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Biomedical subjects

M E Zeigler

Publications and source records attributed to M E Zeigler.

11 recordsLinked to original sources
PubMed1998

Elaboration of matrix metalloproteinase inhibitors by human skin in organ culture and by skin cells in monolayer culture: relationship to invasion.

Functional and immunochemical approaches were used to assess matrix metalloproteinase (MMP) inhibitors, e.g., tissue inhibitor of metalloproteinases 1 and 2 (TIMP-1 and TIMP-2), in organ cultures of normal human skin maintained under growth factor free conditions or in medium supplemented with a combination of growth factors including epidermal growth factor, insulin, and pituitary extract. It has previously been shown that under growth factor free conditions, normal skin structure and function are maintained for several days, while in the presence of these exogenous growth factors, the epithelial cells invade the stroma [Invasion and Metastasis 1993;13:225-233]. TIMP-1 was detected in equivalent amounts in organ culture fluids under both conditions. TIMP-2 was not detected under either condition. Normal epidermal keratinocytes, normal dermal fibroblasts, and three different epithelial tumor cell lines were also examined for MMP inhibitor expression. Keratinocytes and fibroblasts produced high levels of both TIMP-1 and TIMP-2, but in neither cell type was there a significant difference between growth factor free and growth factor containing conditions. In contrast, the three epithelial tumor cell lines produced low to undetectable levels of both TIMP-1 and TIMP-2. These data suggest that acquisition of local invasive capacity is not dependent on a reduction in MMP inhibitor expression. A reduction in MMP inhibitors may accompany the transition from invasive to metastatic tumors.

Blotting, Western↗
PubMed1997

Human squamous carcinoma cell invasion in organ-cultured skin.

In a previous study we showed that normal human epidermal keratinocytes were capable of invading the dermis of organ cultured skin when the tissue was treated with an exogenous source of epithelial growth factors (Fligiel and Varani (1993) Invasion Metastasis, 13, 225-233). Here we examined human squamous carcinoma cells from three different tumors for ability to invade the dermis in the same model. Invasion occurred in 40-80% of the tissues, depending on the tumor line, and was observed with equal frequency under both growth factor-free conditions and in the presence of exogenous growth factors. These data demonstrate that malignant human epithelial cells have the capacity to invade the dermis of organ-cultured skin. Unlike normal keratinocytes, there appears to be no exogenous growth factor requirement for invasion by the malignant cells.

Carcinoma, Squamous Cell↗
PubMed1996

Growth factor-induced epidermal invasion of the dermis in human skin organ culture: dermal invasion correlated with epithelial cell motility.

We have developed a model of human squamous epithelial cell invasion in human skin organ culture. Epidermal invasion of the dermis occurs in this model when the tissue is exposed to an exogenous source of epithelial cell growth factor. In the present study we sought to determine to what extent growth factor-induced invasion correlates with the ability of the growth factor to induce epithelial cell motility. Histological examination of tissue treated with epidermal growth factor (EGF), hepatocyte growth factor (HGF), insulin-like growth factor-1 (IGF-1) or keratinocyte growth factor (KGF) showed that only HGF and EGF were inducers of invasion while KGF- and IGF-1-treated tissues were histologically similar to untreated controls. In parallel studies, HGF and EGF were found to be potent stimulators of epidermal keratinocyte motility while IGF-1 was less effective and KGF was even less so. None of the growth factors stimulated dermal fibroblast motility while HGF and to a lesser extent IGF-1 (but not EGF or KGF) stimulated motility of dermal vascular endothelial cells. Thus, there is a strong correlation between growth factor capacity to induce epidermal keratinocytes to invade the underlying dermal tissue and to induce motility in the invasive population of cells.

Adult↗
PubMed1996

Growth factor-induced epidermal invasion of the dermis in human skin organ culture: expression and role of matrix metalloproteinases.

