Evidence for the involvement of GM-CSF and FMS in the deletion (5q) in myeloid disorders

Loss of 5q in myeloid malignancies - A gain in understanding of biological and clinical consequences

Hemizygous interstitial or terminal deletion of the long arm of chromosome 5 [del(5q)] is a recurrent cytogenetic abnormality in myeloid malignancies, including myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). These deletions cause loss of a large contiguous chromosomal region encompassing more than 30 genes, which results in disease through haploinsufficiency of one or more genes including RPS14. In MDS, del(5q) in isolation is a lower-risk cytogenetic anomaly and is sometimes associated with a unique clinicopathological phenotype, but in AML it represents a higher-risk lesion, often denoting secondary AML arising from prior MDS. Lenalidomide effectively targets the del(5q)-bearing clone in MDS, resulting in sustained erythroid transfusion independence in most patients and cytogenetic remission in a subset of treated patients. Since the initial regulatory approval of lenalidomide for del(5q) MDS in 2005, translational research endeavors in del(5q)-associated myeloid malignancies have improved our understanding of how allelic haploinsufficiency underlies both the hematological phenotype and selective sensitivity to lenalidomide therapy. This review will focus on the molecular pathogenesis of del(5q) in myeloid malignancies, clinical development of lenalidomide and emerging data on lenalidomide-refractory del (5q) MDS, and possible novel targeted therapeutic strategies.

In silico analyses of CD14 molecule reveal significant evolutionary diversity, potentially associated with speciation and variable immune response in mammals

The cluster differentiation gene (CD14) is a family of monocyte differentiating genes that works in conjunction with lipopolysaccharide binding protein, forming a complex with TLR4 or LY96 to mediate innate immune response to pathogens. In this paper, we used different computational methods to elucidate the evolution of CD14 gene coding region in 14 mammalian species. Our analyses identified leucine-rich repeats as the only significant domain across the CD14 protein of the 14 species, presenting with frequencies ranging from one to four. Importantly, we found signal peptides located at mutational hotspots demonstrating that this gene is conserved across these species. Out of the 10 selected variants analyzed in this study, only six were predicted to possess significant deleterious effect. Our predicted protein interactome showed a significant varying protein-protein interaction with CD14 protein across the species. This may be important for drug target and therapeutic manipulation for the treatment of many diseases. We conclude that these results contribute to our understanding of the CD14 molecular evolution, which underlays varying species response to complex disease traits.

Role of Granulocyte-Macrophage Colony-Stimulating Factor in Acute Myeloid Leukemia/Myelodysplastic Syndromes

PURPOSE

Granulocyte-macrophage colony-stimulating factor (GM-CSF) cytokine stimulates growth, differentiation, and function of myeloid progenitors. We aimed to study the role of GM-CSF gene expression, its protein, and antibodies in patients with acute myeloid leukemia/myelodysplastic syndromes (AML/MDS) and their correlation to disease behavior and treatment outcome. The study included 50 Egyptian patients with AML/MDS in addition to 20 healthy volunteers as control subjects.

PATIENTS AND METHODS

Assessment of GM-CSF gene expression was performed by quantitative real-time polymerase chain reaction. GM-CSF proteins and antibodies were assessed by enzyme-linked immunosorbent assay.

RESULTS

There was significant decrease in GM-CSF gene expression ( P = .008), increase in serum level of GM-CSF protein ( P = .0001), and increase in anti-GM-CSF antibodies ( P = .001) in patients with AML/MDS compared with healthy control subjects. In addition, there was a significant negative correlation between serum levels of GM-CSF protein and initial peripheral blood blasts, percentage as well as response to therapy.

CONCLUSION

Any alteration in GM-CSF gene expression could have implications in leukemogenesis. In addition, GM-CSF protein serum levels could be used to predict outcome of therapy. GM-CSF antibodies may also play a role in the pathogenesis of AML/MDS. The use of these GM-CSF parameters for disease monitoring and as markers of disease activity needs further research.

Recent advances in the characterization of genetic factors involved in human susceptibility to infection by schistosomiasis

Human resistance to infection by schistosomes is associated to a strong Th2 immune. However a persistent Th2 response can cause severe kidney and liver disease in human. In this review, we mainly focused on the control of infection levels caused by schistosomes. Several experimental models allowed us to better understand the immunological mechanisms of the host against schistosome infection. High IgE and eosinophil levels are associated with resistance to infection by schistosomes and this effect is counterbalanced by IgG4. IgE and eosinophils are highly dependent on IL-4, IL-13, and Il-5, which are three main Th2 cytokines. We also examined the genetic factors involved in human susceptibility to infection by schistosomiasis. Infection levels are mainly regulated by a major locus SM1, in 5q31-q33 region, which contains the genes encoding for the IL-4, IL-13, and Il-5 cytokines. An association between an IL13 polymorphism, rs1800925, and infection levels has been shown. This polymorphism synergistically acts with another polymorphism (rs324013) in the STAT6 gene, encoding for the signal transducer of the IL13 pathway. This pathway has also been involved in atopic disorders. As helminthiasis, atopy is the result of aberrant Th2 cytokine response to allergens, with an increased production of IL-4, IL-13, Il-9 and Il-5, with high amounts of allergen-specific and total IgE and eosinophilia. However, the Th2 immune response is protective in helminthiasis but aggravating in atopic disorders. Several studies reported interplay between helminthic infections and allergic reactions. The different results are discussed here.

Advances in the 5q- syndrome

The 5q- syndrome is the most distinct of all the myelodysplastic syndromes with a clear genotype/phenotype relationship. The significant progress made during recent years has been based on the determination of the commonly deleted region and the demonstration of haploinsufficiency for the ribosomal gene RPS14. The functional screening of all the genes in the commonly deleted region determined that RPS14 haploinsufficiency is the probable cause of the erythroid defect in the 5q- syndrome. A mouse model of the human 5q- syndrome has now been created by chromosomal engineering involving a large-scale deletion of the Cd74-Nid67 interval (containing RPS14). A variety of lines of evidence support the model of ribosomal deficiency causing p53 activation and defective erythropoiesis, including most notably the crossing of the "5q- mice" with p53-deficient mice, thereby ameliorating the erythroid progenitor defect. Emerging evidence supports the notion that the p53 activation observed in the mouse model may also apply to the human 5q- syndrome. Other mouse modeling data suggest that haploinsufficiency of the microRNA genes miR-145 and miR-146a may contribute to the thrombocytosis seen in the 5q- syndrome. Lenalidomide has become an established therapy for the 5q- syndrome, although its precise mode of action remains uncertain.

