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Wael Traboulsi

Role of EG-VEGF (Endocrine Gland-Derived Vascular Endothelial Growth Factor) in the development and progression of placental tumors: The case of choriocarcinoma

Published on 12 December 2016


Thesis presented on December 12, 2016

Abstract:
Choriocarcinoma is a highly malignant trophoblastic tumor that often develop from molar pregnancies also called hydatidiform mole (HM). Nevertheless, HM progression towards choriocarcinoma remains uncharacterized. Involvement of angiogenic factors in this process is proposed. Here, we investigated the role of a new placental angiogenic factor, EG-VEGF (Endocrine Gland-Derived Endothelial Growth Factor) in choricarcinoma pathogenesis. EG-VEGF acts via two GPCR receptors PROKR-1 and PROKR-2. Three approaches were used to verify this hypothesis. A clinical approach using sera and placental samples collected from HM (n=38) Choriocarcinoma patients (n=3) and from normal pregnant women (n=18); all collected during the first trimester of pregnancy. An in vitro approach using JEG3 cells, a human choriocarcinoma cell line and normal first trimester trophoblast cells (NTC). An in vivo approach that aimed at developing an animal model of choriocarcinoma in which therapeutic agents have been tested. Circulating EG-VEGF levels were significantly higher in HM and choriocarcinoma compared to normal patients. Placental EG-VEGF, PROKR1 and PROKR2 expression exhibited the same pattern. In JEG3 cells, EG-VEGF increased i) the expression of PROKR-1 and PROKR-2, ii). Their migration, proliferation invasion and spheroid formation using both 2 and 3D culture systems. These effects were abolished using PROKR1 and PROKR2 antagonists, iii) phosphorylation of different proteins implicated in tumor progression as well as secretion of MMP-2 and MMP-9. Choriocarcinoma model has been developed by injection of JEG3 cells orthotopically within the placenta of SCID mice. Within 12 days, injected gravid mice developed a choricarcinoma that metastasis in multiple organs. Importantly, injection of EG-VEGF receptors antagonists significantly reduced tumor development and its progression. Also, we have characterized the mechanism by which EG-VEGF contributes to tumor progression. This mechanism involves the cleavage of the key junctional protein, the VE-cadherin, following its phosphorylation at the tyrosine 685, by EG-VEGF. In total my thesis project i) demonstrated the direct involvement of the EG-VEGF in the development and progression of choriocarcinoma ii) elucidated the mechanism of this progression and iii) proposes a potential therapeutic for choriocarcinoma through the antagonisation of its receptors.


Keywords:
Placenta, Hydatidiform mole, Choriocarcinoma, EG-VEGF, Prokineticin receptors, Animal model, VE-Cadherin; Target therapy.

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