title: A novel role for placental leucine aminopeptidase (P-LAP) as a determinant of chemoresistance in endometrial carcinoma cells.
abstract: In several recent studies, we have shown that P-LAP can be a poor prognostic factor and a factor of chemoresistance in endometrial carcinoma, especially in the advanced patients. In our study, we investigated whether P-LAP alters the expression of apoptosis regulatory proteins as a mechanism of drug resistance. We transfected P-LAP cDNA into A-MEC cells (endometrial adenocarcinoma cell line), and A-MEC-LAP cells displayed a 1.8-fold, 2.0-fold and 1.7-fold increase in IC(50) against paclitaxel, carboplatin and cisplatin respectively. Translational downregulation by siRNA2 to P-LAP on A-MEC-LAP cells demonstrated 60%, 51% and 58% decrease in IC(50). To investigate the mechanism of P-LAP-induced chemoresistance, we also assessed whether P-LAP transfection had an effect on carboplatin-induced apoptotic death of A-MEC cells. A-MEC and A-MEC-pc (transfected with vector alone) cells exhibited a strong apoptotic response to carboplatin, while A-MEC-LAP cells exhibited a weak apoptotic response. In an attempt to identify the mechanism of the inhibitory effect on apoptotic response to carboplatin, we next assessed the expression of cleaved caspases and PARP cleavage. While treatment of A-MEC-pc cells with carboplatin exhibited increased levels of cleaved caspase 3, caspase 7 and caspase 9 compared to that after no treatment, A-MEC-LAP cells did not show any expression of these caspases. These results suggest that P-LAP reduces sensitivity to anticancer drugs via inhibition of mitochondria-mediated apoptosis, and may be a molecular target for conquering anticancer drug resistance.
authors.affiliation: Department of Obstetrics and Gynecology, Nagoya University Graduate School of Medicine, Nagoya, Japan. shiba@med.nagoya-u.ac.jp
authors.forename: Chihiro
authors.initials: C
authors.lastname: Kondo
authors.forename: Kiyosumi
authors.initials: K
authors.lastname: Shibata
authors.forename: Mikio
authors.initials: M
authors.lastname: Terauchi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kajiyama
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Ino
authors.forename: Seiji
authors.initials: S
authors.lastname: Nomura
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nawa
authors.forename: Shigehiko
authors.initials: S
authors.lastname: Mizutani
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Kikkawa
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D016190:Carboplatin / Q000494:pharmacology*; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D010122:Cystinyl Aminopeptidase / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D019008:Drug Resistance, Neoplasm; D016889:Endometrial Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D006801:Humans; D017239:Paclitaxel / Q000494:pharmacology; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D014162:Transfection; D051020:bcl-X Protein / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D051020:bcl-X Protein; D016190:Carboplatin; D011065:Poly(ADP-ribose) Polymerases; D010122:Cystinyl Aminopeptidase; C105964:leucyl-cystinyl aminopeptidase; D020169:Caspases; D017239:Paclitaxel