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K J Pienta

Publications and source records attributed to K J Pienta.

At least 109 records · Page 6Linked to original sources
PubMed1992

The effect of age on the response of the detrusor to intracellular mechanical stimulus: DNA replication and the cell actin matrix.

Benign prostatic hypertrophy and posterior urethral valves present at both extremes of the age spectrum. Both disease processes can obstruct the urinary stream and ultimately have pathophysiological effects on detrusor structure and function. The mechanisms regulating the structural reorganization of the detrusor to a mechanical outflow obstruction are not known. In an attempt to identify maturational differences in myocyte ultrastructure and consequent effects these might have in modifying the response of the detrusor to mechanical stimulus, we studied differences in dynamic nuclear-cytoskeletal interactions in detrusor tissue in an animal model. Using a drug which specifically severs actin, cytochalasin D (CD), as an intracellular mechanical stimulus, we measured changes in nuclear area and the rate of DNA synthesis in detrusor myocytes from young (2-3 week) and old (8-12 mon) guinea pigs. We found that there were age specific differences to intracellular mechanical stimuli in detrusor muscle. Nuclei of myocytes from young animals showed elastic recoil on severing the cell actin matrix and the tissue from young animals increased replicative DNA synthesis with an intracellular stimulus. In contrast, nuclear shape changes in myocytes from old animals suggested less elasticity, and there was no increase in DNA synthesis with disruption of the cell actin matrix. Anti-alpha-smooth muscle actin antibody and rhodamine phalloidin staining of actin in cytochalasin D treated primary explants of detrusor myocytes showed dose dependent disruption of the actin component of the cytoskeleton. These results suggest that there are fundamental modifications in detrusor myocyte ultrastructure with age. These maturational changes might result in differences in the pathophysiological and structural reorganization of the detrusor in response to outflow obstruction in infancy and adulthood. Furthermore, they suggest that 1) a tensile equilibrium exists between the myocyte nucleus and cytoskeleton; 2) there appears to be a decrease in myocyte nuclear elasticity with ageing; 3) release of nuclear template restrictions increases activity of DNA polymerase alpha in young, but not old, detrusor myocytes; and 4) mechanico-chemical signal transduction in detrusor myocytes may be mediated via the cytoskeleton. In addition, based on previous reports of actin within the nucleus, the results suggest that 1) nuclear actin may have a homeostatic structural role, maintaining the tensile equilibrium between nucleus and cytoskeleton, and 2) integrity of nuclear actin may function to maintain the spatial template restriction on DNA polymerase alpha activity.

Actins↗
PubMed1992

Nuclear-cytoskeletal interactions: evidence for physical connections between the nucleus and cell periphery and their alteration by transformation.

The overall coordination of cell structure and function that results in gene expression requires a spatial and temporal precision that would be unobtainable in the absence of structural order within the cell. Cells contain extensive and elaborate three-dimensional skeletal networks that form integral structural components of the plasma membrane, cytoplasm, and nucleus. These skeletal networks form a dynamic tissue matrix are composed of the nuclear matrix, cytoskeleton, and extracellular matrix. The tissue matrix is an interactive network which undergoes dynamic changes as cells move and change shape. Pathologists have long recognized cancer in pathologic specimens based on the altered morphology of tumor cells compared to their normal counterparts. The structural order of cells appears to be altered in transformed cells. This structural order is reflected in the altered morphology and motility observed in transformed cells compared to their normal counterparts, however, it is unclear whether the structural changes observed in cancer cells have any functional significance. We report here on the nature of the physical connections between the nucleus and cell periphery in nontransformed cells and demonstrate that the nucleus is dynamically coupled to the cell periphery via actin microfilaments. We also demonstrate that the dynamic coupling of the nucleus to the cell periphery via actin microfilaments is altered in Kirsten-ras transformed rat kidney epithelial cells. This loss of structure-function relationship may be an important factor in the process of cell transformation.

Acrylamide↗
PubMed1992

Effects of extracellular matrix components and dihydrotestosterone on the structure and function of human prostate cancer cells.

