38 Matching Results

Search Results

Advanced search parameters have been applied.

Targeting the tumor microenvironment

Description: Despite some notable successes cancer remains, for the most part, a seemingly intractable problem. There is, however, a growing appreciation that targeting the tumor epithelium in isolation is not sufficient as there is an intricate mutually sustaining synergy between the tumor epithelial cells and their surrounding stroma. As the details of this dialogue emerge, new therapeutic targets have been proposed. The FDA has already approved drugs targeting microenvironmental components such as VEGF and aromatase and many more agents are in the pipeline. In this article, we describe some of the 'druggable' targets and processes within the tumor microenvironment and review the approaches being taken to disrupt these interactions.
Date: November 7, 2006
Creator: Kenny, P.A.; Lee, G.Y. & Bissell, M.J.
Partner: UNT Libraries Government Documents Department

Matrix Metalloproteinase Stromelysin-1 Triggers a Cascade of Molecular Alterations that leads to stable epithelial-to-Mesenchymal Conversion and a Premalignant Phenotype in Mammary Epithelial Cells

Description: Matrix metalloproteinases (MMPs) regulate ductal morphogenesis, apoptosis, and neoplastic progression in mammary epithelial cells. To elucidate the direct effects of MMPs on mammary epithelium, we generated functionally normal cells expressing an inducible autoactivating stromelysin-1 (SL-1) transgene. Induction of SL-1 expression resulted in cleavage of E-cadherin, and triggered progressive phenotypic conversion characterized by disappearance of E-cadherin and catenins from cell-cell contacts, downregulation of cytokeratins, upregulation of vimentin, induction of keratinocyte growth factor expression and activation, and upregulation of endogenous MMPs. Cells expressing SL-1 were unable to undergo lactogenic differentiation and became invasive. Once initiated, this phenotypic conversion was essentially stable, and progressed even in the absence of continued SL-1 expression. These observations demonstrate that inappropriate expression of SL-1 initiates a cascade of events that may represent a coordinated program leading to loss of the differentiated epithelial phenotype and gain of some characteristics of tumor cells. Our data provide novel insights into how MMPs function in development and neoplastic conversion.
Date: August 11, 1997
Creator: Lochter, A.; Galosy, S.; Muschler, J.; Freedman, N.; Werb, Z. & Bissell, M.J.
Partner: UNT Libraries Government Documents Department

Laminin Mediates Tissue-specific Gene Expression in Mammary Epithelia

Description: Tissue-specific gene expression in mammary epithelium is dependent on the extracellular matrix as well as hormones. There is good evidence that the basement membrane provides signals for regulating beta-casein expression, and that integrins are involved in this process. Here, we demonstrate that in the presence of lactogenic hormones, laminin can direct expression of the beta-casein gene. Mouse mammary epithelial cells plated on gels of native laminin or laminin-entactin undergo functional differentiation. On tissue culture plastic, mammary cells respond to soluble basement membrane or purified laminin, but not other extracellular matrix components, by synthesizing beta-casein. In mammary cells transfected with chloramphenicol acetyl transferase reporter constructs, laminin activates transcription from the beta-casein promoter through a specific enhancer element. The inductive effect of laminin on casein expression was specifically blocked by the E3 fragment of the carboxy terminal region of the alpha 1 chain of laminin, by antisera raised against the E3 fragment, and by a peptide corresponding to a sequence within this region. Our results demonstrate that laminin can direct tissue-specific gene expression in epithelial cells through its globular domain.
Date: April 1, 1995
Creator: Streuli, Charles H; Schmidhauser, Christian; Bailey, Nina; Yurchenco, Peter; Skubitz, Amy P. N.; Roskelley, Calvin et al.
Partner: UNT Libraries Government Documents Department

Normal and tumor-derived myoepithelial cells differ in their ability to interact with luminal breast epithelial cells for polarity and basement membrane deposition

