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Emerging evidence suggests that the Notch/Delta-like ligand 4 (Dll4) pathway may offer important new targets for antiangiogenesis approaches. In this study, we investigated the clinical and biological significance of Dll4 in ovarian cancer. Dll4 was overexpressed in 72% of tumors examined in which it was an independent predictor of poor survival. Patients with tumors responding to anti-VEGF therapy had lower levels of Dll4 than patients with stable or progressive disease. Under hypoxic conditions, VEGF increased Dll4 expression in the tumor vasculature. Immobilized Dll4 also downregulated VEGFR2 expression in endothelial cells directly through methylation of the VEGFR2 promoter. RNAi-mediated silencing of Dll4 in ovarian tumor cells and tumor-associated endothelial cells inhibited cell growth and angiogenesis, accompanied by induction of hypoxia in the tumor microenvironment. Combining Dll4-targeted siRNA with bevacizumab resulted in greater inhibition of tumor growth, compared with control or treatment with bevacizumab alone. Together, our findings establish that Dll4 plays a functionally important role in both the tumor and endothelial compartments of ovarian cancer and that targeting Dll4 in combination with anti-VEGF treatment might improve outcomes of ovarian cancer treatment. Cancer Res; 71(18); 6030–9. ©2011 AACR.

Continuous efforts have been devoted to unraveling the biophysiology and development of the human fetal adrenal cortex, which is structurally and functionally unique from other species. It plays a pivotal role, mainly through steroidogenesis, in the regulation of intrauterine homeostasis and in fetal development and maturation. The steroidogenic activity is characterized by early transient cortisol biosynthesis, followed by its suppressed synthesis until late gestation, and extensive production of dehydroepiandrosterone and its sulfate, precursors of placental estrogen, during most of gestation. The gland rapidly grows through processes including cell proliferation and angiogenesis at the gland periphery, cellular migration, hypertrophy, and apoptosis. Recent studies employing modern technologies such as gene expression profiling and laser capture microdissection have revealed that development and/or function of the fetal adrenal cortex may be regulated by a panoply of molecules, including transcription factors, extracellular matrix components, locally produced growth factors, and placenta-derived CRH, in addition to the primary regulator, fetal pituitary ACTH. The role of the fetal adrenal cortex in human pregnancy and parturition appears highly complex, probably due to redundant and compensatory mechanisms regulating these events. Mounting evidence indicates that actions of hormones operating in the human feto-placental unit are likely mediated by mechanisms including target tissue responsiveness, local metabolism, and bioavailability, rather than changes only in circulating levels. Comprehensive study of such molecular mechanisms and the newly identified factors implicated in adrenal development should help crystallize our understanding of the development and physiology of the human fetal adrenal cortex.

Purpose: Metronomic chemotherapy regimens have shown anti-tumor activity by anti-angiogenic mechanisms, however, the efficacy of metronomic topotecan in ovarian cancer is not known and the focus of the current study. Experimental Design: In vivo dose-finding and therapy experiments with oral metronomic topotecan were performed in an orthotopic model of advanced ovarian cancer. Tumor vascularity (MVD: CD31), proliferation (PCNA), and apoptosis (TUNEL) were examined among treatment arms. In vitro experiments including MTT and western blot analysis were performed to identify specific anti-angiogenic mechanisms of topotecan. Results: Compared to controls, metronomic (0.5, 1.0 and 1.5 mg/kg; daily) and maximum tolerated therapy (MTD; 7.5 and 15 mg/kg; weekly) dosing regimens reduced tumor growth in dose-finding experiments, but significant morbidity and mortality was observed with higher doses. Metronomic and MTD topotecan therapy significantly reduced tumor growth in both HeyA8 and SKOV3ip1 models: 41-74% (metronomic), and 64-86% (MTD dosing) (p

Therapeutic strategies based on antiangiogenic approaches are beginning to show great promise in clinical studies. However, full realization of these approaches requires identification of key differences in gene expression between endothelial cells from tumors versus their normal counterparts. Here, we examined gene expression differences in purified endothelial cells from 10 invasive epithelial ovarian cancers and 5 normal ovaries using Affymetrix U133 Plus 2.0 microarrays. More than 400 differentially expressed genes were identified in tumor-associated endothelial cells. We selected and validated 23 genes that were overexpressed by 3.6- to 168-fold using real-time reverse transcription-PCR and/or immunohistochemistry. Among these, the polycomb group protein enhancer of Zeste homologue 2 (EZH2), the Notch ligand Jagged1, and PTK2 were elevated 3- to 4.3-fold in tumor-associated endothelial cells. Silencing these genes individually with small interfering RNA blocked endothelial cell migration and tube formation in vitro. The present study shows that tumor and normal endothelium differ at the molecular level, which may have significant implications for the development of antiangiogenic therapies. [Cancer Res 2007;67(4):1757–68]

Ascites formation associated with neoplasms is most likely due to increased vascular permeability, a process in which vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) plays a pivotal role. We hypothesized that tumor-derived VEGF/VPF modulates ascites formation through a paracrine effect on both tumor and peritoneal vessels. We investigated human vascular endothelial permeability using a newly developed dual-chamber permeability assay by co-culturing human umbilical vein cells with and without ovarian cancer cell lines (OVCAR-3, Hey-A8, and OCC-1) in the presence or absence of a human VEGF monoclonal antibody and VE-cadherin function–blocking antibody. This method permits determination of mechanisms by which substances released from neoplasms and other sources of vascular endothelial cell secretagogues modulate vascular permeability and likely other pathologic states.

Context: Matricellular proteins are a group of secreted, multifunctional extracellular matrix glycoproteins that includes thrombospondins (TSPs), tenascin-C, and secreted protein acidic and rich in cysteine (SPARC). They may be implicated in the dynamic developmental processes of the human fetal adrenal (HFA) in which the outer, definitive zone (DZ) cells are postulated to proliferate, migrate centripetally, differentiate, and populate the inner, steroidogenic fetal zone (FZ).Objective: The objective of the study was to identify a matricellular molecule that likely plays a major role in HFA development.Design: Studies involved RNA, cryosections, and cell cultures from 14- to 23-wk HFAs and human adult adrenal RNA.Main Outcome Measures: Measures included transcripts encoding matricellular proteins, using real-time quantitative RT-PCR; SPARC localization by immunostaining; and ACTH regulation of SPARC expression and secretion by quantitative RT-PCR and Western blot.Results: SPARC HFA mRNA was 100-, 700-, and 300-fold higher than TSP-1, TSP-2, and tenascin-C mRNA, respectively. HFA SPARC mRNA was 3-fold higher than adult adrenals (P < 0.005), comparable with levels in adult brain (positive control), whereas mRNAs encoding TSP-1 and TSP-2 were lower in fetal than adult adrenals. SPARC immunoreactivity was detected exclusively in the FZ, not DZ. ACTH, a key regulator of HFA growth and function, increased SPARC mRNA (by 1.7-fold at 1 nm, 48 h, P < 0.05) in isolated FZ cells but not DZ cells. ACTH up-regulation of SPARC protein was also detected in FZ cell lysates and culture medium.Conclusions: Results suggest a possible role for SPARC in development of functional and/or structural zonation of the HFA.

Organogenesis is a coordinated process involving cell replication, differentiation, adhesion, and migration. We seek to understand the complex developmental signals involved in the ontogeny of the human fetal adrenal gland. The gland is comprised initially of two zones, the definitive and fetal zones. A third zone, the transitional zone, develops between them after midgestation. We have suggested that the definitive zone is comprised of a pool of progenitor cells that proliferate and differentiate into cells of the transitional and fetal zones. However, it has not been possible to demonstrate that definitive zone cells have this capacity because of the absence of protein markers unique to these cells; thus, they could not be purified or positively identified. We sought to identify definitive and fetal zone markers to facilitate cell sorting and identify molecules of biological interest in adrenal development. We performed subtractive hybridization, in situ hybridization, and immunofluorescence to identify unique markers of definitive zone cells. NovH and metallopanstimulin were identified by subtraction hybridization, primarily in the definitive zone. P-Glycoprotein, also principally on definitive zone cells, and the low density lipoprotein (LDL) receptor, predominantly on fetal zone cells, were identified by immunofluorescence. Identification of cellular markers unique to each zone of the fetal adrenal gland will enhance the ability to characterize the proliferative potential of definitive zone cells and assess their capacity to differentiate into cells of the transitional and fetal zones. Purified cells also will permit detailed molecular and mechanistic studies of regulation of human fetal adrenal development.

