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C Dickson

Publications and source records attributed to C Dickson.

At least 55 records · Page 3Linked to original sources
PubMed1995

Receptor binding and mitogenic properties of mouse fibroblast growth factor 3. Modulation of response by heparin.

fgf3 has been implicated in the embryonic and fetal development of the mouse and as an oncogene in murine breast cancer. We describe a procedure to purify the product of the mouse fgf3 gene and show it to be a potent mitogen for some epithelial cell lines. Using a receptor binding competition assay, Fgf3 was shown to bind with high affinity to the IIIb isoforms of Fgf receptor (FgfR) 1 and FgfR2 (ID50 = approximately 0.8 nM) and with a lower affinity to the IIIc variant of FgfR2 (ID50 = approximately 9 nM). No competition for the binding of 125I-Fgf1 was observed for FgfR1 (IIIc), FgfR3 (IIIb and IIIc), or FgfR4. Mitogenicity assays using BaF3 cells containing individual Fgf receptors showed a pattern of response in agreement with the receptor binding results. A comparison of two mammary epithelial cell lines showed a marked difference of potency and dependence upon heparin in their response to mouse Fgf3, suggesting a complex interaction between the ligand and its low and high affinity receptors.

3T3 Cells↗
PubMed1995

Mice lacking cyclin D1 are small and show defects in eye and mammary gland development.

Using homologous recombination, mice lacking cyclin D1 were generated by replacing most of the first exon of the Cyl-1 gene with sequences encoding neomycin resistance. Cyl-1(-1-) mice were viable and fertile but consistently smaller than their heterozygous or wild-type littermates. The nullizygous animals also showed two distinctive abnormalities: a severe retinopathy caused by impaired development of all layers of the retina and, in the mammary gland during pregnancy, a marked reduction in acinar development accompanied by a failure to lactate. Approximately 50% of animals also had a malformation of the jaw that manifested itself as a misalignment of the incisor teeth. Mouse embryo fibroblasts isolated from 14 day nullizygous, heterozygous, or wild-type embryos and grown under standard conditions showed similar cell-cycle and growth characteristics. Thus although cyclin D1 kinase activity may facilitate G1 progression, it is not essential for the development of most tissues and organs, and only a few specialized cell lineages are demonstrably sensitive to its absence.

Animals↗
PubMed1995

A role for FGF-8 in the initiation and maintenance of vertebrate limb bud outgrowth.

BACKGROUND: The outgrowth of the vertebrate limb bud is the result of a reciprocal interaction between the mesenchyme and a specialized region of the ectoderm, the apical ectodermal ridge (AER), which overlies it. Signals emanating from the AER act to maintain the underlying mesenchyme, called the progress zone, in a highly proliferative and undifferentiated state. Removal of the AER results in the cessation of limb bud growth, thus causing limb truncation. The best candidates for this AER-derived signal are members of the fibroblast growth factor (FGF) family, in particular FGF-4, which can maintain limb bud outgrowth following removal of the AER. However, FGF-4 is only expressed after considerable outgrowth has occurred and a well-developed limb bud has formed, and then only in the posterior part of the AER. Likewise, the other FGFs studied to date are not candidates for this activity. RESULTS: We report evidence that a recently identified member of this family, FGF-8, is expressed in the ectoderm of the prospective limb territory prior to morphological outgrowth of the limb bud in both mouse and chick. Thereafter, expression is maintained throughout the AER during limb development. We have produced and purified the FGF-8 protein, and shown that it will substitute for the AER in maintaining limb bud outgrowth in mouse embryos from which the AER has been surgically removed. FGF-8 does not, however, maintain expression of the sonic hedgehog gene. CONCLUSIONS: These results indicate that FGF-8 is an AER-derived mitogen that stimulates limb bud outgrowth. Moreover, our data suggest that FGF-8 may also be an ectodermally derived mitogen that stimulates the onset of limb bud outgrowth (budding) in the absence of a morphological AER, and indicate the possible involvement of FGF-8 in the establishment of the limb field.

Amino Acid Sequence↗
PubMed1995

Fibroblast growth factor (FGF) 3 from Xenopus laevis (XFGF3) binds with high affinity to FGF receptor 2.

