PubMed Health⌕ Search

Biomedical subjects

J R Testa

Publications and source records attributed to J R Testa.

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

Human mesothelial cells are unusually susceptible to simian virus 40-mediated transformation and asbestos cocarcinogenicity.

Mesothelioma, a malignancy associated with asbestos, has been recently linked to simian virus 40 (SV40). We found that infection of human mesothelial cells by SV40 is very different from the semipermissive infection thought to be characteristic of human cells. Mesothelial cells are uniformly infected but not lysed by SV40, a mechanism related to p53, and undergo cell transformation at an extremely high rate. Exposure of mesothelial cells to asbestos complemented SV40 mutants in transformation. Our data provide a mechanistic explanation for the ability of SV40 to transform mesothelial cells preferentially and indicate that asbestos and SV40 may be cocarcinogens.

Asbestos↗
PubMed2000

Expression of GPC3, an X-linked recessive overgrowth gene, is silenced in malignant mesothelioma.

Gene expression changes in rat asbestos-induced malignant mesothelioma (MM) cells were investigated by differential mRNA display. A mRNA transcript identified by this approach was abundant in normal rat mesothelial cells but not expressed in rat MM cell lines. Northern blot analysis confirmed that this transcript is uniformly silenced in rat MM cell lines and primary tumors. Nucleotide sequence analysis revealed that this transcript is encoded by the rat glypican 3 gene (GPC3), whose human homolog is mutated in the Simpson-Golabi-Behmel overgrowth syndrome. Allelic loss at the GPC3 locus was infrequent (6.9%) in MM cell lines, and no mutations were found. GPC3 transcript levels were markedly decreased in 16 of 18 primary tumors and 17 of 22 human MM cell lines. Most of the cell lines were shown to have aberrant methylation of the GPC3 promoter region. In two of four human MM cell lines tested, GPC3 expression was restored after 2-deoxy 5-azacytidine (DAC)-mediated demethylation of its promoter region. Ectopic expression of GPC3 inhibited in vitro colony formation of human MM cells. Collectively, these data suggest that down-regulation of GPC3 is a common occurrence in MM and that GPC3, an X-linked recessive overgrowth gene, may encode a negative regulator of mesothelial cell growth.

Alleles↗
PubMed2000

The Fn14 immediate-early response gene is induced during liver regeneration and highly expressed in both human and murine hepatocellular carcinomas.

Polypeptide growth factors stimulate mammalian cell proliferation by binding to specific cell surface receptors. This interaction triggers numerous biochemical responses including the activation of protein phosphorylation cascades and the enhanced expression of specific genes. We have identified several fibroblast growth factor (FGF)-inducible genes in murine NIH 3T3 cells and recently reported that one of them, the FGF-inducible 14 (Fn14) immediate-early response gene, is predicted to encode a novel, cell surface-localized type Ia transmembrane protein. Here, we report that the human Fn14 homolog is located on chromosome 16p13.3 and encodes a 129-amino acid protein with approximately 82% sequence identity to the murine protein. The human Fn14 gene, like the murine Fn14 gene, is expressed at elevated levels after FGF, calf serum or phorbol ester treatment of fibroblasts in vitro and is expressed at relatively high levels in heart and kidney in vivo. We also report that the human Fn14 gene is expressed at relatively low levels in normal liver tissue but at high levels in liver cancer cell lines and in hepatocellular carcinoma specimens. Furthermore, the murine Fn14 gene is rapidly induced during liver regeneration in vivo and is expressed at high levels in the hepatocellular carcinoma nodules that develop in the c-myc/transforming growth factor-alpha-driven and the hepatitis B virus X protein-driven transgenic mouse models of hepatocarcinogenesis. These results indicate that Fn14 may play a role in hepatocyte growth control and liver neoplasia.

3T3 Cells↗
PubMed2000

Mapping of AKT3, encoding a member of the Akt/protein kinase B family, to human and rodent chromosomes by fluorescence in situ hybridization.