Description: The signals that determine the correct polarity of breast epithelial structures in vivo are not understood. We have shown previously that luminal epithelial cells can be polarized when cultured within a reconstituted basement membrane gel. We reasoned that such cues in vivo may be given by myoepithelial cells. Accordingly, we used an assay where luminal epithelial cells are incorrectly polarized to test this hypothesis. We show that culturing human primary luminal epithelial cells within collagen-I gels leads to formation of structures with no lumina and with reverse polarity as judged by dual stainings for sialomucin, epithelial specific antigen or occludin. No basement membrane is deposited, and {beta}4-integrin staining is negative. Addition of purified human myoepithelial cells isolated from normal glands corrects the inverse polarity, and leads to formation of double-layered acini with central lumina. Among the laminins present in the human breast basement membrane (laminin-1, -5 and -10/11), laminin-1 was unique in its ability to substitute for myoepithelial cells in polarity reversal. Myoepithelial cells were purified also from four different breast cancer sources including a biphasic cell line. Three out of four samples either totally lacked the ability to interact with luminal epithelial cells, or conveyed only correction of polarity in a fraction of acini. This behavior was directly related to the ability of the tumor myoepithelial cells to produce {alpha}-1 chain of laminin. In vivo, breast carcinomas were either negative for laminin-1 (7/12 biopsies) or showed a focal, fragmented deposition of a less intensely stained basement membrane (5/12 biopsies). Dual staining with myoepithelial markers revealed that tumorassociated myoepithelial cells were either negative or weakly positive for expression of laminin-1, establishing a strong correlation between loss of laminin-1 and breast cancer. We conclude that the double-layered breast acinus may be recapitulated in culture and that one reason for the ability ...
Date: October 4, 2001
Creator: Gudjonsson, Thorarinn; Ronnov-Jessen, Lone; Villadsen, Rene; Rank, Fritz; Bissell, Mina J. & Petersen, Ole William
Partner: UNT Libraries Government Documents Department

Endothelial Cell Migration and Vascular Endothelial Growth Factor Expression Are the Result of Loss of Breast Tissue Polarity

Description: Recruiting a new blood supply is a rate-limiting step in tumor progression. In a three-dimensional model of breast carcinogenesis, disorganized, proliferative transformed breast epithelial cells express significantly higher expression of angiogenic genes compared with their polarized, growth-arrested nonmalignant counterparts. Elevated vascular endothelial growth factor (VEGF) secretion by malignant cells enhanced recruitment of endothelial cells (EC) in heterotypic cocultures. Significantly, phenotypic reversion of malignant cells via reexpression of HoxD10, which is lost in malignant progression, significantly attenuated VEGF expression in a hypoxia-inducible factor 1{alpha}-independent fashion and reduced EC migration. This was due primarily to restoring polarity: forced proliferation of polarized, nonmalignant cells did not induce VEGF expression and EC recruitment, whereas disrupting the architecture of growth-arrested, reverted cells did. These data show that disrupting cytostructure activates the angiogenic switch even in the absence of proliferation and/or hypoxia and restoring organization of malignant clusters reduces VEGF expression and EC activation to levels found in quiescent nonmalignant epithelium. These data confirm the importance of tissue architecture and polarity in malignant progression.
Date: May 26, 2009
Creator: Chen, Amy; Cuevas, Ileana; Kenny, Paraic A; Miyake, Hiroshi; Mace, Kimberley; Ghajar, Cyrus et al.
Partner: UNT Libraries Government Documents Department

The MAPKERK-1,2 pathway integrates distinct and antagonistic signals from TGF alpha and FGF7 in morphogenesis of mouse mammary epithelium

Description: Transforming growth factor-{alpha} (TGF{alpha}) and fibroblast growth factor-7 (FGF7) exhibit distinct expression patterns in the mammary gland. Both factors signal through mitogen-activated kinase/extracellular regulated kinase-1,2 (MAPK{sup ERK1,2}); however, their unique and/or combined contributions to mammary morphogenesis have not been examined. In ex vivo mammary explants, we show that a sustained activation of MAPK{sup ERK1,2} for 1 h, induced by TGF{alpha}, was necessary and sufficient to initiate branching morphogenesis, whereas a transient activation (15 min) of MAPK{sup ERK1,2}, induced by FGF7, led to growth without branching. Unlike TGF{alpha}, FGF7 promoted sustained proliferation as well as ectopic localization of, and increase in, keratin-6 expressing cells. The response of the explants to FGF10 was similar to that to FGF7. Simultaneous stimulation by FGF7 and TGF{alpha} indicated that the FGF7-induced MAPK{sup ERK1,2} signaling and associated phenotypes were dominant: FGF7 may prevent branching by suppression of two necessary TGF{alpha}-induced morphogenetic effectors, matrix metalloproteinase-3 (MMP-3/stromelysin-1), and fibronectin. Our findings indicate that expression of morphogenetic effectors, proliferation, and cell-type decisions during mammary organoid morphogenesis are intimately dependent on the duration of activation of MAPK{sup ERK1,2} activation.
Date: October 3, 2006
Creator: Fata, Jimmie E; Mori, Hidetoshi; Ewald, Andrew J; Zhang, Hui; Yao, Evelyn; Werb, Zena et al.
Partner: UNT Libraries Government Documents Department

