Luteinizing hormone inhibits Fas-induced apoptosis in ovarian surface epithelial cell lines.

Gonadotrophins including LH have been suggested to play an important role in the etiology of epithelial ovarian cancers. The goal of the present study was to obtain more insight in the mechanism of gonadotrophin action on ovarian surface epithelium (OSE) cells. As the Fas system is known to be a major player in the regulation of the process of apoptosis in the ovary, we investigated whether LH interfered with Fas-induced apoptosis in the human OSE cancer cell lines HEY and Caov-3.

Irregularly shaped inclusion cysts display increased expression of Ki67, Fas, Fas ligand, and procaspase-3 but relatively little active caspase-3.

Human ovarian cancers are thought to arise from sequestered ovarian surface epithelial (OSE) cells that line the wall of inclusion cysts. Nevertheless, the early events toward neoplasia are not well understood. In this study, immunoreactivity for apoptotic proteins in human OSE of control and tumor ovarian sections was examined.

Etiology of ovarian cancer: a proposed mechanism.

The majority of ovarian cancers are derived from ovarian surface epithelial cells that are sequestered in inclusion cysts within the ovarian stroma. We propose that the Fas/Fas ligand system is responsible for the normal elimination of these inclusion cysts through apoptosis, thereby removing potential sites of ovarian tumors. Furthermore, we hypothesize that the failure of the Fas/Fas ligand's apoptotic signaling mechanism leads to the persistence of these inclusion cysts in the stroma, and the onset of ovarian tumorigenesis.

Identification of markers for precursor and leydig cell differentiation in the adult rat testis following ethane dimethyl sulphonate administration.

Administration of ethane dimethane sulphonate (EDS) to adult rats results in the destruction of all Leydig cells, followed by a complete regeneration. We investigated this regeneration process in more detail, using different markers for precursor and developing Leydig cells: the LH receptor, 3beta-hydroxysteroid dehydrogenase (3beta-HSD), transforming growth factor alpha (TGFalpha), and a new marker for Leydig cell maturation, relaxin-like factor (RLF). LH receptor immunoreactivity was found in Leydig cell-depleted testes at 3 and 8 days after EDS administration.

Transforming growth factor-beta inhibits DNA synthesis in immature rat Leydig cells in vitro.

TGFbeta isoforms and its receptors are present in the testis and regulate in vitro function of various testicular cells. We have investigated the effects of TGFbeta on basal and mitogen stimulated in vitro proliferation of immature rat Leydig cells. Leydig cells were cultured with TGFbeta1, either alone or in combination with hCG, steroidogenesis-inducing protein (SIP), interleukin-1beta (IL-1beta), insulin or TGFalpha, and the incorporation of [3H]thymidine into DNA was determined.

Activation of Fas ligand/receptor system kills ovarian cancer cell lines by an apoptotic mechanism.

The majority of ovarian cancers originate from the surface epithelium of the ovary and from inclusion cysts derived from the epithelium that becomes sequestered in the stroma. To identify naturally occurring ligands that could activate mechanisms by which these ovarian neoplasms could be eliminated, we have examined the ability of anti-Fas mAb to induce apoptosis in two cell lines, HEY and Caov-3, derived from ovarian carcinomas of surface epithelial origin. Treatment of each cell line with anti-Fas mAb caused chromatin condensation, nuclear segmentation, and apoptotic body formation, indicative of apoptosis.

Induction of apoptosis in thecal/interstitial cells: action of transforming growth factor (TGF) alpha plus TGF beta on bcl-2 and interleukin-1 beta-converting enzyme.

Follicular atresia is characterized by the initial rapid loss of granulosa cells by apoptosis, followed by the loss of thecal cells at a slower rate. We have previously shown that treatment of subconfluent cultures of thecal/interstitial cells (T/I) with transforming growth factor (TGF) alpha plus TGF beta caused chromatin condensation and internucleosomal fragmentation characteristic of apoptosis, whereas in the presence of either TGF alpha or TGF beta alone the cells remained healthy. In this study we have examined the effect of TGF alpha and TGF beta alone and in combination on the levels of mRNA encoding bcl-2 and interleukin-1 beta-converting enzyme (ICE) in T/I cells using a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay.

Fas-induced apoptosis in rat thecal/interstitial cells signals through sphingomyelin-ceramide pathway.

Of the ovarian follicles that develop during reproductive life, more than 99% do not ovulate and are eliminated from the ovary by follicular atresia. Atresia is achieved by the self destruction of thecal and granulosa cells that comprise the follicle, by the process of apoptosis. The objective of this study was to determine if activation of the Fas receptor could enact apoptosis of thecal cells, and to explore the signal transduction pathway involved.