Background: Lysophosphatidic acid (LPA), at concentrations present in ascitic fluid, indirectly stimulates the growth of malignant ovarian tumors by increasing the expression of vascular endothelial growth factor (VEGF) in ovarian cancer cells. We investigated whether LPA could also directly promote ovarian tumor growth by increasing the level of cyclin D1, a key G1-phase checkpoint regulator, which thereby increases cell proliferation. Methods: Expression of cyclin D1 and LPA receptors (EDG4 and EDG7) was determined in six ovarian cancer cell lines (including OVCAR-3 cells) and immortalized ovarian surface epithelial cells (IOSE-29). Cyclin D1 promoter activity was measured in LPA-treated OVCAR-3 cells cotransfected with cyclin D1 promoter-driven luciferase constructs and cDNA expression plasmids for IBM (a nuclear factor B [NFB] superrepressor). Results: Four of six cancer cell lines, including OVCAR-3, overexpressed cyclin D1 protein relative to levels in IOSE-29 cells. LPA treatment increased cyclin D1 protein in a dose- and time-dependent manner in OVCAR-3 cells but not in IOSE-29 cells. LPA stimulated cyclin D1 promoter activity (3.0-fold, 95% confidence interval [CI] = 2.7-fold to 3.3-fold). Mutation of the NFB-binding site in the cyclin D1 promoter to block NFB binding and expression of IBM, which binds NFB and inhibits its binding to the promoter, markedly diminished LPA stimulation of cyclin D1 promoter activity (activity stimulated only 1.4-fold, 95% CI = 1.1-fold to 1.7-fold, and 0.7-fold, 95% CI = 0.6-fold to 0.8fold, respectively). EDG4 was overexpressed in all cancer cell lines studied relative to that in IOSE-29 cells, but EDG7 was overexpressed in only two lines. Conclusions: Dual mechanisms are probably involved in LPA stimulation of ovarian tumor growth in vivo. In addition to the previously characterized indirect mechanism that increases angiogenesis via VEGF, LPA may directly increase the level of cyclin D1 in ovarian cancer cells, increasing their proliferation. [J Natl Cancer Inst 2003;95:733–40]

During placental development, vessel formation occurs initially by vasculogenesis and subsequently by branching and nonbranching angiogenesis. We investigated vascular endothelial growth factor (VEGF)-A, angiopoietin (Ang)-1 and -2 transcript profiles, and the protein products that they encode in placentas from normotensive pregnancies throughout pregnancy. In addition, we compared these genes in placentas from normotensive women and those with preeclampsia during the third trimester. Quantitative real-time PCR analysis demonstrated that VEGF-A and Ang1 mRNA increased in a linear pattern by 2.5 (not significant) and 2.8%/wk (P = 0.034), respectively, whereas Ang2 decreased logarithmically by 3.5%/wk (P = 0.0003). Ang2 mRNA was 400- and 100-fold higher than Ang1 and VEGF-A, respectively, in the first trimester and declined to 20-fold and 7-fold in the third. Ang2 protein (ELISA) decreased by 4.7%/wk (P = 0.0001), whereas Ang1 and VEGF-A were undetectable. In preeclampsia compared with normotensive pregnancy, only VEGF-A mRNA increased significantly, by 3-fold (P = 0.006). This increase may be related to low oxygen tension, as VEGF-A is up-regulated by hypoxia. In situ hybridization and immunohistochemical studies revealed that VEGF-A was localized in cyto- and syncytiotrophoblast and perivascular cells, whereas Ang1 and Ang2 were only in syncytiotrophoblast and perivascular cells in the immature intermediate villi during the first and second trimesters, and mature intermediate and terminal villi during the third trimester. These data suggest that these molecules may play important roles in placental biology and chorionic villus vascular development and remodeling in an autocrine/paracrine manner. The tight correlation between Ang2 mRNA and protein indicates that regulation of placental vascular development occurs at the transcriptional, and not translational, level.

Lysophosphatidic acid (LPA) is a naturally occurring phospholipid that exhibits pleiotrophic biological activities, ranging from rapid morphological changes to long-term cellular effects such as induction of gene expression and stimulation of cell proliferation and survival on a wide spectrum of cell types. LPA binds and activates distinct members of the Edg/LP subfamily of G protein-coupled receptors that link to multiple G proteins including G(i), G(q) and G(12/13) to elicit cellular responses. LPA plays a critical role as a general growth, survival and pro-angiogenic factor, in the regulation of physiological and pathophysiological processes in vivo and in vitro. Our previous work indicates that abnormalities in LPA metabolism and function in ovarian cancer patients may contribute to the initiation and progression of the disease. Thus, LPA could be a potential target for cancer therapy. This review summarizes evidence that implicates LPA in the pathophysiology of human ovarian cancer and likely other types of human malignancies.

In humans, placental corticotropin-releasing hormone (CRH) production has been linked to the determination of gestational length, and a late gestational fall in CRH-binding protein (CRH-BP) has been linked to the onset of parturition. Expression of placental CRH mRNA is limited to primates, and only in man has a circulating CRH-BP been described. As the fall in CRH-BP in late gestation has been associated with parturition in humans, we sought to determine whether a CRH-BP circulated in the plasma of other primates. It is unclear whether maternal plasma CRH concentrations are elevated in New World monkeys and prosimians. We have therefore performed CRH plasma measurements in the blood of pregnant marmosets, in several species of lemur, and in pregnant and fetal rhesus monkeys as a positive control. Using gel chromatography, CRH-BP was detected in the human, gorilla, chimpanzee, orangutan, gibbon, macaque, squirrel monkey, and marmoset, but was absent in the mandrill, spider monkey, and lemur. CRH was detected in the plasma of pregnant marmosets and rhesus monkeys. CRH was also detected in the fetal rhesus monkey, but at lower concentrations than in maternal plasma. CRH immunoreactivity was not detectable in the plasma of pregnant lemurs or in extracts of lemur placenta. In conclusion, a circulating binding protein for CRH exists in all species of apes but occurs variably among New World and Old World monkeys and is absent in lemurs. The variable occurrence of the CRH-BP does not support a role for this protein in the mechanism of parturition in primates. Maternal CRH is elevated in the pregnant marmoset and rhesus, and may play a role in the pregnancy of New and Old World monkeys.

Objective: To review the current literature on the role of vascular endothelial growth factor/vascular permeability factor (VEGF/VPF) in ovarian physiology and pathology. Design: A computerized search was conducted to identify relevant in vitro and in vivo studies published in English. MEDLINE, Current Contents, and the Index Medicus were searched for studies published before January 2000. Result(s): VEGF/VPF is an angiogenic factor and a potent mitogen for vascular endothelium. During reproductive life, VEGF/VPF plays a role in the cyclic growth of ovarian follicles and corpus luteum development and maintenance, mediating ovarian angiogenesis. VEGF/VPF expression and secretion are induced by both FSH and LH/hCG receptor-activated pathways. Conclusion(s): VEGF/VPF expression and production within the ovary are critical for normal reproductive function. Defects in angiogenesis may contribute to a variety of disorders including anovulation and infertility, pregnancy loss, ovarian hyperstimulation syndrome, and ovarian neoplasms.

Several investigators have noted that hormone-dependent development of endometriosis implants lags behind that of simultaneously analysed eutopic endometrium. With the recent discovery of the oestrogen receptor-beta (ER-beta) isoform, the aim of this study was to investigate whether differences in the expression of ER-alpha and ER-beta might explain this observation. mRNA transcripts from endometrial stromal cells isolated from normal endometrium (NE) and from endometriomas (EI) were analysed using a semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) technique. RT-PCR and Southern blot analyses of the two ER isoforms indicated that NE and EI stromal cells predominantly express ER-alpha mRNA, however the relative concentrations of ER isoform mRNA transcripts differed between the two cell types. Steady-state ER-alpha:ER-beta mRNA ratios were 15.5 +/- 2.8 and 5.2 +/- 0.9 respectively for NE and EI cells (P = 0.02). NE and EI stromal cells expressed ER proteins with similar Kd ( approximately 0.9 nM) and densities ( approximately 24 500 binding sites/cell) respectively. Functional ER expression was indicated by an increase in progesterone receptor concentrations of approximately 60% (P = 0.03) after incubation with 10 nM oestradiol. We postulate that differential transcript processing, ligand specificity and biological actions of the ER-alpha and -beta isoforms may influence differential growth responses in normal and ectopic endometrium.

Phytoestrogens influence a variety of biological processes. As 17beta-estradiol alters adrenocortical cell function, we examined whether the dietary phytoestrogens, genistein and daidzein, have related effects. In cultured human fetal and postnatal adrenal cortical cells, genistein and daidzein (both 0.4-40 micromol/L) decreased ACTH-stimulated cortisol production to basal levels (ED50, 1-4 micromol/L). In the adult adrenocortical cell line, H295, genistein, daidzein, and 17beta-estradiol (10 micromol/L) decreased cAMP-stimulated cortisol synthesis in a similar fashion. Neither genistein nor daidzein altered basal or ACTH-stimulated dehydroepiandosterone sulfate (DHEA-S) production in fetal adrenocortical cells, whereas in postnatal adrenocortical cells, DHEA and DHEA-S were markedly increased (ED50, 1-4 micromol/L). In H295 cells, basal and cAMP-stimulated DHEA production were similarly increased by the phytoestrogens and 17beta-estradiol. Genistein and daidzein did not affect the expression of steroid-metabolizing enzymes. However, genistein and daidzein specifically inhibited the activity of 21-hydroxylase (P450c21); the activities of other steroidogenic enzymes were not affected. Thus, phytoestrogens may decrease cortisol synthesis by suppressing the activity of P450c21 and, as a consequence, increase DHEA/DHEA-S synthesis by shunting metabolites away from the glucocorticoid synthetic pathway. Therefore, consumption of foods containing phytoestrogens may alter adrenocortical function by decreasing cortisol and increasing androgen production.

After 10–15 weeks of gestation, the human fetal adrenal cortex undergoes rapid growth due to enlargement of a specialized cortical compartment known as the fetal zone (FZ). Soon after birth, the FZ regresses and the adult zonation pattern develops at least in part from cells derived from the persistent definitive zone (DZ), a thin layer of tightly packed cells surrounding the FZ. We postulated that growth of the fetal adrenal cortex involves zone-specific cellular hyperplasia, whereas the postnatal involution of the FZ is due to apoptosis. Therefore, we investigated the pattern of cellular proliferation and death in the FZ and DZ of the human fetal and postnatal adrenal cortex using immunohistochemical staining for proliferating cell nuclear antigen as a marker of mitosis and in situ detection of DNA fragmentation as a marker of apoptosis. Between 10–14 weeks’ gestation, the mitotic indexes (percentage of proliferating cell nuclear antigen-positive cells) in the DZ (26.46 ± 2.95%) and in the FZ (21.26 ± 2...

