Contributions
Abstract: EP851
Type: E-Poster Presentation
Session title: Lymphoma Biology & Translational Research
Background
Mantle cell lymphoma (MCL) is an often rapidly progressing accumulation of lymphocytes with generalized lymphadenopathy, and common involvement of peripheral blood and bone marrow (BM). Translocation t(11;14), leading to overexpression of cyclin D1 (CCND1), is one of the primary events in MCL development.
Aims
Here, we investigate the transcriptome of MCL cells from eight BM samples to provide insight into the complex and diverse molecular architecture of MCL at the single-cell expression level.
Methods
Transcriptome analysis was performed on viable CD19+ cells sorted from diagnostic cryopreserved BM cells of eight MCL patients. All patients had nodal and BM involvement, were positive for CCND1 and SOX11 and displayed an otherwise heterogeneous clinical presentation. A concentration of 1400 cells/µl were used for single-cell mRNA sequencing (ScRNA-seq) using the 10x Chromium System and Illumina NovaSeq 6000. Data analysis was performed with Cell Ranger (10x Genomics) and R (Seurat 3.2).
Results
ScRNA-seq revealed transcriptional inter-tumor heterogeneity across the MCL patients. Expression analysis identified distinct subsets of non-malignant pre-pro B/pro-B cells with similar expression profiles across patients. MCL cells showed enrichment of genes involved in key pathways associated with B cell malignancies, such as PI3K/AKT/mTOR and NFκB.
Generally, the cell populations were transcriptionally defined as CD20+CD45+CD5low/-CD19 low/-CD23 low/-CD27 low/-. While the light chain restriction was in overall concordant with the clinical laboratory analyses, we found a median of 9.5% (0.1–24.4%) of the light chain expressing cells that were both κ and λ positive. Also, on the single-cell transcription level, we demonstrated that CD23 was present in a subset of the SOX11+ MCL cells (1.45–9.29%), supporting previous findings that some MCLs are CD23+, although this marker is frequently used to differentiate chronic lymphocytic leukemia from MCL. While 85% of all SOX11+ cells were positive for IgM (35–98%) and 17% for IgD (1–43%), all patients had SOX11+ cells expressing IgA (2–47%) and IgG (1–15%), and patient 1–6 had a small CD27+SOX11+ fraction, suggesting that some of the MCL cells may be antigen-experienced although expected to originate from naïve B cells. While all patients displayed SOX11 and CCND1 expression in concordance to the clinical laboratory results, only 35% of the total single-cell cohort were marked SOX11+, and of the SOX11 positive cells 70.6% (44.59–81.47%) co-expressed CCND1 at a detectable level. Additionally, 4.49% of all cells expressed SOX4, a marker of more immature B cells, and 3.07% of these cells were SOX11+. Not surprisingly, the expression levels of the classical MCL markers such as e.g. SOX11, CCND1, CD5, CD19 and CD20 were highly correlated (p=0.02, ρ=0.99), even though CD19 and to a larger degree CD5 were only detectable in a subset of cells.
We found that a blastoid MCL case (patient 1) was marked by a subset of cells expressing both SOX11 and SOX4 together with a presentation of protocadherin FAT1, which was exclusively expressed in this patient (20% of SOX11+ cells). FAT1 is a specific marker in acute lymphoblastic leukemia, and SOX4 plays a central role in survival of malignant lymphoblasts, thus these markers, posed for further investigation, may help establish differentiation state and possibly prognosis.
Conclusion
Our study demonstrates inter-tumor heterogeneity of MCL, characterizes MCL-specific expression profiles and provides insight into clinical markers at the single-cell transcription level.
Keyword(s): Mantle cell lymphoma
Abstract: EP851
Type: E-Poster Presentation
Session title: Lymphoma Biology & Translational Research
Background
Mantle cell lymphoma (MCL) is an often rapidly progressing accumulation of lymphocytes with generalized lymphadenopathy, and common involvement of peripheral blood and bone marrow (BM). Translocation t(11;14), leading to overexpression of cyclin D1 (CCND1), is one of the primary events in MCL development.
Aims
Here, we investigate the transcriptome of MCL cells from eight BM samples to provide insight into the complex and diverse molecular architecture of MCL at the single-cell expression level.
Methods
Transcriptome analysis was performed on viable CD19+ cells sorted from diagnostic cryopreserved BM cells of eight MCL patients. All patients had nodal and BM involvement, were positive for CCND1 and SOX11 and displayed an otherwise heterogeneous clinical presentation. A concentration of 1400 cells/µl were used for single-cell mRNA sequencing (ScRNA-seq) using the 10x Chromium System and Illumina NovaSeq 6000. Data analysis was performed with Cell Ranger (10x Genomics) and R (Seurat 3.2).
Results
ScRNA-seq revealed transcriptional inter-tumor heterogeneity across the MCL patients. Expression analysis identified distinct subsets of non-malignant pre-pro B/pro-B cells with similar expression profiles across patients. MCL cells showed enrichment of genes involved in key pathways associated with B cell malignancies, such as PI3K/AKT/mTOR and NFκB.
Generally, the cell populations were transcriptionally defined as CD20+CD45+CD5low/-CD19 low/-CD23 low/-CD27 low/-. While the light chain restriction was in overall concordant with the clinical laboratory analyses, we found a median of 9.5% (0.1–24.4%) of the light chain expressing cells that were both κ and λ positive. Also, on the single-cell transcription level, we demonstrated that CD23 was present in a subset of the SOX11+ MCL cells (1.45–9.29%), supporting previous findings that some MCLs are CD23+, although this marker is frequently used to differentiate chronic lymphocytic leukemia from MCL. While 85% of all SOX11+ cells were positive for IgM (35–98%) and 17% for IgD (1–43%), all patients had SOX11+ cells expressing IgA (2–47%) and IgG (1–15%), and patient 1–6 had a small CD27+SOX11+ fraction, suggesting that some of the MCL cells may be antigen-experienced although expected to originate from naïve B cells. While all patients displayed SOX11 and CCND1 expression in concordance to the clinical laboratory results, only 35% of the total single-cell cohort were marked SOX11+, and of the SOX11 positive cells 70.6% (44.59–81.47%) co-expressed CCND1 at a detectable level. Additionally, 4.49% of all cells expressed SOX4, a marker of more immature B cells, and 3.07% of these cells were SOX11+. Not surprisingly, the expression levels of the classical MCL markers such as e.g. SOX11, CCND1, CD5, CD19 and CD20 were highly correlated (p=0.02, ρ=0.99), even though CD19 and to a larger degree CD5 were only detectable in a subset of cells.
We found that a blastoid MCL case (patient 1) was marked by a subset of cells expressing both SOX11 and SOX4 together with a presentation of protocadherin FAT1, which was exclusively expressed in this patient (20% of SOX11+ cells). FAT1 is a specific marker in acute lymphoblastic leukemia, and SOX4 plays a central role in survival of malignant lymphoblasts, thus these markers, posed for further investigation, may help establish differentiation state and possibly prognosis.
Conclusion
Our study demonstrates inter-tumor heterogeneity of MCL, characterizes MCL-specific expression profiles and provides insight into clinical markers at the single-cell transcription level.
Keyword(s): Mantle cell lymphoma