PubMed Health⌕ Search

Biomedical subjects

B E Elliott

Publications and source records attributed to B E Elliott.

At least 19 recordsLinked to original sources
PubMed2006

A novel activating function of c-Src and Stat3 on HGF transcription in mammary carcinoma cells.

In the normal breast, hepatocyte growth factor (HGF) is primarily expressed by stromal cells, and stimulates in a paracrine manner epithelial cells expressing the HGF receptor (Met). In invasive human breast carcinomas, HGF and Met are frequently overexpressed, possibly establishing an autocrine HGF/Met loop that promotes tumour cell invasion. However, the mechanisms leading to autocrine HGF expression in carcinoma cells are not known. We previously demonstrated a cooperative effect between c-Src and Stat3 in the activation of HGF transcription in mammary carcinoma cells. The present report defines a novel Stat3 consensus site at nt -95 in the HGF promoter that is highly conserved in human and mouse, and is required for c-Src and Stat3 to activate HGF transcription in breast epithelial cells. DNA-protein binding studies demonstrated high affinity binding of a Stat3-containing complex to the nt -95 site. Endogenous Stat3 binding to this region of the HGF promoter in carcinoma cells expressing HGF was demonstrated using a chromatin immunoprecipitation assay. In addition, coexpression of Stat3 and activated c-Src caused increased expression of endogenous HGF mRNA and protein and marked cell scattering in breast epithelial cells. Our results delineate a novel c-Src/Stat3-dependent mechanism that regulates HGF promoter activity, and is linked to transformation of mammary epithelial cells.

Animals↗
PubMed2005

Src-dependent ezrin phosphorylation in adhesion-mediated signaling.

In addition to providing a regulated linkage between the membrane and the actin cytoskeleton, ezrin participates in signal transduction pathways. Here we describe that expression of the ezrin Y145F mutant delays epithelial cell spreading on fibronectin by inhibiting events leading to FAK activation. The defect in spreading was rescued by the overexpression of catalytically functional Src. We demonstrate that ezrin Y145 is phosphorylated in A431 cells stimulated with epidermal growth factor (EGF) and in v-Src-transformed cells. Moreover in cells devoid of Src, SYF-/- fibroblasts, ezrin Y145 phosphorylation could only be detected upon the introduction of an active form of Src. The phosphorylation of ezrin at Y145 required prior binding of the Src SH2 domain to ezrin. Our results further show that Src activity influences its binding to ezrin and a positive feedback mechanism for Src-mediated Y145 phosphorylation is implied. Interestingly, cells expressing ezrin Y145F did not proliferate when cultured in a 3D collagen gel. Collectively, our results demonstrate a key signaling input of Src-dependent ezrin phosphorylation in adhesion-mediated events in epithelial cells.

Actins↗
PubMed2000

Osteopontin-induced, integrin-dependent migration of human mammary epithelial cells involves activation of the hepatocyte growth factor receptor (Met).

Osteopontin (OPN) is a secreted glycophosphoprotein which induces migration of mammary carcinoma cells, and has been implicated in the malignancy of breast carcinoma. Hepatocyte growth factor (HGF) induces cell migration of several mammary epithelial cell (MEC) lines, via activation of its cognate receptor (Met). This study examines the mechanism of OPN-induced MEC migration, in terms of the cell surface integrins involved and induction of the HGF/Met pathway. Three different MEC cell lines were used, representing different stages of tumor progression: 21PT, non-tumorigenic; 21NT, tumorigenic; non-metastatic; and MDA-MB-435, tumorigenic, highly metastatic. Human recombinant OPN was found to induce the migration of all three lines. OPN-induced migration of 21PT and 21NT cells was alphavbeta5 and beta1-integrin dependent, and alphavbeta3-independent, while that of MDA-MB-435 cells was alphavbeta3-dependent. HGF also induced migration of all three cell lines, and a synergistic response was seen to HGF and OPN together. The increased migration response to OPN was found to be associated with an initial increase in Met kinase activity (within 30 min), followed by an increase in Met mRNA and protein expression. OPN-induced cell migration is thus mediated by different cell surface integrins in MEC lines representing different stages of progression, and involves activation of the HGF receptor, Met.