Deletion 5q in myelodysplastic syndrome: a paradigm for the study of hemizygous deletions in cancer

Hemizygous deletions are common molecular abnormalities in cancer. In some cases, these deletions highlight chromosomal loci containing tumor suppressor genes that undergo homozygous inactivation. In other cases, hemizygous deletions cause disease by allelic insufficiency for one or more genes. As the intact allele has no identifiable lesions, functional approaches are critical for the identification of pathogenic genes within large deletions. Hemizygous, interstitial deletion of chromosome 5q is the most common cytogenetic abnormality in myelodysplastic syndrome (MDS) and has been the focus of functional analysis. Some patients with this molecular lesion have the 5q- syndrome, a disorder with a highly consistent clinical phenotype. A systematic RNA interference screen to interrogate the function of each gene in the common deleted region (CDR) for the 5q- syndrome identified RPS14 as a critical haploinsufficiency disease gene for the erythroid failure, which is a characteristic of this syndrome. Genes located in an adjacent deleted region have also been implicated in MDS. The full clinical phenotype is likely caused by the integration of effects from allelic insufficiency for multiple genes. With the identification and characterization of these genes, the 5q deletion is becoming a model for understanding hemizygous chromosomal deletions in cancer.

High titer autoantibodies to GM-CSF in patients with AML, CML and MDS are associated with active disease

Antibodies to granulocyte-macrophage colony-stimulating factor (GM-CSF) can be induced when GM-CSF is used as an adjuvant to solid tumor vaccination. Neutralizing anti-GM-CSF IgG has been associated with pulmonary alveolar proteinosis (PAP), and secondary PAP has been linked to myeloid leukemia. We studied 69 patients with acute myeloid leukemia, chronic myeloid leukemia and myelodysplastic syndrome, including 19 patients who received GM-CSF with peptide antigen and incomplete Freund's adjuvant in a vaccine trial for the presence or induction of anti-GM-CSF antibodies. Anti-GM-CSF IgG were present in 36 (52%) patients with myeloid leukemia compared to only 1 of 33 (3%) healthy subjects (P=0.008) and in none of 6 patients with lymphoid leukemia (P=0.0001). Antibody titers were unaffected by vaccination. Anti-GM-CSF IgA and IgM were found in 33 and 20% of patients, respectively; IgA from two patients neutralized GM-CSF. Strikingly, while anti-GM-CSF IgG titers were higher in patients with active disease (n=52) versus those in complete remission (n=14, P=0.0009), GM-CSF expression was not increased in either group. These data are first to show that anti-GM-CSF antibodies of multiple isotypes are present in patients with active myeloid leukemia without PAP and may be useful markers of disease activity.

The role of lenalidomide in the treatment of patients with chromosome 5q deletion and other myelodysplastic syndromes

PURPOSE OF REVIEW

The aim of this article is to discuss the relevant pathobiologic effects of lenalidomide and the most recent clinical evidence to support its use in patients with myelodysplastic syndrome.

RECENT FINDINGS

Lenalidomide is an immunomodulatory agent with biological activity in several hematologic malignancies, including myelodysplastic syndrome. The precise mechanism yielding benefit in patients with myelodysplastic syndrome and 5q- syndrome is not clear, but various molecular and pathogenic targets have been identified. Enhancement of cellular immunity through T-cell and NK-cell activation and suppression of inflammatory cytokines and pro-angiogenic peptides upon lenalidomide treatment has been demonstrated in in-vitro models of myelodysplastic syndrome. Furthermore, lenalidomide induces a direct cytotoxic effect against 5q- clones in leukemia cell lines and enhances ligand-induced erythropoietin receptor signaling in erythroid progenitors. Clinical trials with lenalidomide in myelodysplastic syndrome have supported the in-vitro evidence of karyotype-dependent activity by demonstration of a high frequency of cytogenetic and pathologic responses in patients with myelodysplastic syndrome and deletion of chromosome 5q. Lenalidomide was approved for the treatment of transfusion-dependent patients with low to intermediate risk myelodysplastic syndrome and chromosome 5q deletion.

SUMMARY

Lenalidomide is an active immunomodulatory agent for the treatment of myelodysplastic syndrome with encouraging erythropoetic and cytogenetic remitting activity that is karyotype dependent.

Transcription mapping of the 5q- syndrome critical region: cloning of two novel genes and sequencing, expression, and mapping of a further six novel cDNAs

The 5q- syndrome is a myelodysplastic syndrome with the 5q deletion ¿del(5q) as the sole karyotypic abnormality. We are using the expressed sequence tag (EST) resource as our primary approach to identifying novel candidate genes for the 5q- syndrome. Seventeen ESTs were identified from the Human Gene Map at the National Center for Biotechnology Information that had no significant homology to any known genes and were assigned between DNA markers D5S413 and D5S487, flanking the critical region of the 5q- syndrome at 5q31-q32. Eleven of the 17 cDNAs from which the ESTs were derived (65%) were shown to map to the critical region of the 5q- syndrome by gene dosage analysis and were then sublocalized by PCR screening to a YAC contig encompassing the critical region. Eight of the 11 cDNA clones, upon full sequencing, had no significant homology to any known genes. Each of the 8 cDNA clones was shown to be expressed in human bone marrow. The complete coding sequence was obtained for 2 of the novel genes, termed C5orf3 and C5orf4. The 2.6-kb transcript of C5orf3 encodes a putative 505-amino-acid protein and contains an ATP/GTP-binding site motif A (P loop), suggesting that this novel gene encodes an ATP- or a GTP-binding protein. The novel gene C5orf4 has a transcript of 3.1 kb, encoding a putative 144-amino-acid protein. We describe the cloning of 2 novel human genes and the sequencing, expression patterns, and mapping to the critical region of the 5q- syndrome of a further 6 novel cDNA clones. Genomic localization and expression patterns would suggest that the 8 novel cDNAs described in this report represent potential candidate genes for the 5q- syndrome.

