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CYTOCIDAL EFFECT OF RIFAMYCIN DERIVATIVES ON ASCITES TUMOR CELLS: STUDIES WITH 125I-IODODEOXYURIDINE

Description: We have previously reported the chemotherapeutic effect of rifamycin derivatives on an ascites tumor, using increased life span as a criterion. These derivatives inhibit (1) RNA-instructed DNA polymerase in crude viral extracts; (2) virus-induced transformation in tissue cultures; and (3) the growth of tumors in vivo. One rifamycin derivative, rifazone-8{sub 2} (R-8{sub 2}), not only inhibits transformation in chick fibroblasts but affects the growth of transformed cells. The present study demonstrates that rifampicin and R-8{sub 2} act as cytocidal (rather than cytostatic) agents against some ascites cell lines.
Date: August 1, 1978
Creator: Hughes, Ann M. & Calvin, Melvin
Partner: UNT Libraries Government Documents Department

Regulation of In Situ to Invasive Breast CarcinomaTransition

Description: The transition of ductal carcinoma in situ (DCIS) to invasive carcinoma is a key event in breast tumor progression that is poorly understood. Comparative molecular analysis of tumor epithelial cells from in situ and invasive tumors has failed to identify consistent tumor stage-specific differences. However, the myoepithelial cell layer, present only in DCIS, is a key distinguishing and diagnostic feature. To determine the contribution of non-epithelial cells to tumor progression, we analyzed the role of myoepithelial cells and fibroblasts in the progression of in situ carcinomas using a xenograft model of human DCIS. Progression to invasion was promoted by fibroblasts, but inhibited by normal myoepithelial cells. The invasive tumor cells from these progressed lesions formed DCIS rather than invasive cancers when re-injected into naive mice. Molecular profiles of myoepithelial and epithelial cells isolated from primary normal and cancerous human breast tissue samples corroborated findings obtained in the xenograft model. These results provide the proof of principle that breast tumor progression could occur in the absence of additional genetic alterations and that tumor growth and progression could be controlled by replacement of normal myoepithelial inhibitory signals.
Date: March 13, 2007
Creator: Hu, Min; Carroll, Danielle K.; Weremowicz, Stanislawa; Chen,Haiyan; Carrasco, Daniel; Richardson, Andrea et al.
Partner: UNT Libraries Government Documents Department

Regulation of in situ to invasive breast carcinoma transition

Description: The transition of ductal carcinoma in situ (DCIS) to invasive carcinoma is a key event in breast tumor progression that is poorly understood. Comparative molecular analysis of tumor epithelial cells from in situ and invasive tumors has failed to identify consistent tumor stage-specific differences. However, the myoepithelial cell layer, present only in DCIS, is a key distinguishing and diagnostic feature. To determine the contribution of non-epithelial cells to tumor progression, we analyzed the role of myoepithelial cells and fibroblasts in the progression of in situ carcinomas using a xenograft model of human DCIS. Progression to invasion was promoted by fibroblasts, but inhibited by normal myoepithelial cells. The invasive tumor cells from these progressed lesions formed DCIS rather than invasive cancers when re-injected into naive mice. Molecular profiles of myoepithelial and epithelial cells isolated from primary normal and cancerous human breast tissue samples corroborated findings obtained in the xenograft model. These results provide the proof of principle that breast tumor progression could occur in the absence of additional genetic alterations and that tumor growth and progression could be controlled by replacement of normal myoepithelial inhibitory signals.
Date: May 7, 2008
Creator: Polyak, Kornelia; Hu, Min; Yao, Jun; Carroll, Danielle K.; Weremowicz, Stanislawa; Chen, Haiyan et al.
Partner: UNT Libraries Government Documents Department

