Project description:Immunoglobulin light-chain amyloidosis (AL) is a rare clonal plasma cell (PC) disorder that remains largely incurable. AL and multiple myeloma (MM) share the same cellular origin, but while knowledge about MM PC biology has improved significantly, the same does not apply for AL. Here, we undertook an integrative phenotypic, molecular, and genomic approach to study clonal PCs from 22 newly-diagnosed AL patients. Through principal-component-analysis, we demonstrated highly overlapping phenotypic profiles between AL and MGUS or MM patients. However, in contrast to MM, highly-purified FACSs-sorted clonal PCs in AL (n=9/22) show virtually normal transcriptomes with only 68 deregulated genes as compared to normal PCs, including a few tumor suppressor (CDH1, RCAN) and pro-apoptotic (GLIPR1, FAS) genes. Notwithstanding, clonal PCs in AL (n=11/22) were genomically unstable with a median of 9 copy-number-abnormities (CNAs) per case; many of which similar to those found in MM. Whole-exome sequencing (WES) was performed in three AL patients and revealed a median of 10 non-recurrent mutations per case. Altogether, we showed that although clonal PCs in AL display phenotypic and CNA profiles similar to MM, their transcriptome is remarkably similar to that of normal PCs. First-ever WES revealed the lack of a unifying mutation in AL A total of 22 patients with confirmed diagnosis of AL based on the presence of amyloid-related systemic syndrome, positive amyloid tissue staining with Congo red, and evidence of PC clonality were studied. Samples were collected after informed consent was given, in accordance with local ethical committee guidelines and the Helsinki Declaration. GEP was performed in 9/22 AL cases with adequate RNA extracted from FACS-purified clonal PCs according to patient-specific aberrant phenotypes, and compared to that of normal PCs from 5 healthy individuals (FACSAriaIIb, BDB; â¥95% purity). RNA was hybridized to the Human Gene 1.0 ST Array (Affymetrix, Santa Clara, CA, USA) and normalization was carried using the expression console (Affymetrix) with the RMA algorithm which includes background correction, normalization and calculation of expression values (log2). Differentially expressed genes between classes were identified using the Significant Analysis of Microarrays (SAM) algorithm (http://www-stat.standford.edu/-tibs/SAM), and significant genes were selected based on the lowest q-value (<10-5).

Project description:Immunoglobulin light-chain amyloidosis (AL) is a rare clonal plasma cell (PC) disorder that remains largely incurable. AL and multiple myeloma (MM) share the same cellular origin, but while knowledge about MM PC biology has improved significantly, the same does not apply for AL. Here, we undertook an integrative phenotypic, molecular, and genomic approach to study clonal PCs from 22 newly-diagnosed AL patients. Through principal-component-analysis, we demonstrated highly overlapping phenotypic profiles between AL and MGUS or MM patients. However, in contrast to MM, highly-purified FACSs-sorted clonal PCs in AL (n=9/22) show virtually normal transcriptomes with only 68 deregulated genes as compared to normal PCs, including a few tumor suppressor (CDH1, RCAN) and pro-apoptotic (GLIPR1, FAS) genes. Notwithstanding, clonal PCs in AL (n=11/22) were genomically unstable with a median of 9 copy-number-abnormities (CNAs) per case; many of which similar to those found in MM. Whole-exome sequencing (WES) was performed in three AL patients and revealed a median of 10 non-recurrent mutations per case. Altogether, we showed that although clonal PCs in AL display phenotypic and CNA profiles similar to MM, their transcriptome is remarkably similar to that of normal PCs. First-ever WES revealed the lack of a unifying mutation in AL A total of 22 patients with confirmed diagnosis of AL based on the presence of amyloid-related systemic syndrome, positive amyloid tissue staining with Congo red, and evidence of PC clonality were studied. Samples were collected after informed consent was given, in accordance with local ethical committee guidelines and the Helsinki Declaration. Genome-wide detection of CNAs and copy-number neutral loss-of-heterozygosity (LOH) were investigated using the Cytoscan 750K platform (Affymetrix) in 11/22 cases with adequate DNA extracted from FACS-sorted clonal PCs and paired T-lymphocytes. The AGCC and ChAS software programs (Affymetrix) were used for data analysis as described elsewhere. CNAs were reported when the three following criteria were met: â¥25 consecutive imbalanced markers per segment; â¥100Kb minimum genomic size and; <50% overlap with paired control DNA and/or genomic variants of Toronto DB (DGV). Only CNN-LOH larger that 5Mb, with â¥25 consecutive imbalanced markers per segment, and <50% overlap with patient-paired CNAs were considered.

