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M Negrini

Publications and source records attributed to M Negrini.

At least 73 records · Page 4Linked to original sources
PubMed1995

Characterization of the mammalian YAP (Yes-associated protein) gene and its role in defining a novel protein module, the WW domain.

We report cDNA cloning and characterization of the human and mouse orthologs of the chicken YAP (Yes-associated protein) gene which encodes a novel protein that binds to the SH3 (Src homology 3) domain of the Yes proto-oncogene product. Sequence comparison between mouse, human, and chicken YAP proteins showed an inserted sequence in the mouse YAP that represented an imperfect repeat of an upstream sequence. Further analysis of this sequence revealed a putative protein module that is found in various structural, regulatory, and signaling molecules in yeast, nematode, and mammals including human dystrophin. Because one of the prominent features of this sequence motif is two tryptophans (W), we named it the WW domain (Bork, P., and Sudol, M. (1994) Trends Biochem. Sci. 19, 531-533). Since its delineation, more proteins have been shown to contain this domain, and we report here on the widespread distribution of the WW module and present a discussion of its possible function. We have also shown that the human YAP gene is well conserved among higher eukaryotes, but it may not be conserved in yeast. Its expression at the RNA level in adult human tissues is nearly ubiquitous, being relatively high in placenta, prostate, ovary, and testis, but is not detectable in peripheral blood leukocytes. Using fluorescence in situ hybridization on human metaphase chromosomes and by analyzing rodent-human hybrids by Southern blot hybridization and polymerase chain reaction amplification, we mapped the human YAP gene to chromosome band 11q13, a region to which the multiple endocrine neoplasia type 1 gene has been mapped.

Adaptor Proteins, Signal Transducing↗
PubMed1995

Involvement of the ALL-1 gene in a solid tumor.

Translocations involving chromosome band 11q23, found in 5-10% of human acute leukemias, disrupt the ALL-1 gene. This gene is fused by reciprocal translocation with a variety of other genes in acute lymphoblastic and myelogenous leukemias, and it undergoes self-fusion in acute myeloid leukemias with normal karyotype or trisomy 11. Here we report an alteration of the ALL-1 gene in a gastric carcinoma cell line (Mgc80-3). Characterization of this rearrangement revealed a three-way complex translocation, involving chromosomes 1 and 11, resulting in a partial duplication of the ALL-1 gene. Sequencing of reverse transcription-PCR products and Northern blot analysis showed that only the partially duplicated ALL-1 gene was transcribed, producing an mRNA with exon 8 fused to exon 2. This report of ALL-1 gene rearrangement in a solid tumor suggests that ALL-1 plays a role in the pathogenesis of some solid malignancies. The absence of the normal transcript in this cell line, in association with the loss-of-heterozygosity studies on chromosome 11q23 seen in solid tumors, suggests that ALL-1 is involved in tumorigenesis by a loss-of-function mechanism.

Animals↗
PubMed1995

Detection and cloning of a common region of loss of heterozygosity at chromosome 1p in breast cancer.

The short arm of chromosome 1 is frequently affected by rearrangements in a variety of human malignancies. Genetic alterations, predominantly deletions, which are indicative of the presence of a putative tumor suppressor gene at chromosome 1p, are observed in breast cancer. In order to define the altered locus, eleven highly polymorphic microsatellite markers on chromosome 1p were used to detect loss of heterozygosity. We analyzed 52 cases of breast cancer and found 4 common deleted regions at chromosome 1p. Twenty-two of 52 (42%) informative patients showed at least 1 affected locus. The region most frequently exhibiting loss of heterozygosity was 1p31 (11/39; 28%); the other three common deleted regions were 1p36 (10/44; 23%), 1p35-36 (5/40; 13%), and 1p13 (8/39; 21%). These data suggest that one or more putative tumor suppressor genes may reside on chromosome 1p. We have cloned the entire region of interest at 1p31 in yeast artificial chromosomes. This yeast artificial chromosome contig can be used for fine mapping of the region and cloning of the candidate tumor suppressor gene.

Base Sequence↗
PubMed1995

A BK virus episomal vector for constitutive high expression of exogenous cDNAs in human cells.

