scholarly journals PLZF and its fusion proteins are pomalidomide-dependent CRBN neosubstrates

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Nobuyuki Shimizu ◽  
Tomoko Asatsuma-Okumura ◽  
Junichi Yamamoto ◽  
Yuki Yamaguchi ◽  
Hiroshi Handa ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Fusion Proteins ◽  
Lymphoblastic Leukemia ◽  
Leukemic Cells ◽  
Immunomodulatory Agents ◽  
Mantle Cell ◽  
Potential Therapeutic Role ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Related Compounds

AbstractPomalidomide and lenalidomide are immunomodulatory agents that were derived from thalidomide. Cereblon (CRBN) is a common direct target of thalidomide and related compounds and works as a Cullin Ring 4 E3 ubiquitin ligase (CRL4) with DDB1, CUL4, and ROC1. The substrate specificity of CRL4CRBN is modulated by thalidomide-related compounds. While lenalidomide is approved for the treatment of several diseases including multiple myeloma, 5q- syndrome, mantle cell lymphoma, and follicular lymphoma, pomalidomide is approved only for the treatment of lenalidomide-resistant multiple myeloma. Here we show that PLZF/ZBTB16 and its fusion proteins are pomalidomide-dependent neosubstrates of CRL4CRBN. PLZF joins to RARα or potentially other partner genes, and the translocation causes leukemias, such as acute promyelocytic leukemia and T-cell acute lymphoblastic leukemia. We demonstrate that pomalidomide treatment induces PLZF-RARα degradation, resulting in antiproliferation of leukemic cells expressing PLZF-RARα. This study highlights a potential therapeutic role of pomalidomide as a degrader of leukemogenic fusion proteins.

A Critical Role of Blockade of Cell Differentiation in BCR-ABL-Induced B-Cell Acute Lymphoblastic Leukemia (B-ALL): Basis for Superb Therapeutic Effect on B-ALL in Mice by Promotion of Pro-B Leukemic Cell Differentiation and Treatment with Imatinib.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 844-844
Author(s):  
Yiguo Hu ◽  
Linghong Kong ◽  
Kevin Staples ◽  
Kevin Mills ◽  
John G. Monroe ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Myeloid Leukemia ◽  
Lymphoblastic Leukemia ◽  
Leukemic Cell ◽  
Leukemic Cells ◽  
B Cell Differentiation ◽  
Cell Acute Lymphoblastic Leukemia

Abstract The BCR-ABL oncogene induces human Philadelphia-positive (Ph+) B-cell acute lymphoblastic leukemia (B-ALL) and chronic myeloid leukemia (CML) that advances to acute phase of CML called blast crisis. In this acute phase, CML patients can develop either B-ALL or acute myeloid leukemia. In B-ALL, differentiation of leukemic cells are blocked at pro-/pre-B stage, and the underlying mechanism is unknown. We hypothesize that this blockade of B-cell differentiation may be important for the development of B-ALL induced by BCR-ABL, and if so, promotion of B-leukemic cell differentiation would create a novel therapeutic strategy for B-ALL. To test this hypothesis, we first compared the percentages of IgM+ B-leukemic cells in BALB/c and C57BL/6 (B6) mice with BCR-ABL-induced B-ALL, because we have previously found that B-ALL develops more quickly in BALB/c mice than in B6 mice (Li et al, J. Exp. Med.189:1399–1412, 1999). We expressed BCR-ABL in bone marrow (BM) using retroviral transduction and transplantation in these two different strains of inbred mice to induce B-ALL. There were significantly more peripheral blood B220+ B cells in BALB/c B-ALL mice than those in B6 mice, correlating to faster B-ALL in BALB/c mice than in B6 mice. Among these B220+ cells, IgM+ cells were much less in BALB/c mice than in B6 mice. We also compared rearrangement of the B cell antigen receptor (BCR) heavy chains (m chains) between BALB/c and B6 backgrounds using BCR-ABL-expressing pro-B cell lines isolated from the B-ALL mice. Normal m chains rearrangement was found in B6 leukemic cells, but not in BALB/c leukemic cells. These results indicate that more differentiated B-leukemic cells are associated with less aggressive disease. To further demonstrate the role of blockade of B-cell differentiation in B-ALL development, we induced B-leukemic cell differentiation by co-expression of BCR-ABL and intact immunoregulatory tyrosine activation motifs (ITAM) contained in immunoglobulin (Ig)_/Igß complexes in BM cells of B-ALL mice, comparing to expression of BCR-ABL alone. We treated these mice with imatinib (orally, 100 mg/kg, twice a day). The treated mice with B-ALL induced by co-expression of BCR-ABL and ITAM lived three-week longer than those with B-ALL induced by BCR-ABL only, with some mice in long-term remission. Prolonged survival was associated with 50% increased B220+/IgM+ B-leukemic cells in peripheral blood of the mice. Taken together, our results demonstrate that blockade of B-cell differentiation is critical for the development of B-ALL induced by BCR-ABL, and provide a rationale for combination therapy of B-ALL with imatinib and induction of leukemic cell differentiation.

