Constitutive activation of the DNA damage response pathway as a novel therapeutic target in diffuse large B-cell lymphoma (original) (raw)
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Dual targeting of the DNA damage response pathway and BCL-2 in diffuse large B-cell lymphoma
2021
Standard chemotherapies for diffuse large B-cell lymphoma (DLBCL), based on the induction of exogenous DNA damage and oxidative stress, are often less effective in the presence of increased MYC and BCL-2 levels, especially in the case of double hit (DH) lymphomas harboring rearrangements of the MYC and BCL-2 oncogenes, which enrich for a patient’s population characterized by refractoriness to anthracycline-based chemotherapy. Here we hypothesized that adaptive mechanisms to MYC-induced replicative and oxidative stress, consisting in DNA damage response (DDR) activation and BCL-2 overexpression, could represent the biologic basis of the poor prognosis and chemoresistance observed in MYC/BCL-2-positive lymphoma. We first integrated targeted gene expression profiling (T-GEP), fluorescence in situ hybridization (FISH) analysis, and characterization of replicative and oxidative stress biomarkers in two independent DLBCL cohorts. The presence of oxidative DNA damage biomarkers identified ...
Molecular biomarkers of DNA damage in diffuse large-cell lymphoma—a review
Journal of Laboratory and Precision Medicine
Diffuse large B-cell lymphoma (DLBCL) is a highly aggressive form of non-Hodgkin's lymphoma with a long-term survival rate of around 60% upon standard treatment with rituximab and chemotherapy. While this marks a great improvement over the pre-rituximab/pre-biologicals era, DLBCLs remain a heterogeneous disease with marked variability in clinical outcome. Efforts have been undertaken to predict its course based on characteristics such as the activated B-cell (ABC) versus germinal centre B-cell (GCB) types, but so far none of these has had much impact on treatment and outcome, and the international prognostic index, based on clinical and basic laboratory features, remains the best risk predictor. This review focuses on 13 biomarkers that have been described in the context of diagnostic tests, clinical studies or basic research related to solid and haematological malignancies in general or DLBCL in particular. These include biomarkers of the DNA repair response such as the phosphorylated histone variant 2AX (γH2AX), p53 binding protein (53BP1), Ataxia telangiectasia mutated protein (ATM), Ataxia telangiectasia and Rad3-related protein (ATR), the DNA-dependent protein kinase (DNA-PK) and Rad51 as well as proto-oncogene products like Myc, B-cell lymphoma 2 (Bcl-2), breast cancer 1 (BRCA1) and signal transducer and activator of transcription 3 (STAT3). We have also included 8-Hydroxy-2'-desoxyguanosine (8-OHdG), a marker for oxidative stress, and discuss a link between two proteins involved in apoptosis, the proteasome activator 28γ (PA28γ) and tumour suppressor p53. Our investigation revealed a connection between almost all biomarkers, which are based on methods such as indirect immunofluorescence, fluorescence in-situ hybridization or immunohistochemistry.
Cancer Immunology, Immunotherapy, 2020
Given the poor prognosis of MYC-overexpressing diffuse large B cell lymphoma (DLBCL) and B cell lymphoma unclassifiable with features intermediate between DLBCL and Burkitt lymphoma/high grade B cell lymphoma (BCLU/HGBL), and preclinical data suggesting that MYC may regulate the antitumor immune response, we sought to characterize expression of immune checkpoint proteins on tumor tissue from patients diagnosed with these lymphomas. Immunohistochemical staining for immune checkpoint protein expression was applied to 56 cases of MYC-overexpressing DLBCL and BCLU/HGBL, 35 of which also harbored MYC rearrangement (MYC-R). Analysis revealed both frequent overexpression of immune checkpoint proteins as well as differences in overexpression patterns based upon MYC-R status, with MYC-R cases more likely to overexpress PD-L1 and PD-1 in the tumor microenvironment (50 vs. 15%, p = 0.02 and 32 vs. 5%, p = 0.02, respectively) but less likely to overexpress CTLA-4 and CD80 on tumor cells (34 vs. 71%, p = 0.01 and 34 vs. 81%, p = 0.001, respectively), as compared to cases without MYC-R. These data may suggest a biologic rationale for investigation of the effect of checkpoint inhibitor therapies in these subgroups of MYC-overexpressing DLBCL and BCLU/HGBL.
Targeting DNA Repair, Cell Cycle, and Tumor Microenvironment in B Cell Lymphoma
Cells, 2020
The DNA double-strand break (DSB) is the most cytotoxic lesion and compromises genome stability. In an attempt to efficiently repair DSBs, cells activate ATM kinase, which orchestrates the DNA damage response (DDR) by activating cell cycle checkpoints and initiating DSB repair pathways. In physiological B cell development, however, programmed DSBs are generated as intermediates for effective immune responses and the maintenance of genomic integrity. Disturbances of these pathways are at the heart of B cell lymphomagenesis. Here, we review the role of DNA repair and cell cycle control on B cell development and lymphomagenesis. In addition, we highlight the intricate relationship between the DDR and the tumor microenvironment (TME). Lastly, we provide a clinical perspective by highlighting treatment possibilities of defective DDR signaling and the TME in mantle cell lymphoma, which serves as a blueprint for B cell lymphomas.
