scholarly journals Key pathways are frequently mutated in high-risk childhood acute lymphoblastic leukemia: a report from the Children's Oncology Group

Blood ◽  
2011 ◽  
Vol 118 (11) ◽  
pp. 3080-3087 ◽  
Author(s):  
Jinghui Zhang ◽  
Charles G. Mullighan ◽  
Richard C. Harvey ◽  
Gang Wu ◽  
Xiang Chen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Acute Lymphoblastic Leukemia ◽  
High Risk ◽  
B Cell ◽  
High Frequency ◽  
Lymphoblastic Leukemia ◽  
Cell Development ◽  
B Cell Development ◽  
Ras Signaling ◽  
Somatic Alterations

Abstract We sequenced 120 candidate genes in 187 high-risk childhood B-precursor acute lymphoblastic leukemias, the largest pediatric cancer genome sequencing effort reported to date. Integrated analysis of 179 validated somatic sequence mutations with genome-wide copy number alterations and gene expression profiles revealed a high frequency of recurrent somatic alterations in key signaling pathways, including B-cell development/differentiation (68% of cases), the TP53/RB tumor suppressor pathway (54%), Ras signaling (50%), and Janus kinases (11%). Recurrent mutations were also found in ETV6 (6 cases), TBL1XR1 (3), CREBBP (3), MUC4 (2), ASMTL (2), and ADARB2 (2). The frequency of mutations within the 4 major pathways varied markedly across genetic subtypes. Among 23 leukemias expressing a BCR-ABL1-like gene expression profile, 96% had somatic alterations in B-cell development/differentiation, 57% in JAK, and 52% in both pathways, whereas only 9% had Ras pathway mutations. In contrast, 21 cases defined by a distinct gene expression profile coupled with focal ERG deletion rarely had B-cell development/differentiation or JAK kinase alterations but had a high frequency (62%) of Ras signaling pathway mutations. These data extend the range of genes that are recurrently mutated in high-risk childhood B-precursor acute lymphoblastic leukemia and highlight important new therapeutic targets for selected patient subsets.

Precursor B Cell Acute Lymphoblastic Leukemia Induces Pro-Leukemic Changes in the Bone Marrow Microenvironment That Contribute to Therapeutic Resistance

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1466-1466
Author(s):  
Christopher D Chien ◽  
Elizabeth D Hicks ◽  
Paul P Su ◽  
Haiying Qin ◽  
Terry J Fry
Keyword(s):  
Bone Marrow ◽  
Acute Lymphoblastic Leukemia ◽  
B Cells ◽  
B Cell ◽  
Lymphoblastic Leukemia ◽  
Cell Development ◽  
B Cell Development ◽  
Bone Marrow Microenvironment ◽  
Therapeutic Resistance