A BK virus (BKV) episomal vector (pRPneoCMV) was constructed for expression of cDNAs under control of the cytomegalovirus (CMV) immediate-early promoter. Transfection of pRPneoCMV for expression of the chloramphenicol acetyltransferase (CAT) gene in several human cell lines showed that the CMV promoter is more efficient than the HIV-1 and RSV LTRs in directing gene expression from episomal vectors. In 293 human cells pRPneoCMV/CAT is twenty times more active in CAT expression than the well known pSV2CAT vector in COS7 cells. Stable expression of the gene of the herpes simplex virus type 1 and type 2 glycoprotein G, cloned into pRPneoCMV, was obtained in 293 cells. This vector will allow direct cloning of newly synthesized cDNAs whose expression can be monitored in human cells.

BK Virus↗
PubMed1995

A novel t(9;11)(p22;q23) with ALL-1 gene rearrangement associated with progression of a myeloproliferative disorder to acute myeloid leukemia.

We have analyzed genomic DNAs from a patient who developed acute myeloid leukemia 1 year after a myeloproliferative disorder was diagnosed. The development of the acute leukemia was associated with the acquisition of a t(9;11)(p22;q23) chromosome translocation. ALL-1 gene rearrangement, on chromosome 11, was present at the onset of the acute phase, but not during the chronic phase of the myeloproliferative disorder. The genomic rearrangement on chromosome 9 was within an unidentified region. By the use of polymerase chain reaction, we were able to determine that the chromosomal rearrangement was completely absent during the chronic phase of the myeloproliferative disorder, indicating that the ALL-1 gene rearrangement was causally related to the development of the acute phase. The rapid progression into the acute phase suggests that this case might be therapy related. This work provides a clear example of association of a molecular defect with the development of a specific clinical leukemic stage, and supports the indication that ALL-1 gene rearrangement is associated with poor clinical outcome in adult leukemias.

Adult↗
PubMed1994

Loss of heterozygosity at 11q22-q23 in breast cancer.

Studies of loss of heterozygosity (LOH) in breast tumor DNA suggest that several tumor suppressor genes participate in the pathogenesis of breast cancer. Although the short arm of chromosome 11 has been implicated in breast cancer development, no previous LOH studies have indicated the involvement of a suppressor gene on 11q in breast carcinoma. To this end, tumor samples and corresponding normal tissue were collected from 62 unselected patients with primary breast cancer, and the extracted DNA was analyzed by polymerase chain reaction using microsatellite markers on chromosome 11. We found that 39% of the tumors (22 of 57 informative cases) revealed allelic loss in the region 11q22-23, and this loss was independent of LOH found to occur on 11p15. Interestingly, more than 90% of the tumors showed concordant loss of alleles at both 11q and 17p. The marker D11S528, showing LOH in 39% of informative cases, had the highest frequency of LOH among the markers that were used. The data presented indicate that the common overlapping region of LOH is between the loci D11S35 and D11S29, suggesting that this area contains a tumor suppressor gene frequently lost in breast cancer.

Ataxia Telangiectasia↗
PubMed1994

Multiple loci on human chromosome 11 control tumorigenicity of BK virus transformed cells.

BK virus (BKV) is a human papovavirus that readily transforms rodent cells, but not human cells, to a neoplastic phenotype, suggesting that tumor-suppressor functions expressed in human cells control BKV oncogenicity. Transfer of a normal human chromosome 11 to BKV-transformed mouse cells suppresses the malignant phenotype. In this report we map the regions of chromosome 11 involved in tumor suppression. Transfer of chromosome 11 to the BKV-transformed hamster cell line HKBK produces monochromosomic hybrids retaining only portions of the transferred human chromosome. We have compared the tumorigenicity of the hybrids with the molecular mapping of chromosome 11 retained regions. This analysis indicated that 3 regions of human chromosome 11, 11p15.5, 11p13 and 11q13, cooperate in tumor suppression. However, 11q13 seems the most important, since all the HKBK/H11-induced tumors analysed had lost this region, whereas 11p15.5 and 11p13 were sometimes retained. The chromosomal regions identified in this study are deleted in several types of human tumors, suggesting that the BKV transformation system specifically detects tumor-suppressor genes on chromosome 11 that are involved in human oncogenesis. This model may be of use in isolating and cloning such genes. The results of this report raise the possibility that BKV may have a synergistic tumorigenic effect in human cells where tumor-suppressor genes controlling its oncogenic potential are inactivated.

