The cellular homologue of the transforming gene of SKV avian retrovirus maps to human chromosome region 1q22----q24

Novel factors that activate and deactivate cardiac fibroblasts: A new perspective for treatment of cardiac fibrosis

Heart disease with attendant cardiac fibrosis kills more patients in developed countries than any other disease, including cancer. We highlight the recent literature on factors that activate and also deactivate cardiac fibroblasts. Activation of cardiac fibroblasts results in myofibroblasts phenotype which incorporates aSMA to stress fibres, express ED-A fibronectin, elevated PDGFRα and are hypersecretory ECM components. These cells facilitate both acute wound healing (infarct site) and chronic cardiac fibrosis. Quiescent fibroblasts are associated with normal myocardial tissue and provide relatively slow turnover of the ECM. Deactivation of activated myofibroblasts is a much less studied phenomenon. In this context, SKI is a known negative regulator of TGFb₁ /Smad signalling, and thus may share functional similarity to PPARγ activation. The discovery of SKI's potent anti-fibrotic role, and its ability to deactivate and/or myofibroblasts is featured and contrasted with PPARγ. While myofibroblasts are typically recruited from pools of potential precursor cells in a variety of organs, the importance of activation of resident cardiac fibroblasts has been recently emphasised. Myofibroblasts deposit ECM components at an elevated rate and contribute to both systolic and diastolic dysfunction with attendant cardiac fibrosis. A major knowledge gap exists as to specific proteins that may signal for fibroblast deactivation. As SKI may be a functionally pluripotent protein, we suggest that it serves as a scaffold to proteins other than R-Smads and associated Smad signal proteins, and thus its anti-fibrotic effects may extend beyond binding R-Smads. While cardiac fibrosis is causal to heart failure, the treatment of cardiac fibrosis is hampered by the lack of availability of effective pharmacological anti-fibrotic agents. The current review will provide an overview of work highlighting novel factors which cause fibroblast activation and deactivation to underscore putative therapeutic avenues for improving disease outcomes in cardiac patients with fibrosed hearts.

SKI activates the Hippo pathway via LIMD1 to inhibit cardiac fibroblast activation

We have previously shown that overexpression of SKI, an endogenous TGF-β₁ repressor, deactivates the pro-fibrotic myofibroblast phenotype in the heart. We now show that SKI also functions independently of SMAD/TGF-β signaling, by activating the Hippo tumor-suppressor pathway and inhibiting the Transcriptional co-Activator with PDZ-binding motif (TAZ or WWTR1). The mechanism(s) by which SKI targets TAZ to inhibit cardiac fibroblast activation and fibrogenesis remain undefined. A rat model of post-myocardial infarction was used to examine the expression of TAZ during acute fibrogenesis and chronic heart failure. Results were then corroborated with primary rat cardiac fibroblast cell culture performed both on plastic and on inert elastic substrates, along with the use of siRNA and adenoviral expression vectors for active forms of SKI, YAP, and TAZ. Gene expression was examined by qPCR and luciferase assays, while protein expression was examined by immunoblotting and fluorescence microscopy. Cell phenotype was further assessed by functional assays. Finally, to elucidate SKI’s effects on Hippo signaling, the SKI and TAZ interactomes were captured in human cardiac fibroblasts using BioID2 and mass spectrometry. Potential interactors were investigated in vitro to reveal novel mechanisms of action for SKI. In vitro assays on elastic substrates revealed the ability of TAZ to overcome environmental stimuli and induce the activation of hypersynthetic cardiac myofibroblasts. Further cell-based assays demonstrated that SKI causes specific proteasomal degradation of TAZ, but not YAP, and shifts actin cytoskeleton dynamics to inhibit myofibroblast activation. These findings were supported by identifying the bi-phasic expression of TAZ in vivo during post-MI remodeling and fibrosis. BioID2-based interactomics in human cardiac fibroblasts suggest that SKI interacts with actin-modifying proteins and with LIM Domain-containing protein 1 (LIMD1), a negative regulator of Hippo signaling. Furthermore, we found that LATS2 interacts with TAZ, whereas LATS1 does not, and that LATS2 knockdown prevented TAZ downregulation with SKI overexpression. Our findings indicate that SKI’s capacity to regulate cardiac fibroblast activation is mediated, in part, by Hippo signaling. We postulate that the interaction between SKI and TAZ in cardiac fibroblasts is arbitrated by LIMD1, an important intermediary in focal adhesion-associated signaling pathways. This study contributes to the understanding of the unique physiology of cardiac fibroblasts, and of the relationship between SKI expression and cell phenotype.

