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PubMed1999

[The monitoring of BCR-ABL mRNA by reverse transcription PCR in patients undergoing allogeneic bone marrow transplantation for acute lymphoblastic leukemia with a positive Philadelphia chromosome].

BACKGROUND: Allogeneic bone marrow transplantation (BMT) has been performed as one mode of cure-oriented therapy for Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL-Ph' positive). However, the clinical significance of the residual BCR-ABL-positive clones after BMT is still controversial. PATIENTS AND METHODS: The BCR-ABL gene (p210 and p190) was prospectively studied by nested RT-PCR in 8 ALL-Ph' positive patients undergoing BMT. RESULTS: All patients received BMT at the time of clinical remission (CR). However, minimal residual disease (MRD) was detected in 7 of them. MRD detected just before BMT seems to be eradicated by BMT protocol. Four patients remained in CR and did not show BCR-ABL transcripts. Other 4 patients, relapsed, demonstrating MRD, which preceded recurrence by a median time of 6 weeks. Three relapsed patients showed p190 transcript and only one, p210 type. CONCLUSIONS: The RT-PCR assay appears to be a useful test for predicting at high risk of relapse after BMT and may identify patients who might benefit from therapeutic interventions. The finding that the expression of p190 BCR-ABL may carry an especially high risk of relapse suggests a different clinical and biologic behaviour between p190 and p210 BCR-ABL.

Adult↗
PubMed1990

[Clonality and stem cell defects in the molecular pathology of chronic myeloproliferative disorders].

The chronic myeloproliferative disorders (CMD) are characterized by sustained or progressive proliferations of bone marrow cells, affecting one or more lineages in varying combinations. They are classified in 4 subgroups but transitional forms and transformations among the different entities are common. Analysing RFLPs and methylation patterns of X-chromosomal genes we could show, that in each entity granulocytes as well as bone marrow cells are of monoclonal origin. These findings support the view that all forms of CMD have in common that they arise from a multipotent hematopoietic stem cell. CML can be differentiated from all other forms of CMD by the Philadelphia-chromosome which on the molecular level has been revealed as bcr-abl gene junction. We investigated 258 cases of CMD for rearrangement of the bcr gene and found that it selectively occurred in CML. The methods applied can be of diagnostic value in differentiating reactive from neoplastic proliferations by analysis of clonality, and in differentiation of CML from other types of CMD by detection of the bcr-rearrangement.

Bone Marrow↗
PubMedDate not supplied

Oncogenes and cancer: clinical applications.

Oncogenes are aberrant forms of proto-oncogenes, which are normal cellular genes that participate in cell growth and development; proto-oncogenes contribute to tumor formation when mutations or chromosomal translocation cause them to escape normal controls. Anti-oncogenes, also involved in neoplasm development, normally participate in inhibition of cell growth and proliferation; they become tumorigenic when mutations alter their function. Oncogene or anti-oncogene abnormalities have been characterized for a variety of tumors, with resulting clinical applications. In some forms of leukemia, for example, determining the presence or absence of the bcr-abl gene rearrangement has both diagnostic and prognostic value. The best-studied anti-oncogene is that found in retinoblastoma. Molecular techniques can differentiate the hereditary from the nonhereditary form of this disease and, with hereditary retinoblastoma, predict disease likelihood in family members.

Breast Neoplasms↗
PubMed2002

[The effect of multi-unit ribozymes on the growth inhibition and apoptosis induction of CML K562 cells].

