Contributions
Abstract: EP334
Type: E-Poster Presentation
Session title: Acute lymphoblastic leukemia - Biology & Translational Research
Background
B-cell acute lymphoblastic leukemia (B-ALL) is an aggressive type of acute leukemia. Despite the high complete remission (CR) rate following first-line therapy, treatment refractoriness and frequent recurrence are remained to be solved. Immunotherapy and targeted therapy have been confirmed as the effective approach for refractory and relapse (r/r) B-ALL. Although immunotherapy has achieved higher complete remission rate, remission stage can be destroyed by genomic heterogeneity and instability. Mechanistically, the occurrence of r/r B-ALL not only relied on intrinsic properties of malignant leukemic cells, but also on extrinsic protective environment provided by the tumor microenvironment (TME), especially bone marrow (BM) TME.
Aims
To clarify the transcriptome patterns in BM cells of B-ALL, single cell RNA sequencing (scRNA-seq) data was performed to be analyzed.
Methods
ScRNA-seq data of BM cells from 3 B-ALL patients were obtained from the Gene Expression Omnibus (GEO, GSE130116). Raw data was firstly processed by Seurat package. After quality control and data normalization, variable genes were extracted for dimensionality reduction. Principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE) were then executed to cluster cells, following with cell types’ classification. To determine the features of cell subgroups, B cell and dendritic cell (DC) were isolated respectively and followed with gene expression analysis. Finally, pseudo-time analysis functioned by Monocle package was performed to display cell development trajectory and gene expression features over time.
Results
Based on cell clustering, 9 cell types were profiled in B-ALL BM, including naïve and memory CD4+ T cell, CD14+ monocyte, B cell, CD8+ T cell, FCGRA3+monocyte, nature killer (NK) cell, DC, and platelet (Fig.1A). Top 10 marker genes in each cell cluster were exhibited in heat map, demonstrating an effective cell classification (Fig.1B). Differential gene analysis further revealed that PD-L1 (CD274) was hardly expressed on BM cells while TMEM173 (STING), NFKB1 (NF-κB) were widespread, especially on immune cells (Fig.2A). In particular, elevation of STING and NF-κB indicated that BM cells were sensitive to the type I innate immune response rather than PD-1 mediated response (Fig.2B).
Previous studies had revealed that immune cells activation and tumor cell pyroptosis could be induced by STING. To analyze the features of STING and its downstream molecules in B-ALL BM cells, DCs and B cells were isolated from total cells respectively. DCs were separated into 3 subtypes, including monocyte derived DC, CD1C-CD14-DC and myeloid conventional DC (Fig.3A). Gene expression analysis confirmed that the expression of cyclic GMP-AMP synthase (cGAS), STING and NF-κB were higher than PDCD1 (PD-1) in DCs (Fig.3B, 3C). Compared with DC, although STING and PD-L1 were hardly expressed in B cells, NF-κB and pyroptotic effector (GSDMD) were partially elevated (Fig.4). In other words, GSDMD might rescue the inefficiency of PD-L1 inhibitors by inducing cell pyroptosis. Furthermore, pseudo-time analysis of B cells profiled that the expression of GSDMD gradually decreased over time (Fig.5).
Conclusion
Our study firstly profiles the features of STING and its downstream molecules in BM cells of B-ALL at a single cell resolution. Activation of STING is expected to be an effective approach in the treatment of B-ALL in the future.
Keyword(s): B cell acute lymphoblastic leukemia, Bone Marrow
Abstract: EP334
Type: E-Poster Presentation
Session title: Acute lymphoblastic leukemia - Biology & Translational Research
Background
B-cell acute lymphoblastic leukemia (B-ALL) is an aggressive type of acute leukemia. Despite the high complete remission (CR) rate following first-line therapy, treatment refractoriness and frequent recurrence are remained to be solved. Immunotherapy and targeted therapy have been confirmed as the effective approach for refractory and relapse (r/r) B-ALL. Although immunotherapy has achieved higher complete remission rate, remission stage can be destroyed by genomic heterogeneity and instability. Mechanistically, the occurrence of r/r B-ALL not only relied on intrinsic properties of malignant leukemic cells, but also on extrinsic protective environment provided by the tumor microenvironment (TME), especially bone marrow (BM) TME.
Aims
To clarify the transcriptome patterns in BM cells of B-ALL, single cell RNA sequencing (scRNA-seq) data was performed to be analyzed.
Methods
ScRNA-seq data of BM cells from 3 B-ALL patients were obtained from the Gene Expression Omnibus (GEO, GSE130116). Raw data was firstly processed by Seurat package. After quality control and data normalization, variable genes were extracted for dimensionality reduction. Principal component analysis (PCA) and t-distributed stochastic neighbor embedding (t-SNE) were then executed to cluster cells, following with cell types’ classification. To determine the features of cell subgroups, B cell and dendritic cell (DC) were isolated respectively and followed with gene expression analysis. Finally, pseudo-time analysis functioned by Monocle package was performed to display cell development trajectory and gene expression features over time.
Results
Based on cell clustering, 9 cell types were profiled in B-ALL BM, including naïve and memory CD4+ T cell, CD14+ monocyte, B cell, CD8+ T cell, FCGRA3+monocyte, nature killer (NK) cell, DC, and platelet (Fig.1A). Top 10 marker genes in each cell cluster were exhibited in heat map, demonstrating an effective cell classification (Fig.1B). Differential gene analysis further revealed that PD-L1 (CD274) was hardly expressed on BM cells while TMEM173 (STING), NFKB1 (NF-κB) were widespread, especially on immune cells (Fig.2A). In particular, elevation of STING and NF-κB indicated that BM cells were sensitive to the type I innate immune response rather than PD-1 mediated response (Fig.2B).
Previous studies had revealed that immune cells activation and tumor cell pyroptosis could be induced by STING. To analyze the features of STING and its downstream molecules in B-ALL BM cells, DCs and B cells were isolated from total cells respectively. DCs were separated into 3 subtypes, including monocyte derived DC, CD1C-CD14-DC and myeloid conventional DC (Fig.3A). Gene expression analysis confirmed that the expression of cyclic GMP-AMP synthase (cGAS), STING and NF-κB were higher than PDCD1 (PD-1) in DCs (Fig.3B, 3C). Compared with DC, although STING and PD-L1 were hardly expressed in B cells, NF-κB and pyroptotic effector (GSDMD) were partially elevated (Fig.4). In other words, GSDMD might rescue the inefficiency of PD-L1 inhibitors by inducing cell pyroptosis. Furthermore, pseudo-time analysis of B cells profiled that the expression of GSDMD gradually decreased over time (Fig.5).
Conclusion
Our study firstly profiles the features of STING and its downstream molecules in BM cells of B-ALL at a single cell resolution. Activation of STING is expected to be an effective approach in the treatment of B-ALL in the future.
Keyword(s): B cell acute lymphoblastic leukemia, Bone Marrow