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PubMed1995

Characterization of genomic BCR-ABL breakpoints in chronic myeloid leukaemia by PCR.

In order to understand better the mechanism of translocation between the BCR and ABL genes in CML, we have exploited a 'bubble PCR' technique to clone genomic breakpoints. BCR-ABL junction fragments were successfully amplified and sequenced in 14/32 (43%) patients tested. Breakpoints were dispersed throughout the major breakpoint cluster region without any clustering or hot spots. In three cases Alu sequences were found at or near the breakpoint on the ABL side of the translocation but no other obvious sequence homologies were found either in BCR or ABL. The translocation event was characterized further in three other patients by amplifying the reciprocal ABL-BCR junction on the 9q+ chromosome and also normal ABL around breakpoints. In two of these patients a few nucleotides of BCR and ABL were either duplicated or deleted on translocation, suggesting that staggered cuts had been made in the DNA strand prior to recombination. In the third patient 50 bp of ABL was deleted and 159 bp of M-BCR including exon b3 was duplicated, indicating either that the single-stranded cuts may span a larger distance than previously thought or that another mechanism, perhaps involving gene conversion, may be involved in this instance.

Base Sequence↗
PubMed2006

Identification of transcriptional targets associated with the expression of p210 Bcr-Abl.

OBJECTIVES: Chronic myeloid leukaemia is caused by the expression of the p210 Bcr-Abl fusion protein which results from the Philadelphia translocation, t(9;22). This oncogene has been the focus of extensive research. However, the molecular mechanisms responsible for the haematological malignancy are not fully understood. The main objective of the current study was to identify novel transcriptional targets of Bcr-Abl. METHODS: In order to achieve this, microarrays were employed in order to conduct a genome-wide expression analysis comparing 32D cells with a transfected clone expressing high levels of p210 Bcr-Abl. Quantitative RT-PCR was employed in order to confirm the observed increase/decrease in expression for a number of the deregulated genes. RESULTS AND CONCLUSIONS: This comparison identified 138 genes of known function showing altered expression in response to Bcr-Abl-mediated signalling. Among the genes found to be upregulated in response to p210 Bcr-Abl were aldolase 1A and phosphofructokinase, both of which encode key enzymes in the glycolytic pathway. As a consequence of this, we demonstrate that the rate of glycolysis is significantly increased in Bcr-Abl expressing cells in a PI3K-dependent manner. Our results also indicate altered expression of genes involved in cell proliferation, cell adhesion and cell signalling.

Animals↗
PubMed2004

Imatinib mesylate resistance through BCR-ABL independence in chronic myelogenous leukemia.

Imatinib mesylate (IM) binds to the BCR-ABL protein, inhibiting its kinase activity and effectively controlling diseases driven by this kinase. IM resistance has been associated with kinase mutations or increased BCR-ABL expression. However, disease progression may be mediated by other mechanisms that render tumor cells independent of BCR-ABL. To demonstrate this potential, IM-resistant cells were found in chronic myelogenous leukemia patients with continuous BCR-ABL gene expression but undetectable BCR-ABL protein expression. These cells were unresponsive to IM and acquired BCR-ABL-independent signaling characteristics. IM resistance in some patients may be mediated through loss of kinase target dependence.

Antineoplastic Agents↗
PubMed2006

BCR-ABL is not an immunodominant antigen in chronic myelogenous leukemia.

In the present study, we analyzed the involvement of the BCR-ABL protein in the induction of antigen-specific CTL in order to develop an immunotherapeutic approach in patients with chronic myelogenous leukemia (CML). To accomplish this, we generated dendritic cells (DC) in vitro and electroporated them with various sources of RNA harboring the chimeric bcr-abl transcript. These genetically engineered DCs were used as antigen-presenting cells for the induction of CTLs. By applying this approach, we found that the CTLs induced by DCs transfected with RNA extracted from bcr-abl-positive K-562 cells or CML blasts lysed DCs transfected with the corresponding RNA, but failed to recognize epitopes derived from the chimeric BCR-ABL fusion protein in (51)Cr-release assays. In contrast, they were able to lyse autologous DCs electroporated with RNA isolated from patients with acute myeloid leukemia, indicating that antigens shared among these malignant cells are involved and recognized by these CTLs. In patients with CML in complete cytogenetic remission during IFN-alpha treatment, we detected some reactivity of CD8(+) T cells against BCR-ABL in IFN-gamma ELISPOT assays, which was weaker as compared with proteinase 3 (PR3)- or prame-directed responses, suggesting that the BCR-ABL protein is less immunogenic as compared with other CML-derived antigens.

