Pre-B cell receptor expression in B-lineage acute lymphoblastic leukemia: A report from the Children’s Oncology Group.

2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e19006-e19006
Author(s):  
Stuart S. Winter ◽  
Amanda McCaustland ◽  
No'eau Simeona ◽  
Andrew J. Carroll ◽  
Nyla A. Heerema ◽  
...  
Keyword(s):  
Gene Expression ◽  
B Cells ◽  
B Cell ◽  
Light Chain ◽  
Lymphoblastic Leukemia ◽  
Surface Expression ◽  
Oncology Group ◽  
Surrogate Light Chain ◽  
Cell Ablation ◽  
B Lineage

e19006 Background: The surface expression of mature B-cell markers have led to the development of immunotherapies against B-lineage lymphoblastic leukemia/lymphoma (B-ALL/B-LLy). Relapsing clones that have altered surface antigen expression are common means of treatment failure with immunotherapies. The elimination of the pan-B cell repertoire by current B-cell immunotherapies contributes to immune-compromise. A promising target is the pre-BCR surrogate light chain, comprised of the VpreB1 (CD179a) and Lamda5 (CD179b) subunits. Surrogate light chain is expressed on pro- and pre-B cells where it governs preBCR-mediated autonomous survival during B-cell maturation. Gene expression analyses have shown that CD179a is expressed in a sub-set of 10 to 15% of B-ALL cases. Because immunotherapies targeted to restricted stages of B-cell development may overcome the limitations of pan B-cell ablation, we tested the hypothesis that CD179a is more commonly expressed on B-lymphoblasts than previously thought. Methods: Utilizing an annotated set of 36 standard (AALL0331) and high-risk (AALL0232) B-ALL cases accrued to Children’s Oncology Group AALL03B1, we adapted the COG minimal residual disease (MRD) flow panel to include two additional PE- and FITC-conjugated mAbs against CD179a (Biolegend and i2Pharma). We assessed CD179a expression in 16 cases for which we had Day 28 end-induction samples, pre-selected to have ≥1% MRD, as determined by the COG Reference laboratories. Cases with ≥20% CD179a surface expression were determined to be positive for statistical comparisons. All analyses were performed on a 6-color Becton-Dickinson flow cytometer in a CLIA/CAP certified laboratory. Results: Thirty-four cases were arrested at the CD10-positive pre-B stage, and two cases at the CD10-negative pro-B stage. One or both mAbs showed that CD179a was present in ≥20% of the B-lymphoblast population, ranging from 20.2% to 90.6% for all 36 diagnostic samples. All cases expressed CD179a in the end-induction B-lymphoblast population. Compared to gene-expression based predictions, we found a significant difference between expected versus observed flow-based CD179a positivity (two-sided Fisher’s exact test, P< 0.001). We found that CD179a expression was observed in cases having E2A-PBX3, KMT2A, BCR-ABL1 and other re-arrangements that typify mixed phenotype acute leukemias (MPALs). Conclusions: Our results show that CD179a is commonly expressed in B-ALL, regardless of stage, NCI risk features, or molecular aberrations. Because the productively assembled preBCR mediates autonomous survival signaling in pro- and pre-B cells, it may also contribute to the mechanistic basis of MRD in B-ALL. Immunotherapies directed against the CD179a component of the preBCR may spare the immune-compromise that occurs with pan B-cell ablation, and prevent the emergence of therapy-resistant disease in B-ALL/B-LLy.

scholarly journals VpreB Surrogate Light Chain Expression in B-Lineage ALL: A Report from the Children's Oncology Group

2021 ◽  
Author(s):  
Stuart Sheldon Winter ◽  
Amanda McCaustland ◽  
Chunxu Qu ◽  
No'eau Simeona ◽  
Nyla A. Heerema ◽  
...  
Keyword(s):  
B Cell ◽  
Light Chain ◽  
Residual Disease ◽  
Lymphoblastic Leukemia ◽  
Cell Surface Markers ◽  
Becton Dickinson ◽  
Surrogate Light Chain ◽  
Developmental Arrest ◽  
Survival Signaling ◽  
B Lineage

