Project description:MYC-translocated T-lineage acute lymphoblastic leukemia (T-ALL) is a rare subgroup of T-ALL associated with CDKN2A/B deletions, PTEN inactivation, and absence of NOTCH1 or FBXW7 mutations. This subtype of T-ALL has been associated with induction failure and aggressive disease. Identification of drug targets and mechanistic insights for this disease are still limited. Here, we established a human NOTCH1-independent MYC-translocated T-ALL cell line that maintains the genetic and phenotypic characteristics of the parental leukemic clone at diagnosis. The University of Padua T-cell acute lymphoblastic leukemia 13 (UP-ALL13) cell line has all the main features of the above described MYC-translocated T-ALL. Interestingly, UP-ALL13 was found to harbor a heterozygous R882H DNMT3A mutation typically found in myeloid leukemia. Chromatin immunoprecipitation coupled with high-throughput sequencing for histone H3 lysine 27 (H3K27) acetylation revealed numerous putative super-enhancers near key transcription factors, including MYC, MYB, and LEF1. Marked cytotoxicity was found following bromodomain-containing protein 4 (BRD4) inhibition with AZD5153, suggesting a strict dependency of this particular subtype of T-ALL on the activity of super-enhancers. Altogether, this cell line may be a useful model system for dissecting the signaling pathways implicated in NOTCH1-independent T-ALL and for the screening of targeted anti-leukemia agents specific for this T-ALL subgroup.
Project description:The chromosomal translocation t(8;14)(q24;q32) with juxtaposition of MYC to enhancer elements in the immunoglobulin heavy chain (IGH) gene locus is the genetic hallmark of the majority of Burkitt lymphoma and a subset of Diffuse large B-cell lymphoma patients. Around 3% of adult B-lineage acute lymphoblastic leukemia (ALL) patients show this aberration. Flow cytometry mostly reveals a "mature B-ALL" or "Burkitt-type" ALL immunophenotype. Using long-distance PCR for t(8;14)/MYC-IGH fusion, we investigated bone marrow, peripheral blood and a few other samples with suspected Burkitt-ALL or mature B-ALL and identified 133 MYC-IGH-positive cases. The location of the chromosomal breaks in the IGH joining and the 8 different switch regions was determined using a set of long-distance PCRs. The chromosomal breakpoints with the adjacent MYC regions on 8q24 were characterized by direct sequencing in 49 cases. The distribution of chromosomal breaks among the IGH joining and switch regions was the following: JH 23.3%, M 21.8%, G1 15.0%, G2 7.5%, G3 3.8%, G4 4.5%, A1 12.8%, A2 3.8%, E 7.5%. Two breakpoint clusters near MYC were delineated. There was no clear correlation between the degree of somatic hypermutation and the chromosomal break locations. Epstein Barr virus was detected in 5 cases (4%). This detailed and extensive molecular analysis illustrates the molecular complexity of the MYC-IGH translocations and the detected distribution of breakpoints provides additional evidence that this translocation results from failed switch and VDJ recombinations. This study may serve as a model for the analysis of other IGH translocations in B-cell lymphoma.
Project description:We cloned the t(10;14) recurrent translocation from CD3-negative T-cell acute lymphoblastic leukemia cells. The breakpoint at 14q11 involved an intermediate rearrangement of the delta T-cell receptor locus, suggesting that the translocation arose at the time of antigen receptor assemblage. Translocation introduced chromosome segment 10q24 as proven by hybridization of a breakpoint-derived probe to flow-sorted chromosomes and metaphase chromosomes. Two t(10;14) breakpoints were clustered within a 600-base-pair region of 10q24 but no heptamer-spacer-nonamer motifs resembling T-cell receptor/immunoglobulin rearrangement signals were noted at the breakpoint. A locus distinct from terminal deoxynucleotidyltransferase was found at 10q24. Evolutionarily conserved regions surrounding the 10q24 breakpoint were examined for transcriptional activity. A region telomeric to the 10q24 breakpoint, expected to translocate to the der(14) chromosome, recognized an abundant 2.9-kilobase RNA in a t(10;14) T-cell leukemia. This locus was not active in a variety of other normal and neoplastic T cells, arguing that it was deregulated by the introduction of the T-cell receptor. This locus is a candidate for a putative protooncogene, TCL3, involved in T-cell neoplasia.
