AMF/G6PI induces differentiation of leukemic cells via an unknown receptor that differs from gp78.

Autocrine Motility Factor (AMF)/maturation factor (MF)/neuroleukin (NLK) is a multifunctional protein, which acts as a glucose 6-phosphate isomerase (G6PI) intracellularly. Exto-G6PI stimulates invasion and metastasis of tumor cells, neurotropic growth and differentiation of leukemic cells. The cell motility and proliferation receptor is known to be gp78 (78 kilo-Dalton glycoprotein), which has seven transmembrane domains in its N-terminal region, but the maturation factor receptor remains unclear. The human acute monocytic leukemia line does not express gp78 and its motile activity is not enhanced by AMF though it is well differentiated by AMF exposure. The forced expression of gp78 in leukemic cells recovered acceptable motile stimulation, concomitant with reduced differentiation ability. Two unknown proteins were detected by crosslinking between AMF and leukemic cells. The results of this report suggest that the receptor molecule for AMF/NLK/MF in leukemic differentiation is not gp78.