene expression profiles in breast cancer, independent of the estrogen receptor (ER), and has been shown to promote a basal to luminal phenotype transition in mouse MECs. To date, the potential interaction of GATA3 and AR in transcriptional regulation of lineage driver genes in breast cancer has never been investigated. Our unbiased proteomic analysis identified GATA3 as a novel AR interacting protein in a variety of breast cancer cell types regardless of ER expression. We showed that AR and GATA3 interact in the cytoplasm and nucleus of normal and malignant breast epithelia, an interaction increased by androgen treatment. Androgen stimulation of breast cancer cells also induced nuclear translocation of AR and GATA3 and resulted in enrichment of co-localized AR and GATA3 chromatin binding events. Using ER+ and/or ER- breast cancer cell lines and ER+ patient-derived xenograft (PDX) models of breast cancer, we identified a conserved subset of AR agonist-induced AR and GATA3 co-occupied cis-regulatory elements across all models. Knockdown experiments indicated that GATA3 acts as an AR co-regulator to upregulate transcription of known luminal-lineage genes (e.g. EHF, AQP3, and KDM4B) and downregulate basal-lineage genes (e.g. SMAD3 and ELK3). Also, we showed an induction in the chromatin accessibility at those subsets of common AR-GATA3 cis-regulatory elements, which drive the luminal lineage identity in breast cancer upon androgen stimulation. Collectively, AR-GATA3 interaction and function provide a mechanism underpinning epithelial breast cancer cells that are classified as having a luminal mature transcriptome independent of ER status, through regulating the expression of lineage-restricted markers.
Project description:GATA3 transcription factor is considered critical for luminal development and differentiation in normal and malignant mammary epithelial cells (MECs). The androgen receptor (AR) has also been associated with luminal gene expression profiles in breast cancer, independent of the estrogen receptor (ER), and has been shown to promote a basal to luminal phenotype transition in mouse MECs. To date, the potential interaction of GATA3 and AR in transcriptional regulation of lineage driver genes in breast cancer has never been investigated. Our unbiased proteomic analysis identified GATA3 as a novel AR interacting protein in a variety of breast cancer cell types regardless of ER expression. We showed that AR and GATA3 interact in the cytoplasm and nucleus of normal and malignant breast epithelia, an interaction increased by androgen treatment. Androgen stimulation of breast cancer cells also induced nuclear translocation of AR and GATA3 and resulted in enrichment of co-localized AR and GATA3 chromatin binding events. Using ER+ and/or ER- breast cancer cell lines and ER+ patient-derived xenograft (PDX) models of breast cancer, we identified a conserved subset of AR agonist-induced AR and GATA3 co-occupied cis-regulatory elements across all models. Knockdown experiments indicated that GATA3 acts as an AR co-regulator to upregulate transcription of known luminal-lineage genes (e.g. EHF, AQP3, and KDM4B) and downregulate basal-lineage genes (e.g. SMAD3 and ELK3). Also, we showed an induction in the chromatin accessibility at those subsets of common AR-GATA3 cis-regulatory elements, which drive the luminal lineage identity in breast cancer upon androgen stimulation. Collectively, AR-GATA3 interaction and function provide a mechanism underpinning epithelial breast cancer cells that are classified as having a luminal mature transcriptome independent of ER status, through regulating the expression of lineage-restricted markers.
Project description:GATA3 transcription factor is considered critical for luminal development and differentiation in normal and malignant mammary epithelial cells (MECs). The androgen receptor (AR) has also been associated with luminal gene expression profiles in breast cancer, independent of the estrogen receptor (ER), and has been shown to promote a basal to luminal phenotype transition in mouse MECs. To date, the potential interaction of GATA3 and AR in transcriptional regulation of lineage driver genes in breast cancer has never been investigated. Our unbiased proteomic analysis identified GATA3 as a novel AR interacting protein in a variety of breast cancer cell types regardless of ER expression. We showed that AR and GATA3 interact in the cytoplasm and nucleus of normal and malignant breast epithelia, an interaction increased by androgen treatment. Androgen stimulation of breast cancer cells also induced nuclear translocation of AR and GATA3 and resulted in enrichment of co-localized AR and GATA3 chromatin binding events. Using ER+ and/or ER- breast cancer cell lines and ER+ patient-derived xenograft (PDX) models of breast cancer, we identified a conserved subset of AR agonist-induced AR and GATA3 co-occupied cis-regulatory elements across all models. Knockdown experiments indicated that GATA3 acts as an AR co-regulator to upregulate transcription of known luminal-lineage genes (e.g. EHF, AQP3, and KDM4B) and downregulate basal-lineage genes (e.g. SMAD3 and ELK3). Also, we showed an induction in the chromatin accessibility at those subsets of common AR-GATA3 cis-regulatory elements, which drive the luminal lineage identity in breast cancer upon androgen stimulation. Collectively, AR-GATA3 interaction and function provide a mechanism underpinning epithelial breast cancer cells that are classified as having a luminal mature transcriptome independent of ER status, through regulating the expression of lineage-restricted markers.
Project description:Acquired resistance to endocrine therapy occurs with high frequency in patients with luminal breast cancer (LBC). We report here the establishment of four patient-derived xenograft models of LBC with acquired resistance in vivo to tamoxifen and estrogen deprivation.
Project description:Choline (reference 1) and glucose (reference 2) was studied using HR MAS MR spectroscopy data and 105 and 38 gene transcripts were selected respectively from the microarray data to study differences between two xenograft models. Reference 1: Moestue SA et al, Distinct choline metabolic profiles are associated with differences in gene expression for basal-like and luminal-like breast cancer xenograft models, BMC Cancer 2010 Aug 17;10:433 (PMID: 20716336). Reference 2: Grinde et al., NMR Biomed. 2011 Dec;24(10):1243-52. doi: 10.1002/nbm.1683. (PMID: 21462378)