RANK-RANKL Mediated Bone Destruction in B-Cell Acute Lymphoblastic Leukemia

Blood ◽  
2016 ◽  
Vol 128 (22) ◽  
pp. 908-908 ◽  
Author(s):  
Sujeetha A. Rajakumar ◽  
Eniko Papp ◽  
Ildiko Grandal ◽  
Daniele Merico ◽  
Careesa C. Liu ◽  
...  
Keyword(s):  
Bone Loss ◽  
B Cell ◽  
Lymphoblastic Leukemia ◽  
Leukemia Cell ◽  
Bone Destruction ◽  
Leukemic Cells ◽  
Leukemia Cells ◽  
Cell Acute Lymphoblastic Leukemia

Abstract Survival rates for pediatric B-Cell Acute Lymphoblastic Leukemia (B-ALL) have improved dramatically over the past 40 years approaching a current long-term survival rate of 85%. However childhood B-ALL patients continue to confront co-morbidities and their long-term consequences. For example, osteopenia and osteoporosis associated fractures are a common complication of pediatric leukemia at diagnosis, during treatment and in long-term B-ALL survivors. The STeroid-associated Osteoporosis in the Pediatric Population (STOPP) study reported that at ALL diagnosis, 16% of children and adolescents present with bone pain, vertebral compression and low vertebral Bone Mineral Density (BMD) scores, with the greatest incidence of vertebral fractures (VF) seen in the first year following diagnosis (J Clin Endocrinol Metab. 2015, 100:3408-17). Glucocorticoid treatment further elevated fracture risk in this population. These data underscore the need to identify molecular mechanism by which leukemic cells contribute to bone loss, and provide targeted therapies to limit these effects. Our laboratory previously showed that Rag2-/- p53-/- Prkdcscid/scid triple mutant (TM) and p53-/- Prkdcscid/scid double mutant (DM) mice develop spontaneous B-ALL, but only TM animals exhibit dissemination of leukemic blasts to the leptomeninges of the CNS, a poor prognosis feature observed in pediatric and adult ALL patients. We observed that TM leukemic mice also displayed fragile vertebral bones. Using comparative transcriptome analysis, we found that RANKL (Receptor Activator of the Nuclear factor-kB Ligand), a Tumor Necrosis Factor (TNF) superfamily member ligand and a key regulator of B cell and osteoclast differentiation, was expressed at greater levels in TM compared to the DM leukemia cells. RANKL binds to its receptor RANK, which is expressed in osteoclast precursor cells. RANK-RANKL interaction induces signaling in the osteoclast precursors and drives their differentiation into mature bone resorbing osteoclasts (Proc. Natl. Acad. Sci. 1999, 96:3540-3545). Upon adoptive leukemia cell transfer into immune deficient mice, RANKL+ TM but not DM cells caused decreased vertebral trabecular bone density in the recipients. Treatment with the recombinant RANKL antagonist protein Osteoprotegerin (OPG-Fc) inhibited the growth and dissemination of RANKL+TM leukemic cells and attenuated bone destruction in the recipient mice. These data suggested that TM mouse leukemia cells cause bone loss in the absence of glucocorticoid or other chemotherapy agents. We then examined the potential role of RANKL in osteoporosis associated with human B-ALL. RANKL mRNA was expressed by a majority of primary human adult and pediatric B-ALL. To determine whether primary patient B-ALL can cause bone loss, we transplanted RANKL+ human B-ALL samples of multiple cytogenetic high-risk subgroups (Complex, hypo-diploid and Mixed Lineage Leukemia (MLL) rearranged) into NOD.SCID.gC-/-(NSG) recipient mice. Micro-CT imaging and bone density measures in the xenotransplant recipients revealed extensive vertebral trabecular bone destruction. Immuno-histological analysis of the human B-ALL recipient mice demonstrated extensive osteoporotic damage of the long bones and marked RANKL protein expression in the long bones of mice harboring extensive human B-ALL cell burden compared to NSG control mice. To determine whether RANKL-RANK interaction was required for the B-ALL mediated bone destruction, cohorts of NSG mice engrafted with human B-ALL were treated with recombinant OPG-Fc compared to a matched Fc control protein. OPG-Fc treatment did not attenuate leukemia cell expansion and bone marrow burden, but despite bulky disease, the treatment conferred robust protection from bone destruction suggesting that RANKL was a critical mediator of this clinical complication. Our data demonstrate a central role of the RANK-RANKL axis in B-ALL-mediated bone disease and identify an actionable therapeutic target to reduce acute and long-term morbidity. Denosumab, an anti-RANKL antibody has been approved for the treatment of bone metastasis by solid tumors and for post-menopausal osteoporosis. Our pre-clinical studies suggest that Denosumab and other agents that inhibit the RANK-RANKL pathway may be efficacious in patients with B-ALL associated bone degeneration. Disclosures No relevant conflicts of interest to declare.