Epimorphin Functions as a Key Morphoregulator for Mammary Epithelial Cells

Description: Hepatocyte growth factor (HGF) and EGF have been reported to promote branching morphogenesis of mammary epithelial cells. We now show that it is epimorphin that is primarily responsible for this phenomenon. In vivo, epimorphin was detected in the stromal compartment but not in lumenal epithelial cells of the mammary gland; in culture, however, a subpopulation of mammary epithelial cells produced significant amounts of epimorphin. When epimorphin-expressing epithelial cell clones were cultured in collagen gels they displayed branching morphogenesis in the presence of HGF, EGF, keratinocyte growth factor, or fibroblast growth factor, a process that was inhibited by anti-epimorphin but not anti-HGF antibodies. The branch length, however, was roughly proportional to the ability of the factors to induce growth. Accordingly, epimorphin-negative epithelial cells simply grew in a cluster in response to the growth factors and failed to branch. When recombinant epimorphin was added to these collagen gels, epimorphin-negative cells underwent branching morphogenesis. The mode of action of epimorphin on morphogenesis of the gland, however, was dependent on how it was presented to the mammary cells. If epimorphin was overexpressed in epimorphin-negative epithelial cells under regulation of an inducible promoter or was allowed to coat the surface of each epithelial cell in a nonpolar fashion, the cells formed globular, alveoli-like structures with a large central lumen instead of branching ducts. This process was enhanced also by addition of HGF, EGF, or other growth factors and was inhibited by epimorphin antibodies. These results suggest that epimorphin is the primary morphogen in the mammary gland but that growth factors are necessary to achieve the appropriate cell numbers for the resulting morphogenesis to be visualized.
Date: October 13, 1997
Creator: Hirai, H.; Lochter, A.; Galosy, S.; Koshida, S.; Niwa, S. & Bissell, M.J.
Partner: UNT Libraries Government Documents Department

Peroxotitanates for Biodelivery of Metals

Description: Metal-based drugs are largely undeveloped in pharmacology. One limiting factor is the systemic toxicity of metal-based compounds. A solid-phase, sequestratable delivery agent for local delivery of metals could reduce systemic toxicity, facilitating new drug development in this nascent area. Amorphous peroxotitanates (APT) are ion exchange materials with high affinity for several heavy metal ions, and have been proposed to deliver or sequester metal ions in biological contexts. In the current study, we tested a hypothesis that APT are able to deliver metals or metal compounds to cells. We exposed fibroblasts (L929) or monocytes (THP1) to metal-APT materials for 72 h in vitro, then measured cellular mitochondrial activity (SDH-MTT method) to assess the biological impact of the metal-APT materials vs. metals or APT alone. APT alone did not significantly affect cellular mitochondrial activity, but all metal-APT materials suppressed the mitochondrial activity of fibroblasts (by 30-65% of controls). The concentration of metal-APT materials required to suppress cellular mitochondrial activity was below that required for metals alone, suggesting that simple extracellular release of the metals from the metal-APT materials was not the primary mechanism of mitochondrial suppression. In contrast to fibroblasts, no metal-APT material had a measurable effect on THP1 monocyte mitochondrial activity, despite potent suppression by metals alone. This latter result suggested that 'biodelivery' by metal-APT materials may be cell type-specific. Therefore, it appears that APT are plausible solid phase delivery agents of metals or metal compounds to some types of cells for potential therapeutic effect.
Date: February 11, 2009
Creator: Hobbs, David & Elvington, M.
Partner: UNT Libraries Government Documents Department

GROWTH REGULATION IN ROUS SARCOMA VIRUS INFECTED CHICKEN EMBRYO FIBROBLASTS: THE ROLE OF THE src GENE

Description: We report here a study of the mechanisms leading to loss of growth control in chicken embryo fibroblasts transformed by Rous sarcoma virus (RSV). We have been particularly concerned with the role of the src gene in this process, and have used RSV mutants temperature sensitive (ts) for transformation to investigate the nature of the growth regulatory lesion. The two principal findings were (1) the stationary phase of the cell cycle (G{sub 1}) in chick embryo fibroblasts seems to have two distinct regulatory compartments (using the terminology of Brooks et al. we refer to these as 'Q' and 'A' states). When rendered stationary at 41.5 C by serum deprivation, normal cells enter a Q state, but cells infected with the ts-mutant occupy an A state. (2) Whereas normal cells can occupy either state depending on culture conditions, the ts-infected cells, at 41.5 C, do not seem to enter Q even though a known src gene product, a kinase, is reported to be inactive at this temperature. We discuss the possibility that viral factors other than the active src protein kinase influence growth control in infected cultures.
Date: July 1, 1980
Creator: Parry, G.; Bartholomew, J.A. & Blssell, M.J.
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