The extracellular matrix (ECM) has been shown to play a major role in cell structure and function. Several studies have demonstrated that the ECM can alter cell morphology and effect DNA synthesis and gene expression. The ECM also interacts with growth hormones which have been shown to be located in or near the ECM where they are believed to effect cell structure and function. In the nontransformed cell, these ECM and hormone-mediated effects appear to be tightly regulated and this is believed to be accomplished through cell receptor-tissue matrix interactions. We, therefore, undertook a study to determine the effects of a variety of ECM components and the adrogenic hormone dihydrotestosterone (DHT) on the structure and function of the human prostate cancer cell line, LNCaP. The effects of individual matrix components in the presence and absence of 1 nM DHT on the static and dynamic morphology, growth rate, and PSA production of the LNCaP cell line were studied. We determine that the ECM and DHT interact in complex ways to effect cell structure and function. DHT produced alterations in cytoplasmic structure that increased cell size and decreased the nuclear area/cytoplasmic area ratio. Dynamic cell structure as measured by cell motility was very sensitive to the ECM components and the presence of DHT. PSA and growth could be regulated by substratum and DHT and there was an inverse relationship between PSA production and growth rate. These data exemplify the complex interactions which occur between prostate cancer cells, ECM components, and exogenous DHT that are reflected in cell structure and function.

Antigens, Neoplasm↗
PubMed1992

Effect of pentosan, a novel cancer chemotherapeutic agent, on prostate cancer cell growth and motility.

Pentosan is a new chemotherapeutic drug which is currently in Phase I clinical trials. In our experimental systems, in vivo, pentosan inhibits the growth of the highly metastatic MAT-LyLu (MLL) Dunning R3327 prostate cancer cell line only at toxic doses and has no apparent effect on growth in vitro. The mechanism of tumor inhibition of this drug is unknown; however, in vitro, pentosan exhibits a potent inhibition of cell motility. Cell motility is essential for tumor cell metastasis and angiogenesis. By blocking cell motility, pentosan has the potential to inhibit both tumor growth and metastasis. We have characterized the mechanism of motility inhibition by pentosan and believe it alters cell-extracellular matrix interactions. The mechanism of motility inhibition by pentosan appears to be independent of cytoskeletal structural alterations, including changes in microfilament and microtubule networks. Pentosan acts through a different mechanism than suramin, a drug which inhibits motility through inhibition of growth factor effects. In vitro, pentosan alters cellular contacts with the extravascular matrix and inhibits cell motility. In vivo, pentosan prolongs survival of rats injected with MLL cells by 25%, but did not appear to decrease the rate of primary tumor growth or the number of metastatic lesions in the treated animals. These data suggest that, in vivo, pentosan acts through an as yet undefined mechanism.

Animals↗
PubMed1992

Characterization of nuclear morphology and nuclear matrices in ageing human fibroblasts.

It is believed that the mechanisms for cellular senescence may reside within the genome, however, the changes which occur in the DNA and the surrounding nuclear environment have not been well documented. As the dynamic skeletal framework of the nucleus, the nuclear matrix is poised to play a critical role in the ageing process. The nuclear matrix plays a central role in DNA organization and nuclear structural morphology. The important roles of the nuclear matrix in cell structure and function are demonstrated by its properties of tissue specificity and that it is altered by viral infection, differentiation and carcinogenesis. We therefore undertook a study to investigate the morphologic alterations which occur in ageing nuclei and to determine whether compositional changes in the nuclear matrix occur with age in human skin fibroblasts. We found that as the nucleus increases in size and becomes more round with age, the qualitative pattern of the prominent nuclear matrix proteins does not appear to undergo major changes with age. There do, however, appear to be quantitative alterations in these proteins.

Cell Line↗
PubMed1991

Identification of nuclear matrix proteins in the cancer and normal rat prostate.

The nuclear matrix is the structural component of the nucleus that determines nuclear morphology and organizes the DNA in a three-dimensional fashion that is tissue specific. Previously, some of the nuclear matrix proteins have been reported to be both tissue and cell type specific and are altered with the state of differentiation and transformation. This study demonstrates that the nuclear matrix is specific for the individual lobes of the normal rat prostate and that the nuclear matrix undergoes changes in protein composition in the Dunning prostate cancer tissue. Additionally, in the Dunning rat prostate adenocarcinoma cell lines, there is a range of tumor phenotypes and the nuclear matrix varies in composition in each tumor cell type. These differences in the nuclear matrix proteins are associated with quantitative changes in nuclear morphology that form the pleiomorphic state of the cancer nucleus.

Adenocarcinoma↗
PubMed1991

Correlation of nuclear morphometry with progression of breast cancer.