Abstract Abstract 1466 Pediatric acute lymphoblastic leukemia (ALL) is the most common childhood malignancy. Although cure rates for this disease are approximately 90%, ALL remains one of the leading causes cancer-related deaths in children. Thus, new treatments are needed for those patients that do not respond to or recur following standard chemotherapy. Understanding the mechanisms underlying resistance of pediatric ALL to therapy offers one approach to improving outcomes. Recent studies have demonstrated the importance of communication between cancer cells and their microenvironment and how this contributes to the progression and therapeutic resistance but this has not been well studied in the context of ALL. Since the bone marrow is presumed to be the site of initiation of B precursor ALL we set out in our study to determine how ALL cells utilize the bone marrow milieu in a syngeneic transplantable model of preB cell ALL in immunocompetent mice. In this model, intravenously injected preB ALL develops first in the bone marrow, followed by infiltration into the spleen, lymph node, and liver. Using flow cytometry to detect the CD45.2 isoform following injection into B6CD45.1+ congenic recipients, leukemic cells can be identified in the bone marrow as early as 5 days after IV injection with a sensitivity of 0.01%-0.1%. The pre-B ALL line is B220+/CD19+/CD43+/BP1+/IL-7Ralpha (CD127)+/CD25-/Surface IgM-/cytoplasmic IgM+ consistent with a pre-pro B cell phenotype. We find that increasing amounts of leukemic infiltration in the bone marrow leads to an accumulation of non-malignant developing B cells at stages immediately prior to the pre-pro B cell (CD43+BP1-CD25-) and a reduction in non-malignant developing pre B cells at the developmental stage just after to the pre-pro B cell stage (CD43+BP1+CD25+). These data potentially suggest occupancy of normal B cell developmental niches by leukemia resulting in block in normal B cell development. Further supporting this hypothesis, we find significant reduction in early progression of ALL in aged (10–12 month old) mice known to have a deficiency in B cell developmental niches. We next explored whether specific factors that support normal B cell development can contribute to progression of precursor B cell leukemia. The normal B cell niche has only recently been characterized and the specific contribution of this niche to early ALL progression has not been extensively studied. Using a candidate approach, we examined the role of specific cytokines such as Interleukin-7 (IL-7) and thymic stromal lymphopoietin (TSLP) in early ALL progression. Our preB ALL line expresses high levels of IL-7Ralpha and low but detectable levels of TLSPR. In the presence of IL-7 (0.1 ng/ml) and TSLP (50 ng/ml) phosphSTAT5 is detectable indicating that these receptors are functional but that supraphysiologic levels of TSLP are required. Consistent with the importance of IL-7 in leukemia progression, preliminary data demonstrates reduced lethality of pr-B cell ALL in IL-7 deficient mice. Overexpression of TSLP receptor (TSLPR) has been associated with high rates of relapse and poor overall survival in precursor B cell ALL. We are currently generating a TSLPR overepressing preBALL line to determine the effect on early ALL progression and are using GFP-expressing preB ALL cells to identify the initial location of preB ALL occupancy in the bone marrow. In conclusion, or model of early ALL progression provides insight into the role of the bone marrow microenvironment in early ALL progression and provides an opportunity to examine how these microenvironmental factors contribute to therapeutic resistance. Given recent advances in immunotherapy for hematologic malignancies, the ability to study this in an immunocompetent host will be critical. Disclosures: No relevant conflicts of interest to declare.

Immunoglobulin Heavy Chain (IgH) Knockout Inhibits Proliferation of Pre-BCR+ B-Cell Acute Lymphoblastic Leukemia (B-ALL) Via a FOXO1 and MYC Dependent Mechanism

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 287-287
Author(s):  
Stefan Koehrer ◽  
Ondrej Havranek ◽  
R Eric Davis ◽  
Felix Seyfried ◽  
Greg Coffey ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Total Protein ◽  
Lymphoblastic Leukemia ◽  
Cell Development ◽  
B Cell Development ◽  
Protein Levels ◽  
Bcr Signaling ◽  
Cell Acute Lymphoblastic Leukemia

