BCR/ABL alters the function of NK cells and the acquisition of killer immunoglobulin-like receptors (KIRs)

Blood ◽  
2003 ◽  
Vol 101 (9) ◽  
pp. 3527-3533 ◽  
Author(s):  
Elena G. Chiorean ◽  
Scott J. Dylla ◽  
Krista Olsen ◽  
Todd Lenvik ◽  
Yvette Soignier ◽  
...  

Natural killer (NK) cells decrease in function during chronic myelogenous leukemia (CML) progression from chronic phase to blast crisis, and they can becomeBCR/ABL+ late in the disease course. To study this altered function, NK92 cells were transduced with the BCR/ABL oncogene. In contrast to the parental cells, which died when deprived of interleukin 2 (IL-2), p210+ NK92 cells proliferated and survived indefinitely in the absence of IL-2. BCR/ABL also decreased the natural cytotoxicity of NK92 cells against K562 targets, without affecting IL-2, interferon γ (IFN-γ), or tumor necrosis factor α (TNF-α) production. Although the ABL-specific tyrosine kinase inhibitor imatinib mesylate (STI-571) had no effect on parental NK92 cells, it markedly decreased the growth and survival of IL-2–independent p210+ NK92 cells. In contrast to the parental cell line, serial analysis of p210+ NK92 cells detected small populations that clonally expressed one or more killer immunoglobulin-like receptors (KIRs). Unlike the decreased natural cytotoxicity, the function of the activating CD158j receptor remained intact. Southern blotting and hybridization with an enhanced green fluorescence protein (eGFP) probe showed that KIR− and KIR+ NK92 cells were all derived from the same clone, suggesting that KIR acquisition remains dynamic at the maturational stage represented by the NK92 cell line. When tested in primary CD56+bright NK cells, p210 induced partial IL-2–independent growth and increased KIR expression similar to findings in NK92 cells. This is the first study to show thatBCR/ABL, well known for its effects on the myeloid lineage, can alter the function of lymphoid cells, which may be associated with the defect in innate immunity associated with CML progression.

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

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.


Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1669-1669
Author(s):  
Franck E. Nicolini ◽  
Françoise Huguet ◽  
Hélène Labussière-Wallet ◽  
Yann Guillermin ◽  
Madeleine Etienne ◽  
...  