Alterations in nuclear structure are the morphologic hallmark of cancer diagnosis. Nuclear size, shape, chromatin pattern, and nucleolar size and number have all been reported to change in breast cancer. Attempts to quantify nuclear alterations to establish grading systems, predict prognosis, and/or set guidelines for therapy have met with varied success. Therefore, the authors quantified the changes that occur with breast cancer with nuclear morphology in several different groups of patients: normal controls, intraductal carcinoma, invasive ductal carcinoma with negative nodes at mastectomy, and invasive ductal carcinoma with positive lymph nodes. Pleomorphism as measured by both nuclear area and intrasample variation increased with invasive histology and metastatic breast cancer. It is still unclear whether node-negative Stage II breast cancer requires adjuvant therapy. This issue would be less complicated if it were possible to identify those women at high risk of recurrence. Therefore, the authors retrospectively identified 30 women with node-negative Stage II infiltrating ductal carcinoma with a long follow-up period of 6 to 12 years. Computer-assisted morphometry of nuclei in routine hematoxylin and eosin-stained pathologic slides was done using the DynaCell Analysis System in a blinded fashion. DynaCell measures 15 nuclear parameters, including perimeter, area volume, roundness, and ellipticity. Although nuclear area and variance were related to breast cancer progression, nuclear morphometry did not predict successfully which patients would have recurrent disease in the women with Stage II, node-negative lesions at the time of mastectomy.

Adult↗
PubMed1991

The effect of extracellular matrix interactions on morphologic transformation in vitro.

There is emerging evidence that the structure and function of a cell is dependent in part on the contacts that cells make with the extracellular matrix. We report here the effect of extracellular matrices secreted from both normal and tumor cells have on the structure of normal rat kidney epithelial cells. Normal rat kidney cells plated on the basement membrane secreted by tumor cells adopt a morphology and phenotype which closely resembles a Kirsten-ras transformed normal rat kidney cell. This morphologic transformation was not observed for cells plated on individual extracellular matrix components or on basement membrane secreted by normal placenta cells. This suggests that tumor derived basement membrane has unique characteristics which may cause morphologic transformation of normal rat kidney cells.

Animals↗
PubMed1991

Modifications of the intermediate filament and nuclear matrix networks by the extracellular matrix.

The tissue matrix system is a dynamic, interacting structural network directly linking the nuclear matrix, cytoskeleton and the extracellular matrix. We report here that interaction of normal rat kidney epithelial cells (NRK) and Kirsten-ras transformed rat kidney cells, with an extracellular matrix secreted by tumor cells, causes modifications to the protein composition of the intermediate filament and nuclear matrix networks. The matrix networks are different between normal and transformed cells; however, these alterations by the tumor extracellular matrix are similar in both cell types. These data represent the first report that modification of the extracellular matrix environment can have an effect on the protein composition of the nuclear matrix.

Animals↗
PubMed1991

Preneoplastic alterations in nuclear morphology that accompany loss of tumor suppressor phenotype.

Alterations of nuclear shape are frequently observed in tumor cells, but the genes controlling these changes and the stage in the neoplastic process at which they occur are unknown. We have studied nuclear shape changes in chemically immortalized, nontumorigenic Syrian hamster embryo cell clones that had either retained (supB+) or lost (supB-) the ability to suppress the tumorigenic phenotype when they were hybridized with a tumor cell line (BP6T). Quantitative morphometric analysis of the nuclei of cells from each of two pairs of supB+/supB- variants indicated that the nuclei of supB- cells were significantly more out of round than those of their corresponding supB+ clones. These data indicate that modification of nuclear structure may represent an early, preneoplastic event in multistep chemical carcinogenesis and that loss of a tumor suppressor gene function may regulate alterations in nuclear morphology.

Animals↗
PubMed1991

Nuclear structure and the three-dimensional organization of DNA.

The organization of DNA within the nucleus has been demonstrated to be both cell and tissue specific and is arranged in a non-random fashion in both sperm and somatic cells. Nuclear structure has a pivotal role in this three-dimensional organization of DNA and RNA and contributes as well to forming fixed organizing sites for nuclear functions, such as DNA replication, transcription, and RNA processing. In sperm, DNA is also organized in a specific fashion by the nuclear matrix and DNA-protamine interactions. Within somatic cells, the nuclear matrix provides a three-dimensional framework for the tissue specific regulation of genes by directed interaction with transcriptional activators. This differential organization of the DNA by the nuclear matrix, in a tissue specific manner, contributes to tissue specific gene expression. The nuclear matrix is the first link from the DNA to the entire tissue matrix system and provides a direct structural linkage to the cytomatrix and extracellular matrix. In summary, the tissue matrix serves as a dynamic structural framework for the cell which interacts to organize and process spatial and temporal information to coordinate cellular functions and gene expression. The tissue matrix provides a structural system for integrating form and function.