Blotting, Northern↗
PubMed2000

Specific inhibition of growth factor-stimulated extracellular signal-regulated kinase 1 and 2 activation in intact cells by electroporation of a growth factor receptor-binding protein 2-Src homology 2 binding peptide.

Activation of the Ras pathway is central to mitogenesis by a variety of growth factors such as the epidermal growth factor, platelet-derived growth factor, or hepatocyte growth factor. Ras activation requires the function of adaptors such as growth factor receptor-binding protein 2, which can bind either directly or indirectly through Src homology 2 domains to the activated receptor. To examine the role of the Src homology 2 domain of growth factor receptor-binding protein 2 in the mitogenic response triggered by these growth factors, we introduced a peptide (PVPE-phosphono-methylphenylalanine-INQS) that can selectively bind this domain into mouse, rat, or human cells growing on conductive indium-tin oxide-coated glass by in situ electroporation. Cells were subsequently stimulated with growth factors and assessed for activation of a downstream target, extracellular signal-regulated kinase (ERK) 1/2, by probing with antibodies specific for its activated form. Electrodes and slides were configured to provide nonelectroporated control cells side by side with the electroporated ones, both growing on the same type of indium-tin oxide-coated glass surface. The data demonstrate that the peptide can cause a dramatic inhibition of epidermal growth factor or platelet-derived growth factor-mediated ERK1/2 activation and DNA synthesis in vivo, compared with its control phenylalanine-containing counterpart. In contrast, the peptide had a very limited effect on hepatocyte growth factor-triggered ERK1/2 activation and DNA synthesis. These results demonstrate the potential of the in situ electroporation approach described here in the study of the coupling of activated receptor tyrosine kinases to the ERK1/2 cascade.

3T3 Cells↗
PubMed1999

Characterization of a functional relationship between hepatocyte growth factor and mouse bone marrow-derived mast cells.

During the early stage (at 4 weeks) of interleukin-3 (IL-3)-induced development, mouse bone marrow-derived mast cells (BMMC) express alpha 4, alpha 5 and alpha 6 integrins, whereas with further maturation beyond 10 weeks, only alpha 5 integrin remains stably expressed. Hepatocyte growth factor (HGF) modulates the growth and movement of diverse cell types upon binding to its receptor, encoded by the proto-oncogene c-met. We report here the expression of c-met by BMMC throughout the course of their development. In addition, HGF stimulated migration of early week-4 BMMC, but not of the later stage week-10 BMMC, on fibronectin and laminin substrates. The developmental stage-dependent effect of HGF on BMMC was due to specific stimulation of the migratory function of alpha 4 and alpha 6, but not alpha 5 integrins. In addition, HGF had no effect on BMMC growth, either alone or in combination with IL-3. While HGF is stimulatory of the migratory function of BMMC, our results show that BMMC in turn can modulate HGF function. Thus, upon activation via the IgE receptors, BMMC released proteases that abolished HGF activities. Analyses of the degradation products by two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis and Western blot using antisera prepared against recombinant HGF and the kringle 3 domain of HGF revealed specific degradation of HGF alpha but not beta/beta' subunits. Therefore, our results suggest that: 1) the motogenic effect of HGF on BMMC varies according to the stage of their development, 2) HGF stimulation of BMMC migration is due to selective activation of alpha 4 and alpha 6, but not alpha 5 integrin function, and 3) there exists a two-way relationship between BMMC and HGF such that HGF stimulates the beta 1 integrin-mediated migratory function of BMMC, which can, in turn, modulate HGF function by release of serine proteases.

