scholarly journals GADD45a Is a Tumor Suppressor in BCR-ABL-Driven Leukemogenesis

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4530-4530
Author(s):  
Kaushiki Mukherjee ◽  
Xiaojin Sha ◽  
Tomasz Skorski ◽  
Ravi Bhatia ◽  
Barbara Hoffman ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Conflicts Of Interest ◽  
Multiple Stressors ◽  
Blast Crisis ◽  
Chronic Phase ◽  
Myelogenous Leukemia ◽  
Pcr Analysis ◽  
Wild Type ◽  
M Cell ◽  
The Status

Abstract The bcr-abl oncogene causes chronic myelogenous leukemia (CML). Growth arrest DNA damage 45a (Gadd45a) gene, a member in the gadd45 family of genes including Gadd45b & Gadd45g, is upregulated during myeloid lineage terminal differentiation. It is involved in G2/M cell cycle arrest and apoptosis in response to multiple stressors, including genotoxic and oncogenic stress . To investigate the effect of GADD45A in the development of CML, syngeneic wild type lethally irradiated mice were reconstituted with either wild type or gadd45a null myeloid progenitors transduced with a retrovirally expressed 210-kD BCR-ABL fusion oncoprotein. It was observed that loss of gadd45a accelerates BCR-ABL driven CML resulting in the development of a more aggressive AML like disease. Loss of Gadd45a resulted in increase of BCR-ABL expressing leukemic Stem/progenitor cells (GFP+Lin- cKit+Sca+). BCR-ABL transformed GADD45A deficient progenitors exhibit increased proliferation and decreased apoptosis, associated with enhanced PI3K-AKT-mTOR-4E-BP1 signaling and upregulation of p30C/EBPα and MCL-1 expression. Moreover, loss of Gadd45a was observed to facilitate transformation of BCR-ABL expressing BM cells to factor independence. These results provide novel evidence that gadd45a functions as a suppressor of BCR/ABL driven myeloid leukemogenesis. Since Gadd45a functions as a tumor suppressor in murine BCR-Abl driven leukemia, the status of Gadd45a mRNA expression levels was also investigated in human CML samples by utilizing real time PCR analysis. It was found that Gadd45a transcript levels were significantly up-regulated in chronic phase I CML samples. However in chronic phase-II, accelerated phase and blast crisis phase samples, expression was significantly down-regulated relative to normal controls. Thus, Gadd45a expression was observed to be altered in human CML samples correlating with disease progression. These results provide novel evidence that gadd45a functions as a suppressor of BCR/ABL driven myeloid leukemogenesis. These data also provide the impetus to further elucidate the role Gadd45a plays in suppressing the development of CML, and explore how its loss contributes to the progression of CML to a more aggressive leukemic phenotype. Disclosures No relevant conflicts of interest to declare.

GADD45a Is a Tumor Suppressor In BCR-ABL-Driven Leukemogenesis

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1467-1467
Author(s):  
Kaushiki Mukherjee ◽  
Xiaojin Sha ◽  
Ravi Bhatia ◽  
Tomasz Skorski ◽  
Barbara Hoffman ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Kinase Inhibitor ◽  
Conflicts Of Interest ◽  
Multiple Stressors ◽  
Blast Crisis ◽  
Chronic Phase ◽  
Myelogenous Leukemia ◽  
Pcr Analysis ◽  
M Cell ◽  
Number Of Patients

