Fluorescence in situ hybridization confirmation of 5q deletions in patients with hematological malignancies

Isochromosome 5p and related anomalies: a novel recurrent chromosome abnormality in myeloid disorders

Loss of material from chromosome arm 5q is a common finding in patients with myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML). Fluorescence in situ hybridization with a panel of different types of probes, used as a complement to conventional cytogenetics, revealed that 7 of 148 patients (4.7%) with abnormalities of chromosome 5 had an i(5)(p10), an idic(5)(q11), or a structurally rearranged i(5)(p10). Three patients had MDS and four had AML. Six of the patients were female, and one was male; age at diagnosis ranged from 56 to 85 years. All patients but one had a complex karyotype. Isochromosome of the short arm of chromosome 5 and its related abnormalities such as idic(5)(q11) and structurally rearranged i(5)(p10) are rare but recurrent abnormalities; their identification requires a combination of conventional and molecular cytogenetic techniques. The biological and clinical significance cannot yet be assessed, not only because too few cases have been described but also because these abnormalities are usually part of a complex karyotype.

TGFBI deficiency predisposes mice to spontaneous tumor development

Loss of TGFBI, a secreted protein induced by transforming growth factor-beta, has been implicated in cell proliferation, tumor progression, and angiogenesis by in vitro studies. However, in vivo antitumor functions of TGFBI as well as the underlying molecular mechanism are not well understood. To these aims, we have generated a mouse model with disruption of TGFBI genomic locus. Mice lacking TGFBI show a retarded growth and are prone to spontaneous tumors and 7,12-dimethylbenz(a)anthracene-induced skin tumors. In relation to wild-type (WT) mouse embryonic fibroblasts (MEF), TGFBI(-/-) MEFs display increased frequencies of chromosomal aberration and micronuclei formation and exhibit an enhanced proliferation and early S-phase entry. Cyclin D1 is up-regulated in TGFBI(-/-) MEFs, which correlates with aberrant activation of transcription factor cyclic AMP-responsive element binding protein (CREB) identified by chromatin immunoprecipitation and luciferase reporter assays. TGFBI reconstitution in TGFBI(-/-) cells by either retroviral infection with WT TGFBI gene or supplement with recombinant mouse TGFBI protein in the culture medium leads to the suppression of CREB activation and cyclin D1 expression, and further inhibition of cell proliferation. Cyclin D1 up-regulation was also identified in most of the tumors arising from TGFBI(-/-) mice. Our studies provide the first evidence that TGFBI functions as a tumor suppressor in vivo.

Evaluation of chromosome 5 aberrations in complex karyotypes of patients with myeloid disorders reveals their contribution to dicentric and tricentric chromosomes, resulting in the loss of critical 5q regions

Dicentric chromosomes have often been observed in complex karyotypes in previously reported studies of therapy-related myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). Fluorescence in situ hybridization (FISH) has now made the characterization of these rearrangements much easier. Dicentric and tricentric chromosomes were identified in 21 patients (9 MDS and 12 AML) among the 133 consecutive MDS/AML patients (17%) who had a structural or numerical aberration of chromosome 5 using conventional cytogenetic analysis. One third (7/21) of the patients had received alkylating drugs for a previously diagnosed cancer or chronic myeloproliferative disease. Loss of 5q material was identified in all 21 patients. One copy of the EGR1 (5q31) or the CSF1R (5q33 approximately q34) genes was lost in 20 of the 21 patients. Dicentric and tricentric chromosomes involving chromosome 5 are frequently observed in complex karyotypes among patients with de novo or therapy-related MDS/AML. They lead to deletions of various parts of the long arm of chromosome 5.

Molecular cytogenetic analysis of complex karyotypes with derivative chromosome der(1)t(1;5) found in two patients with myeloid leukemia

Two patients with myeloid hematological malignancies were examined with conventional cytogenetic analysis, and complex chromosomal aberrations were found. Multicolor FISH (mFISH) was used to clarify these rearrangements. A similar translocation between chromosomes 1 and 5 was revealed in both patients. To specify breakpoints, high-resolution multicolor banding (mBAND) for chromosome 1 and chromosome 5 was performed. The breakpoints were resolved as der(1)t(1;5)(p21;p12) in patient 1 and as der(1)t(1;5)(p21;p11) in patient 2. The breakpoint on chromosome 1 was the same in both patients, in the 1p21 region. This region contains the colony stimulating factor 1 gene (CSF1), which may play a role in tumorigenesis of myeloid tissue.

