Corticotropin-releasing factor (CRF) receptor type 2 in the human stomach: protective biological role by inhibition of apoptosis

Acute iv CRH administration significantly increases serum active ghrelin in postmenopausal PCOS women compared to postmenopausal controls

PURPOSE

In women with Polycystic Ovarian Syndrome (PCOS), an increased risk of disordered eating has been described. There is growing interest regarding a possible interconnection between psychological states and increased appetite in women with PCOS. Acute stress is characterized by increased Corticotropin Releasing Hormone (CRH) secretion. The aim was to estimate the ghrelin concentrations during CRH test.

METHODS

Twenty postmenopausal women with PCOS and twenty age- and BMI- matched postmenopausal control women were recruited at Aretaieion University Hospital. In the morning (9 am) all subjects had anthropometric measurements (weight, height, waist circumference) and a fasting sample for hormonal measurements. An intravenous (iv) CRH stimulation test conducted over 1 min. Serum active ghrelin levels were measured at 0, 15, 30, 60, 90, 120 min after iv CRH administration.

RESULTS

The postmenopausal PCOS group had a higher waist circumference compared to postmenopausal controls. Active ghrelin concentrations increased significantly from 0 to 15 min, to 30 min, to 60 min, to 90 min and then decreased to 120 min. However, within the postmenopausal control group there were no significant changes in serum active ghrelin levels. Serum active ghrelin concentrations were significantly greater in the postmenopausal control group at 0, 15 and 120 min compared to the postmenopausal PCOS group. At 90 min active ghrelin concentrations were significantly greater in the postmenopausal PCOS group. Delta Area Under the Curve of active ghrelin (ΔAUCghr) was significantly greater in the postmenopausal PCOS group compared to controls.

CONCLUSIONS

In postmenopausal PCOS, but not in postmenopausal controls, iv CRH administration induces increased serum active ghrelin secretion, suggesting a possible anti-stress adaptive mechanism. An increase in serum active ghrelin may induce hunger as a side-effect of this presumed adaptive mechanism.

Urocortin stimulates ERK1/2 phosphorylation and proliferation but reduces ATP production of MCF7 breast cancer cells

Urocortins are members of the stress-related corticotropin-releasing factor family. Small amounts of them are present in the circulation and they are produced locally in various tissues of higher vertebrates. Aside from regulating circulation, or food uptake they also influence, via auto- and paracrine mechanisms, cell proliferation. In the present study we investigated in MCF7 human breast cancer cells the effect of urocortin onto mitogenic signaling via ERK1/2. Our results revealed that already 10 nM urocortin could stimulate the phosphorylation of these kinases and cell proliferation of MCF7 cells while ATP production was reduced when kept in the presence of the peptide up to two days. We examined the expression and contribution of the specific receptors of urocortin to the activation of ERK1/2 and to cell proliferation, the intracellular distribution of phosphorylated ERK1/2, and the involvement of additional proteins like PKA, PKB/Akt, MEK, p53, Rb and E2F-1 behind the observed phenomena.

Therapeutic efficiency of adipose-derived mesenchymal stem cells in healing of experimentally induced gastric ulcers in rats

Gastric (peptic) ulcer is a major gastrointestinal disorder with high morbidity and mortality. While several drugs have been used to treat gastric ulcers, such as proton pump inhibitor-based triple therapy for Helicobacter pylori eradication, but hey result in adverse side effects. Therefore, development of new alternative therapies is desirable. Many recent studies have shown that mesenchymal stem cells (MSCs) might have an enhancing effect on the ulcerated gastric mucosa. The aim of this study is to evaluate the efficacy of MSCs in the treatment of indomethacin-induced gastric ulcer, and to compare it with the normal ulcer autohealing. This work was performed on 36 adult male albino rats, divided into four groups: Group I (control group), Group II (ulcer group), Group III (autohealing group), and Group IV (stem cells-treated group). The histological changes of gastric mucosa were examined in sections stained with H&E using light microscope for expression of vascular endothelial growth factors (VEGF) and proliferating cell nuclear antigen (PCNA) in immunohistochemical stained sections using image analyzer. The results from MSCs-treated group revealed restoration of the normal architecture of the gastric mucosa with comparison to the autohealing group which showed excessive granulation tissue and heavy cellular infiltration with disorganized architecture of the fundic mucosa. Immunohistochemical examination showed strong expression of both VEGF and PCNA in the MSCs-treated group. So it was concluded that MSCs accelerate gastric ulcer healing when injected intraperitoneally, compared to autohealing process which showed delayed healing.

