scholarly journals Distinct associations of NEDD4L expression with genetic abnormalities and prognosis in acute myeloid leukemia

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ming-qiang Chu ◽  
Liu-chao Zhang ◽  
Qian Yuan ◽  
Ting-juan Zhang ◽  
Jing-dong Zhou
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
White Blood Cells ◽  
Normal Karyotype ◽  
Human Cancers ◽  
Genetic Abnormalities ◽  
Public Data ◽  
Frequent Event ◽  
Acute Myeloid

Abstract Background There is mounting evidence that demonstrated the association of aberrant NEDD4L expression with diverse human cancers. However, the expression pattern and clinical implication of NEDD4L in acute myeloid leukemia (AML) remains poorly defined. Methods We systemically determined NEDD4L expression with its clinical significance in AML by both public data and our research cohort. Moreover, biological functions of NEDD4L in leukemogenesis were further tested by in vitro experiments. Results By the public data, we identified that low NEDD4L expression was correlated with AML among diverse human cancers. Expression of NEDD4L was remarkably decreased in AML compared with controls, and was confirmed by our research cohort. Clinically, low expression of NEDD4L was correlated with greatly lower age, higher white blood cells, and higher bone marrow/peripheral blood blasts. Moreover, NEDD4L underexpression was positively correlated with normal karyotype, FLT3 and NPM1 mutations, but negatively associated with complex karyotype and TP53 mutations. Importantly, the association between NEDD4L expression and survival was also discovered in cytogenetically normal AML patients. Finally, a number of 1024 RNAs and 91 microRNAs were identified to be linked to NEDD4L expression in AML. Among the negatively correlated microRNAs, miR-10a was also discovered as a microRNA that may directly target NEDD4L. Further functional studies revealed that NEDD4L exhibited anti-proliferative and pro-apoptotic effects in leukemic cell line K562. Conclusions Our findings indicated that NEDD4L underexpression, as a frequent event in AML, was associated with genetic abnormalities and prognosis in AML. Moreover, NEDD4L expression may be involved in leukemogenesis with potential therapeutic target value.

Aberrant Expression of the Homeobox Gene CDX2 in Acute Myeloid Leukemia.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 8-8 ◽  
Author(s):  
Claudia Scholl ◽  
Dimple Bansal ◽  
Konstanze Dohner ◽  
Karina Eiwen ◽  
Benjamin H. Lee ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Cell Lines ◽  
Myeloid Leukemia ◽  
Gene Copy ◽  
Coding Region ◽  
Aberrant Expression ◽  
Cdx2 Expression ◽  
Frequent Event ◽  
Acute Myeloid

Abstract The caudal-type homeobox transcription factor 2 (CDX2) plays an important role in embryonic development and regulates the proliferation and differentiation of intestinal epithelial cells in the adult. Ectopic expression of CDX2 in the hematopoietic compartment was previously identified as the key pathogenetic event in a single patient with acute myeloid leukemia (AML) and t(12;13)(p13;q12). Using real-time quantitative PCR, we detected aberrant CDX2 expression in 153 (90%) of 170 patients with AML, in patients with high-risk myelodysplastic syndrome or advanced-stage chronic myeloid leukemia, and in several AML cell lines, but not in bone marrow derived from normal individuals. Expression of CDX2 was monoallelic in the majority of cases with informative single-nucleotide polymorphisms in the CDX2 coding region, but was not related to mutations in the CDX2 coding region or in the predicted CDX2 promoter sequence, gene-specific hypomethylation of the CDX2 promoter, or increased CDX2 gene copy numbers. Stable knockdown of CDX2 expression by lentivirus-mediated RNA interference inhibited the proliferation of various human AML cell lines exhibiting CDX2 transcript levels that were in the range of those observed in most primary AML samples, and strongly reduced their clonogenic potential in vitro. Primary murine hematopoietic progenitor cells transduced with Cdx2 acquired serial replating activity in vitro, could be continuously propagated in liquid culture, generated a fully penetrant and transplantable AML in vivo, and displayed dysregulated expression of Hox family members. Together, these results (i) demonstrate that aberrant expression of CDX2 is a frequent event in myeloid leukemogenesis, (ii) suggest a role for CDX2 as part of a common effector pathway that increases the proliferative capacity and promotes the self-renewal potential of hematopoietic progenitors, and (iii) support the unifying hypothesis that CDX2 is responsible, at least in part, for abnormalities in HOX gene expression in AML.