Molecular cytogenetic characterization of a human thyroid cancercell line

Description: The incidence of papillary thyroid carcinoma (PTC) increases significantly after exposure of the head and neck region to ionizing radiation, yet we know neither the steps involved in malignant transformation of thyroid epithelium nor the specific carcinogenic mode of action of radiation. Such increased tumor frequency became most evident in children after the 1986 nuclear accident in Chernobyl, Ukraine. In the twelve years following the accident, the average incidence of childhood PTCs (chPTC) increased over one hundred-fold compared to the rate of about 1 tumor incidence per 10{sup 6} children per year prior to 1986. To study the etiology of radiation-induced thyroid cancer, we formed an international consortium to investigate chromosomal changes and altered gene expression in cases of post-Chernobyl chPTC. Our approach is based on karyotyping of primary cultures established from chPTC specimens, establishment of cell lines and studies of genotype-phenotype relationships through high resolution chromosome analysis, DNA/cDNA micro-array studies, and mouse xenografts that test for tumorigenicity. Here, we report the application of fluorescence in situ hybridization (FISH)-based techniques for the molecular cytogenetic characterization of a highly tumorigenic chPTC cell line, S48TK, and its subclones. Using chromosome 9 rearrangements as an example, we describe a new approach termed ''BAC-FISH'' to rapidly delineate chromosomal breakpoints, an important step towards a better understanding of the formation of translocations and their functional consequences.
Date: January 4, 2006
Creator: Weier, Heinz-Ulrich G.; Tuton, Tiffany B.; Ito, Yuko; Chu, LisaW.; Lu, Chung-Mei; Baumgartner, Adolf et al.
Partner: UNT Libraries Government Documents Department

Energy deposition and radiation quality of radon and radon daughters. Final report

Description: This program was aimed at creating a quantitative physical description, at the micrometer and nanometer levels, of the physical interactions of the alpha particles from radon and its daughters with cells at risk in the bronchial epithelium. The authors calculated alpha-particle energy spectra incident upon the cells and also energy deposition spectra in micrometer- and nanometer-sized sites as a function of cell depth, site size, airway diameter, activities of {sup 218}Po and {sup 214}Po, and other parameters. These data are now being applied, using biophysical models of radiation effects, to predict cell killing, mutations, and cell transformation. The model predictions are then compared to experimental biophysical, biochemical, and biological information. These studies contribute to a detailed understanding of the mechanisms of the biological effectiveness of the radiations emitted by radon and its progeny.
Date: September 9, 1996
Creator: Karam, L.R. & Caswell, R.S.
Partner: UNT Libraries Government Documents Department

Inhibiting Vimentin or beta 1-integrin Reverts Prostate Tumor Cells in IrECM and Reduces Tumor Growth

