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R Montesano

Publications and source records attributed to R Montesano.

At least 37 records · Page 2Linked to original sources
PubMed2000

Abnormal expression of the ATM and TP53 genes in sporadic breast carcinomas.

The ataxia telangiectasia gene (ATM) has been implicated as a risk factor in the development of sporadic breast carcinomas. ATM protein expression was analyzed by immunohistochemistry in 17 breast carcinomas with two monoclonal antibodies whose immunohistochemical use was first validated by comparing the immunoreactivity observed in spleen samples from ataxia telangiectasia and trauma patients. In normal breast ducts, ATM showed nuclear expression in the epithelial but not in the myoepithelial cells. In contrast, this nuclear expression was absent or low in the epithelial cancer cells in 10 of 17 (59%) of the tumors studied. Allelic imbalance in the ATM gene was found in three of seven tumors examined. Two of these showed reduced ATM protein expression, but this did not correlate with the presence of ATM mutations in the tumor DNA detected by restriction endonuclease fingerprinting screening. These results suggest that the reduced ATM protein expression could be attributable, in certain tumors, to deletions or rearrangements within or close to the ATM gene. Positive p53 immunostaining was found in 10 tumors, with TP53 mutations detected in 8. Three tumors had both low ATM expression and mutated TP53. Our results indicate that in the majority (15 of 17) of the sporadic breast carcinomas examined, not only is the functionality of the ATM-p53-mediated DNA damage response compromised, but also other signaling pathways activated by these two multifunctional proteins are likely to be impaired, which could be a contributing factor to tumor development and progression.

Allelic Imbalance↗
PubMed1999

Genetic dissection of dome formation in a mammary cell line: identification of two genes with opposing action.

In this work, we extend the study of the genes controlling the formation of domes in the rat mammary cell line LA7 under the influence of DMSO. The role of the rat8 gene has already been demonstrated. We have now studied two additional genes. The first, called 133, is the rat ortholog of the human epithelial membrane protein 3 (EMP3), a member of the peripheral myelin protein 22 (PMP22)/EMP/lens-specific membrane protein 20 (MP20) gene family that encodes for tetratransmembrane proteins; it is expressed in the LA7 line in the absence of DMSO but not in its presence. The second gene is the beta subunit of the amiloride-sensitive Na(+) channel. Studies with antisense oligonucleotides show that the formation of domes is under the control of all three genes: the expression of rat8 is required for both their formation and their persistence; the expression of the Na(+) channel beta subunit is required for their formation; and the expression of gene 133 blocks the expression of the Na(+) channel genes, thus preventing formation of the domes. The formation of these structures is also accompanied by the expression of alpha(6)beta(1) integrin, followed by that of E-cadherin and cytokeratin 8. It appears, therefore, that dome formation requires the activity of the Na(+) channel and the rat8-encoded protein and is under the negative control of gene 133. DMSO induces dome formation by blocking this control.

Animals↗
PubMed1999

Laminin and beta1 integrins are crucial for normal mammary gland development in the mouse.

We have examined the role of integrin-extracellular matrix interactions in the morphogenesis of ductal structures in vivo using the developing mouse mammary gland as a model. At puberty, ductal growth from terminal end buds results in an arborescent network that eventually fills the gland, whereupon the buds shrink in size and become mitotically inactive. End buds are surrounded by a basement membrane, which we show contains laminin-1 and collagen IV. To address the role of cell-matrix interactions in gland development, pellets containing function-perturbing anti-beta1 integrin, anti-alpha6 integrin, and anti-laminin antibodies respectively were implanted into mammary glands at puberty. Blocking beta1 integrins dramatically reduced both the number of end buds per gland and the extent of the mammary ductal network, compared with controls. These effects were specific to the end buds since the rest of the gland architecture remained intact. Reduced development was still apparent after 6 days, but end buds subsequently reappeared, indicating that the inhibition of beta1 integrins was reversible. Similar results were obtained with anti-laminin antibodies. In contrast, no effect on morphogenesis in vivo was seen with anti-alpha6 integrin antibody, suggesting that alpha6 is not the important partner for beta1 in this system. The studies with beta1 integrin were confirmed in a culture model of ductal morphogenesis, where we show that hepatocyte growth factor (HGF)-induced tubulogenesis is dependent on functional beta1 integrins. Thus integrins and HGF cooperate to regulate ductal morphogenesis. We propose that both laminin and beta1 integrins are required to permit cellular traction through the stromal matrix and are therefore essential for maintaining end bud structure and function in normal pubertal mammary gland development.