Immunotherapies directed against B-cell surface markers have been a common developmental strategy to treat B-cell malignancies. The IgH surrogate light chain (SLC), comprised of the VpreB1 (CD179a) and Lamda5 (CD179b) subunits is expressed on pro- and pre-B cells where it governs preBCR-mediated autonomous survival signaling. We hypothesized that the pre-BCR might merit the development of targeted immunotherapies to decouple "autonomous" signaling in B-lineage acute lymphoblastic leukemia (B-ALL). We used the COG minimal residual disease (MRD) flow panel to assess pre-BCR expression in 36 primary patient samples accrued to COG standard and high-risk B-ALL studies through AALL03B1. We also assessed CD179a expression in 16 cases with Day 29 end-induction samples, pre-selected to have ≥1% MRD. All analyses were performed on a 6-color Becton-Dickinson flow cytometer in a CLIA/CAP-certified laboratory. Among 36 cases tested, thirty-two were at the pre-B and four were at the pro-B stages of developmental arrest. One or both mAbs showed that CD179a was present in ≥20% of the B-lymphoblast population. All cases expressed CD179a in the end-induction B-lymphoblast population. The CD179a component of the SLC is commonly expressed in B-ALL, regardless of genotype, stage of developmental arrest or NCI risk-status.

Cell surface expression of surrogate light chain (ΨL) in the absence of μ on human pro-B cell lines and normal pro-B cells

1996 ◽  
Vol 26 (9) ◽  
pp. 2172-2180 ◽  
Author(s):  
Eric Meffre ◽  
Michel Fougereau ◽  
Jean-Noël Argenson ◽  
Jean-Manuel Aubaniac ◽  
Claudine Schiff
Keyword(s):  
B Cells ◽  
Cell Surface ◽  
B Cell ◽  
Cell Lines ◽  
Light Chain ◽  
Surface Expression ◽  
Cell Surface Expression ◽  
Surrogate Light Chain

scholarly journals Pre-BCR Surrogate Light Chain Components VPREB1 and IGLL1 Function As Pre-BCR-Independent Tumor Suppressors in Acute Lymphoblastic Leukemia

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 570-570
Author(s):  
Kadriye Nehir Cosgun ◽  
Rudi W Hendriks ◽  
Ross A Dickins ◽  
Nora Heisterkamp ◽  
Markus Muschen
Keyword(s):  
B Cells ◽  
Transgenic Mice ◽  
B Cell ◽  
Light Chain ◽  
Tumor Suppressors ◽  
Function Analysis ◽  
Lymphoblastic Leukemia ◽  
Genetic Evidence ◽  
Surrogate Light Chain ◽  
Independent Functions