Previously, a rodent cDNA encoding the third member of the Akt/PKB family of serine/threonine kinases was cloned. We have now cloned the human homolog of this cDNA, and we have used this clone to map the AKT3 gene to human chromosome 1q44 by fluorescence in situ hybridization (FISH). We have also mapped the rodent homologs of AKT3 to rat chromosome 13q24-->q26 and mouse chromosome 1H4-6 by FISH.

Animals↗
PubMed2000

Loss of heterozygosity analysis of 13q and 14q in human malignant mesothelioma.

Cytogenetic investigations of malignant mesothelioma (MM) have revealed frequent losses in chromosomes 13 and 14, suggesting that inactivation of tumor suppressor genes (TSGs) residing in these chromosomes may contribute to mesothelial cell tumorigenesis. To define the shortest region of overlap (SRO) of deletions from these chromosomes, we performed loss of heterozygosity (LOH) analyses on 30 MMs using 25 microsatellite markers in 13q and 21 markers in 14q. Twenty of the 30 MMs (67%) showed allelic loss of at least one marker in 13q. The SRO of deletions was delineated as an approximately 7 centiMorgan region, flanked by markers D13S1253 and D13S291, located at 13q13.3-14.2. Thirteen of the 30 MMs (43%) displayed allelic losses from 14q, with at least three distinct regions of LOH located at segments q11.2-13.2, q22.3-24.3, and q32. 12. These data highlight a single region of chromosomal loss in 13q in many MMs, implicating the involvement of a TSG that is critical to the pathogenesis of this malignancy. In contrast, the lower incidence and diffuse pattern of allelic losses in 14q suggest that several TSGs in this chromosome arm may contribute to tumorigenic progression in a subset of MMs. Genes Chromosomes Cancer 28:337-341, 2000.

Alleles↗
PubMed1999

Identification of a chromosome 3p14.3-21.1 gene, APPL, encoding an adaptor molecule that interacts with the oncoprotein-serine/threonine kinase AKT2.

AKT2 is a serine/threonine kinase implicated in human ovarian and pancreatic cancers. AKT2 is activated by a variety of growth factors and insulin via phosphatidylinositol 3-kinase (PI3K). However, its normal cellular role is not well understood. To gain insight into the function of AKT2, we performed yeast two-hybrid system to screen for interacting proteins. Using this technique, we identified a novel interactor, designated APPL, which contains a pleckstrin homology (PH) domain, a phosphotyrosine binding (PTB) domain and a leucine zipper, classes of motifs defined in signaling molecules as functional interaction domains with specific targets. The PH domain of APPL shows similarity to those found in GTPase-activating proteins such as oligophrenin-1 and Graf, whereas its PTB domain exhibits homology with CED-6, an adaptor protein that promotes engulfment of apoptotic cells, and IB1, a transactivator of the GLUT2 gene. APPL is highly expressed in skeletal muscle, heart, ovary and pancreas, tissues in which AKT2 mRNA is abundant. APPL interacts with the inactive form of AKT2; moreover, APPL binds to the PI3K catalytic subunit, p110alpha. These data suggest that APPL is an adaptor that may tether inactive AKT2 to p110alpha in the cytoplasm and thereby may expedite recruitment of AKT2 and p110alpha to the cell membrane upon mitogenic stimulation. Furthermore, the APPL gene was mapped to human chromosome 3p14.3-p21.1, where deletions and other rearrangements have often been reported in a variety of tumor types. The identification of APPL may facilitate further analysis of the physiological and oncogenic activities of AKT2.

Amino Acid Sequence↗
PubMed1999

Novel human and mouse annexin A10 are linked to the genome duplications during early chordate evolution.

