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Tumor gangliosides enhance alpha2 beta1 integrin-dependent platelet activation
1Department of Padiatrics, Rush Children's Hospital, Chicago, IL 60612-3833, USA. Ivalenti@rpslmc.edu
Biochimica Et Biophysica Acta
|May 24, 1996
Summary
Neuroblastoma-derived gangliosides (NBTG) specifically enhance collagen-mediated platelet activation by interacting with the alpha 2 beta 1 integrin receptor. This interaction boosts platelet aggregation and ATP release, highlighting a potential mechanism in tumor cell metastasis.
Area of Science:
- Biochemistry
- Oncology
- Hematology
Background:
- Gangliosides are sialic acid-containing glycosphingolipids involved in cell-cell interactions.
- Tumor-derived gangliosides, such as those from neuroblastoma cells (NBTG), can influence platelet function.
- Platelet activation is crucial in hemostasis and also implicated in tumor cell metastasis.
Purpose of the Study:
- To investigate the mechanism by which neuroblastoma-derived gangliosides (NBTG) enhance platelet activation.
- To determine if NBTG specifically affects collagen-mediated platelet responses.
- To identify the specific platelet receptor involved in NBTG-induced platelet activation.
Main Methods:
- Platelet aggregation and adenosine triphosphate (ATP) release assays were performed using NBTG and various agonists.
- The role of extracellular magnesium was assessed.
- Monoclonal antibodies against platelet collagen receptors, including alpha 2 beta 1 integrin (anti-alpha 2 chain 5E8) and CD36, were used to block NBTG effects.
- Platelet adhesion to immobilized collagen was measured.
Main Results:
- NBTG significantly enhanced platelet aggregation and ATP release induced by subthreshold collagen concentrations, but not by other agonists like ADP, epinephrine, thrombin, or arachidonic acid.
- The effect of NBTG required extracellular magnesium and a short preincubation period.
- A monoclonal antibody against the alpha 2 chain of the alpha 2 beta 1 integrin (5E8) completely blocked NBTG-induced platelet aggregation and ATP release.
- Antibodies against CD36 or isotype control antibodies did not inhibit the NBTG effect.
- NBTG and its component GD2 enhanced alpha 2 beta 1-mediated platelet adhesion to collagen in an antibody 5E8-inhibitable manner.
Conclusions:
- Neuroblastoma-derived gangliosides (NBTG) specifically potentiate collagen-mediated platelet activation.
- The alpha 2 beta 1 integrin-collagen interaction is identified as the primary target for NBTG's pro-platelet activity.
- These findings suggest a mechanism by which tumor gangliosides may promote metastasis through platelet interactions.