EXPRESSION OF THE NERVE GROWTH-FACTOR RECEPTOR C-TRK IN HUMAN MYELOID-LEUKEMIA CELLS

Nerve growth factor (NGF) is of major importance for the survival, dev elopment and maintenance of peripheral sympathetic and central neurona l tissue. Most of the cellular effects are mediated by binding to thei r high-affinity receptor c-TRK. a transmembrane receptor tyrosine kina se. C-TRK protein has been detected in neuronal tissue and also in mas t cells, monocytes and some haemopoietic progenitor cells. Here we rep ort c-TRF; 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 ind ucible by differentiation induction with tetradecanoyl-phorbol 13-acet ate (TPA). In c-TRK gene-expressing cells the transmembrane receptor t yrosine kinase was detectable by Western blotting and by in vitro kina se assay. In the AML group, c-TRK expression was not correlated to the FAB-classified morphology or any other clinical parameter. In all cas es tested we could not detect NGF mRNA by means of reverse transcripta se PCR, excluding an autocrine loop involving the TRK/NGF receptor-lig and system in leukaemogenesis. Our results show another example of pos sible communication between neuronal and haemopoietic tissue. However, we still lack positive evidence of a c-TRK function in haemopoiesis.