Prognostic factors and genetic markers in thymoma

In this literature review prognostic factors and genetic markers that play a role in the staging of thymomas are discussed. The effect on prognosis of different factors, such as paraneoplastic syndromes, age, gender, classification, capsular invasion and surgical treatment, is evaluated. There is no generally accepted pathological classification of thymomas. More recently developed surgical techniques such as video-assisted or robotic thoracic surgery require longer follow-up times to determine whether they have equal long-term results compared to the classical surgical techniques. Many genetic markers have been described but at the present time no definite guidelines can be provided regarding screening and staging of thymomas.

The analysis of inconsistencies between cytogenetic annotations and sequence mapping by defining the imprecision zones of cytogenetic banding

MOTIVATION

In current databases, there are many genes with inconsistent mapping positions between their cytogenetic annotations and sequence map positions. However, not all inconsistencies are the same. Some of them may be problematic which should be corrected in the future; while others may result from the imprecise nature of chromosomal banding which may be tolerable. It is important to stratify the cytogenetic position information into different confidence groups with the recognition of the impreciseness of cytogenetic banding.

RESULTS

When plotting their cytogenetic annotations against sequence map positions on a 2D plane, the consistent genes tend to have a compact linear distribution; while genes with inconsistent positions are more scattered. The overlapping areas between these two groups are defined as the tolerable imprecision zones by linear regression and distance analysis. The system was implemented using sequence information from NCBI Map Viewer Build 36.3 and cytogenetic annotations from NCBI Entrez Gene. The genes' position information is classified into five confidence groups: inconsistent-intolerable, inconsistent-tolerable, consistent-imprecise, consistent-precise and consistent-rough. Using information from NCBI Map Viewer Build 36.3 and NCBI Entrez Gene, the percentages of these confidence groups are 1.4%, 7.0%, 54.0%, 35.4% and 2.2%, respectively. Using information from NCBI Map Viewer Build 36.3 and NCBI online Mendelian inheritance in man (OMIM), the percentages are 3.7%, 16.9%, 49.0%, 19.0% and 11.4%, respectively. Combining these two results, a confidence table of genes' position information was constructed.

AVAILABILITY

The detailed results are accessible over the Internet at http://centrallab.hosp.ncku.edu.tw/imz.

Expression of a novel Ski-like gene in Xenopus development

Members of the Ski/Sno family of gene products contain a characteristic peptide domain involved in protein-protein or protein-DNA interaction. Here, we characterize the developmental expression of xDawg, in Xenopus laevis, of a new gene, related to the Ski/Sno family of transcription regulators. The Ski/Sno domain of xDawg is predicted to present an electropositive surface, consistent with a role in DNA binding. This gene is expressed in the marginal zone of early gastrulae, and in the brain, sensory vesicles, and cranial neural crest of neurula and tailbud embryos.

The inv(16) fusion protein associates with corepressors via a smooth muscle myosin heavy-chain domain

Inversion(16) is one of the most frequent chromosomal translocations found in acute myeloid leukemia (AML), occurring in over 8% of AML cases. This translocation results in a protein product that fuses the first 165 amino acids of core binding factor beta to the coiled-coil region of a smooth muscle myosin heavy chain (CBFbeta/SMMHC). CBFbeta interacts with AML1 to form a heterodimer that binds DNA; this interaction increases the affinity of AML1 for DNA. The CBFbeta/SMMHC fusion protein cooperates with AML1 to repress the transcription of AML1-regulated genes. We show that CBFbeta/SMMHC contains a repression domain in the C-terminal 163 amino acids of the SMMHC region that is required for inv(16)-mediated transcriptional repression. This minimal repression domain is sufficient for the association of CBFbeta/SMMHC with the mSin3A corepressor. In addition, the inv(16) fusion protein specifically associates with histone deacetylase 8 (HDAC8). inv(16)-mediated repression is sensitive to HDAC inhibitors. We propose a model whereby the inv(16) fusion protein associates with AML1 to convert AML1 into a constitutive transcriptional repressor.

Molecular cytogenetic aberrations in CD30+ anaplastic large cell lymphoma cell lines

Anaplastic large cell lymphomas (ALCL) in children represent a heterogeneous group of neoplasms with regard to the cell lineages involved. The chromosomal 5q35 breakpoint (bp) and the expression of the NPM/ALK fusion gene are the most remarkable molecular cytogenetic features of these malignancies. To identify new locations of ALCL-related oncogenes, comparative genomic hybridization (CGH) was applied to three ALCL cell lines (SU-DHL-1, Karpas 299, and DEL) exhibiting the 5q35 bp and expressing the NPM/ALK transcript. The CGH profiles were compared with those obtained with DNA from U937, HL-60 cells, and altered lymph nodes from two children with ALCL. Significant DNA copy number gains and/or losses were observed on several chromosomes in all ALCL cell lines. Distinct amplicons were detected on 1q21 approximately q44 (DEL), 7q12 (SU-DHL-1), and 1q12 approximately q22 (Karpas 299) regions. The NPM/ALK fusion gene was confirmed by fluorescence in situ hybridization (FISH) analysis in more than 80% of interphase nuclei and metaphase spreads. Enhanced expression of TGF-beta2 and c-MET candidate genes located at the amplified regions was revealed in DEL and SU-DHL1 cell lines by Northern blot analysis. These findings delineate chromosomal imbalances in ALCL-derived cell lines in parallel with high level of amplification covering target DNA sequences, which could play a role in ALCL pathogenesis.

