Thrombin Modulates and Reverses Neuroblastoma Neurite Outgrowth

• Published in: Proceedings of the National Academy of Sciences - PNAS 1988-05, Vol.85 (10), p.3440-3444
• Main Authors: Gurwitz, David, Cunningham, Dennis D.
• Format: Article
• Language: English
• Subjects: Alprostadil - pharmacology; Animals; Axons - drug effects; Axons - ultrastructure; Bucladesine - pharmacology; Cell biology; Cell culture techniques; Cell Line; Cells; Cellular differentiation; Clone Cells; Culture Media; Cultured cells; Heparin; Hirudins - pharmacology; Humans; Kinetics; Mice; Neurites; Neuroblastoma; Neuroblastoma - pathology; Neurons; Protease inhibitors; Thrombin - pharmacology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.85.10.3440

Previous studies have shown that neuroblastoma cells and several types of primary neuronal cells in culture rapidly extend neurites when switched from serum-containing to serum-free medium. The present studies on cloned neuroblastoma cells show that thrombin blocked this spontaneous differentiation at 2 nM with a half-maximal potency of 50 pM. This required the catalytic activity of thrombin and was reversed upon thrombin removal. Thrombin also caused cells in serum-free medium to retract their neurites at equally low concentrations. Two other serine proteases, urokinase and plasmin, did not block or reverse neurite extension even at 100-fold higher concentrations. A specific assay for thrombin indicated that thrombin detected in serum-containing medium from neuroblastoma cultures was derived from serum and that it was likely responsible for much of the known capacity of serum to maintain neuroblastoma cells in a nondifferentiated state. This was supported by the finding that heparin addition reduced the thrombin concentration in serum-containing medium and stimulated neurite outgrowth from neuroblastoma cells in serum-containing medium. Studies on the ability of thrombin to modulate neurite outgrowth by other agents showed that it blocked and reversed the neurite outgrowth activity of two thrombin inhibitors: protease nexin-1 (which is identical to glial-derived neurite-promoting factor) and hirudin. Thrombin, however, did not block the neurite-promoting activity of dibutyryl cAMP or prostaglandin E1. These results suggest a specific role for thrombin in control of neurite outgrowth.