Abstract The BCR-ABL fusion oncogene which encodes a fused deregulated tyrosine kinase causes chronic myelogenous leukemia (CML) in humans. Imatinib, a small molecule ABL kinase inhibitor has been highly effective in treating chronic phase (CP) CML patients. However, a substantial number of patients undergo relapse due to development of resistance to imatinib therapy that leads to blast crisis (BC-CML), which is invariably fatal within weeks to months. Additional genetic aberrations assist in progression and identification of key players that are responsible for transformation is of utmost importance from a therapeutic point of view. Growth arrest DNA damage 45a (Gadd45a) gene, a member in the gadd45 family of genes including Gadd45b & Gadd45g, was identified as a myeloid differentiation primary response gene. There is evidence consistent with it’s involvement in G2/M cell cycle arrest and apoptosis in response to multiple stressors, including genotoxic and oncogenic stress. To investigate the effect of Gadd45a in the development of CML, adaptive bone marrow transplantation experiments with either wild type or Gadd45a null myeloid progenitors expressing 210-kD BCR-ABL fusion oncoprotein revealed that loss of Gadd45a accelerated BCR-ABL driven CML resulting in the development of a more aggressive AML/BC like disease. Recent newly obtained data indicate that number of Gadd45a deficient Leukemic stem cells (LSC) harboring BCR-ABL increased as disease progressed confirming Gadd45a as a crucial tumor suppressor in CML. Recent data also indicate, that transformed Gadd45a deficient progenitors exhibit increased proliferation and decreased apoptosis, associated with enhanced PI3K-AKT-mTOR-4E-BP1 signaling and upregulated oncogenic p30C/EBPα. More importantly, newly obtained data indicate that Gadd45a transcript levels in peripheral blood of human blast crisis (BC-CML) samples was found to be reduced compared to accelerated phase (AP-CML), chronic phase (CP-CML) and normal controls, assessed by Quantitative real time PCR analysis. Collectivly these data strongly suggest that Gadd45a expression is a novel prognostic indicator of CML progression, implicating Gadd45a as a downregulated target of BCR-ABL associated with progression to more aggressive stages. To conclude, our findings provide novel evidence that Gadd45a functions as a suppressor of BCR/ABL driven myeloid leukemogenesis, & that suppresion of Gadd45a is associated with CML progression. These data provide the impetus to further elucidate the role Gadd45a plays in suppressing the development of CML, and explore how its loss contributes to the progression of CML to more aggressive leukemic phenotypes. Disclosures: No relevant conflicts of interest to declare.

Loss of Stress Sensor GADD45a Accelerates BCR-ABL-Driven Leukemogenesis

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1668-1668
Author(s):  
Kaushiki Mukherjee ◽  
Xiaojin Sha ◽  
Ravi Bhatia ◽  
Barbara Hoffman ◽  
Dan Liebermann
Keyword(s):  
Conflicts Of Interest ◽  
Multiple Stressors ◽  
Chronic Phase ◽  
Human Growth ◽  
Myelogenous Leukemia ◽  
Pcr Analysis ◽  
Wild Type ◽  
M Cell ◽  
Cycle Arrest ◽  
The Status

Abstract Abstract 1668 The bcr-abl fusion oncogene causes chronic myelogenous leukemia (CML) in human. Growth arrest DNA damage 45a (Gadd45a) gene, a member in the gadd45 family of genes including Gadd45b & Gadd45g, is upregulated during myeloid lineage terminal differentiation. It is involved in G2/M cell cycle arrest and apoptosis in response to multiple stressors, including genotoxic and oncogenic stress. To investigate the effect of GADD45A in the development of CML, syngeneic wild type lethally irradiated mice were reconstituted with either wild type or gadd45a null myeloid progenitors transduced with a retrovirally expressed 210-kD BCR-ABL fusion oncoprotein. It was observed that loss of gadd45a accelerates BCR-ABL driven CML resulting in the development of a more aggressive AML like disease. BCR-ABL transformed GADD45A deficient progenitors exhibit increased proliferation and decreased apoptosis, associated with enhanced PI3K-AKT-mTOR-4E-BP1 signaling and upregulation of p30C/EBPα and MCL-1 expression. Since Gadd45a functions as a tumor suppressor in murine BCR-Abl driven leukemia, the status of Gadd45a mRNA expression levels was also investigated in human CML samples by utilizing real time PCR analysis. It was found that Gadd45a transcript levels were significantly upregulated in chronic phase CML samples. However in accelerated and blast phase samples, expression was significantly downregulated relative to normal controls. Thus, Gadd45a expression was observed to be altered in human CML samples correlating with disease progression. These results provide novel evidence that gadd45a functions as a suppressor of BCR/ABL driven myeloid leukemogenesis. These data also provide the impetus to further elucidate the role Gadd45a plays in suppressing the development of CML, and explore how its loss contributes to the progression of CML to a more aggressive leukemic phenotype. Disclosures: No relevant conflicts of interest to declare.

