Portal de Periódicos da CAPES

Induction of cyclooxygenase-1 in a human megakaryoblastic cell line (CMK) differentiated by phorbol ester

1997; Elsevier BV; Volume: 1344; Issue: 1 Linguagem: Inglês

10.1016/s0005-2760(96)00131-2

1879-145X

Natsuo Ueda, Rieko Yamashita, Shozo Yamamoto, Kazunori Ishimura,

Estrogen and related hormone effects

Human megakaryoblastic cells (CMK line) are known to differentiate to mature megakaryocyte-like cells by treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA). There are two isozymes of prostaglandin-forming cyclooxygenase enzyme. Constitutive cyclooxygenase-1 and inducible cyclooxygenase-2 were followed during differentiation of CMK cells. Treatment of the cells with 0.1 μM TPA for 4 days resulted in a 5–20-fold increase in cyclooxygenase activity. Northern and Western blot analyses revealed that cyclooxygenase-1 mRNA and protein increased in parallel with the enzyme activity. In contrast, cyclooxygenase-2 mRNA was detected only at 3 h. Furthermore, most of the increased cyclooxygenase activity was immunoprecipitated with anti-cyclooxygenase-1 antibody, and was not affected by a cyclooxygenase-2-specific inhibitor, NS-398. These results indicated that cyclooxygenase-1 rather than cyclooxygenase-2 was predominantly induced depending on TPA. The enzyme thus induced was localized by immunoelectron microscopy in nuclear envelope and endoplasmic reticulum of the CMK cells.