CD4-Positive T-Lymphocytes↗
PubMed2004

Imatinib (STI571)-mediated changes in glucose metabolism in human leukemia BCR-ABL-positive cells.

The therapeutic efficacy of imatinib mesylate (Gleevec) is based on its specific inhibition of the BCR-ABL oncogene protein, a widely expressed tyrosine kinase in chronic myelogenous leukemia (CML) cells. The goal of this study was to evaluate glucose metabolism in BCR-ABL-positive cells that are sensitive to imatinib exposure. Two human BCR-ABL-positive cell lines (CML-T1 and K562) and one BCR-ABL-negative cell line (HC-1) were incubated with different imatinib concentrations for 96 hours. Magnetic resonance spectroscopy on cell acid extracts was performed to evaluate [1-13C]glucose metabolism, energy state, and changes in endogenous metabolites after incubation with imatinib. Imatinib induced a concentration-dependent inhibition of cell proliferation in CML-T1 (IC50, 0.69 +/- 0.06 micromol/L) and K562 cells (IC50, 0.47 +/- 0.04 micromol/L), but not in HC-1 cells. There were no metabolic changes in imatinib-treated HC-1 cells. In BCR-ABL-positive cells, the relevant therapeutic concentrations of imatinib (0.1-1.0 micromol/L) decreased glucose uptake from the media by suppressing glycolytic cell activity (C3-lactate at 0.25 mmol/L, 65% for K562 and 77% for CML-T1 versus control). Additionally, the activity of the mitochondrial Krebs cycle was increased (C4-glutamate at 0.25 micromol/L, 147% for K562 and 170% for CML-T1). The improvement in mitochondrial glucose metabolism resulted in an increased energy state (nucleoside triphosphate/nucleoside diphosphate at 0.25 micromol/L, 130% for K562 and 125% for CML-T1). Apoptosis was observed at higher concentrations. Unlike standard chemotherapeutics, imatinib, without cytocidal activity, reverses the Warburg effect in BCR-ABL-positive cells by switching from glycolysis to mitochondrial glucose metabolism, resulting in decreased glucose uptake and higher energy state.

Antineoplastic Agents↗
PubMed2006

Curcumin affects components of the chromosomal passenger complex and induces mitotic catastrophe in apoptosis-resistant Bcr-Abl-expressing cells.

The Bcr-Abl oncoprotein plays a major role in the development and progression of chronic myeloid leukemia and is a determinant of chemotherapy resistance occurring during the blast crisis phase of the disease. The aim of this article was to investigate the possibility of combating the resistance to apoptosis caused by Bcr-Abl by inducing an alternative cell death process. As a model of chronic myeloid leukemia, we employed Bcr-Abl-transfected mouse progenitor 32D cells with low and high Bcr-Abl expression levels corresponding to drug-sensitive and drug-resistant cells, respectively. The drug curcumin (diferuloylmethane), a known potent inducer of cell death in many cancer cells, was investigated for efficacy with Bcr-Abl-expressing cells. Curcumin strongly inhibited cell proliferation and affected cell viability by inducing apoptotic symptoms in all tested cells; however, apoptosis was a relatively late event. G(2)-M cell cycle arrest, together with increased mitotic index and cellular and nuclear morphology resembling those described for mitotic catastrophe, was observed and preceded caspase-3 activation and DNA fragmentation. Mitosis-arrested cells displayed abnormal chromatin organization, multipolar chromosome segregation, aberrant cytokinesis, and multinucleated cells-morphologic changes typical of mitotic catastrophe. We found that the mitotic cell death symptoms correlated with attenuated expression of survivin, a member of the chromosomal passenger complex, and mislocalization of Aurora B, the partner of survivin in the chromosomal passenger complex. Inhibition of survivin expression with small interfering RNA exhibited similar mitotic disturbances, thus implicating survivin as a major, albeit not the only, target for curcumin action. This study shows that curcumin can overcome the broad resistance to cell death caused by expression of Bcr-Abl and suggests that curcumin may be a promising agent for new combination regimens for drug-resistant chronic myeloid leukemia.

Animals↗
PubMed2004

Activation of the PI3K/mTOR pathway by BCR-ABL contributes to increased production of reactive oxygen species.