scholarly journals Notch1 inhibition targets the leukemia-initiating cells in a Tal1/Lmo2 mouse model of T-ALL

Blood ◽  
2011 ◽  
Vol 118 (6) ◽  
pp. 1579-1590 ◽  
Author(s):  
Jessica Tatarek ◽  
Kathleen Cullion ◽  
Todd Ashworth ◽  
Rachel Gerstein ◽  
Jon C. Aster ◽  
...  
Keyword(s):  
Mouse Model ◽  
Lymphoblastic Leukemia ◽  
Rapid Development ◽  
Leukemic Cells ◽  
Double Negative ◽  
Secretase Inhibitor ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Extended Survival ◽  
Inhibitor Treatment

Abstract T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive malignancy largely caused by aberrant activation of the TAL1/SCL, LMO1/2, and NOTCH1 oncogenes. Approximately 30% of T-ALL patients relapse, and evidence is emerging that relapse may result from a failure to eliminate leukemia-initiating cells (LICs). Thymic expression of the Tal1 and Lmo2 oncogenes in mice results in rapid development of T-ALL; and similar to T-ALL patients, more than half the leukemic mice develop spontaneous mutations in Notch1. Using this mouse model, we demonstrate that mouse T-ALLs are immunophenotypically and functionally heterogeneous with approximately 1 of 10 000 leukemic cells capable of initiating disease on transplantation. Our preleukemic studies reveal expansion of Notch-active double-negative thymic progenitors, and we find the leukemic DN3 population enriched in disease potential. To examine the role of Notch1 in LIC function, we measured LIC activity in leukemic mice treated with vehicle or with a γ-secretase inhibitor. In 4 of 5 leukemias examined, Notch inhibition significantly reduced or eliminated LICs and extended survival. Remarkably, in 2 mice, γ-secretase inhibitor treatment reduced LIC frequency below the limits of detection of this assay, and all transplanted mice failed to develop disease. These data support the continued development of Notch1 therapeutics as antileukemia agents.

scholarly journals Overcoming NOTCH1-Driven Chemoresistance in T-Cell Acute Lymphoblastic Leukemia Via Metabolic Intervention with Oxphos Inhibitor