Description: Prostate epithelial cells grown embedded in laminin-rich extracellular matrix (lrECM) undergo morphological changes that closely resemble their architecture in vivo. In this study, growth characteristics of three human prostate epithelial sublines derived from the same cellular lineage, but displaying different tumorigenic and metastatic properties in vivo, were assessed in three-dimensional (3D) lrECM gels. M12, a highly tumorigenic and metastatic subline, was derived from the parental prostate epithelial P69 cell line by selection in nude mice and found to contain a deletion of 19p-q13.1. The stable reintroduction of an intact human chromosome 19 into M12 resulted in a poorly tumorigenic subline, designated F6. When embedded in lrECM gels, the nontumorigenic P69 line produced acini with clearly defined lumena. Immunostaining with antibodies to {beta}-catenin, E-cadherin or {alpha}6-, {beta}4- and {beta}1-integrins showed polarization typical of glandular epithelium. In contrast, the metastatic M12 subline produced highly disorganized cells with no evidence of polarization. The F6 subline reverted to acini-like structures exhibiting basal polarity marked with integrins. Reducing either vimentin levels via siRNA interference or {beta}1-integrin expression by the addition of the blocking antibody, AIIB2, reorganized the M12 subline into forming polarized acini. The loss of vimentin significantly reduced M12-Vim tumor growth when assessed by subcutaneous injection in athymic mice. Thus, tumorigenicity in vivo correlated with disorganized growth in 3D lrECM gels. These studies suggest that the levels of vimentin and {beta}1-integrin play a key role in the homeostasis of the normal acini in prostate and that their dysregulation may lead to tumorigenesis.
Date: July 27, 2009
Creator: Zhang, Xueping; Fournier, Marcia V.; Ware, Joy L.; Bissell, Mina J. & Zehner, Zendra E.
Partner: UNT Libraries Government Documents Department

Inhibition of vimentin or B1 integrin reverts morphology of prostate tumor cells grown in laminin-rich extracellular matrix gels and reduces tumor growth in vivo

Description: Prostate epithelial cells grown embedded in laminin-rich extracellular matrix (lrECM) undergo morphologic changes that closely resemble their architecture in vivo. In this study, growth characteristics of three human prostate epithelial sublines derived from the same cellular lineage, but displaying different tumorigenic and metastatic properties in vivo, were assessed in three-dimensional lrECM gels. M12, a highly tumorigenic and metastatic subline, was derived from the immortalized, prostate epithelial P69 cell line by selection in athymic, nude mice and found to contain a deletion of 19p-q13.1. The stable reintroduction of an intact human chromosome 19 into M12 resulted in a poorly tumorigenic subline, designated F6. When embedded in lrECM gels, the parental, nontumorigenic P69 line produced acini with clearly defined lumena. Immunostaining with antibodies to {beta}-catenin, E-cadherin, or {alpha}6 and {beta}1 integrins showed polarization typical of glandular epithelium. In contrast, the metastatic M12 subline produced highly disorganized cells with no evidence of polarization. The F6 subline reverted to acini-like structures exhibiting basal polarity marked with integrins. Reducing either vimentin levels via small interfering RNA interference or the expression of {alpha}6 and {beta}1 integrins by the addition of blocking antibodies, reorganized the M12 subline into forming polarized acini. The loss of vimentin significantly reduced M12-Vim tumor growth when assessed by s.c. injection in athymic mice. Thus, tumorigenicity in vivo correlated with disorganized growth in three-dimensional lrECM gels. These studies suggest that the levels of vimentin and {beta}1 integrin play a key role in the homeostasis of the normal acinus in prostate and that their dysregulation may lead to tumorigenesis. [Mol Cancer Ther 2009;8(3):499-508].
Date: June 12, 2008
Creator: Zhang, Xueping; Fournier, Marcia V; Ware, Joy L; Bissell, Mina J; Yacoub, Adly & Zehner, Zendra E
Partner: UNT Libraries Government Documents Department

New insights into potential functions for the protein 4.1superfamily of proteins in kidney epithelium

Description: Members of the protein 4.1 family of adapter proteins are expressed in a broad panel of tissues including various epithelia where they likely play an important role in maintenance of cell architecture and polarity and in control of cell proliferation. We have recently characterized the structure and distribution of three members of the protein 4.1 family, 4.1B, 4.1R and 4.1N, in mouse kidney. We describe here binding partners for renal 4.1 proteins, identified through the screening of a rat kidney yeast two-hybrid system cDNA library. The identification of putative protein 4.1-based complexes enables us to envision potential functions for 4.1 proteins in kidney: organization of signaling complexes, response to osmotic stress, protein trafficking, and control of cell proliferation. We discuss the relevance of these protein 4.1-based interactions in kidney physio-pathology in the context of their previously identified functions in other cells and tissues. Specifically, we will focus on renal 4.1 protein interactions with beta amyloid precursor protein (beta-APP), 14-3-3 proteins, and the cell swelling-activated chloride channel pICln. We also discuss the functional relevance of another member of the protein 4.1 superfamily, ezrin, in kidney physiopathology.
Date: June 17, 2005
Creator: Calinisan, Venice; Gravem, Dana; Chen, Ray Ping-Hsu; Brittin,Sachi; Mohandas, Narla; Lecomte, Marie-Christine et al.
Partner: UNT Libraries Government Documents Department