Suppressor and oncogenic roles of transforming growth factor-beta and its signaling pathways in tumorigenesis

Transforming growth factor-beta (TGF-beta) has been implicated in oncogenesis since the time of its discovery almost 20 years ago. The complex, multifunctional activities of TGF-beta endow it with both tumor suppressor and tumor promoting activities, depending on the stage of carcinogenesis and the responsivity of the tumor cell. Dysregulation or alteration of TGF-beta signaling in tumorigenesis can occur at many different levels, including activation of the ligand, mutation or transcriptional suppression of the receptors, or alteration of downstream signal transduction pathways resulting from mutation or changes in expression patterns of signaling intermediates or from changes in expression of other proteins which modulate signaling. New insights into signaling from the TGF-beta receptors, including the identification of Smad signaling pathways and their interaction with mitogen-activated protein (MAP) kinase pathways, are providing an understanding of the changes involved in the change from tumor suppressor to tumor promoting activities of TGF-beta. It is now appreciated that loss of sensitivity to inhibition of growth by TGF-beta by most tumor cells is not synonymous with complete loss of TGF-beta signaling but rather suggests that tumor cells gain advantage by selective inactivation of the tumor suppressor activities of TGF-beta with retention of its tumor promoting activities, especially those dependent on cross talk with MAP kinase pathways and AP-1.

Loss of the SKI proto-oncogene in individuals affected with 1p36 deletion syndrome is predicted by strain-dependent defects in Ski-/- mice

Experiments involving overexpression of Ski have suggested that this gene is involved in neural tube development and muscle differentiation. In agreement with these findings, Ski-/- mice display a cranial neural tube defect that results in exencephaly and a marked reduction in skeletal muscle mass. Here we show that the penetrance and expressivity of the phenotype changes when the null mutation is backcrossed into the C57BL6/J background, with the principal change involving a switch from a neural tube defect to midline facial clefting. Other defects, including depressed nasal bridge, eye abnormalities, skeletal muscle defects and digit abnormalities, show increased penetrance in the C57BL6/J background. These phenotypes are interesting because they resemble some of the features observed in individuals diagnosed with 1p36 deletion syndrome, a disorder caused by monosomy of the short arm of human chromosome 1p (refs. 6-9). These similarities prompted us to re-examine the chromosomal location of human SKI and to determine whether SKI is included in the deletions of 1p36. We found that human SKI is located at distal 1p36.3 and is deleted in all of the individuals tested so far who have this syndrome. Thus, SKI may contribute to some of the phenotypes common in 1p36 deletion syndrome, and particularly to facial clefting.

Novel genomic imbalances and chromosome translocations involving c-myc gene in Burkitt's lymphoma

In this study, CA46 and ST486, two Epstein-Barr (EBV) negative cell lines derived from sporadic BL, were analyzed by multicolor spectral karyotyping, G-banding, fluorescence in situ hybridization with single-copy gene probes, and comparative genomic hybridization (CGH). In addition to reciprocal t(8;14)(q24;q32) translocation involving c-myc and IgH loci, we identified a t(7;8;14)(q11.2;q24;q32) translocation in CA 46 cells and t(8;14;18)(q24;q32;q23) in ST486 cells. Both rearrangements were not previously described in BL and resulted in transposition of myc sequences in a new genomic configuration. Several DNA imbalances mapped by CGH at the same sites in both lines, may reflect recurrent genomic changes that are relevant to pathogenesis of BL. We tested the tumorigenicity of these lines by injecting cells intraperitoneally in SCID mice. In two separate experiments, CA46 cells produced tumors 2 weeks after cell inoculation while ST486 cells induced only one tumor after a long latency period. Partial duplication of the long arm of chromosome 1 involving variable bands but always band 1q23 is the second most common alteration in BL and is known to be associated with aggressive tumors and poor prognosis. Duplication of the bands 1q23-24 commonly observed in EBV-negative lines was identified only in highly tumorigenic CA46 cells suggesting that this region harbor gene(s) associated with tumor cell invasiveness.