scholarly journals Study on the Relativity between Cytogenetics and Cytomorphology and its Prognosis Significance in Children with Acute Myelogenous Leukemia

2018 ◽  
Vol 10 (2) ◽  
pp. 35-41
Author(s):  
S Mehta ◽  
S Singh ◽  
Wang Ning Ling
Keyword(s):  
Acute Myeloid Leukemia ◽  
Survival Rate ◽  
Myeloid Leukemia ◽  
Remission Rate ◽  
White Blood Cells ◽  
Normal Karyotype ◽  
Myelogenous Leukemia ◽  
Banding Technique ◽  
Abnormal Karyotype ◽  
Acute Myeloid

Objective: The main objective of this study was to retrospectively evaluate that the cytogenetic abnormalities is an important prognostic factor for the cure of acute myeloid leukemia (AML).Methods: This retrospective study enrolled newly diagnosed 70 cases (37 males and 33 females, aged 10.1 months to 14.5 years) of pediatric patients with AML during 2010 January - 2016 February from the Second Affiliated Hospital of Anhui Medical University. Excluding criteria were cases secondary to treatment-related MDS and AML. Samples were obtained from bone marrow cells in patients after treatment on the anterior superior iliac spine, blood diseases laboratory by direct culture or 24/48 hour short-term culture, G -banding technique for testing. Follow-up of 1 - 60 months, the analysis of treatment response rates of different karyotypes, distribution ratios in various subtypes, normal karyotype and abnormal karyotype. ISPSS17.0 software statistics was used for statistical analysis. Groups were compared using chi-square test; Survival rate was calculated by method of Kaplan Meier and survival difference between groups were compared with breslow test.Results: Among 70 cases, 42 cases were detected for chromosomal abnormalities (i.e. 60% of the total number of cases), M3 abnormal karyotype distortion rate of 78.5%, M2 abnormal karyotype aberrations 63.3%, M4 60.0%, M1 50%, M5 lowest 38.9 %, M7 nuclear aberrations highest rate was 100%. Total chromosomal aberration rate was 60%. Acute myeloid leukemia cases, t (8; 21) at most, there are 15 cases, and the presence of abnormal karyotype 86.7% in the original part of differentiated myeloid leukemia (M2); t (15; 17) has 11 cases, exists only in acute promyelocytic cell leukemia (M3). After treatment, the remission rate of t (8; 21) was 80%; the remission rate of t (15; 17) was 90%; the remission rate of other abnormal karyotype abnormalities was 50%; the remission rate of total abnormal karyotype was 71.4%. The event free survival rate was significantly different between normal karyotype, t (8; 21), t (15; 17) and other abnormal karyotype groups (P<0.05).Conclusions: Acute myeloid leukemia karyotype abnormalities among FAB subtypes are different; M3 is the highest rate of abnormal karyotype aberrations, M2, M4 medium, M5 minimum. t (15; 17) seen in acute promyelocytic leukemia (APL), prognosis is good; t (8; 21) is more common in M2, prognosis is good, also found in M4 and M5, worse prognosis; +8 Abnormalities found in AML M2, M3, M4, M5 and M6 subtypes, prognosis medium; inv (16) high white blood cells, low platelet poor prognosis, AML patients with normal karyotype prognosis medium. J-GMC-N | Volume 11 | Issue 01 | January-June 2018, Page: 35-41

Differences in Cyto- and Molecular Genetic Abnormalities between Children <2 Years and Older Children with Acute Myeloid Leukemia.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1830-1830
Author(s):  
Brian V. Balgobind ◽  
Iris H. Hollink ◽  
Dirk Reinhardt ◽  
Jutta Bradtke ◽  
Andrea Teigler-Schlegel ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Young Children ◽  
Myeloid Leukemia ◽  
Molecular Genetic ◽  
Age Groups ◽  
Normal Karyotype ◽  
Older Children ◽  
Ras Mutations ◽  
Genetic Abnormalities ◽  
Acute Myeloid