Nuclear substructure reorganization during late stageerythropoiesis is selective and does not involve caspase cleavage ofmajor nuclear substructural proteins

Description: Enucleation, a rare feature of mammalian differentiation, occurs in three cell types: erythroblasts, lens epithelium and keratinocytes. Previous investigations suggest that caspase activation functions in lens epithelial and keratinocyte enucleation, as well as in early erythropoiesis encompassing BFU-E differentiation to proerythroblast. To determine whether caspase activation contributes to later erythropoiesis and whether nuclear substructures other than chromatin reorganize, we analyzed distributions of nuclear subcompartment proteins and assayed for caspase-induced cleavage of subcompartmental target proteins in mouse erythroblasts. We found that patterns of lamin B in the filamentous network interacting with both the nuclear envelope and DNA, nuclear matrix protein NuMA, and splicing factors Sm and SC35 persisted during nuclear condensation, consistent with effective transcription of genes expressed late in differentiation. Thus nuclear reorganization prior to enucleation is selective, allowing maintenance of critical transcriptional processes independent of extensive chromosomal reorganization. Consistent with these data, we found no evidence for caspase-induced cleavage of major nuclear subcompartment proteins during late erythropoiesis, in contrast to what has been observed in early erythropoiesis and in lens epithelial and keratinocyte differentiation. These findings imply that nuclear condensation and extrusion during terminal erythroid differentiation involve novel mechanisms that do not entail major activation of apoptotic machinery.
Date: April 6, 2005
Creator: Krauss, Sharon Wald; Lo, Annie J.; Short, Sarah A.; Koury, MarkJ.; Mohandas, Narla & Chasis, Joel Anne
Partner: UNT Libraries Government Documents Department

A tool for the quantitative spatial analysis of mammary gland epithelium

Description: In this paper we present a method for the spatial analysis of complex cellular systems based on a multiscale study of neighborhood relationships. A function to measure those relationships, M, is introduced. The refined Relative Neighborhood Graph is then presented as a method to establish vicinity relationships within layered cellular structures, and particularized to epithelial cell nuclei in the mammary gland. Finally, the method is illustrated with two examples that show interactions within one population of epithelial cells and between two different populations.
Date: April 9, 2004
Creator: Ortiz de Solorzano, Carlos & Fernandez-Gonzalez, Rodrigo
Partner: UNT Libraries Government Documents Department

Persistence of gamma-H2AX and 53BP1 foci in proliferating and nonproliferating human mammary epithelial cells after exposure to gamma-rays or iron ions

Description: To investigate {gamma}-H2AX (phosphorylated histone H2AX) and 53BP1 (tumour protein 53 binding protein No. 1) foci formation and removal in proliferating and non-proliferating human mammary epithelial cells (HMEC) after exposure to sparsely and densely ionizing radiation under different cell culture conditions. HMEC cells were grown either as monolayers (2D) or in extracellular matrix to allow the formation of acinar structures in vitro (3D). Foci numbers were quantified by image analysis at various time points after exposure. Our results reveal that in non-proliferating cells under 2D and 3D cell culture conditions, iron-ion induced {gamma}-H2AX foci were still present at 72 h after exposure, although 53BP1 foci returned to control levels at 48 h. In contrast in proliferating HMEC, both {gamma}-H2AX and 53BP1 foci decreased to control levels during the 24-48 h time interval after irradiation under 2D conditions. Foci numbers decreased faster after {gamma}-ray irradiation and returned to control levels by 12 h regardless of marker, cell proliferation status, and cell culture condition. Conclusions: The disappearance of radiation induced {gamma}-H2AX and 53BP1 foci in HMEC have different dynamics that depend on radiation quality and proliferation status. Notably, the general patterns do not depend on the cell culture condition (2D versus 3D). We speculate that the persistent {gamma}-H2AX foci in iron-ion irradiated non-proliferating cells could be due to limited availability of double strand break (DSB) repair pathways in G0/G1-phase, or that repair of complex DSB requires replication or chromatin remodeling.
Date: December 22, 2010
Creator: Groesser, Torsten; Chang, Hang; Fontenay, Gerald; Chen, James; Costes, Sylvain V.; Barcellos-Hoff, Mary Helen et al.
Partner: UNT Libraries Government Documents Department

Quis custodiet ipsos custodies: who watches the watchmen?