Animals↗
PubMed1991

Cellular harmonic information transfer through a tissue tensegrity-matrix system.

Cells and intracellular elements are capable of vibrating in a dynamic manner with complex harmonics, the frequency of which can now be measured and analyzed in a quantitative manner by Fourier analysis. Cellular events such as changes in shape, membrane ruffling, motility, and signal transduction occur within spatial and temporal harmonics that have potential regulatory importance. These vibrations can be altered by growth factors and the process of carcinogenesis. It is important to understand the mechanism by which this vibrational information is transferred directly throughout the cell. From these observations we propose that vibrational information is transferred through a tissue tensegrity-matrix which acts as a coupled harmonic oscillator operating as a signal transucing system from the cell periphery to the nucleus and ultimately to the DNA. The vibrational interactions occur through a tissue matrix system consisting of the nuclear matrix, the cytoskeleton, and the extracellular matrix that is poised to couple the biologic oscillations of the cell from the peripheral membrane to the DNA through a tensegrity-matrix structure. Tensegrity has been defined as a structural system composed of discontinuous compression elements connected by continuous tension cables, which interact in a dynamic fashion. A tensegrity tissue matrix system allows for specific transfer of information through the cell by direct transmission of vibrational chemomechanical energy through harmonic wave motion.

Animals↗
PubMed1991

The effects of basic fibroblast growth factor and suramin on cell motility and growth of rat prostate cancer cells.

Suramin, a new type of cancer chemotherapeutic agent with growth factor antagonist properties, has been reported to affect growth of prostate cancer metastatic lesions. Partin et al. have previously reported that prostate cancer cell motility was essential for tumor cell metastasis. We have studied the effects of suramin on cell motility and cell growth in a prostate cancer cell model. We have demonstrated that suramin has differential effects on rat prostate cancer cells in vitro. The effects of suramin on cell growth were biphasic. At low concentrations of 0.01 mM and 0.1 mM, suramin stimulated growth while it was inhibitory at a higher concentration of 1.0 mM, and 10 mM suramin resulted in cell death. Cell motility was inhibited at a suramin concentration above 0.1 mM. The inhibition of cell motility by suramin may be through the blockage of growth factor effects. Reducing serum growth factor concentration reduced cell motility and the motility was restored by the addition of basic fibroblast growth factor (bFGF) to the media. Motility which had been restored by bFGF could then be blocked by the presence of suramin. The inhibition of cell motility by suramin is reversible on washout of the drug. Suramin inhibits cell motility in both the human prostate cancer cells (LNCaP) and the rat (MLL).

Animals↗
PubMed1991

Cell motility as a chemotherapeutic target.

The major cause of failure in the treatment of patients with solid malignancies is failure to prevent or control the spread of metastases. The metastatic process is a series of interrelated steps that must be accomplished before distant tumour foci can be established. Tumour cell motility is a complex process, which is involved in many of these steps. The mechanisms by which motility is stimulated and physically generated are complex and as yet poorly understood. Viewing the cell as a chemomechanical engine that relies on a tension based system for movement allows us to design chemotherapeutic strategies to inhibit tumour cell motility directly. Chemotherapeutic agents that block stimulation, interfere with cell-ECM interactions and interfere with cytoskeletal mechanics are already being tested. Further studies will be needed to define their efficacy.

Animals↗
PubMed1990

Characterization of the subtypes of cell motility in ageing human skin fibroblasts.

Previous studies have noted alterations in cell migration during wound healing with age. Both intracellular and extracellular factors alter cell migration. In an effort to clarify the relationship between ageing and cell motility we have utilized time-lapse videomicroscopy to quantitatively and qualitatively study the various subtypes of cell motility including membrane ruffling, lamellapodal extension and cell translocation of ageing human fibroblasts in culture. We demonstrate a global decline in all types of cell motility of human fibroblasts with increasing donor age. Furthermore, we demonstrate that this decrease in cell motility with ageing is independent of chemotactic gradients.

Adult↗