Thrombospondin-1 (TSP-1) in primary myelofibrosis (PMF) - a megakaryocyte-derived biomarker which largely discriminates PMF from essential thrombocythemia
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Michaela Muth1, Bianca M Engelhardt, Nicolaus Kröger
1Institute of Pathology, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
Abstract:
Primary myelofibrosis (PMF) is a chronic myeloproliferative neoplasm showing aberrant bone marrow remodeling with increased angiogenesis, progressive matrix accumulation, and fibrosis development. Thrombospondins (TSP) are factors sharing pro-fibrotic and anti-angiogenic properties, and have not been addressed in PMF before. We investigated the expression of TSP-1 and TSP-2 in PMF related to the stage of myelofibrosis (n = 51) and in individual follow-up biopsies by real-time PCR, immunohistochemistry, and confocal laser scanning microscopy (CLSM). TSP-1 was significantly overexpressed (p < 0.05) in all stages of PMF when compared to controls. Individual follow-up biopsies showed involvement of TSP-1 during progressive myelofibrosis. TSP-2 was barely detectable but 40% of cases with advanced myelofibrosis showed a strong expression. Megakaryocytes and interstitial proplatelet formations were shown to be the relevant source for TSP-1 in PMF. Stroma cells like endothelial cells and fibroblasts showed no TSP-1 labeling when double-immunofluorescence staining and CLSM were applied. Based on its dual function, TSP-1 in PMF is likely to be a mediator within a pro-fibrotic environment which discriminates from ET cases. On the other hand, TSP-1 is a factor acting (ineffectively) against exaggerated angiogenesis. Both features suggest TSP-1 to be a biomarker for monitoring a PMF-targeted therapy.
Insights
Thrombospondin-1 (TSP-1) is overexpressed in primary myelofibrosis (PMF), a bone marrow disorder. This finding suggests TSP-1 may serve as a biomarker for monitoring PMF therapies.
Area of Science:
- Hematology
- Oncology
- Molecular Biology
Background:
- Primary myelofibrosis (PMF) is a chronic myeloproliferative neoplasm characterized by bone marrow remodeling, fibrosis, and angiogenesis.
- Thrombospondins (TSPs) possess pro-fibrotic and anti-angiogenic properties, but their role in PMF remains unexplored.
Purpose of the Study:
- To investigate the expression and cellular sources of TSP-1 and TSP-2 in PMF.
- To correlate TSP expression with myelofibrosis staging and disease progression.
Main Methods:
- Real-time PCR, immunohistochemistry, and confocal laser scanning microscopy (CLSM) were used to analyze TSP-1 and TSP-2 expression.
- Study included 51 PMF patients and analyzed individual follow-up biopsies.
Main Results:
- TSP-1 was significantly overexpressed in all stages of PMF compared to controls.
- TSP-1 expression increased during myelofibrosis progression, originating from megakaryocytes and proplatelet formations.
- TSP-2 was minimally detected, with strong expression in 40% of advanced PMF cases.
Conclusions:
- TSP-1 is a key mediator in the pro-fibrotic environment of PMF and acts against excessive angiogenesis.
- TSP-1's dual role suggests its potential as a biomarker for monitoring PMF-targeted therapies.