OBJECTIVE: To investigate the possibility of multi-unit ribozymes to purge bone marrow of chronic myelocytic leukemia (CML), its in vitro cleavage ability and the reversal effect on CML cell's malignant phenotype. METHODS: As bcr-abl fusion gene plays an important role in CML pathology, three single-unit ribozymes were designed and synthesized in 44 base pairs near the fusion point, two enzyme cleavage sites on bcr gene and one on abl gene. Multi-unit ribozymes' in vitro transcription and retroviral vector through gene recombination were constructed. Then, its in vitro cleavage ability was tested and the retroviral vector was transfected into K562 cell. Through MTT assay, the incorporation rate of (3)H-TdR, RT-PCR, Southern and Northern blot hybridization, flow cytometry, transmission and scanning electron microscopy were used to study the effect of multi-unit ribozymes on CML cell proliferation, cell structure, cell cycle and the induction of apoptosis. RESULTS: Multi-unit ribozymes had in vitro cleavage efficiency of 70.8%. After the transfection of multi-unit ribozymes retroviral vector into K562 cell, cell proliferation and DNA synthesis were greatly reduced with an inhibition rate of about 50% after 96 hours of transfection. Multi-unit ribozymes could cleave K562 cell's RNA with a reduction rate about one 1 000 th of the original. By flow cytometry (FCM), 18.4% cells underwent apoptosis after 72 hours transfection with most of the cells blocked in the G phase. Here, the ratio in S phase was lowered by 41.9%. Under transmission and scanning electron microscope, compaction of nuclear chromation and apoptosis bodies were observed in the transfected cells. CONCLUSION: Multi-unit ribozymes possess high cleavage ability in vitro. The ribozymes, whose retroviral vector being transfected into CML cell, are able to express a lasting ability to cleave the fusion gene, induce apoptosis, reduce cell proliferation, revert the malignant phenotype. It is possible to make use of multi-unit ribozymes to purge CML bone marrow. Therefore, multi-unit ribozymes may very well be valuable in the gene therapy of CML.

Apoptosis↗
PubMed1990

Myeloproliferative disorders. Classification and diagnostic features with special emphasis on chronic myelogenous leukemia and agnogenic myeloid metaplasia.

Leukocytosis, mild anemia, thrombocytosis, and panhyperplasia in the marrow characterize the early stages of most of the CMPD, whereas extramedullary hematopoiesis (such as in the spleen or liver), peripheral cytopenias (anemia, leukopenia, or thrombocytopenia), and myelofibrosis, with or without osteosclerosis, reflect the changes seen in the later stages. Transitions among the different CMPD and termination in acute leukemia or marrow failure also are common. CML often is characterized by leukocytosis and the presence of the entire spectrum of granulocytes (mature and immature) in the blood and marrow, reduced LAP, hypercellularity with prominent granulocytic hyperplasia in the marrow, Ph chromosome, and bcr-abl gene rearrangement. Typical features of AMM include leukoerythroblastosis, teardrop poikilocytosis, anemia, increased or normal LAP, prominent megakaryocytic hyperplasia in the marrow, dyshematopoiesis, and hyperplastic or fibrotic/sclerotic marrow.

Chromosome Aberrations↗
PubMed2004

Characterization of the different BCR-ABL transcripts with a single multiplex RT-PCR.

The diagnosis of chronic myeloid leukemia is based on detection of the Philadelphia (Ph) chromosome or the BCR-ABL gene. The junction present in the transcript may vary according to the reciprocal translocation t(9;22)(q34;11). Identification of the transcript (p190, p210 or p230) does not reveal the type of junction but this information is very important for classification of patients in clinical trials. Most identification kits do not explore p230 transcripts and are unable to determine exotic breakpoints. We have developed a clinical molecular diagnosis assay, able to identify all of the BCR-ABL transcripts and, by single assay, to characterize all of the possible transcript junctions. This technique is based on RT-PCR and PCR-capillary electrophoresis. For each patient sample, we performed RT-PCR with three different BCR primers each coupled to a specific different fluorochrome and a unique reverse ABL primer. Depending on the transcript, only one BCR primer was used for each RT-PCR. After capillary electrophoresis and fluorescence determination, we were able to identify both the transcript and its junction at the same time.

DNA Primers↗
PubMed1989

[Cloning and study of the function of recA-like gene of Yersinia pestis in Escherichia coli cells].