We have identified and characterized a 12th subfamily of vertebrate annexins by systematic analysis of the primary structure, chromosomal mapping, and molecular evolution of unique cDNA and protein sequences from human and mouse. Distinctive features included rare expression, a codon deletion in conserved repeat 3, and an unusual ablation of the type II calcium-binding sites in tetrad core repeats 1, 3, and 4. The paralogy of novel annexin A10 (following revised nomenclature) was confirmed by FISH-mapping human ANXA10 to chromosome 4q33 and genetic linkage mapping mouse Anxa10 to midchromosome 8. Phylogenetic analysis established that the 5' and 3' halves of the annexin A6 octad are more closely related to annexins A5 and A10, respectively, than they are to each other. Molecular date estimates, paralogy linkage maps between human chromosomes 4 and 5, and annexin structural considerations led to the proposal that annexins A5 and A10 may have been the direct progenitors of annexin A6 octad formation via chromosomal duplication during the genome expansion in early chordates.

Amino Acid Sequence↗
PubMed1999

A new human synovial sarcoma cell line, HS-SY-3, with a truncated form of hybrid SYT/SSX1 gene.

Recent cytogenetical and molecular studies have indicated that synovial sarcoma harbors a t(X;18)(p11.2;q11.2) translocation, resulting in the formation of a hybrid SYT/SSX (SSX1 or SSX2) gene. We newly established a human cell line, HS-SY-3, from a synovial sarcoma. HS-SY-3 cells were shown to harbor the pathognomonic t(X;18)(p11.2;q11.2) translocation by chromosome analysis but not to exhibit the classical hybrid SYT/SSX transcripts induced by this translocation, using RT-PCR. To determine the reason for this discrepancy, we analyzed cDNA from HS-SY-3 cells, as well as the original sarcoma tissue by the rapid amplification of cDNA 3' end assay, and found that the chimaeric cDNA was 240 bp shorter than the previously established SYT/SSX1 cDNA due to truncation of the 3' side of SSX1. The HS-SY-3 cells should be useful for future functional studies of the SYT/SSX chimeric gene.

Aged↗
PubMed1999

Human annexin 31 genetic mapping and origin.

The cDNA encoding novel human annexin 31 was utilized for chromosomal mapping, structural comparison, and phylogenetic analysis to clarify its genetic relationship to other annexins. The ANX31 gene locus was mapped by fluorescence in situ hybridization to human chromosome 1q21, remote from ten other paralogous human annexins on different chromosomes but near the epidermal differentiation gene complex, the S100A gene cluster and a breast-cancer translocation region. Protein homology testing and characterization of incompletely processed expressed sequence tags identified annexin 2 as the closest extant homologue. Maximum likelihood analysis confirmed its most recent common ancestor with vertebrate annexin 2 and validated its classification, in order of discovery, as annexin 31. This subfamily was formed approx. 500-600millionyears ago, subsequent to the gene duplication that produced annexin 1. It has diverged relatively rapidly and extensively, and specifically in the well-conserved, functionally critical type II calcium-binding sites.

Animals↗
PubMed1999

Comparative genomic hybridization and loss of heterozygosity analyses identify a common region of deletion at 15q11.1-15 in human malignant mesothelioma.

Comparative genomic hybridization analysis was performed to identify chromosomal imbalances in 24 human malignant mesothelioma (MM) cell lines derived from untreated primary tumors. Chromosomal losses accounted for the majority of genomic imbalances. The most frequent underrepresented segments were 22q (58%) and 15q1.1-21 (54%); other recurrent sites of chromosomal loss included 1p12-22 (42%), 13q12-14 (42%), 14q24-qter (42%), 6q25-qter (38%), and 9p21 (38%). The most commonly overrepresented segment was 5p (54%). DNA sequence amplification at 3p12-13 was observed in two cases. Whereas some of the regions of copy number decreases (i.e., segments in 1p, 6q, 9p, and 22q) have previously been shown to be common sites of karyotypic and allelic loss in MM, our comparative genomic hybridization analyses identified a new recurrent site of chromosomal loss within 15q in this malignancy. To more precisely map the region of 15q deletion, loss of heterozygosity analyses were performed with a panel of polymorphic microsatellite markers distributed along 15q, which defined a minimal region of chromosomal loss at 15q11.1-15. The identification of frequent losses of a discrete segment in 15q suggests that this region harbors a putative tumor suppressor gene whose loss/inactivation may contribute to the pathogenesis of many MMs.

