Effect of Thyroid Function on MNU-Induced Mammary Carcinogenesis.

Mammary cancer is a disease that affects many women. Extensive research has been conducted to elucidate which variables are involved in the development of this cancer. Studies have highlighted thyroid function as a modulator of tumor growth and development.

Gefitinib inhibits the growth and invasion of urothelial carcinoma cell lines in which Akt and MAPK activation is dependent on constitutive epidermal growth factor receptor activation.

Purpose: Abnormally high levels of epidermal growth factor receptor (EGFR) protein are associated with advanced tumor stage/grade. The objective of this study was to evaluate the effects of the specific EGFR tyrosine kinase inhibitor gefitinib on activation of the Akt and mitogen-activated protein kinase (MAPK) pathways in human urothelial cell carcinoma (UCC) cell lines and to identify potential markers of gefitinib responsiveness in biopsy samples of UCC.

Experimental Design: Changes in markers of UCC growth and invasion after exposure to gefitinib were studied in six human UCC cell lines expressing various levels of EGFR.

Influence of the microenvironment on invasiveness of human bladder carcinoma cell lines.

To investigate the importance of the microenvironment in bladder cancer invasion, a panel of six bladder carcinoma cell lines (SD, RT112, JON, 1207, T24, and J82) was tested in both in vitro and in vivo invasion assays. Furthermore, invasiveness was correlated with the expression of components of the E-cadherin-catenin complex. The E-cadherin-negative cell lines, T24 and J82, displayed a high in vitro invasive capacity, whereas the E-cadherin-positive cell lines, SD and JON, completely lacked in vitro invasive capacity.

E-cadherin promotes intraepithelial expansion of bladder carcinoma cells in an in vitro model of carcinoma in situ.

High-grade transitional cell carcinomas (TCCs) of the urinary bladder are frequently associated with carcinoma in situ, which may replace large areas of the mucosa of the urinary tract. The invasive component of TCCs often reveals a loss of expression of the cell-cell adhesion molecule E-cadherin, but the role of E-cadherin in the development and expansion of intraepithelial neoplasia is unknown. To study the underlying mechanism of intraepithelial expansion (IEE), we have developed an IEE assay.

A comparative evaluation of various invasion assays testing colon carcinoma cell lines.

Various colon carcinoma cell lines were tested in different invasion assays, i.e. invasion into Matrigel, into confluent fibroblast layers and into chicken heart tissue.

Pathological features of glycogen storage disease type II highlighted in the knockout mouse model.

Glycogen storage disease type II (GSDII; Pompe's disease) is an autosomal recessive disease caused by lysosomal alpha-glucosidase deficiency. Skeletal muscle weakness is the most conspicuous clinical symptom of patients suffering from GSDII and skeletal muscle also is prominently involved in the knockout mouse model of this disease. Thus far, however, little detailed information has been published on the pathological changes in other mouse tissues.

Clonal growth of colorectal-carcinoma cell lines transplanted to nude mice.

It is generally assumed that tumor progression is a microevolutionary process in which increasingly aggressive clones, generated through genetic instability, emerge in an initially monoclonal lesion. The present study was undertaken to determine how rapidly a dominant clone will emerge from an initial polyclonal situation, and whether dominance of these clones is a prerequisite for the onset of metastasis. To this end, colon-carcinoma cells were infected in culture with an amphotropic retroviral vector containing the neomycin-phosphotransferase gene, which makes cells resistant to neomycin.

In vitro modulation of implantation and intraepithelial expansion of bladder tumor cells by epidermal growth factor.

A major problem in the management of bladder cancer is the high risk for recurrence of bladder tumors after transurethral resection. This has generally been attributed to the attachment and subsequent expansion of exfoliated tumor cells to the traumatized bladder wall. An in vitro cocultivation model was used to study the implantation and growth of human tumor cells in traumatized murine urothelium.

LacZ staining in paraffin-embedded tissue sections.

Femora and tibiae of rats carrying leukemia from a LacZ-marked acute promyelocytic leukemia-derived leukemic cell line (LT12NL15) were decalcified using EDTA and routinely embedded in paraffin. Sections were used to develop for the first time an immunostaining method for LacZ, employing catalyzed reporter deposition (CARD) based on the deposition of biotinylated tyramine. This method was used to study homing and adhesion of leukemic cells.

Inactivation of the HR6B ubiquitin-conjugating DNA repair enzyme in mice causes male sterility associated with chromatin modification.

The ubiquitin-conjugating yeast enzyme RAD6 and its human homologs hHR6A and hHR6B are implicated in postreplication repair and damage-induced mutagenesis. The yeast protein is also required for sporulation and may modulate chromatin structure via histone ubiquitination. We report the phenotype of the first animal mutant in the ubiquitin pathway: inactivation of the hHR6B-homologous gene in mice causes male infertility.

Immunocytochemical characterization of explant cultures of human prostatic stromal cells.

The study of stromal-epithelial interactions greatly depends on the ability to culture both cell types separately, in order to permit analysis of their interactions under defined conditions in reconstitution experiments. Here we report the establishment of explant cultures of human prostatic stromal cells and their immunocytochemical characterization. As determined by antibodies to keratin and prostate specific acid phosphatase, only small numbers (< 5%) of epithelial cells were present in primary cultures; subsequent passaging further reduced epithelial cell contamination.