BCR-ABL oncoprotein-expressing cells are associated with a relative increase of intracellular reactive oxygen species (ROS), which is thought to play a role in transformation. Elevated ROS levels in BCR-ABL-transformed cells were found to be blocked by the mitochondrial complex I inhibitor rotenone as well as the glucose transport inhibitor phloretin, suggesting that the source of increased ROS might be related to increased glucose metabolism. The glucose analog 2-deoxyglucose (2-DOG) reduced ROS to levels found in non-BCR-ABL-transformed cells and inhibited cell growth alone or in cooperation with imatinib mesylate (Gleevec). A mutant of BCR-ABL that is defective in transformation of myeloid cells, Tyr177Phe, was also found to be defective in raising intracellular ROS levels. Glucose metabolism in BCR-ABL-transformed cells is likely to be mediated by activation of the phosphatidylinositol-3'-kinase (PI3K) pathway, which is regulated through this site. Inhibition of PI3K or mTOR led to a significant decrease in ROS levels. Overall, our results suggest that elevated levels of ROS in BCR-ABL-transformed cells are secondary to a transformation-associated increase in glucose metabolism and an overactive mitochondrial electron transport chain and is specifically regulated by PI3K. Finally, these results hint at novel targets for drug development that may aid traditional therapy.

Benzamides↗
PubMed2004

Detection of BCR-ABL kinase mutations in CD34+ cells from chronic myelogenous leukemia patients in complete cytogenetic remission on imatinib mesylate treatment.

The BCR-ABL kinase inhibitor imatinib mesylate induces complete cytogenetic response (CCR) in a high proportion of chronic myelogenous leukemia (CML) patients. However, patients in CCR usually demonstrate evidence of residual BCR-ABL-positive progenitors. The mechanisms underlying persistence of small numbers of malignant progenitors in imatinib-sensitive patients are unclear. BCR-ABL kinase domain mutations affecting drug binding can lead to secondary resistance to imatinib. We show here that kinase mutations could be detected in CD34+ cells isolated from CML patients in CCR on imatinib. Most mutations seen have not been reported in previous clinical studies. Interestingly, several of the involved amino acid positions have been implicated in an in vitro mutagenesis screen. These BCR-ABL mutations were associated with varying levels of imatinib resistance. Two of 5 patients in whom mutations were detected on initial evaluation have relapsed. In addition, 4 patients in whom mutations were not initially detected, but with rising BCR-ABL mRNA levels on quantitative polymerase chain reaction (Q-PCR) analysis, had mutations detected on follow-up evaluation. We conclude that BCR-ABL kinase mutations can be detected in CD34+ cells from CML patients in CCR on imatinib, may contribute to persistence of small populations of malignant progenitors, and could be a potential source of relapse.

Adult↗
PubMed2004

Real-time quantitative PCR analysis can be used as a primary screen to identify patients with CML treated with imatinib who have BCR-ABL kinase domain mutations.

Mutations within the BCR-ABL kinase domain in imatinib-treated chronic myeloid leukemia (CML) are the main mechanism of acquired resistance. The early detection of mutations should provide clinical benefit by allowing early intervention. Quantitative polymerase chain reaction (RQ-PCR) results of BCR-ABL mRNA were correlated with mutation analysis in 214 patients treated with imatinib. We determined whether there was a difference in the incidence of mutations between the patients with a more than 2-fold rise in BCR-ABL and patients with stable or decreasing levels. Of the 56 patients with a more than 2-fold rise, 34 (61%) had detectable mutations (median rise, 3.0-fold; 25th-75th percentiles, 2.3-5.2). In 31 (91%) of these 34 patients, the mutation was present at the time of the rise and became detectable within 3 months in the remaining patients. Only 1 (0.6%) of 158 patients with stable or decreasing BCR-ABL levels had a detectable mutation, P less than .0001. Thus, a more than 2-fold rise identified 34 (97%) of 35 patients with a mutation. We conclude that a rise in BCR-ABL of more than 2-fold can be used as a primary indicator to test patients for BCR-ABL kinase domain mutations.

Benzamides↗
PubMed2006

Monitoring CML patients responding to treatment with tyrosine kinase inhibitors: review and recommendations for harmonizing current methodology for detecting BCR-ABL transcripts and kinase domain mutations and for expressing results.