Description: Should this be said again? No cell is an island and in tissue-specificity and cancer, context is supreme. Decades ago, seminal recombination experiments illustrated the dominant role of mammary mesenchyme in directing epithelial development, and strongly suggested that the microenvironment plays a significant role also in the manifestation of carcinoma. More direct evidence for such functions came from a study demonstrating that an unadulterated microenvironment can suppress the malignant phenotype and re-direct tumor cells to give rise to normally functioning tissues and indeed healthy mice. One may wonder why such a stunning finding did not convince the scientific community to pay more attention to the role of context. The answers are complex, not the least of which is that concomitantly with this finding, the roles of oncogenes and mutations were being discovered. That excitement carried the day, specially because no one subsequently determined whether or not these mice generated from malignant cells contained tumorigenic mutations, and no new group reproduced the work. The following decade saw the discovery that even potent oncogenes could be ruled by context, and another couple of decades later it was shown that similar reprogramming of metastatic melanoma by an embryonic microenvironment was possible. There are many more examples which are not as clear cut, but are nevertheless compelling. The extensive literature of two-stage carcinogenesis, namely initiation and progression, indeed clearly indicates that 'initiation' and DNA damage alone are not sufficient to allow carcinogenesis. Implicit in these findings is: once a tumor or an oncogene, not always a tumor or an oncogene. A renewed focus on the tumor microenvironment as a therapeutic target has also led to the recognition that markers within the microenvironment could have predictive power. Two recently published reports identifying 'stromal signatures' in breast cancer patients prognostic for patient survival and predictive of ...
Date: June 3, 2009
Creator: Ghajar, Cyrus M.; Meier, Roland & Bissell, Mina J.
Partner: UNT Libraries Government Documents Department

Low Dose Studies with Focused X-Rays in cell and Tissue Models: Mechanisms of Bystander and Genomic Instability Responses

Description: The management of the risks of exposure of people to ionizing radiation is important in relation to its uses in industry and medicine, also to natural and man-made radiation in the environment. The vase majority of exposures are at a very low level of radiation dose. The risks are of inducing cancer in the exposed individuals and a smaller risk of inducing genetic damage that can be indicate that they are low. As a result, the risks are impossible to detect in population studies with any accuracy above the normal levels of cancer and genetic defects unless the dose levels are high. In practice, this means that our knowledge depends very largely on the information gained from the follow-up of the survivors of the atomic bombs dropped on Japanese cities. The risks calculated from these high-dose short-duration exposures then have to be projected down to the low-dose long-term exposures that apply generally. Recent research using cells in culture has revealed that the relationship between high- and low-dose biological damage may be much more complex than had previously been thought. The aims of this and other projects in the DOE's Low-Dose Program are to gain an understanding of the biological actions of low-dose radiation, ultimately to provide information that will lead to more accurate quantification of low-dose risk. Our project is based on the concept that the processes by which radiation induces cancer start where the individual tracks of radiation impact on cells and tissues. At the dose levels of most low-dose exposures, these events are rare and any individual cells only ''sees'' radiation tracks at intervals averaging from weeks to years apart. This contrasts with the atomic bomb exposures where, on average, each cell was hit by hundreds of tracks instantaneously. We have therefore developed microbeam techniques that enable us ...
Date: December 14, 2002
Creator: Held, Kathy; Prise, Kevin; Michael, Barry & Folkard, Melvyn
Partner: UNT Libraries Government Documents Department

Low Dose Studies with Focused X-rays in Cell and Tissue Models: Mechanisms of Bystander and Genomic Instability Responses