Animals↗
PubMed1994

Down-regulation of bcl-2 by p53 in breast cancer cells.

bcl-2 and p53 gene products have been both linked to programmed cell death pathways. We have analyzed several human breast cancer cell lines for the expression of bcl-2 and p53. We found an inverse correlation between the expression of the two proteins. The result suggested that mutant p53 could substitute for bcl-2 function in breast cancer cells and that could also down-regulate bcl-2 expression. We found, indeed, that overexpression of a mutant p53 (mut 175) in MCF-7 cells could induce down-regulation of bcl-2 both at protein and mRNA level. However, the promoter region of the human bcl-2 gene does not contain the negative regulatory element responsible for the down-regulation. If this mechanism will be proved also for the wild-type p53 allele, it may disclose a possible mechanism for p53-induced apoptosis: down-regulation of bcl-2.

Alleles↗
PubMed1994

Tumor and growth suppression of breast cancer cells by chromosome 17-associated functions.

Losses of functions from chromosome 17 are the most frequent genetic abnormalities in human breast cancer. To assess the biological role of chromosome 17 in the development of breast cancer, we transferred a normal human chromosome 17 to two breast cancer cell lines. No viable clone maintaining an intact chromosome was obtained in either MDA-MB-231 or MCF-7. Only one MDA-231/H17 clone contained the long arm of the transferred chromosome 17. Interestingly, this clone lost the ability to induce tumors in nude mice, indicating that at least one gene mapping to the long arm of chromosome 17 could suppress the tumorigenic phenotype. The p53 protein most likely was responsible for the selective loss of the short arm of the chromosome. Both cell lines have no wild-type p53 activity. MDA-MB-231 carries a single mutant TP53 allele, while MCF-7 carries two wild-type alleles, but p53 protein is excluded from the nucleus. Transfection in both cell lines of vectors expressing wild-type p53 produced only clones with rearrangements of the transfected TP53 complementary DNA. Thus, nonregulated expression of the p53 protein driven by the strong cytomegalovirus promoter may have triggered a rapid process of cell death. Stable expression of a mutant p53 in MCF-7 cells proved that nuclear localization of the protein was possible; however, no progression toward an estrogen-independent tumorigenic phenotype was induced. This work indicates that functional inactivation of the wild-type p53 protein and of the product of a gene located on 17q are essential to the development of breast neoplasms.

Amino Acid Sequence↗
PubMed1994

Suppression of tumorigenicity of breast cancer cells by microcell-mediated chromosome transfer: studies on chromosomes 6 and 11.

Development of breast cancer has been associated with deletions at multiple chromosomal regions, including 6q, 11p, and 11q. In this study we analyzed the effects of the introduction of chromosomes 6 and 11 on the cell phenotype of the breast cancer cell lines MDA-MB-231 and MCF-7. Chromosome 6 induced alterations of in vitro growth properties and suppressed tumorigenicity of MDA-MB-231 cells. Spontaneous reduction of the transferred chromosome allowed mapping of the tumor suppressor gene(s) to region 6q21-q23 and/or 6q26-q27. Clones MCF-7/H6 underwent a senescence process that lasted five months. Chromosome 11 had no effect on MDA-MB-231 cells, although it suppressed tumorigenicity of MCF-7 cells. A MCF-7/H11 clone lacking the short arm of the transferred chromosome retained tumorigenicity, however, tumor cell growth was significantly reduced. These results suggest that each chromosomal arm may contain genes important for the suppression of MCF-7 tumorigenic properties.

Breast Neoplasms↗
PubMed1994

Minor myeloid component in Ph chromosome-positive acute lymphoblastic leukaemia: correlation with cytogenetic pattern and implication for poor response to therapy.