Abstract Background: IGLL1 and VPREB1 encode for the l5 and VpreB components, respectively, of the surrogate light chain (SLC) of the pre-B cell receptor (pre-BCR). During early B-cell development, immunoglobulin (Ig) heavy chains pairs with SLCs to form the pre-BCR, a central signaling unit that drives proliferation and survival. Accordingly, germline mutations of IGLL1 (Minegishi J Exp Med 1998) and VPREB1 (Conley Immunol Rev 2005) are associated with profound B-cell defects and agammaglobulinemia in humans. However, somatic deletions of VPREB1 gene are frequent lesions in B-ALL and occur in >10% of B-ALL cases (Mangum et al., Leukemia 2014; Geng et al., Cancer Cell 2015), the significance of which is not clear. Since VPREB1 deletions are typically present at the time of diagnosis and are rarely acquired as secondary lesions at the time of relapse (Kuster Blood 2011), we hypothesized that loss of VPREB1 represents an early and essential event in leukemogenesis. Experimental Approach and Results: For genetic gain and loss of function analysis of VPREB1 and IGLL1, we established leukemia models based on pre-B cells from Igll1-/- mice (Kitamura Cell 1992), and Vpreb1-Igll1 double-transgenic mice (Van Loo Immunity 2007). Loss of Igll1 completely abrogated SLC expression on the surface of pre-B cells. In contrast, VpreB1-Igll1 double-transgenic pre-B cells expressed constitutively higher surface levels of SLC as part of their pre-BCR as evidenced by flow cytometry. Compared to wildtype controls, Igll1-/- pre-B cells lacking the ability to express a functional SLCs were more readily transformed by BCR-ABL1 oncogene. However, pre-B cells of VpreB1-Igll1 transgenic mice, were not permissive to BCR-ABL1 mediated transformation. In agreement with these results, VpreB1-Igll1 double-transgenic pre-B cells were resistant transformation by BCR-ABL1 in vivo. BCR-ABL1-transgenic mice with enforced expression Vpreb1-Igll1 remained disease-free for more than nine months, whereas the vast majority of BCR-ABL1-transgenic mice downregulated pre-BCR surface expression and developed lethal B-ALL within 90 days of birth (n=34, P<0.0001). Compared to wildtype pre-B cells, double-transgenic expression of VpreB-Igll1 interfered with oncogenic BCR-ABL1 tyrosine kinase signaling and suppressed phosphorylation of Btk, Syk and Src kinases resulting in cell cycle arrest and reduced colony formation ability. To test whether SLC tumor suppressive function depends on pre-BCR activity, we studied BCR-ABL1-mediated transformation of VpreB1-Igll1 double-transgenic pre-B cells on a Rag1-deficient background. Rag1-/- pro-B cells lack the ability to rearrange Ig V, D and J-gene segments and cannot express a functional Ig mHC, the central structural element of the pre-BCR. Surprisingly, Rag1-/-VpreB1-Igll1 double-transgenic pro-B cells were also resistant to BCR-ABL1-mediated transformation. These findings provide genetic evidence that Vpreb1 and Igll1 exert tumor suppressive effect on B cells regardless of functional pre-BCR expression. Conclusion: The VpreB and Igll1 surrogate light chain components of the pre-BCR act as a tumor suppressors in pre-B ALL cells. Interestingly, the tumor suppressor function of both VpreB and Igll1 is independent from their SLC-role in pre-BCR signaling: Vpreb1- and Iggl1-mediated tumor suppression was effective, regardless of pre-BCR function. These findings provide genetic evidence that VpreB and Igll1 have pre-BCR- and SLC-independent functions that prevent malignant transformation and limit proliferation of normal pre-B cells. Our findings support the hypothesis that VPREB1 deletion represents an early event during clonal evolution towards pre-B ALL, facilitating subsequent steps of leukemic transformation. Disclosures No relevant conflicts of interest to declare.

The expression of Vpre-B/λ5 surrogate light chain in early bone marrow precursor B cells of normal and B cell-deficient mutant mice

Cell ◽  
1994 ◽  
Vol 77 (1) ◽  
pp. 133-143 ◽  
Author(s):  
Hajime Karasuyama ◽  
Antonius Rolink ◽  
Yoichi Shinkal ◽  
Faith Young ◽  
Frederick W. Alt ◽  
...  
Keyword(s):  
Bone Marrow ◽  
B Cells ◽  
B Cell ◽  
Light Chain ◽  
Mutant Mice ◽  
Deficient Mutant ◽  
Surrogate Light Chain ◽  
Bone Marrow Precursor ◽  
Precursor B Cells

scholarly journals Fate of surrogate light chains in B lineage cells.

1996 ◽  
Vol 183 (2) ◽  
pp. 421-429 ◽  
Author(s):  
K Lassoued ◽  
H Illges ◽  
K Benlagha ◽  
M D Cooper
Keyword(s):  
B Cells ◽  
Cell Surface ◽  
Light Chain ◽  
Light Chains ◽  
Receptor Complex ◽  
Surrogate Light Chain ◽  
Heavy Chains ◽  
Receptor Component ◽  
B Lineage ◽  
Receptor Assembly