Steroidogenesis-inducing protein, isolated from human ovarian follicular fluid, is a potent mitogen for cell lines derived from ovarian surface epithelial carcinomas.

The majority of human ovarian cancers originate from the surface epithelial (OSE) cells that surround the ovary. The incidence of OSE cancer is correlated with the number of ovulations that occur during fertile life. OSE cells remain quiescent but undergo rapid mitotic activity after ovulation to repair the wound.

Induction of apoptosis in rat thecal/interstitial cells by transforming growth factor alpha plus transforming growth factor beta in vitro.

In each estrous cycle dominant follicles are selected from a growing pool to develop to the preovulatory stage and to ovulate. Those follicles that do not ovulate must be eliminated in order to maintain the constant mass and homeostasis of the ovary. Granulosa cells are lost by apoptosis at the onset of follicular atresia, whereas apoptotic thecal cells are identified at later stages of atresia.

Dynamics of follicular growth and atresia of large follicles during the ovarian cycle of the guinea pig: fate of the degenerating follicles, a quantitative study.

Background: A quantitative integrated study of healthy ovarian follicles of different sizes and their mitotic activity and of clearly defined atretic stages of involuting large growing follicles at different stages of the guinea pig ovarian cycle is not available in the literature. We considered that such a study would reveal new aspects of ovarian tissue dynamics and provide new information in an organ with a continuous phenotypic transformation of its cellular components.

Methods: Ovaries from guinea pigs were removed on days 1 (opening of the vagina), 3, 6, 9, 13, and 16 of the cycle, and the following were measured in serial sections: (1) total number of healthy follicles falling into categories based on the volume occupied by granulosa cells, (2) total number of atretic follicles falling into clearly defined morphological stages of the degenerative and involutionary process affecting medium to large follicles, and (3) proportion of metaphase-arrested granulosa cells, after colcemid injection, in healthy follicles of different size categories.

Regulation of transforming growth factor alpha gene expression in an ovarian surface epithelial cell line derived from a human carcinoma.

The surface epithelium plays an important role in normal ovarian physiology: the cells proliferate in the vicinity of the developing preovulatory follicle to accommodate the increase in follicular size, and to repair the surface after ovulation. These bouts of mitotic activity in vivo must be strictly regulated by the activity of growth factors and their receptors. Since transforming growth factor alpha (TGF alpha) has been identified as a growth-promoting factor for normal surface epithelial cells from human ovaries and ovarian surface epithelial cell lines, we have examined the regulation of the TGF alpha gene in HEY cells, a surface epithelial cell line derived from a human ovarian carcinoma.

Immunolocalization of transforming growth factor alpha and luteinizing hormone receptor in healthy and atretic follicles of the adult rat ovary.

At the onset of the LH surge in the rat, the proliferation of granulosa cells in preovulatory follicles is inhibited, aromatase activity is attenuated, and the cells enter a further phase of differentiation to form the CL. Whereas the LH surge induces these changes in the granulosa cells, it is possible that the actions of LH are mediated or modulated by paracrine and/or autocrine factors. A factor that may modulate the actions of LH is transforming growth factor alpha (TGF alpha).

Transforming growth factor alpha localization and role in surface epithelium of normal human ovaries and in ovarian carcinoma cells.

Transforming growth factor alpha (TGF alpha) has been localized by immunohistochemistry in the ovarian surface epithelial (OSE) cells of sections from normal human ovaries and in epithelial cells of surface crypts. An ovarian cancer cell line (HEY) derived from the surface epithelium of a human ovary also exhibited intense staining for the TGF alpha peptide. Using Northern analysis, HEY cells were shown to express a 4.

Immunohistochemical localization of 3 beta-hydroxysteroid dehydrogenase in the rat ovary during follicular development and atresia.

In the adult ovary, cohorts of growing follicles are continuously generated, from which dominant follicles are selected during each estrous cycle. To compensate for the rapid proliferation of follicular cells in the growing pool of follicles, follicles are eliminated by atresia, thereby maintaining ovarian tissue mass. Estrogens and androgens have been implicated as intraovarian regulators of follicular growth and atresia, suggesting that the fate of an individual follicle to develop to the preovulatory stage or to undergo atresia is associated with distinct profiles of steroid production.

Interactions between FSH, estradiol-17 beta and transforming growth factor-beta regulate growth and differentiation in the rat gonad.

Estradiol-17 beta (E2) is a mitogen in vivo for the proliferation of granulosa cells in the rat ovary. E2 is synthesized by the preovulatory follicle through a series of gonadotrophin-dependent events: LH stimulates thecal cells to synthesize androgens (androstenedione and testosterone) which are substrates for FSH-induced aromatization to estrogens in granulosa cells. More recently, we have found that transforming growth factor-beta (TGF-beta) stimulates DNA synthesis in rat granulosa cells in vitro and this effect is augmented by FSH.