Recurrent genetic aberrations in thymoma and thymic carcinoma

Apart from single reported aberrant karyotypes, genetic alterations in thymic epithelial neoplasms have not been investigated so far. In this study, 12 World Health Organization classification type A thymomas (medullary thymomas), 16 type B3 thymomas (well-differentiated thymic carcinomas), and nine type C thymomas, all of them primary thymic squamous cell carcinomas, were analyzed by comparative genomic hybridization and fluorescence in situ hybridization. With the exception of one single case, type A thymomas did not reveal chromosomal gains or losses in comparative genomic hybridization. In contrast, all type B3 thymomas showed chromosomal imbalances, with gain of 1q, loss of chromosome 6, and loss of 13q occurring in 11 (69%), six (38%), and five (31%) of 16 cases, respectively. In primary thymic squamous cell carcinoma, the most frequent chromosomal losses were observed for 16q (six of nine cases, 67%), 6 (4 of 9, 44%), and 3p and 17p (three of nine each, 33%), whereas recurrent gains of chromosomal material were gains of 1q (5 of 9, 56%), 17q, and 18 (three of nine each, 33%). This study shows that the distinct histological thymoma types A and B3 exhibit distinct genetic phenotypes, whereas type B3 thymoma and primary thymic squamous cell carcinoma partially share genetic aberrations. In addition to the possible tumorigenic role, the deletion in type B3 thymoma of chromosome 6, harboring the HLA locus, might play a role in the pathogenesis of paraneoplastic autoimmunity characteristic of thymoma.

MUC1 is activated in a B-cell lymphoma by the t(1;14)(q21;q32) translocation and is rearranged and amplified in B-cell lymphoma subsets

The band 1q21 is among the most common sites affected by chromosomal translocations in lymphoid, myeloid, epithelial, and sarcomatous lesions. In non-Hodgkin's lymphoma (NHL), translocations and duplications affecting this chromosomal site are frequently, but not exclusively, seen in association with primary abnormalities such as the t(14;18)(q32;q21) and t(8;14)(q24;q32) translocations, suggesting a role for 1q21 rearrangements in tumor progression. We report here the characterization and cloning of breakpoints in a case of extranodal ascitic B-cell lymphoma with a t(1;14)(q21;q32) translocation. The breakpoints on the der(1) and der(14) chromosomes were mapped by fluorescence in situ hybridization and Southern blot analysis and cloned using an IGHG (Cγ) probe. The translocation linked theIGHG4 switch (Sγ4) sequences of the productively rearranged allele to chromosome 1 sequences downstream of MUC1, leaving the MUC1 transcriptional unit intact. MUC1 was markedly overexpressed in the tumor at the mRNA and protein levels relative to lymphoma cell lines lacking a 1q21 rearrangement. Presumably,MUC1 transcription is aberrantly regulated by the IGHA(C) 3′ enhancer element retained on the same chromosome. Screening of a panel of B-cell lymphomas by Southern blot analysis identified a subset with a 3′ MUC1 breakpoint and another with low-level amplification of MUC1. MUC-1 mucin has previously been shown to be frequently overexpressed in human epithelial cancers and to be associated with tumor progression and poor clinical outcome. Thus, MUC1 activation by chromosomal translocation, rearrangement, and amplification, identified here for the first time in NHL, is consistent with its suggested role in tumorigenesis.

MUC1 is activated in a B-cell lymphoma by the t(1;14)(q21;q32) translocation and is rearranged and amplified in B-cell lymphoma subsets

The band 1q21 is among the most common sites affected by chromosomal translocations in lymphoid, myeloid, epithelial, and sarcomatous lesions. In non-Hodgkin's lymphoma (NHL), translocations and duplications affecting this chromosomal site are frequently, but not exclusively, seen in association with primary abnormalities such as the t(14;18)(q32;q21) and t(8;14)(q24;q32) translocations, suggesting a role for 1q21 rearrangements in tumor progression. We report here the characterization and cloning of breakpoints in a case of extranodal ascitic B-cell lymphoma with a t(1;14)(q21;q32) translocation. The breakpoints on the der(1) and der(14) chromosomes were mapped by fluorescence in situ hybridization and Southern blot analysis and cloned using an IGHG (Cγ) probe. The translocation linked theIGHG4 switch (Sγ4) sequences of the productively rearranged allele to chromosome 1 sequences downstream of MUC1, leaving the MUC1 transcriptional unit intact. MUC1 was markedly overexpressed in the tumor at the mRNA and protein levels relative to lymphoma cell lines lacking a 1q21 rearrangement. Presumably,MUC1 transcription is aberrantly regulated by the IGHA(C) 3′ enhancer element retained on the same chromosome. Screening of a panel of B-cell lymphomas by Southern blot analysis identified a subset with a 3′ MUC1 breakpoint and another with low-level amplification of MUC1. MUC-1 mucin has previously been shown to be frequently overexpressed in human epithelial cancers and to be associated with tumor progression and poor clinical outcome. Thus, MUC1 activation by chromosomal translocation, rearrangement, and amplification, identified here for the first time in NHL, is consistent with its suggested role in tumorigenesis.