The introduction in 1998 of imatinib mesylate (IM) revolutionized management of patients with chronic myeloid leukemia (CML) and the second generation of tyrosine kinase inhibitors may prove superior to IM. Real-time quantitative polymerase chain reaction (RQ-PCR) provides an accurate measure of the total leukemiacell mass and the degree to which BCR-ABL transcripts are reduced by therapy correlates with progression-free survival. Because a rising level of BCR-ABL is an early indication of loss of response and thus the need to reassess therapeutic strategy, regular molecular monitoring of individual patients is clearly desirable. Here we summarize the results of a consensus meeting that took place at the National Institutes of Health (NIH) in Bethesda in October 2005. We make suggestions for (1) harmonizing the differing methodologies for measuring BCR-ABL transcripts in patients with CML undergoing treatment and using a conversion factor whereby individual laboratories can express BCR-ABL transcript levels on an internationally agreed scale; (2) using serial RQ-PCR results rather than bone marrow cytogenetics or fluorescence in situ hybridization (FISH) for the BCR-ABL gene to monitor individual patients responding to treatment; and (3) detecting and reporting Philadelphia (Ph) chromosome-positive subpopulations bearing BCR-ABL kinase domain mutations. We recognize that our recommendations are provisional and will require revision as new evidence emerges.

Drug Monitoring↗
PubMed2001

BCR rearrangement-negative chronic myelogenous leukemia revisited.

PURPOSE: To document the characteristics of patients with major breakpoint cluster region (M-bcr) rearrangement-negative chronic myelogenous leukemia (CML). PATIENTS AND METHODS: The hematopathologist, who was blinded to patients' molecular status, reviewed the referral bone marrows and peripheral-blood smears from 26 patients with Philadelphia (Ph) translocation-negative CML who lacked Bcr rearrangement (and other evidence of a Bcr-Abl anomaly) and 14 patients (controls) with chronic-phase Ph-positive CML. Clinical data was ascertained by chart review. RESULTS: Among the 26 M-bcr rearrangement-negative CML patients, three pathologic subtypes emerged: (1) patients indistinguishable from classic CML (n = 9), (2) patients with atypical CML (n = 8), and (3) patients with chronic neutrophilic leukemia (n = 9). Among the 14 patients with Ph-positive CML who were included in the blinded review, 13 were classified as classic CML, and one was classified as atypical CML. The only statistically significant difference between M-bcr rearrangement-negative subgroups was in the proportion of patients having karyotypic abnormalities, an observation common only in patients with atypical CML (P = 0.008). However, the small number of patients in each subgroup limited our ability to differentiate between them. Interferon alfa induced complete hematologic remission in five of 14 patients; four of these remissions lasted more than 5 years. Only one of 26 patients developed blast crisis. The median survival of the 26 patients was 37 months. CONCLUSION: Patients with M-bcr rearrangement-negative CML fall into three morphologic subgroups. Disease evolution does not generally involve blastic transformation. Instead, patients show progressive organomegaly, leukocytosis, anemia, and thrombocytosis. Some patients in each subgroup can respond to interferon alfa.

Adult↗
PubMed2000

Quantitative evaluation of BCR-ABL amount of transcript post mobilization with G-CSF of peripheral blood stem cells from chronic myeloid leukemia patients in cytogenetic response.

We studied nine patients affected by chronic myeloid leukemia (CML Ph+ and bcr-abl positive) and treated with alpha-interferon (alpha-INF) in order to: first, to evaluate the feasibility of a mobilization of peripheral blood stem cells induced by granulocyte-colony-stimulating factor (G-CSF) and the contamination by Ph+ cells and second, to quantify the amount of bcr-abl leukemia associated transcript by a quantitative assay during mobilization procedures, and post mobilization follow-up. Eight achieved a complete karyotypic remission before mobilization obtained with discontinuation of alpha-INF for few days and G-CSF at a dosage of 15 microg/kg/day for 5-7 consecutive days. By quantitative-competitive polymerase chain reaction (QC-PCR) assay, all the leukaphereses and bone marrow samples during post mobilization follow up were studied to determine the amount of bcr-abl transcript. Karyotypic and molecular analysis on evaluable leukapheresis showed that all the harvests were Ph negative and bcr-abl positive: in seven cases the levels of bcr-abl transcript were higher or equal to the pre-apheresis status. In three out of four patients, who underwent more than one leukapheresis procedure, we noticed a decreasing amount of bcr-abl contamination from the first to the last apheresis. Our results suggest that in patients who achieved a complete or major cytogenetic conversion with alpha-INF, it is possible to obtain a sufficient amount of PBSC for autografting by leukapheresis following priming G-CSF therapy and that the amount of neoplastic transcript does not seem to increase.

Adolescent↗
PubMed2000

Novel oxime derivatives of radicicol induce erythroid differentiation associated with preferential G(1) phase accumulation against chronic myelogenous leukemia cells through destabilization of Bcr-Abl with Hsp90 complex.

