Estrogens downregulate urocortin 2 expression in rat uterus

Corticotropin Releasing Factor Receptors in breast cancer: Expression and activity in hormone-dependent growth in vitro

Corticotropin Releasing Factor (CRF) neuropeptides coordinate the stress response via two distinct membrane receptors (CRF-Rs). We have previously shown expression of both CRF-Rs in human breast cancer tissues. In the present study, we examined in vitro using the MCF-7 cell line model, the regulation of CRF-Rs expression and their signaling in hormone-dependent breast cancer growth. Our findings show that similarly to breast cancer biopsies, the predominant receptor type expressed in the cell line is CRF-R2α. The transcription of CRF-R1 and CRF-R2 is up and down-regulated respectively by exposure to estradiol (E2); however this effect seems not to be exerted at the level of promoter gene methylation, although in human breast cancer specimens, CRF-R1 methylation was found to be positively associated with the presence of steroid hormone receptors. Finally, we showed that specific activation of CRF-R2 increased the migration of MCF-7 cells and potentiated an estrogen-inducing effect. Our data support an involvement of CRF-R signaling in breast cancer pathophysiology via a regulatory steroid-hormone interplay.

Urocortins in the mammalian endocrine system

Urocortins (Ucns), peptides belonging to the corticotropin-releasing hormone (CRH) family, are classified into Ucn1, Ucn2, and Ucn3. They are involved in regulating several body functions by binding to two G protein-coupled receptors: receptor type 1 (CRHR1) and type 2 (CRHR2). In this review, we provide a historical overview of research on Ucns and their receptors in the mammalian endocrine system. Although the literature on the topic is limited, we focused our attention particularly on the main role of Ucns and their receptors in regulating the hypothalamic–pituitary–adrenal and thyroid axes, reproductive organs, pancreas, gastrointestinal tract, and other tissues characterized by “diffuse” endocrine cells in mammals. The prominent function of these peptides in health conditions led us to also hypothesize an action of Ucn agonists/antagonists in stress and in various diseases with its critical consequences on behavior and physiology. The potential role of the urocortinergic system is an intriguing topic that deserves further in-depth investigations to develop novel strategies for preventing stress-related conditions and treating endocrine diseases.

Glucocorticoid withdrawal affects stress-induced changes of urocortin 2 gene expression in rat adrenal medulla and brain

Corticotropin-releasing factor is well known activator of the hypothalamic-pituitary-adrenocortical axis, that represents crucial system participating on stress response of the organism. Urocortins are members of the corticotropin-releasing factor family of peptides with proposed effects on neuroendocrine and behavioral stress response mechanisms. Urocortin 2, one of three known urocortins, is present in central and peripheral stress response system and its expression can be augmented by glucocorticoids. In the present study we have examined how glucocorticoid withdrawal affects urocortin 2 gene expression after acute immobilization in the adrenal medulla and selected brain areas in rats. We used pharmacological adrenalectomy to block synthesis of corticosterone. Our results show that the immobilization-induced rise in urocortin 2 mRNA levels in rat adrenal medulla was not inhibited by glucocorticoid withdrawal. On the other hand, observed changes in the brain indicate that the effect of stress and pharmacological adrenalectomy on urocortin 2 gene expression is site-specific. While in the paraventricular nucleus and locus coeruleus the immobilization induced rise of urocortin 2 was not inhibited by pharmacological adrenalectomy in the arcuate nucleus and central amygdala it was. Moreover, we have seen a significant depletion of urocortin 2 plasma levels after immobilization. The immobilization induced rise of urocortin 2 gene expression in rat adrenal medulla and brain areas regulating stress response pathways and preservation of its induction after adrenalectomy suggests a role of urocortin 2 in the neuroendocrine stress response of an organism. This article is protected by copyright. All rights reserved.

Urocortin suppresses endometrial cancer cell migration via CRFR2 and its system components are differentially modulated by estrogen

Urocortin (UCN1) peptide shares structural and functional homology with corticotropin‐releasing factor (CRF). UCN1 is significantly reduced in endometrial adenocarcinoma compared to healthy controls. However, there are no data which evaluate the effects of UCN1 in the endometrium, or how it is modulated. We used proliferation and transwell assays to determine the effect of UCN1 on the proliferation and migration of Ishikawa and HEC1A cells. We also determined the expression levels of UCN1 and its receptors produced by estrogen receptor agonists, and the effect of UCN1 on estrogen receptor expression, using quantitative polymerase chain reaction. UCN1 suppressed migration of endometrial cancer cells in vitro. This effect appears to be specific to CRF receptor 2 (CRFR2), as selective antagonism of CRFR2 but not CRFR1 completely eliminated suppression of migration. Activation of ERA reduced UCN1 expression, but only had a small effect on the expression of CRFR1. However, expression of CRFR2 was more notably reduced at both the mRNA and protein levels by activation of ERB. UCN1 in turn reduced both ERA and ERB expression, as assessed by real‐time quantitative PCR. We demonstrate that UCN1 significantly suppresses the migration of endometrial cancer cells but has no effect on their proliferation. Thus, loss of UCN1 in endometrial cancer may promote invasion and metastatic spread. There is a complex relationship between the UCN1 system and estrogen receptors, which may provide insights into endometrial carcinogenesis, a disease known to be driven by estrogen excess.

Sex and estrogen affect the distribution of urocortin-1 immunoreactivity in brainstem autonomic nuclei of the rat

Urocortin-1 (UCN-1), a neuropeptide closely related to the hypothalamic hormone corticotropin-releasing factor, has been associated with stress, feeding behaviors, cardiovascular control, and to exhibit functional gender differences. This study was done to investigate whether estrogen (E; 17β-estradiol) treatment (9 weeks) altered UCN-1 immunoreactivity in brainstem autonomic nuclei in female Wistar rats. Experiments were done in age matched adult males (controls), females (intact), and ovariectomized (OVX) only and OVX+E (30pg/ml plasma) treated females. All animals received intracerebroventricular injections of colchicine and were then perfused transcardially with Zamboni's fixative. Coronal brainstem sections (40μm) were cut and processed immunohistochemically for UCN-1. In males, moderate UCN-1 fiber labeling was found in the nucleus of the solitary tract (NTS) and throughout the rostral ventral lateral medulla (RVLM). Additionally, a few UCN-1 immunoreactive neurons were observed in hypoglossal nucleus (XII), facial nucleus (FN) and nucleus ambiguus (Amb). In intact females and OVX+E females, fewer UCN-1 labeled fibers were found within NTS compared to males. In contrast, the RVLM was more densely innervated in the female cases. Furthermore, in both intact and OVX+E females UCN-1 labeled neurons were found not only within Amb, FN and XII, but also within NTS, RVLM and nucleus raphé pallidus (RP). In OVX only animals, moderate to dense UCN-1 fiber labeling was observed in the NTS complex and throughout RVLM compared to males and the other female groups. However, in contrast to all other groups, UCN-1 labeled neurons were found in greater number within Amb, FN, NTS, dorsal motor nucleus of the vagus, XII, RVLM, magnocellular reticular nucleus and RP. These data not only suggest that sex differences exist in the distribution of UCN-1 within brainstem autonomic areas, but that circulating level of E may play an important role with regards to the function of these UCN-1 neurons during stress responses.