Redefining monosomy 5 by molecular cytogenetics in 23 patients with MDS/AML

Deletion of the long arm of chromosome 5 [del(5q)] or loss of a whole chromosome 5 (-5) is a common finding, arising de novo in 10% of patients with myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML) and in 40% of patients with therapy-related MDS or AML. We investigated by molecular cytogenetics 23 MDS/AML patients for whom conventional cytogenetics detected a monosomy 5. Monosomy 5 was redefined as unbalanced or balanced translocation and ring of chromosome 5. Loss of 5q material was identified in all 23 patients, but one. One copy of EGR1(5q31) or CSF1R(5q33-34) genes was lost in 22 of the 23 patients. Chromosome 5p material was a constant chromosomal component of derivative chromosomes or rings in all patients, but one. Sequential fluorescent in situ hybridization studies with whole chromosome paints and region-specific probes, used as a complement to conventional cytogenetic analysis, allow a better interpretation of karyotypes in MDS/AML patients.

T-cell acute lymphoblastic leukemia relapsing as acute myelogenous leukemia

We present the unusual case of a 16-year-old girl with T-cell acute lymphoblastic leukemia (ALL) with an early thymocyte immunophenotype without myeloid markers, who after 13 months of complete hematological remission relapsed as acute myelogenous leukemia (AML) with minimal differentiation and died of her disease. Whether the AML represented a relapse with lineage switch of the original immature T-cell clone or a new secondary malignancy, could not be proven due to the absence of molecular or clonal markers. This report suggests that a subset of CD7+ T-cell leukemias without mature T-cell antigens (CD4-, CD8-) are minimally differentiated and can relapse as AML.

Loss of Betaig-h3 protein is frequent in primary lung carcinoma and related to tumorigenic phenotype in lung cancer cells

Betaig-h3 as a secreted protein induced by transforming growth factor-beta has been suggested to modulate cell adhesion and tumor formation. Although we have previously shown that downregulation of Betaig-h3 gene is involved in the cellular transformation of human bronchial epithelial cells induced by radiation, its regulation in primary human lung cancers is not clearly understood. In this study, Betaig-h3 expression was studied in 130 primary human lung carcinomas by immunohistochemistry. Betaig-h3 protein was absent or reduced by more than two-fold in 45 of 130 primary lung carcinomas relative to normal lung tissues examined. Recovery of Betaig-h3 expression in H522 lung cancer cells lacking endogenous Betaig-h3 protein significantly suppressed their in vitro cellular growth and in vivo tumorigenicity. In addition, parental H522 cancer cells are resistant to the etoposide induced apoptosis compared with normal human bronchial epithelial cells. However, recovery of Betaig-h3 expression in H522 cancer cells results in significantly higher sensitivity to apoptotic induction than parental tumor cells. IGFBP3 is upregulated in Betaigh3-transfected H522 cells that may mediate the apoptotic sensitivity and antitumor function of Betaig-h3 gene. These observations demonstrate that downregulation of Betaig-h3 gene is a frequent event and related to the tumor progression in human lung cancer.

Characterisation of a new splice variant of MASK-BP3(ARF) and MASK human genes, and their expression patterns during haematopoietic cell differentiation

In this study we report the characterisation of a new splice variant, here denominated splice variant 4 (accession number AF258557) of the human Multiple Ankyrin repeats Single KH domain (hMASK) (accession number AF521882) and the hMASK-4E-Binding Protein 3 Alternative Reading Frame (hMASK-BP3(ARF)) (accession number AF521883), containing a number of ANK-repeat motifs. Ankyrin (ANK) repeat-containing proteins carry out a wide variety of biological activities and are involved in processes, such as cell differentiation and transcriptional regulation. The present study reports the computer analysis of these splice variant cDNAs and their broad mRNA expression in different normal human tissues and cancer cell lines. An upregulation of the splice variant mRNAs expression was observed after HL-60 and erythroblast differentiation. The upregulation of splice variant 4 mRNA was considerably higher than those of the other variants, during erythroid differentiation.