Ovarian cancer is characterized by the rapid growth of solid intraperitoneal tumors and large volumes of ascitic fluid. Vascular endothelial growth factor (VEGF) augments tumor growth by inducing neovascularization and may stimulate ascites formation by increasing vascular permeability. We examined the role of VEGF in ovarian carcinoma using in vivo models in which intraperitoneal or subcutaneous tumors were induced in immunodeficient mice using the human ovarian carcinoma cell line SKOV-3. After tumor engraftment (7 to 10 days), some mice were treated with a function-blocking VEGF antibody (A4.6.1) specific for human VEGF. A4.6.1 significantly (P < 0.05) inhibited subcutaneous SKOV-3 tumor growth compared with controls. However, tumor growth resumed when A4.6.1 treatment was discontinued. In mice bearing intraperitoneal tumors (IP mice), ascites production and intraperitoneal carcinomatosis were detected 3 to 7 weeks after SKOV-3 inoculation. Importantly, A4.6.1 completely inhibited ascites production in IP mice, although it only partially inhibited intraperitoneal tumor growth. Tumor burden was variable in A4.6.1-treated IP mice; some had minimal tumor, whereas in others tumor burden was similar to that of controls. When A4.6.1 treatment was stopped, IP mice rapidly (within 2 weeks) developed ascites and became cachectic. These data suggest that in ovarian cancer, tumor-derived VEGF is obligatory for ascites formation but not for intraperitoneal tumor growth. Neutralization of VEGF activity may have clinical application in inhibiting malignant ascites formation in ovarian cancer.

Estrogens produced by the placenta play a pivotal role in the endocrine control of pregnancy and induce many of the key changes involved in parturition. The placentae of humans and higher primates use the C19 androgen dehydroepiandrosterone sulfate (DHEA-S) supplied by the fetal adrenals as the principal substrate for estrogen synthesis. Thus, secretion of androgens by the fetal adrenals may be central to the process of primate parturition. The timing of human parturition also is correlated with placental CRH concentrations in the maternal circulation. Because the mechanisms that regulate DHEA-S production by the fetal adrenals are incompletely understood, we examined whether there is a functional relationship between CRH and steroid production by human fetal adrenal cortical cells. Using Northern blot analysis, we detected messenger RNA transcripts (2.7 kb) encoding the type-1 CRH receptor in total RNA extracted from midgestation human fetal adrenals, suggesting that the fetal adrenal cortex may be directly responsive to CRH. To test this, primary cultures of human fetal adrenal cortical cells were exposed to human CRH. Human CRH increased DHEA-S production by cultured human fetal adrenal cortical cells in a dose-dependent fashion, with an ED50 of 10-100 pmol/L. Human CRH was as effective as ACTH at stimulating DHEA-S production; however, it was 70% less potent than ACTH at stimulating cortisol production, indicating that its actions were preferentially directed toward increasing DHEA-S synthesis. Consistent with this thesis, we found that CRH increased abundance of messenger RNA encoding cytochrome P450 cholesterol side-chain cleavage and 17alpha-hydroxylase/17,20 lyase but not 3beta-hydroxysteroid dehydrogenase in adrenal cells. CRH did not alter cell number, indicating that it is not mitogenic for fetal adrenal cortical cells. These data demonstrate a direct functional interaction between CRH and the fetal adrenal. Therefore, placental CRH production, which rises exponentially during human pregnancy, may play a key role in promoting DHEA-S production by the fetal adrenals, which could lead to increasing placental estrogen synthesis and contribute to the process of parturition in humans.

The human adrenal cortex has a complex vasculature that is essential for growth, organ maintenance, and access of secreted hormones to the circulation. Growth and function of the adrenal cortex are regulated by corticotropin (ACTH), the actions of which are in part mediated by locally produced growth factors. As cortical growth and vascularization must increase in a coordinated manner, we hypothesized that ACTH also influences adrenal cortical angiogenesis by stimulating the local expression of specific angiogenic factors. Vascular endothelial growth factor (VEGF) is a potent endothelial cell-specific angiogenic peptide, the expression of which has been detected in adrenal cortical cells. Therefore, we examined the localization of VEGF expression in the midgestation (16–20 weeks) human fetal adrenal cortex and determined whether VEGF expression and secretion by isolated human fetal adrenal cortical cells are regulated by ACTH. By immunohistochemical analysis, strong cytoplasmic staining for VEGF was detected in scattered clusters of fetal zone (inner cortical compartment) cells. In contrast, cells in the outer, definitive zone of the cortex stained only weakly for VEGF. The predominant staining for VEGF in the fetal zone correlated with the extensive vasculature of this zone as detected by immunohistochemical staining for von Willebrand factor, which is specific for endothelial cells. In primary cultures of human fetal adrenal cortical cells, ACTH (1 nmol/L) and forskolin (10 μmol/L) increased the abundance of messenger ribonucleic acid transcripts encoding VEGF, as assessed by Northern and slot blot analyses. The stimulatory effect of ACTH and forskolin on VEGF gene expression occurred within 2 h of agonist exposure and persisted for at least 24 h. ACTH and forskolin also increased VEGF protein secretion by fetal adrenal cortical cells, as assessed by enzyme-linked immunosorbent assay for VEGF in fetal adrenal cortical cell-conditioned medium. A significant (P< 0.05) increase in VEGF secretion was detected as early as 8 h after ACTH or forskolin treatment. By 24 h after the addition of ACTH or forskolin, VEGF secreted from isolated human fetal adrenal cells was increased 5- to 6-fold. These data demonstrate that the human fetal adrenal cortex, particularly the cells of the inner fetal zone, express VEGF and that VEGF expression and secretion by these cells are directly regulated by ACTH and the activation of adenylate cyclase. Thus, VEGF may be a local regulator of adrenal cortical angiogenesis and an important mediator of the tropic action of ACTH, ensuring the coordination of ACTH-stimulated cortical growth and vascularization.

Prebeta-1 HDL is a molecular species of plasma HDL of approximately 67 kDa mass that contains apolipoprotein A-I, phospholipids, and unesterified cholesterol. It participates in a cyclic process involved in the retrieval of cholesterol from peripheral tissues. In this cycle, unesterified cholesterol from cells is incorporated into prebeta-1 HDL, providing a substrate for esterification of cholesterol by lecithin:cholesterol acyltransferase. Prebeta-1 HDL then becomes incorporated into larger HDL species of alpha mobility as esterification proceeds and is regenerated during the transfer of cholesteryl esters from alpha HDL particles to acceptor lipoproteins. Thus the steady state level of prebeta-1 HDL in plasma reflects the relative efficiencies of the major metabolic processes involved in its generation and removal. We have used an isotope dilution technique to measure prebeta-1 HDL levels in the plasmas of 136 normolipidemic individuals (46 M, 90 F). The mean absolute concentration of prebeta-1 HDL as apolipoprotein A-I was 68 ± 40 μg/ml for women, and 84 ± 49 m/ml for men. Prebeta-1 HDL represented 5.5 ± 3.3% of total apolipoprotein A-I in women, and 7.2 ± 4.0% in men. The distributions of both absolute and percent prebeta-1 HDL are highly asymmetric, with skew toward higher values. However, the skew appears not to be attributable to either plasma cholesterol or triglyceride levels which are also skewed in population samples. The percent prebeta-1 HDL was negatively correlated with HDL cholesterol levels (P < 0.0001), whereas absolute levels of prebeta-1 HDL were positively correlated with apolipoprotein A-I and negatively correlated with HDL cholesterol (P, for both, < 0.0001). Multiple linear regression analysis revealed effects of age and gender, but no association with lipoprotein fractions other than HDL. Lower levels of prebeta-1 HDL were associated with female gender in all models.—O'Connor, P. M., B. R. Zysow, S. A. Schoenhaus, B. Y. Ishida, S. T. Kunitake, J. M. Naya-Vigne, P. N. Duchateau, R. F. Redberg, S. J. Spencer, S. Mark, M. Mazur, D. C. Heilbron, R. B. Jaffe, M. J. Malloy, and J. P. Kane. Prebeta-1 HDL in plasma of normolipidemic individuals: influences of plasma, age, and gender.

The rapid growth of the human fetal adrenal gland, which is primarily a reflection of the growth of the unique fetal zone, is regulated by ACTH acting indirectly to stimulate the expression of locally produced growth factors, of which IGF-II and bFGF appear to play key roles. Through most of gestation, the outer definitive zone appears to function as a reservoir of progenitor cells which move centripetally to populate the rest of the gland. At the end of pregnancy, the fetal zone undergoes senescence through an apoptotic process. Activin and TGF-beta are capable of inducing apoptosis in the fetal zone. Corticotropin-releasing hormone, which is produced by the placenta in markedly increased amounts at the end of gestation, may orchestrate a variety of processes, including direct stimulation of fetal adrenal steroidogenesis, culminating in the initiation of parturition.

