Effects of an Inhibitor of the Gamma-Secretase Complex on Proliferation and Apoptotic Parameters in a FOXL2-Mutated Granulosa Tumor Cell Line (KGN)

IRUSTA G, PAZOS MC, ABRAMOVICH D, DE ZUÑIGA I, PARBORELL F, TESONE M.

BIOLOGY OF REPRODUCTION

SOC STUDY REPRODUCTION

Lugar: Madison; Año: 2013

0006-3363

Ovarian granulosa cell tumors (GCTs) represent 3-5% of all ovarian malignancies. Treatments have limited proven efficacy and biologically targeted treatment is lacking. The aim of this study was to investigate the role of Notch signaling in the proliferation, steroidogenesis, apoptosis, and PI3K/AKT pathway in a FOXL2-mutated granulosa tumor cell line (KGN), representative of the adult form of GCTs. When Notch signaling is initiated, the receptors expose a cleavage site in the extracellular domain to the metalloproteinase TACE and, following this cleavage, Notch undergoes another cleavage mediated by the presenilin-γ-secretase complex. To achieve our goal, DAPT, an inhibitor of the γ-secretase complex, was used to investigate the role of the Notch system in parameters associated with cell growth and death, using a human granulosa cell tumor line (KGN) as an experimental model. We observed that JAGGED1, DLL4, NOTCH1 and NOTCH4 were highly expressed in KGN cells as compared to granulosa-lutein cells obtained from ART patients. The proliferation and viability of KGN cells, as well as progesterone and estradiol production, decreased in the presence of 20 µM DAPT. Apoptotic parameters like PARP and caspase 8 cleavages, BAX and BCLXshort increased in KGN cells cultured with DAPT, while others such as BCL2, BCLXlong, FAS and FASL did not change. AKT phosphorylation decreased and PTEN protein increased when Notch signaling was inhibited in KGN cells. We conclude that the Notch system acts as a survival pathway in KGN cells, and might be interacting with the PI3K/AKT pathway.