Establishment and characterization of an ovarian yolk sac tumor cell line reveals possible involvement of Nkx2.5 in tumor development

Objective: Ovarian yolk sac tumor (YST) is rare and highly malignant. Up to the present, there have been no cell lines of human ovarian YST constructed and, therefore, no studies on their cell function. The purpose of this study was to establish a human ovarian YST cell line to be able to identify a target for novel molecular-based therapy. Methods: A 28-year-old woman underwent right salpingo-oophorectomy for right ovarian YST. YST cell lines (NOY1 and NOY2) were established from surgical specimens, and NOY1 cells were characterized. We also transfected them with small interfering RNA (siRNA) oligonucleotides specific for human Nkx2.5 and investigated cell proliferation compared to control siRNA-transfected cells. Results: The cell lines were successfully maintained both in culture and in nude mice. Histological examination showed that xenografted tumors were composed of cells in solid and glandular patterns of YST. These cells were positively immunostained for AFP. Nkx2.5 siRNA-transfected NOY1 cell viability decreased by 50% compared to that of control-siRNA- transfected cells. Conclusions: This is the first report of a cell line established from human YST. Analysis of this new cell line suggested that Nkx2.5 can be a new molecular target in the treatment of ovarian YST.