Methylation Status of Corticotropin-Releasing Factor (CRF) Receptor Genes in Colorectal Cancer

The corticotropin-releasing factor (CRF) system has been strongly associated with gastrointestinal pathophysiology, including colorectal cancer (CRC). We previously showed that altered expression of CRF receptors (CRFRs) in the colon critically affects CRC progression and aggressiveness through regulation of colonic inflammation. Here, we aimed to assess the potential of CRFR methylation levels as putative biomarkers in CRC. In silico methylation analysis of CRF receptor 1 (CRFR1) and CRF receptor 2 (CRFR2) was performed using methylome data derived by CRC and Crohn's disease (CD) tissues and CRC-derived circulating cell-free DNAs (ccfDNAs). In total, 32 and 33 differentially methylated sites of CpGs (DMCs) emerged in CRFR1 and CRFR2, respectively, between healthy and diseased tissues. The methylation patterns were verified in patient-derived ccfDNA samples by qMSP and associated with clinicopathological characteristics. An automated machine learning (AutoML) technology was applied to ccfDNA samples for classification analysis. In silico analysis revealed increased methylation of both CRFRs in CRC tissue and ccfDNA-derived datasets. CRFR1 hypermethylation was also noticed in gene body DMCs of CD patients. CRFR1 hypermethylation was further validated in CRC adjuvant-derived ccfDNA samples, whereas CRFR1 hypomethylation, observed in metastasis-derived ccfDNAs, was correlated to disease aggressiveness and adverse prognostic characteristics. AutoML analysis based on CRFRs methylation status revealed a three-feature high-performing biosignature for CRC diagnosis with an estimated AUC of 0.929. Monitoring of CRFRs methylation-based signature in CRC tissues and ccfDNAs may be of high diagnostic and prognostic significance in CRC.

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.

Mucosa repair mechanisms of Tong-Xie-Yao-Fang mediated by CRH-R2 in murine, dextran sulfate sodium-induced colitis

AIM

To explore the significance of corticotropin-releasing hormone (CRH)-receptor (R)2 in mucosal healing of dextran sulfate sodium (DSS)-induced colitis and the effect of Tong-Xie-Yao-Fang (TXYF) on CRH-R2 expression and regulation.

METHODS

Ulcerative colitis was induced in mice by administration of 3% (w/v) DSS for 7 d. Once the model was established, mice were administered urocortin-2 (30 μg/kg), a peptide which binds exclusively to CRH-R2, or various doses of aqueous TXYF extracts (2.8-11.2 g/kg), a CRH-R2 antagonist Astressin (Ast)2B (20 μg/kg), Ast2B + Ucn2, or Ast2B with various doses of aqueous TXYF extracts for 9 d. Colonic mucosal permeability was then evaluated by measuring the fluorescence intensity in serum. The colitis disease activity index (DAI), histology, body weight loss and colon length were assessed to evaluate the condition of colitis. Terminal deoxynucleotidyl transferase dUTP nick-end labeling was used to detect apoptosis of the intestinal epithelial cells. The expression level of Ki-67 represented the proliferation of colonic epithelial cells and was detected by immunohistochemistry. The expression levels of inflammation cytokines IL-6, TNF-α and CXCL-1 were examined in colon tissues using real-time PCR and ELISA kits.

