QUANTITATION OF HUMAN CHORIOCARCINOMA SPHEROID ATTACHMENT TO UTERINE EPITHELIAL-CELL MONOLAYERS

Adhesive interactions of trophoblast cells with the endometrium are es sential for embryo implantation in the uterus. Choriocarcinoma cells, the malignant counterpart of trophoblast, show pronounced invasiveness and are of interest for model studies. We describe here an in vitro m odel system for the study of adhesion of human JAR choriocarcinoma mul ticellular spheroids to different human endometrial epithelial cell li nes (RL95-2, HEC-1A, KLE, AN3-CA) grown as monolayers. Cell characteri zation showed JAR spheroids to secrete the placental hormones human ch orionic gonadotropin and progesterone into the culture medium; distinc t patterns of keratin, vimentin, and uvomorulin expression were seen i n the endometrial cell lines. Spheroid attachment to endometrial monol ayers was quantified using a centrifugal force-based adhesion assay, a nd morphology was examined by light and electron microscopy. Results s howed the JAR spheroids to attach to three of the endometrial monolaye rs (RL95-2, HEC-1A, KLE) progressively over a 24-h period (by which ti me greater-than-or-equal-to 80% of the spheroids attached). Significan t differences in spheroid attachment were most pronounced at 5 h (RL95 -2 > HEC-1A > KLE and poly-D-lysine control, i.e. 90:45:17:17% attache d). JAR spheroids did not attach to the endometrial cell line AN3-CA. Morphology revealed choriocarcinoma cells to begin to intrude between the uterine RL95-2 epithelial cells at 5 h. At 24 h, this intrusive ty pe of penetration continued to be seen only with the RL95-2 monolayer. The assay system thus identifies differences in attachment properties between choriocarcinoma cells and various endometrial cell lines and forms the basis for further studies on the molecular interactions invo lved.