Regulation of DNA binding and transactivation in p53 by nuclear localization and phosphorylation.

Compelling evidence indicates that p53 acts as a transcription factor and that this activity is regulated by several factors including subcellular localization and phosphorylation status of the protein. To learn more about how these two processes determine whether p53 becomes activated, we studied the temperature sensitive murine p53, p53val135. At nonpermissive temperatures, p53val135 remains sequestered in the cytoplasm of cells which express it.

Nutritional influences on biofilm development.

The amounts and types of nutrients in the environment influence the development and final bacterial and chemical composition of biofilms. In oligotrophic environments, organisms respond to nutrient stress by alterations in their cell morphology and cell surfaces, which enhance adherence. Little is known of the responses to stress by bacteria in the animal oral cavity.

Coordinated expression of matrilysin during TPA-induced apoptosis of LNCaP cells: two parallel processes affected by TPA.

Matrix metalloproteinases (MMPs) are upregulated by growth factors and 12-O-tetradecanoyl-phorbol-13-acetate (TPA). TPA (10 nM) induced apoptosis in LNCaP cells grown in serum-free medium at high seeding density, and increased mRNA and secreted protein levels for the MMP matrilysin. While the TPA-augmented increase in matrilysin mRNA was seen at 4 h, secreted matrilysin protein levels at 8 h, TPA-induced DNA ladder formation was seen only at 10 h and the TPA-induced apoptosis was detected at 12 h.

Melanocyte mediated paracrine induction of extracellular matrix degrading proteases in squamous cell carcinoma cells.

The expression of extracellular-matrix (ECM)-degrading proteases has been shown to be necessary for invasion of tumor cells into surrounding tissue. For several tumor types, overexpression of these proteases is dependent upon interactions with adjacent fibroblast cell populations. We previously demonstrated activation of matrix metalloprotease (MMP) and urokinase-type plasminogen activator (uPa) expression in a coculture model consisting of squamous cell carcinoma cells (SCC) with dermal fibroblasts.

A human xenograft model for testing early events of epithelial neoplastic invasion.

We report on a model of human prostate tumor cell invasion using the SCID (severe combined immunodeficient) mouse diaphragm. Tumor cells were injected into SCID mice intraperitoneally and the diaphragms harvested three to five weeks later. Electron microscopy showed tumor cell penetration of the mesothelial cell layer and adhesion to the underlying basement membrane on the inferior surface of the mouse diaphragm, where colonies developed.

Effects of acute and chronic arsenic exposure of human-derived keratinocytes in an In Vitro human skin equivalent system: a novel model of human arsenicism.

An organotypic culture (OTC) of a human keratinocyte cell line (HaCaT) over a human fibroblast-embedded collagen gel was used to model human epidermis in arsenicism, a syndrome that currently lacks valid experimental models. Keratinocytes were exposed acutely or chronically to a mixture of arsenate (0.5 muM), monomethylarsonic acid (MMA; 0.

Does assessment of microbial composition of plaque/saliva allow for diagnosis of disease activity of individuals?

Microbiological tests are limited in their applicability in the assessment of caries activity and in caries prediction. They can be effective in group of persons with high or low caries experience. The reasons for the limitation of microbiological tests rests with unique characteristics of the microflora and local environments of the oral cavity, which will modify the cariogenicity of plaque in an individual.

Activation of AP-1 by okadaic acid in mouse keratinocytes associated with hyperphosphorylation of c-jun.

Okadaic acid (OA), a specific inhibitor of protein phosphatases 1 and 2A, is also a potent mouse skin tumor promoter. The effects of OA on regulation of c-jun/activator protein-1 (AP-1) transcriptional activation were investigated in mouse keratinocytes. AP-1 DNA binding to the jun 12-O-tetradecanoylphorbol-13-acetate-response element (TGACATCA) as determined by gel shift analysis was strongly induced by OA (100 ng/mL) at 6 and 12 h.

Regulation of the transcription factor AP-1 in benign and malignant mouse keratinocyte cells.

The mouse benign keratinocyte cell line 308 was previously shown to have less AP-1 DNA binding and transactivation ability than its malignant variant 10Gy5. Because elevated AP-1 activity in 10Gy5 appears to be critical for its malignant phenotype, we were interested in examining the molecular mechanisms that regulate activator protein 1 (AP-1) in this system. In both 308 and 10Gy5 cells, c-fos, fra-2, c-jun, jun B, and jun D were capable of binding to an AP-1 DNA binding site as determined by antibody clearance gel mobility shift assays.

Regulation of matrilysin expression in cells of squamous cell carcinoma by E-cadherin-mediated cell-cell contact.

A critical attribute of invasive carcinomas is their ability to degrade components of the extracellular matrix, a process achieved by the matrix metalloproteases. In the human squamous cell carcinoma cell line II-4, mRNA and protein expression of the matrix metalloprotease matrilysin was observed to be significantly higher in confluent than in log-phase growth conditions. The purpose of this study was to determine the basis for this switch in constitutive matrilysin expression.

p53 Phosphorylation: biochemical and functional consequences.

The p53 protein plays a vital role in suppressing the development of cancer. Posttranslational modification through phosphorylation has been postulated to be an important regulatory mechanism of p53 function. Data describing the role of phosphorylation in terms of its effects on several biochemical properties and cellular functions of p53 are examined in the context of how p53 might be "phospho-regulated.