A 2 kb fragment of Yersinia pestis genome cloned in Escherichia coli cells of the strain HB101 contains a gene able to complement the recA-dependent deficiency of E. coli cells in UV-resistance, resistance to alkylating agents, UV- and MNNG-induced mutability. Cellular capability for homologous recombination in crosses with HfrH donor, derepressed synthesis of bacteriocins (colicin E1 and pesticin 1) is also complemented by the fragment in E. coli recA-strains. The obtained data suggest the functional homology of the cloned recA-like gene product with the product of E. coli recA-gene.

Cloning, Molecular↗
PubMed1995

[Granulocyte abnormal chromatin clumping syndrome: report of a new case and review of the literature].

Abnormal chromatin clumping syndrome (ACCS) is a rare granulocyte disease halfway between Ph'-negative chronic myelogenous leukaemia (CML) and the myelodysplastic syndromes. A new case of such syndrome is presented, the patient being a 65 year-old man with anaemia, thrombocytopenia and myelaemic leucocytosis with abnormal condensation of the neutrophils' chromatin. Marked granulocytic hyperplasia was present in the bone marrow with strikingly dysplastic features, along with a decrease of the remaining blood cell lines. Irregular nuclear outlines and heterochromatin clumps separated by euchromatin bands were seen in the more mature granulocytes upon ultrastructural studies. No cytogenetic abnormalities were found in the bone marrow, and no ber-abl gene rearrangement was present in white cells from peripheral blood. The clinical course was marked by persistence of the anaemia and increasing leucocytosis which required 6-mercaptopurine treatment. Acute myeloblastic leukaemia occurred one year later and the patient died shortly after. It was concluded, from this case and others reported in the literature, that, with regard to its clinical course and proliferative character, ACCS is closer to Ph'-negative, bcr-abl negative CML rather than to the myelodysplastic syndromes.

Aged↗
PubMed2003

Expression of BCR/ABL and BCL-2 in myeloid progenitors leads to myeloid leukemias.

Chronic myelogenous leukemia is a myeloproliferative disorder (MPD) that, over time, progresses to acute leukemia. Both processes are closely associated with the t(9;22) chromosomal translocation that creates the BCR/ABL fusion gene in hematopoietic stem cells (HSCs) and their progeny. Chronic myelogenous leukemia is therefore classified as an HSC disorder in which a clone of multipotent HSCs is likely to be malignantly transformed, although direct evidence for malignant t(9;22)+ HSCs is lacking. To test whether HSC malignancy is required, we generated hMRP8p210BCR/ABL transgenic mice in which expression of BCR/ABL is absent in HSCs and targeted exclusively to myeloid progenitors and their myelomonocytic progeny. Four of 13 BCR/ABL transgenic founders developed a chronic MPD, but only one progressed to blast crisis. To address whether additional oncogenic events are required for progression to acute disease, we crossed hMRP8p210BCR/ABL mice to apoptosis-resistant hMRP8BCL-2 mice. Of 18 double-transgenic animals, 9 developed acute myeloid leukemias that were transplantable to wild-type recipients. Taken together, these data indicate that a MPD can arise in mice without expression of BCR/ABL in HSCs and that additional mutations inhibiting programmed cell death may be critical in the transition of this disease to blast-crisis leukemia.

Animals↗
PubMed1990

Plasmid transformation of Streptomyces venezuelae: modified procedures used to introduce the gene(s) for p-aminobenzoate synthase.

Sucrose was unsuitable as an osmotic stabilizer in buffer solutions and media used for transformation of Streptomyces venezuelae ISP5230. Its replacement with NaCl, together with other modifications in the procedure, allowed efficient formation and regeneration of protoplasts but did not support transformation of S. venezuelae ISP5230 by vectors pIJ41 and pIJ941. With pIJ702, transformants with a low plasmid-copy-number and altered growth characteristics were obtained. Both pIJ702 and pIJ941, but not pIJ41, transformed S. venezuelae 13s; when pIJ941 was used, the plasmid in 18 of 20 transformants contained a deletion in the region reported to code for replication and transfer. The modified plasmid transformed S. venezuelae ISP5230 efficiently and was used to introduce a fragment of DNA from the pab locus of the wild-type into a Cml-1 mutant of ISP5230 blocked in chloramphenicol formation. Transformants that overproduced p-aminobenzoic acid were obtained but they remained blocked in chloramphenicol production; thus, the cloned pab fragment did not contain genes able to complement the cml-1 mutation. The results also suggest that the Cml-1 phenotype is not due to a defective reaction common to the biosynthesis of p-aminobenzoic acid and chloramphenicol.