Circadian rhythm of granulocyte-macrophage colony-stimulating factor in normal subjects and neutropenic hospitalised patients

BACKGROUND

Granulocyte-macrophage colony-stimulating factor (GM-CSF), one of the haemopoietic growth factors, has rarely been detected in human serum. It has, therefore, been suggested that a paracrine model can explain its behaviour where the substance is produced and acts locally. An alternative explanation might be due to blood sampling time with GM-CSF concentrations undetectable at the nadir of secretion.

HYPOTHESIS

We hypothesised that endogenous production of GM-CSF in humans is subject to diurnal rhythm.

METHODS

Blood samples were obtained from 17 healthy individuals and 17 neutropenic hospitalised patients with haematological malignancies on myelosuppressive therapy at 6, 12, 18 and 24 hours. In the neutropenic patients, samples were collected at the nadir of the neutrophil count (ANC < 0.2 x 109/L). Serum was assayed for GM-CSF levels using an enzyme-linked immunosorbent assay method.

RESULTS

There were significant differences in the mean levels of GM-CSF within the two groups (P < 0.001). In normal subjects, peak GM-CSF levels were reached at six hours (mean = 10.1 pg/ml). Peak levels were reached in hospitalised neutropenic patients at 18 hours (mean = 13.7 pg/ml). The difference between the peak GM-CSF levels in the two groups was not significant (P = 0.11). On factorial design analysis, there was a significant interaction between the time of blood collection and the subject groups (P < 0.001).

CONCLUSIONS

Our data are consistent with a diurnal secretion pattern for GM-CSF in both normal and neutropenic patients. As this finding might have practical implications, including timing of administration of GM-CSF in neutropenic patients, further studies are suggested.

Molecular features of primary MDS with cytogenetic changes

Cytogenetic changes in primary myelodysplastic syndromes (MDS) have been extremely useful to identify clonality and to define specific clinico-pathological entities. More recently, with the development of DNA technology, a bulk of new information has been added to classical cytogenetics. Genes corresponding to chromosomal breakpoints implicated in reciprocal translocations have been cloned. Search for the minimal lost region has been the aim of the so-called deletion mapping approach to pick up the hypothetical suppressor gene(s) critical for typical deletions of MDS. Correlation has been found between gene mutations, deletions, expression, and clinical-hematological or cytogenetic features of MDS. Integration of fluorescence in situ hybridization at DNA level and of immunophenotyping at cellular level is an elegant tool to investigate clonal affiliation in MDS with distinct genetic changes.

12p rearrangement and DNA amplification mapped by comparative genomic hybridization in a patient with secondary myeloid leukemia

Rearrangements of the short arm of chromosome 12 (12p) are a common finding in hematologic malignancies. There has recently been considerable interest in chromosome 12 abnormalities in view of the mapping of the TEL gene to 12p13 and frequent 12p interstitial deletions. Overrepresentation of 12p sequences is, on the other hand, a consistent finding in testicular germ cell tumor (TGCT), and the 12p11.2-p12.1 subregion has been found to be specifically involved. We have studied a secondary leukemic patient whose cells contained 12p rearrangements with a view to clarifying the underlying molecular events. Fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH) have revealed the presence of 12p11 breakpoints on both 12 homologs as well as amplification of 12p11-p12-derived sequences. Six YACs and a cosmid probe have been used in an attempt to map the amplification unit on 12p. The two YACs contigs WC-1468 and WC-985 were not amplified, and our results suggested a small amplicon localized in the 12p11.2-p12 subregion. We speculate that this region harbors gene(s) which are critical in tumor formation and could be involved in both TGCT and our patient. Whether the same gene(s) are involved in both amplification and translocation is unknown.

Novel genes mapping to the critical region of the 5q- syndrome

The 5q- syndrome is a myelodysplastic syndrome with specific hematological features and a good prognosis. Using molecular mapping techniques, we have previously defined the critical region of gene loss of the 5q- chromosome in the 5q- syndrome as the approximately 5-Mb region at 5q31-q33 flanked by the genes for FGF1 and IL12B. This region is completely represented by a series of overlapping YACs, and we are currently generating a transcription map with the aim of identifying the tumor-suppressor gene associated with the development of the 5q- syndrome. In this study two techniques have been used: first, the screening of full-length cDNA libraries with radiolabeled YACs and second, the mapping of chromosome 5-specific expressed sequence tags (ESTs) to a YAC contig. A 1-Mb YAC contig encompassing the CSF1R gene has been used to screen a fetal brain cDNA library, and this has resulted in the identification of two genes comprising one known gene previously localized to the region (ADRB2) and one known gene previously unlocalized. Six of 135 chromosome 5-specific ESTs were localized by PCR screening to the YAC contig mapping to the critical region of the 5q- syndrome. IMAGE cDNA clones for each of the six ESTs have been obtained. These seven (excluding ADRB2) newly assigned cDNA clones were subjected to further analysis. The expression patterns of each of the cDNA clones have been established in a range of human tissues, including bone marrow. Six of seven cDNAs are expressed in human bone marrow. Six of seven cDNAs have no known homology to any deposited human sequences, and one (C29) is dihydropyrimidinase-related protein-3, a member of a novel gene family. Genomic localization and expression patterns would suggest that these newly assigned cDNAs represent potential candidate genes for the 5q- syndrome.

A contiguous high-resolution radiation hybrid map of 44 loci from the distal portion of the long arm of human chromosome 5

A contiguous high-resolution map of 44 loci from a 35-Mb portion of the distal region of the long arm of human chromosome 5, q21-q35, was produced using radiation hybrid (RH) mapping in conjunction with a natural deletion mapping panel. The map includes 30 genes, four sequence-tagged site (STS) loci, and 10 DNA markers. Newly mapped markers fill two gap regions that were present in previous maps, between markers FER-IL4 and IL3-IL9. Identifying the position of genes on the physical map aids in positional cloning efforts and contributes to our understanding of the overall organization of the human genome.

Chromosomal assignment of seven genes on canine chromosomes by fluorescence in situ hybridization

Our group has developed more than 600 DNA markers to build a map of the canine genome. Of these markers, 125 correspond to genes (anchor loci). Here we report the first six autosomal genes assigned to canine chromosomes by fluorescence in situ hybridization (FISH), using cosmid DNA: adenine phosphoribosyl transferase on Chromosome (Chr) 3; creatine kinase muscle type on Chr 4; pyruvate kinase liver and red blood cell type on Chr 2; and colony-stimulating factor-1 receptor, glucose transporter protein-2, and tumor protein p53 on Chr 5. These assignments are based on the karyotype proposed by Stone and associates (Genome 34, 407, 1991) using high-resolution techniques. In addition, we have assigned the Menkes gene to the X Chr of the dog.

