SUSTAINED C-KIT EXPRESSION IN A HUMAN ERYTHROLEUKEMIA CELL-LINE (HEL) AFTER MEGAKARYOCYTIC DIFFERENTIATION-INDUCED BY 12-O-TETRADECANOYLPHORBOL-13-ACETATE (TPA)

Changes in c-kit proto-oncogene expression were examined in a human erythroleukemia cell line, HEL, during 12-0-tetradecanoylphorbol 13-acetate (TPA)-induced megakaryocytic differentiation. When HEL cells were treated with 10(-7) M TPA, glycophorin A expression and hemoglobin synthesis were reduced, while the expression of GP IIb/IIIa was induced in association with the morphological changes. Northern blot analysis showed that, during this megakaryocytic differentiation of HEL cells, c-kit mRNA expression persisted even after there was an apparent reduction in c-myc mRNA. This finding supports the idea that the expression of c-kit, a marker of primitive hematopoietic progenitors, may persist along with differentiation toward a megakaryocytic lineage.