Role for DNA methylation in the regulation of miR-200c and miR-141 expression in normal and cancer cells

Description: BACKGROUND: The microRNA-200 family participates in the maintenance of an epithelial phenotype and loss of its expression can result in epithelial to mesenchymal transition (EMT). Furthermore, the loss of expression of miR-200 family members is linked to an aggressive cancer phenotype. Regulation of the miR-200 family expression in normal and cancer cells is not fully understood. METHODOLOGY/ PRINCIPAL FINDINGS: Epigenetic mechanisms participate in the control of miR-200c and miR-141 expression in both normal and cancer cells. A CpG island near the predicted mir-200c/mir-141 transcription start site shows a striking correlation between miR-200c and miR-141 expression and DNA methylation in both normal and cancer cells, as determined by MassARRAY technology. The CpG island is unmethylated in human miR-200/miR-141 expressing epithelial cells and in miR-200c/miR-141 positive tumor cells. The CpG island is heavily methylated in human miR-200c/miR-141 negative fibroblasts and miR-200c/miR-141 negative tumor cells. Mouse cells show a similar inverse correlation between DNA methylation and miR-200c expression. Enrichment of permissive histone modifications, H3 acetylation and H3K4 trimethylation, is seen in normal miR-200c/miR-141-positive epithelial cells, as determined by chromatin immunoprecipitation coupled to real-time PCR. In contrast, repressive H3K9 dimethylation marks are present in normal miR-200c/miR-141-negative fibroblasts and miR-200c/miR-141 negative cancer cells and the permissive histone modifications are absent. The epigenetic modifier drug, 5-aza-2'-deoxycytidine, reactivates miR-200c/miR-141 expression showing that epigenetic mechanisms play a functional role in their transcriptional control. CONCLUSIONS/ SIGNIFICANCE: We report that DNA methylation plays a role in the normal cell type-specific expression of miR-200c and miR-141 and this role appears evolutionarily conserved, since similar results were obtained in mouse. Aberrant DNA methylation of the miR-200c/141 CpG island is closely linked to their inappropriate silencing in cancer cells. Since the miR-200c cluster plays a significant role in EMT, our results suggest an important role for DNA methylation in the control of phenotypic ...
Date: December 23, 2009
Creator: Vrba, Lukas; Jensen, Taylor J.; Garbe, James C.; Heimark, Ronald L.; Cress, Anne E.; Dickinson, Sally et al.
Partner: UNT Libraries Government Documents Department

Preparation of Single Cells for Imaging Mass Spectrometry

Description: Characterizing chemical changes within single cells is important for determining fundamental mechanisms of biological processes that will lead to new biological insights and improved disease understanding. Imaging biological systems with mass spectrometry (MS) has gained popularity in recent years as a method for creating precise chemical maps of biological samples. In order to obtain high-quality mass spectral images that provide relevant molecular information about individual cells, samples must be prepared so that salts and other cell-culture components are removed from the cell surface and the cell contents are rendered accessible to the desorption beam. We have designed a cellular preparation protocol for imaging MS that preserves the cellular contents for investigation and removes the majority of the interfering species from the extracellular matrix. Using this method, we obtain excellent imaging results and reproducibility in three diverse cell types: MCF7 human breast cancer cells, Madin-Darby canine kidney (MDCK) cells, and NIH/3T3 mouse fibroblasts. This preparation technique allows routine imaging MS analysis of cultured cells, allowing for any number of experiments aimed at furthering scientific understanding of molecular processes within individual cells.
Date: October 24, 2007
Creator: Berman, E S; Fortson, S L; Kulp, K S; Checchi, K D; Wu, L; Felton, J S et al.
Partner: UNT Libraries Government Documents Department

Adaptive Response Against Spontaneous Neoplastic Transformation In Vitro Induced by Ionizing Radiation

Description: The goal of this project was to establish a dose response curve for radiation-induced neoplastic transformation of HeLa x skin fibroblast human hybrid cells in vitro under experimental conditions were an adaptive response, if it were induced, would have an opportunity to be expressed. During the first two years of the grant an exhaustive series of experiments were performed and the resulting data were reported at the 2000 Annual Meeting of the Radiation Research Society and then Subsequently published. The data showed that an adaptive response against spontaneous neoplastic transformation was seen up to doses of 10cGy of Cs-137 gamma rays. At dose of 30, 50 and 100 cGy the transformation frequencies were above background. This indicated that for this system, under the specific experimental conditions used, there was a threshold of somewhere between 10 and 30 cGy. The results also indicated some unexpected, though very interesting, correlations with relative risk estimates made from human epidemiologic studies.
Date: November 10, 2003
Creator: J. Leslie Redpath, Ph.D.
Partner: UNT Libraries Government Documents Department