4-Aminobenzoic Acid↗
PubMed1995

Specific antisense oligomer anti Bcr-abl junctions in chronic myeloid leukemia: a cell cycle analysis and CFU-GM study.

Antisense oligonucleotides were used to determine the role of the BCR-ABL gene in the proliferation of chronic myeloid leukaemia (CML) clonogenic cells. Peripheral blood Philadelphia chromosome positive cells were obtained from eight CML patients at diagnosis (chronic phase = 7; accelerated phase = 1). Mononuclear cells were incubated with synthetic antisense 18-mer oligonucleotides complementary to the two different junctions b2a2 or b3a2. The type of junction (b2a2 or b3a2) was previously determined by RT-PCR techniques. Cells incubated for 12 to 14 hours with or without sense oligonucleotides served as controls. After incubation with oligonucleotides, the cell DNA synthesis was analysed by flow cytometry using the BrdUrd/DNA method and the cell plating efficiency in methylcellulose was determined. In six of the seven patients in chronic phase, there was a significant inhibition of CFU-GM production which was only 68.4 +/- 19%; (p < .01) of that found in controls. The S phase index, which depends upon the percentage of S phase cells as well as the fluorescence intensity, was 48 +/- 29% (p < .01) of the control values for the seven patients in chronic phase. Interestingly, for the only CML patient in accelerated phase, antisense oligomers had no inhibitory effect on either the production of CFU-GM or the number of S phase cells. In improving the specificity of oligomers, it might be useful for gene-targeted anti-leukemic therapy and/or bone marrow purging.

Base Sequence↗
PubMed1996

[Gene transfer and radiotherapy].

Recent studies have shown that experimental tumors could be treated more efficiently with ionizing radiation if genetic material was transfered into tumor cells. Several approaches have been reported, and among them, the first one consisted of increasing the apoptotic response to radiation by modulating genes involved in the regulation of the apoptotic pathway. Indeed the modulation of p53 and bcl-2 gene expression has recently been used successfully in several experimental models to increase the apoptotic death after radiation. A second approach consisted of taking advantage of the conditional expression of some genes after exposure to ionizing radiation. Indeed, some genes exhibit a radio-inducible promoter which can be combined to a gene, able to enhance or decrease the biological effect of radiation. The irradiation of such a transgene under the control of a radio-inducible promoter can lead to a second biological effect, concomitant to the irradiation, as reported for the TNF alpha under the control of the EGR (early growth response) promoter. A third approach consisted of enhancing the effect of radiation induced tumor cell death by the expression of a suicide gene in these cells, as suggested recently for the HSV-tk (herpes virus thymidine kinase gene). These preliminary results obtained in experimental models appear to be very promising and might improve the efficacy and specificity of radiation therapy in a not too distant future.

Animals↗
PubMed2002

Location of the BCR/ABL fusion genes on both chromosomes 9q34 in Ph negative chronic myeloid leukemia.

