The Effect of Auranofin on Thrombomodulin Expression in Acute Promyelocytic Leukemia Cell

BACKGROUND: Acute promyelocytic leukemia (APL) is distinguished from other forms of leukemia by its association with bleeding diatheses. All-trans retinoic acid (ATRA) and arsenic trioxide (As2O3), which have been effectively used in the treatment of the APL, promptly improve coagulation/bleeding syndromes by regulating the expressions of tissue factor (TF) and thrombomodulin (TM). We have previously shown a novel activity of auranofin (AF), in that it induced apoptosis and differentiation of NB4 cells. To study whether AF also possesses similar anticoagulant effects to those of ATRA and As2O3, its effects on the expressions of TM and TF were investigated. METHODS: NB4 cells derived from APL were incubated with 1 micrometer of AF. After incubation for 12, 24 and 48 hours, the AF-regulated expressions of TM and TF were analyzed by RT-PCR, Northern blot and Western blot. The assay for the TM antigen on the cell surface was performed using a flow cytometry. RESULTS: The expression of the TM gene was increased for upto 12 hours after the AF treatment, but no change was observed in the expression of the TF gene. Western blot analysis also demonstrated that AF increased the level of TM proteinin a time-dependent manner. FACS data showed the TM antigen on the cell surface to gradually increase for upto 48 hours in AF-treated cells. CONCLUSION: The results of this study indicate that AF can have an antithrombotic function via the up-regulation of the expression of TM, which suggests it may partially contribute to the improvement of coagulopathies in APL.

Effects of Val34Leu and Val35Leu polymorphism on the enzyme activity of the coagulation factor XIII-A

Change in fibrin stabilizing activity of factor XIII A subunit (FXIII-A) caused by a specific mutation, Val34Leu, is recently implicated to incidences of pathophysiology of thrombosis. In an effort to understand the effect of Val34Leu on enhanced catalytic role of FXIII-A, wild type human factor XIII A (HFXIII-A) and mutant HFXIII-A: HFXIII-A (V34L), HFXIII-A (V35L) and HFXIII-A (V34L/V35L) cDNA were expressed in E.coli system where the purified recombinant FXIII-A (rFXIII-A) showed a similar specific transglutaminase activity comparable to the human native FXIII-A from platelet. Using these rFXIII-A mutants, the activation kinetics by thrombin and the enzymatic properties of the activated rFXIII-A were characterized. rFXIII-A (V34L) and rFXIII-A (V34L/V35L) mutants were activated by thrombin much faster than those of wild type rFXIII-A and V35L variant. However, the activated rFXIII-A and mutants showed the identical catalytic efficiency as measured by in vitro assay. These results suggest that ready activation caused by a specific mutation of neighboring thrombin cleavage site(s) in the activation peptide of FXIII-A like V34L resulted in the real-time amount of the activated factor XIII-A that could influence the outcome of fibrin stabilization in vivo such as alpha2- plasmin inhibitor crosslinking to fibrin, a reaction known to be dependent on the initial concentration of active factor-XIII-A.