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 18-20
Author(s):  
Natalia Baran ◽  
Alessia Lodi ◽  
Yogesh Dhungana ◽  
Shannon RENEE Sweeney ◽  
Pandey Renu ◽  
...  
Keyword(s):  
Board Of Directors ◽  
Research Funding ◽  
Target Genes ◽  
Lymphoblastic Leukemia ◽  
Leukemic Cells ◽  
Advisory Committees ◽  
Educational Grant ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Advisory Role

The inferior cure rate of T-cell acute lymphoblastic leukemia (T-ALL) is associated with inherent drug resistance. The activating NOTCH1 gene mutations have been reported to cause chemoresistance at the stem cell level1. Direct NOTCH1 inhibition has failed in clinical trials due to a narrow therapeutic window but targeting key oncogenic and metabolic pathways downstream of mutated NOTCH1 may offer novel approaches. We previously reported that rapid transformation of thymocytes at the DN3 differentiation stage into preleukemic stem cells (pre-LSC) requires elevated Notch1 in addition to the presence of Scl/Lmo11. Notably, we showed that cellular metabolism of NOTCH1-mutated T-ALLs depends on Oxidative Phosphorylation (OxPhos) and that OxPhos inhibition using the complex I inhibitor IACS-010759 (OxPhos-i) is efficacious in NOTCH1-mutated T-ALL patient derived xenografts (PDXs)2. Here, we investigated the link between NOTCH1-mutated chemoresistance and OxPhos in pre-leukemic and leukemic cells, utilizing comprehensive molecular and functional assays. We hypothesized that chemotherapy aided by OxPhos-i overcomes chemoresistance, depletes LSCs and combats T-ALL. First, we analyzed the role of OxPhos in downstream Notch1 targets at the pre- and leukemic stage considering four stages of thymocyte differentiation (D1-D4), in a mouse model of human T-ALL1. Gene set enrichment analysis (GSEA) implicated increased expression of Notch1 target genes starting at DN1, and OxPhos target genes were the highest-ranked gene set at DN3. Next, activation of Notch1 by its ligand DL4 and inhibition of OxPhos reduced viability of pre-LSCs, indicating that ligand-dependent activation of Notch1 signaling upregulates the OxPhos pathway and sensitizes pre-LSCs to OxPhos-i. To clarify the role of Notch1 signaling, we examined the effect of IACS-010759 on pre-leukemic thymocytes harboring LMO1, SCL-LMO1, NOTCH1, LMO1-NOTCH1 and SCL-LMO1-NOTCH1 with and without DL4 stimulation. We found that in the absence of DL4, only thymocytes harboring the Notch1 oncogene responded to OxPhos-i, whereas all DL4-stimulated thymocytes responded regardless of Notch1 status (Fig. 1a). In addition, at the leukemic stage, we found elevation of the OxPhos pathway driven by oncogenic Notch1 when we compared transcriptomes of SCL-LMO1 induced T-ALL in the presence or absence of the NOTCH1 oncogene. In line with the murine T-ALL NOTCH1 model, we performed transcriptome analysis of two independent T-ALL patient cohorts prior to chemotherapy, COG TARGET ALL (n=263) and AALL1231 (n=75), comparing transcriptomes of NOTCH1-mutated vs NOTCH1-wt T-ALLs. We found co-segregation of NOTCH1 mutations with significant upregulation of OxPhos and TCA cycle genes and downregulation of apoptosis signaling. Aiming to reverse the NOTCH1-controlled anti-apoptotic program and chemoresistance, we next tested the combination of Vincristine, Dexamethasone and L-Asparaginase (VXL) with IACS-010759. When compared to vehicle, OxPhos-i or VXL alone, only the VXL-OxPhos-i treatment