Abstract Young children (defined as &lt;2 years old) with acute myeloid leukemia (AML) do not differ in outcome when compared with older children with AML. Previously, distinct cytogenetic aberrations specific for AML in young children have been reported, such as t(7;12), and t(1;22), which is found exclusively in FAB M7. Moreover, young children with AML are characterized by a high frequency of 11q23-rearrangements. However, so far, no information is available on differences in the molecular genetic background of these two age groups. We therefore retrospectively investigated the distribution of different cytogenetic and molecular aberrations in a large cohort (n=435) of pediatric AML cases, of which 75 (17%) were young children. The predominant cytogenetic aberration in infant AML consisted of 11q23-rearrangements, which occurred in 44% of young children versus 17% in older children (p=&lt;0.005), without differences in the distribution of 11q23-translocation partners. We also found significant differences in other cytogenetic subgroups of AML between young and older children, i.e. normal karyotype, 5% vs. 18%, respectively (p=0.008) and complex karyotype, 12% vs. 5% (p=0.03). t(7;12) (n=3) and t(8;16) (n=3) were only detected in young children, in contrast to t(15;17) (n=16) and t(8;21) (n=44), which were only seen in older children. Patients were also screened for molecular abnormalities, including the mutational hotspots of c-KIT (n=229), FLT3 (n=230), N-RAS (n=187), K-RAS (n=187), PTPN11 (n=216), MLL-partial tandem duplications (MLL-PTD) (n=240) and NPM1 (n=291). In the overall cohort, a significantly different age distribution was found for NPM1 mutations (0% young vs. 9% in older children; p=0.05) and FLT3-ITD (0% vs. 21%, respectively; p=0.005). Mutations in the other genes showed no clear correlation with age. Several non-random associations between molecular and cytogenetic abnormalities were detected. 89% of c-KIT mutations were associated with core-binding factor AML in children ≥2 years old. In young children, 2/4 c-KIT-mutated cases were associated with an MLL-rearrangement. NPM1 and FLT3-ITD mutations in older children were significantly correlated with normal karyotype AML (57% of NPM1 mutations, and 75% of FLT3/ITD; p=&lt;0.005). In young children, 71% of RAS mutations were associated with an 11q23-rearrangement vs. 28% in older children (p=0.08). In older children however, 41% of the RAS mutations were associated with a normal karyotype. These data suggest that young children with AML are characterized by differences in the type and frequency of cytogenetic and molecular genetic abnormalities when compared with older children with AML, possibly reflecting differences in underlying biology between these age-groups. These differences may become clinically relevant in the era of molecularly targeted therapy.

Acute Myeloid Leukemia Induced by MLL-ENL Is Cured by Oncogene Ablation despite Acquisition of Complex Genetic Abnormalities

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3109-3109
Author(s):  
Sarah J. Horton ◽  
Vanessa Walf-Vorderwülbecke ◽  
Steve J. Chatters ◽  
Neil J. Sebire ◽  
Jasper de Boer ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Constitutive Expression ◽  
Leukemic Cells ◽  
Fusion Activity ◽  
Genetic Abnormalities ◽  
Conditional Expression ◽  
Acute Myeloid