Project description:BackgroundLymphoblastic lymphoma (LBL) and acute lymphoblastic leukemia (ALL) are categorized as the same entity under precursor lymphoid neoplasms in the World Health Organization classification. However, compared to B-cell ALL, the molecular genetic makeup of B-cell LBL remains to be understood, mainly due to its rarity. We performed whole exome sequencing (WES) on seven patients with TCF3-PBX1-positive B-cell LBL.MethodsWES was performed using DNA extracted from tumor specimens and paired blood samples at remission for six patients, and tumor-only analysis was performed for one patient whose remission sample was not available. For one patient, a relapsed sample was also analyzed.ResultsKMT2D variants and 6q LOH were found as recurrent alterations. Somatic variants of KMT2D were identified in three of the seven patients. Of note, the two patients with heterozygous nonsense variant of KMT2D were at stage III, without bone marrow infiltration. 6q LOH was also identified in two others, out of the seven patients. The common 6q deleted region of the two patients ranged from 6q12 to 6q16.3. Both patients had bone marrow infiltration. Analysis of recurrent case also revealed that the relapsed clone might be derived from a minor clone of the bone marrow at diagnosis.ConclusionIn this study, through WES for seven patients with TCF3-PBX1-positive B-LBL, we identified KMT2D mutations and 6q LOH as recurrent alterations. In order to elucidate the relationship between these recurrent alterations and disease specificity or outcomes, further studies comparing with TCF3-PBX1-positive B-ALL are required.
Project description:Lymphoma DNA of five patients was analyzed using Affymetrix Genome-Wide Human SNP Array 6.0 according to the manufacturer’s instructions.
Project description:We describe two follicular lymphoma (FL) patients with MYC/BCL2 double- and MYC/BCL2/BCL6 triple-hit translocations. The first patient (case 1) was a man in his 30s who presented with stage IV disease with leukemic manifestation. The second patient (case 2) was a man in his 60s who presented with relapsed FL, but his disease was in a limited stage. Histopathology of the lymph node biopsies revealed grade 3A FL in both cases. MYC positivity and the Ki-67-labeling index were 60-70 and 20% in case 1 and 30 and 50% in case 2, respectively. G-banding revealed t(8;14;18)(q24;q32;q21) in both cases and fluorescence in situ hybridization using MYC, IGH, and BCL2 break-apart probes confirmed t(8;14;18)(+5'BCL2,-3'MYC;+3'MYC,-5'IGH;+5'IGH,-5'BCL2). In case 2, additional materials of der(8)t(8;14;18) were duplicated and translocated to chromosome Y, and t(3;16)(q27;p13)/BCL6::CIITA was identified. We obtained BCL2-major breakpoint region::IGHJ5::IGHG1 and MYC exon 2::IGHA2 fusion sequences by long-distance polymerase chain reaction in case 1, and proposed that t(8;14;18) was generated by two-step translocations and that BCL2::IGH and MYC::IGH involved the same IGH allele. Both patients responded to the standard chemotherapy for FL. We suggest that the presence of t(8;14;18) in FL does not immediately indicate high-grade transformation and aggressive clinical behavior requiring intensive chemotherapy.