Animals↗
PubMed1999

Hepatitis B vaccination in infancy in The Gambia: protection against carriage at 9 years of age.

To estimate the efficacy in The Gambia (West Africa) of infant hepatitis B vaccination against infection and carriage with the virus at the age of 9 years. The HBV status of 9-year old children vaccinated in infancy was compared to that of unvaccinated children of the same age. Eight percent of the vaccinated children had been infected by HBV compared to 50% of the unvaccinated control group; HBV carrier status was 0.6 and 10% respectively, resulting in a vaccine efficacy of 83% against infection and of 95% against chronic carriage. The results show that infant vaccination provides a high level of protection at the age of nine years against both HBV infection and chronic carrier status and no booster dose of vaccine is required in the first decade. These findings support the WHO recommendation for the introduction of HBV vaccination into the Expanded Programme on Immunization in Africa.

Carrier State↗
PubMed1999

Chromogranin A alters ductal morphogenesis and increases deposition of basement membrane components by mammary epithelial cells in vitro.

The extracellular function of chromogranin A (CgA), a glycoprotein widely distributed in secretory vesicles of neurons and neuroendocrine cells, has not been clearly established. To examine whether CgA might modulate the biological properties of epithelial cells, we used an in vitro model of ductal morphogenesis in which mammary epithelial (TAC-2) cells are grown in three-dimensional collagen gels. Whereas under control conditions TAC-2 cells formed thin, branched cords with pointed ends, in the presence of CgA they formed thicker cords with bulbous extremities, reminiscent of growing mammary ducts in vivo. Immunofluorescence analysis demonstrated that CgA increases the deposition of three major basement membrane components, i.e., collagen type IV, laminin, and perlecan, around the surface of the duct-like structures. Similar effects were observed with CgA partially digested with endoproteinase Lys-C, suggesting that one or more fragments of CgA are endowed with the same activity. These findings reveal a hitherto unsuspected activity for CgA, i.e., the ability to alter ductal morphogenesis and to promote basement membrane deposition in mammary epithelial cells.

Basement Membrane↗
PubMed1999

New role for tRNA and its fragment purified from human urinary bladder carcinoma conditioned medium: inhibition of endothelial cell growth.

The growth of endothelial cells is necessary for angiogenesis, which in turn is required for later steps of tumor progression. In an attempt to purify new modulators of endothelial cell growth from the conditioned medium of human urinary bladder carcinoma cells, we isolated a small and stable oligonucleotide containing 10 to 16 bases. This oligonucleotide inhibited the growth of endothelial cells in vitro and was identified as a fragment of transfer RNA (tRNA). When unfractionated bovine tRNA was added to the cell culture, it specifically inhibited growth of endothelial cells, but not smooth muscle cells, bovine kidney cells, 3T3 fibroblasts, and several cancer cell lines. In contrast, ribosomal RNA, total yeast RNA, and single nucleosides from tRNA hydrolysate had no effect. These results demonstrate a new role for tRNA and its fragment as a selective endothelial cell inhibitor in vitro.

3T3 Cells↗
PubMed1999

IARC p53 mutation database: a relational database to compile and analyze p53 mutations in human tumors and cell lines. International Agency for Research on Cancer.

The tumor suppressor p53 gene is the most frequently mutated gene in human cancer. To date, more than 10,000 mutations have been described in the literature, and these data are available in various electronic formats on the World Wide Web. Here we describe the structure and format of the different p53 datasets maintained and curated at the International Agency for Research on Cancer (IARC) in Lyon, France. These include p53 somatic mutations (more than 10,000 entries), p53 germline mutations (144 entries), and p53 polymorphisms (13 entries), with the somatic mutations organized into a relational database using AccessTM. The main features of these datasets are (1) controlled entry with standardized format and restricted vocabulary, (2) inclusion of annotations on individual characteristics and exposures, and (3) a classification of pathologies based on the International Classification of Diseases for Oncology (ICD-O). In addition, several interfaces have been developed to analyze the data in order to produce mutation spectra, codon analyses, or visualization of the mutation with the tertiary structure of the protein. All datasets and tools for analysis are available at http://www.iarc.fr/p53/homepage.