Jumping translocation of 1q as the sole aberration in a case of follicular lymphoma

Cytogenetic and fluorescence in situ hybridization (FISH) studies in a case of follicular lymphoma grade III showed a "jumping translocation" of chromosome 1q21-qter to chromosomes Xq28 and 18q23, which resulted in a partial trisomy 1q as the only chromosome aberration. This case represents, to the best of our knowledge, the first report of a jumping translocation in a malignant lymphoma occurring as the sole aberration.

Human tenascin-R. Complete primary structure, pre-mRNA alternative splicing and gene localization on chromosome 1q23-q24

We have established the primary structure of human tenascin-R (TN-R), a component of the extracellular matrix of the central nervous system, by sequencing cDNA clones which cover its complete coding region. The deduced amino acid sequence of human TN-R (1358 amino acids) showed a homology to chicken and rat TN-R of 75 and 93%, respectively. By reverse transcriptase-polymerase chain reaction we have studied the existence of TN-R isoforms generated by pre-mRNA alternative splicing in various human astrocytomas and meningiomas. Our findings demonstrate the existence of a human isoform in which one fibronectin-like repeat is omitted. Northern blot analysis of the poly(A)-rich RNA from different tissues showed two mRNAs having sizes of about 10 and 11 kilobases. Using DNA from a panel of human-hamster and human-mouse somatic cell hybrids and by fluorescence in situ hybridization, we have assigned the gene for human TN-R to the region 1q23-q24. The mouse mutation loop-tail (Lp), which has been proposed as a model for human neural tube defects, maps to region of mouse chromosome 1 syntenic with human 1q23-q24.

High frequency of EBV association with non-random abnormalities of the chromosome region 1q21-25 in AIDS-related Burkitt's lymphoma-derived cell lines

Chromosome 1q abnormalities represent the second most frequent cytogenetic lesion of Burkitt lymphoma (BL) and acute lymphoblastic leukemia (ALL)-L3. The most frequent change is partial duplication of the long arm of chromosome 1, involving variable bands but consistently including 1q23. Among AIDS-related BL similar chromosome 1q abnormalities have also been found. We have now characterized in detail the chromosome 1q abnormalities of 4 AIDS-BL cell lines and compared them to other molecular features of the tumor clone, namely infection by Epstein Barr virus (EBV). Immunophenotypic characteristics were also assessed by conventional in situ immunocytochemical and flow cytometric procedures. The B-cell origin of all cell lines was demonstrated by the expression of B-cell-restricted markers (e.g., CD19). Analysis of Ig light chains confirmed their monoclonal nature. The t(8;14) was present in 3 of the 4 lines, whereas variant translocation t(8;22) was detected in the remaining cell line. Additional chromosomal changes were found in all cases, with chromosome 1 being involved in all. Structural changes encompassed in each case the 1q21-25 bands, in either duplication or partial trisomy. EBER ISH studies identified EBV association in 3 of the 4 AIDS-BL cell lines in contrast to previous studies of BL of immunocompetent individuals. Our findings of a high frequency of chromosome 1q abnormalities in EBV-infected AIDS-related BL cell lines demonstrate that such chromosomal abnormality and EBV positivity are not mutually exclusive and are possibly independent factors, whereas their close association in AIDS may be related to the immunodeficiency.

Jumping translocations of 1q in Burkitt lymphoma and acute nonlymphocytic leukemia

"Jumping translocations" have been observed mostly in cultured cells. Reports of such translocations in hematologic malignancies are few, and the associated clinical picture is unclear. We report three cases of hematologic malignancies with various unbalanced translocations (so-called jumping translocation) involving trisomy of the long arm of chromosome 1. The first case was a 13-year-old boy with Burkitt lymphoma who showed a very aggressive clinical course. The second case was a 10-month-old girl with acute nonlymphocytic leukemia [ANNL, French-American-British (FAB) classification M0] who had high risk factors, including hyperleukocytosis with a peripheral white blood cell (WBC) count of 300,000/microliters, and who died 7 months after diagnosis. The third case was a 6-year-old boy with Burkitt-like leukemia whose first remission lasted only 1 month. Only 10 cases with jumping translocations, including two cases with Burkitt-like leukemia/lymphoma, have been reported previously. This rare phenomenon may occur with increased frequency in Burkitt-like leukemia/lymphoma and may be an adverse prognostic factor.

