Induction of hematopoietic prostaglandin D synthase in human megakaryocytic cells by phorbol ester

Prostaglandin (PG) D synthase activity was found in the four human megakaryocytic cell lines CMK86, CMK, CMK11.5, and Dami cells. The PGD synthase in these cells was identified to be the hematopoietic-type and not the lipocalin-type, as judged by a GSH requirement for the enzyme activity, its immunoreactivity, and Northern blot analysis. The PGD synthase activity and the mRNA level of these cells increased 2.5 approximately 4.5- and 1.7 approximately 4.5-fold respectively when treated with 12-O-tetradecanoyl-phorbol-13-acetate at 0.1 microM for 72 h, indicating that the enzyme was inducible. The expression level of the enzyme was the highest in CMK86 cells and was less in CMK, CMK11-5, and Dami cells in that order. On the other hand, the expression of platelet glycoprotein Ib (CD42b), a marker of megakaryocytic maturation, was observed in those cell lines in the reverse order. These results suggest that hematopoietic PGD synthase is a useful marker for identifying the differentiation stage of human megakaryocytes.