Abstract
Introduction
Multiple myeloma (MM) is a haematological cancer characterized by the accumulation of monoclonal plasma cells in the bone marrow. Despite new advancements, MM remains incurable due to drug resistance. Malignant cells can adapt their lipid metabolism to attain higher rates of proliferation and avoid chemotherapy-induced apoptosis. In this study, we aimed (1) to identify changes in lipid metabolism in MM patients, (2) to investigate this altered metabolism in vitro.
Material and Methods
A lipidomics assay was performed on plasma samples of MM patients and healthy controls. Effects of sphingomyelin and ceramide were evaluated on proliferation of human MM cell lines OPM2, U266, JJN3 and LP1. After treatment with standard-of-care (SoC) drugs melphalan and bortezomib, acid sphingomyelinase (ASM) content was measured on JJN3-derived exosomes by western blot. Exosomes were isolated by centrifugation, while exosome secretion was measured by nanoparticle tracking. Amitriptyline was used as an ASM inhibitor. Effects on apoptosis were measured by flow cytometry and western blot. To prove statistical significance, a Mann-Whitney U test was performed.
Results
Lipidomics analysis revealed an upregulation of ceramides and downregulation of sphingomyelin in MM patients, leading to the conclusion that ASM, which transforms sphingomyelin into ceramide, is upregulated in MM patients. We confirmed this on bone marrow samples, comparing CD138+ to CD138- fractions. Addition of ceramide to MM cells increased viability, while sphingomyelin caused a decrease. ASM content was also increased in SoC-treated JJN3-derived exosomes. Furthermore, SoC drugs stimulated exosome secretion. Interestingly, amitriptyline (= ASM inhibitor, often prescribed in MM patients for neuropathic pain) increased the efficacy of both drugs on cell lines by activating PARP and caspase 3 pathways. Combination therapy was also successfully tested on primary MM samples.
Conclusion
SoC drugs increase ASM in primary MM cells, cell lines and their exosomes. Amitriptyline-based inhibition of ASM increases drug efficacy.
Multiple myeloma (MM) is a haematological cancer characterized by the accumulation of monoclonal plasma cells in the bone marrow. Despite new advancements, MM remains incurable due to drug resistance. Malignant cells can adapt their lipid metabolism to attain higher rates of proliferation and avoid chemotherapy-induced apoptosis. In this study, we aimed (1) to identify changes in lipid metabolism in MM patients, (2) to investigate this altered metabolism in vitro.
Material and Methods
A lipidomics assay was performed on plasma samples of MM patients and healthy controls. Effects of sphingomyelin and ceramide were evaluated on proliferation of human MM cell lines OPM2, U266, JJN3 and LP1. After treatment with standard-of-care (SoC) drugs melphalan and bortezomib, acid sphingomyelinase (ASM) content was measured on JJN3-derived exosomes by western blot. Exosomes were isolated by centrifugation, while exosome secretion was measured by nanoparticle tracking. Amitriptyline was used as an ASM inhibitor. Effects on apoptosis were measured by flow cytometry and western blot. To prove statistical significance, a Mann-Whitney U test was performed.
Results
Lipidomics analysis revealed an upregulation of ceramides and downregulation of sphingomyelin in MM patients, leading to the conclusion that ASM, which transforms sphingomyelin into ceramide, is upregulated in MM patients. We confirmed this on bone marrow samples, comparing CD138+ to CD138- fractions. Addition of ceramide to MM cells increased viability, while sphingomyelin caused a decrease. ASM content was also increased in SoC-treated JJN3-derived exosomes. Furthermore, SoC drugs stimulated exosome secretion. Interestingly, amitriptyline (= ASM inhibitor, often prescribed in MM patients for neuropathic pain) increased the efficacy of both drugs on cell lines by activating PARP and caspase 3 pathways. Combination therapy was also successfully tested on primary MM samples.
Conclusion
SoC drugs increase ASM in primary MM cells, cell lines and their exosomes. Amitriptyline-based inhibition of ASM increases drug efficacy.
| Original language | English |
|---|---|
| Publication status | Published - 7 Jun 2019 |
| Event | LKI-Oncoforum 2019 - Auditorium BMW6, O&N2, Gasthuisberg, Leuven, Belgium Duration: 7 Jun 2019 → 7 Jun 2019 Conference number: 16 https://www.uzleuven-kuleuven.be/lki/en/lki-oncoforum-2019 |
Conference
| Conference | LKI-Oncoforum 2019 |
|---|---|
| Country | Belgium |
| City | Leuven |
| Period | 7/06/19 → 7/06/19 |
| Internet address |