RESULTS

Compared with the DSS group, mice treated with the CRH-R2 antagonist Ast2B showed greater loss of body weight, shorter colon lengths (4.90 ± 0.32 vs 6.21 ± 0.34 cm, P < 0.05), and higher DAI (3.61 ± 0.53 vs 2.42 ± 0.32, P < 0.05) and histological scores (11.50 ± 1.05 vs 8.33 ± 1.03, P < 0.05). Additionally, the Ast2B group showed increased intestinal permeability (2.76 ± 0.11 μg/mL vs 1.47 ± 0.11 μg/mL, P < 0.001), improved secretion of inflammatory cytokines in colon tissue, and reduced colonic epithelial cell proliferation (4.97 ± 4.25 vs 22.51 ± 8.22, P < 0.05). Increased apoptosis (1422.39 ± 90.71 vs 983.01 ± 98.17, P < 0.001) was also demonstrated. The Ucn2 group demonstrated lower DAI (0.87 ± 0.55 vs 2.42 ± 0.32, P < 0.001) and histological scores (4.33 ± 1.50 vs 8.33 ± 1.03, P < 0.05). Diminished weight loss, longer colon length (9.58 ± 0.62 vs 6.21 ± 0.34 cm, P < 0.001), reduced intestinal permeability (0.75 ± 0.07 vs 1.47 ± 0.11 μg/mL, P < 0.001), inhibited secretion of inflammatory cytokines in colon tissue and increased colonic epithelial cell proliferation (90.04 ± 15.50 vs 22.51 ± 8.22, P < 0.01) were all observed. Reduced apoptosis (149.55 ± 21.68 vs 983.01 ± 98.17, P < 0.05) was also observed. However, significant statistical differences in the results of the Ast2B group and Ast2B + Ucn2 group were observed. TXYF was also found to ameliorate symptoms of DSS-induced colitis in mice and to promote mucosal repair like Ucn2. There were significant differences between the Ast2B + TXYF groups and the TXYF groups.

CONCLUSION

CRH-R2 activates the intestinal mucosal antiinflammatory response by regulating migration, proliferation and apoptosis of intestinal epithelial cells in colitis-induced mice, and plays an important antiinflammatory role. TXYF promotes mucosal repair in colitis mice by regulating CRH-R2.

Pharmacotherapy in smoking cessation: Corticotropin Releasing Factor receptors as emerging intervention targets

Smoking represents perhaps the single most important health risk factor and a global contributor to mortality that can unquestionably be prevented. Smoking is responsible for many diseases, including various types of cancer, chronic obstructive pulmonary disease, coronary heart disease, peripheral vascular disease and peptic ulcer, while it adversely affects fetal formation and development. Since smoking habit duration is a critical factor for mortality, the goal of treatment should be its timely cessation and relapse prevention. Drug intervention therapy is an important ally in smoking cessation. Significant positive steps have been achieved in the last few years in the development of supportive compounds. In the present review, we analyze reports studying the role of Corticotropin Releasing Factor (CRF), the principle neuroendocrine mediator of the stress response and its two receptors (CRF1 and CRF2) in the withdrawal phase as well as in the abstinence from nicotine use. Although still in pre-clinical evaluation, therapeutic implications of these data were investigated in order to highlight potential pharmaceutical interventions.

Urocortin attenuates TGFβ1-induced Snail1 and slug expressions: inhibitory role of Smad7 in Smad2/3 signaling in breast cancer cells

Corticortropin-releasing hormone (CRH) family are multifunctional endocrine-factors that regulate proliferation, apoptosis, and migration of various types of cancer cells. Deregulation of the transforming growth factor β1(TGFβ1) signal transduction promotes aggressive metastatic properties in late-stage breast cancers. We previously have demonstrated in breast cancer cell line that CRH suppressed TGFβ1-induced Epithelial-Mesenchymal Transition (EMT) via induction of E-cadherin. Our present data in MCF-7 and MDA-MB-231 cells showed that Urocortin (Ucn, a member of CRH family) inhibited TGFβ1 signaling by reducing Smad2/3 activation and subsequent nuclear translocation through increasing Smad7 expression, leading to downregulation of Snail1 and Slug, the two EMT promoters. We further found that Antalarmin (CRH receptor type 1, CRHR1 antagonist) and Antisauvagine-30 (CRH receptor type2, CRHR2 antagonist) abrogated the effects of Ucn on TGFβ1 signaling, implying that both active CRHR1 and CRHR2 participate in Ucn-repressed TGFβ1 signaling. Our findings, for the fist time, identify Ucn as a potential mediator that inhibits oncogenic signaling by TGFβ1 and suggest that activating CRHR1 and R2 may prove effective in diminishing breast cancer progression stimulated by TGFβ1.

Corticotropin-releasing factor (CRF) system localization in human fetal heart

OBJECTIVE

The corticotropin-releasing factor (CRF) family consists of the neuropeptides CRF, Ucn I, II and III and the binding sites CRFR1, CRFR2 and CRF-BP. It regulates stress response and the homeostasis of an organism. In this study, we examined the presence of the CRF system in the human hearts of normal and pathological fetuses.

DESIGN

Heart tissues from 40 archival human fetuses were divided into Group A (without pathology, 'normal'), Group B (with chromosomal abnormalities) and Group C (with congenital disorders). Immunohistochemistry was used to localize the CRF system. Results correlated to gestational trimester and pathology.