We present two patients with Ph-negative chronic myeloid leukemia (CML) and fusion signal BCR/ABL on both chromosomes 9, located in region 9q34. The first case was a 27 years old man with CML. Molecular studies (RT-PCR) revealed the rearrangement in the major-BCR region and expression of chimeric BCR/ABL mRNA of b3a2 configuration. By classical cytogenetic studies (G-banding) karyotype 46,XY was found in short-term cultivated bone marrow cells and phytohemagglutinin (PHA) stimulated peripheral lymphocytes. FISH studies revealed the BCR/ABL fusion signals on both chromosomes 9 and green BCR signals on both chromosomes 22 in all mitoses studied. Detection of the alleles of ABL1 intragenic STR locus by fluorescence PCR followed by fragmentation analysis in the patient and his parents provided no information about transmission of the ABL gene. Quantitative assessment of BCR/ABL transcript level by RT-PCR showed 60 and 70% BCR/ABL positivity in two peripheral blood samples at 6,5 and 10,5 months after diagnosis, respectively, which does not correspond to the expression from two identical BCR/ABL hybrid genes. Therefore, the possible mechanism of the origin of two BCR/ABL fusion signals present on both chromosomes 9 could not be resolved and remains speculative. The second case was a 53 years old male with diagnosis of chronic phase of CML, with first sign of acceleration one month after diagnosis and death because of sepsis in blastic phase within four months. The cytogenetic findings were identical to those in case No. 1., i.e. karyotype 46, XY by G-banding, two BCR/ABL fusion signals on both chromosomes 9 and RT-PCR molecular studies proved b3a2 breakpoints. It is generally accepted that prognosis of the patients with fused BCR/ABL gene located on chromosome 9 is poor. The presence of two fused genes could be anticipated as two Ph chromosomes in accelerated and blastic phases of the disease. However, in our study, quantitative findings of BCR/ABL transcripts did not corresponded to the expression of two BCR/ABL genes originating from duplication. If this assumption is correct then the expression of both fused genes BCR/ABL was in case No. 1 equally suppressed and total expression reached about the level of one BCR/ABL gene.

Adult↗
PubMed1990

Characterization of the human ABL promoter regions.

Gel retardation and DNAase 1 footprinting experiments have been performed to characterize the promoter sequences of exon 1a and 1b of the human ABL gene. Several Sp1 motifs and CCAAT boxes are found to be protected by nuclear proteins in the 1b promoter but none of the 7 reported Sp1 sites in 1a were found to bind protein. Multiple sets of initiation sites seem to exist in the 1b promoter region which may represent individual initiation sites, distributed over a DNA region of up to 700 bp. Starting with the most distal initiation site, 1a and 1b ABL promoter sequences show a high degree of homology, suggesting that one is derived from the other. However, multiple evolutionary changes in the 1a promoter sequence indicate that type 1a ABL expression may be differently regulated than 1b.

Abelson murine leukemia virus↗
PubMed2005

Selecting and deselecting imatinib-resistant clones: observations made by longitudinal, quantitative monitoring of mutated BCR-ABL.

Resistance to imatinib during the treatment of chronic myeloid leukaemia (CML) is frequently associated with point mutations in the ABL gene encoding the ATP binding region likely to cause disease relapse. Early diagnosis and monitoring of these mutations may be important in order to prevent rapid expansion of resistant clones. We describe a quantitative mutation-specific PCR assay based on the readily available Taqman platform. Selectivity for the mutated target is conferred by mutation-specific primers destabilised by additional mismatches. The assay can be carried out in parallel to standard BCR-ABL quantification and is therefore more quickly compared to standard sequencing procedures. The sensitivity of the assay reaches 0.1%. It also allows for quantitative assessment of mutated clones. By analysing sequential samples of resistant subjects, we show how mutated clones were selected, maintained or deselected depending on the individual treatment setting. The high sensitivity and practical merits of this method makes it a good candidate for prospective molecular surveillance of patients at high risk for imatinib resistance.

Adult↗
PubMed2006

Dosage compensation in mammals: fine-tuning the expression of the X chromosome.

Mammalian females have two X chromosomes and males have only one. This has led to the evolution of special mechanisms of dosage compensation. The inactivation of one X chromosome in females equalizes gene expression between the sexes. This process of X-chromosome inactivation (XCI) is a remarkable example of long-range, monoallelic gene silencing and facultative heterochromatin formation, and the questions surrounding it have fascinated biologists for decades. How does the inactivation of more than a thousand genes on one X chromosome take place while the other X chromosome, present in the same nucleus, remains genetically active? What are the underlying mechanisms that trigger the initial differential treatment of the two X chromosomes? How is this differential treatment maintained once it has been established, and how are some genes able to escape the process? Does the mechanism of X inactivation vary between species and even between lineages? In this review, X inactivation is considered in evolutionary terms, and we discuss recent insights into the epigenetic changes and developmental timing of this process. We also review the discovery and possible implications of a second form of dosage compensation in mammals that deals with the unique, potentially haploinsufficient, status of the X chromosome with respect to autosomal gene expression.