Description: The management of the risks of exposure of people to ionizing radiation is important in relation to its uses in industry and medicine, also to natural and man-made radiation in the environment. The vase majority of exposures are at a very low level of radiation dose. The risks are of inducing cancer in the exposed individuals and a smaller risk of inducing genetic damage that can be transmitted to children conceived after exposure. Studies of these risks in exposed population studies with any accuracy above the normal levels of cancer and genetic defects unless the dose levels are high. In practice, this means that our knowledge depends very largely on the information gained from the follow-up of the survivors of the atomic bombs dropped on Japanese cities. The risks calculated from these high-dose short-duration exposures then have to be projected down to the low-dose long-term exposures that apply generally. Recent research using cells in culture has revealed that the relations hi between high- and low-dose biological damage may be much more complex than had previously been thought. The aims of this and other projects in the DOE's Low-Dose Program are to gain an understanding of the biological actions of low-dose radiation, ultimately to provide information that will lead to more accurate quantification of low-dose risk. Our project is based on the concept that the processes by which radiation induces cancer start where the individual tracks of radiation impact on cells and tissues. At the dose levels of most low-dose exposures, these events are rare and any individual cells only ''sees'' radiation tracks at intervals averaging from weeks to years apart. This contracts with the atomic bomb exposures where, on average, each cell was hit by hundreds of tracks instantaneously. We have therefore developed microbeam techniques that enable us to target ...
Date: December 19, 2002
Creator: Michael, Barry D.; Held, Kathryn & Prise, Kevin
Partner: UNT Libraries Government Documents Department

"Research to Improve the Efficacy of Captive Broodstock Programs and Advance Hatchery Reform Throughout the Columbia River Basin." [from the Abstract], 2008-2009 Progress Report.

Description: This project was developed to conduct research to improve the efficacy of captive broodstock programs and advance hatchery reform throughout the Columbia River Basin. The project has three objectives: (1) maintain adaptive life history characteristics in Chinook salmon, (2) improve imprinting in juvenile sockeye salmon, and (3) match wild phenotypes in Chinook and sockeye salmon reared in hatcheries. A summary of the results are as follows: Objective 1: The ratio of jack to adult male Chinook salmon were varied in experimental breeding populations to test the hypothesis that reproductive success of the two male phenotypes would vary with their relative frequency in the population. Adult Chinook salmon males nearly always obtained primary access to nesting females and were first to enter the nest at the time of spawning. Jack male spawning occurred primarily by establishing satellite positions downstream of the courting pair, and 'sneaking' into the nest at the time of spawning. Male dominance hierarchies were fairly stable and strongly correlated with the order of nest entry at the time of spawning. Observed participation in spawning events and adult-to-fry reproductive success of jack and adult males was consistent with a negative frequency-dependent selection model. Overall, jack males sired an average of 21% of the offspring produced across a range of jack male frequencies. Implications of these and additional findings on Chinook salmon hatchery broodstock management will be presented in the FY 2009 Annual Report. Objective 2: To determine the critical period(s) for imprinting for sockeye salmon, juvenile salmon were exposed to known odorants at key developmental stages. Molecular assessments of imprinting-induced changes in odorant receptor gene expression indicated that regulation of odorant expression is influenced by developmental status and odor exposure history. Expression levels of basic amino acid receptor (BAAR) mRNA in the olfactory epithelium increased dramatically during final maturation ...
Date: August 18, 2009
Creator: Berejikian, Barry A.
Partner: UNT Libraries Government Documents Department

Cellular growth and survival are mediated by beta 1 integrins in normal human breast epithelium but not in breast carcinoma

Description: We previously established a rapid three-dimensional assay for discrimination of normal and malignant human breast epithelial cells using a laminin-rich reconstituted basement membrane. In this assay, normal epithelial cells differentiate into well-organized acinar structures whereas tumor cells fail to recapitulate this process and produce large, disordered colonies. The data suggest that breast acinar morphogenesis and differentiation is regulated by cell-extracellular matrix (ECM) interactions and that these interactions are altered in malignancy. Here, we investigated the role of ECM receptors (integrins) in these processes and report on the expression and function of potential laminin receptors in normal and tumorigenic breast epithelial cells. Immmunocytochemical analysis showed that normal and carcinoma cells in a three-dimensional substratum express profiles of integrins similar to normal and malignant breast tissues in situ. Normal cells express {alpha}1, {alpha}2, {alpha}3, {alpha}6, {beta}1 and {beta}4 integrin subunits, whereas breast carcinoma cells show variable losses, disordered expression, or down regulation of these subunits. Function-blocking experiments using inhibitory antiintegrin subunit antibodies showed a >5-fold inhibition of the formation of acinar structures by normal cells in the presence of either anti-{beta}1 or anti-{alpha}3 antibodies, whereas anti-{alpha}2 or -{alpha}6 had little or no effect. In experiments where collagen type I gels were used instead of basement membrane, acinar morphogenesis was blocked by anti-{beta}1 and -{alpha}2 antibodies but not by anti-{alpha}3. These data suggest a specificity of integrin utilization dependent on the ECM ligands encountered by the cell. The interruption of normal acinar morphogenesis by anti-integrin antibodies was associated with an inhibition of cell growth and induction of apoptosis. Function-blocking antibodies had no inhibitory effect on the rate of tumor cell growth, survival or capacity to form colonies. Thus under our culture conditions breast acinar formation is at least a two-step process involving {beta}1-integrin-dependent cellular growth followed by polarization of the cells into organized ...
Date: November 28, 1994
Creator: Howlett, Anthony R; Bailey, Nina; Damsky, Caroline; Petersen, Ole W & Bissell, Mina J
Partner: UNT Libraries Government Documents Department