Project description:We describe two patients with primary diffuse large B-cell lymphoma of the central nervous system (PCNS-DLBCL). The first patient (case 1) was a woman in her late 70s who presented with a tumor in the left frontal lobe, whereas the second patient (case 2) was a man in his early 70s who presented with a left frontal lobe tumor associated with intratumoral hemorrhage. The histopathology of the tumor specimen disclosed the proliferation of large cells with centroblastic (case 1) or immunoblastic/plasmablastic (case 2) cytomorphology and an accumulation of the tumor cells within the perivascular space. The cells in both cases were positive for CD20, CD79a, BCL6, IRF4/MUM1, MYC, and BCL2 and negative for CD5 and CD10. G-banding revealed t(8;14)(q24;q32) in case 1, and the tetraploid-range karyotype including two or three copies of der(3)t(3;14)(q27;q32) and der(14)t(3;14)(q27;q32) in case 2. Fluorescence in situ hybridization applied to metaphase spreads confirmed colocalization of MYC and IGH (case 1) and BCL6 and IGH (case 2) hybridization signals on the relevant derivative chromosomes. Case 1 carried the MYD88L265P mutation. This case report provides clear evidence for the occurrence of t(8;14)(q24;q32) and t(3;14)(q27;q32) in PCNS-DLBCL using metaphase-based cytogenetic analysis.
Project description:Human acute T-cell lymphoblastic leukemias and lymphomas (T-ALL) are commonly associated with gain-of-function mutations in Notch1 that contribute to T-ALL induction and maintenance. Starting from an expression-profiling screen, we identified c-myc as a direct target of Notch1 in Notch-dependent T-ALL cell lines, in which Notch accounts for the majority of c-myc expression. In functional assays, inhibitors of c-myc interfere with the progrowth effects of activated Notch1, and enforced expression of c-myc rescues multiple Notch1-dependent T-ALL cell lines from Notch withdrawal. The existence of a Notch1-c-myc signaling axis was bolstered further by experiments using c-myc-dependent murine T-ALL cells, which are rescued from withdrawal of c-myc by retroviral transduction of activated Notch1. This Notch1-mediated rescue is associated with the up-regulation of endogenous murine c-myc and its downstream transcriptional targets, and the acquisition of sensitivity to Notch pathway inhibitors. Additionally, we show that primary murine thymocytes at the DN3 stage of development depend on ligand-induced Notch signaling to maintain c-myc expression. Together, these data implicate c-myc as a developmentally regulated direct downstream target of Notch1 that contributes to the growth of T-ALL cells.
Project description:We investigated whether the outcome prediction of patients with aggressive B-cell lymphoma can be improved by combining clinical, molecular genotype, and radiomics features. MYC, BCL2, and BCL6 rearrangements were assessed using fluorescence in situ hybridization. Seventeen radiomics features were extracted from the baseline positron emission tomography-computed tomography of 323 patients, which included maximum standardized uptake value (SUVmax), SUVpeak, SUVmean, metabolic tumor volume (MTV), total lesion glycolysis, and 12 dissemination features pertaining to distance, differences in uptake and volume between lesions, respectively. Logistic regression with backward feature selection was used to predict progression after 2 years. The predictive value of (1) International Prognostic Index (IPI); (2) IPI plus MYC; (3) IPI, MYC, and MTV; (4) radiomics; and (5) MYC plus radiomics models were tested using the cross-validated area under the curve (CV-AUC) and positive predictive values (PPVs). IPI yielded a CV-AUC of 0.65 ± 0.07 with a PPV of 29.6%. The IPI plus MYC model yielded a CV-AUC of 0.68 ± 0.08. IPI, MYC, and MTV yielded a CV-AUC of 0.74 ± 0.08. The highest model performance of the radiomics model was observed for MTV combined with the maximum distance between the largest lesion and another lesion, the maximum difference in SUVpeak between 2 lesions, and the sum of distances between all lesions, yielding an improved CV-AUC of 0.77 ± 0.07. The same radiomics features were retained when adding MYC (CV-AUC, 0.77 ± 0.07). PPV was highest for the MYC plus radiomics model (50.0%) and increased by 20% compared with the IPI (29.6%). Adding radiomics features improved model performance and PPV and can, therefore, aid in identifying poor prognosis patients.
Project description:RNA sequencing analysis revealed a different expression profile between two different T-ALL subgroups, namely MYC-TCRAD translocated T-ALL vs TAL1-LMO2 T-ALL.