Interaction between choriocarcinoma cell line (JAr) and human cytotrophoblasts in vitro

The effect of serum from women with preeclampsia on JAR (trophoblast-like) cell line

OBJECTIVE

Pathologic placentation has been implicated in the pathogenesis of preeclamsia. We sought to assess the effect serum obtained from women with preeclampsia would have on JAR human choriocarcinoma cells regarding growth, invasiveness, and matrix metalloproteinase (MMP) secretion as compared to normotensive pregnant woman.

METHODS

Blood was collected from 11 healthy pregnant women and from10 patients with preeclampsia at 28-33 weeks of gestation. The JAR human choriocarcinoma cell line was cultured in the presence of 10% serum obtained from each group. Cell proliferation, invasiveness, and MMP secretion was measured using a cell proliferation kit, the Matrigel (BD Biosciences, Beit-Ha'Emek, Israel) invasion assay, and gel zymography, respectively.

RESULTS

Cell growth increased by 6% when exposed to serum from patients with preeclampsia compared to 30% from controls (P <.01). Trophoblast invasion was significantly (P <.01) reduced in the preeclampsia group (21 +/- 1.9%) compared to controls (27 +/- 2.5%). Valid MMP-2 secretion was reduced by 51% in the preeclampsia group compared to controls (P <.05).

CONCLUSION

Serum obtained from women with preeclampsia contains a factor or factors that exhibit an inhibitory effect on JAR trophoblast cell proliferation, invasiveness, and MMP-2 secretion. These factors may be involved in the pathologic placentation associated with the pathogenesis of preeclampsia.

Endocrine cell lines from the placenta

Cell-lines derived from human placenta and chorion have been used extensively to model the endocrine functions of human trophoblast. In general terms, the endocrine functions of the primary cells and tissues are at least partially replicated within the cell-lines, suggesting that they may be used as appropriate models. There are, however, two major provisos that compromise this generalisation. Firstly, the endocrine function of placenta represents a complex interaction between cytotrophoblast, syncytiotrophoblast and multiple regulators, so a single cell population digested from the normal environment is unlikely to represent this. Secondly, the characterisation of primary trophoblast populations and of cell-lines is incomplete, complicating the assignment of functions to trophoblast populations. Despite these difficulties, useful information has been obtained from the available cell-lines, regardless of whether they have arisen spontaneously, been transformed in vitro, or derived from cancers in vivo.

Expression and importance of matrix metalloproteinase 2 and 9 (MMP-2 and -9) in human trophoblast invasion

BACKGROUND

The aim of this study was to examine the invasiveness of first trimester trophoblasts according to the secretion profile of MMP-2 and -9 at different gestational stages, and to test the similarity between primary trophoblast cell-culture and the JAR choriocarcinoma cell-line.

METHODS

First trimester trophoblasts were divided into two groups: 6-8 weeks (early) and 9-12 w (late) of gestation. The two trophoblast groups and JAR cells were cultured in medium, with various concentrations of forskolin and Epidermal Growth Factor (EGF). Proteolytic activity was detected by zymography and invasiveness was assessed by Matrigel invasion assay. Student's T-test was used for statistical analysis.

RESULTS

In 6-8 w trophoblast, proMMP-2 was only slightly dominant over proMMP-9 (53.2% vs. 46.8% respectively), whereas in 9-12 w, proMMP-9 was clearly dominant over proMMP-2 (61.7% vs.38.3% respectively). In JAR cells proMMP-2 was strongly dominant (90.2% vs.9.8% respectively). In JAR cells forskolin significantly increased proMMP-2 and -9 secretion (128.5% +/- 12 and 183.2% +/- 27.9 of control, respectively). EGF had a dual effect on JAR cells: at 8 ng/ml both proMMP-2 and -9 were increased (133.5% +/-15 and 223.9% +/- 32.4 of control, respectively) while at 80 ng/ml both proMMP-2 and -9 were decreased (65.1% +/- 18.3 and 66.6% +/- 37 of control, respectively). Forskolin significantly increased both proMMP-2 and -9 secretion in 6-8 w and 9-12 w trophoblasts (125.9% +/- 6.3,128.4% +/- 6.4; 169.7% +/- 20.3, 120.3% +/- 4.5 of control, respectively). EGF also significantly increased both proMMP-2 and -9 secretion in 6-8 w and 9-12 w trophoblasts (141.22% +/- 14.8, 138.8% +/- 10.3; 168.3% +/- 18.2, 117.3 +/- 3.8 of control, respectively). Both forskolin and EGF increased trophoblast cells invasiveness in all groups. The invasive ability of trophoblast cells, induced by forskolin, was reduced by MMP-2 antibody in: JAR cells, 6-8 w and 9-12 w trophoblasts. Likewise trophoblast invasion induced by EGF was reduced by MMP-2 antibody in all groups. However the invasive ability induced by forskolin or EGF was inhibited by MMP-9 antibody only in trophoblasts from 9-12 w.

CONCLUSIONS

First trimester trophoblasts express differential gelatinase secretion profile according to the gestational week. In JAR and early trophoblasts (6-8 w) MMP-2 is the main gelatinase and the key enzyme in trophoblast invasion. Thereafter in late first trimester trophoblasts (9-12 w), both MMP-2 and -9 participate in trophoblast invasion.

Expression of urokinase, plasminogen activator inhibitors and urokinase receptor in pregnant rhesus monkey uterus during early placentation

We have investigated plasmin mediated proteolysis associated with trophoblast invasion during early stages of pregnancy in the rhesus monkey. In situ hybridization and immunocytochemical localization were used to define the cellular and tissue distribution of urokinase plasminogen activator (uPA), plasminogen activator inhibitor type 1 (PAI-1) and 2 (PAI-2) and urokinase receptor in early monkey placenta and uterus. Our results indicate: (1) uPA is expressed in proliferating and invasive cytotrophoblast located in chorionic villi as well as in extravillous trophoblast associated with uterine arterioles. This raises the possibility that urokinase may play an important role in trophoblast invasion. (2) PAI-1 mRNA is specifically localized in two areas where invasive trophoblast cells encounter maternal tissue directly. The extravillous cytotrophoblast cells at the maternofetal junction express PAI-1 mRNA. The invasive endovascular trophoblast cells within the uterine arterioles also express PAI-1 mRNA. The location sensitive expression of PAI-1 mRNA at the maternofetal junction may imply a protective function of this protease inhibitor that might be induced through interaction with decidual cells. (3) Urokinase receptor antigen has also been found at the maternofetal junction and in endovascular trophoblast cells of the invaded maternal blood vessel. (4) PAI-2 immunoreactivity is found in association with cytotrophoblast cells in anchoring choronic villi suggesting its association with early placentation. In conclusion, we propose that the plasmin/plasminogen activator system may not only regulate extracellular matrix degradation, but also modify migration and invasive behaviour of extravillous trophoblast cells, during early placentation.