A lineage-specific t(1;14)(q21;q32) as an early event in development of B-cell clonal expansion

We report a patient in whom a cell line of 47,XY,+X,t(1;14)(q21;q32) constitution was found in a lymph node excised from the neck. Histologic examination and immunophenotyping both in situ and by flow cytometry failed to confirm a diagnosis of B-cell lymphoma, but Southern analysis indicated the presence of B-cell clonal expansion. These observations support the concept that primary chromosomal abnormalities occur in clonal expansions in the very earliest stages of tumorigenesis.

Structure of the gene encoding CD34, a human hematopoietic stem cell antigen

CD34 is a cell surface antigen of unknown function expressed in humans in hematopoietic stem cells, vascular endothelium, and blasts from 30% of patients with acute myeloid and lymphocytic leukemia. To begin to investigate the cis-acting elements required for this tissue-specific expression, the human CD34 locus was isolated and its genomic structure and transcriptional start site were characterized. The human CD34 gene spans 26 kb and has 8 exons, a structure quite similar to that of the murine gene. The start site of CD34 transcription was determined to be 258 bp upstream of the translational start site using RNase protection. These experiments also indicated that the 5' untranslated region has extensive secondary structure. In addition, fluorescence in situ hybridization was used to map the CD34 locus to band 1q32.

Molecular cloning and expression of the type 1 and type 2 murine receptors for tumor necrosis factor

Clones encoding the type 1 (p80) and type 2 (p60) forms of the murine receptors for tumor necrosis factor (TNF) were isolated by cross-hybridization using probes derived from the cloned human TNF receptors. Each of the murine receptors shows strong sequence homology to the corresponding human receptor (approximately 65% amino acid identity) throughout the molecule but only modest homology, limited to ligand-binding domains, between themselves. The ligand-binding characteristics of the recombinant murine receptors mirror those of the human homologs: both receptor types bind TNF-alpha and -beta with multiple affinity classes, and the ligands cross-compete. Analysis of the murine transcripts encoding these receptors revealed the presence of RNAs for one or both forms of the receptors in all cells examined. It was also demonstrated that for both types of human TNF receptor, variably sized transcripts are observed in different cells. The murine cDNAs were further used to determine the chromosomal locations of the TNF receptor genes. They are not linked, in contrast to the ligands, and map to chromosomes 4 (type 1) and 6 (type 2).

Molecular cloning and expression of the type 1 and type 2 murine receptors for tumor necrosis factor

Clones encoding the type 1 (p80) and type 2 (p60) forms of the murine receptors for tumor necrosis factor (TNF) were isolated by cross-hybridization using probes derived from the cloned human TNF receptors. Each of the murine receptors shows strong sequence homology to the corresponding human receptor (approximately 65% amino acid identity) throughout the molecule but only modest homology, limited to ligand-binding domains, between themselves. The ligand-binding characteristics of the recombinant murine receptors mirror those of the human homologs: both receptor types bind TNF-alpha and -beta with multiple affinity classes, and the ligands cross-compete. Analysis of the murine transcripts encoding these receptors revealed the presence of RNAs for one or both forms of the receptors in all cells examined. It was also demonstrated that for both types of human TNF receptor, variably sized transcripts are observed in different cells. The murine cDNAs were further used to determine the chromosomal locations of the TNF receptor genes. They are not linked, in contrast to the ligands, and map to chromosomes 4 (type 1) and 6 (type 2).

Establishment and characterization of a childhood pre-B acute lymphoblastic leukemia cell line, PER-278, with chromosome translocations t(1;19) and t(1;9)

Cell line PER-278 was established from a bone marrow sample of a 10-year-old boy diagnosed with pre-B acute lymphoblastic leukemia (ALL). PER-278 cells show the pre-B phenotype, express cytoplasmic Ig, and exhibit two translocations: t(1;19)(q23;p13) and t(1;9)(q23;p13). Assessment of the immunoglobulin rearrangements confirmed the clonal origin of cell line PER-278, and comparison with the patients's leukemic cells showed an identical pattern: loci involved at the breakpoint on chromosome 1 code for the oncogene SKI and for the Fc receptor II and on chromosome 19 for the insulin receptor. The t(1;19) may contribute to the malignant transformation in leukemic cells of pre-B phenotype.

Partial trisomy 1q in idiopathic myelofibrosis

Three cases of idiopathic myelofibrosis with partial trisomy of the long arm of chromosome 1 are described. Partial trisomy 1q was the only karyotypic change detectable in unstimulated peripheral blood cell cultures of one and bone-marrow cultures of two patients at diagnosis. The extra segment from chromosome 1 was located on different karyotype sites, i.e. 1qter, 1p34 and 6p22-23; 1q21-32 was the shortest overlapping region and the only trisomic segment in one of the three patients. These findings suggest that partial trisomy 1q is a primary chromosome aberration in myelofibrosis relevant in the pathogenesis of this hematologic disorder.