Chronic myelogenous leukemia (CML) is a clonal disorder of a pluripotent hematopoietic stem cells characterized by a chimeric bcr-abl gene giving rise to a p210(Bcr-Abl) protein with dysregulated tyrosine kinase activity. Radicicol, a macrocyclic antifungal antibiotic, binds to the N-terminal of heat shock protein 90 (Hsp90) and destabilizes Hsp90-associated proteins such as Raf-1. This study investigated the effect of radicicol, novel oxime derivatives of radicicol (KF25706 and KF58333), and herbimycin A (HA), a benzoquinoid ansamycin antibiotic, on the growth and differentiation of human K562 CML cells. Although KF25706 and KF58333 induced the expression of glycophorin A in K562 cells, radicicol and HA caused erythroid differentiation transiently. Cell cycle analysis showed that G(1) phase accumulation was observed in K562 cells treated with KF58333. KF58333 treatment depleted p210(Bcr-Abl), Raf-1, and cellular tyrosine phosphorylated proteins in K562 cells, whereas radicicol and HA showed transient depletion of these proteins. KF58333 also down-regulated the level of cell cycle-dependent kinases 4 and 6 and up-regulated cell cycle-dependent kinase inhibitor p27(Kip1) protein without an effect on the level of Erk and Hsp90 proteins. Immunoprecipitation analysis showed that p210(Bcr-Abl) formed multiple complexes with Hsp90, some containing p23 and others Hsp70; KF58333 treatment dissociated p210(Bcr-Abl) from Hsp90/p23 chaperone complexes. Furthermore, KF58333 induced apoptosis in K562 cells and administration of KF58333 prolonged the survival time of SCID mice inoculated with K562 cells. These results suggest that KF58333 may have therapeutic potential for the treatment of CML that involves abnormal cellular proliferation induced by p210(Bcr-Abl).

Animals↗
PubMed2001

Direct relation between BCR-ABL tyrosine kinase activity and cyclin D2 expression in lymphoblasts.

Leukemia cells bearing the Philadelphia (Ph) chromosome express a Bcr-Abl fusion protein with deregulated protein tyrosine kinase (PTK) activity, which plays a central role in the malignant transformation. Many different signal transduction pathways are activated by Bcr-Abl, but little is known about their downstream targets in specific cell lineages. We show here that Ph-positive cell lines as well as primary cells derived from chronic myeloid leukemia (CML) in lymphoid blast crisis or from acute lymphoblastic leukemia (ALL) consistently express high levels of cyclin D2, whereas expression of this protein is low or absent in comparable Ph-negative lines and Ph-positive myeloid lines. Inhibition of Bcr-Abl with STI571 resulted in down-regulation of cyclin D2 and reduction of the number of cells in S phase, although complete G1 arrest was not induced. The expression of cyclin D2 in Ph-positive lymphoblasts was mediated via the phosphatidyl-inositol-3 kinase pathway. Analogous results were seen in murine BaF/3 cells transfected with a BCR-ABL expression vector. In contrast to the human cell lines, murine Baf/BCR-ABL cells exposed to STI571 inhibitor were all arrested in G1. This arrest could be abrogated by exogenous expression of cyclin D2 from a transfected cDNA construct. We conclude that a direct connection exists between Bcr-Abl PTK activity and cell cycle progression in which cyclin D2 plays a critical role. However, cell cycle progression in human Ph-positive lymphoid cells is not entirely dependent on Bcr-Abl PTK, and additional genetic lesions must be present.

Benzamides↗
PubMed2002

Effects of As(2)O(3) on BCR-ABL protein level and signal transduction in CML cells.

OBJECTIVE: To explore the effects of As(2)O(3) on BCR-ABL protein level and signal transduction in chronic myeloid leukemia (CML) cells. METHODS: Immunoprecipitation, protein tyrosine kinase (PTK) activity assay, real-time Taqman quantitative PCR and Western blot were used. RESULTS: As(2)O(3) downregulated BCR-ABL protein and STAT1 protein of CML mononuclear cells in the concentrations of 1.0 approximately 2.0 micro mol/L and 0.5 approximately 2.0 micro mol/L after 48 h exposure, respectively. However, p27 protein level was not affected. The PTK activity of BCR-ABL protein was also mildly decreased in CML monouclear cells at 60 h. The bcr-abl mRNA level remained unchanged. CONCLUSION: As(2)O(3) downregulats BCR-ABL protein, STAT1 protein, BCR-ABL signal transduction and PTK activity in CML cells.