RESULTS

Immunoreactivity for all antigens was found in cardiac myocytes of all groups, in almost all samples, except Ucn III which was present in almost half of the fetuses of Groups B and C and was not detected at all in Group A. Ucn III was more often present during the earlier stage of development (<21 weeks) and in fetuses with congenital disorders. In a fetus diagnosed with heart pathology, all but Ucn III antigens were also present.

CONCLUSIONS

We localized a complete CRF system in the human fetal heart and correlated the presence of Ucn III to development and pathology. More studies are needed to verify and clarify the exact role of the CRF system in the human fetal heart.

Corticotropin-Releasing Hormone Receptor 2 Signaling Promotes Mucosal Repair Responses after Colitis

The corticotropin-releasing hormone family mediates functional responses in many organs, including the intestine. Activation of corticotropin-releasing hormone receptor 2 (CRHR2) in the colonic mucosa promotes inflammation during acute colitis but inhibits inflammation during chronic colitis. We hypothesized that specific modulation of CRHR2 signaling in the colonic mucosa can promote restoration of the epithelium through stimulation of cell proliferative, migratory, and wound healing responses. Mucosal repair was assessed after dextran sodium sulfate (DSS)-induced colitis in mice receiving intracolonic injections of a CRHR2 antagonist or vehicle and in Crhr2(-/-) mice. Histologic damage, cytokine expression, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling, and Ki-67 immunoreactivity were evaluated. Cell viability, proliferation, and migration were compared between parental and CRHR2-overexpressing colonic epithelial cells. Protein lysates were processed for phosphoprotein assays and a wound healing assay performed in vitro. Administration of a CRHR2 antagonist after DSS-induced colitis increased disease activity, delayed healing, and decreased epithelial cell proliferation in vivo. Colons from these mice also showed increased apoptosis and proinflammatory cytokine expression. Compared with controls, Crhr2(-/-) mice showed increased mortality in the DSS healing protocol. CRHR2-overexpressing cells had increased proliferation and migration compared with parental cells. Wound healing and signal transducer and activator of transcription 3 activity were elevated in CRHR2-overexpressing cells after urocortin 2 and IL-6 treatment, suggesting advanced healing progression. Our results suggest that selective CRHR2 activation may provide a targeted approach to enhance mucosal repair pathways after colitis.

Diminished expression of CRHR2 in human colon cancer promotes tumor growth and EMT via persistent IL-6/Stat3 signaling

BACKGROUND & AIMS

Chronic inflammation promotes development and progression of colorectal cancer (CRC). We explored the distribution of Corticotropin-Releasing-Hormone (CRH)-family of receptors and ligands in CRC and their contribution in tumor growth and oncogenic EMT.

METHODS

mRNA expression of CRH-family members was analyzed in CRC (N=56) and control (N=46) samples, 7 CRC cell lines and normal NCM460 cells. Immunohistochemical detection of CRHR2 was performed in 20 CRC and 5 normal tissues. Cell proliferation, migration and invasion were compared between Urocortin-2 (Ucn2)-stimulated parental and CRHR2-overexpressing (CRHR2+) cells in absence or presence of IL-6. CRHR2/Ucn2-targeted effects on tumor growth and EMT were validated in SW620-xenograft mouse models.

RESULTS

CRC tissues and cell lines showed decreased mRNA and protein CRHR2 expression compared to controls and NCM460, respectively. The opposite trend was shown for Ucn2. CRHR2/Ucn2 signaling inhibited cell proliferation, migration, invasion and colony formation in CRC-CRHR2+ cells. In vivo, SW620-CRHR2+ xenografts showed decreased growth, reduced expression of EMT-inducers and elevated levels of EMT-suppressors. IL-1b, IL-6 and IL-6R mRNAs where diminished in CRC-CRHR2+ cells, while CRHR2/Ucn2 signaling inhibited IL-6-mediated Stat3 activation, invasion, migration and expression of downstream targets acting as cell cycle- and EMT-inducers. Expression of cell cycle- and EMT-suppressors was augmented in IL-6/Ucn2-stimulated CRHR2+ cells. In patients, CRHR2 mRNA expression was inversely correlated with IL-6R and vimentin levels and metastasis occurrence, while positively associated with E-cadherin expression and overall survival.