Oncology Research and Treatment, 2016
Pathogenesis of chronic lymphocytic leukemia (CLL) is characterized by specific genetic aberrations and alterations of cellular signaling pathways. In particular, a disturbed DNA damage response (DDR) and an activated B-cell receptor signaling pathway play a major role in promoting CLL cell survival. External stimuli are similarly essential for CLL cell survival and lead to activation of the PI3K/AKT and MAPK pathways. Activation of nuclear factor-kappa B (NFkB) influences the disturbed antiapoptotic balance of CLL cells. Losses or disabling mutations in TP53 and ATM are frequent events in chemotherapy-naïve patients and are further enriched in chemotherapy-resistant patients. As these lesions define key regulatory elements of the DDR pathway, they also determine treatment response to genotoxic therapy. Novel therapeutic strategies therefore try to circumvent defective DDR signaling and to suppress the pro-survival stimuli received from the tumor microenvironment. With increasing knowledge on specific genetic alterations of CLL, we may be able to target CLL cells more efficiently even in the situation of mutated DDR pathways or protection by microenvironmental stimuli.
Leukemia, 2004
CHK1 gene encodes for a serine/threonine kinase involved in the regulation of cell cycle progression and DNA damage checkpoints. To determine the role of CHK1 in the pathogenesis of lymphoid neoplasms and its relationship to other DNA damage response genes, we have analyzed the gene status, protein, and mRNA expression in a series of tumors and nonneoplastic lymphoid tissues. CHK1 protein and mRNA expression levels were very low in both reactive tissues and resting lymphoid cells, whereas tumor samples showed a variable pattern of expression related to their proliferative activity. However, seven aggressive tumors showed a dissociate pattern of extremely low or negative protein expression in spite of a high proliferative activity. Four of these tumors were diffuse large B-cell lymphomas (DLCLs) with concordant reduced levels of mRNA, whereas one blastoid mantle cell lymphoma (B-MCL) and two DLCLs had relatively normal levels of mRNA. No gene mutations, deletions, or hypermethylation of the promoter region were detected in any of these cases. In all these tumors ATM, CHK2, and p53 genes were wild type. These findings suggest that CHK1 inactivation in NHLs occurs by loss of protein expression in a subset of aggressive variants alternatively to ATM, CHK2, and p53 alterations.
DNA repair genes are selectively mutated in diffuse large B cell lymphomas
Journal of Experimental Medicine, 2013
DNA repair mechanisms are fundamental for B cell development, which relies on the somatic diversification of the immunoglobulin genes by V(D)J recombination, somatic hypermutation, and class switch recombination. Their failure is postulated to promote genomic instability and malignant transformation in B cells. By performing targeted sequencing of 73 key DNA repair genes in 29 B cell lymphoma samples, somatic and germline mutations were identified in various DNA repair pathways, mainly in diffuse large B cell lymphomas (DLBCLs). Mutations in mismatch repair genes (EXO1, MSH2, and MSH6) were associated with microsatellite instability, increased number of somatic insertions/deletions, and altered mutation signatures in tumors. Somatic mutations in nonhomologous end-joining (NHEJ) genes (DCLRE1C/ARTEMIS, PRKDC/DNA-PKcs, XRCC5/KU80, and XRCC6/KU70) were identified in four DLBCL tumors and cytogenetic analyses revealed that translocations involving the immunoglobulin-heavy chain locus occurred exclusively in NHEJ-mutated samples. The novel mutation targets, CHEK2 and PARP1, were further screened in expanded DLBCL cohorts, and somatic as well as novel and rare germline mutations were identified in 8 and 5% of analyzed tumors, respectively. By correlating defects in a subset of DNA damage response and repair genes with genomic instability events in tumors, we propose that these genes play a role in DLBCL lymphomagenesis.
Blood, 2010
Several drugs used for diffuse large B-cell lymphoma (DLBCL) treatment rely on DNA damage for tumor cell killing. We verified the prognostic impact of the host DNA repair genotype in 2 independent cohorts of DLBCL treated with R-CHOP21 (training cohort, 163 cases; validation cohort, 145 cases). Among 35 single nucleotide polymorphisms analyzed in the training series, MLH1 rs1799977 was the sole predicting overall survival. DLBCL carrying the MLH1 AG/GG genotype displayed an increased death risk (hazard ratio [HR] = 3.23; P < .001; q =0 .009) compared with patients carrying the AA genotype. Multivariate analysis adjusted for International Prognostic Index identified MLH1 AG/GG as an independent OS predictor (P < .001). The poor prognosis of MLH1 AG/GG was the result of an increased risk of failing both R-CHOP21 (HR = 2.02; P = .007) and platinum-based second-line (HR = 2.26; P = .044) treatment. Survival analysis in the validation series confirmed all outcomes predicted by MLH1...