Prognostic significance of del(20q) in patients with hematological malignancies

Deletions of the long arm of chromosome 20 represent a common chromosomal abnormality associated with myeloid malignancies, in particular with myeloproliferative disorders (MPD), myelodysplastic syndromes (MDS), and acute myeloid leukemia (AML). Using G-banding cytogenetic techniques, we found clones with del(20q) in 36 patients with hematological malignancies examined in our laboratory during the years 2001-2003: in 23 patients as a sole cytogenetic aberration and in 13 patients together with other chromosomal changes. Fluorescence in situ hybridization (FISH) with a probe specific for the 20q12 region was used in all cases to confirm the presence of the clone with deletion. For patients with additional or complex chromosomal rearrangements, multicolor FISH (M-FISH) analysis was performed. Statistical evaluation of the prognostic impact of sex, age, diagnosis, and karyotype was performed. The survival time correlated with the type of chromosomal aberration; no significant differences in survival were found for sex, age, and diagnosis.

Several chromosomes involved in translocations with chromosome 5 shown with fluorescence in situ hybridization in patients with malignant myeloid disorders

In many patients with myelodysplastic syndromes or acute myeloid leukemia, complex chromosome aberrations can be seen, among which aberrations of chromosome 5 constitute a substantial part. With conventional cytogenetic technique, these aberrations are often identified as deletions or monosomy 5. We analyzed nine patients who, under conventional cytogenetic analysis, showed deletion or monosomy 5. We used fluorescence in situ hybridization with whole-chromosome painting probes to identify the counterpart chromosome and locus-specific identifiers for 5q31 and 5q33 approximately q34. A deletion of 5q was found concomitant with unbalanced translocations. Our results and cases from the literature showed that material from chromosome 5 could be translocated to almost all chromosomes. All patients but one had short survival; this one patient had a preserved 5q31 and 5q33 approximately q34 but a deletion of the q-arm more centromeric than these bands. In eight of the nine patients, further 14 translocations were revealed, not involving chromosome 5.

Systematic screening at diagnosis of −5/del(5)(q31), −7, or chromosome 8 aneuploidy by interphase fluorescence in situ hybridization in 110 acute myelocytic leukemia and high-risk myelodysplastic syndrome patients: concordances and discrepancies with conventional cytogenetics

To assess the contribution of interphase fluorescence in situ hybridization (I-FISH) toward the detection of recurring unbalanced chromosomal anomalies at diagnosis, a systematic screening of -5/del(5)(q31), -7, and chromosome 8 aneuploidy was performed on 110 patients with acute myelocytic leukemia or high-risk myelodysplastic syndrome. We searched for monosomy 5/del(5q) by one-color I-FISH with a probe specific for the 5q31 region and for -7/8 by dual-color I-FISH with centromeric probes for chromosomes 7 and 8. Discrepancies between conventional cytogenetics (CC) and I-FISH were observed in 8 of the 110 patients (7.3%). For -5/del(5)(q31), a discordance was observed in two patients with complex abnormalities involving chromosome 5. Whereas no discordance was observed for -7, I-FISH detected a trisomy 7 unnoticed by CC in two cases. In six patients, I-FISH revealed a chromosome 8 aneuploidy not detected by CC. Our results illustrate that, when using this specific set of probes, I-FISH is of special interest for the detection of minor clones with chromosome 8 aneuploidy, breakpoint assessment, and sequence identification (markers). Also, to avoid misinterpretations, I-FISH should not be used alone at disease presentation, particularly in cases complex changes that have clearly established prognostic significance.

A prognostic impact of separation of refractory cytopenia with multilineage dysplasia and 5q- syndrome from refractory anemia in primary myelodysplastic syndrome

A prognostic impact of WHO classification of myelodysplastic syndrome (MDS) was studied in a group of 103 primary MDS patients with refractory anemia (RA) according to French-American-British (FAB) classification. Median survival of 37 patients with RA according to WHO criteria of 85.2 months was significantly different from that in both 37 patients with refractory cytopenia with multilineage dysplasia (RCMD) (47.0 months, P=0.002) and 29 patients with 5q- abnormality diagnosed by routine chromosome banding (36.2 months, P=0.0002). A more detailed karyotype analysis with fluorescent in situ hybridization (FISH) techniques confirmed 5q deletion as a sole cytogenetic abnormality in only 12 out of 29 patients, in 4 patients 5q- was associated with complex abnormalities involving 5q region, 13 patients had 5q deletion combined with further karyotype abberations outside 5q. No difference in median survival and estimated 3 years survival was observed between RA patients, patients with 5q- syndrome according to WHO morphology criteria and patients with 5q- as a single abnormality confirmed by FISH in contrast to patients with either additional 5q abberations or further karyotype changes not involving 5q. The same difference was also observed in time to 25% of patients evolving to acute myeloid leukemia (AML). Our study confirmed usefulness of separation of RCMD from RA. RCMD represents a poor prognostic subgroup of MDS clearly distinct from pure RA mainly due to short survival connected with progressive bone marrow failure and increased risk of leukemic transformation. We also suggest to define 5q- syndrome as primary MDS of FAB type RA with 5q deletion as a sole cytogenetic abnormality confirmed by FISH analysis. This definition enabled us to discriminate 5q- patients with favorable prognosis similar as in RA from those with poor outcome associated with 5q- combined with complex abnormalities involving either 5q or regions outside 5q.