Biosynthesis of the immunoglobulin (Ig) receptor components and their assembly were examined in cell lines representative of early stages in human B lineage development. In pro-B cells, the nascent surrogate light chain proteins form a complex that transiently associates in the endoplasmic reticulum with a spectrum of unidentified proteins (40, 60, and 98 kD) and Bip, a heat shock protein family member. Lacking companion heavy chains, the surrogate light chains in pro-B cells do not associate with either the Ig(alpha) or Ig(beta) signal transduction units, undergo rapid degradation, and fail to reach the pro-B cell surface. In pre-B cells, by contrast, a significant portion of the surrogate light chain proteins associate with mu heavy chains, Ig(alpha), and Ig(beta) to form a stable receptor complex with a relatively long half-life. Early in this assembly process, Bip/GRP78, calnexin, GRP94, and a protein of approximately 17 kD differentially bind to the nascent mu heavy chains. The 17-kD intermediate is gradually replaced by the surrogate light chain protein complex, and the Ig(alpha) and Ig(beta) chains bind progressively to the mu heavy chains during the complex and relatively inefficient process of pre-B receptor assembly. The results suggest that, in humans, heavy chain association is essential for surrogate light chain survival and transport to the cell surface as an integral receptor component.

Characterization of lincRNA BALIR-6 in MLL rearranged B-lymphoblastic leukemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 3730-3730
Author(s):  
Norma Iris Rodriguez-Malave ◽  
Weihong Yan ◽  
Giuseppe Basso ◽  
Martina Pigazzi ◽  
Dinesh S. Rao
Keyword(s):  
Gene Expression ◽  
B Cells ◽  
B Cell ◽  
Cell Lines ◽  
Microarray Data ◽  
Conflicts Of Interest ◽  
Lymphoblastic Leukemia ◽  
Regulate Gene Expression ◽  
In Cis ◽  
Regulate Gene

Abstract A new class of non-coding RNA, known as long intergenic non-coding RNAs (lincRNAs), has only recently been described. These lincRNAs have been found to play a role in various molecular processes within the cell including gene regulation, acting as sinks for microRNAs, and regulating splicing, implicating them in development and oncogenic processes. B lymphoblastic leukemia (B acute lymphoblastic leukemia; B-ALL), a malignancy of precursor B-cells, harbors mutations and translocations that result in a dysregulated gene expression. Interestingly, dysregulated expression of lincRNAs has been found in various cancers, but has not yet been described in B-ALL. Recently, we completed a gene expression profiling study in human B-ALL samples, which showed differential lincRNA expression in samples with particular cytogenetic abnormalities. This led us to hypothesize that lincRNAs may be related to disease pathogenesis. Here, we describe a promising lincRNA from our microarray data designated B-ALL associated long intergenic RNA 6 (BALIR-6). Expression of BALIR-6 is highest in patient samples carrying the MLL rearrangement (n=16; when compared to patients with TEL-AML1-translocated, n=39; E2A-PBX1-translocated, n=8; BCR-ABL-translocated, n=3; and cytogenetically normal cases, n=56; 1-way ANOVA p<0.0001) and showed significant variance in the expression level based on the immunophenotype (1-way ANOVA p=0.0004). BALIR-6 is located on chromosome 3p24.3 in humans, and exists in a syntenic gene block in with neighboring genes SATB1 and TBC1D5, and is conserved in mammals. Rapid Amplification of cDNA Ends (RACE) uncovered multiple transcript isoforms; from these, three were cloned out and sequenced, corresponding to the genomic locus as predicted. In B-ALL cell lines, BALIR-6 expression was highest in RS411 cells, which carry the MLL rearrangement, when compared to other B-ALL cell lines. This suggests that the cell lines may show a similar expression pattern to human B-ALL samples. To study the functional role of BALIR-6 we utilized siRNA in a mmu-miR-155 expression cassette to knockdown the transcript. In RS411 cells we observed a reduction in proliferation by MTS assay. Additionally, we observed an increase Sub-G0 cells and a decrease in G2-M phase cells by propidium iodide staining, suggesting an increase in apoptosis. Conversely, overexpression of BALIR-6 in a mouse pre-B cell line (70Z/3), leads to an increase in proliferation. Interestingly, during normal B cell development, BALIR-6 is dynamically expressed, with high expression in pre-B cells and subsequent downregulation, suggesting that a normal role during development is being hijacked in patients with B-ALL. Mechanistically, a few recent studies have described that lincRNAs can regulate gene expression in cis. To explore whether BALIR 6 regulates surrounding genes in cis, we analyzed microarray data of MLL rearranged B-ALL samples, finding that expression of BALIR-6 correlates with expression of surrounding genes SATB1 and TBC1D5. Interestingly for SATB1, this correlation is also seen in human B cell developmental stages. Altering BALIR-6 expression by siRNA mediated knockdown or overexpression causes an effect on the expression of surrounding genes SATB1 and TBC1D5. Previous findings have shown that dysregulated SATB1 has been seen in a variety of malignancies, suggesting a mechanism for how BALIR-6 may produce the changes in cell growth and apoptosis described above. Altogether, these results identify a novel and interesting RNA transcript with the potential to regulate gene expression and pathogenesis in B-ALL with MLL rearrangement, suggesting novel diagnostic, prognostic, and therapeutic implications. Disclosures: No relevant conflicts of interest to declare.