Loss of Stress Sensor GADD45a and GADD45b Accelerates BCR-ABL-Driven Leukemogenesis Via Distinct Signaling and Cellular Pathways.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1217-1217
Author(s):  
Xiaojin Sha ◽  
Barbara Hoffman ◽  
Dan Liebermann
Keyword(s):  
Bone Marrow ◽  
Cell Proliferation ◽  
Signaling Pathways ◽  
Conflicts Of Interest ◽  
Multiple Stressors ◽  
Myelogenous Leukemia ◽  
Ras Signaling ◽  
Wild Type ◽  
Cellular Pathways ◽  
Myeloid Progenitors

Abstract Abstract 1217 The bcr/abl oncogene causes chronic myelogenous leukemia (CML) in humans. BCR/ABL is known to localize to the cytoskeleton and to display a constitutively active tyrosine kinase activity that leads to the recruitment of downstream effectors of cell proliferation and survival. This is accomplished via several adapter proteins and signaling pathways, including Ras, PI3K-AKT, PkD2-NFkB and JAK-STAT5, all of which are believed to participate in the pathogenesis of CML. The complex nature of these signaling pathways and how they contribute to the initiation and progression of CML is only partially understood. The Gadd45 family of genes (Gadd45a, Gadd45b & Gadd45g) encode for small (18 kd) nuclear proteins that are rapidly induced by multiple stressors, including genotoxic and oncogenic stress. They are involved in G2/M cell cycle arrest and apoptosis in response to exogenous stress stimuli through MAPK and JNK/SAPK pathways. Furthermore Gadd45a has been identified as a mediator of oncogenic Ras signaling. GADD45 proteins are upregulated during myeloid lineage terminal differentiation. To investigate if and how GADD45A and GADD45B play a role in the development of CML, syngeneic wild type lethally irradiated mice were reconstituted with wild type, gadd45a or gadd45b null myeloid progenitors transduced with a retrovirally expressed 210-kD BCR/ABL fusion oncoprotein. It was observed that loss of gadd45a or gadd45b accelerates the development of BCR/ABL driven leukemia in wild type recipients. BCR/ABL transformed gadd45a or gadd45b deficient progenitor recipients exhibited significantly accelerated kinetics of increase in the number of WBC and percentage of myeloid blasts in blood compared to mice reconstituted with the same number of wild type bone marrow cells transduced with BCR/ABL. There was also increase in the rate of accumulation of CD11b+Gr1+ cells in the bone marrow and spleen. Using in vitro and in vivo BrdU assays, enhanced proliferation capacity was observed for BCR/ABL transduced gadd45a, but not gadd45b, deficient myeloid progenitors. However, impaired apoptosis was observed both in BCR/ABL transduced gadd45a and gadd45b deficient myeloid progenitors. These results indicate that both gadd45a and gadd45b function as suppressors of the development of BCR/ABL driven CML, where gadd45a appears to suppress CML via a mechanism involving both inhibition of cell proliferation and enhancement of apoptosis, whereas gadd45b appears to effect only apoptosis. Enhanced JNK signaling was observed in both gadd45a and gadd45b deficient progenitors, whereas enhanced p38 and AKT signaling was observed only in gadd45a deficient myeloid progenitors. Taken together, these data indicate that loss of either gadd45a or gadd45b accelerates BCR-ABL driven CML via distinct signaling and cellular pathways. Further elucidating the role Gadd45 stress sensors play in suppressing the development of leukemia should increase understanding of the molecular/cellular pathology BCR/ABL mediated leukemogenesis, and has the potential to lead to the development of new/improved modalities for treatment of leukemia. Disclosures: No relevant conflicts of interest to declare.