Insulin-like growth factor (IGF)-binding proteins (IGFBPs) antagonize IGF and gonadotropin actions on granulosa cells. Human atretic follicles express IGFBP-2 in granulosa cells more strongly and contain higher levels of IGFBP-2 and IGFBP-4 than healthy follicles. We studied the effects of interferon-γ (IFNγ) and activin A, which decrease progesterone accumulation, on granulosa cell IGFBP production and apoptosis. Conditioned media from luteinizing granulosa cells cultured with IFNγ or activin A and/or LH were subjected to ligand blotting; northern blots of total ribonucleic acid (RNA) from these cells were probed for IGFBP-2 and -4. Apoptosis was measured by in situ DNA end labeling. LH decreased medium IGFBP-2 to 21% of the control value. Although IFNγ did not alter basal medium IGFBP-2, in the presence of LH it increased IGFBP-2 3.4-fold, with parallel changes in messenger RNA levels. Activin A also tended to increase medium IGFBP-2 in LH-treated cultures. In conditioned medium, IGFBP-4 was consistently decreased by LH, whereas both IFNγ and activin A increased IGFBP-4 and decreased IGFBP-4 protease activity. Both LH and IFNγ modestly stimulated IGFBP-4 messenger RNA levels. Follistatin antagonized the action of activin A, but not that of IFNγ. IFNγ, but not activin A, increased granulosa cell apoptosis. In conclusion, IFNγ produced by activated lymphocytes may decrease endogenous IGF activity through stimulation of IGFBPs and may promote apoptosis of granulosa-lutein cells in vivo and, thus, luteal regression. Activin A similarly promotes IGFBP accumulation, but it does not promote apoptosis. (J Clin Endocrinol Metab 83: 179–186, 1998)

Previous studies of raloxifene conducted in animal models and postmenopausal women have demonstrated antiestrogenic action on the endometrium. The purpose of this first study of raloxifene in women with normal menstrual cycles was to determine its reproductive endocrine and endometrial effects. In part I, raloxifene (400 mg) was administered for 5 days in the follicular, periovulatory, or luteal phase of the menstrual cycle (n = 12). In part II, women were randomized to receive raloxifene (100 or 200 mg) for 28 days beginning on day 3 of the cycle (n = 19). All women ovulated in both parts of the study. Raloxifene did not alter the length of the menstrual cycle or the day of the LH surge. A 5-day course of raloxifene administered in any phase of the cycle elevated FSH area under the curve (AUC) for the entire cycle and estradiol AUC for the second half of the cycle compared with those in control cycles. In part II, raloxifene also appeared to increase the FSH AUC and estradiol AUC. Raloxifene decreased the number of gland mitoses in follicular phase endometrial biopsies. Subtle effects suggestive of gland-stromal dysynchrony were noted in a limited number of the secretory phase endometrial biopsies. This study has demonstrated that 1) raloxifene does not prevent ovulation in women with normal menstrual cycles; 2) ovarian estrogen production will continue, and in some cases increase, in response to raloxifene; and 3) antiestrogenic effects of raloxifene on the endometrium are subtle in the endocrine milieu of normal to high circulating estradiol concentrations.

The unique characteristics of the primate (particularly human) fetal adrenal were first realized in the early 1900s when its morphology was examined in detail and compared with that of other species. The unusual architecture of the human fetal adrenal cortex, with its unique and disproportionately enlarged fetal zone, its compact definitive zone, and its dramatic remodeling soon after birth captured the interest of developmental anatomists. Many detailed anatomical studies describing the morphology of the developing human fetal adrenal were reported between 1920 and 1960, and these morphological descriptions have not changed significantly. More recently, it has become clear that fetal adrenal cortical growth involves cellular hypertrophy, hyperplasia, apoptosis, and migration and is best described by the migration theory, i.e. cells proliferate in the periphery, migrate centripetally, differentiate during their migration to form the functional cortical zones, and then likely undergo apoptosis in the center of the cortex. Consistent with this model, cells of intermediate phenotype, arranged in columnar cords typical of migration, have been identified between the definitive and fetal zones. This cortical area has been referred to as the transitional zone and, based on the expression of steroidogenic enzymes, we consider it to be a functionally distinct cortical zone. Elegant experiments during the 1950s and 1960s demonstrated the central role of the primate fetal adrenal cortex in establishing the estrogenic milieu of pregnancy. Those findings were among the first indications of the function and physiological role of the human fetal adrenal cortex and led Diczfalusy and co-workers to propose the concept of the feto-placental unit, in which DHEA-S produced by the fetal adrenal cortex is used by the placenta for estrogen synthesis. Tissue and cell culture techniques, together with improved steroid assays, revealed that the fetal zone is the primary source of DHEA-S, and that its steroidogenic activity is regulated by ACTH. In recent years, function of the human and rhesus monkey fetal adrenal cortical zones has been reexamined by assessing the localization and ontogeny of steroidogenic enzyme expression. The primate fetal adrenal cortex is composed of three functionally distinct zones: 1) the fetal zone, which throughout gestation does not express 3 beta HSD but does express P450scc and P450c17 required for DHEA-S synthesis; 2) the transitional zone, which early in gestation is functionally identical to the fetal zone but late in gestation (after 25-30 weeks) expresses 3 beta HSD, P450scc, and P450c17, and therefore is the likely site of glucocorticoid synthesis, and 3) the definitive zone, which lacks P450c17 throughout gestation but late in gestation (after 22-24 weeks) expresses 3 beta HSD and P450scc, and therefore is the likely site of mineralocorticoid synthesis. Indirect evidence, based on effects of P450c21 deficiency and maternal estriol concentrations, indicate that the fetal adrenal cortex produces cortisol and DHEA-S early in gestation (6-12 weeks). However, controversy exists as to whether cortisol is produced de novo or derived from the metabolism of progesterone, as data regarding the expression of 3 beta HSD in the fetal adrenal cortex early in gestation are conflicting. During the 1960s, Liggins and colleagues demonstrated that in the sheep, cortisol secreted by the fetal adrenal cortex late in gestation regulates maturation of the fetus and initiates the cascade of events leading to parturition. Those pioneering discoveries provided insight into the mechanism underlying the timing of parturition and therefore were of particular interest to obstetricians and perinatologists confronted with the problems of preterm labor. However, although cortisol emanating from the fetal adrenal cortex promotes fetal maturation in primates as it does in sheep, its role in the regulation of primate parturition, unlike that in sheep

Development of the human fetal adrenals is characterized by rapid growth and high levels of steroidogenic activity during the latter two-thirds of pregnancy. By midgestation, the human fetal adrenals are composed of two distinct cortical zones: the predominant fetal zone, which occupies 80-90% of the cortical volume and produces large amounts of the delta 5-steroid dehydroepiandrosterone sulfate, and the narrow definitive zone, which surrounds the fetal zone. Late in gestation, the peripheral portion of the fetal zone develops into a third, functionally distinct compartment, the transitional zone, which is the likely site of cortisol synthesis. Soon after birth, the adrenal cortex is remodeled and the fetal zone disappears. The adult cortical zones are thought to arise from the definitive zone, which persists postnatally. Development of the human fetal adrenals is regulated primarily by corticortropin (ACTH) secreted from the fetal pituitary. However, as ACTH is not a mitogen per se, its proliferative actions on human fetal adrenal cortical cells are thought to be mediated by autocrine/paracrine growth factors produced by adrenal cortical cells in response to ACTH. In addition, these growth factors appear to modulate the functional response of fetal adrenal cortical cells to ACTH. The roles of several growth factors, including the insulin like growth factors I and II (IGF-I and IGF-II), epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), activin, inhibin, and the transforming growth factors alpha and beta (TGF-alpha and TGF-beta) have been examined. In cultured human fetal adrenal cortical cells, EGF, bFGF, and IGF-I and -II are mitogenic, whereas activin and TGF-beta inhibit proliferation. IGF-II, activin, and TGF-beta also modulate ACTH-stimulated steroidogenesis. Human fetal adrenal cortical cells express IGF-II, bFGF and the activin/inhibin subunits, and the abundance of mRNAs for each of these factors is up-regulated by ACTH, suggesting that these growth factors are autocrine/paracrine mediators of ACTH action. Thus, although human adrenal development is primarily regulated by ACTH, its actions appear to be mediated/modulated by a cohort of locally expressed growth factors, the net effect of which results in the unique growth and steroidogenic activity of the human fetal adrenal cortex.

The rapid growth of the primate fetal adrenal from midgestation until term is regulated by ACTH secreted by the fetal pituitary. Previous studies suggest that the trophic actions of ACTH are mediated by insulin-like growth factor II (IGF-II) synthesized by fetal adrenal cortical cells. To characterize further the role of IGF-II in the regulation of fetal adrenal growth, we investigated the expression of the messenger RNAs (mRNAs) encoding IGF-I, IGF-II, IGF-I receptor (IGF-IR) and IGF binding protein (IGFBP) 1-6 in the fetal rhesus monkey adrenal in vivo from 109 days of gestation until term (165 +/- 5 days) using in situ hybridization. To assess the role of ACTH in the regulation of expression of the IGF system in vivo, we administered metyrapone (3-7 days) to late gestation fetal rhesus monkeys (n = 4) in utero to increase fetal pituitary ACTH secretion. IGF-II mRNA was abundant in the definitive, transitional and fetal zones of the adrenal cortex from 109 days until term. IGF-IR mRNA was expressed in the definitive, transitional and fetal zones and decreased to nondetectable levels at term. IGFBP-2 and IGFBP-6 mRNAs were expressed in the definitive, transitional, and fetal zones, whereas IGFBP-1, -3, -4, and -5 were not detected in adrenal cells. The effects of increasing ACTH secretion on the growth of the specific zones of the adrenal were determined using morphometric techniques. Metyrapone treatment approximately doubled adrenal weight, which was due to an increase in the area of the definitive, transitional, and fetal zones with decreased cell density of the definitive, transitional, and fetal zones compared with controls and not due to a change in total cell number. Therefore, the increase in adrenal weight after metyrapone treatment was due to hypertrophy of the three cortical zones; there was no effect on adrenal medullary growth. The relative abundance of the mRNAs encoding IGF-II and the IGF-IR was increased after metyrapone treatment, whereas the localization and relative abundance of IGFBP 1-6 mRNAs were not altered by metyrapone treatment. We conclude that the ontogenetic increase in adrenal growth may be regulated, at least in part, by locally synthesized IGF-II, and the cessation of adrenal growth that occurs at term may be mediated by the decrease in the IGF-IR. The adrenal cortical expression of IGFBP-2 and IGFBP-6 suggests that these IGFBPs may modulate the IGF-IGF-IR interaction. Metyrapone treatment, which likely increased fetal pituitary ACTH secretion, causes a coordinated increase in expression of IGF-II and IGF-IR in fetal adrenal cortical cells, which may be an important mechanism of regulation of fetal adrenal cortical growth.