Animals↗
PubMed1997

The experiences of mothers caring for a child with severe atopic eczema.

Atopic eczema is a relatively common disease which frequently occurs during childhood. This paper reports the findings of a research study which explored the effects upon family life of caring for a child with severe atopic eczema. Seventy-seven accounts written by mothers of preschool children with this disease were analysed using qualitative latent content analysis. The focus of this paper is on the implications of the disease for the mothers' role and the additional work generated by the disease. The implications of these findings for nursing practice, in particular the work of health visitors and paediatric community nurses, is discussed. Throughout this paper the term 'nurse' is used to describe both nurses and health visitors.

Adaptation, Psychological↗
PubMed1997

The role of integrins and extracellular matrix in anchorage-independent growth of a mammary carcinoma cell line.

Anchorage-independent growth is a property of malignant cells. Extracellular matrix proteins are present in tumor spheroids but their function is not clearly defined. In this paper we show that a murine mammary carcinoma cell line, SP1, which expresses the fibronectin receptor alpha 5 beta 1 requires fibronectin for anchorage-independent growth in soft agar. Growth factors (hepatocyte growth factor and transforming growth factor-beta) also promote SP1 colony growth. In contrast, collagen types I and IV have an inhibitory effect on SP1 colony growth. A clone isolated from SP1 cells which expresses the collagen/laminin receptor alpha 2 beta 1 as well as the fibronectin receptor alpha 5 beta 1, demonstrates increased colony formation in the presence of fibronectin and collagen. These data suggest a role for both the alpha 5 beta 1 and alpha 2 beta 1 integrin receptors in the regulation of anchorage-independent growth of mammary carcinoma cells.

Animals↗
PubMed1996

Coexpression of hepatocyte growth factor and receptor (Met) in human breast carcinoma.

Expression of hepatocyte growth factor (HGF) and HGF receptor (HGFR, product of the met proto-oncogene) mRNA were examined by nonisotopic in situ hybridization in a spectrum of benign and malignant human breast tissues. mRNA for both HGFR and HGF was detected in benign ductal epithelium. Epithelial expression of HGF mRNA was particularly intense in regions of ductal epithelial hyperplasia. Positive expression of HGF (but not HGFR) mRNA was also found in adipocytes, endothelial cells, and to varying degrees in stromal fibroblasts. In 12 of 12 cases of ductal carcinoma in situ and infiltrating ductal carcinoma, carcinoma cells showed a heterogeneous pattern of expression for both HGFR and HGF mRNA. In infiltrating ductal carcinomas, intense expression of HGFR mRNA was not restricted to ductular structures but as also seen in non-duct-forming carcinoma cells. The same zones of the tumors (most commonly at the advancing margins) that expressed strongly HGFR mRNA often were also strongly positive for HGF mRNA, suggesting a possible autocrine effect. The expression pattern of HGFR protein in 25 cases including the same series of tissues used for in situ hybridization analysis was similar to that of HGFR mRNA, as determined by an immunoperoxidase technique. The finding that HGFR is expressed by both benign and malignant epithelium, and its not restricted to duct-forming structures, suggests that, although the potential for HGF/HGFR binding is maintained in malignancy, the response to ligand binding at the level of the receptor or the cellular response to receptor activation may change at some point during progression.

Breast↗
PubMed1994

Anti-beta 1 integrin IgG inhibits pulmonary macrometastasis and the size of micrometastases from a murine mammary carcinoma.

