Adenosylmethionine decarboxylase (AdoMetDC), a key enzyme in the biosynthesis of polyamines, is often up-regulated in cancers. We have demonstrated previously that overexpression of AdoMetDC alone is sufficient to transform NIH 3T3 cells and induce highly invasive tumors in nude mice. Here, we studied the transformation-specific alterations in gene expression induced by AdoMetDC by using cDNA microarray and two-dimensional electrophoresis technologies. We specifically tried to identify the secreted proteins contributing to the high invasive activity of the AdoMetDC-transformed cells. We found a significant increase in the expression and secretion of procathepsin L, which was cleaved and activated in the presence of glycosaminoglycans (heparin), and a smaller increase in cathepsin B. Inhibition of the cathepsin L and B activity by specific peptide inhibitors abrogated the invasive capacity of the AdoMetDC transformants in Matrigel. The transformed cells also showed a small increase in the activity of gelatin-degrading matrix metalloproteinases (MMPs) and urokinase-type plasminogen activator activities, neither of which was sensitive to the inhibitors of cathepsin L and B. Furthermore, the invasive potency of the transformed cells remained unaffected by specific inhibitors of MMPs. The results suggest that cysteine cathepsins are the main proteases contributing to the high invasiveness of the AdoMetDC-transformed cells and that the invasion potential is largely independent of activation of the MMPs.

Trichinella spiralis and Trichinella nativa are both common wildlife parasites in Finland. However, they differ substantially in their resistance to below 0 degrees C temperatures in their natural hosts. T. nativa can live in frozen fox meat for years, whereas T. spiralis dies when frozen. In mouse muscle, the difference is not as evident; even T. nativa cannot maintain infectivity when kept at -20 degrees C for 1 week. Crude larval protein extracts of these two parasite species were analyzed by two-dimensional gel electrophoresis (2DE). The protein patterns showed clear differences, but matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) peptide mass fingerprint followed by database searches failed to identify these proteins, suggesting that they may still be uncharacterized. The patterns compared after freezing treatment at -20 degrees C revealed changes in the intensity of some protein spots. The antigenic differences of the species were analyzed with two-dimensional Western blots, which showed T. spiralis-specific proteins.

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