scholarly journals In aged mice, low surrogate light chain promotes pro‐ B ‐cell apoptotic resistance, compromises the P re BCR checkpoint, and favors generation of autoreactive, phosphorylcholine‐specific B cells

Aging Cell ◽  
2015 ◽  
Vol 14 (3) ◽  
pp. 382-390 ◽  
Author(s):  
Michelle Ratliff ◽  
Sarah Alter ◽  
Kelly McAvoy ◽  
Daniela Frasca ◽  
Jacqueline A. Wright ◽  
...  
Keyword(s):  
B Cells ◽  
B Cell ◽  
Light Chain ◽  
Aged Mice ◽  
Surrogate Light Chain

Evidence for Non-Random Immunoglobulin VH Gene and Light Chain Isotype Usage in Follicular Non-Hodgkin’s Lymphoma.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2408-2408
Author(s):  
Christopher B. Yohn ◽  
Charles P. Van Beveren ◽  
Xi Y. Mu ◽  
Peter Shier ◽  
Gregg J. Silverman ◽  
...  
Keyword(s):  
Gene Expression ◽  
B Cells ◽  
B Cell ◽  
Light Chain ◽  
Light Chains ◽  
B Cell Malignancies ◽  
Gene Usage ◽  
Vh Gene ◽  
V Gene ◽  
Peripheral B Cells

Abstract Background: Antibody diversity is generated by recombination of individual immunoglobulin (Ig) gene segments and subsequent somatic diversification driven by antigen recognition. In the repertoire of expressed B cell receptors (BCR) among normal peripheral B cells, variable heavy (VH) gene segments are not equally represented. The ratio of kappa to lambda light chain usage is also skewed; the normal κ/λ is 1.5. Investigation of the BCR repertoire may provide clues to the genesis of B cell malignancies, as suggested in chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL). BCR V gene identification during the production of recombinant antibodies used in our ongoing PhII and PhIII FavId® (idiotype/KLH) immunotherapy studies has enabled us to analyze V gene usage from 475 B cell follicular lymphoma (FL) tissue samples. This study reports the results of VH gene and κ/λ gene expression in this FL sample collection. Methods: Ig heavy chain (HC) and light chain (LC) isotypes from B cell FL samples were identified by flow cytometry. VH and VL regions were sequenced from gene specific cDNA libraries prepared from these samples. VH gene usage and κ/λ ratios were compared to frequencies determined for normal peripheral B cells isolated from six healthy volunteers as well as published reports for normal peripheral B cells and other B cell malignancies. Results: Compared to VH gene family usage determined for normal B cells, VH3 usage is higher (68% vs. 42%), VH1 usage is lower (7.8% vs. 22%) and VH4 usage is equivalent (22% vs. 26%) in our cohort of FL patients while VH2, 5, 6 and 7 are infrequently used in both populations. Usage of the VH3 genes within FL derived sequences also depends upon isotype, in that this gene family is preferentially associated with the IgM HC isotype relative to IgG (76% and 57% respectively). Additionally, the combined usage of the specific genes VH3-23 and VH3-48 in our patient collection accounts for over 29% of all VH genes - compared to 9% among normal B cells. These VH gene usages also differ from reports of VH gene expression among CLL and MCL patients. With respect to LC usage, VH3 isolates are associated with a normal κ/λ ratio of 1.6 while VH4 gene isolates are preferentially associated with λ light chains with a κ/λ ratio of 0.9. Finally, FL B cells expressing the IgM HC isotype preferentially co-express κ light chains (κ/λ ratio of 2.4) while IgG expressing cells preferentially utilize λ chains (κ/λ ratio of 0.6). Conclusions: Non-random V gene and LC expression among patients with FL is noted. These distortions in Ig gene expression suggest that lymphomagenesis in FL may be associated with B cell stimulation by common antigens. A program to investigate the epitopes recognized by FL derived BCRs via binding of recombinant FL derived antibodies to protein arrays containing common auto-antigens is currently underway.

