Dataset Information

Apoptotic Blocks in Primary Non-Hodgkin B Cell Lymphomas Identified by BH3 Profiling.

ABSTRACT: To determine causes of apoptotic resistance, we analyzed 124 primary B cell NHL samples using BH3 profiling, a technique that measures the mitochondrial permeabilization upon exposure to synthetic BH3 peptides. Our cohort included samples from chronic lymphocytic leukemia (CLL), follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL), high-grade B cell lymphoma with translocations in MYC and BCL2 (HGBL-DH), mantle cell lymphoma (MCL) and marginal zone lymphoma (MZL). While a large number of our samples displayed appropriate responses to apoptosis-inducing peptides, pro-apoptotic functional defects, implicating BAX, BAK, BIM or BID, were seen in 32.4% of high-grade NHLs (12/37) and in 3.4% of low-grade NHLs (3/87, p < 0.0001). The inhibition of single anti-apoptotic proteins induced apoptosis in only a few samples, however, the dual inhibition of BCL2 and MCL1 was effective in 83% of samples, indicating MCL1 was the most common cause of lack of response to the BCL2 inhibitor, venetoclax. We then profiled Toledo and OCI-Ly8 high-grade lymphoma cell lines to determine which drugs could reduce MCL1 expression and potentiate venetoclax responses. Doxorubicin and vincristine decreased levels of MCL1 and increased venetoclax-induced apoptosis (all p < 0.05). Overall, in primary NHLs expressing BCL2 that have no defects in pro-apoptotic signaling, a poor response to venetoclax is primarily due to the presence of MCL1, which may be overcome by combining venetoclax with doxorubicin and vincristine-based chemotherapy or with other anti-microtubule inhibitors.

SUBMITTER: Rys RN

PROVIDER: S-EPMC7957722 | biostudies-literature | 2021 Feb

REPOSITORIES: biostudies-literature

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Apoptotic Blocks in Primary Non-Hodgkin B Cell Lymphomas Identified by BH3 Profiling.

Rys Ryan N RN Wever Claudia M CM Geoffrion Dominique D Goncalves Christophe C Ghassemian Artin A Brailovski Eugene E Ryan Jeremy J Stoica Liliana L Hébert Josée J Petrogiannis-Haliotis Tina T Dmitrienko Svetlana S Frenkiel Saul S Staiger Annette A Ott German G Steidl Christian C Scott David W DW Sesques Pierre P Del Rincon Sonia S Mann Koren K KK Letai Anthony A Johnson Nathalie A NA

Cancers 20210228 5

To determine causes of apoptotic resistance, we analyzed 124 primary B cell NHL samples using BH3 profiling, a technique that measures the mitochondrial permeabilization upon exposure to synthetic BH3 peptides. Our cohort included samples from chronic lymphocytic leukemia (CLL), follicular lymphoma (FL), diffuse large B-cell lymphoma (DLBCL), high-grade B cell lymphoma with translocations in <i>MYC</i> and <i>BCL2</i> (HGBL-DH), mantle cell lymphoma (MCL) and marginal zone lymphoma (MZL). While ...[more]

PMID: 33670870

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Project description:We have previously reported a novel constitutively overexpressed 21 kDa protein in Hodgkin Lymphoma (HL) and aggressive Non-Hodgkin Lymphomas (NHL). The objective of the current study was to 1) identify this protein using two independent methods, 2) study the expression of the protein and its encoding mRNA in reactive lymph nodes, normal lymphocytes and CD34+ bone marrow precursor cells, 3) analyse patterns of expression of the protein in tissue microarrays assembled from a large number of diagnostic clinical biopsies from patients with HL, and 4) determine the copy number variation and mutation status of the encoding gene in HL cell lines.Peptide sequencing by LC-MS/MS and protein identification by protein array screening identified a single protein, CYB5B. No mutations were detected in the CYB5B gene in HL cell lines. Quantitative PCR showed CYB5B gene expression was increased in HL and NHL cell lines. Array CGH using a submegabase resolution tiling array revealed gains in the CYB5B locus in HL cell lines KMH2 and L428. Membrane expression was seen in Reed-Sternberg cells in clinical biopsies from patients with HL but not in reactive lymph nodes. Bone marrow CD34+ precursor cells were CYB5B negative on the cell surface. RT-PCR assays of RNA extracted from T and B cell enriched fractions obtained from normal peripheral blood mononuclear cells, reactive lymph nodes, tonsils and normal bone marrow samples showed no evidence of increased mRNA levels of CYB5B in comparison to housekeeping gene GAPDH.The 21 kDa protein overexpressed in HL and aggressive NHL is identical to CYB5B. CYB5B gene expression is increased in a subset of HL and NHL cell lines tested. This is associated with CYB5B gene amplification in HL cell lines KMH2 and L428. CYB5B may be a potential target for antibody-based therapy of HL and aggressive NHL as although cytoplasmic expression is present in reactive lymphocytes, it is not expressed on the cell surface of non-neoplastic lymphocytes or bone marrow precursor cells.