Abstract A pivotal step during B-cell development is the expression of the precursor B-cell receptor (pre-BCR) by pre-B lymphocytes (cyto-Igµ+, surface-IgM-). The pre-BCR represents an immature form of the BCR and consists of two immunoglobulin heavy chains (IgH), two surrogate light chains (SLC) and the signal transducing adapter proteins Igα and Igβ. A functional pre-BCR drives proliferation of pre-B-cells, ensuring their further differentiation into mature B-cells. By immunophenotype, ~20% of B-cell acute lymphoblastic leukemia (B-ALL) cases originate from the pre-B-cell stage (pre-B-ALL) of lymphocyte development and might therefore also express the pre-BCR. In view of the importance of pre-BCR signaling for normal pre-B-cell development, we hypothesize that it is exploited by pre-B-ALL for malignant growth and proliferation. A hallmark of active pre-BCR signaling is the continuous internalization of pre-BCRs, resulting in low pre-BCR surface expression. Using this phenotype of active pre-BCR signaling (low pre-BCR expression and high phosphorylation of the pre-BCR associated kinases LYN and SYK), we identified pre-BCR+ ALL cell lines (RCH-ACV, SMS-SB and Nalm6) and xenograft expanded patient samples. To study the role of the pre-BCR in these cells, we rendered RCH-ACV and SMS-SB pre-BCR null by using CRISPR/CAS9 gene editing with guide RNAs specific for the hypervariable region (recombined V, D, and J segments) of their expressed IgH allele. As identified by flow cytometry for the pre-BCR, deficient RCH-ACV and SMS-SB cells exhibited reduced viability and impaired proliferation when compared to their pre-BCR+ controls (Figure 1). Pre-BCR- cells showed reduced baseline phosphorylation of CD19, VAV1 and AKT. Interestingly, BTK and ERK phosphorylation were not affected. These results provide evidence for the dependency of pre-BCR+ ALL on pre-BCR signaling and suggest selective involvement of the PI3K-AKT pathway. We also investigated the effects of pharmacological pre-BCR inhibition by treating pre-BCR+ and pre-BCR- ALL cell lines and xenograft expanded primary patient samples with PRT318, a small-molecule inhibitor of spleen tyrosine kinase (SYK). In pre-BCR+ ALL PRT318 blocked cell proliferation and selectively inhibited AKT phosphorylation, thus mimicking the effects of IgH knockout. Pre-BCR- ALL cells were resistant to PRT318. Key effectors of the pre-BCR during normal B-cell development are FOXO transcription factors. In line with this, we found reduced FOXO1 phosphorylation and increased FOXO1 total protein levels after IgH knockout as well as after treatment with PRT318. This was accompanied by an increase in the FOXO1 transcriptional targets p27 and BLNK, suggesting increased FOXO1 transcriptional activity in response to the inhibition of pre-BCR signaling. To study the contribution of FOXO1 to the effects of IgH knockout and SYK inhibition more thoroughly, we expressed constitutively active FOXO1 (FOXO1-3A) in the pre-BCR+ ALL cell line RCH-ACV and consequently assessed its effects on cell proliferation and protein expression. Similar to IgH knockout and PRT318, FOXO1-3A reduced cell proliferation and increased p27 and BLNK protein levels, confirming FOXO1 as an important downstream target of pre-BCR signaling in B-ALL. To identify additional effectors of the pre-BCR in B-ALL we performed gene expression profiling (GEP) to compare pre-BCR+ and pre-BCR- cells of RCH-ACV and SMS-SB. Gene set enrichment analysis (GSEA) showed that IgH knockout resulted in significant enrichment for gene sets associated with down-modulation of MYC activity. This was confirmed by Western blot analysis of MYC total protein levels, and consistent with the finding of reduced MYC protein in PRT318-treated and FOXO1-3A-expressing pre-BCR+ cells, all indicating that pre-BCR signaling modulates MYC activity through a mechanism involving SYK and FOXO1. In conclusion, we provide evidence for the dependence of certain B-ALL subgroups on pre-BCR signaling. According to our data this is mainly due to pre-BCR-induced inactivation of FOXO1 and the subsequent deregulation of MYC. Importantly, pharmacological inhibition of pre-BCR signaling with the SYK inhibitor PRT318 completely reversed these effects, therefore providing a rationale for the use of SYK inhibitors in pre-BCR+ subgroups of B-ALL. Figure 1: Figure 1 Figure 1. Disclosures Coffey: Portola Pharmaceuticals: Employment, Equity Ownership.

scholarly journals Ebf1 or Pax5 haploinsufficiency synergizes with STAT5 activation to initiate acute lymphoblastic leukemia

2011 ◽  
Vol 208 (6) ◽  
pp. 1135-1149 ◽  
Author(s):  
Lynn M. Heltemes-Harris ◽  
Mark J.L. Willette ◽  
Laura B. Ramsey ◽  
Yi Hua Qiu ◽  
E. Shannon Neeley ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Target Genes ◽  
Lymphoblastic Leukemia ◽  
Active Form ◽  
Cell Development ◽  
B Cell Development ◽  
Leukemic Cells ◽  
Small Perturbations ◽  
Potential Tumor Suppressor

