Possible role of placental leucine aminopeptidase in the antiproliferative effect of oxytocin in human endometrial adenocarcinoma.
OBJECTIVE
Oxytocin (OT) was reported to inhibit the proliferation of various neoplastic tissues and cells, however, the regulation system remains unclear. This study examined the role of OT and its regulatory ability in endometrial adenocarcinoma.


METHODS
To investigate the possible function of placental leucine aminopeptidase (P-LAP) in endometrial adenocarcinoma, we transfected P-LAP cDNA into A-MEC cells, showing the lowest enzyme activity of P-LAP. Also we examined P-LAP protein expression in human endometrial adenocarcinoma.


RESULTS
We demonstrated the presence of P-LAP, which is identical to cystine aminopeptidase as oxytocinase, in human endometrial adenocarcinoma tissues and found that the expression of P-LAP increase with advances in the grade. Exposure of endometrial adenocarcinoma cell lines to OT caused dose- and time-dependent inhibition of growth. Treatment with 10(-7) M OT for 72 h reduced cell growth by 62, 25, and 30% in A-MEC, HEC1A, and Ishikawa cells, respectively. P-LAP-transfectant cells not only partially recovered from OT-induced growth inhibition but also showed a higher growth rate than parental cells under condition without OT. An OT receptor antagonist and a protein kinase A inhibitor blocked OT-induced growth inhibition in A-MEC and A-MEC-pc cells but not in A-MEC-LAP cells.


CONCLUSIONS
These findings suggested that P-LAP might be functionally positive on carcinoma cell growth by degrading suppressive peptides such as OT.
Suzuki
Yuka
Y
Department of Obstetrics and Gynecology, Nagoya Graduate University School of Medicine, Nagoya 466-8850, Japan.
Shibata
Kiyosumi
K
Kikkawa
Fumitaka
F
Kajiyama
Hiroaki
H
Ino
Kazuhiko
K
Nomura
Seiji
S
Tsujimoto
Masafumi
M
Mizutani
Shigehiko
S
D000230:Adenocarcinoma / Q000378:metabolism*; D015153:Blotting, Western; D002455:Cell Division; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D010122:Cystinyl Aminopeptidase / Q000096:biosynthesis / Q000502:physiology*; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D016889:Endometrial Neoplasms / Q000378:metabolism*; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D010121:Oxytocin / Q000502:physiology*; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014162:Transfection
D018076:DNA, Complementary; D010455:Peptides; D010121:Oxytocin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D010122:Cystinyl Aminopeptidase; C105964:leucyl-cystinyl aminopeptidase