Phosphoglucose isomerase/autocrine motility factor (PGI/AMF) catalyzes the isomerization between glucose-6-phosphate and fructose-6-phosphate, and is involved in cytokine activity, mitogenesis, differentiation, oncogenesis, and tumor metastasis. Presently, we demonstrate that exogenous PGI/AMF stimulates the migration of Huh7 and HepG2 hepatoma cells, but not Hep3B cells. Inhibition of PGI/AMF by PGI/AMF specific inhibitor 5-phospho-D-arabinonate markedly repressed the cellular migration. RTPCR was used to examine the expression profile of matrix metalloproteinases (MMPs). MMP-3 transcripts, protein level, and secreted form were significantly upregulated in PGI/AMF-treated Huh7 and HepG2 cells, but not in Hep3B cells. MMP-3 inhibition abolished the PGI/AMF-induced cell motility. The observations are consistent with a downstream mediation role of MMP-3 in PGI/ AMF-stimulated tumor cell metastasis. (C) 2003 Elsevier Inc. All rights reserved.