Cytogenetic findings in 179 patients with myelodysplastic syndromes

Cytogenetic analyses were performed on 266 bone marrow and peripheral blood samples from 179 patients with myelodysplastic syndromes (MDS). According to the FAB classification, 42 patients presented with RA, 18 with RARS, 37 with RAEB, 22 with CMML, and 29 with RAEB-T. Nine patients showed a secondary MDS (S MDS). FAB classification was not available for 22 patients. Clonal karyotype anomalies were found in 92 patients (51.4%). Complex chromosome abnormalities occurred in 17 (18.5%) of them. An evolution of the karyotype was detected in 16 cases (17.4%). Cytogenetically independent cells or cell clones were found in eight patients. Nonclonal chromosome abnormalities were uncovered in 29 (16.2%) of the 179 MDS patients. Consecutive studies were performed in 48 patients and revealed a good correlation of initial karyotype and clinical course. The most frequent single anomalies were 5q- in 29 (31.5%), -7 in 22 (23.9%), trisomy 1q in 14 (15.2%), and +8 in 13 (14.1%) of 92 patients respectively. Our cytogenetic findings are presented in detail and discussed in relation to patients' age, morphological classification, clinical course, and prognostic impact. The contribution of cytogenetic findings to the delineation of multistep pathogenesis of MDS with special emphasis to karyotype instability is demonstrated.

Chromosomal deletions in myelodysplasia

There are two major classes of genes implicated in human tumorigenesis, the oncogenes and the tumour suppressor genes. In haematological malignancies most emphasis has been placed upon the recurring translocations in which the juxtaposition of two gene sequences has resulted in the activation of an oncogene. Chromosomal loss rather than translocation is the most frequent karyotypic abnormality in the myelodysplastic syndromes, a heterogeneous group of clonal malignant blood disorders characterised by dyshaematopoiesis and/or impaired maturation of haemopoietic cells with frequent evolution to acute leukaemia. Recent attention has focused on the loss of genetic material as a result of chromosomal monosomy or deletion in the myelodysplastic syndromes. The most frequently reported deletions in these myeloid syndromes are of chromosomes 5, 20 and 7. Deletions of chromosomes 11, 12, and 13, although more rarely observed, are also characteristics of the myelodysplastic syndromes. It is probable that the deleted chromosomal bands give the location for as yet unidentified myeloid specific tumour suppressor loci and there is considerable interest in the cloning of these genes. This review discusses the three most frequently observed deletions in MDS; 7q deletion, 5q deletion and 20q deletion taking into account recent evidence on the respective critical regions of gene loss and the role of candidate genes.

Expression and genomic configuration of GM-CSF, IL-3, M-CSF receptor (C-FMS), early growth response gene-1 (EGR-1) and M-CSF genes in primary myelodysplastic syndromes

Peripheral blood mononuclear cells from seventeen patients with primary myelodysplastic syndromes (MDS) in advanced stage were enriched for blasts and tested for (1) karyotype, (2) genomic configuration and (3) expression of IL-3, GM-CSF, FMS and EGR-1 genes which are all located on the long arm of chromosome 5. The expression of the M-CSF gene, that has been recently reassigned to the short arm of chromosome 1 (lp), was also investigated. Aims of the study were to (1) assess the potential role of the expression of these genes in the maintenance and expansion of the neoplastic clones and (2) search for constitutional losses or rearrangements of one allele followed by a deletion of the second allele of the same genes in the leukemic cells. The latter issue was investigated by comparing, in 8 cases, constitutive DNA from skin fibroblasts with leukemic DNA. Eleven of the 17 patients had abnormal karyotypes. The M-CSF gene was expressed in 6 cases and the FMS and the EGR-1 genes were expressed in 2 of the latter cases. An autocrine mechanism of growth could be hypothesized only for the 2 patients whose cells expressed both the M-CSF and FMS genes. No germline changes or rearrangements were observed in any of the genes studied. Thus, deregulation of genes encoding for certain hemopoietic growth factors or receptors does not seem to represent a major mechanism of MDS progression.

Molecular heterogeneity at the breakpoints of smaller 20q deletions

Deletions of the long arm of chromosome 20 [del(20q)] are recurring abnormalities in patients with myeloid disorders. Although variable in size, these deletions are usually interstitial. With the object of defining a commonly deleted region for smaller 20q deletions, we used quantitative Southern blot analysis complemented by restriction fragment length polymorphism (RFLP) analysis to determine the copy number at 15 loci spanning 20q. The proximal breakpoints of three such deletions were found to separate HCK and the growth hormone releasing factor (GHRF) locus near the centromeric boundary of band 20q11.2. The distal breakpoints were localized to the vicinity of the D20S22 locus in band q13.1. A candidate tumor suppressor gene, RBL2, and the SRC oncogene were both located within the commonly deleted region. Six loci in terminal region q13.2-q13.3 were conserved on these del(20q) chromosomes, thereby confirming that the deletions were interstitial. Molecular heterogeneity at one and possibly both deletion breakpoints rules out the pathological involvement of loci at these sites. Instead, loss of a tumor suppressor locus from within the commonly deleted region may contribute to deregulated hemopoiesis.

The expression of FMS, KIT and FLT3 in hematopoietic malignancies

Three receptor molecules, belonging to the class III of receptor tyrosine kinases, namely the receptors for colony-stimulating factor 1, CSF1R (product of the FMS proto-oncogene) and Steel factor, SLFR (product of the KIT proto-oncogene), as well as the recently identified FLT3/FLK2 gene product, appear to play distinct roles in normal hematopoietic differentiation. Their potential role in leukemic hematopoiesis has been approached by expression studies in hematopoietic malignancies, especially in acute leukemias of the myeloid and lymphoid lineages. We present here a review of available data, and discuss the possible significance and potential applications of these results.

