endothelin-1 and Leukemia--Megakaryoblastic--Acute

The aim of the present investigation was to determine whether endothelin (ET) could be expressed in and released from the human leukemia megakaryoblastic cell lines HEL, MEG-01, DAMI and the normal human platelet progenitors. Using the reverse transcriptase-polymerase chain reaction (RT-PCR) on total RNA isolated from the cells, we amplified a cDNA of the expected size (453 bp). Southern-blotting hybridization revealed that RT-PCR products from the cell lines were specific of ET-1 mRNA. Immunocytochemical analyses highlighted immunoreactive ET-1 in the cytoplasm of these cells which also released the mature peptide. ET-1 release from the three cell lines was increased by thrombin exposure. Although MEG-01 cells express ET receptors, ET-1, the selective ETB agonist sarafotoxin 6C and the non-selective ET-receptor antagonist PD 142893 showed no proliferative or antiproliferative action in basal or stimulating medium. This indicated a lack of autocrine ET-mediated effect on growth. These results demonstrate for the first time that human megakaryoblastic leukemia cell lines and normal bone marrow platelet precursors express ET-1 mRNA and release the mature peptide.

Topics: Blood Platelets; Blotting, Southern; Cell Division; Endothelin Receptor Antagonists; Endothelin-1; Gene Expression; Hematopoietic Stem Cells; Humans; Immunohistochemistry; Leukemia, Megakaryoblastic, Acute; Megakaryocytes; Oligopeptides; Polymerase Chain Reaction; Receptor, Endothelin A; Receptor, Endothelin B; Receptors, Endothelin; RNA, Messenger; Thrombin; Tumor Cells, Cultured; Viper Venoms