Abnormalities of chromosome 1 in relation to human malignant diseases

Chromosome 1 is known to often be involved in various malignant diseases. Its numerical and structural aberrations have been observed in chronic and acute leukemias and solid tumors as well. Recently five protooncogenes have been assigned to the long and short arms of chromosome 1. The frequent and nonspecific occurrence of chromosome 1 rearrangements in human tumors suggests that they play an important role in the pathogenesis and progression of these diseases. The frequency, types, and time of the occurrence of chromosome 1 aberrations and their relation to the stage of the disease were studied in 317 patients with various malignant diseases. In ten patients nonrandom aberrations of chromosome 1 were observed. Two patients had CML, two PRV followed by ANLL, and the remaining six patients suffered from ANLL, ALL, Burkitt lymphoma, MF, SMMoL, and IRSA, respectively. In six patients, total or partial trisomy of the long arm or of the whole chromosome 1 was present, and in three cases balanced translocations involving chromosome 1 could be found. In the cells of one patient a duplication of the centromeric heterochromatin was seen. We analyzed the breakpoints involved. Finally, the aberrations of chromosome 1 were almost always be observed at the terminal stage of the diseases.

The gene for enhancer binding proteins E12/E47 lies at the t(1;19) breakpoint in acute leukemias

The gene (E2A) that codes for proteins with the properties of immunoglobulin enhancer binding factors E12/E47 was mapped to chromosome region 19p13.2-p13.3, a site associated with nonrandom translocations in acute lymphoblastic leukemias. The majority of t(1;19)(q23;p13)-carrying leukemias and cell lines studied contained rearrangements of E2A as determined by DNA blot analyses. The rearrangements altered the E2A transcriptional unit, resulting in the synthesis of a transcript larger than the normal-sized E2A mRNAs in one of the cell lines with this translocation. These observations indicate that the gene for a transcription factor is located at the breakpoint of a consistently recurring chromosomal translocation in many acute leukemias and suggest a direct role for alteration of such factors in the pathogenesis of some malignancies.

The variable hematologic expression of the BCR-ABL genomic mutation and its possible determinants

The Philadelphia (Ph) chromosome usually results from the t(9;22), which causes the physical association of the BCR1 and ABL genes and their function as a single new gene. This precise genomic mutation probably has a significant role in the development of leukemia in humans, but that leukemia may take several forms: chronic myeloid leukemia (CML), acute myeloid leukemia, acute lymphocytic leukemia, and essential thrombocythemia; CML also transforms to a lymphoid or myeloid acute phase. Two models are considered with regard to determinants of this variable hematologic expression of BCR-ABL. The first is variation in the breakpoint site of BCR1. Two breakpoint sites, M-BCR and m-BCR, are known, and their occurrence shows a nonrandom association with the different forms of leukemia. The precise position of the breakpoint within M-BCR may also be important. The second model concerns the role of other genes in determining the leukemic form shown by BCR-ABL. Results are reviewed of a patient who entered blast crisis CML and whose leukemic clones involved ten genetic loci with known leukemic associations. Many of these were probably genetic variants that allowed leukemic proliferations following the initiation of blast crisis. The multiplicity of these genes may obscure the prime determinant of blast crisis, which is unknown at the present time.

Possible involvement of chromosome 1 in in vitro immortalization: evidence from progression of a human adenoma-derived cell line in vitro

We have previously reported that continuous in vitro passage in the presence of 3T3 feeders of a non-tumorigenic adenoma-derived epithelial cell line, designated PC/AA, resulted in its becoming immortal. At early passage PC/AA was normal diploid, whereas every cell of PC/AA late passage had an isochromosome 1(q) which led us to suggest that abnormalities of chromosome 1 may be involved in tumour progression. We now report the isolation of a 3T3-feeder-independent variant of early-passage PC/AA, designated PC/AA/FI, which was immortal in vitro and remained non-tumorigenic. Each cell of PC/AA/FI again has an isochromosome 1(q), like the late-passage PC/AA. However, with PC/AA/FI it is the other chromosome 1 of the homologous pair which is involved in the formation of the isochromosome 1(q). This is possible to determine because of the polymorphic centromeric heterochromatin on chromosome 1 of the early-passage PC/AA. With the late-passage PC/AA (grown with 3T3 feeders) the homologue with the large C-band has given rise to an isochromosome 1(q) whereas with PC/AA/FI it is the other homologue with the smaller C-band which has given rise to this isochromosome. Both the immortal PC/AA/FI and the immortal PC/AA late passage, therefore, have independent abnormalities involving chromosome 1. These results indicate that chromosome 1 may be involved in in vitro immortalization.