CONCLUSIONS

CRHR2 downregulation in CRC supports tumor expansion and spread through maintaining persistent inflammation and constitutive Stat3 activation. CRHR2^low CRC phenotypes are associated with higher risk for distant metastases and poor clinical outcomes.

Pharmacological and alimentary alteration of the gastric barrier

The gastric barrier contains several lines of defence which protect the epithelium from harmful microbes and toxins. Pre-mucosal defence mechanisms include secreted acid (HCl 0.1 mmol/L) and pepsin, which are capable of denaturing tissue. A tightly adherent mucous layer provides the next line of defence, and physically separates any potentially hazardous substance in the lumen from the mucosal surface. Apical secretion of HCO3(-) maintains a non-acidic microenvironment at the mucosal surface. Membrane-bound phospholipids repel soluble toxins, and sulphydryls scavenge reactive oxygen species. However, when noxious agents overwhelm these mechanisms, the epithelium is damaged. Herein, we discuss the pathological and physiological basis for several disease states which are associated with a breakdown in one or more components of the gastric barrier, including: Helicobacter pylori-associated gastritis, atrophic gastritis, stress-related mucosal disease, age-related gastropathy and portal hypertensive gastropathy. The effect of non-steroidal anti-inflammatory drugs and proton pump inhibitors on the gastric mucosa, is explored. Finally, we outline the alterations in mucosal defence caused by alcohol, caffeine, minerals and vitamins.

Intravenous injection of urocortin 1 induces a CRF2 mediated increase in circulating ghrelin and glucose levels through distinct mechanisms in rats

Urocortins (Ucns) injected peripherally decrease food intake and gastric emptying through peripheral CRF(2) receptors in rodents. However, whether Ucns influence circulating levels of the orexigenic and prokinetic hormone, ghrelin has been little investigated. We examined plasma levels of ghrelin and blood glucose after intravenous (iv) injection of Ucn 1, the CRF receptor subtype involved and underlying mechanisms in ad libitum fed rats equipped with a chronic iv cannula. Ucn 1 (10 μg/kg, iv) induced a rapid onset and long lasting increase in ghrelin levels reaching 68% and 219% at 0.5 and 3h post injection respectively and a 5-h hyperglycemic response. The selective CRF(2) agonist, Ucn 2 (3 μg/kg, iv) increased fasting acyl (3h: 49%) and des-acyl ghrelin levels (3h: 30%) compared to vehicle while the preferential CRF(1) agonist, CRF (3 μg/kg, iv) had no effect. Ucn 1's stimulatory actions were blocked by the selective CRF(2) antagonist, astressin(2)-B (100 μg/kg, iv). Hexamethonium (10 mg/kg, sc) prevented Ucn 1-induced rise in total ghrelin levels while not altering the hyperglycemic response. These data indicate that systemic injection of Ucns induces a CRF(2)-mediated increase in circulating ghrelin levels likely via indirect actions on gastric ghrelin cells that involves a nicotinic pathway independently from the hyperglycemic response.

Expression of corticotropin releasing factor receptor type 1 (CRF1) in the human gastrointestinal tract and upregulation in the colonic mucosa in patients with ulcerative colitis

Brain corticotropin-releasing factor (CRF) acting on CRF receptor type 1 (CRF(1)) is a main signaling pathway in the stress response. CRF is also produced in a variety of peripheral sites and acts locally as a proinflammatory mediator. We investigated CRF(1) mRNA expression in the human gastrointestinal tract, and localized CRF(1) immunoreactive cells in the colonic mucosa of healthy subjects and patients with ulcerative colitis (UC). In 4 male healthy subjects (24-29 years), CRF(1) transcript was detected by RT-PCR throughout the gastrointestinal tract with the highest levels in the ileum and rectum and the lowest level in the colon. Immunohistochemistry on whole thickness sigmoid colon sections showed that CRF(1) was localized in the lamina propria and epithelial cells and enteric neurons. In sigmoid colonic biopsies, immunohistochemically double-labeled cells with CRF(1) and CD163, a marker for macrophages, represent 79% of total CRF(1) immunoreactive (IR) cells in healthy subjects. In 10 UC patients, the total number of CRF(1) IR cells and CRF(1)/CD163 double-labeled macrophages was increased by 4.2 and 4.0 folds respectively compared to healthy subjects. These findings indicate that CRF(1) is distributed throughout the GI tract of healthy human subjects. The increase of CRF(1) IR cells prominently in macrophages of the sigmoid colonic mucosa of UC patients provides anatomical support for a role of CRF(1) signaling in modulating the immune-inflammatory process of UC.

