Placental leucine aminopeptidase (P-LAP) and glucose transporter 4 (GLUT4) expression in benign, borderline, and malignant ovarian epithelia.

OBJECTIVE: Increased glucose consumption is a characteristic of malignant cells. Glucose is transported into the cell via facilitative glucose transporters, which are known to be members of a supergene family. The insulin-responsive GLUT4 isoform is expressed almost exclusively in insulin target tissues. P-LAP is a cell surface aminopeptidase, and is a synonym for oxytocinase. P-LAP is also referred to as insulin-regulated membrane aminopeptidase (IRAP) associated with GLUT4-containing vesicle. The authors evaluated P-LAP and GLUT4 expression in benign, borderline, and malignant ovarian epithelia. METHODS: Histologic sections of formalin-fixed, paraffin-embedded specimens from 11 patients with benign serous or mucinous cystadenomas, 14 patients with serous or mucinous borderline tumors, and 80 patients with epithelial-ovarian adenocarcinomas (29 serous, 17 endometrioid, 14 mucinous, and 20 clear cell adenocarcinomas) were stained for P-LAP and GLUT4 using each polyclonal antibody. Expressions of P-LAP and GLUT-4 in ovarian cancer cells were detected by Western blotting. RESULTS: P-LAP immunoreactivity was detected in 2 of 11 benign cystadenomas. None of the 11 benign ovarian tumors showed any immunoreactivity for GLUT4. Seven of 14 borderline tumors demonstrated P-LAP immunoreactivity, while 5 of 14 borderline tumors demonstrated GLUT4 immunoreactivity. P-LAP was expressed in 23 of 29 in serous, 15 of 17 endometrioid, 13 of 14 mucinous, and all clear-cell adenocarcinomas. The tendency toward increased P-LAP expression with advancing grade was observed in serous adenocarcinomas. GLUT4 was expressed in 13 of 29 serous, 13 of 17 endometrioid, 13 of 14 mucinous, and 18 of 20 clear-cell adenocarcinomas. In invasive carcinomas, there was a direct correlation between P-LAP immunoreactivity and GLUT4 immunoreactivity (correlation coefficient [r] = 0.58; P < 0.01). Furthermore, P-LAP overexpression in SKOV3 cells induced the GLUT4 expression. CONCLUSIONS: P-LAP and GLUT4 are available not only for the evaluation of ovarian epithelial malignancy, but also as targets for molecular therapy. Further study to investigate the roles of P-LAP and GLUT4 in ovarian carcinoma is needed.

Possible involvement of adipocyte-derived leucine aminopeptidase via angiotensin II in endometrial carcinoma.

OBJECTIVE: It has recently been appreciated that a local autocrine or paracrine renin-angiotensin system (RAS) may exist in a number of tissues. Angiotensin II (AngII) is a potent RAS-derived vasoconstrictor peptide, and it is involved in tumor angiogenesis. We have cloned human adipocyte-derived leucine aminopeptidase (A-LAP), which degrades Ang II. This study investigated whether the expression of A-LAP, Ang II, angiotensin type I receptor (AT1R) and vascular endothelial growth factor (VEGF) correlates with clinicopathologic factors and prognosis in patients with endometrial endometrioid adenocarcinoma. METHODS: Histologic sections of formalin-fixed, paraffin-embedded specimens from 94 primary endometrial carcinomas were stained for A-LAP, AngII, AT1R and VEGF using each antibody. Disease-free survival (DFS) and other clinicopathologic characteristics were analyzed according to the intensity of each staining. RESULTS: Of 94 cases, 91 (96.8%) showed specific A-LAP immunostaining. A-LAP expression demonstrated negative correlations with myometrial invasion (p = 0.01) and vascular infiltration (p = 0.01). Of 94 cases, 77 (81.9%) showed specific AngII immunostaining. We found a positive correlation between AngII expression and surgical stage (p = 0.01). Of 94 cases, 56 (59.6%) showed specific AT1R immunostaining and 73 (77.7%) specific VEGF immunostaining. We found a positive correlation between VEGF expression and lymph node metastasis (p = 0.05). AngII and AT1R expression predicted a significantly poorer prognosis. Contrarily, A-LAP expression indicated a significantly more favorable prognosis in endometrial endometrioid adenocarcinoma patients. Multivariate analysis demonstrated that A-LAP expression (odds ratio, 0.12; 95% confidence interval, 0.025-0.618; p = 0.01) was an independent prognostic factor. CONCLUSIONS: In this study, we demonstrated the existence of local RAS and A-LAP in endometrial endometrioid adenocarcinoma as prognostic predictors of clinical outcome. These findings suggest that the assessment of RAS and A-LAP status provides clinically useful prognostic information in patients with endometrial carcinoma.

Placental leucine aminopeptidase (P-LAP) expression is associated with chemosensitivity in human endometrial carcinoma.