Morphological, immunological and cytogenetic features were studied in 27 adults presenting with Ph chromosome-positive acute lymphoblastic leukaemia (ALL), in correlation with clinical outcome. Twenty patients (group 1) were diagnosed as having typical ALL according to the FAB criteria supported by immunological findings. Less than 1% blast cells with azurophilic granules were detected in all cases. Myeloid cytochemistry, i.e. peroxidase and Sudan black-B stain, was negative in all cases. A minor phenotype deviation consisting of the expression of the CD13 myeloid-associated marker was detected in two patients. In seven patients (group 2) a diagnosis of ALL with a minor myeloid component was made because of the presence of a majority of lymphoid blasts and of 5-15% blast cells with morphological cytochemical and immunological features of the myeloid lineage. Abnormal metaphases were found in 6/20 (30%) patients in group 1, compared with 7/7 (100%) patients in group 2. All patients were treated by antilymphoid regimens; however, complete remission was achieved in 17/20 (85%) patients in group 1 versus 1/7 (14.3%) patients in group 2. Median survival was 16 months, range < 1-120+ in group 1 and 9 months, range < 1-15 in group 2. It is concluded that morphological, immunological and cytogenetic studies allow for the recognition of two cytological subsets of Ph+ ALL. The presence of a minor myeloid component in otherwise typical Ph chromosome-positive ALL may be associated with a distinct cytogenetic pattern and poor responses to antilymphoid therapy.

Adult↗
PubMed1994

[The evolution of hospital mortality due to acute myocardial infarct in the first 2 GISSI studies. Participants in the GISSI 1 and GISSI 2 studies. Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto Miocardico].

During the short while of 5 years, between 1984 and 1985, two large clinical trials have been performed in Italy concerning fibrinolytic therapy in Acute Myocardial Infarction: GISSI 1 and GISSI 2. They made possible to evaluate the evolution of demographic and clinical features, the in-hospital mortality rate, and the causes of death of a huge number of patients admitted to CCU throughout the whole country. Out of 31,826 patients with acute myocardial infarction admitted to 176 CCU participating to the GISSI 1 16.9% were 75 years old and 24.7% were females; 21.8% and 26.4% were the percentages in the 38,086 patients admitted to the 223 CCU participating in the GISSI 2. Despite the higher prevalence of the two demographic characteristic with the worse prognosis, the in-hospital mortality rates were respectively 12.2% in the GISSI 1 and 10.0% in the GISSI 2 studies, with a statistically significant decrease (RR 0.84; C.L. 0.80-0.88). The significant decrease in the in-hospital mortality concerns also the patients populations selected according to the same criteria of inclusion in the two trials (within 6 hours from the onset of symptoms and with only ST elevation at the ECG of admission) and to the treatment with fibrinolytic drug (SK or rtPA). As a matter of fact 468 patients died of the 4,696 (10.0%) treated with SK in the GISSI 1 against 1,092 patients of 12,381 (8.8%) enrolled in the GISSI 2 and treated with SK or rtPA (RR 0.87; L.C. 0.78-0.98). The reduction of in-hospital mortality may be explained by some differences in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Distribution↗
PubMed1993

Systemic expression of HIV-1 tat gene in transgenic mice induces endothelial proliferation and tumors of different histotypes.

The human immunodeficiency virus tat protein, a transactivator of viral and cellular genes, is suspected to be involved in the pathogenesis of acquired immunodeficiency syndrome-associated tumors. We report that transgenic mice carrying a recombinant DNA containing BK virus early region and the human immunodeficiency virus tat gene develop skin leiomyosarcomas, squamous cell papillomas and carcinomas, adenocarcinomas of skin adnexa, glands, and B-cell lymphomas. Although the incidence of hepatocellular carcinoma is low, most animals show a liver cell dysplasia of variable degree. These mice are also affected by skin lesions resembling the early stages of Kaposi's sarcoma. The transgene was detected intact in all the organs of transgenic mice, generally as multiple tandemly integrated copies. BK virus early region and tat were expressed in essentially all tissues and organs of BK virus/tat transgenic mice. This transgenic mouse model is representative of the systemic involvement of tat in human immunodeficiency virus natural infection and may be applied to investigate the role of tat in malignancies associated to acquired immunodeficiency syndrome, to study Kaposi's sarcoma pathogenesis and cell of origin, to characterize preneoplastic conditions established by tat in the skin and liver, and to assess in vivo the efficacy of antiangiogenic and anti-tat-specific drugs.