In the present report, we investigated the possible importance of beta 1 integrins in the growth and metastasis of a murine mammary carcinoma, SP1, and a metastatic variant, SP1-3M in vivo. CBA/J female mice bearing SP1 tumor transplants were injected with anti-beta 1 integrin IgG or control nonimmune IgG (200 micrograms per mouse; i.p.) every two days. Animals received anti-CD4 antibody (100 micrograms per mouse) at time zero to suppress immunity against rabbit IgG. Outgrowth of macroscopic metastases from SP1, but not from SP1-3M primary tumors, was markedly inhibited in animals receiving anti-beta 1 integrin IgG but not nonimmune IgG. To assess the stage(s) in the metastatic cascade affected, we examined the number and diameter of micrometastatic nodules in treated and untreated groups. The diameter of micrometastases was significantly reduced in SP1-tumor-bearing mice treated with anti-beta 1 integrin IgG compared to control IgG, although the number of nodules per cm2 of lung sections examined remained unchanged. No change in the number or size of micrometastases in SP1-3M tumor-bearing mice was observed. No difference in the binding, or complement-mediated and antibody-dependent cell-mediated cytotoxicity of anti-beta 1 integrin IgG with SP1 and SP1-3M cells was detected. The results suggest that under these conditions anti-beta 1 integrin inhibits metastatic tumor growth in lung tissue, but has minimal effect on intravasation, adhesion to target organs and extravasation.

Animals↗
PubMed1992

Capacity of adipose tissue to promote growth and metastasis of a murine mammary carcinoma: effect of estrogen and progesterone.

Previously we have shown that a murine mammary carcinoma cell line, designated SPI, grows and metastasizes more efficiently in the mammary gland than in the subcutis. In this report, we examine the tissue specificity of this phenomenon. Our results show that SPI cells grow best in the mesenteric and ovarian fat pads and well in the mammary gland, but very poorly in the subcutis or peritoneal cavity. Massive dissemination of tumors from the ovarian and mesenteric sites occurs to the liver, spleen and diaphragm. In contrast, metastases from the mammary site occur primarily in the lung. Co-transplantation of a threshold number of SPI cells with mammary or ovarian fat fragments into the subcutis results in increased tumor growth, whereas very few tumors form in sham controls receiving no fat fragments. Removal of the ovaries of donor and recipient mice abrogates tumor growth in adipose tissue transplants. Estrogen can stimulate growth of SPI in adipose tissue sites, whereas progesterone inhibits growth. In contrast, in vivo growth of a stable metastatic variant selected from SPI cells was not inhibited by progesterone. SPI cells growing in ovarian and mesenteric fat pads showed increased expression of estrogen receptors and progesterone receptors, as well as detectable levels of epidermal-growth-factor receptors, whereas receptor levels decreased to baseline on tumors in the subcutis. The levels of estrogen-receptor mRNA reflect the corresponding functional expression of receptors; this finding suggests that the regulation of estrogen-receptor expression in this system is, at least in part, at the mRNA level. Our results are consistent with the model that adipose tissue exerts an estrogen-dependent positive regulatory effect on primary SPI tumor growth, and promotes the formation of metastases.

Adipose Tissue↗
PubMed1992

Karyotypic evolution of a murine mammary adenocarcinoma in vitro and during progression from primary to metastatic growth in vivo.

We have previously described a murine mammary tumor cell line (SP1) that metastasizes when transplanted into the mammary gland, but not when injected into the subcutaneous site. We used cytogenetic markers to assess genetic heterogeneity, and to monitor the selection and evolution of karyotypically distinct cell types during primary tumor growth and in metastases. The SP1 tumor cells are hypotetraploid (mean chromosome number = 72), and have at least four karyotypically distinct cell types. We found no consistent pattern of selection of tumor cell types in primary tumors. However, metastases were derived from a cell type that was present in the corresponding primary tumor. In addition, novel, karyotypically distinct cell types also appeared in the metastatic nodules. Markers that appeared in metastases included two translocations, t(10;18) and t(1;19). By injecting a mixture of cells from a metastatic nodule with a non-metastatic clone into mice, we showed that the new cell types in metastases displayed a stable increased growth and metastatic potential when compared to the non-metastatic clone, or when compared to the initial cell type from which the metastases derived. These results indicate that metastases are derived from a distinct cell type in the primary tumor, but that additional chromosome and cell evolution occurs, resulting in new cell types that are selected in metastases.