As STAT5 is critical for the differentiation, proliferation, and survival of progenitor B cells, this transcription factor may play a role in acute lymphoblastic leukemia (ALL). Here, we show increased expression of activated signal transducer and activator of transcription 5 (STAT5), which is correlated with poor prognosis, in ALL patient cells. Mutations in EBF1 and PAX5, genes critical for B cell development have also been identified in human ALL. To determine whether mutations in Ebf1 or Pax5 synergize with STAT5 activation to induce ALL, we crossed mice expressing a constitutively active form of STAT5 (Stat5b-CA) with mice heterozygous for Ebf1 or Pax5. Haploinsufficiency of either Pax5 or Ebf1 synergized with Stat5b-CA to rapidly induce ALL in 100% of the mice. The leukemic cells displayed reduced expression of both Pax5 and Ebf1, but this had little effect on most EBF1 or PAX5 target genes. Only a subset of target genes was deregulated; this subset included a large percentage of potential tumor suppressor genes and oncogenes. Further, most of these genes appear to be jointly regulated by both EBF1 and PAX5. Our findings suggest a model whereby small perturbations in a self-reinforcing network of transcription factors critical for B cell development, specifically PAX5 and EBF1, cooperate with STAT5 activation to initiate ALL.

Fates of human B-cell precursors

Blood ◽  
2000 ◽  
Vol 96 (1) ◽  
pp. 9-23 ◽  
Author(s):  
Tucker W. LeBien
Keyword(s):  
Bone Marrow ◽  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Lymphoblastic Leukemia ◽  
Cell Receptor ◽  
Cell Development ◽  
B Cell Development ◽  
B Lineage ◽  
Human B Cell ◽  
B Lineage Cells

Abstract Development of mammalian B-lineage cells is characterized by progression through a series of checkpoints defined primarily by rearrangement and expression of immunoglobulin genes. Progression through these checkpoints is also influenced by stromal cells in the microenvironment of the primary tissues wherein B-cell development occurs, ie, fetal liver and bone marrow and adult bone marrow. This review focuses on the developmental biology of human bone marrow B-lineage cells, including perturbations that contribute to the origin and evolution of B-lineage acute lymphoblastic leukemia and primary immunodeficiency diseases characterized by agammaglobulinemia. Recently described in vitro and in vivo models that support development and expansion of human B-lineage cells through multiple checkpoints provide new tools for identifying the bone marrow stromal cell–derived molecules necessary for survival and proliferation. Mutations in genes encoding subunits of the pre-B cell receptor and molecules involved in pre-B cell receptor signaling culminate in X-linked and non–X-linked agammaglobulinemia. A cardinal feature of these immunodeficiencies is an apparent apoptotic sensitivity of B-lineage cells at the pro-B to pre-B transition. On the other end of the spectrum is the apoptotic resistance that accompanies the development of B-lineage acute lymphoblastic leukemia, potentially a reflection of genetic abnormalities that subvert normal apoptotic programs. The triad of laboratory models that mimic the bone marrow microenvironment, immunodeficiency diseases with specific defects in B-cell development, and B-lineage acute lymphoblastic leukemia can now be integrated to deepen our understanding of human B-cell development.

Identification of Cmtm Family Proteins As Tumor Suppressor and Membrane Regulator in B Cell Precursor Acute Lymphoblastic Leukemia

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3582-3582
Author(s):  
Jeyanthy Eswaran ◽  
Paul Sinclair ◽  
Sirintra Nakjang ◽  
Christine J. Harrison
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Tumor Suppressor ◽  
B Cell ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Cell Development ◽  
B Cell Development ◽  
Chromosome 21 ◽  
Cell Precursor ◽  
Physiological Functions