Abstract Abstract 1669 Most epidemiologic studies performed in chronic myelogenous leukemia (CML) relate that the disease occurs preferentially in males with a sex ratio of ∼1.2. In addition, CML can be diagnosed in young adults and masculine fertility is a matter of concern, particularly because tyrosine kinase inhibitors (TKI) may impact on spermatogenesis by a selective inhibition of Src kinases, PDGF-R and c-kit. Sperm cryopreservation is recommended by some authors at diagnosis in males that would expect to have children later on. In a retrospective analysis we have analysed the spermograms of 62 chronic phase (CP) and 2 onset blast crisis (BC) CML males referred to our 3 centres between 2001 and 2012, collected at diagnosis before TKI treatment, and we have compared the results obtained to those of 15 healthy volunteer donors from the cryopreservation bank database, after informed consent. In 10 patients we could collect some data for patients being on imatinib mesylate (IM). CML patients had a median age of 31 (16–48) years, significantly younger than that in the control group of healthy donors: 37 (34–45) years (p=0.001). Sokal scores were 24% high, 27% intermediate and 49% low for evaluable patients (13 patients unknown or not available). The median BCR-ABLIS value at diagnosis was 77.65%. Patients had a median duration of 26 (0–38) days of hydroxyurea prior to commencing any TKI and 65% of evaluable patients had HU before TKI. None of the patients got interferon prior to TKI. The semen cryopreservation was performed within a median of 10 (2–102) days after CML diagnosis and after a median abstinence of 5 (0.5–30) days. The median volume of semen obtained in CML patients was 2.95 (0.5–14.9) ml and 3 (1.4–5.3) ml for normal donors (p=0.3). Williams test showed 72 (0–87)% of necrospermia in patients versus 18 (4–32)% in donors (p=0.00003). The median number of spermatozoa obtained was not different in patients [46 (0.03–200) 106/ml] than that in donors [74 (19.2–253) 106/ml] (p=0.24), as well as the number of spermatozoa per ejaculate observed (p=0.49). The motility of spermatozoa at 30 minutes after collection was not different between patients (median = 47.5%) and donors (median = 50%) (p=0.12), however higher numbers of atypical spermatozoa were observed in patients [median = 77.5 (16–100)%] rather than in donors [median = 45% (22–89)%], p=0.008, and the multiple abnormalities index (MAI) was significantly higher in patients [median = 1.99 (1.14–2.7)] than that in donors [median = 1.33 (1.09–1.55)], p=0.00006. There was no correlation between age at diagnosis, Sokal index and the number of spermatozoa per ml obtained (p=0.7 and 0.21 respectively). Ten CP CML patients had spermograms after a median of 1440 (9–1456) days of IM treatment and the results obtained were compared to i) the results of each individual patient at CP diagnosis and ii) to the results of healthy comparators. In comparison to the characteristics observed at diagnosis, the semen volume (median = 3.1 ml), Williams test (median = 65%), the motility at 30 minutes (median = 37.5%) and the MAI (median = 1.71) were not different (p=ns for all), however, the numbers of spermatozoa (median = 14.9 106/ml and = 37.05 ml per ejaculate) collected on IM were significantly lower (p=0.014 and p=0.045 respectively). The different parameters evaluated on IM were compared to those of normal controls and showed significant alterations. The semen volume was not different (p=0.94), neither the motility of spermatozoa (p=0.24), but the Williams test was highly perturbed on IM [median 65 (24–79)% versus 18 (4–32)% in donors] p=0.00003, as well as the numbers of spermatozoa as 106 per ml, collected on IM [median 14.9 (0.67–179)) versus normal [74 (19.2–253)], p=0.0036 or as 106 per ejaculate collected on IM [median 37.5 (2.68–572.8)) versus normal [149 (30–535.3)], p=0.026. Atypical forms were significantly more abundant on IM [median = 80 (68–90)%] versus healthy controls [median = 45% (22–89)], p=0.0058. Finally, the MAI was severely altered on IM [median = 1.71 (1.61–1.98)] versus normal individuals [median = 1.33 (1.09–1.55)], p=0.00013. In conclusion, this work demonstrates the existence of significant sperm alterations in young males with CML at diagnosis of undetermined origin, prior to any treatment. These alterations persist on IM treatment and little is know about the impact of second generation TKI. Thus the most appropriate approach remains a matter of debate in thus setting. Disclosures: Nicolini: Novartis, Bristol Myers-Squibb, Pfizer, ARIAD, and Teva: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Huguet:Novartis, BMS: Speakers Bureau. Michallet:Novartis, Pfizer, Teva, Genzyme, Janssen Cilag, BMS, Merck, Pfizer, Gilead, Alexion: Consultancy, Speakers Bureau. Etienne:Novartis, Pfizer, speaker for Novartis, BMS: Consultancy.


Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1467-1467
Author(s):  
Kaushiki Mukherjee ◽  
Xiaojin Sha ◽  
Ravi Bhatia ◽  
Tomasz Skorski ◽  
Barbara Hoffman ◽  
...  

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.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2170-2170
Author(s):  
Francis Giles ◽  
Philipp le Coutre ◽  
Kapil Bhalla ◽  
Gianantonio Rosti ◽  
G.J. Ossenkopplele ◽  
...  