Tumor suppressor function of Betaig-h3 gene in radiation carcinogenesis

Interaction between cell and extracellular matrix (ECM) plays a crucial role in tumor invasiveness and metastasis. Using an immortalized human bronchial epithelial (BEP2D) cell model, we showed previously that expression of a list of genes including Betaig-h3 (induced by transforming growth factor-beta), DCC (deleted in colorectal cancer), p21(cipl), c-fos, Heat shock protein (HSP27) and cytokeratin 14 were differentially expressed in several independently generated, radiation-induced tumor cell lines (TL1-TL5) relative to parental BEP2D cells. Our previous data further demonstrated that loss of tumor suppressor gene(s) as a likely mechanism of radiation carcinogenesis. In the present study, we chose Betaig-h3 and DCC that were downregulated in tumorigenic cells for further study. Restored expression of Betaig-h3 gene, not DCC gene, by transfecting cDNA into tumor cells resulted in a significant reduction in tumor growth. While integrin receptor alpha 5 beta 1 was overexpressed in tumor cells, its expression was corrected to the level found in control BEP2D cells after Betaig-h3 transfection. These data suggest that Betaig-h3 gene is involved in tumor progression by regulating integrin alpha 5 beta 1 receptor. Furthermore, exogenous TGF- beta 1 induced expression of Betaig-h3 gene and inhibited the growth of both control and tumorigenic BEP2D cells. Therefore, downregulation of Betaig-h3 gene may results from the decreased expression of upstream mediators such as TGF-beta. The findings provide strong evidence that the Betaig-h3 gene has tumor suppressor function in radiation-induced tumorigenic human bronchial epithelial cells and suggest a potential target for interventional therapy.

Downregulation of Betaig-h3 gene is causally linked to tumorigenic phenotype in asbestos treated immortalized human bronchial epithelial cells

Although Betaig-h3 gene has been suggested to modulate cell adhesion and tumor formation, its physiological functions are not well understood. Using human papillomavirus immortalized human bronchial epithelial (BEP2D) cells, we found that Betaig-h3 expression was markedly decreased in asbestos-induced tumorigenic cells. Fusion of tumorigenic and control BEP2D cells resulted in the recovery of Betaig-h3 gene expression to control level and the loss of tumorigenic phenotype. Furthermore, ectopic expression of Betaig-h3 gene in asbestos-induced tumorigenic cells inhibited cell growth in vitro, anchorage independent phenotype, as well as tumorigenicity in nude mice. Betaig-h3 gene is ubiquitously expressed in various normal human tissues, with the exception of the brain, where there is little or no expression. In contrast, there was a decrease or absence in expression of the Betaig-h3 gene in 14 human tumor cell lines of diverse histological types examined, when compared with normal human cells or tissues. The result strongly suggests that loss of Betaig-h3 expression is a frequent event in human cancer and causally related to acquisition of tumorigenic phenotype in asbestos-treated BEP2D cells.

Overexpression of Betaig-h3 gene downregulates integrin alpha5beta1 and suppresses tumorigenicity in radiation-induced tumorigenic human bronchial epithelial cells

Interaction between cell and extracellular matrix plays a crucial role in tumour invasion and metastasis. Using an immortalised human bronchial epithelial (BEP2D) cell model, the study here shows that expression of Betaig-h3 gene, which encodes a secreted adhesion molecule induced by transforming growth factor-beta, is markedly decreased in several independently generated, radiation-induced tumour cell lines (TL1-TL5) relative to parental BEP2D cells. Transfection of Betaig-h3 gene into tumour cells resulted in a significant reduction in tumour growth. While integrin receptor alpha5beta1 was overexpressed in tumour cells, its expression was corrected to the level found in control BEP2D cells after Betaig-h3 transfection. These data suggest that Betaig-h3 gene is involved in tumour progression by regulating integrin receptor alpha5beta1. The findings provide strong evidence that the Betaig-h3 gene has tumour suppressor function in human BEP2D cell model and suggest a potential target for interventional therapy.