Databases, Factual↗
PubMed1999

Sources of bias in the detection and reporting of p53 mutations in human cancer: analysis of the IARC p53 mutation database.

p53 gene encodes a transcription factor with tumor suppressive properties and to date, somatic mutation of this gene is the most common genetic event in human cancer. A relational database has been developed to facilitate the retrieval and analysis of these mutations at the International Agency for Research on Cancer (IARC) and it currently contains information on over 8000 individual tumors and cell lines. Many factors may influence the detection and reporting of mutations, including selection of tumor samples, study design, choice of methods, and quality control. There is also concern that several biases may affect the way data appear in the literature. Minimizing these biases is an essential methodological issue in the development of mutation data-bases. In this paper, we review and discuss these main sources of bias and make recommendations to authors in order to minimize bias in mutation detection and reporting.

Bias↗
PubMed1999

International Agency for Research on Cancer fellowships programme-over 30 years of experience.

In 1966 the International Agency for Research on Cancer (IARC) initiated a fellowship programme designed for young postdoctoral scientists from any country in the world who wish to receive training in another country in an area relevant to the aetiology and pathogenesis of cancer. Various disciplines are covered such as cellular and molecular biology, pathology, genetics and biochemistry, and particular attention is given to training in cancer epidemiology. A total of 471 fellowships have been awarded during the last 32 years, averaging 15 fellowships per year, and representing approximately one in four of the applications evaluated every year. Thirty-six percent of the total number of fellowships awarded have come from developing countries and eastern Europe. North America and western Europe are the regions preferentially selected by 98% of the fellows for training, with the USA (48%) and the UK (19%) remaining the most frequently selected countries for a host laboratory. Approximately 82-85% of fellows returned to their home countries and around 82% remain active in cancer research. A total of 101 fellowships have been awarded in epidemiology or biostatistics with the majority of IARC fellows in epidemiology originating from developing countries or developed countries in which the teaching of chronic diseases epidemiology is deficient. In addition, the IARC has received considerable input into its activities through its fellowship programme. The IARC fellowship programme is an effective tool in the provision of training in cancer research to young scientists worldwide, selected on the basis of scientific excellence and has made a substantial contribution to the development of cancer research in many countries.

Humans↗
PubMed1999

Characterization of cytochrome P450 expression in human oesophageal mucosa.

The expression of cytochrome (CYP) P450 enzymes in human oesophageal mucosa was investigated in a total of 25 histologically non-neoplastic surgical tissue specimens by using specific antibodies in immunoblots and by RT-PCR mRNA analysis. The presence of CYP1A, 2E1, 3A and 4A enzymes was demonstrated by both techniques; CYP2A reactive protein was also detected by immunoblot. The presence of CYP4B1 mRNA was established but no specific antibody was available for detection of the corresponding protein by immunoblot. CYP2B6/7 mRNA was not detected in any sample. The mRNA transcripts for CYP1A1, 2E1, 4A11 and 4B1 were consistently detected in the majority of samples (>84%), whereas CYP1A2 mRNA was only detected in 11 of 19 specimens examined. An RT-PCR method to differentiate CYP3A4 and 3A5 mRNA was developed. This demonstrated CYP3A5 mRNA expression in all samples tested, whereas CYP3A4 mRNA was not detectable, suggesting that CYP3A5 is the major CYP3A protein in human oesophagus. There were significant interindividual variations in the amount of proteins, ranging from 8-fold for CYP4A to 43-fold for CYP2E1. For each patient, data on exposure to risk factors for oesophageal cancer were available, including tobacco smoke, alcohol, gastro-oesophageal reflux and hot beverage consumption. None of these risk factors or other patient characteristics (age, sex, tumour location and tumour stage) were correlated with the protein level of the individual CYP enzymes as determined by quantitation of immunoblot staining. However, the small series of samples precludes any strong conclusion concerning the lack of such correlations. There were no differences between squamous cell carcinomas and adenocarcinomas in either the qualitative or quantitative expression of the CYP enzymes. These data demonstrate that a range of CYP enzymes are expressed in human oesophageal mucosa and indicate that this tissue has the capacity to activate chemical carcinogens to reactive DNA binding metabolites.

Adult↗
PubMed1999

Constitutively active mitogen-activated protein kinase kinase MEK1 disrupts morphogenesis and induces an invasive phenotype in Madin-Darby canine kidney epithelial cells.