FLT3 Is Up-Regulated in Blast Crisis of Chronic Myeloid Leukemia and Combination of Small Interference RNA of FLT3 and Gleevec (STI571) Synergistically Induces the Apoptosis in K562 Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4532-4532
Author(s):  
Young Y. Lee ◽  
Kwang-Sung Ahn ◽  
Sung-Soo Yoon ◽  
Jung H. Choi ◽  
Byoung B. Park ◽  
...  
Keyword(s):  
Chronic Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Blast Crisis ◽  
Chronic Phase ◽  
K562 Cells ◽  
Pcr Analysis ◽  
Wild Type ◽  
Small Interference Rna ◽  
Expression Levels ◽  
Significant Difference

Abstract To identify a gene signature for prognostic markers at transition from chronic phase to blast crisis of chronic myeloid leukemia (CML), we have applied Affymetrix Genechips of 22,000 transcripts to analyze total RNA of CML cells from 12 patients with chronic phase and 12 patients with blast crisis. Data analysis using GeneSpring 6.0 generated a list of 143 differentially expressed genes. A total of 89 genes were up-regulated and 54 genes were down-regulated in blast crisis of CML, and vice versa in chronic phase of CML. Array data for 32 genes was validated using quantitative realtime PCR analysis. The expression levels of HSA6591, FLT3, NTE5, RSG1, LAF4, CPA3, ATF, FCGR3A, MYD88, IFIT1, TP73L, DTNA, MDA, and IL18R1 showed statistically significant difference (p < 0.05) between chronic phase and blast crisis. Since CML cells of blast crisis were generally unresponsive to STI571, we further analyzed roles of FLT3 which is known to be a poor prognositic marker in acute myeloid leukemia. For this experiment, K562 cells (CML blast cells) were transfected with small hairpin RNAs (shRNAs), also referred to as small interfering RNAs, to target human FLT3, resulting in the significant inhibition of FLT3 expression at mRNA and protein levels. MTT assay demonstrated that FLT3 knockdown K562 cells by shRNAs were more sensitive to STI571 compared to wild type of K562, although there was no difference at high concentration of STI571 (320 nM) between FLT3 knockdown K562 cells and wild type of K562 cells. The higher expression levels of apoptosis related genes (PARP, caspase-3, Bax) were observed in FLT3 knockdown K562 cells compared to wild type of K562 cells. Thus, RNA interference-directed targeting of FLT3 might be a novel treatment modality in STI571 refractory CML patients.

Computationally Designed, Small Molecule Inhibitors of Tubulin Inhibit the Growth of Gleevec Resistant Chronic Myelogenous Leukemia Cells.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2173-2173
Author(s):  
Anna Kalota ◽  
Alan M. Gewirtz
Keyword(s):  
Cell Growth ◽  
Small Molecules ◽  
Chronic Myelogenous Leukemia ◽  
Kinase Inhibitor ◽  
Blast Crisis ◽  
Chronic Phase ◽  
Free Energy Calculations ◽  
Myelogenous Leukemia ◽  
Leukemia Cells ◽  
Wild Type