CD127 Expression Confers Enhanced Survival on Human B-Lineage Cells; Implications for the Role of IL-7 Signaling in Human B Lymphopoiesis.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1329-1329
Author(s):  
Sonja E. Johnson ◽  
J. Donald Capra ◽  
Tucker W. LeBien
Keyword(s):  
Gene Expression ◽  
B Cells ◽  
Cord Blood ◽  
B Cell ◽  
Immunofluorescent Staining ◽  
Segment Length ◽  
B Lineage ◽  
B Cell Precursors ◽  
Cd127 Expression ◽  
B Lineage Cells

Abstract The IL-7Rα chain (CD127) is expressed on some, but not all, CD19+/surface μ-B-lineage cells isolated from fetal and adult marrow, and umbilical cord blood, but the functional consequences of CD127 expression in early human B cell development during all stages of human life are unresolved. We have described a xenogeneic culture model for generating CD19+ B-lineage cells from CD34+ cord blood stem cells following a 4 wk co-culture on murine MS-5 stromal cells (Johnson SE et al., 2005 J Immunol.). The majority of these cells express a pro-B cell phenotype i.e., CD19+/CD10+/CD20lo/CD21−/CD22+/CD24+/pre-BCR-. Moreover, 1–4% express surface μ heavy chains (HC), and some express κ or λ light chains. We have also reported that 20–40% of CD19+ cells emerging in the xenogeneic culture express CD127, CD127+ cells are more blastic than CD127- cells, and development of CD19+ cells is substantially blocked in xenogeneic cultures treated with anti-murine IL-7 (Johnson SE, ibid). The goal of the present study was to further characterize the developmental potential and patterns of gene expression in CD19+/CD127+ and CD19+/CD127− cells that emerge in xenogeneic cultures. We hypothesized that CD127 expression defines a subset of CD19+ B cell precursors with heightened potential to become mature B-lymphocytes. CD19+/CD127+ and CD19+CD127− populations that emerged in 4 wk xenogeneic cultures were sorted to > 95% purity by FACS. Immunofluorescent staining showed that surface and intracellular μ HC positive cells were present in both sorted populations at frequencies of 3–4%. Using an RT-PCR-based sequencing approach, we analyzed approximately 100 IgM V region sequences from both CD19+/CD127+ and CD19+/CD127− FACS-purified populations. The results indicated that the sequences from both populations were: non-mutated and used VH4, D and J gene segments that were similar to what would be expected in a cord blood B cell repertoire, and exhibited no statistically significant difference in N segment length, CDR3 length, or CDR3 charges. These results suggest that the amplified sequences were likely derived from the 3–4% cytoplasmic μ HC+ pre-B cells present in both sorted populations. The immunofluorescent staining and VDJH rearrangement sequence results suggest that large CD19+/CD127+/cytoplasmic μ HC+ pre-B cells may differentiate into small CD19+/CD127−/cytoplasmic μ HC+ cells in the xenogeneic culture. This was further supported by showing that intra-tibial injection of FACS-purified CD19+/CD127+ and CD19+/CD127− cells into sub-lethally irradiated NOD-SCID mice led to the appearance of surface μ HC+ cells from both sorted populations. Western blotting of sorted CD19+/CD127+ and CD19+/CD127− cells showed the presence of Bcl-2, p-GSK3β (specifically p-Ser9, the residue phosphorylated by AKT) and pERK1/2 in CD19+/CD127+ cells, while these proteins/phosphoproteins were undetectable in CD19+/CD127− cells. By contrast, expression of the cell cycle inhibitor p27KIP1 was elevated in CD19+/CD127− cells compared to CD19+/CD127+ cells. Furthermore, FACS-purified CD19+/CD127+ cells survived longer than CD19+/CD127− cells when cultured in the absence of MS-5, and the survival of the former was enhanced by stimulation with IL-7. The collective results indicate that CD127 expression identifies a population of normal human CD19+ B cell precursors with a pattern of gene expression and survival/proliferation attributes consistent with a crucial role in the development of the B-lymphocyte arm of the human immune system.