Stromal-epithelial interactions in aging and cancer: Senescent fibroblasts alter epithelial cell differentiation

Description: Cellular senescence suppresses cancer by arresting cells at risk for malignant tumorigenesis. However, senescent cells also secrete molecules that can stimulate premalignant cells to proliferate and form tumors, suggesting the senescence response is antagonistically pleiotropic. We show that premalignant mammary epithelial cells exposed to senescent human fibroblasts in mice irreversibly lose differentiated properties, become invasive and undergo full malignant transformation. Moreover, using cultured mouse or human fibroblasts and non-malignant breast epithelial cells, we show that senescent fibroblasts disrupt epithelial alveolar morphogenesis, functional differentiation, and branching morphogenesis. Further, we identify MMP-3 as the major factor responsible for the effects of senescent fibroblasts on branching morphogenesis. Our findings support the idea that senescent cells contribute to age-related pathology, including cancer, and describe a new property of senescent fibroblasts--the ability to alter epithelial differentiation--that might also explain the loss of tissue function and organization that is a hallmark of aging.
Date: July 14, 2004
Creator: Parrinello, Simona; Coppe, Jean-Philippe; Krtolica, Ana & Campisi, Judith
Partner: UNT Libraries Government Documents Department

Dose-dependent misrejoining of radiation-induced DNA double-strand breaks in human fibroblasts: Experimental and theoretical study for high and low LET radiation

Description: Misrejoining of DNA double-strand breaks (DSBs) was measured in human primary fibroblasts after exposure to X-rays and high LET particles (He, N and Fe) in the dose range 10-80 Gy. To measure joining of wrong DNA ends, the integrity of a 3.2 Mbp restriction fragment was analyzed directly after exposure and after 16 hr of repair incubation. It was found that the misrejoining frequency for X-rays was non-linearly related to dose, with less probability of misrejoining at low doses than at high doses. The dose dependence for the high LET particles, on the other hand, was closer to being linear, with misrejoining frequencies higher than for X-rays particularly at the lower doses. These experimental results were simulated with a Monte-Carlo approach that includes a cell nucleus model with all 46 chromosomes present, combined with realistic track structure simulations to calculate the geometrical positions of all DSBs induced for each dose. The model assumes that the main determinant for misrejoining probability is the distance between two simultaneously present DSBs. With a Gaussian interaction probability function with distance, it was found that both the low and high LET data could be fitted with an interaction distance (sigma of the Gaussian curve) of 0.25 {micro}m. This is half the distance previously found to best fit chromosomal aberration data in human lymphocytes using the same methods (Holley et al. Radiat. Res . 158, 568-580 (2002)). The discrepancy may indicate inadequacies in the chromosome model, for example insufficient chromosomal overlap, but may also partly be due to differences between fibroblasts and lymphocytes. Although the experimental data was obtained at high doses, the Monte Carlo calculations could be extended to lower doses. It was found that a linear component of misrejoining versus dose dominated for doses below 1 Gy for all radiations, including X-rays. The calculated ...
Date: November 18, 2004
Creator: Rydberg, Bjorn; Cooper, Brian; Cooper, Priscilla K.; Holley, William & Chatterjee, Aloke
Partner: UNT Libraries Government Documents Department

Disruption of NBS1 gene leads to early embryonic lethality in homozygous null mice and induces specific cancer in heterozygous mice