Abstract The abl tyrosine kinase inhibitor (TKI) imatinib mesylate has revolutionized treatment of Chronic Myelogenous Leukemia (CML). Nonetheless, for the small percentage of chronic phase patients in whom resistance to imatinib develops, and for patients in accelerated phase/blast crisis, disease management is problematic. Second generation TKI may address the resistance issue, but serious cardiotoxicity might be a concern for all TKIs. We are therefore investigating other candidates for rationally directed CML therapy. Herein we report that targeting tubulin with computationally designed small molecules may prove useful for the treatment of TKI resistant CML cells. Tubulin inhibitors were obtained from Locus Pharmaceuticals, Blue Bell, PA. They were designed using a method that computes virtual inhibitor molecule binding efficiency after integrating free energy calculations from all chemically possible combinations of molecule fragment poses. Molecules that perform well in in silico screens are then synthesized for biological testing. We evaluated 3 such molecules (LP-261, LOC-011294, and LOC-011423), and 2 control compounds (LOC-007708, LP-590), on K562 human leukemia cells, murine BaF3 cells expressing wild type bcr-abl, or the Y253F, T315I, E255K, H296P and M351T kinase domain mutations (gift from B. Druker, Portland, Oregon), and on consenting donors of normal, and CML, bone marrow cells. LP-261, LOC-011294, and LOC-011423 all had significant activity in K562 cells and BaF3 cells expressing wild type bcr-abl. Inhibition of cell growth in these lines was ~90% when employed at concentrations of > 100nM. More importantly in BaF3 cells expressing each of the mutant abl kinases, including T315I, growth inhibition was also ~90%. Moreover, LP-261, and LOC-011294 were also highly effective against primary cells obtained from patients with chronic phase and blast crisis CML. Treatment of primary CML cells with LP-261 resulted in >80% inhibition of proliferation in all five CML patient samples when compared to control cells. LOC-011294 inhibited cell proliferation by >80% in 3 out of 5 primary patient samples, and by ~50% in one other. Additional testing revealed that LP-261 was not a substrate for the p-glycoprotein multi-drug resistance porter, and that it is orally bioavailable. Neither LOC-007708, (a selective inhibitor of p38 kinase), nor LP-590 (an inhibitor of p38, Flt-3 and tie-2 kinases) inhibited proliferation of the cells expressing mutated bcr-abl. Since these kinases are not thought to influence bcr-abl driven cell growth, these results were expected. In contrast, MOLM14 cells, which overexpress Flt-3, were profoundly inhibited by LP-590. Disease specificity is suggested by the fact that none of these compounds had any effect on growth of acute lymphoid leukemia (ALL) patient samples. To be clinically useful, it was important to demonstrate that normal CD34+ were less sensitive to the growth inhibitory effects of these compounds. For this purpose, normal CD34+ cells were exposed to LP-261, LOC-011294, and LOC-011423 for 24 hours at concentrations shown to inhibit CML cell growth and then plated in methylcellulose with cytokines. Under these conditions, no significant inhibition of CFU-GM, CFU-E, or BFU-E in comparison to control cells was shown. These results suggests that rationally designed anti-tubulin small molecules, alone, or in combination with other active agents, may prove quite useful for treating kinase inhibitor resistant, as well as de novo, CML. This hypothesis may be tested in the near future as an IND has been filed for LP-261.

scholarly journals MiR-300 Acts As a Tumor Supressor in Ph+ Progenitors By Modulating the JAK2-SET/PP2A/β-Catenin Interplay

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4529-4529
Author(s):  
Giovannino Silvestri ◽  
Justin Ellis ◽  
Lorenzo Stramucci ◽  
Jason G Harb ◽  
Paolo Neviani ◽  
...  
Keyword(s):  
Cell Lines ◽  
Molecular Mechanisms ◽  
Conflicts Of Interest ◽  
Blast Crisis ◽  
Chronic Phase ◽  
Myelogenous Leukemia ◽  
Leukemic Cells ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Dismal Prognosis

Abstract The persistence of tyrosine kinase inhibitor (TKI)-resistant malignant Philadelphia-positive (Ph+) hematopoietic stem cells (HSC) in chronic myelogenous leukemia (CML) TKI-treated patients in complete molecular remission, and the dismal prognosis of blast crisis CML indicate that the molecular mechanisms underlying its emergence, maintenance and progression are not totally dependent on the unrestrained kinase activity of BCR-ABL1 and might rely on other cell autonomous and/or microenvironmental signal capable of sustaining survival and self-renewal of the chronic phase and blast crisis Ph+ HSC compartment(s). We recently demonstrated that the Jak2/SET-PP2A/β-catenin pathway is essential for survival and self-renewal of quiescent TKI-resistant CD34+CD38- Ph+ HSC and that activation of such oncogenic signals requires the expression but not the activity of BCR-ABL1. Because microRNAs (miRNAs) are likely to control in a canonical and/or decoy manner the expression of different components of the Jak2 signalosome, this makes them an attractive target for further understanding the mechanisms of leukemogenesis and, perhaps, for developing new alternative therapies that selectively eradicate quiescent leukemic HSCs. In silico analysis revealed that a specific miR subset shares multiple targets of the BCR-ABL1/Jak2/SET-PP2A signalosome. Nanostring Array analysis performed on primary bone marrow cells from normal individuals and chronic phase or blast crisis CML patients revealed that expression of some of these miRNA is altered in CML. For example, expression of miR-300 and miR-101, which are predicted to simultaneously modulate directly Jak2, hnRNP-A1 and β-catenin and, indirectly, other molecules of the BCR-ABL1/Jak2/SET-PP2A/β-catenin pathway, is significantly inhibited in chronic phase CML and further decreases in advanced CML samples. Additionally, miR-300 expression is several folds lower in dividing (div. 1) compared to quiescent (CFSEMAX) CD34+ CML cells. Lentiviral-transduction of miR-300 in human BCR-ABL+ cell lines resulted in marked downmodulation of JAK2, β-Catenin hnRNPA1 and SET and, as expected, in increased PP2A activity. Moreover, ectopic miR-300 expression decreased reduced clonogenic potential and proliferation, and increased susceptibility to TKI (e.g. Imatinib) induced apoptosis. Interestingly, it appears that forced BCR-ABL1 expression in TF-1 leukemic cells decreases miR-300, consistent with the reported activation in these cells of the Jak2-SET-PP2A-β-catenin pathway. Altogether our results suggest that miR-300 expression and, potentially, that of other deregulated non-coding RNAs might be dispensable or deleterious for the phenotype of Ph+ progenitors and/or indispensable for that of Ph+ HSCs. Thus, experiments in BCR-ABL1 cell lines as well as primary stem and progenitor cell fractions are currently ongoing to assess the role of this and other miRNAs in survival, self-renewal/proliferation of CML stem and progenitor cells. Disclosures No relevant conflicts of interest to declare.