We demonstrate that purified fibroblast growth factor (FGF) 3 from Xenopus laevis (XFGF3) activates the mitogen-activated protein kinase pathway and induces DNA synthesis in quiescent cells. To characterize the high affinity cell surface receptors that mediate these responses, the ligand binding domains of different FGF receptors (FGFR) were expressed on COS-1 cells, and their affinity for XFGF3 was determined. Unlabeled XFGF3 efficiently competed with 125I-FGF1 for binding to the IIIb and IIIc isoforms of FGFR2, giving 50% displacement (ID50) at 0.3-0.8 nM. Higher XFGF3 concentrations were needed to displace 125I-FGF1 from FGFR3 and FGFR1 (ID50 approximately 4 and 21 nM, respectively), indicating that XFGF3 has a lower affinity for these receptors. No association of XFGF3 with FGFR4 was found using this assay. FGFR2 isoforms isolated from both mouse and Xenopus showed similar high affinity binding of XFGF3 as determined by direct binding assays (Kd values in the range of 0.2-0.6 nM). These results indicate that the binding specificity of XFGF3 is different from that of other FGFs, and identifies FGFR2 as its high affinity receptor.

Amino Acid Sequence↗
PubMed1995

Amplification of chromosome band 11q13 and a role for cyclin D1 in human breast cancer.

In this paper we describe how research on the mouse mammary tumor virus model of breast cancer resulted in the identification of an amplified region of DNA on human chromosome 11 band q13. This amplification occurs in approximately 15% of primary breast cancers. Several candidate oncogenes map within the amplicon but by analysing expression of these genes a strong case can be made for a role for cyclin D1 in tumorigenesis. Immunohistochemical staining indicates that cyclin D1 is expressed at elevated levels in around 40% of breast cancers, including those with the 11q13 amplification. The potential function of cyclin D1 as a regulator of early cell division cycle events would be consistent with a role in neoplasia.

Blotting, Southern↗
PubMed1995

Genomic organization of the mouse cyclin D1 gene (Cyl-1).

To determine the genomic organization of the mouse cyclin D1 locus (Cyl-1), a series of cosmids and cDNAs were recovered by hybridization with a genomic probe representing the 5' end of the homologous human gene, CCND1. Primer extension indicated that transcripts originate from one of three adjacent nucleotides at a single start site. Two overlapping cDNA clones that essentially accounted for the complete sequence of the larger 4.0-kb Cyl-1 transcript were characterized. A combination of RNase protection and sequencing across intron-exon boundaries established that the gene is organized into five coding exons with a long 3' untranslated region. Repeated attempts to isolate clones corresponding to the minor 3.5-kb RNA were compromised by the presence of an internal poly(A) domain. However, hybridization with specific probes revealed that the minor transcript lacks approximately 800 nucleotides from the 3' end of the major transcript and may be generated by a novel mechanism or by RNA processing.

Amino Acid Sequence↗
PubMed1995

Chromosome 11q13 markers and D-type cyclins in breast cancer.

One in six primary human breast cancers has DNA amplification centered on the cyclin D1 gene (CCND1) on chromosome 11q13. This genetic abnormality is preferentially associated with estrogen-receptor positive tumors and may define a sub-class of patients with an adverse prognosis. Although CCND1 has the credentials of a cellular oncogene, being a target for chromosomal translocation and retroviral integration, the 11q13 amplicon encompasses several other markers and CCND1 is not the only candidate for the key gene on the amplified DNA. To assess their relative importance, we have constructed a physical map of the amplified DNA and compared the extent and frequency of amplification across the region. Since it is likely that the gene providing the selective force for amplification will be expressed at elevated levels, we have also examined expression of both RNA and protein. By these criteria, cyclin D1 remains the strongest candidate for the key oncogene on the amplicon and we are currently investigating the functional consequences of its over-expression.

Breast Neoplasms↗
PubMed1995

Preoperative control of a ruptured anastomotic femoral "pseudoaneurysm" by balloon catheter: a combined radiologic and surgical approach.

Inflow control of a rapidly expanding or ruptured femoral anastomotic "pseudoaneurysm" can be fraught with hazard. Occlusion of an anastomotic femoral aneurysm with a balloon catheter offers the surgeon a simple method of gaining inflow control prior to surgery. After achieving inflow control with the balloon catheter, the surgeon can incise the anastomotic aneurysm without significant blood loss, control back bleeding with balloon occlusion catheters, and with relative ease and safety repair or replace the anastomotic aneurysm as indicated. An illustrative case is presented.

Anastomosis, Surgical↗
PubMed1995

Nucleolar association of fibroblast growth factor 3 via specific sequence motifs has inhibitory effects on cell growth.