Abstract Nilotinib is a potent, highly selective, aminopyrimidine inhibitor which in vitro is 30-fold more potent than imatinib and active against 32/33 imatinib resistant cell lines with Bcr-Abl mutations. This open-label study was designed to evaluate the efficacy and safety as defined by hematologic and cytogenetic response rates (HR/CyR) of nilotinib administered at a daily dose of 400 mg bid to patients who previously received and either failed or were intolerant to imatinib and dasatinib. A total of 50 patients were enrolled and included CP (n=26), AP (n=10), and BC (n=14) patients. Of the 14 BC patients 10 were myeloid and 4 were lymphoid. Overall 8 (16%) patients had extramedullary disease at baseline. The median age was 57 (range 19–78) years and the median time from first diagnosis of CP, AP, or BC to treatment was 65 (range 8–213) months. The median duration of nilotinib exposure was 226 (range 3–379) days. A total of 28 (56%) patients remain on treatment, 22 (44%) discontinued (6 for adverse events, 11 for disease progression, 3 withdrew consent, and there were 2 deaths related to cerebral hemorrhages). Complete (HR) was reported in 9 of the 20 (45%) CP patients who did not have a CHR at baseline. Of the 26 CP patients, 8 (31%) had a major CyR (2 complete and 6 partial), 2 (8%) patients had minimal responses, and 9 (35%) patients had no response. Disease progression occurred in one CP patient and 6 patients were not evaluable. Confirmed hematologic responses were observed in 2 of 10 (20%) AP patients who had a return to chronic phase (RTC), 7 patients were not evaluable and there was one patient death. Of the 10 AP patients 1 (10%) each had CyR (partial, minor, minimal and no response). Of the 14 BC patients 1 had a CHR (7%), 2 (14%) had a return to chronic phase (RTC), 6 (43%) were not assessable for response, and 5 (36%) had progressive disease. Overall the most frequent Grade 3 or 4 adverse events reported were thrombocytopenia in 12 (24%), neutropenia in 11 (22%), and anemia in 5 (10%) patient. In summary, nilotinib has significant clinical activity and an acceptable safety and tolerability in CML-CP, AP, and BC patients who were resistant or intolerant to imatinib and have also failed dasatinib therapy.


Blood ◽  
1985 ◽  
Vol 66 (5) ◽  
pp. 1053-1061 ◽  
Author(s):  
M Nitta ◽  
Y Kato ◽  
A Strife ◽  
M Wachter ◽  
J Fried ◽  
...  

Peripheral blood specimens were obtained from 22 patients with Philadelphia chromosome (Ph1) positive chronic myelogenous leukemia (CML) (16 in chronic phase, 2 in an accelerated phase, and 4 in blast crisis). Studies were performed to determine the frequency of the presence of the Ph1 chromosome in cells of lymphoid lineages. Rosetted (E+) lymphocytes (T lymphocytes) from nine patients in chronic phase and one patient in blast crisis were stimulated with T cell growth factor interleukin 2 (IL-2) and/or phytohemagglutinin (PHA). All ten patients had sufficient T lymphocyte metaphases for analysis and of a total of 461 metaphases examined, only one contained the Ph1 chromosome. Nucleated cells of density less than 1.077 g/mL were infected with Epstein-Barr virus (EBV). Following infection, cell lines were established from individual colonies attached to egg albumin- coated Lab-Tek slide chambers (clonal cell lines) or from suspension culture in 96-well tissue culture cluster dishes (nonclonal cell lines). Cell surface and intracellular marker analysis confirmed the B lymphocyte phenotype of all the cell lines examined. B lymphoblastoid cell lines were established from 16 of the 22 patients. All lines from 12 patients were Ph1-negative. From two chronic phase patients, both Ph1-positive and Ph1-negative lines were established. From one patient in an accelerated phase, only Ph1-positive lines were established. From another patient in blast crisis (of myeloblastic phenotype), only Ph1- positive lines were established initially; however, five months later, after the patient had been treated with mitoxantrone, only Ph1-negative lines were derived from this patient. Based on these results, it appears that most B cells and mature T cells in most CML patients are Ph1-negative, but that about 25% of patients have predominantly Ph1- positive B cells or a mixture of Ph1-positive and Ph1-negative B cells that are capable of growing as established cell lines after transformation with EBV.


Blood ◽  
1990 ◽  
Vol 76 (2) ◽  
pp. 401-408 ◽  
Author(s):  
C Verfaillie ◽  
N Kay ◽  
W Miller ◽  
P McGlave