Pediatric Acute Lymphoblastic Leukemia Outcome Predictor Genes OPAL1 and RANTES Modulate Transformation by the V-Abl Oncogene

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5318-5318
Author(s):  
Jason H. Rogers ◽  
Kristin S. Owens ◽  
Jake M. Vargas ◽  
Cheryl L. Willman ◽  
Robert Hromas ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bone Marrow ◽  
Acute Lymphoblastic Leukemia ◽  
B Cells ◽  
Lymph Nodes ◽  
B Cell ◽  
Drug Targets ◽  
Lymphoblastic Leukemia ◽  
Novel Drug ◽  
Novel Drug Targets

Abstract B-precursor acute lymphoblastic leukemia (ALL) is the most common cancer of childhood. While it represents a highly curable malignancy, a significant number of children still relapse or present with disease that is resistant to therapeutic intensification. With the increasing intensity of curative treatment, there is also an increased incidence of late effects that adversely affect the quality of life of survivors. Previously, a large scale microarray gene expression analysis was undertaken in order to identify genes predictive of outcome that could enhance risk classification, thereby identifying children who might be cured with less intensive therapy or those who fail current regimens and require novel therapies for cure. From analysis of 254 pediatric ALL samples registered to various COG clinical trials, gene expression classifiers were identified that are highly predictive of poor and favorable outcome in precursor B-cell ALL. The goal of this project is to study the biologic function and role in hematopoiesis and leukemogenesis of the genes predictive of outcome and to determine whether any of these genes may serve as novel drug targets. To this end, we have developed a system to examine the effect of these genes on the cancer-promoting activity of the v-Abl oncogene. We have established pre-B cell lines by infecting primary mouse bone marrow cells with a virus expressing v-Abl. These lines were then engineered to express two of the genes we identified that were associated with poor or good treatment outcomes, RANTES (CCL5) and OPAL1 respectively. Consistent with the association of RANTES expression with poor outcome, v-Abl/RANTES pre-B cells are more proliferative than v-Abl cells, and form larger colonies in methylcellulose cultures without added cytokines. OPAL1 had the opposite effect on pre-B cell growth. V-Abl pre-B cells expressing OPAL1 were less proliferative and generated fewer colonies in methylcellulose cultures. To determine whether RANTES made the v-Abl pre-B cells more leukemic, we transplanted v-Abl or v-Abl/RANTES pre-B cells into syngeneic mice. Mice were noticeably ill 30 days post-transplant. Mice injected with v-Abl/RANTES cells had enlarged lymph nodes and increased numbers of white cells in their peripheral blood. The percentage of pre-B cells in the bone marrow, lymph nodes and spleen was higher in v-Abl/RANTES transplanted mice compared to v-Abl transplanted mice. Currently our data demonstrates that the outcome genes are playing a mechanistic role in the susceptibility of leukemic cells to therapy, and are not merely epiphenomenon. This suggests that the products of these genes and their associated pathways may be novel drug targets. Such targeted therapy has the potential of being less toxic than current nonspecific treatment regimens.

Sign in / Sign up

Export Citation Format

Share Document