The biology of stem cell factor, a new hematopoietic growth factor involved in stem cell regulation

Recently, a new hematopoietic growth factor, stem cell factor, the ligand for the c-kit-proto-oncogene, has been cloned. The gene for this factor or for its receptor are deleted in two well known series of mice mutants which display pleiotropic stem cell defects. Therefore, this factor supposedly plays an important role in stem cell biology. This paper reviews some of the elegant genetic work which led to the discovery of the factor and of its receptor, the biological effects that this factor exerts in the hematopoietic system in normal individuals and in patients with Diamond-Blackfan anemia and speculates on some of its potential clinical applications.

Cytogenetic deletion maps of hematologic neoplasms: circumstantial evidence for tumor suppressor loci

Research in oncogenetics has led to the identification of two major classes of tumor-associated genes, oncogenes and tumor suppressor genes. In a wide variety of solid tumor types, mutations of both groups of genes have been implicated in the tumorigenic process. In hematologic neoplasms, on the other hand, most attention has focused on illegitimate activation of oncogenes, e.g., deregulation leading to disturbed transcriptional activity and structural rearrangements resulting in hybrid genes. Whether loss or mutational inactivation of tumor suppressor genes also plays an essential role in the genesis of tumors of the hematopoietic system has received less attention. Because such inactivation can be the result of karyotypically detectable loss of chromosomal material, cytogenetic studies may prove helpful in pinpointing genomic sites that harbor tumor suppressor genes. The present study is based on a total of 12,473 cytogenetically abnormal hematologic neoplasms reported in the literature to date. Among these, we selected the 6,422 cases with sole clonal chromosomal abnormalities in order to include only aberrations of importance in the genesis, rather than in the progression, of these neoplasms. All tumors with monosomies or structural abnormalities resulting in loss of chromosomal material were compiled, and for every such structural aberration, i.e., deletion, unbalanced translocation, isochromosome, and ring chromosome, the chromosome bands lost were ascertained. This cytogenetic deletion mapping revealed that the most commonly lost chromosomes were Y and 7 in acute myeloid leukemia (AML), myelodysplastic syndromes (MDS), and chronic myeloproliferative disorders (MPD); X, Y, 7, 20, and 21 in acute lymphocytic leukemia (ALL); X, Y, and 17 in chronic lymphoproliferative disorders (LPD); and X and Y in non-Hodgkin's lymphoma (NHL). Chromosome segments/bands lost due to unbalanced structural abnormalities in at least 5% of the cases were 5q13-33, 7q22-36, 9q13-31, 11q23-25, 12p12-13, 17p11-13, and 20q11-13 in AML; 5q13-35 and 20q11-13 in MDS; 5q22-23, 7q22, 13q12-22, 17p11-13, and 20q11-13 in MPD; 6q15-27, 9p11-24, 12p12-13, and 19p13 in ALL; 6q16-27, 11q21-25, 13q13-14, and 14q32 in LPD; and 6q21-27, 11q13-25, and 14q24-32 in NHL. Based on these findings, three conclusions can be drawn. First, there is no good correspondence between total and partial monosomies, the only exception being -7 and 7q-, both of which are common in myeloid neoplasms. This indicates different pathogenetic effects of total and partial losses.(ABSTRACT TRUNCATED AT 400 WORDS)

De novo acute leukemia with a sole 5q-: morphological, immunological, and clinical correlations

The 5 q deletion is frequently found in myelodysplastic syndromes and acute non lymphoid leukemia, but this anomaly is usually found in secondary diseases and associated with many other chromosomal aberrations. This report describes four cases of "de novo" acute leukemia with a sole 5q- anomaly. They had no cytological, genetic or clinical characteristics of secondary disorders. It is important to note that of the four patients studied, three had proliferation of immature blast cells. One case was classified as a MO AML and two as "undifferentiated" acute leukemia. Furthermore, these four cases of acute leukemia showed a deletion of the same portion of the long arm of chromosome 5: q22q33. On the same part of this chromosome many hematopoietic growth factor genes have been located, like IL3 and GM-CSF which have early undifferentiated hematopoietic stem cells as a their target.

The colony stimulating factors

Hematopoiesis is a dynamic process, which generate in the range of 10(9) cells/kg each day of erythroid and myeloid cells respectively. In vitro assays that were developed 20 years ago, have been used to define factors that can stimulate growth and differentiation of bone marrow (BM) derived progenitor cells. These growth factors for hematopoiesis were termed Colony Stimulating Factors (CSFs) since the assay system was to induce colonies. With the application of molecular biologic approaches, the genes encoding for these CSFs have been localized and cloned. Production of CSFs and other soluble signal substances (cytokines) as pure proteins have led to important insights into how hematopoiesis is regulated by a complex network made up by interactions between cells and cytokines. The availability of CSFs in clinically useful amounts has also led to clinical trials with new strategies for treating hematopoietic dysfunctions, congenital or acquired. Because others have recently reviewed clinical applications or basic science studies on the colony stimulating factors, we will summarize the two with focus on common features between the different CSFs.

Deletion of IRF-1, mapping to chromosome 5q31.1, in human leukemia and preleukemic myelodysplasia

One of the most frequent cytogenetic abnormalities in human leukemia and myelodysplasia is an interstitial deletion within chromosome 5q. A tumor suppressor gene has been hypothesized to lie in 5q31, the smallest commonly deleted region. IRF-1, a gene whose product manifests anti-oncogenic activity, was mapped to 5q31.1. IRF-1 lies between IL-5 and CDC25C and is centromeric to IL-3 and GM-CSF. Among these genes, only IRF-1 was consistently deleted at one or both alleles in 13 cases of leukemia or myelodysplasia with aberrations of 5q31. Inactivating rearrangements of one IRF-1 allele, accompanied by deletion of the second allele, were also identified in one case of acute leukemia. Thus, IRF-1 may be a critically deleted gene in human leukemia and myelodysplasia.

Translocation (12;14)(q13;q32) in myelodysplastic syndrome

We report a patient diagnosed with refractory anemia with excess blasts in transformation (RAEB-t) who underwent an evolution to a nonlymphocytic acute leukemia (ANLL-M5a). Initial cytogenetic study showed a diploid karyotype; however, when ANLL-M5a was diagnosed, the bone marrow (BM) cells showed a t(12;14)(q13;q32), which to our knowledge has not been described previously in a myelodysplastic syndrome (MDS).