Modulation of intra-epithelial expansion of human T24 bladder-carcinoma cells in murine urothelium by growth factors and extracellular-matrix components.

The high recurrence rate of bladder cancer is probably due to an efficient repopulation of the bladder by residual transformed cells after resection of the tumour. However, the regenerating capacity of the normal urothelial cells is very high. To study the balance between regenerating normal urothelium and out-growth of transformed urothelial cells, we recently developed an in vitro co-cultivation model.

Expression of growth factors and receptors during specific phases in regenerating urothelium after acute injury in vivo.

We investigated the spatio-temporal changes in RNA and protein expression of growth factors and their receptors by in situ hybridization and immunocytochemistry during regeneration after acute injury of mouse urothelium in vivo. These data were correlated with changes in morphology and proliferation during regeneration. Except for an enhanced muscular transforming growth factor-beta 1 (TGF-beta 1) and TGF-beta type II receptor expression, changes in expression patterns of growth factors or receptors were confined to the urothelium.

E-cadherin expression determines the mode of replacement of normal urothelium by human bladder carcinoma cells.

The high recurrence rate of human bladder cancer can be attributed to intraepithelial expansion of tumor cells or shedding and subsequent implantation of tumor cells elsewhere in the bladder. E-Cadherin is a calcium-dependent cell-cell adhesion molecule, and loss of E-cadherin by tumor cells is associated with increased tumor aggressiveness. Here we demonstrate that E-cadherin is also an important determinant of the mechanisms which are involved in the recurrence rate of bladder cancer.

Characterization of distinct functions for growth factors in murine transitional epithelial cells in primary organotypic culture.

Although previous studies indicate that growth factors can affect several physiological processes in epithelia, their role in the biological dynamics of transitional epithelium of the bladder is not yet established. This study investigates the functional consequences of a direct action of EGF, TGF beta, FGF-1, FGF-2, PDGF-AA, and PDGF-BB on mouse urothelium in organoid-like primary cultures. Confluent and nonconfluent cultures served as a model for intact and regenerating urothelium, respectively.

An in vitro model of urothelial regeneration: effects of growth factors and extracellular matrix proteins.

Although the cellular turnover of resting urothelium is very low, its regenerative capacity is known to be outstanding. In organotypic mouse urothelial cultures closely mimicking the differentiation and multilayering of normal urothelium, we examined the cell biological mechanisms underlying urothelial regeneration and the specific role of growth factors and several extracellular matrix (ECM) components. Exposure to epidermal growth factor (EGF) and acidic fibroblast growth factor (aFGF) and culture on laminin resulted in enhanced expansion of the urothelium.

Multiparameter analysis of primary epithelial cultures grown on cyclopore membranes.

The use of porous membranes as culture support for epithelial cells has previously been shown to cause functional differentiation of these cells mimicking an in vivo condition, in contrast to culture on plastic. The different materials of which the membranes are made also have different properties, such as transparency, rigidity, and retention of molecules. Cyclopore membranes (polyethylene terephtalate) are permeable, transparent, rigid, and have low protein retention.

Characterization of mouse urothelial cell lines in different phases of transitional-cell carcinogenesis.

Altered cellular responsiveness to growth factors is one of the factors involved in carcinogenesis. In order to study the role of growth factors in transitional-cell carcinogenesis, we established 3 urothelial cell lines from normal mouse urothelium, designated g/G, NUC-5 and NUC-I. These cell lines were studied by light and transmission electron microscopy, karyotyping, grafting in syngeneic mice, growth-factor response in vitro under serum-free conditions, and EGF receptor expression.

An in vitro model of intra-epithelial expansion of transformed urothelial cells.

Replacement of normal urothelium by pre-cancerous epithelium may explain the high recurrence rate of human bladder cancer. An in vitro model was designed in order to study the mechanisms of expansion of transformed urothelial cells at the expense of normal urothelium. For this purpose, mouse bladder explants were allowed to expand on a transparent porous membrane.

Androgen receptor expression in human tissues: an immunohistochemical study.

The cellular localization of the human androgen receptor was visualized immunohistochemically using a mouse monoclonal antibody (MAb) F39.4, directed against a fragment of the N-terminal domain of the androgen receptor. The nuclear immunoreactivity of various human tissues with F39.

The effect of Rauscher murine leukemia virus infection on the hemopoietic system of BALB/c mice. Cell proliferation and cell loss.

Cell proliferation was investigated in normal and Rauscher Leukemia Virus-infected BALB/c mice. Five days after inoculation, islands of leukemic blasts arose in the red pulp, and proliferated as shown by autoradiographic analysis after a pulse of 3H-Thymidine. These cells subsequently infiltrated the whole spleen and 3 weeks after infection about 60% of the spleen consisted of large immature erythroblast-like cells.

Epithelial regeneration of transposed intestine after high doses of X-irradiation.

The regeneration capacities of normal and transposed small bowel epithelium were compared in rats after applying high doses of X-irradiation. It has been shown that the potency of the mucosa to regenerate is much higher than assumed and that the mucosa can regenerate after single doses varying from 2000-5000 R. Even in the villus epithelium and in flat epithelium covering infiltrates of the lamina propria cells survive, which are still able to resume proliferative activity several days after irradiation.