caused an energetic crisis indicated by decreased OCR and ECAR (Seahorse), which translated to a profound reduction of viability (CTG, flow cytometry) in T-ALL cell lines (n=9) and primary T-ALL samples (n=5). Additionally, the IACS-VXL combination in vivo resulted in pan-metabolic blockade, which caused metabolic shut-down and triggered early induction of apoptosis in leukemic cells in peripheral blood, spleen and bone marrow (Fig. 1b). Single cell Proteomic analysis (CyTOF) of spleen showed reduced expression of cell proliferation marker -ki67, c-myc, ERK and p38 proteins, and reduction in number of leukemic cells. Finally, this combination therapy resulted in reduced leukemia burden and extension of overall survival across all three aggressive NOTCH1-mutated T-ALL PDX models (p<0.0001) (Fig.1 c, d). In summary, we demonstrated that targeting OxPhos with IACS-010759 in combination with chemotherapy facilitates eradication of chemoresistant NOTCH1-driven T-ALL through direct targeting of the key metabolic regulators of OxPhos conferred by mutant NOTCH1 in T-ALL. Clinical trials rewiring metabolism by incorporation of OxPhos-i to standard-of-care therapy in patients with NOTCH1-mutated T-ALL are warranted to improve patients' outcomes. Disclosures Jabbour: Pfizer: Other: Advisory role, Research Funding; Genentech: Other: Advisory role, Research Funding; BMS: Other: Advisory role, Research Funding; Takeda: Other: Advisory role, Research Funding; Amgen: Other: Advisory role, Research Funding; Adaptive Biotechnologies: Other: Advisory role, Research Funding; AbbVie: Other: Advisory role, Research Funding. Teachey:Sobi: Consultancy; Amgen: Consultancy; Janssen: Consultancy; La Roche: Consultancy. Rezvani:Takeda: Other: Licensing agreement; GemoAb: Membership on an entity's Board of Directors or advisory committees; Adicet Bio: Membership on an entity's Board of Directors or advisory committees; Virogen: Membership on an entity's Board of Directors or advisory committees; Pharmacyclics: Other: Educational grant; Affimed: Other: Educational grant; Formula Pharma: Membership on an entity's Board of Directors or advisory committees. Andreeff:Daiichi-Sankyo; Jazz Pharmaceuticals; Celgene; Amgen; AstraZeneca; 6 Dimensions Capital: Consultancy; Daiichi-Sankyo; Breast Cancer Research Foundation; CPRIT; NIH/NCI; Amgen; AstraZeneca: Research Funding; Centre for Drug Research & Development; Cancer UK; NCI-CTEP; German Research Council; Leukemia Lymphoma Foundation (LLS); NCI-RDCRN (Rare Disease Clin Network); CLL Founcdation; BioLineRx; SentiBio; Aptose Biosciences, Inc: Membership on an entity's Board of Directors or advisory committees; Amgen: Research Funding. Lorenzi:Precision Pathways: Consultancy. Konopleva:Calithera: Research Funding; Kisoji: Consultancy; AbbVie: Consultancy, Research Funding; Sanofi: Research Funding; Genentech: Consultancy, Research Funding; F. Hoffmann La-Roche: Consultancy, Research Funding; Cellectis: Research Funding; Rafael Pharmaceutical: Research Funding; Eli Lilly: Research Funding; Reata Pharmaceutical Inc.;: Patents & Royalties: patents and royalties with patent US 7,795,305 B2 on CDDO-compounds and combination therapies, licensed to Reata Pharmaceutical; Agios: Research Funding; AstraZeneca: Research Funding; Ablynx: Research Funding; Forty-Seven: Consultancy, Research Funding; Amgen: Consultancy; Stemline Therapeutics: Consultancy, Research Funding; Ascentage: Research Funding.