scholarly journals Genomic instability of microsatellite repeats and its association with the evolution of chronic myelogenous leukemia [see comments]

Blood ◽  
1994 ◽  
Vol 83 (12) ◽  
pp. 3449-3456 ◽  
Author(s):  
C Wada ◽  
S Shionoya ◽  
Y Fujino ◽  
H Tokuhiro ◽  
T Akahoshi ◽  
...  
Keyword(s):  
Genomic Instability ◽  
Chronic Myelogenous Leukemia ◽  
Blast Crisis ◽  
Chronic Phase ◽  
Genetic Alterations ◽  
Myelogenous Leukemia ◽  
Leukemic Cells ◽  
Genetic Event ◽  
Familial Predisposition ◽  
Somatic Instability

Abstract Tumorigenesis has been shown to proceed through a series of genetic alterations involving protooncogenes and tumor-suppressor genes. Investigation of genomic instability of microsatellites has indicated a new mechanism for human carcinogenesis in hereditary nonpolyposis colorectal cancer and sporadic cancer and this instability has been shown to be related to inherited predisposition to cancer. This study was conducted to determine whether such microsatellite instability is associated with the evolution of chronic myelogenous leukemia (CML) to the blast crisis. Nineteen CML patients clinically progressing from the chronic phase to accelerated phase or blast crisis and 20 other patients in the CML chronic phase were studied. By polymerase chain reaction assay, DNAs for genomic instability in five separate microsatellites in chromosome arms 5q (Mfd27), 17p (Mfd41), 18q (DCC), 3p (CI3–9), and 8p (LPL) were examined. Differences in unrelated microsatellites of chronic and blastic phase DNAs in 14 of 19 patients (73.7%) were demonstrated. Somatic instability in five microsatellites, Mfd27, Mfd41, DCC, CI3–9, and LPL, was detected in 2 of 19 (10.5%), 8 of 19 (42.1%), 11 of 19 (57.9%), 4 of 17 (23.5%), and 4 of 17 (23.5%) cases. In 10 of 19 cases (52.6%), genetic instability in at least two of five microsatellites was observed and was categorized as replication error (RER+) phenotype. CML evolution cases with myeloid, lymphoid, and mixed phenotypes and the blast crisis and accelerated phase showed somatic instability in a number of microsatellites. No alterations in leukemic cells at the chronic phase could be detected in any microsatellites. These data indicate instability of microsatellites (RER+) but not familial predisposition to possibly be a late genetic event in the evolution of CML to blast crisis. In the microsatellite of the DCC gene, complicated alterations in band patterns caused by instability as well as loss of heterozygosity (LOH) were observed in 13 of 19 cases (68.4%): instability in 9 cases, instability plus LOH in 2 cases, and only LOH in 2 cases. These highly frequent alterations in microsatellites, including instability and LOH, suggesting that secondary events due possibly to loss of fidelity in replication and repair machinery may be significantly associated with CML evolution.

scholarly journals Mutations of the N-ras gene in juvenile chronic myelogenous leukemia