Urocortins and CRF type 2 receptor isoforms expression in the rat stomach are regulated by endotoxin: role in the modulation of delayed gastric emptying

Peripheral activation of corticotropin-releasing factor receptor type 2 (CRF(2)) by urocortin 1, 2, or 3 (Ucns) exerts powerful effects on gastric function; however, little is known about their expression and regulation in the stomach. We investigated the expression of Ucns and CRF(2) isoforms by RT-PCR in the gastric corpus (GC) mucosa and submucosa plus muscle (S+M) or laser captured layers in naive rats, their regulations by lipopolysaccharide (LPS, 100 μg/kg ip) over 24 h, and the effect of the CRF(2) antagonist astresssin(2)-B (100 μg/kg sc) on LPS-induced delayed gastric emptying (GE) 2-h postinjection. Transcripts of Ucns and CRF(2b,) the most common wild-type CRF(2) isoform in the periphery, were expressed in all layers, including myenteric neurons. LPS increased Ucn mRNA levels significantly in both mucosa and S+M, reaching a maximal response at 6 h postinjection and returning to basal levels at 24 h except for Ucn 1 in S+M. By contrast, CRF(2b) mRNA level was significantly decreased in the mucosa and M+S with a nadir at 6 h. In addition, CRF(2a), reportedly only found in the brain, and the novel splice variant CRF(2a-3) were also detected in the GC, antrum, and pylorus. LPS reciprocally regulated these variants with a decrease of CRF(2a) and an increase of CRF(2a-3) in the GC 6 h postinjection. Astressin(2)-B exacerbated LPS-delayed GE (42-73%, P < 0.001). These data indicate that Ucn and CRF(2) isoforms are widely distributed throughout the rat stomach and inversely regulated by immune stress. The CRF(2) signaling system may act to counteract the early gastric motor alterations to endotoxemia.

Systemic urocortin 2, but not urocortin 1 or stressin 1-A, suppresses feeding via CRF2 receptors without malaise and stress

BACKGROUND AND PURPOSE

Infusion of corticotropin-releasing factor (CRF)/urocortin (Ucn) family peptides suppresses feeding in mice. We examined whether rats show peripheral CRF/Ucn-induced anorexia and determined its behavioural and pharmacological bases.

EXPERIMENTAL APPROACH

Male Wistar rats (n= 5-12 per group) were administered (i.p.) CRF receptor agonists with different subtype affinities. Food intake, formation of conditioned taste aversion and corticosterone levels were assessed. In addition, Ucn 1- and Ucn 2-induced anorexia was studied in fasted CRF(2) knockout (n= 11) and wild-type (n= 13) mice.

KEY RESULTS

Ucn 1, non-selective CRF receptor agonist, reduced food intake most potently (~0.32 nmol·kg(-1) ) and efficaciously (up to 70% reduction) in fasted and fed rats. The peptides' rank-order of anorexic potency was Ucn 1 ≥ Ucn 2 > >stressin(1) -A > Ucn 3, and efficacy, Ucn 1 > stressin(1) -A > Ucn 2 = Ucn 3. Ucn 1 reduced meal frequency and size, facilitated feeding bout termination and slowed eating rate. Stressin(1) -A (CRF(1) agonist) reduced meal size; Ucn 2 (CRF(2) agonist) reduced meal frequency. Stressin(1) -A and Ucn 1, but not Ucn 2, produced a conditioned taste aversion, reduced feeding efficiency and weight regain and elicited diarrhoea. Ucn 1, but not Ucn 2, also increased corticosterone levels. Ucn 1 and Ucn 2 reduced feeding in wild-type, but not CRF(2) knockout, mice.

CONCLUSIONS AND IMPLICATIONS

CRF(1) agonists, Ucn 1 and stressin(1) -A, reduced feeding and induced interoceptive stress, whereas Ucn 2 potently suppressed feeding via a CRF(2) -dependent mechanism without eliciting malaise. Consistent with their pharmacological differences, peripheral urocortins have diverse effects on appetite.