Modulation of cytotoxicity and differentiation-inducing potential of arabinofuranosylcytosine in myeloid leukemia cells by hematopoietic cytokines

Hematopoietic growth factors may be useful in improving the clinical effectiveness of arabinofuranosylcytosine (ara-C). In vitro studies have indicated that interleukin 3(IL-3) and, to a lesser extent, granulocyte-macrophage colony-stimulating factor (GM-CSF), but not G-CSF or M-CSF, may be capable of specifically augmenting the ability of ara-C to kill leukemic myeloid cells by pharmacological and cytokinetic mechanisms including increase of intracellular ara-CTP/dCTP pool ratios and enhanced ara-C DNA incorporation in leukemic blast cells, decrease of IC 90 of ara-C for leukemic colony-forming cells (CFC) as compared with normal CFC growth, and recruitment of quiescent leukemic cells into the cell cycle. In contrast, the combination of ara-C with M-CSF or with the leukemia inhibitory factor (LIF) appears to be useful in overcoming the block in differentiation of leukemic blast, while the effects of GM-CSF and IL-3 on ara-C-induced differentiation appear limited. The combined treatment of human myeloid leukemia cells by ara-C and LIF is associated with down-regulation of c-myc gene expression, transcriptional activation of jun/fos gene expression, and features of functional differentiation (e.g., the capability to reduce nitroblue tetrazolium, to express lysozyme, or to display differentiation-related surface receptors including C3bi and the c-fms protein). On the basis of these in vitro studies first clinical trials are underway that are examining the efficacy of ara-C combinations with these molecules for the treatment of myeloid disorders.

Expression and function of beta-adrenergic receptors in human hematopoietic cell lines

We investigated the expression and functional characteristics of beta-adrenoceptors in a panel of 10 phenotypically different human hematopoietic cell lines. A binding assay with [125I]iodocyanopindolol as the ligand revealed that cell lines of myelomonocytic or histiocytic derivation (HL-60, ML-2, RC-2A, U-937) expressed high numbers of beta-adrenoceptors. An intermediate density of receptors was found in a non-T, non-B cell leukemia line (Nall-1), whereas T-cell (JM, CCRF-CEM), B-cell (Raji) or erythroleukemic cell lines (K-562, HEL) displayed minimal or undetectable binding of the radioligand. Isoprenaline-stimulated cAMP production by the cells correlated to their extent of beta-adrenoceptor expression. Southern blot hybridization analysis of genomic DNA from the cell lines with a 32P-labelled beta 2-adrenoceptor cDNA probe revealed no evidence for major rearrangement or amplification of the receptor gene. Incubation with isoprenaline in vitro suppressed the proliferation of the receptor-rich RC-2A cells but did not affect the growth rate of the receptor-deficient K-562 cells. Treatment with propranolol slightly enhanced the proliferation of the RC-2A cells but did not markedly alter the growth rate of two other cell lines, regardless of their beta-adrenoceptor status. These findings indicate a regulatory influence by the sympathoadrenergic system on selected cells of the myelomonocytic lineage.

Assignment of genes encoding a unique cytokine (IL12) composed of two unrelated subunits to chromosomes 3 and 5

IL12 (formerly NKSF or CLMF) is a unique cytokine composed of two unrelated disulfide-linked subunits. The larger 40-kDa subunit (p40) is a member of the cytokine receptor family, and the smaller 35-kDa subunit (p35) is related to IL6 and GCSF. The chromosomal localization of these two subunits was determined by PCR analysis of DNA from rodent-human hybrids. More refined mapping was obtained by PCR analysis of hybrids containing translocation chromosomes and for p40, by analysis of radiation hybrids. The subunits map to different chromosomes: p40 (IL12B) to 5q31-q33 and p35 (IL12A) to 3p12-3q13.2.

Chromosome mapping of the owl monkey CSF1R and IL5 genes

We mapped the owl monkey colony-stimulating factor 1 receptor (CSF1R) locus to the proximal region of chromosome 3q of karyotype VI(K-VI) and karyotype V(K-V) and the interleukin 5 (IL5) locus to the mid-region of chromosome 3q(K-VI) and 19q(K-IV) using a combination of Southern hybridization of somatic cells and in situ chromosomal hybridization methodologies. The findings support the proposed evolution of owl monkey chromosome 3(K-VI) from a fusion of two smaller structures, the homologs of chromosomes 6 and 19 (K-IV). The data also indicate genomic conservation of the HSA 5q23-q35 segment in the higher primates.

A molecular genetic linkage map of mouse chromosome 18 reveals extensive linkage conservation with human chromosomes 5 and 18

An interspecific backcross between C57BL/6J and Mus spretus was used to generate a molecular genetic linkage map of mouse chromosome 18 that includes 23 molecular markers and spans approximately 86% of the estimated length of the chromosome. The Apc, Camk2a, D18Fcr1, D18Fcr2, D18Leh1, D18Leh2, Dcc, Emb-rs3, Fgfa, Fim-2/Csfmr, Gnal, Grl-1, Grp, Hk-1rs1, Ii, Kns, Lmnb, Mbp, Mcc, Mtv-38, Palb, Pdgfrb, and Tpl-2 genes were mapped relative to each other in one interspecific backcross. A second interspecific backcross and a centromere-specific DNA satellite probe were used to determine the distance of the most proximal chromosome 18 marker to the centromere. The interspecific map extends the known regions of linkage homology between mouse chromosome 18 and human chromosomes 5 and 18 and identifies a new homology segment with human chromosome 10p. It also provides molecular access to many regions of mouse chromosome 18 for the first time.

Sinus histiocytosis with massive lymphadenopathy

To date, the morphological aspects of sinus histiocytosis with massive lymphadenopathy (SHML) have been fully described. The disease is characterized by an enlargement of lymph nodes in which the sinuses are dilated and infiltrated by histiocytes, often phagocytosing lymphocytes. Even if the prognosis is usually benign and not requiring therapy, several fatal cases have been reported. The etiology is still obscure and the biology is not yet completely clear. Recent immunophenotypical studies suggest that histiocytes may belong to the T-zone associated histiocyte lineage. They may be cytologically homogeneous, but can express different antigenic patterns according to their stage of differentiation. Cytogenetic and molecular aspects of the disease have only been sporadically investigated. In order to better understand the pathogenesis of SHML, which seems to be a disorder lying in between the fields of infections, immunological disease and neoplasia, it is considered very useful to systematically employ a variety of immunophenotypical, cytogenetic and molecular techniques to study the disease, particularly in cases which are clinically atypical or with a more aggressive evolution.