scholarly journals The Bone Marrow Niche in B-Cell Acute Lymphoblastic Leukemia: The Role of Microenvironment from Pre-Leukemia to Overt Leukemia

2021 ◽  
Vol 22 (9) ◽  
pp. 4426
Author(s):  
Erica Dander ◽  
Chiara Palmi ◽  
Giovanna D’Amico ◽  
Giovanni Cazzaniga
Keyword(s):  
Bone Marrow ◽  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Lymphoblastic Leukemia ◽  
Leukemic Cell ◽  
Leukemic Cells ◽  
Bone Marrow Niche ◽  
Disease Manifestation ◽  
Cell Acute Lymphoblastic Leukemia

Genetic lesions predisposing to pediatric B-cell acute lymphoblastic leukemia (B-ALL) arise in utero, generating a clinically silent pre-leukemic phase. We here reviewed the role of the surrounding bone marrow (BM) microenvironment in the persistence and transformation of pre-leukemic clones into fully leukemic cells. In this context, inflammation has been highlighted as a crucial microenvironmental stimulus able to promote genetic instability, leading to the disease manifestation. Moreover, we focused on the cross-talk between the bulk of leukemic cells with the surrounding microenvironment, which creates a “corrupted” BM malignant niche, unfavorable for healthy hematopoietic precursors. In detail, several cell subsets, including stromal, endothelial cells, osteoblasts and immune cells, composing the peculiar leukemic niche, can actively interact with B-ALL blasts. Through deregulated molecular pathways they are able to influence leukemia development, survival, chemoresistance, migratory and invasive properties. The concept that the pre-leukemic and leukemic cell survival and evolution are strictly dependent both on genetic lesions and on the external signals coming from the microenvironment paves the way to a new idea of dual targeting therapeutic strategy.

scholarly journals DNA Methylation in T-Cell Acute Lymphoblastic Leukemia: In Search for Clinical and Biological Meaning

2021 ◽  
Vol 22 (3) ◽  
pp. 1388
Author(s):  
Natalia Maćkowska ◽  
Monika Drobna-Śledzińska ◽  
Michał Witt ◽  
Małgorzata Dawidowska
Keyword(s):  
Dna Methylation ◽  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Epigenetic Modification ◽  
Lymphoblastic Leukemia ◽  
Leukemic Cells ◽  
Global Methylation ◽  
Current State ◽  
History Of ◽  
Cell Acute Lymphoblastic Leukemia

Distinct DNA methylation signatures, related to different prognosis, have been observed across many cancers, including T-cell acute lymphoblastic leukemia (T-ALL), an aggressive hematological neoplasm. By global methylation analysis, two major phenotypes might be observed in T-ALL: hypermethylation related to better outcome and hypomethylation, which is a candidate marker of poor prognosis. Moreover, DNA methylation holds more than a clinical meaning. It reflects the replicative history of leukemic cells and most likely different mechanisms underlying leukemia development in these T-ALL subtypes. The elucidation of the mechanisms and aberrations specific to (epi-)genomic subtypes might pave the way towards predictive diagnostics and precision medicine in T-ALL. We present the current state of knowledge on the role of DNA methylation in T-ALL. We describe the involvement of DNA methylation in normal hematopoiesis and T-cell development, focusing on epigenetic aberrations contributing to this leukemia. We further review the research investigating distinct methylation phenotypes in T-ALL, related to different outcomes, pointing to the most recent research aimed to unravel the biological mechanisms behind differential methylation. We highlight how technological advancements facilitated broadening the perspective of the investigation into DNA methylation and how this has changed our understanding of the roles of this epigenetic modification in T-ALL.

A novel PAX5-ELN fusion protein identified in B-cell acute lymphoblastic leukemia acts as a dominant negative on wild-type PAX5

Blood ◽  
2006 ◽  
Vol 109 (8) ◽  
pp. 3417-3423 ◽  
Author(s):  
Marina Bousquet ◽  
Cyril Broccardo ◽  
Cathy Quelen ◽  
Fabienne Meggetto ◽  
Emilienne Kuhlein ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
B Cell ◽  
Target Genes ◽  
Lymphoblastic Leukemia ◽  
Quantitative Polymerase Chain Reaction ◽  
Dominant Negative ◽  
Leukemic Cells ◽  
Dominant Negative Effect ◽  
Wild Type ◽  
Cell Acute Lymphoblastic Leukemia

