Expression of the nerve growth factor receptor c‐TRK in human myeloid leukaemia cells

Nerve growth factor (NGF) is of major importance for the survival, development and maintenance of peripheral sympathetic and central neuronal tissue. Most of the cellular effects are mediated by binding to their high-affinity receptor c-TRK, a transmembrane receptor tyrosine kinase. C-TRK protein has been detected in neuronal tissue and also in mast cells, monocytes and some haemopoletic progenitor cells. Here we report c-TRK gene expression in myeloid leukaemic cell lines (HEL, K562 and KG-1) and for the first time in the primary leukaemic cells of 44% (n = 59) of patients with acute myelogenous leukaemia (AML). Moreover, in the human promyelocytic cell line HL-60, c-TRK expression was inducible by differentiation induction with tetradecanoyl-phorbol 13-acetate (TPA). In c-TRK gene-expressing cells the transmembrane receptor tyrosine kinase was detectable by Western blotting and by in vitro kinase assay. In the AML group, c-TRK expression was not correlated to the FAB-classified morphology or any other clinical parameter. In all cases tested we could not detect NGF mRNA by means of reverse transcriptase PCR, excluding an autocrine loop involving the TRK/NGF receptor-ligand system in leukaemogenesis. Our results show another example of possible communication between neuronal and haemopoietic tissue. However, we still lack positive evidence of a c-TRK function in haemopoiesis.