Abstract We have compared the proliferative and cytotoxic capacities of a highly purified population of recombinant interleukin-2 (rIL-2)-activated peripheral blood mononuclear cells (PBMNC), termed adherent lymphokine- activated killer cells (A-LAK), in 15 chronic phase (CP) and 10 advanced disease (AD) Ph-positive chronic myelogenous leukemia (CML) patients. The selective enrichment of CML A-LAK cells depended on their propensity to adhere to plastic and to proliferate when cultured in the presence of rIL-2 for 14 days. In both CP and AD patients, 14-day culture resulted in growth of a uniform population of large granular lymphocytes. While less than 10% of the A-LAK cells were CD56-/CD3+ (mature T lymphocytes), 82% +/- 12% of A-LAK cells from early CP patients (diagnosed less than 1 year from study), 84% +/- 3% of A-LAK cells from late CP patients (studied greater than 1 year after diagnosis), and 87% +/- 3% of A-LAK cells from AD patients were CD56+/CD3- (activated natural killer [NK] cells). No bcr gene rearrangement could be found in A-LAK cells from 13 CP and six AD CML patients studied. A-LAK cells from seven early CP CML patients displayed similar cytotoxicity against K562 (80% +/- 7% lysis at effector:target ratio of 20:1) and against Raji (80% +/- 12% lysis) compared with A-LAK from 17 normal individuals (72% +/- 3% K562 lysis, P = .21; 74% +/- 5% Raji lysis, P = .39). However, the cytotoxicity of A-LAK cells from eight late CP patients (59% +/- 5% K562 lysis, P = .02; 52% +/- 8% Raji lysis, P = .02) and that of 10 AD patients studied at any point after diagnosis (31% +/- 3% K562 lysis, P less than .001; 25% +/- 6% Raji lysis, P less than .001) was significantly lower than that of seven early CP CML patients and 17 normals. The proliferative potential of A-LAK cells from seven early CP CML patients (291 +/- 191- fold) was significantly greater than that of A-LAK cells from 17 normal individuals (23 +/- 3-fold, P = .03), eight late CP patients (46 +/- 17- fold, P = .02), and 10 AD patients (5.4 +/- 1.9-fold, P = .01). In contrast to CML A-LAK, K562 cytotoxicity of unstimulated mature peripheral blood NK cells was significantly lower in early CP CML patients than in normals and remained low at all stages of disease.


Blood ◽  
1985 ◽  
Vol 66 (5) ◽  
pp. 1053-1061 ◽  
Author(s):  
M Nitta ◽  
Y Kato ◽  
A Strife ◽  
M Wachter ◽  
J Fried ◽  
...  

Abstract Peripheral blood specimens were obtained from 22 patients with Philadelphia chromosome (Ph1) positive chronic myelogenous leukemia (CML) (16 in chronic phase, 2 in an accelerated phase, and 4 in blast crisis). Studies were performed to determine the frequency of the presence of the Ph1 chromosome in cells of lymphoid lineages. Rosetted (E+) lymphocytes (T lymphocytes) from nine patients in chronic phase and one patient in blast crisis were stimulated with T cell growth factor interleukin 2 (IL-2) and/or phytohemagglutinin (PHA). All ten patients had sufficient T lymphocyte metaphases for analysis and of a total of 461 metaphases examined, only one contained the Ph1 chromosome. Nucleated cells of density less than 1.077 g/mL were infected with Epstein-Barr virus (EBV). Following infection, cell lines were established from individual colonies attached to egg albumin- coated Lab-Tek slide chambers (clonal cell lines) or from suspension culture in 96-well tissue culture cluster dishes (nonclonal cell lines). Cell surface and intracellular marker analysis confirmed the B lymphocyte phenotype of all the cell lines examined. B lymphoblastoid cell lines were established from 16 of the 22 patients. All lines from 12 patients were Ph1-negative. From two chronic phase patients, both Ph1-positive and Ph1-negative lines were established. From one patient in an accelerated phase, only Ph1-positive lines were established. From another patient in blast crisis (of myeloblastic phenotype), only Ph1- positive lines were established initially; however, five months later, after the patient had been treated with mitoxantrone, only Ph1-negative lines were derived from this patient. Based on these results, it appears that most B cells and mature T cells in most CML patients are Ph1-negative, but that about 25% of patients have predominantly Ph1- positive B cells or a mixture of Ph1-positive and Ph1-negative B cells that are capable of growing as established cell lines after transformation with EBV.


Blood ◽  
1990 ◽  
Vol 76 (2) ◽  
pp. 401-408 ◽  
Author(s):  
C Verfaillie ◽  
N Kay ◽  
W Miller ◽  
P McGlave