The dual subcellular fate of fibroblast growth factor 3 (FGF3) is determined by the competing effects of amino-terminal signals for nuclear localization and secretion (P. Kiefer, P. Acland, D. Pappin, G. Peters, and C. Dickson, EMBO J. 13:4126-4136, 1994). Mutation analysis has implicated additional basic domains in the carboxy-terminal region of the protein as necessary for nuclear uptake and the association of FGF3 with the nucleoli. Immunogold electron microscopy shows that FGF3 is predominantly within the dense fibrillar component of the nucleolus. A form of FGF3 that localizes exclusively in the nucleus and nucleolus was generated by removing signals for secretion, and expression of this nonsecreted FGF3 in a mammary epithelial cell line resulted in slowly growing colonies of enlarged cells. Thus, nuclear import and nucleolar association of FGF3 are determined by the concerted interaction of several distinct motifs, and the exclusive production of the nuclear isoform can inhibit DNA synthesis and cell proliferation.

Amino Acid Sequence↗
PubMed1995

Multiple roles for FGF-3 during cranial neural development in the chicken.

FGF-3 has been implicated in the development of the hindbrain and otocyst in vertebrate embryos. Since the chicken embryo offers a favourable system in which to study the development of these structures, we have isolated and characterised cDNAs for chicken Fgf-3 and determined its pattern of expression in chick embryos from stage 3 (primitive streak) to stage 25 (early organogenesis). Within the developing cranial neural tube, Fgf-3 exhibits dynamic spatial and temporal expression. During extension of the head process, RNA is detected in the midline of the developing neural plate. In neurulating embryos, transcripts are observed initially in rhombomeres 4 and 5 of the hindbrain and later, in rhombomere 6. During hindbrain development, expression is lost from these rhombomeres, but becomes restricted to rhombomere boundaries, providing an intracellular marker which distinguishes a population of cells within boundary regions. Fgf-3 expression is elevated in ventral and medial boundary regions and is greatly reduced in dorsal parts. Studies of regenerating rhombomere boundaries show that Fgf-3 expression is induced in reforming boundaries when even-numbered rhombomere tissue is grafted next to odd, but not when like is juxtaposed to like. Fgf-3 disappears from boundary regions just prior to the loss of the morphological boundaries suggesting a boundary-associated function. Other sites of expression have also been identified. At early stages of development Fgf-3 is expressed in the epiblast and mesendoderm of the primitive streak, in mesoderm lateral to the streak and in Hensen's node. In older embryos transcripts are detected in the endoderm of the pharyngeal pouches, the ectoderm of the second and third pharyngeal arches and the stomodeum. Expression was also detected in the segmental plate and in the posterior half of the three most-recently generated somites.

Amino Acid Sequence↗
PubMed1994

Competition between nuclear localization and secretory signals determines the subcellular fate of a single CUG-initiated form of FGF3.

The presumed open reading frame for mouse FGF3, starting at the most 5' AUG codon, predicts a hydrophobic N-terminus characteristic of a signal peptide for secretion. However, in reticulocyte lysates and transfected COS-1 cells, the full-length Fgf-3 cDNA is translated almost exclusively from an upstream CUG codon. The resultant products are distributed in both the nucleus and the secretory pathway, implying that the single CUG-initiated form of FGF3 has dual fates. By analysing a series of deletion and replacement mutants and by linking parts of FGF3 to a heterologous protein, we show that secretion is mediated by cleavage adjacent to the previously defined signal peptide, whereas nuclear localization is determined primarily by a classical but relatively weak bipartite motif. In the context of FGF3, nuclear localization also requires the N-terminal sequences which lie upstream of the signal peptide. Thus, the subcellular fate of FGF3 is determined by the competing effects of signals for secretion and nuclear localization within the same protein, rather than by alternative initiation or processing.

Amino Acid Sequence↗
PubMed1994

Amplification and overexpression of cyclin D1 in breast cancer detected by immunohistochemical staining.

Immunohistochemical staining with a monoclonal antibody against human cyclin D1 can be used to identify breast cancers that have an amplification of the q13 region of chromosome 11. In general, the intensity of staining is directly proportional to the degree of DNA amplification. In two unusual tumors, in which the CCND1 locus is highly amplified but staining is relatively weak, it appears that the DNA has undergone rearrangement and that the amplified/rearranged CCND1 allele may have reduced transcriptional activity. More significantly, the immunohistochemical technique identifies additional tumors in which the cyclin D1 gene is overexpressed with only marginal or undetectable increases in copy number, implying that other mechanisms can lead to deregulated expression. These results suggest that the frequency of overexpression is much higher than previously concluded from DNA-based analyses and that more than one-third of human breast cancers may contain excessive levels of cyclin D1. The technique we describe should facilitate the detection of this abnormality in a clinical setting and clarify its prognostic significance.

Alleles↗
PubMed1994

Infrainguinal endovascular in situ saphenous vein bypass: ongoing results.