Adenocarcinoma↗
PubMed1993

Potential topoisomerase II DNA-binding sites at the breakpoints of a t(9;11) chromosome translocation in acute myeloid leukemia.

We have examined a t(9;11)(p22;q23) chromosome translocation in an acute myeloid leukemia of an infant. The breakpoints on the two chromosomes occurred within introns of the involved genes: AF-9 on chromosome 9, and ALL-1 on chromosome 11. Sequence analysis identified heptamers flanking the breakpoints on both chromosomes 9 and 11, suggesting that the V-D-J recombinase was involved in the translocation. The presence of an N-region between the two chromosomes supports the hypothesis that a mistake in V-D-J joining was involved in the genesis of the translocation and indicates that terminal deoxynucleotidyl transferase was expressed in the cells from which this acute myeloid leukemia originated. In addition, potential topoisomerase II DNA-binding sites were found near the breakpoints of both chromosomes, suggesting the involvement of altered topoisomerase II activity in this translocation. Altered topoisomerase II activity in the presence of an active V-D-J recombinase may be a pathogenetic mechanism of acute myeloid leukemia with rearrangements at 11q23.

Amino Acid Sequence↗
PubMed1993

Common region of ALL-1 gene disrupted in epipodophyllotoxin-related secondary acute myeloid leukemia.

Translocations at chromosomal band 11q23 characterize most de novo acute lymphoblastic leukemias (ALL) of infants, acute myeloid leukemias (AML) of infants and young children, and secondary AMLs following epipodophyllotoxin exposure. The chromosomal breakpoints at 11q23 have been cloned from isolated cases of de novo ALL and AML. Using an 859-base pair BamHI fragment of human ALL-1 complementary DNA that recognizes the genomic breakpoint region for de novo ALL and AML, we investigated two cases of secondary AML that followed etoposide-treated primary B-lineage ALL. In the first case, the translocation occurred between chromosomes 9 and 11 and the breakpoint at 11q23 localized to the same 9-kilobase region of the ALL-1 gene that is disrupted in most of the de novo leukemias. In the second case the translocation was between chromosomes 11 and 19. The breakpoint occurred outside of the ALL-1 breakpoint cluster region.

Child, Preschool↗
PubMed1993

Thrombolytic therapy in selected patients with impending myocardial reinfarction.

BACKGROUND: In selected patients with postinfarction angina and impending reinfarction, thrombolysis with recombinant tissue-type plasminogen activator (rt-PA) or streptokinase is highly effective in avoiding a new myocardial infarction. METHODS: To avoid major cardiac events, we treated 14 consecutive patients with thrombolytic therapy because of impending reinfarction with ECG ST-segment elevation. Thirteen patients received rt-PA (100 mg over 3 hours), and one patient received streptokinase (1.5 million IU over 1 hour). All patients had failed to respond to maximal medical therapy with intravenous nitrates, beta-blockers, Ca-antagonists, heparin, and opiates. RESULTS: In all patients, clinical and ECG signs of acute ischemia resolved completely within 1 hour after beginning thrombolysis, and no patient developed biochemical markers of myocardial infarction. Ten patients underwent coronary angiography: five had three-vessel disease, two had two-vessel disease, and three had one-vessel disease. The culprit lesion was located in the left anterior descending artery in eight cases and the right coronary artery in two. No patient showed intracoronary thrombus. Four patients underwent successful, semiurgent percutaneous transluminal coronary angioplasty; three received an elective and two an urgent coronary artery bypass graft. CONCLUSIONS: Thrombolysis (or repeated thrombolysis) is effective in selected patients with clinical ECG signs of impending reinfarction. It can temporarily stabilize the condition of many patients, thus allowing safer mechanical revascularization to be performed.

Aged↗