We have compared the proliferative and cytotoxic capacities of a highly purified population of recombinant interleukin-2 (rIL-2)-activated peripheral blood mononuclear cells (PBMNC), termed adherent lymphokine- activated killer cells (A-LAK), in 15 chronic phase (CP) and 10 advanced disease (AD) Ph-positive chronic myelogenous leukemia (CML) patients. The selective enrichment of CML A-LAK cells depended on their propensity to adhere to plastic and to proliferate when cultured in the presence of rIL-2 for 14 days. In both CP and AD patients, 14-day culture resulted in growth of a uniform population of large granular lymphocytes. While less than 10% of the A-LAK cells were CD56-/CD3+ (mature T lymphocytes), 82% +/- 12% of A-LAK cells from early CP patients (diagnosed less than 1 year from study), 84% +/- 3% of A-LAK cells from late CP patients (studied greater than 1 year after diagnosis), and 87% +/- 3% of A-LAK cells from AD patients were CD56+/CD3- (activated natural killer [NK] cells). No bcr gene rearrangement could be found in A-LAK cells from 13 CP and six AD CML patients studied. A-LAK cells from seven early CP CML patients displayed similar cytotoxicity against K562 (80% +/- 7% lysis at effector:target ratio of 20:1) and against Raji (80% +/- 12% lysis) compared with A-LAK from 17 normal individuals (72% +/- 3% K562 lysis, P = .21; 74% +/- 5% Raji lysis, P = .39). However, the cytotoxicity of A-LAK cells from eight late CP patients (59% +/- 5% K562 lysis, P = .02; 52% +/- 8% Raji lysis, P = .02) and that of 10 AD patients studied at any point after diagnosis (31% +/- 3% K562 lysis, P less than .001; 25% +/- 6% Raji lysis, P less than .001) was significantly lower than that of seven early CP CML patients and 17 normals. The proliferative potential of A-LAK cells from seven early CP CML patients (291 +/- 191- fold) was significantly greater than that of A-LAK cells from 17 normal individuals (23 +/- 3-fold, P = .03), eight late CP patients (46 +/- 17- fold, P = .02), and 10 AD patients (5.4 +/- 1.9-fold, P = .01). In contrast to CML A-LAK, K562 cytotoxicity of unstimulated mature peripheral blood NK cells was significantly lower in early CP CML patients than in normals and remained low at all stages of disease.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2173-2173
Author(s):  
Anna Kalota ◽  
Alan M. Gewirtz

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.


Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 4804-4804
Author(s):  
Suchitra Basu ◽  
Yaling Qiu ◽  
Fan Dong

Abstract Chronic myelogenous leukemia (CML) is a clonal hematopoietic disorder caused by the BCR/ABL fusion oncogene. CML typically evolves in three distinct clinical stages: chronic and accelerated stages and blast crisis. The progression of CML from chronic phase (CP) to blast crisis (BC) is characterized by the increasing failure of myeloid precursors to differentiate into mature granulocytes and aggressive proliferation of immature myeloid cells. It has been shown that CML progression from CP to BC is associated with downregulation of C/EBPs including C/EBPa and C/EBPe, critical regulators of myeloid development. Forced expression of C/EBPs suppresses transformation and restores granulocytic differentiation of BCR/ABL-expressing myeloid cells, suggesting that downregulation of C/EBPs may be involved in CML transition from CP to BC. The proto-oncogene Gfi-1 encodes a nuclear zinc-finger transcriptional repressor that is required for the survival and proliferation of myeloid cells. We recently showed that expression of a dominant negative Gfi-1 mutant, N382S, led to markedly increased expression of C/EBPe in myeloid cells, suggesting that Cebpe encoding C/EBPe is a Gfi-1 target. We investigated the possibility that inhibition of Gfi-1 function in BCR/ABL-expressing cells may increase C/EBPe expression, thereby exerting a negative effect on BCR/ABL-mediated transformation. Myeloid 32D cells transfected with BCR/ABL (32D/BCR/ABL) are independent of IL-3 for proliferation and survival. Expression of the N382S mutant in 32D/BCR/ABL cells (32D/N382S) had a significant inhibitory effect on proliferation and survival in the absence of IL-3, but only a weak effect in the presence of IL-3, suggesting that the N382S mutant specifically inhibited BCR/ABL-mediated proliferation and survival. The level of C/EBPe protein was markedly augmented in 32D/N382S cells. Interestingly, when cultured in medium containing no growth factors, 32D/N382S cells exhibited certain features of macrophage differentiation including increased cell size, adherence to the surface of culture flasks, spreading and increased surface expression of macrophage differentiation marker F4/80. 32D/N382S cells also became more sensitive to c-ABL kinase inhibitor imatinib. These data indicate that Gfi-1 may play an important role in BCR/ABL-mediated transformation and thus represent a potential therapeutic target in the treatment of CML.


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