Abstract We report a novel t(7;9)(q11;p13) translocation in 2 patients with B-cell acute lymphoblastic leukemia (B-ALL). By fluorescent in situ hybridization and 3′ rapid amplification of cDNA ends, we showed that the paired box domain of PAX5 was fused with the elastin (ELN) gene. After cloning the full-length cDNA of the chimeric gene, confocal microscopy of transfected NIH3T3 cells and Burkitt lymphoma cells (DG75) demonstrated that PAX5-ELN was localized in the nucleus. Chromatin immunoprecipitation clearly indicated that PAX5-ELN retained the capability to bind CD19 and BLK promoter sequences. To analyze the functions of the chimeric protein, HeLa cells were cotransfected with a luc-CD19 construct, pcDNA3-PAX5, and with increasing amounts of pcDNA3-PAX5-ELN. Thus, in vitro, PAX5-ELN was able to block CD19 transcription. Furthermore, real-time quantitative polymerase chain reaction (RQ-PCR) experiments showed that PAX5-ELN was able to affect the transcription of endogenous PAX5 target genes. Since PAX5 is essential for B-cell differentiation, this translocation may account for the blockage of leukemic cells at the pre–B-cell stage. The mechanism involved in this process appears to be, at least in part, through a dominant-negative effect of PAX5-ELN on the wild-type PAX5 in a setting ofPAX5 haploinsufficiency.

B-Cell Acute Lymphoblastic Leukemia Arising in Patients with a Preexisting Diagnosis of Multiple Myeloma Is a Novel Cancer with High Incidence of TP53 Mutations

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 20-20
Author(s):  
Monique Chavez ◽  
Erica Barnell ◽  
Malachi Griffith ◽  
Zachary Skidmore ◽  
Obi Griffith ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Acute Lymphoblastic Leukemia ◽  
B Cells ◽  
B Cell ◽  
Mechanism Of Action ◽  
Lymphoblastic Leukemia ◽  
Treatment Options ◽  
Hematopoietic Stem ◽  
Tp53 Mutations ◽  
Cell Acute Lymphoblastic Leukemia

Multiple Myeloma (MM) is a malignancy of plasma cells that affects over 30,000 Americans every year. Despite advances in the treatment of the disease, approximately 12,000 American patients will still die of MM in 2019. One of the mainstays of treatment for MM is the immunomodulatory and antiangiogenic drug lenalidomide; which is used in induction therapy, maintenance therapy and treatment of relapsed disease. Although not fully elucidated, lenalidomide's mechanism of action in MM involves the drug binding to Cerebelon (CBN) and leads to the subsequent degradation of the Ikaros (IKZF1) and Aiolos (IKZF3) transcription factors (TF). These TFs play important regulatory roles in lymphocyte development. Despite lenalidomide's importance in MM treatment, several groups have reported that MM patients treated with lenalidomide rarely go on to develop B-cell acute lymphoblastic leukemia (B-ALL). The genetics and clonal relationship between the MM and subsequent B-ALL have not been previously defined. Importantly, it is not clear if the MM and B-ALL arise from the same founding clone that has been under selective pressure during lenalidomide treatment. As deletions in IKZF1 are common in B-ALL, one could hypothesize that lenalidomide's mechanism of action mimics this alteration and contributes to leukemogenesis. We sequenced the tumors from a cohort of seven patients with MM treated with lenalidomide who later developed B-ALL. These data did not show any mutational overlap between the MM and ALL samples-the tumors arose from different founding clones in each case. However, several genes were recurrently mutated in the B-ALL samples across the seven patients. These genes included TP53, ZFP36L2, KIR3DL2, RNASE-L, and TERT. Strikingly, five of the seven patients had a TP53 mutations in the B-ALL sample that was not present in the matched MM sample. The frequency of TP53 mutations in our cohort was much higher than that reported in adult de novo B-ALL patients which can range between 4.1-6.4% (Hernández-Rivas et al. 2017 and Foa et al. 2013). Utilizing CRISPR-Cas9 gene editing, we disrupted the Zfp36l2 or Actb in murine hematopoietic stem cells (HSCs) of mice with or without loss of Trp53. We performed our first transplantation experiment in which the cohorts of mice have loss of Trp53 alone, loss of Zfp36l2 alone, loss of both Trp53 and Zfp36l2, or a control knockout (KO) of Actb. To characterize the disruption of Zfp36l2 alone and in combination with Trp53 we analyzed the hematopoietic stem and progenitor cell compartments in the bone marrow of the above transplanted mice. In mice with a loss of Zfp36l2 there is a decrease in Lin- Sca-1+ c-Kit+ (LSK), short term-HSC (ST-HSC), and multipotent progenitors (MPP). This decrease was not observed in the mice with a loss of both Trp53 and Zfp36l2, where instead we noted an increase in monocyte progenitors (MP), granulocytes-macrophage progenitors (GMP), and common myeloid progenitors (CMP) cells. In this Trp53 Zfp36l2 double loss model we also noted a decrease in B220+ B-cells that was not seen in the Zfp36l2 alone. In this cohort of Trp53 Zfp36l2 loss, we characterized B-cell development through hardy fraction flow cytometry, and identified a decrease in fractions A and B/C (pre-pro and pro-B-cells, respectively) as compared to Zfp36l2 or Actb alone. As lenalidomide does not bind to Cbn in mice, we used the human B-ALL NALM6 cell line to test if treatment with lenalidomide will lead to a selective growth advantage of cells with the same genes knocked out versus wild-type control cells grown in the same culture. We hypothesize that lenalidomide treatment selectively enriched for pre-existing mutated cell clones that evolved into the B-ALL. Preliminary data in NALM6 cells with a loss of TP53 demonstrate a slight increase in cell number at day 7 compared to a RELA control. These experiments will be repeated with concurrent ZFP36L2 and TP53 mutations as well as ZFP36L2 alone. Treatment-related disease is a key consideration when deciding between different treatment options, and this project aims to understand the relationship between MM treatment and B-ALL occurrence. It may be possible to identify MM patients who are at-risk for B-ALL. For example, MM patients who harbor low-level TP53 mutations prior to lenalidomide treatment could be offered alternative treatment options. Disclosures Barnell: Geneoscopy Inc: Current Employment, Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees. Wartman:Novartis: Consultancy; Incyte: Consultancy.