Abstract Acute lymphoblastic leukemia (ALL) is characterized by the expansion of immature hematopoietic cells in the bone marrow and blood. It is the most common childhood malignancy and is one of the major causes of death in children. Treatment improvements have increased the cure rate to more than 80% for children and about 40% for adults. However, current chemotherapy causes acute and long-term toxicity. Hence, there is a compelling need to understand the development of ALL and identify key players that may be used in targeted therapy. The B-cell receptor (BCR) and its precursor, pre-BCR, control B cell development, which is arrested in ALL. This blockade occurs at the first quality control checkpoint of B-cell development; the pre BCR checkpoint. To enhance our understanding of B-cell precursor (BCP)-ALL specific membrane associated signaling, we have investigated the functions of the recently discovered Chemokine factor like Marvel like Trans Membrane proteins (CMTM) that interact with BCR in pre-BCR checkpoint. We have identified heterozygous focal deletions of CMTM family genes, specifically CMTM6, 7 and 8 in BCP-ALL, including the subtype with intrachromosomal amplification of chromosome 21 (iAMP21). Similar focal deletions were found in iAMP21 xenograft models after serial passage, indicating their possible link to survival advantage. Although CMTM family proteins were first described in 2003, little is known about their physiological functions. The loss of a small gene cluster at chromosome 3p22, including CMTM6 and 7 has been reported in several cancers, including esophageal squamous cell, nasopharyngeal and lung carcinomas, indicating their potential roles as tumor suppressor genes. Among the CMTM family members, CMTM3 and 7 were initially identified as interacting partners of B-cell receptors. To characterize the CMTM mediated macromolecular assemblage in BCP-ALL, immunoprecipitation (IP) studies were performed using CMTM7 antibody. Initially, the expression of CMTM7 and the sensitivity of the CMTM7 antibodies were tested using various BCP-ALL cell lines. Due to their positive expression levels, the pre-B697 and NALM6 cell lines were selected for the IP studies. When the CMTM7-mediated membrane protein complex was isolated using CMTM7 antibody, we determined that the well-established tumor suppressor, B-cell linker (BLNK), interacted with CMTM7 in pre-B697 and NALM6. CMTM7-interaction partners are being verified by mass spectrometry. Next, to identify possible physiological functions, we performed a phylogenetic analysis and discovered that the CMTM family genes were homologous to myelin and lymphocyte (MAL) proteins, tricellulins, plasmolipins and occludin families, which comprise the tetra-spanin trans-membrane domain known as MARVEL (MAL and related protein for vesicle trafficking and membrane linking). These proteins are associated with cell communication and intracellular transport. To investigate the molecular mechanism of action of CMTM6, 7 and 8 in BCP-ALL and B cell development, we cloned, expressed and purified all three members and preliminary functional studies in-vitro indicated that they formed oligomers. Taken together, these data identify a critical membrane regulator, CMTM7, which may function as a tumor suppressor, communicating signals from membrane to cytosolic components through BLNK signaling in BCP-ALL. Disclosures No relevant conflicts of interest to declare.

Fates of human B-cell precursors

Blood ◽  
2000 ◽  
Vol 96 (1) ◽  
pp. 9-23 ◽  
Author(s):  
Tucker W. LeBien
Keyword(s):  
Bone Marrow ◽  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Lymphoblastic Leukemia ◽  
Cell Receptor ◽  
Cell Development ◽  
B Cell Development ◽  
B Lineage ◽  
Human B Cell ◽  
B Lineage Cells

Development of mammalian B-lineage cells is characterized by progression through a series of checkpoints defined primarily by rearrangement and expression of immunoglobulin genes. Progression through these checkpoints is also influenced by stromal cells in the microenvironment of the primary tissues wherein B-cell development occurs, ie, fetal liver and bone marrow and adult bone marrow. This review focuses on the developmental biology of human bone marrow B-lineage cells, including perturbations that contribute to the origin and evolution of B-lineage acute lymphoblastic leukemia and primary immunodeficiency diseases characterized by agammaglobulinemia. Recently described in vitro and in vivo models that support development and expansion of human B-lineage cells through multiple checkpoints provide new tools for identifying the bone marrow stromal cell–derived molecules necessary for survival and proliferation. Mutations in genes encoding subunits of the pre-B cell receptor and molecules involved in pre-B cell receptor signaling culminate in X-linked and non–X-linked agammaglobulinemia. A cardinal feature of these immunodeficiencies is an apparent apoptotic sensitivity of B-lineage cells at the pro-B to pre-B transition. On the other end of the spectrum is the apoptotic resistance that accompanies the development of B-lineage acute lymphoblastic leukemia, potentially a reflection of genetic abnormalities that subvert normal apoptotic programs. The triad of laboratory models that mimic the bone marrow microenvironment, immunodeficiency diseases with specific defects in B-cell development, and B-lineage acute lymphoblastic leukemia can now be integrated to deepen our understanding of human B-cell development.