Different effects of corticotropin-releasing factor and urocortin 2 on apoptosis of prostate cancer cells in vitro

Urocortin (Ucn), a corticotropin-releasing factor (CRF)-related neuropeptide binding both CRF type 1 receptor (CRFR1) and CRFR2, has recently been found in prostate cancer. However, no report has yet been known to elucidate the roles of Ucn in prostate cancer via the two receptors. In this study, the expression of both CRFR1 and CRFR2 in the mouse prostate cancer cell line RM-1 were detected and cellular apoptosis was monitored in the presence of CRF or Ucn2, the CRFR1- and CRFR2-selective agonist respectively. CRF promoted apoptosis while Ucn2 exerted the opposite effect. CRF reduced Bcl-2 expression, induced Bax expression, and hyperpolarized the mitochondrial membrane potential to activate caspase-9. On the contrary, Ucn2 increased Bcl-2 expression and decreased Bax expression, in which phosphorylation of Akt and cyclic AMP response element-binding (CREB) was involved. Pretreatment with phosphatidylinositide 3-kinase/Akt inhibitor (LY-294002) prior to Ucn2 led to downregulation of CREB phosphorylation and hence reduced Bcl-2 expression. These effects of CRF and Ucn2 were abolished by antalarmin (Anta) and antisauvagine-30, the CRFR1- and CRFR2-selective antagonist respectively. In LNCaP cell line, similar effects on cell apoptosis by CRF and Ucn2 were observed. In summary, our results demonstrated CRFR1 and CRFR2 expression in prostate cancer and indicated the opposite apoptotic roles of the two different CRFRs. These data may contribute to uncovering the pathophysiological function of endogenous Ucn in prostate tumorigenesis and progression.

Urocortin and corticotropin-releasing factor receptor 2 in human renal cell carcinoma: disruption of an endogenous inhibitor of angiogenesis and proliferation

Purpose

Urocortin (Ucn) exerts its actions through activation of two corticotropin-releasing factor receptors (CRFRs), CRFR1 and CRFR2. Involvement of Ucn/CRFR2 system in pathophysiological conditions such as the regulation of angiogenesis and inhibition of proliferation has been already reported. Suppression of neovascularization through reduction of vascular endothelial growth factor and inhibition of tumor cell cycling is modulated mainly through activation of CRFR2. To find out a possible involvement of Ucn/CRFR2 in kidney tumor, we examined the expression of Ucn and CRFR2 in normal and tumoral kidney specimens.

Methods

We applied reverse transcriptase PCR (n = 14), immunofluorescence (IF) on tissue microarrays (n = 25) and confocal microscopy to examine the mRNA expression and peptide/protein localization of Ucn and CRFR2 in normal kidney versus clear cell renal cell carcinoma, respectively.

Results

Ucn and CRFR2 mRNAs are expressed in normal and tumor specimens. In normal tissue, IF showed a cytoplasmic staining of Ucn mainly in proximal tubules, whereas a diffuse nuclear staining with diverse intensity was observed in tumoral tissues. CRFR2 was detected in proximal tubules and vasculature of normal specimens. Intriguingly, an almost complete loss of CRFR2 was observed in epithelial cells and microvessels within tumor tissues.

Conclusions

Here, and for the first time, we show the expression of Ucn and CRFR2 in human kidney and renal cell carcinoma. We propose that the nuclear translocation of Ucn along with the loss of CRFR2 in epithelial cells and microvasculature of tumoral specimens may be involved in the pathobiology of renal cell carcinoma.

Corticotrophin-releasing factor, related peptides, and receptors in the normal and inflamed gastrointestinal tract

Corticotrophin-releasing factor (CRF) is mainly known for its role in the stress response in the hypothalamic–pituitary–adrenal axis. However, increasing evidence has revealed that CRF receptor signaling has additional peripheral effects. For instance, activation of CRF receptors in the gastrointestinal tract influences intestinal permeability and motility. These receptors, CRF1 and CRF2, do not only bind CRF, but are also activated by urocortins. Most interestingly, CRF-related signaling also assumes an important role in inflammatory bowel diseases in that it influences inflammatory processes, such as cytokine secretion and immune cell activation. These effects are characterized by an often contrasting function of CRF1 and CRF2. We will review the current data on the expression of CRF and related peptides in the different regions of the gastrointestinal tract, both in normal and inflamed conditions. We next discuss the possible functional roles of CRF signaling in inflammation. The available data clearly indicate that CRF signaling significantly influences inflammatory processes although there are important species and inflammation model differences. Although further research is necessary to elucidate this apparently delicately balanced system, it can be concluded that CRF-related peptides and receptors are (certainly) important candidates in the modulation of gastrointestinal inflammation.