Developmental changes in the responsiveness of the fetal adrenals to corticotropin (ACTH) play an important role in the regulation of the fetal hypothalamic-pituitary-adrenal axis. Responsiveness of adrenal cortical cells to ACTH is dependent on the extent of ACTH receptor expression. Therefore, we examined the localization and regulation of ACTH receptor expression in the midgestation (16-24 weeks) human fetal adrenal cortex. In situ hybridization analysis was used to localize messenger RNA (mRNA) encoding the ACTH receptor in sections of human fetal adrenal glands. Messenger RNA encoding the ACTH receptor was localized in cells from all cortical zones; abundance was higher in definitive zone than in fetal zone cells and was least abundant in the more central portions of the cortex. Regulation of ACTH receptor expression was studied using Northern blot analysis of total RNA extracted from primary cultures of fetal and definitive zone cells. Two major (1.5 and 3.5 kilobases) and, upon stimulation with ACTH, 3 minor (4.0, 6.0 and 10.0 kb) ACTH receptor mRNA transcripts were detected in RNA from fetal and definitive zone cells. In both cell types, ACTH-(1-24) increased the abundance of mRNA encoding the ACTH receptor 10- to 20-fold compared with untreated cells. The effects of ACTH-(1-24) on ACTH receptor expression in fetal zone cells were time- and dose-dependent. The ED50 for the stimulation of ACTH receptor expression by ACTH-(1-24) was 1-10 pM, and maximal response to 0.1 nm ACTH-(1-24) was detected after 12-16 h. Eight-bromoadenosine cAMP and forskolin also stimulated ACTH receptor expression in fetal zone cells and closely mimicked the effects of ACTH-(1-24). In contrast, stimulation of protein kinase C with 12-O-tetradecanoyl phorbol 13-acetate had no effect on ACTH receptor expression. Changes in ACTH receptor expression in response to ACTH-(1-24), cAMP and forskolin were paralleled by changes in expression of the P450 cholesterol side chain cleavage (P450scc) enzyme. These data demonstrate that expression of the ACTH receptor by the human fetal adrenal cortex is up-regulated by its own ligand and that this effect is mediated by a cAMP-dependent mechanism. In addition, the coordinate stimulation of ACTH receptor and P450scc expression by ACTH indicates that the gene for the ACTH receptor is one of a specific cohort of genes regulated by ACTH that are required to facilitate fetal adrenal cortical response to ACTH. ACTH regulation of its own receptor may represent a mechanism by which fetal adrenal responsiveness to ACTH is maintained and possibly enhanced during fetal development.

The physiological role of hypothalamic catecholamines in the regulation of TSH secretion in humans has not been studied extensively. We administered the catecholamine synthesis inhibitor alpha-methyl-p-tyrosine (AMPT) to five women in the early follicular phase (one of menstrual cycle days 2-5) of the menstrual cycle and compared TSH secretion patterns to those in five women at the same time in the cycle who did not receive AMPT. From 0800-1600 h, volunteers had an i.v. line placed, through which blood was withdrawn every 15 min for TSH and PRL determinations. AMPT (500 mg) was administered to the study group at 0800 h and again at 1000 h. Baseline TSH concentrations at 0800 h were not significantly different between the control and treatment groups. In keeping with its characteristic circadian secretion pattern, TSH in the control group was 1.72 +/- 0.23 mIU/L at 0800 h, declined to 1.02 +/- 0.11 mIU/L by 1600 h, and was significantly less than the 0800 h value at all time points beyond 1115 h. The decline in TSH was observed in all five controls. By contrast, TSH in the AMPT group rose from an 0800 h value of 1.99 +/- 0.09 mIU/L to a peak of 3.30 +/- 0.86 IU/L by 1245 h, and was significantly higher than that at 0800 h in the treated group from 1130-1315 h. The increase in TSH was observed in all five women who received AMPT. There were significant differences between the mean TSH concentrations in the AMPT-treated (2.51 +/- 0.09 mIU/L) vs. the control group (1.28 +/- 0.09 mIU/L; P < 0.0001) for the entire study. The effectiveness of AMPT was demonstrated by an elevation of mean PRL concentrations from a baseline of 16.67 +/- 2.55 micrograms/L to a peak of 138.7 +/- 21.6 micrograms/L. We conclude that endogenous catecholamines tonically inhibit TSH secretion in the early follicular phase. These data suggest modulation of TRH by tuberoinfundibular dopamine at the hypothalamic and/or pituitary level.

Activin-A decreases progesterone secretion and aromatase activity in cultured human luteinizing granulosa cells. Follistatin is a binding protein for activin and inhibin produced by granulosa cells and present in follicular fluid. The present study examines the hypothesis that follistatin reverses the actions of activin-A on human granulosa cells. Granulosa cells from women undergoing ovarian stimulation for in vitro fertilization were cultured in defined medium with recombinant human (rh) activin-A and purified porcine follistatin. Follistatin completely reversed the inhibition of basal progesterone production by rh-activin-A, but only when added in a greater than 2:1 molar ratio to activin-A. Although variable effects of activin-A on aromatase activity were observed in these studies, follistatin also antagonized these effects. Follistatin had no effect in the absence of added activin-A. rh-Inhibin-A did not alter steroidogenesis by granulosa cells either with or without added activin-A. Even when added in a 45-fold molar excess, inhibin-A did not displace sufficient activin-A from follistatin to inhibit progesterone secretion. This suggests that the affinity of inhibin-A for follistatin is much lower than that of activin-A, and/or that activin-A bound to follistatin dissociates slowly. alpha 2-Macroglobulin, another activin-binding protein, did not alter the inhibition of progesterone production by activin-A. We conclude that in human granulosa cells, follistatin, but not alpha 2-macroglobulin or inhibin-A, acts to modulate the actions of activin-A. Follistatin and activin may be viewed as components of an autocrine/paracrine system within the human follicle that regulate the differentiated functions of granulosa cells.

Vascular endothelial growth factor (VEGF) is potentially an important regulator of angiogenesis, particularly during the extensive tissue growth and remodeling that occur in utero. In the present study, we have investigated the role of VEGF during human fetal development by analyzing the distribution of VEGF messenger RNA as well as the tissue- and cell-specific localization of VEGF peptide in the human midgestation (16-22 weeks) fetus. As a comparison, we conducted parallel studies on several human adult tissues. Messenger RNA encoding VEGF was detected in all fetal tissues studied and was most abundant in human fetal lung, kidney, and spleen; moderately abundant in heart, adrenal, pancreas, intestine, liver, testis, skin, muscle, and brain; and minimally detected in thymus and placenta. VEGF peptide, detected by immunohistochemistry, always was intracytoplasmic and localized principally in epithelial cells and myocytes, including the smooth muscle cells lining blood vessels. VEGF was not detected in vascular endothelial cells. As the cellular localization of VEGF in several human adult tissues was similar to that found in the cognate fetal tissues, VEGF is probably important not only in angiogenesis, but also in the maintenance of existing vessels. As VEGF was localized primarily in epithelial cells and myocytes and not in endothelial cells, these data are consistent with a paracrine mechanism of action whereby VEGF secreted by nonendothelial cells modulates activities in adjacent vascular endothelium.

Objective: Our purpose was to determine whether basic fibroblast growth factor is present in, and synthesized by, human ovarian epithelial neoplasms and to evaluate the expression of gene for the basic fibroblast growth factor receptor. Study Design: The synthesis of basic fibroblast growth factor and its receptor was investigated in seven primary human ovarian epithelial neoplasms. Neoplastic tissues were homogenized and the cytoplasmic extracts purified by heparin-sepharose chromatography with a linear salt gradient of 0.6 to 3 mol/L sodium chloride in Tris-hydrochloric acid. The in situ synthesis of basic fibroblast growth factor and its receptor was demonstrated by polymerase chain reaction. Total ribonucleic acid was reverse transcribed and then amplified with two oligonucleotide primers specific for the bovine and human basic fibroblast growth factor gene and its human receptor gene. Results: As assessed by both bioassay and radioimmunoassay a peak of basic fibroblast growth factor-like activity was present in all tumors in the chromatographic fractions eluted with 3 mol/L sodium chloride. The mitogenic effect on bovine adrenocortical endothelial cell proliferation varied from 35% to 153% above control cultures. Levels of basic fibroblast growth factor-like immunoreactivity were between 4 and 33 ng/ml. Qualitatively similar results were obtained after purifying the cytoplasmic extract of dispersed human ovarian tumor cells. The mitogenic effect was completely abolished by a specific neutralizing anti-basic fibroblast growth factor antibody. Single major deoxyribonucleic acid bands of the expected size (354 and 661 bp) were detected in all tumors studied. The identity of this material with the human basic fibroblast growth factor sequence was confirmed by restriction enzyme analysis. Conclusion: These data demonstrate that both basic fibroblast growth factor and its receptor are present in and synthesized by human ovarian tumor cells. Thus basic fibroblast growth factor might stimulate their abnormal proliferation through an autocrine mechanism.

