Aminopeptidase N regulated by zinc in human prostate participates in tumor cell invasion.
Aminopeptidase N (AP-N) degrades collagen type IV and is proposed to play a role in tumor invasion. However, the precise functions of AP-N in tumor cells and the relationship of AP-N to prostate cancer remains unclear. In our study, we examined a possible role for zinc in the regulation of AP-N enzymatic activity in relation to tumor cell invasion in human prostate. AP-N purified from human prostate was irreversibly inhibited by low concentrations of zinc (Ki = 11.2 microM) and bestatin. AP-N, which has zinc in the active center, was also inhibited by the chelating agents, EDTA, o-phenanthroline and EGTA. EDTA was shown to remove zinc from the enzyme. When the effects of zinc and bestatin on invasion of PC-3 cells were investigated in vitro using a Transwell cell-culture chamber, zinc and bestatin effectively suppressed cell invasion into Matrigel at the concentration range of 50-100 microM. These results strongly suggest that the suppression of PC-3 cell invasion by zinc is based on the inhibition of AP-N activity by zinc. We also evaluated the expression of AP-N to investigate the relationship with the progression of prostate disease in human cancerous prostate. AP-N was found to be located at the cytoplasmic membranes of prostate gland epithelial cells and to be expressed more in prostate cancer, while the expression of prostate-specific antigen (PSA), which is a useful marker for prostate cancer, was shown in normal and cancer tissues, suggesting that AP-N is potentially a good histological marker of prostate cancer. Thus, highly expressed AP-N in human cancerous prostate probably plays an important role in the invasion and metastasis of prostate cancer cells.
Laboratory of Pharmaceutics, Gifu Pharmaceutical University, Gifu, Japan.
K
K
Ishii
S
S
Usui
Y
Y
Sugimura
S
S
Yoshida
T
T
Hioki
M
M
Tatematsu
H
H
Yamamoto
K
K
Hirano
D000595:Amino Acid Sequence; D018826:CD13 Antigens / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003300:Copper / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004492:Edetic Acid / Q000494:pharmacology; D004533:Egtazic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004848:Epithelium / Q000201:enzymology; D006801:Humans; D007150:Immunohistochemistry; D007930:Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D008297:Male; D009361:Neoplasm Invasiveness; D010446:Peptide Fragments / Q000737:chemistry; D010618:Phenanthrolines / Q000494:pharmacology; D011467:Prostate / Q000201:enzymology*; D011470:Prostatic Hyperplasia / Q000201:enzymology; D011471:Prostatic Neoplasms / Q000201:enzymology* / Q000473:pathology*; D013379:Substrate Specificity; D014407:Tumor Cells, Cultured; D015032:Zinc / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D010618:Phenanthrolines; D004533:Egtazic Acid; D003300:Copper; D004492:Edetic Acid; D018826:CD13 Antigens; D007930:Leucine; C012211:ubenimex; D015032:Zinc; C025205:1,10-phenanthroline