Polycystic ovary syndrome: interaction of follicle stimulating hormone and polypeptide growth factors in oestradiol production by human granulosa cells

Loss of Estrogen Receptors is Associated with Increased Tumor Aggression in Laryngeal Squamous Cell Carcinoma

Laryngeal squamous cell carcinoma (LSCC) responds to 17β-estradiol via estrogen-receptor (ER, transcribed from ESR1) dependent mechanisms, but is not recognized as a hormonally responsive cancer. 17β-estradiol production by LSCC cell lines UM-SCC-11A and UM-SCC-12 was examined. Wild type (WT) and ESR1-silenced LSCC cultures and xenografts were examined for 17β-estradiol responsiveness in vivo. 14 LSCC and surrounding epithelial samples at various pathological stages were obtained from patients; ERα and ERβ expression were verified using data from the total cancer genome atlas. UM-SCC-11A and UM-SCC-12 both produce 17β-estradiol, but only UM-SCC-12, not UM-SCC-11A, xenograft tumors grow larger in vivo in response to systemic 17β-estradiol treatments. ERα66 and ERα36 expression inversely correlated with clinical cancer stage and tumor burden. LSCC ERα66 expression was higher compared to surrounding epithelia in indolent samples but lower in aggressive LSCC. ERβ expression was highly variable. High ESR1 expression correlated with improved survival in LSCC. Loss of ERα66 expression inversely correlated with prognosis in LSCC. ERα66 may be a histopathological marker of aggression in LSCC.

The role of intraovarian regulators in the aetiology of polycystic ovarian syndrome

The present review demonstrates that the availability of bioactive FSH and LH in PCOS is normal and that granulosa cells of PCO are not apoptotic and instead hyperexpress functional FSH receptors and may possess intact aromatase activity. Consequently, these cells respond excessively to exogenous FSH stimulation and produce high amounts of oestradiol bothin vivoandin vitro. The altered developmental capacity of follicles from PCOin vivois most likely due to the abnormal follicular milieu of PCO and the culminating effects of intrafollicular inhibitors and stimulators. The failure of ovarian oestradiol production and follicular maturation to dominancein vivomay be due to a mechanism that interferes with the function of FSH, such as intraovarian steroids and growth factors. It has previously been shown that EGF and TGFα have inhibitory actions on follicular development, aromatization and LH receptor formation. In contrast, EGF enhances early follicular recruitment and growth. Therefore, it is hypothesized that EGF/TGFα may have a causal relationship in the mechanisms of anovulatory infertility in women with PCOS. Thus, an aberration in the regulation of follicular fluid EGF and/or TGFα may result in reduced numbers of granulosa cells, cessation of follicle selection and ultimately in the creation and maintenance of PCOS. The exact mechanism by which the hyperfunction of EGF/TGFα occurs and the trigger for this hyperactivity in the ovary remain to be determined. An experimental animal model may be required to assist such investigations in the future.

Function of the polycystic ovary

The mechanism of the increase in the number of follicles in polycystic ovaries (PCO) is still not understood, but most data indicate that folliculogenesis is abnormal at all stages. This increase is probably due to prolonged follicle growth in both ovulatory (ov) and anovulatory PCO (anovPCO) rather than over-recruitment from the primordial stage. There appear to be fewer follicles in ovPCO than in anovPCO and this may be due to slow growth combined with arrested development in the anovPCO, preventing the normal process of atresia. This idea is supported by data indicating that the preponderance of structures in anovPCO are functional follicles rather than atretic cysts. In contrast, follicles in ovPCO are primarily atretic, analogous to the situation in the normal ovary. Closer analysis of the function of these follicles reveals an intrinsic defect in the theca cell layer in the expression of the genes encoding steroidogenic enzymes. Although androgen production is increased in all PCOs, the serum concentrations of androgen tended to be higher in anovulatory women indicating that there may be a link between the ovarian concentration and anovulation. Granulosa cells in small follicles from anovPCO behave in a similar fashion to those in preovulatory follicles from normal ovaries in terms of steroidogenic responses. This, in combination with the finding of LH-responsiveness in small follicles from anovPCO, has led to the suggestion that these follicles are prematurely luteinized. The recent finding that follistatin gene regulation may be abnormal in women with polycystic ovary syndrome (PCOS) provides a new insight into the possible defect in the function of these ovaries. Elucidation of the precise nature of the defect may provide the key to understanding the apparent contradiction of increased steroidogenesis in the presence of abnormal and arrested follicle growth.

Metformin directly inhibits androgen production in human thecal cells

OBJECTIVE

To examine the direct effect of metformin on thecal cell androgen production.

SETTING

Basic science research laboratory, University of Texas Southwestern, Dallas, Texas.

INTERVENTION(S)

Human ovarian theca-like tumor cells were treated with various concentrations of metformin in the presence and absence of forskolin for 48 hours.