Subunits of activin and inhibin and their mRNAs are present in human placental and decidual cells. However, evidence for the presence of intact activin dimers in the human placenta and their regulation has been lacking. Using a monoclonal antibody raised against the human activin-A dimer, we examined the cellular localization of immunoreactive activin-A dimer in human placentas of different gestational ages (8-41 weeks). In addition, we determined the effects of culture and various potential regulators on the cellular accumulation of immunoreactive activin-A dimer in trophoblast cells from human first trimester placentas. Activin-A dimer was found in both cyto- and syncytiotrophoblast cells of all gestational ages studied. Immunoreactive activin-A also was detected in placental Hofbauer cells in first and second trimester placentas as well as in cells of the placental membranes. Exposure of these cells to cAMP, GnRH, activin, inhibin, transforming growth factor-beta, dexamethasone, and interleukin-1 did not significantly change the intensity of immunostaining for activin-A dimer. These results together with previous data suggest that placental cells are a source of activin-A and that activin-A may be a paracrine and/or endocrine regulator of feto-maternal interactions during pregnancy.

The cyclic angiogenesis that occurs uniquely within the female reproductive tract is critical for normal reproduction. Two families of endothelial cell-specific growth factors and their receptors have been identified in the ovary, uterus, and placenta: vascular endothelial growth factor/vascular permeability factor and the angiopoietins. These appear to have complementary actions on the vasculature and to be involved during intrauterine development as well as in the adult. Within the ovary, a complex cascade of events required for angiogenesis may play a role in follicular maturation and selection as well as in normal corpus luteum function. Aberrant expression of angiogenic factors plays a role in a wide variety of abnormalities in the ovary. In the uterus, angiogenesis is required for endometrial growth and remodeling. Peptide growth factors such as vascular endothelial growth factor may serve as local mediators of the effects of reproductive hormones on the endometrial vasculature. Disease states such as dysfunctional uterine bleeding, endometriosis, and endometrial hyperplasia or cancer may be associated with aberrant uterine angiogenesis.

On the basis of the known role of platelet-derived growth factor (PDGF)-BB/PDGF receptor (PDGFR) beta in pericyte regulation, highly specific inhibitors of this target are needed. We tested the efficacy of a highly selective aptamer against PDGF-B with or without anti-VEGF therapy in ovarian cancer models.Bevacizumab inhibited tumor growth by 45% and 48% in the HeyA8 and SKOV3ip1 models, respectively. AX102 had minimal effect on the HeyA8 model, but increased tumor growth in the SKOV3ip1 model. However, bevacizumab plus AX102 was more effective than bevacizumab alone, and resulted in 76-88% inhibition of tumor growth in both models. A longitudinal study in the HeyA8 model using bioluminescence imaging showed that combination of bevacizumab, AX102 and paclitaxel caused tumor reduction by 65% (based on bioluminescence imaging). In the HeyA8 model, MVD and PCNA counts were significantly reduced in the bevacizumab treatment groups, and pericyte coverage was significantly decreased in the AX102 treatment groups. In the SKOV3ip1 model, MVD and PCNA was significantly reduced in the bevacizumab treatment group, and even lower in the bevacizumab and AX102 combination treatment group.The therapeutic efficacy of targeting endothelial cells (bevacizumab) and/or pericytes (PDGF-aptamer, AX102) was examined using HeyA8 and SKOV3ip1 orthotopic models of ovarian cancer metastasis. Following therapy, tumors were examined for microvessel density (MVD), proliferating cell nuclear antigen (PCNA) and vascular maturation (pericyte coverage).Dual targeting of endothelial cells and pericytes holds potential as an anti-vascular therapeutic approach in ovarian carcinoma.

Little is known about the ability of the fetal primate gonads to produce inhibin/activin. We investigated the presence of the alpha-, beta A-, and beta B-subunits of inhibin/activin in fetal human (16-23 weeks gestational age) and rhesus monkey (days 150-157 of gestation; term = 165 days) testes and ovaries by immunocytochemistry. The regulation of alpha-inhibin secretion by gonadotropins was studied in fetal testicular cultures. In the human fetal testis, alpha-subunit immunostaining was found in interstitial and intratubular cells, while beta A- and beta B-subunit immunostaining occurred in clusters of Leydig cells that were clearly demarcated from groups of Leydig cells that were immunonegative. In the late gestational monkey testis, the alpha-subunit was localized in tubular cells, and the beta B-subunit was present in the tubules and interstitium. Testicular cells from midgestation human testes secreted detectable immunoreactive alpha-inhibin in response to FSH and hCG stimulation; alpha-inhibin levels were significantly higher after hCG than FSH. In contrast, levels of alpha-inhibin secreted by rhesus monkey testicular cells were significantly increased by FSH, but not hCG. In the ovary, only weak beta B-subunit immunoreactivity was detected in granulosa cells of a few primary follicles from midgestational human fetal ovaries. In contrast, all three subunits were found in granulosa cells of numerous primary and secondary follicles in the late gestation rhesus monkey ovary. In light of recent evidence that inhibins/activins have actions on gonadal differentiation and growth modulation in vitro, as well as endocrine effects on the fetal pituitary, we propose that these proteins may have intragonadal and endocrine roles in human and subhuman intrauterine gonadal development.

Context: Although the inner fetal zone (FZ) of the midgestation human fetal adrenal (HFA) produces dehydroepiandrosterone sulfate, the function of the outer definitive zone (DZ) remains less clear. We have proposed that the DZ phenotype is that of a pool of progenitor cells, many of which are mitotically active. Recently, we studied HFA expression of a family of vascular endothelial cell-specific angiogenic factors, the angiopoietins (Angs), and demonstrated that Ang2 was localized predominantly in the periphery of the gland. Ang1 stabilizes, whereas Ang2 destabilizes, vessels, increasing responsiveness to angiogenic stimuli such as vascular endothelial growth factor (VEGF)-A and fibroblast growth factor (FGF)-2. Objective: Our objective was to test the hypothesis that the periphery of the HFA is a site of angiogenesis. Design: Studies were conducted involving RNA, frozen sections, and primary cell cultures from midgestation HFAs. Main Outcome Measures: Immunofluorescence, laser capture microdissection, and real-time quantitative RT-PCR were used. Results: Double immunostaining demonstrated that proliferating endothelial cells were limited to the DZ and DZ/FZ border. Ang2 mRNA was primarily expressed in the DZ, whereas Ang1 mRNA was primarily in the FZ. VEGF-A and FGF-2 mRNA levels were higher in the DZ. FGF-2 (10 ng/ml) induced Ang2 mRNA by 4-fold in both zones of cells (P < 0.01, at 24 h), but not Ang1 or VEGF-A mRNA. Conclusion: Data suggest that angiogenesis occurs at the periphery of the HFA. The DZ-predominant expression of Ang2 may be explained, in part, by the parallel pattern of FGF-2 expression.

Previous studies indicated that acute exposure of adrenal cells to adrenocorticotropic hormone (ACTH) markedly stimulates steroidogenic capacity in vitro but also inhibits cell proliferation. However, in vivo, ACTH is known to stimulate adrenal cell growth. To address this discrepancy, we determined the effect of long-term (9-11 days) continuous or intermittent exposure to ACTH on human fetal adrenal cell proliferation and steroidogenesis. Adrenal glands from fetuses 18-22 wk gestation were studied. Fetal zone cells were plated either on plastic or on an extracellular matrix (ECM) in the presence and absence of basic fibroblast growth factor (bFGF) (0.5 ng/ml) and 1 or 10 nM ACTH. As determined by cell counting, bFGF stimulated cell proliferation during 9 days in culture. In the presence of bFGF, the average doubling time decreased from 44 to 30 h on plastic and from 37 to 26 h on ECM. Under these conditions, ACTH did not inhibit cell proliferation. Proliferation of fetal adrenal corticosteroid-producing cells in the ACTH-treated cultures also was assessed by histochemical staining for 3 beta-hydroxysteroid dehydrogenase (3 beta HSD). The number of positive cells increased more than 4-fold between Days 5 and 9 in culture. Continuous treatment with 1 nM ACTH increased dehydroepiandrosterone sulfate (DHAS) production 5- to 10-fold during the first 5 days in culture. Thereafter, the stimulated hormone production decreased over time, although there was still a difference of almost 100-fold between the control and ACTH-treated cultures at the end of 9 days.(ABSTRACT TRUNCATED AT 250 WORDS)