Blood ◽  
1994 ◽  
Vol 83 (8) ◽  
pp. 2248-2254 ◽  
Author(s):  
J Miyauchi ◽  
M Asada ◽  
M Sasaki ◽  
Y Tsunematsu ◽  
S Kojima ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Chronic Myelogenous Leukemia ◽  
Blast Crisis ◽  
Gene Mutations ◽  
Chronic Phase ◽  
Myelogenous Leukemia ◽  
Disease Stage ◽  
Nucleotide Sequence Analysis ◽  
Age Group ◽  
Ras Gene

Juvenile chronic myelogenous leukemia (JCML), a myeloproliferative disorder of childhood, is distinct from adult-type chronic myelogenous leukemia (CML) and bears resemblance to chronic myelomonocytic leukemia (CMMoL). Since mutations in the N-ras gene have been found at high frequencies in CMMoL, but only rarely in CML, we analyzed mutations activating the N-ras gene in 20 patients with JCML. We used the strategy for analysis of gene mutations based on in vitro DNA amplification by polymerase chain reaction (PCR) followed by single- strand conformation polymorphism (SSCP) analysis and/or direct sequence analysis. Nucleotide sequence analysis showed single nucleotide substitutions involving codons 12, 13, or 61 in six of 20 patients (30%). Four of six patients with mutations were in chronic phase and the other two in blast crisis, indicating no apparent correlation with disease stage. Most of the patients with mutations were in the older age group with poor prognosis, although one patient in the younger age group also harbored the mutation. These data suggest that N-ras gene mutations may be involved in the pathogenesis and/or prognosis of JCML and provide further evidence that JCML is an entity distinct from CML.

Several Bcr-Abl kinase domain mutants associated with imatinib mesylate resistance remain sensitive to imatinib

Blood ◽  
2003 ◽  
Vol 101 (11) ◽  
pp. 4611-4614 ◽  
Author(s):  
Amie S. Corbin ◽  
Paul La Rosée ◽  
Eric P. Stoffregen ◽  
Brian J. Druker ◽  
Michael W. Deininger
Keyword(s):  
Imatinib Mesylate ◽  
Kinase Inhibitor ◽  
Blast Crisis ◽  
Chronic Phase ◽  
Kinase Domain ◽  
Myelogenous Leukemia ◽  
Imatinib Resistance ◽  
Abl Kinase ◽  
Cellular Assays ◽  
Kinase Domain Mutations

Abstract Imatinib mesylate is a selective Bcr-Abl kinase inhibitor, effective in the treatment of chronic myelogenous leukemia. Most patients in chronic phase maintain durable responses; however, many in blast crisis fail to respond, or relapse quickly. Kinase domain mutations are the most commonly identified mechanism associated with relapse. Many of these mutations decrease the sensitivity of the Abl kinase to imatinib, thus accounting for resistance to imatinib. The role of other mutations in the emergence of resistance has not been established. Using biochemical and cellular assays, we analyzed the sensitivity of several mutants (Met244Val, Phe311Leu, Phe317Leu, Glu355Gly, Phe359Val, Val379Ile, Leu387Met, and His396Pro/Arg) to imatinib mesylate to better understand their role in mediating resistance.While some Abl mutations lead to imatinib resistance, many others are significantly, and some fully, inhibited. This study highlights the need for biochemical and biologic characterization, before a resistant phenotype can be ascribed to a mutant.

BCR Rearrangement–Negative Chronic Myelogenous Leukemia Revisited

2001 ◽  
Vol 19 (11) ◽  
pp. 2915-2926 ◽  
Author(s):  
Razelle Kurzrock ◽  
Carlos E. Bueso-Ramos ◽  
Hagop Kantarjian ◽  
Emil Freireich ◽  
Susan L. Tucker ◽  
...  
Keyword(s):  
Chronic Myelogenous Leukemia ◽  
Blast Crisis ◽  
Chronic Phase ◽  
Interferon Alfa ◽  
Myelogenous Leukemia ◽  
Disease Evolution ◽  
Number Of Patients ◽  
Significant Difference ◽  
Atypical Cml ◽  
Peripheral Blood Smears

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.

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