Abstract Chromosomal translocations involving the Mixed-Lineage-Leukemia (MLL) gene on chromosome 11q23 are frequent in infant acute leukemia and give rise to the formation of MLL-fusion genes. Several studies have addressed the importance of MLL-fusion activity for the initiation and maintenance of hematopoietic transformation. However, the dependence of established leukemias on MLL-fusion activity has not been previously addressed. We have developed a model for conditional expression of MLL-ENL in hematopoietic progenitor cells, in which expression of the fusion oncogene is turned off by doxycycline. In this study, immortalized myeloid cells conditionally or constitutively expressing the MLL-ENL fusion gene were used to induce acute myeloid leukemia (AML) in vivo. Primary recipients developed AML with a mean latency of 81.4 (±4.8) days. Secondary recipients developed AML with much shorter latencies than primary recipients regardless of whether the leukemic cells were freshly transplanted (26.8 (±6.8) days) or cultured in vitro for one month prior to transplantation (18 (±3.9) days). Genetic analysis revealed that some leukemic cells had acquired gross chromosomal abnormalities such as trisomy 6 or gains and losses of chromosome regions, which were not detected in the immortalised cells from which they were derived. Despite the acquisition of additional genetic abnormalities, the leukemic cells remained dependent upon MLL-ENL expression in vitro and in vivo. The leukemic cells terminally differentiated into neutrophils upon doxycycline treatment in vitro and established leukemias regressed following administration of doxycycline to recipient mice in their drinking water. Leukemic regression was accompanied by the complete loss of leukemic cells from the peripheral blood and differentiation of leukemic cells in the spleen. In 7 out of 34 doxycycline treated mice, remission was not sustained and the leukemias relapsed. However, most of these were shown to have acquired constitutive expression of MLL-ENL. This study demonstrates that leukemic cells are addicted to MLL-ENL expression and suggests that targeting the transcriptional/signalling networks established by MLL-fusion oncogenes in patients with 11q23 rearrangements would be a major therapeutic advance.

Activating FLT3 Mutations Display a Wide Range Of Transforming Potential and a Characteristic Pathway Profile Associated With Prognosis In Acute Myeloid Leukemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 1312-1312
Author(s):  
Hanna Janke ◽  
Friederike Schneider ◽  
Daniela Schumacher ◽  
Tobias Herold ◽  
Hopfner Karl-Peter ◽  
...  
Keyword(s):  
Gene Expression ◽  
Acute Myeloid Leukemia ◽  
Tyrosine Kinase ◽  
Gene Expression Profile ◽  
Myeloid Leukemia ◽  
Normal Karyotype ◽  
Wide Range ◽  
Flt3 Mutations ◽  
Acute Myeloid

Abstract Background Internal tandem duplication (ITD) and pointmutations in the tyrosine kinase domain (TKD) of the receptor tyrosine kinase FLT3 occur in about 30% of patients with acute myeloid leukemia (AML). In contrast to the negative prognostic impact of FLT3-ITD in normal karyotype AML, FLT3 pointmutations occurring in the TKD and juxtamembrane (JM) region are less frequent and of unclear clinical impact. Although TKD mutations can induce resistance to tyrosine kinase inhibitors the individual transforming potential of FLT3 pointmutations has not been analysed in detail. In this study we have performed a comprehensive analysis of various FLT3 mutants in a comparative setting in vitro and analyzed gene expression profiles, and clinical outcome with respect to FLT3mutation status. Material and Methods We analyzed relapse and survival in 672 cytogenetically normal AML patients and the FLT3 status at diagnosis and relapse in 156 patients. In the murine Ba/F3 cell model we analyzed the transforming potential, subcellular localization, phosphorylation status and signaling properties of eight different FLT3 mutants. The investigated FLT3 mutations include three ITD of different length and insertion site, V592A in the JM region, common FLT3-TKD mutations D835V and D835Y as well as D839G and I867S in the second TKD. FLT3-D839G and -I867S were recently found in AML patients by our group during routine diagnostics but have not been functionally characterized before. The corresponding remission samples did not express these mutations. Further a gene expression profile analysis with respect to FLT3-ITD and -TKD mutation status and evaluation of differences in activation of predefined STAT5 target gene set was performed. Results In 672 normal karyotype AML patients FLT3-ITD, but not FLT3-TKD mutations were associated with an inferior relapse free and overall survival in multivariate analysis. In paired diagnosis-relapse samples FLT3-ITD showed higher stability (70%) compared to FLT3-TKD (30%). In vitro, FLT3-ITD induced a fully transformed phenotype in Ba/F3 cells, whereas FLT3 pointmutations showed a weaker but clearly transformed phenotype with gradual increase in proliferation and protection from apoptosis. The transforming capacity of the investigated mutants was associated with cell surface expression and tyrosine 591 phosphorylation of the FLT3 receptor. Western blot experiments revealed STAT5 activation only in FLT3-ITD transformed cells, further gene expression profile analyses displayed differences in predefined STAT5 target genes between FLT3-ITD and FLT3-TKD mutations. In contrast, FLT3-non-ITD mutants had an enhanced signal of AKT and MAPK activation. Further differences were found on mRNA level presenting deregulation of SOCS2, ENPP2, PRUNE2 and ART3 expression between FLT3-ITD, FLT3-TKD and FLT3-WT. Conclusion Although apparently divergent in response to treatment all functionally characterized mutants showed a clear gain-of-function phenotype with a wide range of transforming activity associated with clinical prognosis and signaling. Disclosures: No relevant conflicts of interest to declare.