Description: Nijmegen breakage syndrome (NBS) is a rare autosomal recessive chromosome instability syndrome characterized by microcephaly, growth retardation, immunodeficiency, and cancer predisposition, with cellular features similar to that of ataxia telangiectasia (AT). NBS results from mutations in the mammalian gene Nbs1 that codes for a 95-kDa protein called nibrin, NBS1, or p95. To establish an animal model for NBS, we attempted to generate NBS1 knockout mice. However, NBS1 gene knockouts were lethal at an early embryonic stage. NBS1 homozygous(-/-) blastocyst cells cultured in vitro showed retarded growth and subsequently underwent growth arrest within 5 days of culture. Apoptosis, assayed by TUNEL staining, was observed in NBSI homozygous(-/-) blastocyst cells cultured for four days. NBSI heterozygous(+/-) mice were normal, and exhibited no specific phenotype for at least one year. However, fibroblast cells from NBSI heterozygous(+/-) mice displayed an enhanced frequency of spontaneous transformation to anchorage-independent growth as compared to NBS1 wild-type(+/+) cells. Furthermore, heterozygous(+/-) mice exhibited a high incidence of hepatocellular carcinoma after one year compared to wild-type mice, even though no significant differences in the incidence of other tumors such as lung adenocarcinoma and lymphoma were observed. Taken together, these results strongly suggest that NBS1 heterozygosity and reduced NBSI expression induces formation of specific tumors in mice.
Date: April 15, 2002
Creator: Kurimasa, Akihiro; Burma, Sandeep; Henrie, Melinda; Ouyang, Honghai; Osaki, Mitsuhiko; Ito, Hisao et al.
Partner: UNT Libraries Government Documents Department

GROWTH REGULATION IN RSV INFECTED CHECKEN EMBRYO FIBROBLASTS: THE ROLE OF THE src GENE

Description: The relationship between growth regulation and cell transformation has been studied in many cultured cell lines transformed by a range of oncogenic agents. The main conclusion derived from these investigations is that the nature of the growth regulatory lesion in transformed cells is a function of the agent used to induce transformation. For example, when 3T3 fibroblasts are rendered stationary by serum deprivation, normal cells accumulate in G{sub 1} but SV40 transformed cells are arrested at all stages of the cell cycle. In contrast, 3T3 cells transformed with Rous sarcoma virus B77, accumulate in G{sub 1} upon serum deprivation. This is also true when mouse sarcoma virus (MSV) is used as the transforming agent. MSV-transformed cells accumulate in G{sub 1}, just as do normal cells. In this letter we report a detailed study of the mechanisms leading to loss of growth control in chicken embryo fibroblasts transformed by Rous sarcoma virus (RSV). We have been particularly concerned with the role of the src gene in the process, and have used RSV mutants temperature sensitive (ts) for transformation to investigate the nature of the growth regulatory lesion. Two principal findings have emerged: (a) the stationary phase of the cell cycle (G{sub 1}) in chick embryo fibroblasts has two distinct compartments, (for simplicity referred to as G{sub 1} and G{sub 0} states), (b) when rendered stationary at 41.5{sup o} by serum deprivation, normal cells enter a G{sub 0}-like state, but cells infected with the ts-mutant occupy a G{sub 1} state, even though a known src gene product, a kinase, should be inactive at this temperature. The possibility is discussed that viral factors other than the active src protein kinase influence growth control.
Date: March 1, 1980
Creator: Parry, G.; Bartholomew, J.C. & Bissell, M.J.
Partner: UNT Libraries Government Documents Department

Senescence-Associated Secretory Phenotypes Reveal Cell-Nonautonomous Functions of Oncogenic RAS and the p53 Tumor Suppressor

Description: Cellular senescence suppresses cancer by arresting cell proliferation, essentially permanently, in response to oncogenic stimuli, including genotoxic stress. We modified the use of antibody arrays to provide a quantitative assessment of factors secreted by senescent cells. We show that human cells induced to senesce by genotoxic stress secrete myriad factors associated with inflammation and malignancy. This senescence-associated secretory phenotype (SASP) developed slowly over several days and only after DNA damage of sufficient magnitude to induce senescence. Remarkably similar SASPs developed in normal fibroblasts, normal epithelial cells, and epithelial tumor cells after genotoxic stress in culture, and in epithelial tumor cells in vivo after treatment of prostate cancer patients with DNA-damaging chemotherapy. In cultured premalignant epithelial cells, SASPs induced an epithelial-mesenchyme transition and invasiveness, hallmarks of malignancy, by a paracrine mechanism that depended largely on the SASP factors interleukin (IL)-6 and IL-8. Strikingly, two manipulations markedly amplified, and accelerated development of, the SASPs: oncogenic RAS expression, which causes genotoxic stress and senescence in normal cells, and functional loss of the p53 tumor suppressor protein. Both loss of p53 and gain of oncogenic RAS also exacerbated the promalignant paracrine activities of the SASPs. Our findings define a central feature of genotoxic stress-induced senescence. Moreover, they suggest a cell-nonautonomous mechanism by which p53 can restrain, and oncogenic RAS can promote, the development of age-related cancer by altering the tissue microenvironment.
Date: October 24, 2008
Creator: Coppé, Jean-Philippe; Patil, Christopher; Rodier, Francis; Sun, Yu; Munoz, Denise; Goldstein, Joshua et al.
Partner: UNT Libraries Government Documents Department