Ultraviolet B-induced activated protein-1 activation does not require epidermal growth factor receptor but is blocked by a dominant negative PKClambda/iota.

The exposure of mammalian cells to UV irradiation leads to the activation of transcription factors such as activated protein-1 (AP-1) and NFkappaB. It is postulated that epidermal growth factor (EGF) receptor, but not protein kinase C (PKC), is the major membrane mediator in UV-induced signal transduction. Since UVB is responsible for most of the carcinogenic effects of sun exposure, we investigated the role of EGF receptors and PKC in UVB-induced AP-1 activation.

Quantitation of early clonal expansion of two mutant 61st codon c-Ha-ras alleles in DMBA/TPA treated mouse skin by nested PCR/RFLP.

It has been hypothesized that tumor promotion in mouse skin involves clonal expansion of initiated cells with activated c-Harvey (Ha)-ras oncogene to give rise to benign tumors. We have used the two stage mouse skin carcinogenesis model using 7,12-dimethylbenz[a]anthracene (DMBA) as the initiator and 12-O-tetradecanoyl-phorbol-13-acetate (TPA) as the tumor promoter to quantitate the number of mutated c-Ha-ras alleles in mouse epidermal DNA. Epidermal samples were harvested over a 12-week period before the appearance of papillomas.

PCR/RFLP assay for copy number of mutant and wild-type alleles.

A PCR method for quantitating the copy number of mutant vs. wild-type alleles in DNA from cell lines is described. The assay can be used to detect a point mutation in any gene that creates or destroys a restriction site.

Mutans streptococci caries and chlorhexidine.

Mutans streptococci, particularly Streptococcus mutans and Streptococcus sobrinus, can be shown to be highly associated with caries in humans. Together with Lactobacillus spp., they are regarded as significant odontopathogens.

Clonal diversity of Streptococcus mitis biovar 1 isolates from the oral cavity of human neonates.

The clonal diversity of 101 isolates of the pioneer bacterium Streptococcus mitis biovar 1 obtained from the oral cavities of 40 human neonates 1 to 3 days, 2 weeks, and 1 month postpartum was examined by using rRNA gene restriction patterns. There was a high degree of genetic diversity, with the 101 isolates comprising 93 unique PvuII ribotypes. There were eight identical pairs of ribotype patterns, and seven of the eight pairs were obtained from individual neonates.

Matrilysin expression in the involuting rat ventral prostate.

Matrilysin (PUMP-1) is a member of the matrix metalloproteinase (MMP) family of extracellular matrix degrading enzymes that has been found to be overexpressed in human prostate cancer. The rat ventral prostate (RVP) following castration has been used as a model for both tissue involution and apoptosis. Northern analysis and in situ hybridization were used to determine the time course and localization of matrilysin during 8 days of RVP involution.

Okadaic acid stimulated TRE binding activity in a papilloma producing mouse keratinocyte cell line involves increased AP-1 expression.

The effects of the non-phorbol ester type tumor promoter okadaic acid, a serine-threonine phosphatase inhibitor, on activator protein 1 (AP-1) DNA binding activity were studied in papilloma producing 308 mouse keratinocytes. Okadaic acid increased AP-1 binding to a consensus TPA responsive element (TRE) within 2 h; maximum stimulation was observed at 6 h followed by a gradual decrease to basal levels within 24 h. Jun B, Jun D and Fos B proteins were identified as the major components of the AP-1 complex binding to the TRE element at 6 h.

Detachment of Streptococcus mutans biofilm cells by an endogenous enzymatic activity.

Previous studies have shown that Streptococcus mutans NG8 possesses an endogenous surface protein-releasing enzyme (SPRE) activity that liberates its own surface proteins (S. F. Lee, Infect.

Mapping of the metalloproteinase gene matrilysin (MMP7) to human chromosome 11q21-->q22.

The matrix metalloproteinase, matrilysin, is thought to play an important role in the early steps of tumor progression. We determined the chromosome location of the matrilysin gene (MMP7) by Southern and PCR analysis of two different panels of somatic cell hybrids and in situ hybridization of metaphase chromosomes. Matrilysin maps to the region, 11q21-->q22, adding MMP7 to the cluster of matrix metalloproteinase genes that have already mapped to this region.

Matrilysin expression in human prostate carcinoma.

The metalloproteinases, a multigene family of metal-requiring enzymes, have been suggested to play a role in tumor invasion and metastasis. Previously, we demonstrated that human primary prostate tumors express higher levels of matrilysin and gelatinase A mRNA than normal prostate does. In the study presented here, we used in situ hybridization and immunohistochemical staining of serial sections of paraffin-embedded primary prostate tumors to compare the sites of matrilysin and gelatinase A expression and protein localization.

Degradation of fibronectin fibrils by matrilysin and characterization of the degradation products.

Matrilysin is a metalloproteinase expressed in a variety of tumors as well as in some types of normal tissue. In addition to regulating normal tissue remodelling, metalloproteinases are believed to play a role in tumor cell invasion and metastasis by degrading components of the extracellular matrix, for example the highly insoluble fibronectin fibrils found in the interstitial stroma. In this study we examined whether matrilysin can degrade fibronectin fibrils produced by human foreskin fibroblasts and characterized the degradation products of soluble fibronectin.