Internal Medicine I
Contributions
Type: Oral Presentation
Presentation during EHA20: From 13.06.2015 12:30 to 13.06.2015 12:45
Location: Room Lehar 3 + 4
Background
Chronic antigenic stimulation may has been hypothesized to play an important role in the pathogenesis of malignant lymphomas. We have previously shown that a hyperglycosylated version of neurabin/SAMD14, a protein strongly expressed in the CNS, is the antigenic target of the B-cell receptor (BCR) of 2/3 of all primary CNS lymphomas, but antigenic targets of peripheral DLBCL-BCRs have not been defined to date.
Aims
To identify the antigenic targets / stimuli of BCR derived from peripheral DLBCL.
Methods
BCRs were expressed as recombinant Fabs based on corresponding pairs of functional variable region heavy and light chain genes, which had been amplified from isolated genomic DNA of snap-frozen lymphoma specimens and DLBCL-derived cell lines. The purified BCR-Fabs were checked for binding to proteins expressed on macroarrays of human cDNA expression libraries.
Results
The BCR from 10 DLBCL cell lines (5 of the germinal center type and 5 of the activated B-cell type) were tested on the protein macroarray. None of the GC-type BCR reacted with any of the proteins expressed on the protein macroarrays, but the BCR from 3/5 (60%) of the ABC-derived cell lines reacted with ARS2 (arsenite resistance protein 2), a conserved mammalian protein which is important for microRNA biogenesis. Isoelectric focusing and phosphatase treatment of ARS2 derived from ABC cell lines with a BCR specific for ARS2 revealed that ARS2 was hypophosphorylated (hypo-ARS2) in the respective cell lines. Analysis of peripheral blood lymphocytes from patients with DLBCL of unknown cell of origin and healthy controls revealed that 5/100 patients (5%), but only 1/200 controls (0.5%) were carriers of hypo-ARS2, resulting in a 10x increased risk for healthy carriers of hypo-ARS2 to develop DLBCL. All patients with BCRs targeting ARS2 had polyclonal antibodies against ARS2 in their serum.
Summary
Hypo-ARS2 is the first molecular defined risk factor for DLBCL identified to date. The increased risk for healthy carriers of this posttranslational modification to develop DLBCL supports the hypothesis of chronic antigenic stimulation as an important factor in the pathogenesis of DLBCL of the ABC subtype and indicates that posttranslationally modified autoantigens are a frequent target and stimulus for ABC-DLBCL-BCR. That antibodies against ARS2 are found in the respective patients suggests that the hypo-ASR reactive DLBCL evolves from a polyclonal B-cell response against this autoantigen. Investigations into the mechanism underlying the hypophosphorylation of ARS2 are underway and therapeutic options will be discussed. Supported by Wilhelm-Sander-Stiftung.
Keyword(s): Autoimmunity, DLBCL, VH gene
Session topic: Oncogenic mechanisms and novel targets in non-Hodgkin's lymphoma
Type: Oral Presentation
Presentation during EHA20: From 13.06.2015 12:30 to 13.06.2015 12:45
Location: Room Lehar 3 + 4
Background
Chronic antigenic stimulation may has been hypothesized to play an important role in the pathogenesis of malignant lymphomas. We have previously shown that a hyperglycosylated version of neurabin/SAMD14, a protein strongly expressed in the CNS, is the antigenic target of the B-cell receptor (BCR) of 2/3 of all primary CNS lymphomas, but antigenic targets of peripheral DLBCL-BCRs have not been defined to date.
Aims
To identify the antigenic targets / stimuli of BCR derived from peripheral DLBCL.
Methods
BCRs were expressed as recombinant Fabs based on corresponding pairs of functional variable region heavy and light chain genes, which had been amplified from isolated genomic DNA of snap-frozen lymphoma specimens and DLBCL-derived cell lines. The purified BCR-Fabs were checked for binding to proteins expressed on macroarrays of human cDNA expression libraries.
Results
The BCR from 10 DLBCL cell lines (5 of the germinal center type and 5 of the activated B-cell type) were tested on the protein macroarray. None of the GC-type BCR reacted with any of the proteins expressed on the protein macroarrays, but the BCR from 3/5 (60%) of the ABC-derived cell lines reacted with ARS2 (arsenite resistance protein 2), a conserved mammalian protein which is important for microRNA biogenesis. Isoelectric focusing and phosphatase treatment of ARS2 derived from ABC cell lines with a BCR specific for ARS2 revealed that ARS2 was hypophosphorylated (hypo-ARS2) in the respective cell lines. Analysis of peripheral blood lymphocytes from patients with DLBCL of unknown cell of origin and healthy controls revealed that 5/100 patients (5%), but only 1/200 controls (0.5%) were carriers of hypo-ARS2, resulting in a 10x increased risk for healthy carriers of hypo-ARS2 to develop DLBCL. All patients with BCRs targeting ARS2 had polyclonal antibodies against ARS2 in their serum.
Summary
Hypo-ARS2 is the first molecular defined risk factor for DLBCL identified to date. The increased risk for healthy carriers of this posttranslational modification to develop DLBCL supports the hypothesis of chronic antigenic stimulation as an important factor in the pathogenesis of DLBCL of the ABC subtype and indicates that posttranslationally modified autoantigens are a frequent target and stimulus for ABC-DLBCL-BCR. That antibodies against ARS2 are found in the respective patients suggests that the hypo-ASR reactive DLBCL evolves from a polyclonal B-cell response against this autoantigen. Investigations into the mechanism underlying the hypophosphorylation of ARS2 are underway and therapeutic options will be discussed. Supported by Wilhelm-Sander-Stiftung.
Keyword(s): Autoimmunity, DLBCL, VH gene
Session topic: Oncogenic mechanisms and novel targets in non-Hodgkin's lymphoma