Expression of Autoactivated Stromelysin-1 in Mammary Glands of Transgenic Mice Leads to a Reactive Stroma During Early Development

Description: Extracellular matrix and extracellular matrix-degrading matrix metalloproteinases play a key role in interactions between the epithelium and the mesenchyme during mammary gland development and disease. In patients with breast cancer, the mammary mesenchyme undergoes a stromal reaction, the etiology of which is unknown. We previously showed that targeting of an autoactivating mutant of the matrix metalloproteinase stromelysin-1 to mammary epithelia of transgenic mice resulted in reduced mammary function during pregnancy and development of preneoplastic and neoplastic lesions. Here we examine the cascade of alterations before breast tumor formation in the mammary gland stroma once the expression of the stromelysin-1 transgene commences. Beginning in postpubertal virgin animals, low levels of transgene expression in mammary epithelia led to increased expression of endogenous stromelysin-1 in stromal fibroblasts and up-regulation of other matrix metalloproteinases, without basement membrane disruption. These changes were accompanied by the progressive development of a compensatory reactive stroma, characterized by increased collagen content and vascularization in glands from virgin mice. This remodeling of the gland affected epithelial-mesenchymal communication as indicated by inappropriate expression of tenascin-C starting by day 6 of pregnancy. This, together with increased transgene expression, led to basement membrane disruption starting by day 15 of pregnancy. We propose that the highly reactive stroma provides a prelude to breast epithelial tumors observed in these animals. Epithelial development depends on an exquisite series of inductive and instructive interactions between the differentiating epithelium and the mesenchymal (stromal) compartment. The epithelium, which consists of luminal and myoepithelial cells, is separated from the stroma by a basement membrane (BM), which plays a central role in mammary gland homeostasis and gene expression. In vivo, stromal cells produce fibronectin, collagens, proteoglycans, and some components of the BM, as well as a number of proteinases that can effectively degrade BM constituents. Stromal and epithelial cells of the ...
Date: April 24, 1998
Creator: Thomasset, N.; Lochter, A.; Sympson, C.J.; Lund, L.R.; Williams, D.R.; Behrendtsen, O. et al.
Partner: UNT Libraries Government Documents Department

In situ quantification of genomic instability in breast cancer progression

Description: Genomic instability is a hallmark of breast and other solid cancers. Presumably caused by critical telomere reduction, GI is responsible for providing the genetic diversity required in the multi-step progression of the disease. We have used multicolor fluorescence in situ hybridization and 3D image analysis to quantify genomic instability cell-by-cell in thick, intact tissue sections of normal breast epithelium, preneoplastic lesions (usual ductal hyperplasia), ductal carcinona is situ or invasive carcinoma of the breast. Our in situ-cell by cell-analysis of genomic instability shows an important increase of genomic instability in the transition from hyperplasia to in situ carcinoma, followed by a reduction of instability in invasive carcinoma. This pattern suggests that the transition from hyperplasia to in situ carcinoma corresponds to telomere crisis and invasive carcinoma is a consequence of telomerase reactivation afertelomere crisis.
Date: May 15, 2003
Creator: Ortiz de Solorzano, Carlos; Chin, Koei; Gray, Joe W. & Lockett, Stephen J.
Partner: UNT Libraries Government Documents Department