Comprehensive Analysis of Genetic Alterations in Acute Myeloid Leukemia According to the WHO Classification.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 4311-4311
Author(s):  
Yuichi Ishikawa ◽  
Hitoshi Kiyoi ◽  
Akane Tsujimura ◽  
Yasusi Miyazaki ◽  
Masao Tomonaga ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Who Classification ◽  
Normal Karyotype ◽  
Genetic Alterations ◽  
P53 Mutation ◽  
Npm1 Mutation ◽  
Multilineage Dysplasia ◽  
Genetic Abnormalities ◽  
Acute Myeloid

Abstract Acute myeloid leukemia (AML) is a heterogeneous clonal disorder of hematopoietic progenitor cells, and is thought to be the consequence of two broad complementation classes of mutations: those that confer a proliferative and/or survival advantage to hematopoietic progenitors, and those that impair hematopoietic differentiation and confer properties of self-renewal. To date, several genetic alterations, which are involved in the pathophysiology of the AML development, have been apparent, and some of them have been disclosed to have an impact on the clinical management. Therefore, it is required to establish the detailed classification of AML according to the genetic status. In this study, we comprehensively analyzed the genetic alterations in AML patients in comparison with the WHO classification. The study population included 115 newly diagnosed AML patients consisting of 25 recurrent genetic abnormalities, 25 multilineage dysplasia, 7 therapy-related and 56 not otherwise categorized WHO subcategories. Bone marrow samples were obtained from the patients after obtaining informed consent for banking and molecular analyses. Mutations in FLT3, cKIT, NPM1, N-RAS, p53, C/EBPa, AML1 and AKT1 genes were analyzed as previously described. In consistent with previous reports, FLT3 (20.9%), NPM1 (14.8%) and C/EBPa (13.0%) mutations were frequently observed, while no AKT1 mutation was found. Furthermore, NPM1 mutation was not found in AML with recurrent genetic abnormalities and C/EBPa mutation was not found in AML with recurrent genetic abnormalities or therapy related. Nine cases have double mutations of FLT3 and NPM1 genes, and 3 have FLT3 and C/EBPa mutations. Of note is that 15 of 25 (60%) AML with multilineage dysplasia cases have at least one mutation in p53, NPM1, C/EBPa, FLT3, N-RAS and AML1 genes and that p53 mutation was selectively found in the cases with complex karyotype. However, 4 AML with multilineage dysplasia cases with normal karyotype did not have any mutations in the analyzed genes. Comprehensive genetic analysis clarifies the detailed molecular base of AML and could make the subdivision of the WHO classification by combining the analysis for clinical impacts. Especially, mutation status in p53, NPM1 and C/EBPa genes seems to be useful for the subdivision of the AML with multilineage dysplasia, which is the most heterogeneous subcategory in the WHO classification.