Matrix metalloproteinase activity was assessed in culture fluids of organ-cultured human skin by gelatin zymography. Both the 92-kD gelatinase/type IV collagenase and the 72-kD gelatinase/type IV collagenase were detected. Production of the 92-kD enzyme was substantially increased in the presence of epidermal growth factor (EGF) and hepatocyte growth factor (HGF) as compared to control but not in the presence of insulin-like growth factor-1 (IGF-1) or keratinocyte growth factor (KGF). This is of interest because our recent studies have shown that EGF and HGF induce the epithelial cells to invade the underlying stroma while normal architecture is maintained in the presence of IGF-1 and KGF. Addition of tissue inhibitor of metalloproteinase-2 to the organ culture fluids blocked expression of the active forms of both enzymes and concomitantly blocked invasion. Epidermal keratinocytes, dermal fibroblasts and dermal endothelial cells were grown in monolayer culture and examined for matrix metalloproteinase production. The 92-kD enzyme accounted for most of the gelatinase activity in keratinocyte culture fluids while the 72-kD enzyme accounted for most of the activity in the dermal fibroblast and endothelial cell culture fluids. Increased production of the 92-kD enzyme was seen in keratinocytes upon exposure to the growth factors that induced invasion (EGF and HGF) while the two factors that did not induce invasion (IGF-1 and KGF) were much less effective. Production of the 72-kD enzyme in fibroblasts and endothelial cells was not upregulated by any of the four growth factors. Taken together, these data indicate that matrix metalloproteinase activity is increased in the epithelium under the influence of invasion-inducing growth factors and contributes to invasion.

Cells, Cultured↗
PubMed1992

cDNA cloning and genomic analysis of a new multigene family sharing common phylogenetic and expression profiles with the laminin receptor gene.

We have isolated a human laminin receptor (LR) cDNA which bears a different sequence in its 5' end with regard to the corresponding region in the regular LR mRNA. This different sequence hybridizes to a 1 kb mRNA. We have cloned a 740 bp cDNA for this transcript (cDNA 48-1). Search on sequence data bases revealed no sequence homology with known messengers or proteins. Using cDNA 48-1 in a simplified version of the protocol with which we had previously characterized the LR gene as a member of a retrogene family in mammals, we show in the present paper that the gene of this new transcript exhibits phylogenic, expression and amplification features that strickingly recall those of the LR gene.

Amino Acid Sequence↗
PubMed1992

Posttranscriptional regulation of alpha-casein mRNA accumulation by laminin.

We have utilized primary cultures of rat mammary epithelial cells to study mechanisms by which laminin regulates the prolactin-dependent accumulation of alpha-casein mRNA. Mammary cells accumulate approximately fivefold more alpha-casein mRNA when cultured on laminin than when cultured on tissue plastic and the accumulation of alpha-casein mRNA is prolactin dependent. On the basis of transcription assays there is approximately a twofold increase in the alpha-casein mRNA transcription rate in cells cultured on laminin over that of tissue culture plastic. Measurements on the turnover of alpha-casein mRNA show that this mRNA is stabilized fourfold more on laminin than on tissue culture plastic, while there was no significant difference in the turnover of poly(A) RNA on either substratum. These data indicate that laminin regulates the cytoplasmic levels of alpha-casein mRNA accumulation primarily at the post-transcriptional level by increasing the stabilization of this mRNA.

Animals↗
PubMed1991

Genomic analysis of the 67-kDa laminin receptor in normal and pathological tissues: circumstantial evidence for retroposon features.

We have cloned two cDNAs for the human 67-kDa laminin receptor (LR). In the present report we show that these clones hybridize to many restriction fragments in Southern experiments in human. This particular pattern is accounted for by the presence of up to 16 and 21 copies of the laminin receptor gene per haploid genome in human and mouse, respectively. In contrast, a single gene copy is found in chicken. Chromosomal localization reveals four main loci: LAMRP1, laminin receptor pseudogene 1 (Chr 3); LAMRP2, laminin receptor pseudogene 2 (Chr 12); LAMRP3, laminin receptor pseudogene 3 (Chr 14); LAMRP4, laminin receptor pseudogene 4 (Chr X). Comparison of our experimental results to the known features of processed retropseudogenes enabled us to conclude that the LR gene belongs to a retroposon family in mammals.

Animals↗
PubMed1990

Protooncogene expression in normal and psoriatic skin.

