It was postulated that the appearance of TM with cofactor activity in neutrophilic cells differentiated from leukemic cells may contribute to prevention of vascular thrombosis in differentiation therapy of patients with acute promyelocytic leukemia by ATRA.
The expressions of thrombomodulin (TM) and tissue factor (TF) by all-trans retinoic acid (ATRA) were studied in human leukemic cell lines including NB4 (acute promyelocytic leukemia) and U937 (monoblastic leukemia).
A relatively wide range of 9-cis RA concentrations (0.01 to 1 mumol/L) compared with ATRA was optimal for prolongation of normal plasma-based recalcification time (reduction of cell surface TF activity), decrease of TF antigen, and increase of TM antigen on the surface and in the lysates of NB4 and U937 cells.
We recently found that retinoic acids (RAs) exert anticoagulant effects by upregulating thrombomodulin (TM) and downregulating tissue factor (TF) expression in acute promyelocytic leukemia (APL) cells and monoblastic leukemia cells.
Thrombomodulin (TM) or tissue factor (TF) transcription of mRNA of freshly isolated bone marrow blast from APL patients was detected by semi-quantitative RT-PCR.