Fas Antigen-Mediated Apoptosis of Ovarian Surface Epithelial Cells*

Abstract

The Fas antigen is a cell surface receptor that, when engaged by Fas ligand or specific agonistic antibodies, triggers apoptosis. The effect of an agonistic monoclonal antibody to mouse Fas antigen (Fas mAb, clone J02) on the viability of cells from dispersed mouse corpora lutea (CL cultures) was tested. Cultures were prepared by enzymatic digestion of CL from day 4 -7 pseudopregnant mice. Cultures were pretreated with 0, 1, 10, 100, or 1000 U/ml murine interferon-␥ (IFN) at 72 h of culture. IFN has been shown to increase Fas antigen expression in a number of cell types. At 96 h (time zero), cultures were treated with Fas mAb or IgG. By 4 h after Fas mAb treatment, discrete homogeneous patches of cells within the cultures showed characteristic signs of apoptosis, including blebbing of cell membranes, detachment, and disappearance from the culture. CL cultures contain luteal, stromal, and endothelial cells; fibroblasts; and surface epithelial cells (OSE). Cells dying in response to Fas mAb were identified as OSE. Affected cells had the cobblestone appearance and distinct nuclei typical of epithelial cells. Unlike luteal cells, OSE did not stain with the lipophilic dye, Nile red. The cells did not stain with acetylated low density lipoprotein conjugated to the fluorescent marker octadecyl indocarbocyanine, a marker for endothelial cells and monocytes. Cells in patches stained positively for cytokeratin, a marker for epithelial cells. Fas-mediated cytotoxicity was quantified by counting the number of cells present in discrete patches of OSE 0 and 8 h after Fas mAb treatment. Fas mAb treatment had no effect in cultures pretreated with 0 or 1 U/ml IFN, but induced significant death of OSE in cultures pretreated with 10, 100, and 1000 U/ml IFN (37 Ϯ 11%, 54 Ϯ 18%, and 60 Ϯ 11%, respectively). There was no apparent effect of Fas mAb on other cell types within the CL cultures. To confirm that cells dying in response to Fas mAb were OSE, experiments were also performed on enriched cultures of OSE prepared by enzymatic digestion of the outer surface of the ovary. In enriched OSE cultures pretreated with 200 U/ml IFN, there was 44% killing in response to Fas mAb, whereas in cells not pretreated with IFN, there was no effect. T HE OVARY is covered with a single layer of epithelial cells, the ovarian surface epithelial cells (OSE). OSE on the preovulatory follicle undergo apoptosis at the time of ovulation (1, 2) and then proliferate rapidly to repair the ruptured follicle and cover the surface of the developing corpus luteum (CL) (3). OSE are important in the oncogenesis of ovarian cancer; more than 90% of ovarian cancers arise from the OSE (4). It has been postulated that the oncogenic potential of OSE is linked to the extensive proliferation of these cells that is required during each ovulatory cycle (5). Factors affecting the death and proliferation of OSE are poorly understood. Defining these factors could provide insight into the processes by which OSE are transformed into cancerous cells.The Fas antigen (CD95,...

Expression and Function of PAIRBP1 Within Gonadotropin-Primed Immature Rat Ovaries: PAIRBP1 Regulation of Granulosa and Luteal Cell Viability1

“…Like thecal/interstitial cells, ovarian surface epithelial cells do not frequently apoptose. Rather, only those surface epithelial cells associated with the site of follicular rupture at the time of ovulation have been shown to undergo apoptosis at any appreciable rate [26,32]. It is possible that the high levels of PAIRBP1 within these cells could be involved in maintaining their viability because PAIRBP1 mediates P4's antiapoptotic action in granulosa and luteal cells (see subsequent discussion).…”

“…The only modification was that the cells were stained with YOPRO-1 and Nile Red (5 g/ ml) [25][26][27]. Nile Red stained the lipid droplets, allowing for the identification of well-differentiated luteal cells [25,26].…”

Significance of Fas receptor protein expression in epithelial ovarian cancer

“…It has been postulated that the first step in tumorigenesis is the formation of epithelial ICs derived from such crypts or by invagination of the surface epithelium [42]. It has been shown that the cells lining these cysts express FasR and are normally removed by apoptosis, and any derangement during this process would allow for persistence of the ICs with increasing risk of developing ovarian cancer [20,43].…”

Expression and Activity of the Fas Antigen in Bovine Ovarian Follicle Cells1

“…Fas antigen mRNA was quantified by a competitive RT-PCR assay described previously for measurement of mouse Fas antigen mRNA [11] and modified for use with bovinespecific primers and controls. RNA was reverse transcribed in the presence of various concentrations of an internal standard RNA.…”

“…Cultured ovarian cells from the human and mouse were resistant to killing by cytotoxic Fas mAb unless the cells were pretreated with the cytokines, interferon (IFN) or IFNϩTNF, or with cycloheximide [3,10,11]. Studies of Fas expression and function in the ovary have been limited pri- 1 This work was supported by grants from the USDA (98-35203-6220) and NIH (HD 32535).…”