The expression of the c-myc, c-fos, c-jun, c-erbB, and c-Ha-ras protooncogenes was compared by Northern blot analysis of total RNA extracted from keratome biopsies of normal skin and psoriatic plaques. Isolation of intact RNA from frozen tissue required careful attention to technique during the early stages of extraction. Densitometric analysis revealed 1.5- to 2.5-fold elevations of c-myc transcript levels in lesional psoriatic relative to normal epidermis. Similar increases in cyclophilin and lipocortin II transcripts were also observed and may reflect characteristic differences in RNA preparations from normal and psoriatic epidermis. C-myc, c-jun, c-erbB, c-fos, and c-Ha-ras transcript levels were not significantly increased in lesional psoriatic epidermis when protooncogene mRNA levels were normalized to those of the cyclophilin or lipocortin genes. In contrast, transforming growth factor-alpha (TGF-alpha) transcripts were significantly increased (10- to 20-fold) with or without prior normalization. C-myc, c-fos, and c-jun transcripts were significantly induced over in vivo levels 2-4 h after organ culture of normal or psoriatic keratome biopsies, demonstrating that these genes can be highly expressed in the context of tissue injury. Our results suggest that overexpression of these protooncogenes per se is not central to the pathogenesis of psoriatic epidermal hyperplasia.

Epidermis↗
PubMed1989

Regulation of mammary differentiation by the extracellular matrix.

In multicellular organisms cell growth and differentiation are influenced by soluble factors, cell-cell interactions and cell-extracellular matrix interactions. We have used the rat mammary gland as a model system to study the role of extracellular matrix components in the regulation of milk protein gene expression. Since mammary epithelial cells differentiate on a basement membrane in vivo, we investigated the effects of basement membrane components on the expression of the milk protein genes, alpha-casein, alpha-lactalbumin, and transferrin. We have demonstrated that a basement membrane gel, as well as its major basement membrane component, laminin, induced alpha-casein and alpha-lactalbumin expression as much as 160-fold compared to tissue culture plastic. We demonstrate that laminin affects mRNA stability as well as having an effect on protein stability and secretion. Laminin interacts with mammary epithelial cells via an 68 kD cell surface receptor which is capable of interacting with the cellular cytoskeleton. In order to provide evidence that laminin affects on mammary differentiation are mediated through this receptor via the cytoskeleton, we examined the effects of cytoskeletal disrupting agents on milk protein gene expression. We demonstrate that cytochalasin D or colchicine selectively block laminin-mediated milk protein gene expression by affecting mRNA stability. Based on these experiments, we propose a model in which laminin affects mammary gene expression through interaction with cell surface receptors which interact with the cytoskeleton resulting in stabilization of mRNAs for milk protein genes.

Animals↗
PubMed1987

Regulation of rat mammary gene expression by extracellular matrix components.

In the mammary gland the induction and maintenance of differentiation are dependent on both lactogenic hormones and the extracellular matrix (ECM). Since mammary epithelial cells differentiate on a basement membrane in vivo we have examined the effects of basement membrane components on the expression of milk protein genes in primary rat mammary cultures. We examined the effects of a basement membrane gel derived from the Englebreth-Holm-Swarm tumor as well as its major component, laminin, on the expression of a group of milk protein genes. We demonstrate that the basement membrane gel induces alpha-casein and alpha-lactalbumin (alpha-LA) accumulation up to 160- and 70-fold, respectively, of that on tissue culture plastic. Laminin, a major component of the basement membrane, also caused significant induction of these same proteins. In order to determine whether these ECM effects occurred at a translational or post-translational level, pulse-chase experiments were performed. These experiments demonstrated that a laminin substratum selectively effects milk protein turnover and secretion. In order to demonstrate whether ECM effects occurred at the level of steady state accumulation of mRNA we performed dot blot and Northern analyses using cloned cDNA probes for alpha-, beta-, and gamma-caseins and alpha-LA. These studies demonstrated that ECM components induced alpha- and beta-caseins up to 10-fold, and alpha-LA up to 3-fold, with no significant effect on gamma-casein. These results demonstrate that milk protein genes are not coordinately regulated by ECM components. Furthermore, since the amount of induction of milk proteins exceeds the amount of induction of mRNAs for these proteins, we conclude that in our system a major effect of ECM components is at the translational and/or post-translational levels. Based on these findings we propose a model in which basement membrane components effect mammary gene expression at multiple levels.

Animals↗