Steroidogenesis-inducing protein stimulates protein-tyrosine kinase activity in rat Leydig cells.

Steroidogenesis-inducing protein (SIP) isolated from human ovarian follicular fluid stimulates steroid production in Leydig cells, human luteal cells, and rat adrenal cells. In addition, SIP is a potent mitogen that stimulates the proliferation of Leydig cells from immature rats to a greater extent than do LH/hCG and other known growth factors. We have shown previously that the actions of SIP on Leydig cells are independent of the adenyl cyclase-cAMP pathway.

Localization of transforming growth factor beta 1 and beta 2 during testicular development in the rat.

The transforming growth factor beta s (TGF beta s) affect the metabolic activities of the somatic cells of the testis. Sertoli cells, peritubular/myoid cells, and germ cells contain mRNA for TGF beta 1 and/or TGF beta 2. We have used immunohistochemical techniques to determine, in vivo, when TGF beta 1 and TGF beta 2 are present in the rat testis during development and have identified the precise localization of these growth factors.

Transforming growth factor-alpha: identification in bovine corpus luteum by immunohistochemistry and northern blot analysis.

Transforming growth factor-alpha (TGF-alpha), a product of the thecal cells, has potent mitogenic and steroidogenic influences on cells within the ovarian follicle. Whether TGF-alpha continues to be produced in those follicles that go on to ovulate and form a corpus luteum is currently under investigation. In the present study, TGF-alpha was localized in the bovine corpus luteum by means of immunoperoxidase staining using a monoclonal antibody for TGF-alpha that does not cross-react with epidermal growth factor.

Steroidogenesis-inducing protein interacts with transforming growth factor-beta to stimulate DNA synthesis in rat granulosa cells.

We have examined the effects of steroidogenesis-inducing protein (SIP), previously isolated from human follicular fluid, on the synthesis of DNA by granulosa cells isolated from diethylstilbestrol-primed immature rats. SIP alone had no effect but in conjunction with transforming growth factor-beta (TGF-beta) there was an increase in [3H]thymidine incorporation into granulosa cell DNA. The increase in [3H]thymidine into DNA was due to an increase in the number of labeled granulosa cells as assessed by autoradiography.

Interleukin-1 stimulates deoxyribonucleic acid synthesis in immature rat Leydig cells in vitro.

The number of interstitial macrophages in the testis fluctuates according to age, increasing gradually during prepubertal development to reach 15-20% in the interstitial compartment in the adult rat. These macrophages are in close morphological association with Leydig cells. Macrophage products, interleukin-1 (IL-1) and tumor necrosis factor alpha stimulate and/or inhibit steroid production in cultures of Leydig cells.

Immunohistochemical localization of transforming growth factor-beta 1 and -beta 2 during follicular development in the adult rat ovary.

The transforming growth factors-beta (TGF-beta) affect the metabolic activities of each of the cell types in the ovary. In vitro studies using immature rat ovaries have shown the expression of TGF-beta 1 and/or TGF-beta 2 mRNA in thecal/interstitial cells and in granulosa cells (Mulheron and Schomberg, 1990; Mulheron et al., 1991).

Growth factor requirements for DNA synthesis by Leydig cells from the immature rat.

Puberty in the male is dependent upon the elevated production of testosterone by the Leydig cells. LH affects this increase in testosterone output by increasing the total number of Leydig cells in the testis and by stimulating the steroidogenic pathway in these cells. Since Leydig cell proliferation is a prerequisite for the onset of puberty, we have examined the ability of LH and growth factors known to be present in the testis to promote DNA synthesis.

Steroidogenesis-inducing protein promotes deoxyribonucleic acid synthesis in Leydig cells from immature rats.

A protein [steroidogenesis-inducing protein (SIP)] has been isolated from human ovarian follicular fluid and shown previously to stimulate steroidogenesis in Leydig cells, adrenal cells, and early luteal cells. Since proteins and peptides known to regulate steroidogenesis, such as gonadotropins and growth factors, also influence the growth of gonadal cells, the present study was designed to assess the effects of SIP on the synthesis of DNA by Leydig cells in vitro. Leydig cells were isolated from 10- and 20-day-old rats and cultured in serum-free medium for 48 h.

Estradiol-17 beta stimulates DNA synthesis in rat granulosa cells: action mediated by transforming growth factor-beta.

Estradiol-17 beta is a mitogen in vivo for the proliferation of granulosa cells in the rat ovary. In this study we have shown that estradiol-17 beta acts on cultures of immature rat granulosa cells to stimulate DNA synthesis. DNA synthesis stimulated by estradiol-17 beta was enhanced by FSH.