Hypoxia-Inducible Factor-1 Alpha (HIF-1α) and HIF-2α Are Independent Prognostic Factors for Normal Karyotype Acute Myeloid Leukemia (NK AML)

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2553-2553
Author(s):  
Kellie M. Demock ◽  
Joseph Marinaro ◽  
Ian McInnis ◽  
Laurie Ann Ford ◽  
Meir Wetzler ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Hypoxia Inducible Factor ◽  
Normal Karyotype ◽  
Mrna Levels ◽  
Normal Bone Marrow ◽  
Normal Bone ◽  
Acute Myeloid

Abstract Emerging data has shown that severe hypoxia in vitro selects for highly immature or therapy-resistant leukemia clones and may be a crucial component of leukemia stem cell niches. One mechanism utilized by normal cells to survive hypoxia is upregulation of hypoxia inducible factor-1α (HIF-1α), a master transcription factor that directly transactivates genes important for cellular responses to hypoxia including angiogenesis and anaerobic metabolic pathways. HIF-1α is rapidly degraded under normoxia but is stabilized and synthesized under hypoxia or following malignant transformation. Overexpression of HIF-1α protein is associated with increased patient (pt) mortality in multiple solid cancer types, and with worse clinical outcome in pediatric acute lymphoblastic leukemia; however, its role in acute myeloid leukemia (AML) is unknown. First, we examined the response of human AML cells in vitro to hypoxic stress. We found that in vitro exposure of human AML cell lines (HEL, HL60/VCR) with low baseline HIF-1α levels to hypoxia (≤1% O2, 5%CO2) resulted in significantly increased HIF-1α mRNA levels after 4 hours followed by increased HIF-1α protein and elevated VEGF-A and VEGFR-1 mRNA levels peaking at 8 hours. We then examined expression of HIF-1α and a related hypoxia factor, HIF-2α, in diagnostic marrow samples from 91 consecutive AML pts (46% male, 54% female) treated at our institute from 1995–2005. As karyotype is the most important prognostic factor in AML, we examined only normal karotype AML samples associated with intermediate prognosis. Median patient age was 66 years (range 21–87). Less than half (n=46, 49%) achieved complete remission (CR) following induction chemotherapy. Median overall survival (OS) was 9.6 months. HIF-1α and HIF-2α levels were measured by Q-PCR and expressed relative to normal bone marrow controls (level of mRNA expression=1). HIF-1α protein expression was also evaluated by immunohistochemistry (IHC) and qualified as nuclear vs. cytoplasmic. We found that HIF-1α mRNA levels were consistently higher in AML cells than normal bone marrow controls (median fold change 2.78; range 0.48–22.89), although HIF-1α protein levels was increased in only a minority of samples. In contrast, HIF-2α mRNA levels were consistently lower in AML samples than normal bone marrow (median 0.14; range 0.7–0.42). Univariate analysis demonstrated that age, CR, and nuclear HIF-1α protein expression by IHC (p=0.0081) impacted OS. Significant factors for event free survival (EFS) were age, CR, and cytoplasmic HIF-1α IHC expression (p=0.0422). Multivariate analysis demonstrated that age, CR, cytoplasmic HIF-1α IHC expression (p=0.0056; HR=0.22; 95% CI=0.07–0.64) and HIF-2α mRNA expression (p=0.0101; HR=0.16; 95% CI=0.04–0.65) were independent predictors for OS. Similarly, age, CR, cytoplasmic HIF-1α IHC expression (p=0.0302; HR=0.26; 95% CI=0.08–0.88), and HIF-2α mRNA levels (p=0.0016, HR 0.08, 95% CI= 0.02–0.39) were also independent factors for EFS. Conclusions: Our results are the first to demonstrate that overexpression of HIF-1α and HIF-2α are independent prognostic factors in normal karyotype AML (constituting 40–49% of all adult AML diagnoses). Given the fact that HIF expression can be upregulated by oncogenes and tumor suppressors, additional studies examining potential correlations between HIF-1/2α expression and FLT-3/NPM-1 gene mutations in NK-AML; and in other prognostic AML subgroups (i.e. AML with recurrent or complex cytogenetics) are warranted. Based on these data, inhibition of HIF-1/2α mediated pathways with targeted agents may represent a future means to improve clinical outcome for subsets of AML patients.

scholarly journals Association of ABCB1 polymorphisms with survival and in vitro cytotoxicty in de novo acute myeloid leukemia with normal karyotype