Adenocarcinoma↗
PubMed1991

Outgrowth of stable class I major histocompatibility complex-expressing subsets from immunogenic variants of a murine mammary carcinoma: association with a differentially staining region on chromosome 9.

We have examined interactions among intratumor subpopulations during the rejection of immunogenic variants of a murine mammary carcinoma (SPI) and in the outgrowth of tumorigenic "revertant" subsets. Analysis of subclones isolated during the early phase of rejection of one immunogenic variant revealed extensive cellular heterogeneity of tumor-forming ability and class I major histocompatibility complex (MHC) expression. Two main categories of subclones were identified. One set expressed high levels of class I MHC (MHCH) and grew poorly or not at all in normal syngeneic mice. The second set of clones expressed generally low levels of class I MHC (MHCL) and exhibited progressive growth in vivo, similar to the parent tumor. The steady-state mRNA levels for class I MHC and beta 2-microglobulin were constitutively elevated in MHCH clones compared to MHCL clones or the parent tumor. However, in vivo tumorigenic outgrowths from immunogenic variants always expressed the MHCH phenotype. A cytogenetic analysis was carried out to determine the clonal origin and lineage relationship of in vivo selected tumor outgrowths. Surprisingly, tumor outgrowths from mixtures of karyotypically distinct MHCH and MHCL subclones were derived from one lineage within the MHCH subset, despite the fact that MHCH subclones exhibited slower growth in vivo than MHCL subsets when analyzed individually. These results suggest that in polyclonal populations the various subsets sometimes interact in a way that overrides the influence of immunogenic and MHC phenotypes of individual subclones.

Adenocarcinoma↗
PubMed1991

Differential growth inhibition and enhancement of major histocompatibility complex class I antigen expression by interferons in a small-cell lung cancer cell line and its doxorubicin-selected multidrug-resistant variant.

Expression of class I and class II major histocompatibility complex antigens on a human small-cell lung cancer cell line and its multidrug-resistant variant was examined before and after exposure to interferon alpha (IFN alpha) and IFN gamma by flow cytometry. Neither IFN alpha nor IFN gamma induced class II antigen expression on the drug-sensitive or resistant cell line. Induction of class I antigen expression along with an inhibition of proliferation was observed in both cell lines after IFN alpha treatment. On the other hand, IFN gamma treatment resulted in growth inhibition and enhancement of class I antigen expression in the sensitive cell line but not the resistant cell line. The differential response of the two cell lines to IFN gamma cannot be directly attributed to the acquisition of drug resistance but it suggests that further investigation of the possibility that drug-sensitive and resistant small-cell lung tumors may respond differently to immunotherapies that include IFN gamma is warranted.

Carcinoma, Small Cell↗
PubMed1991

Capacity of CD8+ T cells to reject immunogenic variants of a spontaneous murine carcinoma: lack of non-specific (NK1.1+) effector mechanisms.

Class I MHC-expressing (Ia-) immunogenic (imm +) variants, which elicit a strong syngeneic host immune rejection response, can be isolated following 5-azacytidine treatment from the MHC-negative non-immunogenic (imm-) murine carcinoma cell line SP1 (10.1 subclone). In the present study, we have shown that CD4-depleted CD8+ T cells are both necessary and sufficient for the rejection process. Treatment of semi-syngeneic B6 X CBA F1 mice with anti-NK1.1 antibodies had no effect on the rejection of immunogenic variants, although the splenic NK (natural killer) activity of recipients was fully abrogated. Thus NK1.1+ effectors, which include most NK and LAK (lymphokine activated killer) cells, are most likely not involved in the rejection process. This finding was supported by a complete lack of NK susceptibility of SP1 cells in vitro, although variable killing by LAK and poly-I: C-induced killer cells was observed. To assess the role of NK1.1-LAK and other non-T killers (e.g. cytolytic macrophages) in vivo, we determined the specificity of the rejection process. We examined the ability of immune animals to reject a mixture of non-immunogenic parent tumour cells (or cells of an unrelated syngeneic tumour) and of the variant tumour cells used for the initial immunization. Growth of the parent tumour cells was unaffected while the same animals rejected the immunogenic tumour cells. Our findings support a primary role of tumour-specific CD8+ T cells in the rejection of imm+ variants with no detectable involvement of non-specific effector cells in the tumour destruction process.

