The Expression and Localization of Neutral Endopeptidase 24.11/CD10 in Human Gestational Trophoblastic Diseases

Abstract

SUMMARY:Neutral endopeptidase 24.11 (NEP)/CD10 is a cell-surface peptidase that hydrolyzes various bioactive peptides.NEP is distributed in both normal and neoplastic cells and plays a functional role by modulating cellular responses to peptide substrates. Recently, NEP has been shown to be expressed in normal placental trophoblasts, suggesting its physiological role during pregnancy. In the present study, we investigated the expression of NEP in hyperplastic and anaplastic trophoblasts in gestational trophoblastic diseases (GTDs). Flow cytometric analysis demonstrated that NEP was expressed in all choriocarcinoma cell lines examined. The NEP enzyme activity in these cell lines correlated with cell-surface protein levels and was abolished by the NEP inhibitor phosphoramidon. On immunoblot analysis, NEP protein was detected in both hydatidiform mole and choriocarcinoma tissues as a double band of 95 and 100 kDa similar to that of the normal placental tissues. Immunohistochemical analysis revealed that NEP was present on syncytiotrophoblasts, while no or very faint NEP immunoreactivity was observed on cytotrophoblasts in the normal placenta. Similarly, NEP in hydatidiform mole and invasive mole was localized on the membrane of syncytiotrophoblasts, but not on hyperplastic cytotrophoblasts. In contrast, in choriocarcinoma, NEP was highly expressed not only on syncytiotrophoblastic cells but also on invading anaplastic cytotrophoblasts. In addition, NEP was also expressed on intermediate trophoblasts in placental site trophoblastic tumors. In summary, this is the first study demonstrating the expression of NEP/CD10 in GTDs. The differential localization of NEP among various trophoblastic tumors suggests that NEP may play a functional role in the regulation of trophoblast transformation and human chorionic gonadotropin secretion. (Lab Invest 2000, 80: 1729 -1738.

Gestational Trophoblastic Tumors and Related Tumor-Like Lesions

“…Although leukemia inhibitory factor plays an important role in implantation and placentation in several species, the paracrine role of leukemia inhibitory factor in the biology of human implantation site intermediate trophoblastic cells is not known. Those intermediate trophoblastic cells also express CD10, a neutral endopeptidase [64,122].…”

Expression of Placental Leucine Aminopeptidase and Adipocyte-Derived Leucine Aminopeptidase in Human Normal and Malignant Invasive Trophoblastic Cells

“…Contrary to P-LAP or A-LAP, DPPIV, the aminopeptidase cleaving certain chemokines, was selectively expressed in the noninvasive phenotype EVTs, and down-regulation of DPPIV was associated with EVT invasion . Our previous studies also showed that neutral endopeptidase (NEP), another peptidase degrading endothelin-1 that is one of the peptides promoting EVT invasion (Chakraborty et al, 2003), was expressed in differentiated syncytiotrophoblasts but not in invasive EVTs (Ino et al, 2000;Uehara et al, 2001). Thus, whether these peptidases function as a positive or negative regulator of the invasiveness of EVT appears to be dependent on the type of target peptide sub- …”

“…Immunohistochemical staining was performed using the avidin-biotin immunoperoxidase technique as described previously (Ino et al, 2000). Sections were cut at a thickness of 4 m. For heat-induced epitope retrieval, deparaffinized sections in 0.01 M citrate buffer were treated three times for 5 minutes at 95°C in a microwave oven.…”