During certain developmental processes, as well as during tumor progression, polarized epithelial cells integrated within multicellular structures convert into scattered, freely migrating fibroblast-like cells. Despite the biological and clinical importance of this phenomenon, the intracellular biochemical cascades that control the switch between the epithelial and mesenchymal phenotypes have not been elucidated. Using Madin-Darby canine kidney (MDCK) cells (clone C7) as a model system, we have assessed the potential role of the mitogen-activated protein kinase (MAPK)/ extracellular signal-regulated kinase (ERK) cascade in the modulation of epithelial plasticity. When grown in three-dimensional collagen gels, MDCK-C7 cells form spherical cysts composed of polarized epithelial cells circumscribing a central lumen. This morphogenetic behavior is profoundly subverted in MDCK-C7 cells expressing a constitutively active MAPK/ERK kinase 1 (caMEK1) mutant (C7-caMEK1 cells). When suspended in collagen gels, C7-caMEK1 cells assume an elongated fibroblastoid shape and are unable to generate multicellular cysts. In addition, when seeded onto the surface of a collagen gel, C7-caMEK1 cells penetrate extensively into the underlying matrix, unlike wild-type and mock-transfected MDCK-C7 cells, which remain confined to the surface of the gel. Similar changes in morphogenetic and invasive properties are observed in MDCK-C7F cells, a nontransfected, stably dedifferentiated derivative of MDCK-C7 cells that expresses substantially increased ERK2 activity. Both C7-caMEK1 and MDCK-C7F cells but not wild-type or mock-transfected MDCK-C7 cells express activated M(r) 72,000 gelatinase A [matrix metalloproteinase (MMP)-2] as well as elevated levels of membrane type-1 MMP. Synthetic MMP inhibitors as well as recombinant tissue inhibitor of metalloproteinases 2 and 3 suppress the invasion of collagen gels and restore the capacity of C7-caMEK1 cells to form cysts, thereby implicating the membrane type-1 MMP/MMP-2 proteolytic system in epithelial cell invasiveness and loss of multicellular organization. Taken together, our data demonstrate that increased activity of the MEK1-ERK2 signaling module in MDCK-C7 cells is associated with failure of morphogenesis and expression of a highly invasive phenotype. Sustained activation of the MAPK cascade therefore results in the destabilization of the three-dimensional architecture and the conversion of polarized epithelial cells into migrating mesenchymal-like cells.

Animals↗
PubMed1998

In vitro repression of Brca1-associated RING domain gene, Bard1, induces phenotypic changes in mammary epithelial cells.

BRCA1-associated RING domain (BARD1) was identified as a protein interacting with the breast cancer gene product BRCA1. The identification of tumorigenic missense mutations within BRCA1 that impair the formation of BARD1-BRCA1 complexes, and of BARD1 mutations in breast carcinomas, sustain the view that BARD1 is involved in BRCA1-mediated tumor suppression. We have cloned the murine Bard1 gene and determined that its expression in different tissues correlates with the expression profile of Brca1. To investigate the function of Bard1, we have reduced Bard1 gene expression in TAC-2 cells, a murine mammary epithelial cell line that retains morphogenetic properties characteristic of normal breast epithelium. Partial repression of Bard1, achieved by the transfection of TAC-2 cells with plasmids constitutively expressing ribozymes or antisense RNAs, resulted in marked phenotypic changes, consisting of altered cell shape, increased cell size, high frequency of multinucleated cells, and aberrant cell cycle progression. Furthermore, Bard1-repressed cell clones overcame contact inhibition of cell proliferation when grown in monolayer cultures and lost the capacity to form luminal structures in three-dimensional collagen gels. These results demonstrate that Bard1 repression induces complex changes in mammary epithelial cell properties which are suggestive of a premalignant phenotype.

Animals↗
PubMed1998

Induction of tissue inhibitor of metalloproteinases-3 is a delayed early cellular response to hepatocyte growth factor.

Hepatocyte growth factor (HGF) stimulates mitogenic, motogenic, and morphogenic responses in various cell types. We analysed HGF-responsive cells by differential display PCR to identify HGF-induced genes that mediate these biological events. One of the genes identified encoded a member of the tissue inhibitor of metalloproteinases (TIMP) family, TIMP-3. HGF transiently induced TIMP-3 mRNA in keratinocytes as well as kidney and mammary epithelial cells maximally between 4 and 6 h post-stimulation. Increased TIMP-3 protein secretion returned to basal levels within 18 h, while the expression of gelatinases A and B remained unchanged, suggesting that temporary suppression of matrix degradation is a delayed early response to HGF. Ectopic overexpression of TIMP-3 in cultured leiomyosarcoma cells conferred an epithelial morphology, reduced cell growth rate, anchorage-independent growth, and matrix invasion in vitro. Antisense suppression of TIMP-3 was associated with a scattered, fibroblastic cell morphology, as well as enhanced proliferation, anchorage-independent growth, and matrix invasion. A survey of tumor cell lines revealed an inverse relationship between metastatic potential and TIMP-3 expression level. These data suggest that early, transient TIMP-3 expression mediates specific HGF-induced phenotypic changes, and that loss of TIMP-3 expression may enhance the invasion potential of certain tumors.