Ascorbic acid inhibits replication and infectivity of avian RNA tumor virus

Description: Ascorbic acid, at nontoxic concentrations, causes a substantial reduction in the ability of avian tumor viruses to replicate in both primary avian tendon cells and chicken embryo fibroblasts. The virus-infected cultures appear to be less transformed in the presence of ascorbic acid by the criteria of morphology, reduced glucose uptake, and increased collagen synthesis. The vitamin does not act by altering the susceptibility of the cells to initial infection and transformation, but instead appears to interfere with the spread of infection through a reduction in virus replication and virus infectivity. The effect is reversible and requires the continuous presence of the vitamin in the culture medium.
Date: April 1, 1980
Creator: BISSELL, MINA J; HATIE, CARROLL; FARSON, DEBORAH A.; SCHWARZ, RICHARD I. & SOO, WHAI-JEN
Partner: UNT Libraries Government Documents Department

Low dose radiation hypersensitivity and clustered DNA damages in human fibroblasts exposed to low dose and dose rate protons or 137CS y-rays

Description: Effective radioprotection for human space travelers hinges upon understanding the individual properties of charged particles. A significant fraction of particle radiation astronauts will encounter in space exploratory missions will come from high energy protons in galactic cosmic radiation (GCR) and/or possible exposures to lower energy proton flux from solar particle events (SPEs). These potential exposures present major concerns for NASA and others, in planning and executing long term space exploratory missions. We recently reported cell survival and transformation (acquisition of anchorage-independent growth in soft agar) frequencies in apparently normal NFF-28 primary human fibroblasts exposed to 0-30 cGy of 50MeV, 100MeV (SPE-like), or 1000 MeV (GCR-like) monoenergetic protons. These were modeled after 1989 SPE energies at an SPE-like low dose-rate (LDR) of 1.65 cGy/min or high dose rate (HDR) of 33.3 cGy/min delivered at the NASA Space Radiation Laboratory (NSRL) at BNL.
Date: May 14, 2013
Creator: Bennett, P. V.; Keszenman, D. J.; Johnson, A. M.; Sutherland, B. M. & Wilson, P. F.
Partner: UNT Libraries Government Documents Department

Putting Tumors in Context

Description: The interactions between cancer cells and their micro- and macroenvironment create a context that promotes tumor growth and protects it from immune attack. The functional association of cancer cells with their surrounding tissues forms a new 'organ' that changes as malignancy progresses. Investigation of this process might provide new insights into the mechanisms of tumorigenesis and could also lead to new therapeutic targets. Under normal conditions, ORGANS are made up of TISSUES that exchange information with other cell types via cell-cell contact, cytokines and the EXTRACELLULAR MATRIX (ECM). The ECM, which is produced by collaboration between STROMAL fibroblasts and EPITHELIAL cells, provides structural scaffolding for cells, as well as contextual information. The endothelial vasculature provides nutrients and oxygen, and cells of the immune system combat pathogens and remove apoptotic cells. Epithelial cells associate into intact, polarized sheets. These tissues communicate through a complex network of interactions: physically, through direct contact or through the intervening ECM, and biochemically, through both soluble and insoluble signalling molecules. In combination, these interactions provide the information that is necessary to maintain cellular differentiation and to create complex tissue structures. Occasionally, the intercellular signals that define the normal context become disrupted. Alterations in epithelial tissues can lead to movement of epithelial sheets and proliferation - for example, after activation of mesenchymal fibroblasts due to wounding.Normally, these conditions are temporary and reversible, but when inflammation is sustained, an escalating feedback loop ensues.Under persistent inflammatory conditions, continual upregulation of enzymes such as matrix metalloproteinases (MMPs) by stromal fibroblasts can disrupt the ECM, and invading immune cells can overproduce factors that promote abnormal proliferation. As this process progresses, the normal organization of the organ is replaced by a functional disorder. If there are pre-existing epithelial cells within this changing context that possess tumorigenic potential, they can start to proliferate. ...
Date: October 1, 2001
Creator: Bissell, Mina & Radisky, Derek
Partner: UNT Libraries Government Documents Department