Chromosome 1 abnormalities in cervical carcinoma

Abnormalities of chromosome 1 have been reported in a number of solid tumors and hematologic malignancies, indicating that this is a frequent event in neoplasia. Here we report our observations on aberrations of chromosome 1 in malignancies of the uterine cervix. Tumor material obtained from 148 patients with invasive carcinoma of the cervix and two cases of carcinoma in situ (CIS) was analyzed on direct preparations by G-banding. The results showed abnormalities of chromosome 1 to be one of the most common karyotypic changes, with 95% of the patients showing rearrangements of this chromosome. These changes were never seen as the sole abnormality but were always found in association with other chromosomal aberrations. Numerical rearrangements were present in 54% of the cases, with losses of unaltered chromosome 1 predominating. Consistent marker chromosomes included deletions of chromosome 1 at bands q32, p34, q42, p32, and p22, isochromosomes of both the "p" and "q" arms and translocations, particularly on the long arm. Specific regions on both arms of chromosome 1 (1p11-p13 and 1q21-q32) were preferentially overrepresented in changes involving this chromosome. Certain breakpoints were nonrandomly involved in the structural changes, particularly band 1q32 breaks occurring at this site in 88 instances. The presence of chromosome 1 aberrations in the two cases of CIS suggests that rearrangements of this chromosome are not always a secondary change contributing to the progression of the cancer, but also may represent an early cytogenetic event as in neuroblastoma, some leukemias, and myeloproliferative disorders.

Tubulovillous adenoma of the colon with hyperdiploidy, double-minute chromosomes, and inversion of chromosome 1

A sessile adenoma of the left flexure of the colon was studied after surgical colectomy. Specimens were obtained for complete histologic evaluation. The tumor consisted of glandular tubes with decreased mucin production and a papillary structure on the luminal aspect. The muscularis mucosa was not involved; there was no carcinomatous focus. Cytogenetic study was carried out on 56 cells; none was normal, 77% were hyperdiploid (52-87 chromosomes), 16% were hypodiploid (18-39 chromosomes), and 7% were paradiploid. The supernumerary chromosomes were chromosomes #3, #6, #13, #19, and #20; chromosome #18 was missing in 80% of the cells. A marker for chromosome #1 resulting from a q21.1-q21.2 break with inversion of the centromere-bearing segment (pter-q21) was observed in 58% of the cells. Twenty-five percent of the cells had double minute chromosomes. Despite the histologically benign nature of the tumor, all the cells showed significant cytogenetic aberrations, some of which are considered to be markers of neoplastic transformation (polyploidy, double minutes, chromosome #1 marker).

Localization of the gene encoding human factor V to chromosome 1q21-25

The gene encoding human coagulation Factor V (FV), one of the cofactors in the blood clotting process, has been mapped to chromosome 1 by both Southern hybridization to DNA from human-hamster somatic cell hybrids and in situ hybridization. The whole plasmid pUC3A containing a 1.5-kb cDNA sequence for FV was 32P-labeled for Southern analysis and 3H-labeled for in situ hybridization to metaphase chromosomes. The results localized the FV gene to the region of 1q21-25.

Establishment and characterization of a human lymphoma cell line (WSU-NHL) with 14;18 translocation

The WSU-NHL cell line was established from a malignant pleural effusion occurring in a 46-yr-old female with nodular histiocytic (follicular, large cell) lymphoma. The established cells grow in clumps with a doubling time of 57 h. On light microscopy, cells exhibited primitive lymphoblastoid morphologic features with few cytoplasmic blebs. DNA histogram generated by flow cytometry indicated a hypodiploid stemline (0.93). Immunologic study revealed a mature B-cell phenotype with surface and cytoplasmic IgG lambda and reactivity with monoclonal antibodies to B-cell antigens (B1, B4, BL1, BL3, BL4, BL7, HLA-DR, CALLA and Leu-10). The cells were negative for T-cell and myeloid-monocyte antigens as well as Epstein-Barr virus nuclear antigen (EBNA). Cytogenetic analysis revealed 45,XX metaphases with complex abnormalities including t(14;18) (q32;q21). The phorbol ester, 12-O tetradecanoylphorbol 13 acetate (TPA) (1.6 x 10(-8) M) and interferon gamma (IFN-gamma) (500 U/ml) inhibited cell growth and induced differentiation to a more mature phenotype. The WSU-NHL cell line provides a continuous source of cells for molecular and immunologic studies of human lymphoma as well as the regulation of its growth and differentiation by biologic agents.