Autocrine motility factor enhances hepatoma cell invasion across the basement membrane through activation of β1 integrins

Abstract

Autocrine motility factor/phosphohexose isomerase (AMF/PHI) is a cytokine that is linked to tumor invasion and metastasis. In hepatocellular carcinoma (HCC) tissues, hepatoma cells produce AMF/PHI and its receptor, Mr 78,000 glycoprotein (gp78), is strongly detected in hepatoma cells invading into the stroma and tumor thrombi in the portal vein. Here, we investigated the mechanism of hepatoma cell invasion through Matrigel induced by AMF/PHI using 3 hepatoma cell lines. Production of AMF/PHI, phosphorylation of MEK1/2, and Rho activity were investigated by immunoblotting. Expression of AMF/PHI and gp78 was observed by confocal fluorescence microscopy. The influence of AMF/ PHI on activated integrin ␤1 subunit expression was evaluated by flow cytometry. Changes in invasion, adhesion, and motility induced by AMF/PHI were evaluated using chemoinvasion, adhesion, and phagokinetic track motility assays. The invasive and metastatic potential of tumor cells is a major feature of malignancy. The process of tumor metastasis and invasion consists of a series of complex events that includes the following steps: 1) detachment of tumor cells from the primary site; 2) migration into the lymphatic or vasculature; 3) arrest at distant sites via interactions with vascular or lymphatic endothelial cells; 4) migration into tissue parenchyma; and 5) growth at the metastatic site. 1 During this process, tumor cells must migrate to, attach to, and penetrate the basement membrane. 2 Integrins and matrix metalloproteinases (MMPs) are both involved in this step. There is growing evidence that destruction of the basement membrane by tumor cells is a prerequisite for tumor metastasis and invasion. 3,4 Therefore, studies that elucidate mechanisms of tumor cell invasion through the basement membrane should enhance our understanding of tumor progression and are of clinical significance.

Overexpression of autocrine motility factor in metastatic tumor cells: possible association with augmented expression of KIF3A and GDI-β

“…AMF/PHI also stimulates MMP-2 secretion and extracellular MMP-2 activation, being related to destruction of the basement membrane followed by metastasis and invasion in hepatoma cells. 32 These mechanisms occurring in host organs also may contribute to AMF-regulated dissemination of tumor cells.…”

“…30 Interestingly, transfection of AMF/PHI-tagged hemagglutinin into Cos7 cells reveals its intracellular localization within actin-rich pseudopodial domains. 31 Torimura et al 32 have demonstrated that AMF/PHI enhances Rho activity and phosphorylation of MEK1 and MEK2 in human hepatoma cell lines. Rho is one of the most important molecules in the AMF/PHI signal transduction.…”

Tracing Putative Trafficking of the Glycolytic Enzyme Enolase via SNARE-Driven Unconventional Secretion

“…Therefore, enolase is a therapeutic target for many diseases, including candidiasis (7,55). Another extracellular glycolytic enzyme, phosphoglucose isomerase, enhances the motility of tumor cells (11) and performs like a cytokine (52), although it possesses no enzymatic activity outside the cell (54). However, the secretory pathway of glycolytic enzymes such as enolase and phosphoglucose isomerase remains to be revealed.…”

Novel roles of the autocrine motility factor/phosphoglucose isomerase in tumor malignancy

“…C3 exoenzyme inhibited stress fiber formation accompanied by a decrease in active RhoA, indicating that AMFinduced cytoskeletal rearrangement is dependent on Rho activation. Torimura et al (2001) also demonstrated that, in human hepatoma cell lines, AMF/PGI enhanced Rho activity, which was slightly blocked by the functionblocking antibody for the integrin-b1 subunit.…”