3T3 Cells↗
PubMed1998

Notch4 and Wnt-1 proteins function to regulate branching morphogenesis of mammary epithelial cells in an opposing fashion.

Elongation and branching of epithelial ducts is a crucial event during the development of the mammary gland. Branching morphogenesis of the mouse mammary epithelial TAC-2 cell line was used as an assay to examine the role of Wnt, HGF, TGF-beta, and the Notch receptors in branching morphogenesis. Wnt-1 was found to induce the elongation and branching of epithelial tubules, like HGF and TGF-beta 2, and to strongly cooperate with either HGF or TGF-beta 2 in this activity. Wnt-1 displayed morphogenetic activity in TAC-2 cells as it induced branching even under conditions that normally promote cyst formation. The Notch4(int-3) mammary oncoprotein, an activated form of the Notch4 receptor, inhibited the branching morphogenesis normally induced by HGF and TGF-beta 2. The minimal domain within the Notch4(int-3) protein required to inhibit morphogenesis consists of the CBF-1 interaction domain and the cdc10 repeat domain. Coexpression of Wnt-1 and Notch4(int-3) demonstrates that Wnt-1 can overcome the Notch-mediated inhibition of branching morphogenesis. These data suggest that Wnt and Notch signaling may play opposite roles in mammary gland development, a finding consistent with the convergence of the wingless and Notch signaling pathways found in Drosophila.

Amino Acid Sequence↗
PubMed1998

Cell adhesion and the integrin-linked kinase regulate the LEF-1 and beta-catenin signaling pathways.

The integrin-linked kinase (ILK) is an ankyrin repeat containing serine-threonine protein kinase that can interact directly with the cytoplasmic domains of the beta1 and beta3 integrin subunits and whose kinase activity is modulated by cell-extracellular matrix interactions. Overexpression of constitutively active ILK results in loss of cell-cell adhesion, anchorage-independent growth, and tumorigenicity in nude mice. We now show that modest overexpression of ILK in intestinal epithelial cells as well as in mammary epithelial cells results in an invasive phenotype concomitant with a down-regulation of E-cadherin expression, translocation of beta-catenin to the nucleus, formation of a complex between beta-catenin and the high mobility group transcription factor, LEF-1, and transcriptional activation by this LEF-1/beta-catenin complex. We also find that LEF-1 protein expression is rapidly modulated by cell detachment from the extracellular matrix, and that LEF-1 protein levels are constitutively up-regulated at ILK overexpression. These effects are specific for ILK, because transformation by activated H-ras or v-src oncogenes do not result in the activation of LEF-1/beta-catenin. The results demonstrate that the oncogenic properties of ILK involve activation of the LEF-1/beta-catenin signaling pathway, and also suggest ILK-mediated cross-talk between cell-matrix interactions and cell-cell adhesion as well as components of the Wnt signaling pathway.

Animals↗
PubMed1998

IARC Database of p53 gene mutations in human tumors and cell lines: updated compilation, revised formats and new visualisation tools.

Since 1989, about 570 different p53 mutations have been identified in more than 8000 human cancers. A database of these mutations was initiated by M. Hollstein and C. C. Harris in 1990. This database originally consisted of a list of somatic point mutations in the p 53 gene of human tumors and cell lines, compiled from the published literature and made available in a standard electronic form. The database is maintained at the International Agency for Research on Cancer (IARC) and updated versions are released twice a year (January and July). The current version (July 1997) contains records on 6800 published mutations and will surpass the 8000 mark in the January 1998 release. The database now contains information on somatic and germline mutations in a new format to facilitate data retrieval. In addition, new tools are constructed to improve data analysis, such as a Mutation Viewer Java applet developed at the European Bioinformatics Institute (EBI) to visualise the location and impact of mutations on p53 protein structure. The database is available in different electronic formats at IARC (http://www.iarc. fr/p53/homepage.htm ) or from the EBI server (http://www.ebi.ac.uk ). The IARC p53 website also provides reports on database analysis and links with other p53 sites as well as with related databases. In this report, we describe the criteria for inclusion of data, the revised format and the new visualisation tools. We also briefly discuss the relevance of p 53 mutations to clinical and biological questions.

Computer Communication Networks↗