2010 ◽  
Vol 12 (2) ◽  
pp. 111-118 ◽  
Author(s):  
H Gréen ◽  
I J Falk ◽  
K Lotfi ◽  
E Paul ◽  
M Hermansson ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
De Novo ◽  
Normal Karyotype ◽  
Acute Myeloid

Heterogeneity of Acute Myeloid Leukemia at the Stem Cell Level.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1355-1355
Author(s):  
Michael Heuser ◽  
Laura Sly ◽  
Courteney Lai ◽  
Malina Leung ◽  
Grace Lin ◽  
...  
Keyword(s):  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Critical Role ◽  
Normal Karyotype ◽  
Complex Karyotype ◽  
Gm Csf ◽  
Limiting Dilution ◽  
Acute Myeloid

Abstract Leukemias are considered hierarchically organized being maintained by a leukemia stem cell (LSC). Whereas LSCs become the primary focus for targeted therapies, little is known about the pathways regulating LSC fidelity. Using retroviral gene transfer of MN1, NUP98HOXD13 (ND13), or HOXA9 oncogenes and limiting-dilution transplantation we modelled leukemias with different LSC frequencies, and characterized critical signaling pathways by loss-of-function analysis. Here we establish the concept that LSCs are heterogeneous based on the number of activated transcriptional networks, and functionally characterize downstream targets that are critical for LSC activity. Constitutive expression of the very potent myeloid oncogene MN1 with the ND13 fusion gene in murine bone marrow cells results in acute myeloid leukemia (AML) that is phenotypically very similar to MN1-induced AML. However, limiting dilution analysis showed that the LSC frequency was 33 fold higher in MN1+ND13 cells compared to MN1 cells, and disease latency at the limiting dilution was significantly shorter in the combination model (p=.009). Whereas MN1-LSCs expanded 68-fold over a period of 6 days, MN1+ND13-LSCs expanded 131-fold more than MN1-LSCs as determined by the competitive repopulation unit (CRU) assay. To screen for functional differences of the two models we screened for differential cytokine responses in vitro. Interestingly, MN1+ND13 expressing cells proliferated in response to GM-CSF, whereas MN1 cells or ND13 cells did not. This was confirmed as well for MN1+HOXA9 expressing cells and their MN1+CTL or HOXA9+CTL expressing counterparts. We found that Stat1, Stat3, Stat5, and Erk1/2 were selectively phosphorylated upon cytokine stimulation in MN1+ND13 and MN1+HOXA9 cells compared to single-oncogene transduced cells. To test the role of Stat1 and Stat5b for LSC fidelity Stat1 −/− and Stat5b −/− cells were co-transduced with MN1 and HOXA9 and compared to wildtype cells in vitro and in vivo. Stat1 −/− cells transduced with MN1+HOXA9 proliferated slower than wildtype cells in response to GM-CSF but not with IL3/IL6/SCF. Proliferation of Stat5b −/− cells transduced with MN1+HOXA9 proliferated slower than wildtype cells in response to both GM-CSF and IL3/IL6/SCF (p&lt;.05). CRU assays with MN1+HOXA9-transduced Stat1 −/− and Stat5b −/− cells demonstrated that the day 6 CRU was 6 and 77 fold reduced, respectively, compared to wildtype cells. As MN1 and HOXA9 are upregulated in distinct subsets of normal karyotype AML we speculated that their combined overexpression may model subsets of complex karyotype AML. We performed gene set enrichment analysis on cytogenetic subsets of previously published gene expression data from 285 AML patients. 12 of 13 Stat-related pathways were enriched in complex karyotype patients compared to 4 and 8 of 13 Stat-related pathways in inv(16) and normal karyotype AML, respectively, thus supporting a critical role of Stat activation in LSCs of AML with multiple active pathways like complex karyotype AML. In conclusion we demonstrate considerable heterogeneity of LSC fidelity depending on the number of activated oncogenes and establish a critical role of Stat1 and Stat5b in mediating this LSC fidelity. Stat1 and Stat5b may become important therapeutic targets in complex karyotype AML.

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