scholarly journals Transcriptional landscape of B cell precursor acute lymphoblastic leukemia based on an international study of 1,223 cases

2018 ◽  
Vol 115 (50) ◽  
pp. E11711-E11720 ◽  
Author(s):  
Jian-Feng Li ◽  
Yu-Ting Dai ◽  
Henrik Lilljebjörn ◽  
Shu-Hong Shen ◽  
Bo-Wen Cui ◽  
...  
Keyword(s):  
Gene Expression ◽  
Acute Lymphoblastic Leukemia ◽  
High Risk ◽  
B Cell ◽  
Rna Sequencing ◽  
Large Scale ◽  
Lymphoblastic Leukemia ◽  
International Study ◽  
Disease Classification ◽  
Cell Precursor

Most B cell precursor acute lymphoblastic leukemia (BCP ALL) can be classified into known major genetic subtypes, while a substantial proportion of BCP ALL remains poorly characterized in relation to its underlying genomic abnormalities. We therefore initiated a large-scale international study to reanalyze and delineate the transcriptome landscape of 1,223 BCP ALL cases using RNA sequencing. Fourteen BCP ALL gene expression subgroups (G1 to G14) were identified. Apart from extending eight previously described subgroups (G1 to G8 associated with MEF2D fusions, TCF3–PBX1 fusions, ETV6–RUNX1–positive/ETV6–RUNX1–like, DUX4 fusions, ZNF384 fusions, BCR–ABL1/Ph–like, high hyperdiploidy, and KMT2A fusions), we defined six additional gene expression subgroups: G9 was associated with both PAX5 and CRLF2 fusions; G10 and G11 with mutations in PAX5 (p.P80R) and IKZF1 (p.N159Y), respectively; G12 with IGH–CEBPE fusion and mutations in ZEB2 (p.H1038R); and G13 and G14 with TCF3/4–HLF and NUTM1 fusions, respectively. In pediatric BCP ALL, subgroups G2 to G5 and G7 (51 to 65/67 chromosomes) were associated with low-risk, G7 (with ≤50 chromosomes) and G9 were intermediate-risk, whereas G1, G6, and G8 were defined as high-risk subgroups. In adult BCP ALL, G1, G2, G6, and G8 were associated with high risk, while G4, G5, and G7 had relatively favorable outcomes. This large-scale transcriptome sequence analysis of BCP ALL revealed distinct molecular subgroups that reflect discrete pathways of BCP ALL, informing disease classification and prognostic stratification. The combined results strongly advocate that RNA sequencing be introduced into the clinical diagnostic workup of BCP ALL.

scholarly journals Suppression of B-cell development genes is key to glucocorticoid efficacy in treatment of acute lymphoblastic leukemia

Blood ◽  
2017 ◽  
Vol 129 (22) ◽  
pp. 3000-3008 ◽  
Author(s):  
Karina A. Kruth ◽  
Mimi Fang ◽  
Dawne N. Shelton ◽  
Ossama Abu-Halawa ◽  
Ryan Mahling ◽  
...  
Keyword(s):  
Cell Death ◽  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Lymphoblastic Leukemia ◽  
Cell Development ◽  
B Cell Development ◽  
Feedback Loops ◽  
Key Points ◽  
Cell Death Genes ◽  
Death Genes

Key PointsNext-generation functional genomics identifies B-cell development genes, pathways, and feedback loops that affect dex activity in B-ALL. Suppression of lymphoid-restricted PI3Kδ synergizes with dex in B-ALL by enhancing or restoring regulation of cell-death genes.

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