Inhibition of leucine aminopeptidase 3 suppresses invasion of ovarian cancer cells through down-regulation of fascin and MMP-2/9.

Leucine aminopeptidase 3 (LAP3) is a cell surface aminopeptidase that catalyzes the hydrolysis of leucine residues from the amino termini of protein or peptide substrates. The over-expression of LAP3 correlates with prognosis and malignant development of several human cell carcinomas. However, the molecular mechanism remains unknown. In this study, we used ES-2 ovarian cancer cell line as a model system to explore the role of LAP3 in regulation of cancer cell invasion by employing a natural LAP3 inhibitor bestatin and LAP3 siRNA. Bestatin inhibited tumor cell migration and invasion in a dose-dependent manner. More interestingly, bestatin down-regulated expression of fascin protein and inhibited activity of fascin promoter luciferase reporter. Both proteome profiler array and Western blot assay showed that bestatin up-regulated the phosphorylation of Hsp27. Furthermore, LAP3 siRNA could up-regulate the phosphorylation of Hsp27 and down-regulate the expression of fascin. Meanwhile, LAP3 siRNA could also down-regulate the phosphorylation of Akt and the expression of MMP-2/9. Taken together, LAP3 could affect the expression of fascin and MMP-2/9 and may act as a potential anti-metastasis therapeutic target.