Abstract
We have recently reported that retinoic acid (RA) induced the expression of trkA, the high affinity receptor for nerve growth factor (NGF), in human myeloid leukemia KG-1 cells. In the present study, we report that the expression of trkA was also induced by several other differentiation inducers, including lα, 25-dihydroxyvitamin D3 (Vit D3), l-β-D-arabinofura-nosyl cytosine (Ara-C), sodium butyrate (NaBut), and phorbol 12-myristate 13-acetate (PMA). Interestingly, RA in combination with NaBut or PMA synergistically induced cellular differentiation as well as the expression of trkA in KG-1 cells. Furthermore, activation of the induced trk A receptor by exogenous NGF potentiated the differentiating effects of RA and NaBut. Our results demonstrated that the induction of trkA is an event associated with the differentiation of KG-1 cells. Our findings suggest that NGF, in addition to its pivotal roles in the nervous system, may also play important roles in hematopoietic differentiation.