Amino Acid Sequence↗
PubMedDate not supplied

Allele frequencies of +874T-->A single nucleotide polymorphism at the first intron of interferon-gamma gene in a group of Italian centenarians.

Ageing is characterized by a pro-inflammatory status which could contribute to the onset of major age-related diseases such as cardiovascular diseases, neurodegeneration, osteoarthritis and osteoporosis, and diabetes. Thus, it can be hypothesized that genetic variations in pro- or anti-inflammatory cytokines might influence successful ageing and longevity. We have studied the distribution of +874T-->A interferon-gamma (IFN-gamma) polymorphisms in a large number of Italian centenarians to evaluate if the two alleles might be differently represented in people selected for longevity. DNA samples were obtained from 174 Italian centenarians (>99 years old, 142 women and 32 men) and from 248 <60-year-old control subjects (90 women and 158 men) matched for geographical distribution. Polymorphisms at +874 were identified by using amplification refractory mutational system methodology. The +874T allele was found less frequently in centenarian women than in centenarian men or in control women whereas no significant differences were observed in the distribution of the two alleles between male or female controls. Allele frequencies in centenarian men were not found significantly different from male controls. Possession of the +874A allele, known to be associated with low IFN-gamma production, significantly increases the possibility to achieve extended longevity, suggesting that the pro-inflammatory status characteristic of ageing may be detrimental for successful ageing. The datum that the allele was significantly increased in female but not male centenarians seems to strengthen the idea that gender may be a major variable in the biology of the ageing process. However, the present data add another piece of evidence to the complex puzzle of genetic and environmental factors involved in controlling life span expectancy in humans. Thus, studies on cytokine gene polymorphisms may promise to individuate a complex network of trans-interactive genes able to influence the type and strength of responses to environmental stressors and as a final result, thereby conditioning individual life expectancy.

Adult↗
PubMed1998

A comparative analysis of FISH, RT-PCR, and cytogenetics for the diagnosis of bcr-abl-positive leukemias.

Philadelphia (Ph) chromosome-positive leukemias, with the bcr-abl gene translocation, have a dismal prognosis. The identification of Ph-positive patients is vitally important because only aggressive therapeutic approaches, such as allogeneic bone marrow transplantation, may result in long-term disease-free survival. Routine diagnostic methods, such as Southern blot analysis and cytogenetics, may lead to false-negative results. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis is considered the most sensitive tool for the detection of the bcr-abl translocation, and it is widely used alone or in combination with karyotyping or Southern blot analysis to identify Ph-positive cases. In this study, we used fluorescence in situ hybridization (FISH) with BCR and ABL double-color probes for detecting Ph-positive leukemias. The FISH results were compared with the results of cytogenetic and RT-PCR analyses in 75 patients with leukemia or other myeloproliferative syndromes (chronic myeloid leukemia, 30; acute lymphoblastic leukemia, 24; acute myelogenous leukemia, 6; essential (hemorrhagic) thrombocythemia, 12; chronic myelomonocytic leukemia, 2; and polycythemia vera, 1). FISH analysis proved to be simple, extremely reliable and sensitive; bcr-abl fusion detection was successful in the presence of all types of molecular junctions i.e., (b2a2, b3a2, and e1a2). Furthermore, a Ph-positive case that proved fusion negative by RT-PCR was identified as positive by FISH. The sensitivity of RT-PCR and FISH related to Ph-positive cases were 97% and 100%, respectively. Regarding specificity, in 4 (5%) of 75 patients, RT-PCR provided false-positive results. Cross-contamination was identified because a new specimen was harvested and reanalyzed when FISH, cytogenetics, and RT-PCR results were contradictory. We believe FISH is an optimal diagnostic method to detect bcr-abl translocation that can be used alone or to validate the results of RT-PCR analysis.

Bone Marrow↗