Adenocarcinoma↗
PubMed1989

Different class I antigen oligosaccharides on a murine tumor and a lectin-resistant variant are not responsible for the differential recognition of the tumors by CTL.

Previous studies have shown that whereas a highly malignant mouse cell line termed MDAY-D2 (d haplotype) does not elicit a detectable response by cytotoxic T lymphocytes (CTL) in DBA/2 mice, strong anti-tumor CTL are generated against a wheat-germ-agglutinin-resistant variant, designated MDW3. Additional evidence suggests these anti-MDW3 CTL may not be a consequence of a unique antigenic determinant on the variant cells. Because MDW3 cells are expected to differ from MDAY-D2 cells in their surface carbohydrate structures (due to their lectin resistance) and Class I major histocompatibility molecules play a crucial role in CTL-mediated responses, we speculated that the Asn-linked oligosaccharides present on Class I molecules of MDAY-D2 and MDW3 might be different and could potentially influence recognition analyses and Con A-Sepharose affinity chromatography clearly demonstrated that the oligosaccharides isolated from the H-2Dd molecule of MDAY-D2 cells are larger and more highly branched than those of the MDW3 variant. Taken together with the finding that anti-MDW3 CTL are restricted by H-2Dd, these results suggested that the larger H-2Dd oligosaccharides on MDAY-D2 cells could potentially mask or perturb determinants required for recognition by these CTL. To test this postulate, the surface Class I oligosaccharides of both MDAY-D2 and MDW3 cells were converted to simpler hybrid structures by treatment with the oligosaccharide processing inhibitor, swainsonine. However, no effect was observed on the lysis or binding of either MDAY-D2 or MDW3 cells by anti-MDW3 CTL. Thus, the results do not support the possibility that the larger H-2Dd oligosaccharides on MDAY-D2 cells are, in themselves, responsible for the poor recognition of the parent tumor by anti-MDW3 CTL. Our data do indicate, however, that CTL target binding and effector functions are not dependent on the fine structure of complex Asn-linked carbohydrates present on Class I molecules and possibly on other, accessory molecules at the target cell surface, since MDW3 cells maintained their sensitivity to lysis by CTL following swainsonine treatment.

Alkaloids↗
PubMed1989

Failure of expression of class I major histocompatibility antigens to alter tumor immunogenicity of a spontaneous murine carcinoma.

We have shown previously that clonal immunogenic variants of murine mammary adenocarcinoma 10.1 can be isolated after treatment in vitro with the DNA-hypomethylating agent 5-azacytidine (5-aza). Such immunogenic variants frequently express elevated class I major histocompatibility complex antigens relative to the level of expression in the parent tumor and are rejected in syngeneic mice by a T-cell-dependent process. To ascertain whether elevated immunogenicity is a function of increased class I antigen expression, we isolated high class I antigen expressors from 5-aza-treated 10.1 cells by using the fluorescence-activated cell sorter. Clonal variants displaying any increase in class I antigen expression were more efficient stimulators of allo-class I antigen-specific cytolytic T-cell precursors. However, these variants displayed unaltered tumorigenicity in immunocompetent syngeneic mice. Thus, phenotypic changes other than, or in addition to, elevated class I antigen expression cause the reduced tumorigenicity of immunogenic clones of 10.1 cells isolated after 5-aza treatment.

Adenocarcinoma↗