CLOSTRIDIUM SPORE ATTACHMENT TO HUMAN CELLS

Description: This paper uses high resolution scanning electron microscopy (SEM) with a LaB6 gun and the newest commercial field emission guns, to obtain high magnification images of intact clostridial spores throughout the activation/germination/outgrowth process. By high resolution SEM, the clostridial exosporial membrane can be seen to produce numerous delicate projections (following activation), that extend from the exosporial surface to a nutritive substrate (agar), or cell surface when anaerobically incubated in the presence of human cells (embryonic fibroblasts and colon carcinoma cells). Magnifications of 20,000 to 200,000Xs at accelerating voltages low enough to minimize or eliminate specimen damage (1--5 kV) have permitted the entire surface of C.sporogenes and C.difficile endospores to be examined during all stages of germination. The relationships between the spore and the agar or human cell surface were also clearly visible.
Date: August 10, 1997
Creator: PANESSA-WARREN,B.; TORTORA,G. & WARREN,J.
Partner: UNT Libraries Government Documents Department

Adaptive Response Against Spontaneous Neoplastic Transformation In Vitro Induced by Ionizing Radiation

Description: response curve for radiation-induced neoplastic transformation of HeLa x skin fibroblast human hybrid cells in vitro under experimental conditions where an adaptive response, if it were induced, would have an opportunity to be expressed. During the first two years of the grant an exhaustive series of experiments were performed and the resulting data were reported at the 2000 Annual Meeting of the Radiation Research Society and then subsequently published (Redpath et al., 2001). The data showed that an adaptive response against spontaneous neoplastic transformation was seen up to doses of 10cGy of Cs-137 gamma rays. At dose of 30, 50 and 100 cGy the transformation frequencies were above background. This indicated that for this system, under the specific experimental conditions used, there was a threshold of somewhere between 10 and 30 cGy. The results also indicated some unexpected, though very interesting, correlations with relative risk estimates made from human epidemiologic studies (for details see the Redpath et al., 2001 ).
Date: June 1, 2002
Creator: Redpath, J. Leslie
Partner: UNT Libraries Government Documents Department

Analysis of Flow Cytometry DNA Damage Response Protein Activation Kinetics Following X-rays and High Energy Iron Nuclei Exposure

Description: We developed a mathematical method to analyze flow cytometry data to describe the kinetics of {gamma}H2AX and pATF2 phosphorylations ensuing various qualities of low dose radiation in normal human fibroblast cells. Previously reported flow cytometry kinetic results for these DSB repair phospho-proteins revealed that distributions of intensity were highly skewed, severely limiting the detection of differences in the very low dose range. Distributional analysis reveals significant differences between control and low dose samples when distributions are compared using the Kolmogorov-Smirnov test. Radiation quality differences are found in the distribution shapes and when a nonlinear model is used to relate dose and time to the decay of the mean ratio of phosphoprotein intensities of irradiated samples to controls. We analyzed cell cycle phase and radiation quality dependent characteristic repair times and residual phospho-protein levels with these methods. Characteristic repair times for {gamma}H2AX were higher following Fe nuclei as compared to X-rays in G1 cells (4.5 {+-} 0.46 h vs 3.26 {+-} 0.76 h, respectively), and in S/G2 cells (5.51 {+-} 2.94 h vs 2.87 {+-} 0.45 h, respectively). The RBE in G1 cells for Fe nuclei relative to X-rays for {gamma}H2AX was 2.05 {+-} 0.61 and 5.02 {+-} 3.47, at 2 h and 24-h postirradiation, respectively. For pATF2, a saturation effect is observed with reduced expression at high doses, especially for Fe nuclei, with much slower characteristic repair times (>7 h) compared to X-rays. RBEs for pATF2 were 0.66 {+-} 0.13 and 1.66 {+-} 0.46 at 2 h and 24 h, respectively. Significant differences in {gamma}H2AX and pATF2 levels comparing irradiated samples to control were noted even at the lowest dose analyzed (0.05 Gy) using these methods of analysis. These results reveal that mathematical models can be applied to flow cytometry data to uncover important and subtle differences following exposure to ...
Date: December 15, 2010
Creator: Association, Universities Space Research; Chappell, Lori J.; Whalen, Mary K.; Gurai, Sheena; Ponomarev, Artem; Cucinotta, Francis A. et al.
Partner: UNT Libraries Government Documents Department