OBJECTIVE: Although treatment for advanced or recurrent endometrial carcinoma has improved over recent years with the introduction of paclitaxel- and platinum-based chemotherapy, in most, the disease remains incurable because of resistance to chemotherapy. In the previous study, we have shown that placental leucine aminopeptidase (P-LAP) is associated with poor prognosis. The objective of this study was to determine whether P-LAP expression affects the chemosensitivity in endometrial carcinoma patients. METHODS: Here, we investigated the effect of P-LAP to response for paclitaxel and carboplatin in advanced and recurrence endometrial carcinoma. Furthermore, we transfected P-LAP cDNA into endometrial carcinoma cells (AMEC) and investigated cell growth and apoptosis by paclitaxel or carboplatin. RESULTS: In 15 of 17 patients, P-LAP was positive. Twelve of seventeen patients were evaluable for response. Among the eight patients strongly positive for P-LAP, only two patients (25%) showed PR. However, all four patients who were weakly positive for P-LAP showed either complete response (CR) or partial response (PR). P-LAP overexpressor (P-LAP2 and P-LAP8) and a vector control were used to assay chemosensitivity. P-LAP2 clone displayed a 1.7-fold increase in IC(50) against paclitaxel and carboplatin when compared with the vector control, and P-LAP8 clone displayed a 1.6-fold increased in IC(50) against paclitaxel and carboplatin when compared with V1. Compared to vector control cells, apoptotic effect by carboplatin treatment was clearly inhibited in P-LAP2 and P-LAP8 cells. Carboplatin, 10(-6) M, induced the 12.5-fold rate of apoptosis compared to that without treatment at 48 h in vector control cells. However, in P-LAP2 and P-LAP8 clones, 10(-6) M carboplatin induced only 3.2- and 5.1-fold rates of apoptosis, respectively, compared to that of without treatment. CONCLUSIONS: P-LAP was suggested to be involved in reducing chemosensitivity and may be a therapeutic target in endometrial carcinoma.

Expression of placental leucine aminopeptidase is associated with a poor outcome in endometrial endometrioid adenocarcinoma.

OBJECTIVE: Placental leucine aminopeptidase (P-LAP) is a cell surface aminopeptidase (oxytocinase). We cloned P-LAP cDNA and found a widespread tissue distribution of P-LAP. Since P-LAP can degrade several small peptide hormones such as oxytocin, this enzyme may affect many cellular functions of carcinoma cells as well as normal cells. This study investigated whether the expression of P-LAP correlates with clinicopathologic factors and prognosis in patients with endometrial endometrioid adenocarcinoma. METHODS: Histologic sections of formalin-fixed, paraffin-embedded specimens from 99 primary endometrial carcinomas were stained for P-LAP using polyclonal P-LAP antibody. Disease-free survival and other clinicopathologic characteristics were analyzed according to the intensity of P-LAP staining. RESULTS: Of 99 cases, 69 (69.7%) showed specific P-LAP immunostaining. We found a positive correlation between the expression of P-LAP and histological grade (p < 0.01), surgical stage of the disease (p = 0.02), myometrial invasion (p = 0.01), lymph node involvement (p < 0.01), and vascular infiltration (p < 0.01). In patients who had strongly positive P-LAP staining, the disease-free interval was significantly lower than in patients who had negative or weakly positive P-LAP staining (p < 0.01). Multivariate analysis demonstrated that strongly immunoreactive P-LAP (odds ratio, 12.8; 95% confidence interval, 2.84-58.8; p < 0.01) and surgical stage (odds ratio, 8.78; 95% confidence interval, 2.77-27.8; p < 0.01) are independent prognostic factors. CONCLUSIONS: This study suggests P-LAP as an independent prognosticator of clinical outcome in patients with endometrial carcinoma. Therefore, assessment of the P-LAP status provides clinically useful prognostic information in patients with endometrial carcinoma.

Stromal cell-derived factor-1alpha-induced cell proliferation and its possible regulation by CD26/dipeptidyl peptidase IV in endometrial adenocarcinoma.

CD26/dipeptidylpeptidase IV (DPPIV) is a 110 kD membrane-bound extracellular peptidase with ubiquitous expressions, and has a variety of functional properties in the development of human malignancies as well as T-cell biology. According to recent reports, stromal cell derived factor-1alpha (SDF-1alpha), which is a good substrate for CD26/DPPIV, is expressed in various solid tumors and is involved in tumor development or metastasis. We investigated the expression of SDF-1alpha and its corresponding receptor, CXCR4, in human endometrial carcinoma (EMCA) tissues and the function of SDF-1alpha on EMCA cells with its regulation by CD26/DPPIV. We demonstrated that SDF-1alpha and CXCR4 were expressed in human EMCA, and these immunoreactivities were significantly low in Grade 3 EMCA, which was similar to that of CD26/DPPIV, compared to those in Grade 1 and Grade 2. Additionally, exogenous SDF-1alpha concentration was significantly lower in CD26/DPPIV-transfected EMCA cells than that in vector-transfected cells. Moreover, exogenous SDF-1alpha significantly stimulated cell proliferation in vector-transfected cells in a concentration dependent manner. In contrast, in CD26/DPPIV-transfected cells, there was no apparent effect on proliferation shown by the addition of exogenous SDF-1alpha. This is the first report showing a direct link between the SDF-1alpha/CXCR4 pathway with CD26/DPPIV in solid tumors, suggesting that CD26/DPPIV is likely to directly modulate various SDF-1alpha induced functions.