Startle disease, or hyperekplexia: Response to clonazepam and assignment of the gene (STHE) to chromosome 5q by linkage analysis

Familial startle disease (also known as hyperekplexia and congenital "stiff-man" syndrome) is an autosomal dominant disorder characterized by an exaggerated startle reaction of sudden, unexpected auditory or tactile stimuli; affected neonates also have severe and occasionally fatal hypertonia. We recently encountered a large, five-generation family with startle disease, and treated 16 patients (including 1 neonate) with clonazepam; all experienced dramatic and sustained improvement. We performed systematic linkage analysis in this family, and found tight linkage between the disease locus and a polymorphic genetic marker locus (colony-stimulating factor receptor, or CSF1R) that has been physically mapped to chromosome 5q33-q35. The maximum odds ratio favoring linkage over nonlinkage is greater than 10,000,000:1 (lod score, 7.10) at 3% recombination. Several genes encoding neurotransmitter receptor components have been physically mapped to the subtelomeric region of chromosome 5q, and are thus candidates for the startle disease gene. The availability of additional large pedigrees with startle disease should facilitate identification and characterization of the gene for this disorder.

Myelodysplastic syndromes. Pathogenesis, diagnosis and treatment

Our understanding of the biology of leukemia and myelodysplasia is still only partial. The diagnosis of myelodysplasia is often based on quantitative and qualitative findings in the peripheral blood and bone marrow. These findings are often shared by other disorders. There is a need for sensitive and inexpensive laboratory tests to determine clonality and karyotypic abnormalities in this disorder. Future classifications of these syndromes will need to be based on morphologic and biologic markers that are closely linked to disease progression, response to treatment, and survival. Our limited understanding of the pathogenesis of MDS decreases the specificity and effectiveness of our therapeutic interventions. Agents that are minimally toxic such as CRA, danazol, 1,25-dihydroxyvitamin D3, androgens, and pyridoxine are seldom useful. Antileukemic therapy and allogeneic bone marrow transplantation have a major role to play in patients younger than 45 years of age; in older patients these treatment modalities remain controversial because of their toxicity. Hematopoietic growth factors, used alone or in combination, may improve the quality of life and improve survival of patients with MDS. Growth factors may also decrease treatment-related mortality associated with chemotherapy and bone marrow transplantation and render these treatment modalities available for a higher percentage of patients. The development of more specific differentiating agents may permit hematopoietic differentiation while minimizing side effects.

Reassignment of the human macrophage colony stimulating factor gene to chromosome 1p13-21

Macrophage colony stimulating factor (CSF-1) is a member of a family of glycoproteins that are necessary for the normal proliferation and differentiation of myeloid progenitor cells. The human CSF-1 gene has previously been assigned to chromosome 5 using somatic cell hybrids, and further localized to 5q33 by in situ hybridization with a 3H labelled cDNA probe. However, the murine macrophage colony stimulating factor gene (csfm) has been localized to a region on mouse chromosome 3 which was previously shown to be syntenic with the proximal region of 1p and not 5q. Using a human genomic DNA clone that contains the CSF-1 gene, we have localized CSF-1 to chromosome 1p13-21 by fluorescence in situ hybridization. The reassignment of the CSF-1 gene argues against its involvement in myeloid disorders with deletions of the long arm of chromosome 5.

Genes encoding the platelet-derived growth factor (PDGF) receptor and colony-stimulating factor 1 (CSF-1) receptor are physically associated in mice as in humans

The BALB/c mouse DNA was analyzed by field-inversion gel electrophoresis to determine the orientation and distance between the beta-platelet-derived growth factor receptor-encoding gene (Pdgfr) and the colony-stimulating factor 1 receptor-encoding gene (Csfmr). It was found that the 5' portion of the Pdgfr gene was cleaved by the enzyme ClaI into two fragments. The 425-kb fragment hybridized with a 3' Pdgfr and a 5' Csfmr probe. This result shows that the Csfmr gene is 3' relative to the Pdgfr gene, and suggests that the Pdgfr and Csfmr genes are physically linked.

Characterization of the 5q- breakpoint in an acute nonlymphocytic leukemia patient using pulsed-field gel electrophoresis

Multiple genes of hematopoietic importance have been localized to the long arm of chromosome 5 including granulocytemacrophage colony stimulating factor (GM-CSF) and interleukins (IL) 3, 4 and 5 to 5q23-31, colony stimulating factor 1 (CSF1) to 5q33.1 and its receptor (c-fms) to 5q33.3. The genes coding for platelet-derived growth factor receptor (PDGFR) and acidic fibroblast growth factor (FGFA) have been localized to 5q31-32 and 5q31.3-33.2, respectively. These genes fall in the region of chromosome 5 which is deleted in the 5q- refractory anemia syndrome (5q-RA) and acute nonlymphocytic leukemia (ANLL). We have characterized this region in a 5q- patient with therapy-related ANLL (t-ANLL) by pulsed-field gel electrophoresis and Southern blotting analysis utilizing DNA probes for PDGFR, c-fms, and FGFA. A single 300 kbp M1uI restriction fragment was detected in the patient using a PDGFR probe as compared to a 200 kbp fragment in normal controls. BssHII digestions also showed restriction fragment length difference. Similar data for both M1uI and BssHII digestions were also obtained when c-fms was used as a probe. Southern blotting analysis of EcoRI-digested DNA showed that each of the PDGFR, c-fms, and FGFA alleles were deleted. These results suggested that one chromosome 5 has a large deletion involving PDGFR, c-fms and FGFA, which is consistent with the cytogenetic analysis of the patient. In contrast, the other chromosome 5, which appeared normal cytogenetically, may have a smaller deletion (or alteration) in proximity to but not involving any of these 3 genes.

Clonality of cell populations in refractory anaemia using combined approach of gene loss and X-linked restriction fragment length polymorphism-methylation analyses

We have used X-linked restriction fragment length polymorphism (RFLP)-methylation and gene deletion analyses to investigate the nature of the progenitor cell of origin in the myelodysplastic syndromes (MDS). Gene deletion studies were performed on the granulocyte and T-lymphocyte fractions of six women with refractory anaemia (RA) and either a partial deletion of the long arm of chromosome 5 (5q-) or monosomy 7. All six showed gene loss in the granulocyte but not the T-lymphocyte fractions, indicating monoclonality of the granulocytes but not the T-lymphocytes. In order to further investigate this finding, we subsequently performed X-RFLP-methylation studies using the probe M27 beta, and also a probe for the phosphoglycerate kinase (PGK) gene. These studies have confirmed the monoclonality of the granulocytes and the polyclonality of the T-lymphocytes in these cases. Our findings suggest that in this group of patients with MDS the T-lymphocytes were not involved in the disorder, and furthermore, in the one case where B-lymphocytes were also available, that the progenitor cell of origin was restricted to the myeloid lineage.