Project description:Amyloid light chain amyloidosis (AL) is an incurable protein misfolding disorder characterized by the production of amyloidogenic immunoglobulin light chains by clonal populations of plasma cells. These abnormal light chains accumulate as amyloid fibrils in vital organs and cause multi-organ dysfunction that can be rapidly fatal. Current treatment regimens, which include proteasome inhibitors, were developed for the treatment of the more common plasma cell disease multiple myeloma and have demonstrated efficacy in AL amyloidosis. However, use of these agents is frequently limited due to multi-organ dysfunction at presentation, resulting in a median survival of 2-3 years and underscoring the need for novel therapies. By analyzing bone marrow-derived plasma cells from 44 patients with AL amyloidosis, we find that clonal plasma cells are highly primed to undergo apoptosis and exhibit strong dependencies on pro-survival BCL-2 family proteins that can potentially be targeted by recently-developed BH3 mimetics. In particular, we find that clonal plasma cells are highly dependent on the pro-survival MCL-1 and undergo apoptosis in response to single-agent treatment with an MCL-1 inhibitor. Notably, this MCL-1 dependency is indirectly targeted by the proteasome inhibitor bortezomib, which is currently the standard of care for this disease, via the stabilization of Noxa and its direct inhibitory binding to MCL-1. BCL-2 inhibition with the FDA-approved inhibitor venetoclax (ABT-199) sensitizes plasma cells to bortezomib treatment and other front-line therapies, which can be observed in vitro and in vivo. Mass spectrometry-based proteomic analysis reveals changes in signaling pathways regulating apoptosis, proliferation and mitochondrial metabolism between isogenic AL amyloidosis and multiple myeloma cells that divergently alter their sensitivity to therapy. Overall, our results indicate that BH3 mimetics may be highly effective therapies for AL amyloidosis that exploit inherent and induced dependencies on pro-survival proteins.

Project description:Light chain amyloidosis (AL) is a life-threatening plasma cell dyscrasia manifested by irreversible damage of multiple organs caused by monoclonal immunoglobulin light chain, production of pathogenic bone marrow plasma cells (BMPCs). Although AL is featured by both misfolding of monoclonal protein and plasma cell proliferation, the functional subclones and molecular mechanism of BMPCs in AL remain elusive. Also, inter-individual heterogeneities of AL determine the chemotherapy response and organ tropism of light chains, which require well-defined molecular subtypes. To address these, we conducted single-cell RNA sequencing (scRNA-seq) of BMPCs donated by patients with AL, patients with monoclonal gammopathy of undetermined significance (MGUS), and healthy controls. Single-cell transcriptome revealed a continuity of bone marrow plasma cell (BMPC) functional subclones, delineating DNA repair, cell proliferation, immunoglobulin production, etc., with the gradient of signaling entropy and immunoglobulin production. The amyloidosis-associated genes, such as the amyloid-beta binding Apolipoprotein E (APOE), Cystatin 3 (CST3), and Complement C1q A Chain (C1QA), were up-regulated in a subclone enriched in AL. The speculated light chain-producing subclones in AL up-regulated neutrophil degranulation pathways, transport to and modifications in Golgi apparatus, and asparagine N-linked protein glycosylation. Cyclin D1 (CCND1)hi AL, consisted of larger main subclones which highly expressed Bcl-2 complex and B-cell differentiation genes, was sensitive to venetoclax that targets Bcl-2. A major subset of CCND1low AL harbored larger carbohydrate-synthesizing subclone and up-regulated CCND2 and the amyloidosis-associated genes. Collectively, our results provided frontier insights into the functional subclones and molecular mechanism of BMPCs in AL, associated with amyloidosis, light chain production and venetoclax sensitivity, as knowledge for the future research on AL pathogenesis, AL subtypes and AL-specific therapies.

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Phenotypic, transcriptomic and genomic characterization of clonal plasma cells in light chain amyloidosis

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