PURPOSE: With 70 cm "cutter" valvulotomes for valvulotomy and an electronically steerable nitinol catheter to occlude venous tributaries with platinum coils, endovascular in situ saphenous vein (EISV) bypass can be safely performed from within the saphenous vein. To determine whether EISV bypass could reduce hospital length of stay (LOS) and perioperative morbidity without compromising patency, another 53 EISV bypasses for limb salvage were performed. METHODS: Tributary occlusion was accomplished with only fluoroscopic surveillance with a new, smaller, and more steerable silicone-tipped nitinol catheter. RESULTS: Two (3.7%) wound complications occurred. The mean hospital LOS after operation was 4.2 days (range 2 to 29 days). All tributaries initially embolized remained occluded, and three "missed" arteriovenous fistulas were identified during follow-up extending to 15 month (mean 8.4 months). Eighty-eight percent (49 of 54) of phase II bypasses remained patent, whereas life-table analysis of all bypasses (phase I and II) was 77% (69/99) at 24 months follow-up (mean 13.6 months). By comparison, 41 infrainguinal saphenous vein in situ bypasses with "classic" open techniques were performed concurrently. The mean postoperative LOS was 11.6 days (range 4 to 42 days), wound complications occurred in 24% (10) of patients, and two "missed" arteriovenous fistulas were identified during follow-up. Eighty-three percent (34 of 41) of bypasses remain patent at 24 months follow-up (mean 16.2 months). CONCLUSIONS: If EISV bypass long-term patency rates remain similar to classic in situ bypass patency results, the additional benefits of decreased hospital LOS, reduced wound-related complications, shortened recuperation, and therefore increased health care savings gives this endovascular technique strong consideration as the possible future operation for infrainguinal saphenous veins in situ bypass.

Aged↗
PubMed1994

FGF-7 (keratinocyte growth factor) expression during mouse development suggests roles in myogenesis, forebrain regionalisation and epithelial-mesenchymal interactions.

We have isolated cDNA and genomic clones for the murine FGF-7 gene and examined its expression throughout development. Transcripts were transiently detected in the developing myocardium, differentially regulated between the atrium and ventricle. The gene was also expressed in the myotomes of the somites, coincident with FGF-4 and FGF-5 transcripts, and was detected transiently in cleaved muscles. Regional expression was detected in the ventricular zone of the developing forebrain at 14.5 d.p.c. Later in development, FGF-7 RNA was detected in mesenchymal tissues suggesting a role in epithelial-mesenchymal interactions and in the dermis consistent with its proposed role as a keratinocyte mitogen. Our results suggest that FGF-7 is likely to have diverse roles during development.

Amino Acid Sequence↗
PubMed1994

Absence of cyclin D/cdk complexes in cells lacking functional retinoblastoma protein.

Cyclins D1, D2 and D3 are thought to function in the G1 phase of the cell division cycle by regulating the activity of cyclin-dependent protein kinases. All three D-type cyclins can be shown to associate with two specific kinases, cdk4 and cdk6, providing at least six possible combinations. To establish whether different cell types require different subsets of these complexes and whether they are altered in tumours where D-cyclin expression is perturbed, we surveyed a series of tumour cell lines and compared them where possible to non-tumorigenic counterparts. Although complexes involving cdk4 or cdk6 were readily observed in many of the cell lines, no complexes were detectable in human cells harbouring DNA tumour virus oncoproteins or in which the retinblastoma gene product (pRb) is mutated or missing. These data suggest that as well as being a potential substrate for D-cyclin-kinases, functional pRb contributes to the formation or stability of the complexes, at least in human cells.

Breast Neoplasms↗
PubMed1994

CDK6 (PLSTIRE) and CDK4 (PSK-J3) are a distinct subset of the cyclin-dependent kinases that associate with cyclin D1.

Deregulated expression of cyclin D1 is a feature of several neoplastic and proliferative disorders, but its normal role in the cell cycle remains unclear. Here we show that in a squamous carcinoma cell line with 11-fold amplification of the CCND1 gene, cyclin D1 associates specifically with p33cdk4 (PSK-J3) and p38cdk6 (PLSTIRE), two closely related members of the cyclin-dependent kinase (CDK) family. In these tumour cells, there is little evidence for an association between cyclin D1 and other CDKs, but in diploid human fibroblasts both CDK2 and CDK5 can be co-precipitated with cyclin D1, as well as CDK4. The data suggest that D-type cyclins participate in multiple interactions with CDKs but that the nature or stoichiometry of these associations may differ in different types of cell.

Amino Acid Sequence↗