CONICET | Buscador de Institutos y Recursos Humanos

Gestational Trophoblastic Disease (GTD) comprises a group of entities including hydatiform mole (HM) (classified as complete or partial depending on maternal genetic contribution and expression of p57kip2 protein), and tumors like choriocarcinoma (CC), placental-site trophoblastic tumor (PSTT) and epithelioid trophoblastic tumor (ETT). They represent malignant fetal allografts in maternal tissues (1). Although tumors may frequently develop after a molar pregnancy, they can also arise after a term or ectopic pregnancy and even after abortion. Hyaluronan (HA) plays an important role in physiological processes and in malignant events as part of tumor microenvironment or being expressed by malignant cells, contributing to tumor survival and progression (2). HA is able to modulate cell-signaling pathways upon interaction with receptors like CD44 or the receptor for hyaluronan-mediated motility (RHAMM), among others. While CD44 is a cell surface receptor, RHAMM behaves as an itinerant protein. It can be found within the cytoplasm and even in the nucleus of the cell (3). Several studies demonstrated the expression of such proteins in tumors and its association with prognosis. The aim of this work was to study the expression and distribution of HA, CD44 and RHAMM in GTD tissues and different human choriocarcinoma cell lines to analyze the functional role of such molecules. First we classified HM in complete or not by p57kip2, then we analyzed the presence and distribution of HA, CD44 and RHAMM in patients biopsies by immunohistochemistry. Tissues from 4 early placentas, 9 MH, 2 CC and 1 PSTT were collected from the Pathology Service of Hospital Carlos Durand, Buenos Aires, Argentina. We also investigated the expression of such molecules in three human choriocarcinoma cell lines: JAR, JEG-3 and BeWo. Protein expression was analyzed by Western Blot and Immunofluorescence while HA secretion by ELISA-like assay. Besides, we studied the effect of different molecular weight HA on cell proliferation by tritiated-timidine incorporation. Our results showed different pattern expression of RHAMM and AH in GTD tissues. In complete HM, RHAMM immunoreactivity was found in cytoplasm of villous cytotrophoblast, it was stronger than the signal detected from early placentas, and in apical membrane of villi. Instead, HA immunoreactivity was found in villous stroma, in a different pattern respect to early placentas, as well as in the apical and basal membrane of villi. In choriocarcinoma, RHAMM staining was found in the tumor cell membrane while HA and CD44 were related to the tumor stroma. In PSTT, RHAMM staining was found in the nucleus while HA and CD44 were not expressed. On human choriocarcinoma cell lines, analysis of HA receptors showed that none of them expressed CD44 while RHAMM was found in JEG-3 cell line, located within the cytoplasm and also on cell surface. Only BeWo cell line showed a higher basal secretion of HA respect to its cell-free medium. HA was unable to induce cell proliferation on choriocarcinoma cells in accordance with the absence of HA staining on tumor cells. Our results suggest that RHAMM may be involved in the pathophisiology of GTD although further studies will be necessary to elucidate which form of RHAMM might be a useful marker to GTD tissues. Furthermore, we propose that JEG-3 cell line may be an appropriate model to study the involvement of HA-RHAMM interaction. Studies are been carrying out to evaluate the role of this event on migration and invasion processes. 1. Shih I-M. 2007. The Lancet Oncology 8: 642-50 2. Sironen RK, Tammi M, Tammi R, Auvinen PK, Anttila M, Kosma VM. 2011. Experimental Cell Research 317: 383-91 3. Maxwell CA, McCarthy J, Turley E. 2008. Journal of Cell Science 121: 925-32