Fusion Proteins, bcr-abl↗
PubMed2002

Imatinib mesylate (STI-571) reduces Bcr-Abl-mediated vascular endothelial growth factor secretion in chronic myelogenous leukemia.

A large and diverse spectrum of oncogenes has been implicated as a contributor to angiogenesis in solid tumors based, in part, on its ability to induce proangiogenic growth factors such as vascular endothelial growth factor (VEGF), and the fact that various anti-oncogenic signaling inhibitor drugs have been shown to reverse such proangiogenic effects both in vitro and in vivo. Because leukemias are now also considered to be angiogenesis-dependent malignancies, we asked whether a similar paradigm might exist for the BCR-ABL oncogene and the Bcr-Abl targeting drug, STI-571 (imatinib mesylate), in the context of chronic myelogenous leukemia (CML) cells. We found that levels of VEGF expression in BCR-ABL-positive K562 cells were reduced in vitro by treatment with STI-571 in a dose-dependent fashion. Transfection of BCR-ABL into murine myeloid 32D and human megakaryocyte MO7e hematopoietic cells resulted in enhanced VEGF expression, which could be further elevated by the exposure to cytokines such as interleukin 3 and granulocyte macrophage colony-stimulating factor. We also found that conditioned media taken from 32D-p210-transfected cells could stimulate human umbilical vein endothelial cells by increasing phosphorylation of VEGF-R2/KDR and the downstream serine/threonine kinase PKB/Akt, an important regulator of endothelial cell survival. Moreover, amplification of BCR-ABL in STI-571-resistant cells was associated with elevated VEGF expression levels which could be reversed by treatment with higher concentrations of STI-571. Taken together, our results implicate BCR-ABL as a possible regulator of CML angiogenesis and raise the possibility that STI-571 could mediate some of its anti-CML properties in vivo through an angiogenesis-dependent mechanism.

Animals↗
PubMed1992

The bcr-abl gene in chronic myelogenous leukaemia.

The observation made over 30 years ago that the Philadelphia chromosome is present in nearly all patients with CML led to the identification of a novel fusion gene bcr-abl. In the past few years, the biochemical and biological properties of bcr-abl have been extensively explored. Bcr sequences appear to activate c-abl for transformation by binding to the SH2 domain of c-abl in an intramolecular interaction, presumably interfering with the adjacent SH3 regulatory domain. Upon introduction into bone marrow cells, bcr-abl can cause acute or chronic leukaemias in mice and can stimulate the growth of many cell types, including multipotent stem cells, in vitro. Although their growth is stimulated, these cells are not fully malignant blastic leukaemias. The molecular events that occur during the progression to blast crisis of CML remain largely undefined, but existing animal models and in vitro culture systems will be useful for identifying or testing candidate genes. The study of tyrosine kinase oncogenes in general will probably lead to the identification of relevant bcr-abl substrates. The elucidation of these molecules as well as more downstream events in the bcr-abl signalling pathway offers the hope for novel therapeutic interventions to control Philadelphia chromosome leukaemias.

Animals↗
PubMed2006

[Using real-time polymerase chain reaction to quantitate bcr-abl mRNA].

BACKGROUND & OBJECTIVE: When leukemia patients achieve complete remission after chemotherapy, a few tumor cells still exist in other tissues outside bone marrow, which is called minimal residual disease (MRD), and it is the base of relapse. To cure leukemia, we should not only find MRD in time, but also quantitate MRD for instructing treatment and predicting prognosis. This study was to establish a real-time reverse transcription-polymerase chain reaction (RT-PCR) system to quantitate bcr-abl mRNA. METHODS: bcr-abl mRNA in leukemia cell line K562 was amplified by RT-PCR. T-A clone was used to construct the combined plasmid to be standard template; the standard curve of bcr-abl oncogene was drawn. bcr-abl mRNA in bone marrow samples of 16 chronic myelocytic leukemia (CML) patients was quantitated by this method. The sensitivity, stability, and repetition of this method were evaluated. RESULTS: The sensitivity is 10 copies of the recombined plasmid. The coefficient variations (CV) of repetition and stability were 2.19% and 3.21%. The correlation (R) of the standard curve was 0.984. The median bcr-abl level of the 16 CML patients was 4.58x10(4) kb/microg RNA. CONCLUSIONS: Real-time PCR has high sensitivity, repetition, and specificity. It can quantitate the copy number of bcr-abl oncogene.

Bone Marrow↗