Project description:Ammonium hydroxide and pyrrolidine eluents were dried (SpeedVac) and reconstituted in 25 ul sample loading buffer (0.1% TFA/2% acetonitrile). Eluent from phosphotyrosine immunoprecipitation was dried and reconstituted in 35 ul of the loading buffer. An LTQ Orbitrap XL (ThermoFisher) in-line with a Paradigm MS2 HPLC (Michrom bioresources) was employed for acquiring high-resolution MS and MS/MS data. Ten microliters of the phospho-enriched peptides were loaded onto a sample trap (Captrap, Bruker-Michrom) in-line with a nano-capillary column (Picofrit, 75 um i.d.x 15 um tip, New Objective) packed in-house with 10 cm of MAGIC AQ C18 reverse phase material (Michrom Bioresource). Two different gradient programs, one each for MOAC and phosphotyrosine immunoprecipitation samples, were used for peptide elution. For MOAC samples, a gradient of 5-40% buffer B (95% acetonitrile/1% acetic acid) in 135 min and 5 min wash with 100% buffer B followed by 30 min of re-equilibration with buffer A (2% acetonitrile/1% acetic acid) was used. For phosphotyrosine immunoprecipitation samples, which were a much less complex mixture of peptides, 5-40% gradient with buffer B was achieved in 75 min followed by 5 min wash with buffer B and 30 min re-equilibration. Flow rate was ~0.3 ul/min. Peptides were directly introduced into the mass spectrometer using a nano-spray source. Orbitrap was set to collect 1 MS scan between 400-2000 m/z (resolution of 30,000 @ 400 m/z) in orbitrap followed by data dependent CID spectra on top 9 ions in LTQ (normalized collision energy ~35%). Dynamic exclusion was set to 2 MS/MS acquisitions followed by exclusion of the same precursor ion for 2 min. Maximum ion injection times were set to 300 ms for MS and 100 ms for MS/MS. Automatic Gain Control (AGC) was set to 1xe6 for MS and 5000 for MS/MS. Charge state screening was enabled to discard +1 and unassigned charge states. Technical duplicate data for each of the MOAC elutions (ammonium hydroxide and pyrrolidine) and triplicate data for the phosphotyrosine immunoprecipitation samples were acquired. RAW files were converted to mzXML using msconvert and searched against the Swissprot Human protein database (2013-Jan release) appended with common proteomics contaminants and reverse sequences as decoys. Searches were performed with X!Tandem (version 2010.10.01.1) using the k-score plugin. For all searches the following search parameters were used: Parent monoisotopic mass error of 50 ppm; fragment ion error of 0.8 Daltons; allowing for up to 2 missed tryptic cleavages. Variable modifications were oxidation of Methionine (+15.9949@M), carbamidomethylation of Cysteine (+57.0214@C), and phosphorylation of Serine, Threonine, and Tyrosine (+79.9663@[STY]). The search results were then post-processed using PeptideProphet and ProteinProphet.

Dataset Information

Apoptotic Blocks in Primary Non-Hodgkin B Cell Lymphomas Identified by BH3 Profiling.

Publications

Apoptotic Blocks in Primary Non-Hodgkin B Cell Lymphomas Identified by BH3 Profiling.

Similar Datasets

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