scholarly journals CCND3 is indispensable for the maintenance of B-cell acute lymphoblastic leukemia

Oncogenesis ◽  
2022 ◽  
Vol 11 (1) ◽  
Author(s):  
Franz Ketzer ◽  
Hend Abdelrasoul ◽  
Mona Vogel ◽  
Ralf Marienfeld ◽  
Markus Müschen ◽  
...  
Keyword(s):  
Cell Cycle Progression ◽  
Kinase Activity ◽  
Lymphoblastic Leukemia ◽  
Mrna Level ◽  
Driver Mutations ◽  
Development Of Resistance ◽  
Apoptotic Effect ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Activating Transcription Factor

AbstractThe D-type cyclins (CCND1, CCND2, and CCND3) in association with CDK4/6 are known drivers of cell cycle progression. We reported previously that inactivation of FOXO1 confers growth arrest and apoptosis in B-ALL, partially mediated by subsequent depletion of CCND3. Given that previously the canonical MYC target CCND2 has been considered to play the major role in B-ALL proliferation, further investigation of the role of FOXO1 in CCND3 transcription and the role of CCND3 in B-ALL is warranted. In this study, we demonstrated that CCND3 is essential for the proliferation and survival of B-ALL, independent of the mutational background. Respectively, its expression at mRNA level exceeds that of CCND1 and CCND2. Furthermore, we identified FOXO1 as a CCND3-activating transcription factor in B-ALL. By comparing the effects of CCND3 depletion and CDK4/6 inhibition by palbociclib on B-ALL cells harboring different driver mutations, we found that the anti-apoptotic effect of CCND3 is independent of the kinase activity of the CCND3-CDK4/6 complex. Moreover, we found that CCND3 contributes to CDK8 transcription, which in part might explain the anti-apoptotic effect of CCND3. Finally, we found that increased CCND3 expression is associated with the development of resistance to palbociclib. We conclude that CCND3 plays an essential role in the maintenance of B-ALL, regardless of the underlying driver mutation. Moreover, downregulation of CCND3 expression might be superior to inhibition of CDK4/6 kinase activity in terms of B-ALL treatment.

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