Radiation hybrid map of 13 loci on the long arm of chromosome 5

Radiation hybrid mapping was used in conjunction with a natural deletion mapping panel to predict the order of and distance between 13 loci in the distal portion of the long arm of human chromosome 5. A panel of irradiation hybrids containing fragments of 5q was generated from an HPRT+ Chinese hamster-human cell hybrid containing a derivative chromosome 5 [der(5)t(4;5)(5qter----5p15.1::4p15.1----4pter)] as its only human DNA. One hundred nine radiation hybrids containing human DNA were screened with polymerase chain reaction primer sets representing nine genes encoding growth factors, growth factor receptors, or hormone receptors (IL3, IL4, IL5, CSF1R, FGFA, ADRB2, GRL, GABRA1, and DRD1) as well as four other loci (FER, SPARC, RPS14, and CD14) to generate a radiation hybrid map of the area 5q21-q35. A physical map predicting the order of and distance between the 13 loci was constructed based on segregation of the 13 loci in hybrid clones. The radiation hybrid panel will be useful as a mapping tool for determining the location and order of other genes and polymorphic loci in this region as well as for generating new DNA probes from specific regions.

Mutation of the KIT (mast/stem cell growth factor receptor) protooncogene in human piebaldism

Piebaldism is an autosomal dominant genetic disorder characterized by cogenital patches of skin and hair from which melanocytes are completely absent. A similar disorder of mouse, dominant white spotting (W), results from mutations of the c-Kit protooncogene, which encodes and receptor for mast/stem cell growth factor. We identified a KIT gene mutation in a proband with classic autosomal dominant piebaldism. This mutation results in a Gly----Arg substitution at codon 664, within the tyrosine kinase domain. This substitution was not seen in any normal individuals and was completely linked to the piebald phenotype in the proband's family. Piebaldism in this family thus appears to be the human homologue to dominant white spotting (W) of the mouse.

A frequent EcoRI RFLP demonstrated within the human M-CSF receptor gene (CSFIR)

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Loss of both CSF1R (FMS) alleles in patients with myelodysplasia and a chromosome 5 deletion

A high proportion of patients with myelodysplasia show characteristic karyotypic abnormalities in bone marrow cells. The most distinctive of the myelodysplastic syndromes is the 5q- syndrome characterized by refractory anemia, poorly lobulated megakaryocytes, and an interstitial deletion of the long arm of chromosome 5 (5q deletion) as the sole karyotypic abnormality. Recently, several genes encoding hemopoietic growth factors and receptors, comprising the interleukins 3, 4, and 5, macrophage colony-stimulating factor, granulocyte/macrophage-colony-stimulating factor, and the receptor for macrophage-colony-stimulating factor [the CSF1R (formerly FMS) gene product], have been localized to the long arm of chromosome 5, and there has been much speculation that deletion of one or more of these genes may be critical to the pathogenesis of the associated myeloid disorders. One candidate gene is CSF1R, which is required for normal proliferation and differentiation of hemopoietic cells of the myeloid lineage. We have carried out a molecular examination of the CSF1R, both on the 5q- chromosome and on the apparently normal homologous chromosome 5, in 10 patients with myelodysplasia and a 5q deletion. We have found, using restriction fragment length polymorphism analysis and gene dosage experiments, that all 10 patients showed deletion of CSF1R; 6 of 10 were hemizygous and 4 of 10 homozygous for CSF1R loss. The homozygous CSF1R loss has been confirmed in 2 patients by an in situ hybridization technique comparing the signal in affected cells to that in control sex-mismatched cells on the same slides. In those patients considered to have homozygous CSF1R loss by DNA experiments the gene was deleted from the 5q chromosome in all cells and from the apparently normal chromosome 5 in a subset of cells. This loss of one CSF1R allele, together with loss in some cells of the remaining allele on the homologous chromosome 5, in patients with myelodysplasia indicates that this is a region of critical gene loss on 5q. The loss of the hemopoietic growth factor receptor gene CSF1R may be important in the pathogenesis of human myeloid leukemia.

Hematopoietic growth factor receptors

The molecular cloning for most of the hematopoietic growth factor receptors has been achieved over the past few years and revealed that they can by assigned to two discrete receptor families, namely the hematopoietic growth factor superfamily (HRS) and the receptor tyrosine kinase family (RTK). The members of the HRS, including granulocyte-macrophage colony-stimulating factor receptor (GM-CSF-R), interleukin 3 receptor (IL-3-R), granulocyte CSF receptor (G-CSF-R) and erythropoietin receptor (Epo-R), share a common binding domain and the absence of a tyrosine kinase domain in their cytoplasmic portion. In some cases (e.g., GM-CSF-R), the high-affinity receptor structure is obtained through the association of the low-affinity binding chain (alpha chain) with an accessory protein (beta chain). It is conceivable that this protein might also represent the common subunit shared by GM-CSF-R and by IL-3-R when they are co-expressed to form the putative GM-CSF-R/IL-3-R complex. Although tyrosine phosphorylation following ligand receptor activation seems to be a common event in the HRS, its role in the signal transduction mechanisms is unknown. Due to the structural analogies among the members of this family any new insight into one particular receptor member, such as its subunit structure and its signal transduction pathways, will be generalizable to the other family members. The subclass III of the RTK family, including the CSF-1-R and c-kit, is characterized by an additional insert into the kinase domain that recognizes and binds protein substrates. Ligand induced activation of the kinase domain and its signaling potential are mediated by receptor oligomerization which stabilizes interactions between adjacent cytoplasmic domains and leads to activation of kinase function by molecular interaction. Interestingly, the receptors included in this subclass are the products of well known cellular proto-oncogenes. A large variety of structural alteration found in receptor-derived oncogene products may lead to constitutive activation of receptor signals that, consequently, result in the subversion of the mechanisms controlling the cell growth.