Determine the yield of micronucleated cells in primary human fibroblasts exposed to focused soft X-rays.

Description: This project was a small part of a larger collaborative study headed by Dr Aloke Chatterjee, (Lawrence Berkeley National Laboratory) and including Drs Les Braby, John Ford (Texas A&M) and Kathy Held (MGH Boston), which was developing an integrated theoretical and experimental model of the radiation-induced bystander response. Our part of the study has been to determine the effectiveness of soft X-rays at inducing chromosomal damage under conditions of direct and bystander exposure. The aim was to compare this with the effectiveness of the low energy 60 kV electron microbeam available at Texas A&M. Previous studies have been performed with primary human fibroblasts measuring micronuclei formation to determine the relative yields of direct versus bystander mediated micronuclei formation after cells were individually irradiated utilizing our novel focused soft X-ray microprobe, which is capable of producing localized submicron beams of carbon-K (278 eV) X-rays. Only a brief overview is given here as the study has been published in several papers. Our original hypothesis was to study yields of bystander-induced micronucleated cells in both wild-type and mutant fibroblast from mouse embryo fibroblasts. Difficulties with the level of background micronuclei in the MEFs prevented systematic studies of bystander responses in the laboratories involved in the collaboration. We then performed these studies with AG1522 primary human fibroblast cells using a siRNA approach developed by John Ford at Texas A&M to knock down DNA PKcs in the first instance. Our soft X-ray source has been in routine use for carbon-K X-rays and is now available with Aluminium-K (1.49 keV) and titanium-K (4.5 keV), although the dose-rate from titanium is still too low at present for most experiments, where large numbers of cells need to be exposed. A separately funded project developed a new soft X-ray microprobe which will give much greater flexibility for changing energies ...
Date: January 2, 2007
Creator: Prise, Kevin M.
Partner: UNT Libraries Government Documents Department

CELL SHAPE AND HEXOSE TRANSPORT IN NORMAL AND VIRUS-TRANSFORMED CELLS IN CULTURE

Description: The rate of hexose transport was compared in normal and virus-transformed cells on a monolayer and in suspension. It was shown that: (1) Both trypsin-removed cells and those suspended for an additional day in methyl cellulose had decreased rates of transport and lower available water space when compared with cells on a monolayer. Thus, cell shape affects the overall rate of hexose transport, especially at higher sugar concentrations. (2) Even in suspension, the initial transport rates remained higher in transformed cells with reference to normal cells. Scanning electron micrographs of normal and transformed chick cells revealed morphological differences only in the flat state. This indicates that the increased rate of hexose transport after transformation is not due to a difference in the shape of these cells on a monolayer. The relation between the geometry of cells, transport rates, and growth regulation is undoubtedly very complex, and our knowledge of these relationships is still very elementary. In a recent review on the influence of geometry on control of cell growth, Folkman and Greenspan (1) pointed out that the permeability of cells in a flat versus a spherical state may indeed be very different. The growth properties of cells on a surface and in suspension have been compared often (1-5). However, with one exception. little is known about the changes in transport properties when cell shape is changed. Foster and Pardee (6) demonstrated that the active transport of a-aminoisobutyric acid was reduced 2.5 times in suspension cultures of Chinese hamster cells with respect to the cells grown on a coverslip. They attributed this to the smaller surface area of suspended cells. While it is not clear why active transport should be dependent on the surface area available, it is possible that once the cells assume a spherical configuration, the carrier proteins are ...
Date: July 1, 1976
Creator: Bissell, M.J.; Farson, D. & Tung, A.S.C.
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