In the rhesus monkey and ovine fetus in utero, aldosterone concentrations do not rise in response to surgical stress, ACTH, or angiotensin-II, all of which are secretagogues for this mineralocorticoid in the adult. To assess the mechanism of this phenomenon in the human fetus, metabolism of pregnenolone and corticosterone by second trimester human fetal adrenal definitive zone and fetal zone tissue was studied. After incubation of fresh tissue with trace amounts of [3H]pregnenolone or [3H]corticosterone, the products of metabolism were separated using high performance liquid chromatography and quantified. The delta 5-3 beta-hydroxysteroids 17-hydroxypregnenolone and dehydroepiandrosterone and their sulfates comprised 85-90% of metabolized pregnenolone. In the fetal zone, cortisol was the predominant secreted delta 4-3-ketosteroid, accounting for 6-8% of the metabolized pregnenolone. In the definitive zone, progesterone and corticosterone were the predominant secreted delta 4-3-ketosteroids, each accounting for about 2% of the metabolized pregnenolone. 11-Dehydrocorticosterone and sulfates were the only metabolites detected after incubation of fetal adrenal tissue with corticosterone. 11-Dehydrocorticosterone accounted for more than 80% of the metabolized corticosterone in the definitive zone and 50% in the fetal zone. Incubations with secretagogues or antioxidants (10 nmol/L ACTH, 10 nmol/L angiotensin-II, 21 mmol/L potassium, 100 mmol/L dimethylsulfoxide, 5 mumol/L metyrapone, or 100 mumol/L butylated hydroxyanisole) did not change the pattern or extent of precursor metabolism. No aldosterone, 18-hydroxycorticosterone, or 18-hydroxydeoxycorticosterone was detected in baseline or stimulated incubations of human fetal tissue. In contrast, adult human zona glomerulosa metabolized corticosterone to aldosterone, 18-hydroxycorticosterone, and 11-dehydrocorticosterone under similar conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Estrogen receptors (ERs) regulate transcription by interacting with regulatory elements in target genes. However, known ER regulatory elements cannot explain the expression profiles of genes activated by estradiol (E2) and selective estrogen receptor modulators (SERMs). We previously showed that the killer cell lectin-like receptor (NKG2E) gene is regulated by E2, tamoxifen, and raloxifene. Here we used the NKG2E gene as a model to investigate the mechanism whereby target genes are regulated by E2 and SERMs with ERα. The ER regulatory element in the NKG2E promoter was mapped to the −1825 and −1686 region. Full activation of the NKG2E promoter required the collaboration between a transcription factor cluster containing c-jun, heat-shock factor 2, and CCAAT/enhancer-binding protein β and a unique variant estrogen response element (ERE) that has only a two nucleotide spacer between half sites. The cluster elements and the variant ERE were inactive on their own, but the regulation by E2 and SERMs was restored when the c-jun, heat-shock factor-2, and CCAAT/enhancer-binding protein β cluster was placed upstream of the variant ERE. The activation of the NKG2E gene by E2 and selective ER modulators was associated with the recruitment of the p160 coactivators glucocorticoid receptor-interacting protein 1 and amplified in breast cancer 1 but not steroid receptor coactivator 1. These studies identified one of the most complex ER regulatory units thus far reported and demonstrate that a cluster of flanking transcription factors collaborate with ER to induce a functional ERE in the NKG2E promoter.

Context: In the human fetal adrenal gland (HFA), the inner fetal zone (FZ) secretes dehydroepiandrosterone sulfate. The function of the outer definitive zone (DZ) is less clear; however, the DZ phenotype is that of a reservoir of progenitor cells, many of which are mitotically active. Midkine (MK) is a heparin-binding growth factor with various bioactivities. Objective: The objective of this study was to investigate expression, proliferative effects, and ACTH regulation of MK in the HFA. Design and Setting: RNA, cryosections, and primary cell cultures from HFAs (14–24 wk) and adult adrenal RNA were used. Main Outcome Measures: The main outcome measures were MK mRNA levels (measured by quantitative real-time RT-PCR); MK localization (measured by immunostaining); MK proliferative effects and mechanism (measured by proliferation assays, flow cytometry, pharmacological interventions); and ACTH regulation (measured by quantitative real-time RT-PCR). Results: HFA MK mRNA levels were 4-fold higher than in adult adrenals (P < 0.05) and were comparable to levels in fetal and adult brains (positive controls). MK immunoreactivity was abundant throughout the HFA. Exogenous MK caused proliferation of isolated DZ cells but not FZ cells (72 h, P < 0.05). In contrast, basic fibroblast growth factor induced proliferation of cells from both zones. Pharmacological interventions indicated that MK-induced DZ cell proliferation may be mediated by phosphatidylinositol 3-kinase, MAPK kinase, and Src family kinases. ACTH (1 nm) increased MK mRNA by 3.5-fold (48 h, P < 0.01) in isolated FZ cells. Conclusions: MK likely plays a key role in HFA development. MK’s selective in vitro mitotic effects on DZ cells may provide insights into the mechanism underlying the distinct in vivo differences in mitotic activity between the DZ and FZ.

ACTH is the key tropic hormone for the human fetal adrenal (HFA). Because vascular development must be coordinated with organ growth, ACTH may regulate local angiogenic factors, thereby influencing HFA angiogenesis. We previously demonstrated that ACTH up-regulates vascular endothelial growth factor in HFA cortical cells. A newer angiogenic factor family, the angiopoietins (Angs), also plays critical roles. Ang1 stabilizes, whereas Ang2 destabilizes vessels, increasing responsiveness to angiogenic stimuli.The objective of this study was to investigate expression and ACTH regulation of Angs and their receptor Tie2 in the HFA.Studies were conducted involving RNA, frozen sections, and primary cell cultures from HFAs (14-24 wk) and human adult adrenal RNA.Angs and Tie2 mRNA levels were determined by real-time quantitative RT-PCR, Ang2 and Tie2 were localized by immunostaining, and ACTH regulation of Angs was investigated by real-time quantitative RT-PCR, Western blot, and ELISA.Mean HFA Ang2 to Ang1 mRNA ratio was 6.3-fold higher than adult adrenals (P0.001). Ang2 was localized predominantly in the HFA periphery, whereas Tie2 demonstrated endothelial localization. In isolated HFA cortical cells, ACTH up-regulated Ang mRNA levels in a time- and dose-dependent manner, with the balance favoring Ang2. Ang2 protein levels were elevated in ACTH-stimulated HFA cortical cells and conditioned medium. 8-Bromoadenosine cAMP and forskolin mimicked ACTH effects on the Angs.Higher HFA Ang2 to Ang1 ratios may reflect greater vascular remodeling than in the adult. Angs, particularly Ang2, in concert with vascular endothelial growth factor, may mediate ACTH tropic action, ensuring coordination of HFA growth, steroidogenesis, and angiogenesis.

Elucidating the genetic and molecular mechanisms that control the development and remodeling of capillary blood vessels is critical to an understanding of ovarian biology. Neovascularization, the formation of new blood vessels, can be considered as two distinct biologic processes: vasculogenesis and angiogenesis. Vasculogenesis refers to the de novo formation of blood vessels, observed primarily during embryogenesis, whereas angiogenesis refers to the process by which new capillaries develop from preexisting vessels. Angiogenesis occurs in physiologic and pathologic conditions, and this dichotomy is particularly evident in the human ovary. The vasculogenesis/angiogenesis process requires tight orchestration of vascular endothelial cell-specific growth factors, controlled by endocrine, paracrine, and autocrine regulation, as well as by a variety of other growth factors, cytokines, and a number of environmental influences such as hypoxia. Therefore the lack of appropriate integration of one or more of these factors may adversely affect ovarian physiology. In the normal ovary, angiogenesis likely plays an important role in folliculogenesis, ovulation, and corpus luteum function. Pathologic conditions involving the ovary also involve angiogenesis, including ovarian hyperstimulation syndrome, corpus luteum insufficiency, and benign and malignant neoplasms. This chapter focuses on physiological and pathological mechanisms of ovarian angiogenesis.

The cortex of the human midgestation adrenals comprises a thin layer of cells, the definitive zone (DZ) that surrounds the larger, inner fetal zone (FZ). CD56 expression was observed by immunohistochemistry on DZ cells and isolated groups of cells within the FZ. CD56 mRNA expression also was detected among DZ cells but not selected sections of FZ cells isolated by laser capture microdissection. Flow cytometric analysis of dispersed adrenal cells indicated CD56 expression on a subset of adrenal cells lacking expression of hematopoietic (CD45(+) and CD235a(+)) and endothelial (CD31(+)) cell markers. The CD56(+)CD31(-)CD45(-)CD235a(-) cells were isolated by discontinuous-gradient centrifugation and fluorescence-activated cell sorting. The purified cells were enriched for DZ cells based on expression of mRNA for metallopanstimulin-1, nephroblastoma overexpressed gene, and 3-beta-hydroxysteroid dehydrogenase. P450c17 mRNA expression also was detected among a subset of CD56(+) cells consistent with expression of low levels of this protein in some DZ cells. The presence of a subpopulation of chromaffin cells among the CD56(+) population also was shown by the expression of chromogranin A mRNA. These findings indicate that CD56 expression can be used to isolate DZ and chromaffin cells to further study their functional and developmental properties.

Gonadotropin-releasing hormone agonists and antagonists have initial divergent effects on the pituitary secretion of intact biologically active gonadotropins and long-term divergent effects on the secretion of free alpha-subunit. The antagonists appear to function as true competitive inhibitors, blocking the stimulatory effects of endogenous GnRH without evoking any known postreceptor activity. The agonists, in contrast, initially stimulate pituitary secretion and then incompletely desensitize the gonadotrope, resulting in suppression of intact gonadotropin, but not free alpha-subunit, secretion. The mechanisms by which GnRH-a produce this incomplete gonadotrope desensitization and facilitate limited postreceptor activity remain to be elucidated.

