Project description:The objective of this study was to profile the gene-regulatory heterogeneities of breast epithelial cells grown in an ECM-rich environment. The approach was to use stochastic profiling (Janes et al., Nat Methods 7(4):311-7 [2010]) to collect 10-cell pools of ECM-attached cells obtained by laser-capture microdissection and measure fluctuations in the 10-cell-averaged measurements to infer heterogeneous regulatory states.
Project description:Basal-like carcinoma is a subtype of breast cancer that is characterized by poor prognosis and high intratumor heterogeneity. Using a basal-like breast epithelial line, we have identified two anti-correlated gene-expression programs that arise among single extracellular matrix (ECM)-attached cells during organotypic 3D culture. The first program contains TGFBR3, a high-affinity receptor for transforming growth factor β (TGFβ) and other related ligands. The second program contains the JUND transcription factor together with the basal-like marker, KRT5. By disrupting the TGFBR3 and JUND programs individually, we reveal an important circuit for 3D morphogenesis that is wired together by four negative-feedback loops. Computational modeling of this circuit showed that it could exhibit damped, antiphase oscillations when excited with small impulses of TGFβ-like ligand. We directly visualize the circuit's spontaneous dynamics in organotypic cultures by using live-cell imaging with engineered pathway reporters. Importantly, we show that the essence of the JUND-TGFBR3 expression circuit holds true in early basal-like tumors that heterogeneously express KRT5. Correlated JUND-KRT5 expression depends critically on contact with stromal ECM and local expression of tenascin C. This work illustrates how complex tumor heterogeneities can be deconstructed into intrinsic single-cell expression circuits that are modulated by the microenvironment. Gene expression analysis of outer ECM-attached vs. inner cells of MCF10A-5E clones grown in organotypic 3D culture at day 6. Total RNA was isolated from ~50 outer ECM-attached cells and ~50 inner cells, each separately microdissected from 8 micron sections of MCF10A structures at day 6 of morphogenesis. Total RNA was amplified in quadruplicate, and hybridized to HumanRef-8 v2.0 Expression BeadChips (Illumina).
Project description:Basal-like carcinoma is a subtype of breast cancer that is characterized by poor prognosis and high intratumor heterogeneity. Using a basal-like breast epithelial line, we have identified two anti-correlated gene-expression programs that arise among single extracellular matrix (ECM)-attached cells during organotypic 3D culture. The first program contains TGFBR3, a high-affinity receptor for transforming growth factor β (TGFβ) and other related ligands. The second program contains the JUND transcription factor together with the basal-like marker, KRT5. By disrupting the TGFBR3 and JUND programs individually, we reveal an important circuit for 3D morphogenesis that is wired together by four negative-feedback loops. Computational modeling of this circuit showed that it could exhibit damped, antiphase oscillations when excited with small impulses of TGFβ-like ligand. We directly visualize the circuit's spontaneous dynamics in organotypic cultures by using live-cell imaging with engineered pathway reporters. Importantly, we show that the essence of the JUND-TGFBR3 expression circuit holds true in early basal-like tumors that heterogeneously express KRT5. Correlated JUND-KRT5 expression depends critically on contact with stromal ECM and local expression of tenascin C. This work illustrates how complex tumor heterogeneities can be deconstructed into intrinsic single-cell expression circuits that are modulated by the microenvironment. Gene expression analysis of outer ECM-attached vs. inner cells of MCF10A-5E clones grown in organotypic 3D culture at day 6.
Project description:Experimental approaches to define the relationship between gene expression and nuclear matrix attachment regions (MARs) have given contrasting and method-specific results. We have developed a next generation sequencing strategy to identify MARs across the human genome (MAR-Seq). The method is based on crosslinking chromatin to its nuclear matrix attachment sites to minimize changes during biochemical processing. We used this method to compare nuclear matrix organization in MCF-10A mammary epithelial-like cells and MDA-MB-231 breast cancer cells and evaluated the results in the context of global gene expression (array analysis) and positional enrichment of gene-regulatory histone modifications (ChIP-Seq). In the normal-like cells, nuclear matrix–attached DNA was enriched in expressed genes, while in the breast cancer cells, it was enriched in non-expressed genes. In both cell lines, the chromatin modifications that mark transcriptional activation or repression were appropriately associated with gene expression. Using this new MAR-Seq approach, we provide the first genome-wide characterization of nuclear matrix attachment in mammalian cells and reveal that the nuclear matrix–associated genome is highly cell-context dependent.
Project description:ErbB2 activation of MCF10A cells gives rise to a multiacinar phenotype that is incompletely penetrant. To identify candidate upstream regulators of the phenotype, an MCF10A-5E clone was subcloned to express chimeric receptors of human EGFR and rat Erbb2, and this B2B1 subclone was stochastically profiled (PMID: 20228812) after 24 hours of 3D culture with or without synthetic dimerization.