Chromosomes, Human, Pair 15↗
PubMed1999

Asbestos, chromosomal deletions, and tumor suppressor gene alterations in human malignant mesothelioma.

Exposure to the carcinogen asbestos is considered to be a major factor contributing to the development of most malignant mesotheliomas (MMs). We highlight the role of asbestos in MM and summarize cytogenetic and molecular genetic findings in this malignancy. The accumulation of numerous clonal chromosomal deletions in most MMs suggests a multistep process of tumorigenesis, characterized by the loss and/or inactivation of multiple tumor suppressor genes (TSGs). Cytogenetic and loss of heterozygosity (LOH) analyses of MMs have demonstrated frequent deletions of specific sites within chromosome arms 1p, 3p, 6q, 9p, 13q, 15q, and 22q. Furthermore, TSGs within two of these regions, i.e., p16/CDKN2A-p14ARF at 9p21 and NF2 at 22q12, are frequently altered in MMs. Homozygous deletion appears to be the major mechanism affecting p16/CDKN2A-p14ARF, whereas inactivating mutations coupled with allelic loss occur at the NF2 locus. Finally, recent studies have demonstrated the presence and expression of simian virus 40 (SV40) in many MMs. SV40 large T antigen has been shown to inactivate the TSG products Rb and p53, suggesting the possibility that asbestos and SV40 could act as cocarcinogens in MM. The frequent occurrence of homozygous deletions of p16/CDKN2A-p14ARF and the ability of SV40 Tag to bind TSG products suggest that perturbations of both Rb- and p53-dependent growth-regulatory pathways are critically involved in the pathogenesis of MM.

Asbestos↗
PubMed1999

Coexisting myelodysplasia and myeloproliferative features in a single clone containing 5q-, Ph and i(17q).

A case with myelodysplasia in which a single clone contained both 5q- and Ph chromosomes at diagnosis is presented. The patient subsequently developed leukocytosis and at that time was found to have acquired an additional chromosomal abnormality, i(17)(q10). This case illustrates the role of three different genetic changes that impart different clinical characteristics, i.e. myelodysplastic as well as myeloproliferative changes, as part of a multistep leukemogenic process.

Aged↗
PubMed1999

Cell cycle withdrawal promotes myogenic induction of Akt, a positive modulator of myocyte survival.

During myogenesis, proliferating myoblasts withdraw from the cell cycle, acquire an apoptosis-resistant phenotype, and differentiate into myotubes. Previous studies indicate that myogenic induction of the cyclin-dependent kinase inhibitor p21 results in an inhibition of apoptotic cell death in addition to its role as a negative cell cycle regulator. Here we demonstrate that the protein encoded by the Akt proto-oncogene is induced in C2C12 cells during myogenic differentiation with a corresponding increase in kinase activity. In differentiating cultures, expression of dominant-negative forms of Akt increase the frequency of cell death whereas expression of wild-type Akt protects against death, indicating that Akt is a positive modulator of myocyte survival. Antisense oligonucleotides against p21 block cell cycle withdrawal, inhibit Akt induction, and enhance cell death in differentiating myocyte cultures. Adenovirus-mediated transfer of wild-type or constitutively active Akt constructs confer partial resistance to cell death under conditions where cell cycle exit is blocked by the antisense oligonucleotides. Collectively, these data indicate that cell cycle withdrawal facilitates the induction of Akt during myogenesis, promoting myocyte survival.

Adenoviruses, Human↗
PubMed1999

Emerging translational therapies for mesothelioma.

Malignant pleural mesothelioma remains a therapeutic and diagnostic problem. Translational mechanisms for treatment of the disease are emerging from newly learned characteristics of the tumor on a molecular, cellular, and extracellular basis. Although slow to reach the clinical arena, these potential strategies do show proof of principle in the in vitro and in vivo settings, and some, including adenoviral molecular chemotherapy, have completed phase I testing. This review describes the rationale and status of these newer treatment ideas.

Adenoviridae↗