Lysophosphatidic acid (LPA), the simplest of all phospholipids, exhibits pleiomorphic functions in multiple cell lineages. The effects of LPA appear to be mediated by binding of LPA to specific members of the endothelial differentiation gene (Edg) family of G protein-coupled receptors (GPCR). Edg 2, Edg4, and Edg7 are high affmity receptors for LPA, and Edgl may be a low affinity receptor for LPA. PSP24 has been shown to be responsive to LPA in Xenopus oocytes, however, its role in mammalian cells is unclear. The specific biochemical events initiated by the different Edg receptors, as well as the biological outcomes of activation of the individual receptors, are only beginning to be determined. LPA levels are consistently elevated in the plasma and ascites of ovarian cancer patients, but not in most other epithelial tumors, with the exception of cervix and endometrium, suggesting that LPA may be of particular importance in the pathophysiology of ovarian cancer. In support of this concept, ovarian cancer cells constitutively and inducibly produce high levels of LPA and demonstrate markedly different responses to LPA than normal ovarian surface epithelium. Edg4 and Edg7 levels are consistently increased in malignant ovarian epithelial cells contributing to the aberrant response of ovarian cancer cells to LPA. Edg2 may represent a negative regulatory LPA receptor inducing apoptosis in ovarian cancer cells. Thus, increased levels of LPA, altered receptor expression and altered responses to LPA may contribute to the initiation, progression or outcome of ovarian cancer. Over 40% of known drugs target GPCR, making LPA receptors attractive targets for molecular therapeutics. Indeed, using the structure-function relationship of LPA in model systems, we have identified selective Edg2 antagonists, as well as Edg4 and Edg7 agonists. These lead compounds are being assessed in preclinical model systems. Understanding the mechanisms regulating LPA production, metabolism and function could lead to improved methods for early detection and to new targets for therapy in ovarian cancer.

Breast and ovarian cancers exhibit similar epidemiologic, genotypic, and phenotypic characteristics. Phosphatidylinositol 3-kinase (P13K) and the PTEN tumor suppressor gene product phosphorylate and dephosphorylate the same 3′ site in the inositol ring of membrane phosphatidylinositols. Germ-line mutations in the PTEN tumor suppressor gene are causative of Cowden's breast cancer predisposition syndrome, and PTEN is frequently mutated in sporadic breast cancers. In contrast, amplification of multiple components of the P13K pathway is a hallmark of serous epithelial ovarian cancers. The resultant activation of the P13K pathway in both breast and ovarian cancers contributes to cell-cycle progression, decreased apoptosis, and increased metastatic capabilities. Strikingly, both ovarian and breast cancer cells are selectively sensitive to pharmacologic and genetic manipulation of the P13K pathway, making molecular therapeutics targeting this pathway particularly attractive approaches for these cancers.

Hormones produced by the fetal adrenal regulate fetal growth, steroidogenic activity, and intrauterine homeostasis, which are essential for the maintenance of pregnancy and the preparation of the fetus for extrauterine life. There is a functional interaction between CRH and the fetal adrenal, as CRH increases dehydroepiandrosterone sulfate production in cultured fetal adrenal cells. Moreover, in a rodent model administration of orexin A induced corticosterone production. To examine this relationship in more detail we measured the expression of the different subtypes of CRH and orexin receptors and their specific coupling to G protein alpha-subunits upon activation with CRH and orexin A, respectively. Using RT-PCR and fluorescent in situ hybridization analysis, we demonstrated the presence of CRH receptors 1alpha and 2alpha, and orexin type 2 receptor mRNA. None of the other CRH receptor variants or orexin type 1 receptor were detected. Immunofluorescent analysis and Western blotting confirmed the protein expression of both receptors, which also bind fluo-CRH and fluo-orexin with high affinity. Immunoblotting analysis confirmed the expression of prepro-orexin and orexin A in fetal adrenals. Using photoaffinity labeling, we determined which G proteins are coupled to the CRH and orexin receptors in fetal adrenals when challenged with CRH or orexin. Treatment of fetal adrenal membranes with CRH (100 nM) increased the labeling of G(o) and, to a lesser extent, G(s), but not G(i) and G(q), whereas treatment with orexin A (100 nM) increased the labeling of G(s) and G(i), but not G(o) and G(q). These findings provide new insights into the components of the signal transduction machinery in human fetal adrenals and demonstrate for the first time the presence of functional orexin receptors outside of the CNS in humans.

Lysophosphatidic acid (LPA) stimulates ovarian tumor growth at concentrations present in ascitic fluid. Vascular endothelial growth factor (VEGF) stimulates angiogenesis and plays a pivotal role in the formation of ovarian cancer-associated ascites. We examined whether LPA promotes ovarian tumor growth by increasing angiogenesis via VEGF.VEGF expression was examined in a simian virus 40 T-antigen-immortalized ovarian surface epithelial cell line (IOSE-29) and in ovarian cancer cell lines (OVCAR-3, SKOV-3, and CAOV-3) treated with LPA. VEGF promoter activity was measured in OVCAR-3 cells after transfection or cotransfection with c-Fos and c-Jun, components of AP1 transcription factor, potential binding sites for which are present in the VEGF promoter. The expression of the LPA receptors Edg2 and Edg4 was also assessed. All statistical tests were two-sided.LPA treatment increased steady-state VEGF messenger RNA (mRNA) levels in OVCAR-3 cells in a time- and dose-dependent fashion and stimulated VEGF promoter activity without prolonging mRNA half-life in these cells, but LPA had little effect on IOSE-29 cells. Forced overexpression of c-Jun and c-Fos in OVCAR-3 cells stimulated VEGF promoter activity fourfold. LPA also elevated VEGF protein levels by 1.5-fold in SKOV-3 cells (P =.0148), 1.9-fold in CAOV-3 cells (P.001), and threefold in OVCAR-3 cells (P.0001). Both Edg2 and Edg4 were detected in ovarian cancer cells; however, only Edg2 was present in normal ovarian surface epithelial cells and IOSE-29 cells.LPA stimulates ovarian tumor growth, at least in part, via induction of VEGF expression through transcriptional activation. However, this LPA response is not evident in normal ovarian surface epithelial cells. Our data suggest that Edg4, but not Edg2, plays a role in LPA stimulation of ovarian tumor growth.

The specificity of cellular effects of lysolipid phosphate (LLP) growth factors is determined by binding to endothelial differentiation gene-encoded G protein-coupled receptors (EDG Rs), which transduce diverse proliferative and effector signals. The primary determinants of cellular responses to LLPs are the generative and biodegradative events, which establish steady-state concentrations of each LLP at cell surfaces, and the relative frequency of expression of each EDG R. There are major differences among types of cells in the net effective generation of the LLPs, lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P), and in their profile of expression of EDG Rs. The less well characterized secondary determinants of cellular specificity of LLPs are high-affinity binding proteins with carrier and cell-presentation functions, cell-selective regulators of expression of EDG Rs, and cellular factors that govern coupling of EDG Rs to G protein transductional pathways. The roles of components of the LLP-EDG R system in normal physiology and disease processes will be definitively elucidated only after development of animal models with biologically meaningful alterations in genes encoding EDG Rs and the discovery of potent and selective pharmacological probes.

Levels of lysophosphatidic acid (LPA) and lysophosphatidylcholine (LPC) are elevated in the plasma and ascites of ovarian cancer patients, but not in most other tumor types. LPA increases cell proliferation, cell survival, resistance to cisplatin, cell shrinkage, and production of vascular endothelial growth factor, urokinase plasminogen activator, and LPA itself in ovarian cancer cells, but not in normal ovarian surface epithelial cells. PSP24 and members of the endothelial differentiation gene (EDG) family (EDG1, EDG2, EDG4, and EDG7) of G protein-coupled receptors mediate LPA signaling. Ovarian cancer cell lines do not express EDG1 mRNA, have variable EDG2 mRNA and protein levels, and frequently exhibit levels of EDG4 mRNA and protein, suggesting that EDG4 may contribute to the deleterious effects of LPA in ovarian cancer. In contrast, activation of the EDG2 LPA receptor on ovarian cancer cells may lead to apoptosis and counter the effects of other LPA receptors. Thus, the development of agonists and antagonists for the appropriate spectrum of LPA receptors may alter proliferation, apoptosis, or response to therapy of ovarian cancer cells. Indeed, over 60% of all current drugs target the G protein-coupled family of receptors, making the LPA receptor family a "drugable" target. LPC, although not as thoroughly studied, increases cellular proliferation and mediates multiple other functions through unique signaling pathways.

CRH directly stimulates dehydroepiandrosterone sulfate (DHEAS) production in human fetal adrenal cells. In the human fetal and adult pituitary, CRH acts via protein kinase A (PKA). We determined the CRH signal transduction pathway in fetal adrenal cells, i.e. whether CRH modulates human fetal adrenal steroidogenesis via PKA and/or protein kinase C (PKC).In primary cultures, CRH increased inositol trisphosphate. After CRH treatment, inositol tris-, bis-, and monophosphates increased within 1 min, reaching maximal levels at 5 min. In contrast, PGF2α, known to act via PKC, induced a sustained response for up to 20 min. The response to CRH was dose dependent, maximal at 1μ mol/L at both 1 and 5 min. CRH increased DHEAS production, with a much lesser effect on cortisol. CRH did not stimulate inositol phospholipid in adult adrenal glands, suggesting that this pathway is unique to the fetal adrenal. CRH increased messenger ribonucleic acid encoding 17α-hydroxylase/17,20 lyase (P450c17), but not 3β-hydroxysteroid dehydrogenase/Δ4–5 isomerase. However, 3βHSD expression was stimulated by ACTH. PKC, but not PKA, inhibitors blocked CRH-stimulated P450c17 induction, whereas PKA inhibitors blocked ACTH-stimulated cortisol. Thus, CRH is coupled to the phospholipase C-inositol phosphate second messenger system and preferentially induces the expression of P450c17 and DHEAS, suggesting a unique role of CRH regulating human fetal adrenal function via PKC.