Project description:Experimental approaches to define the relationship between gene expression and nuclear matrix attachment regions (MARs) have given contrasting and method-specific results. We have developed a next generation sequencing strategy to identify MARs across the human genome (MAR-Seq). The method is based on crosslinking chromatin to its nuclear matrix attachment sites to minimize changes during biochemical processing. We used this method to compare nuclear matrix organization in MCF-10A mammary epithelial-like cells and MDA-MB-231 breast cancer cells and evaluated the results in the context of global gene expression (array analysis) and positional enrichment of gene-regulatory histone modifications (ChIP-Seq). In the normal-like cells, nuclear matrix–attached DNA was enriched in expressed genes, while in the breast cancer cells, it was enriched in non-expressed genes. In both cell lines, the chromatin modifications that mark transcriptional activation or repression were appropriately associated with gene expression. Using this new MAR-Seq approach, we provide the first genome-wide characterization of nuclear matrix attachment in mammalian cells and reveal that the nuclear matrix–associated genome is highly cell-context dependent.
Project description:Experimental approaches to define the relationship between gene expression and nuclear matrix attachment regions (MARs) have given contrasting and method-specific results. We have developed a next generation sequencing strategy to identify MARs across the human genome (MAR-Seq). The method is based on crosslinking chromatin to its nuclear matrix attachment sites to minimize changes during biochemical processing. We used this method to compare nuclear matrix organization in MCF-10A mammary epithelial-like cells and MDA-MB-231 breast cancer cells and evaluated the results in the context of global gene expression (array analysis) and positional enrichment of gene-regulatory histone modifications (ChIP-Seq). In the normal-like cells, nuclear matrix–attached DNA was enriched in expressed genes, while in the breast cancer cells, it was enriched in non-expressed genes. In both cell lines, the chromatin modifications that mark transcriptional activation or repression were appropriately associated with gene expression. Using this new MAR-Seq approach, we provide the first genome-wide characterization of nuclear matrix attachment in mammalian cells and reveal that the nuclear matrix–associated genome is highly cell-context dependent.
Project description:The fibroblast-populated 3D collagen matrix has been used to study the effect of mechanical stress on cell fate; this process is relevant to the fields of wound healing and tissue engineering. Gene array data was generated from mechanically stressed vs. stress-released matrices. The parameters of the collagen matrix model were: collagen type = bovine type I; collagen concentration = 1.5 mg/mL; initial matrix volume = 0.2 mL; initial matrix diameter = 11 mm (cultured in 24-well plates); cell type = human foreskin fibroblast, passage <10; initial matrix cell concentration = 1,000,000 cell/mL (200,000 cell/matrix); culture medium = 5% FBS in DMEM with 1 µg/mL ascorbate. Matrices (n = 6 per experimental group) were incubated for 24 hr in the attached state; the released groups then underwent matrix detachment from the culture plate (defined as t = 0), while the attached groups were left undisturbed. RNA was isolated from attached and released matrices 6 and 24 hr after t = 0. Gene expression in the attached vs. released condition at 6 or 24 hr then was analyzed by hybridizing the anti-sense RNA derived from attached and released matrices at a given time point onto a single chip.
Project description:The fibroblast-populated 3D collagen matrix has been used to study the effect of mechanical stress on cell fate; this process is relevant to the fields of wound healing and tissue engineering. Gene array data was generated from mechanically stressed vs. stress-released matrices. The parameters of the collagen matrix model were: collagen type = bovine type I; collagen concentration = 1.5 mg/mL; initial matrix volume = 0.2 mL; initial matrix diameter = 11 mm (cultured in 24-well plates); cell type = human foreskin fibroblast, passage <10; initial matrix cell concentration = 1,000,000 cell/mL (200,000 cell/matrix); culture medium = 5% FBS in DMEM with 1 M-BM-5g/mL ascorbate. Matrices (n = 6 per experimental group) were incubated for 24 hr in the attached state; the released groups then underwent matrix detachment from the culture plate (defined as t = 0), while the attached groups were left undisturbed. RNA was isolated from attached and released matrices 6 and 24 hr after t = 0. Gene expression in the attached vs. released condition at 6 or 24 hr then was analyzed by hybridizing the anti-sense RNA derived from attached and released matrices at a given time point onto a single chip. Refer to the attached Figure 1 for the experimental design. The index experiment was defined as the comparison of gene expression in attached vs. released collagen matrices in a single strain of human foreskin fibroblasts at 6 and 24 hr after stress-release (i.e., after t = 0). Each experiment utilized two mechanical conditions (attached and released) at two time points (6 and 24 hr). So with each condition utilizing 6 matrices, each index experiment required a total of 24 matrices. In each index experiment, the chip hybridizations were: (i) 6 hr attached vs. 6 hr released, and (ii) 24 hr attached vs. 24 hr released (i.e., two gene chips per index experiment). Each hybridization was done using a 10K spotted gene chip manufactured in the UNMC Microarray Core Facility. The index experiment was performed on three fibroblast strains, meaning that expressional data was derived from three foreskin donors (nonpooled samples). Dye-swap was not performed; dye assigned to attached vs. released remained constant among all chips. Since the index experiment was performed three times, the total number of gene chips used for this entire dataset was six.