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,
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 , its effects on the expressions of TM and TF were investigated.
Methods: NB4 cells derived from APL were incubated with 1ՌM 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.

Keywords: Auranofin, Thrombomodulin, Tissue factor, Coagulopathy, Acute promyelocytic leukemia