MAIN OUTCOME MEASURE(S)

Media were collected, and radioimmunoassay (RIA) for progesterone, 17 alpha-hydroxyprogesterone (17OHP), androstenedione, and testosterone was performed. The effect of metformin on the expression of various enzymes involved in theca cell steroidogenesis was examined.

RESULT(S)

Metformin (50 microM and 200 microM) significantly inhibited androstenedione production from both forskolin-stimulated and unstimulated theca cells. Testosterone production was also significantly inhibited in forskolin-treated cells in the presence of 200 microM of metformin-treated compared with forskolin-only-treated cells. Western blot analysis revealed that metformin significantly inhibited the expression of steroidogenic acute regulatory (StAR) protein and 17 alpha-hydroxylase (CYP17) expression in cells stimulated with forskolin compared with forskolin treatment alone. There was no significant change in either 3beta-hydroxysteroid dehydrogenase (3 beta HSD) or cholesterol side-chain cleavage (CYP11A1) protein expression. Northern analysis revealed a significant decrease in the expression of CYP17 mRNA in forskolin-stimulated cells treated with metformin (200 microM) compared with forskolin-only-treated cells, however, there was no significant change in steroidogenic acute regulatory protein mRNA expression.

CONCLUSION(S)

Our results suggest that metformin may have a direct effect on thecal cells' androgen production.

Systemic treatment in the rat with epidermal growth factor causes polycystic growth of the ovaries

BACKGROUND

It has previously been suggested that epidermal growth factor (EGF) plays a role in the function of the ovary. We administered systemic EGF to assess the influence of EGF receptor stimulation on the morphology of the ovaries.

METHODS

Forty-eight female Wistar rats were allocated to five groups receiving EGF treatment (150 microgram/kg/day) for 0 (controls), 1, 2, 3 and 4 weeks. All rats were exactly 8 weeks at the start of the experiment and 12 weeks at sacrifice. The EGF was administered in the weeks prior to sacrifice. At sacrifice, the perfusion-fixed ovaries were removed and weighed, and the volumes of tissue components were quantified using stereology.

RESULTS

EGF administration increased the total weight of the ovaries from 129 +/- 18 mg in the controls to 158 +/- 29 mg (p<0.05) after one week. In subsequent weeks the total weight increased to 230 +/- 73 mg (p<0.001). The weight gain after one week of treatment was exclusively due to a fourfold increase in follicular cyst volume (p<0.01). In subsequent weeks the cyst volume was increased up to eightfold. After 2, 3 and 4 weeks of treatment the quantity of luteinizing cells was likewise increased by 70% (p<0.01).

CONCLUSION

EGF administration causes the follicular cells to produce cysts and increases the quantity of luteinizing cells.

Effect of gonadotropins, insulin and IGF I on granulosa luteal cells from polycystic ovaries

The aim of this work is to evaluate the gonadotropin and growth factor effects in vitro on steroidal response in human granulosa luteal cells from polycystic ovaries compared with normal granulosa luteal cells in humans. The granulosa cells from polycystic (polycystic ovarian granulosa cells, POGC) and normo-ovulating women (normal cells, NC) were collected in the preovulatory phase after oocyte retrieval during the GIFT program. The cells were cultured serum-free for 24, 48 and 96 h. Estradiol and progesterone production was determined with or without HCG (1-200 ng/ml), FSH (10-300 ng/ml), insulin (1-50 micrograms/ml) and IGF I (1-50 ng/ml) addition. All treatments significantly induced a 2-3 fold estradiol increase at the 48-h and 96-h time points in POGC. The progesterone production was unaffected by HCG, FSH, insulin and IGF I addition, respectively, in POGC, whereas the NC were responsive at the 48-h and 96-h time points. FSH did not stimulate progesterone production in granulosa cells either from polycystic or normovulating subjects. Our findings indicate that POGC are hypersensitive to all substances in terms of estradiol production, whereas they show a reduced capacity of progesterone production with some treatments.

Inhibitory effects of insulin-like growth factor-binding proteins on steroidogenesis by human granulosa cells in culture

The effects of insulin-like growth factor-binding proteins (IGFBPs) 1 and 3 on steroidogenesis by human granulosa cells has been examined. Both IGFBP-1 and IGFBP-3 produced a dose-related inhibition of IGF-I-stimulated oestradiol accumulation in granulosa cell-conditioned medium with complete reversal of the effects of IGF-I in the presence of a molar excess of binding protein. IGFBPs 1 and 3 also exerted a small (25-40%) but significant and consistent inhibition of oestradiol secretion in response to follicle-stimulating hormone (FSH) alone. The progesterone response to IGF-I was inhibited by IGFBPs 1 and 3 but there was no effect on FSH-stimulated progesterone production. These data support the concept of a physiologically important intraovarian IGF system in the human ovary and demonstrate an unequivocally inhibitory effect of IGFBPs 1 and 3 on IGF-I-stimulated granulosa cell steroidogenesis.