Distinct distribution of corticotropin releasing factor receptors in human breast cancer

The hypothalamic neuropeptide corticotropin releasing factor (CRF) has been found in several types of human cancer, where its biological role is not clarified. In experimental models of breast cancer CRF has been shown to exert anti-proliferative and other actions. Aim of the present study was to describe the expression of the two types of CRF receptors CRF(1) and CRF(2) in human breast tumors. Receptor expression was studied in breast biopsies from patients diagnosed for primary breast adenocarcinoma, obtained from the tumor and the adjacent benign tissue. Gene expression levels were evaluated by real-time PCR following reverse transcription of total RNA extracts. CRF(1) transcripts were found in 23.1% of benign and in 23.1% of malignant biopsies. CRF(2(a)) was found in 22.2% of benign and 36.0% of malignant biopsies. Transcript levels of both receptors did not differ significantly between cancer and benign biopsies from the same tumor. No correlation was found between CRF receptor expression and patient histo/clinicopathological characteristics. Histological mapping using immunohistochemistry revealed positive CRF(1) immunostaining in the cancerous implants and breast ducts, whereas CRF(2) immunoreactivity was localized mainly in the perineural invasions. In conclusion, both CRF receptors were found in breast cancer and the respective benign adjacent tissue. The two CRF receptor proteins presented distinct distribution and subcellular localization, pointing into differing biological roles. CRF receptors could serve as targets of endogenous ligands expressed in the tumor microenvironment, regulating cancer growth.

Corticotropin-releasing hormone receptors mediate opposing effects in cholestasis-induced liver cell apoptosis

CRH receptors are expressed in human and rat liver. The current study investigated the biological role of the CRH system in the hepatocellular apoptotic process and aimed to reveal the responsible molecular mechanisms. Using a rat experimental model of common bile duct surgical ligation leading to obstructive jaundice and cholestasis, liver apoptosis was induced in the hepatic parenchyma as confirmed by the elevated expression of the early apoptotic neoepitope M30. This effect was reversed by administration of the nonselective CRH antagonist astressin but not by the selective CRH(2) antagonist astressin2B, suggesting that antagonism of the endogenous CRH(1) blocked the cholestasis-induced apoptotic mechanism. No effect was observed in the noncholestasis controls. In our experimental model, early and late apoptosis-preventing markers were induced in parallel to apoptosis; elevated gene transcript levels of the anti-apoptotic bcl-2 were found by real-time PCR in the first postoperative day and increased serum hepatocyte growth factor levels were measured by ELISA in the third postoperative day. Selective CRH(2) antagonism reversed the elevated expression of bcl-2 and hepatocyte growth factor, suggesting that this receptor type mediated antiapoptotic actions of the endogenous CRH system, opposing the preapoptotic ones mediated by CRH(1). In conclusion, the present study indicated that the CRH neuroendocrine system regulates cholestasis-induced apoptosis in the hepatic parenchyma via receptor-specific pathways. These data may contribute to better understanding of the CRH biology and its pathophysiological significance in the periphery.

The corticotropin releasing factor system in cancer: expression and pathophysiological implications

Malignant tumors express multiple factors that have some role in the regulating networks supporting their ectopic growth. Recently, increased interest has been developing in the expression and biological role of the neuropeptides and receptors of the corticotropin releasing factor (CRF) system, the principal neuroendocrine mediator of the stress response, especially in the light of several R&D programs for small molecule antagonists that could present some anticancer therapeutic benefit. In the present article, we review the literature suggesting that the CRF system could be involved in the regulation of human cancer development. Potential implication in growth, metastasis, angiogenesis, or immune parameters via activation of locally expressed receptors could be clinically exploited by presenting targets of new therapeutic approaches.

The corticotropin-releasing factor system in inflammatory bowel disease: prospects for new therapeutic approaches

Mounting evidence suggests that stress is implicated in the development of inflammatory bowel disease (IBD), via initial nervous disturbance and subsequent immune dysfunction through brain-gut interactions. The corticotropin-releasing factor (CRF) system, being the principal neuroendocrine coordinator of stress responses, is involved in the inflammatory process within the gastrointestinal tract, via vagal and peripheral pathways, as implied by multiple reports reviewed here. Blocking of CRF receptors could theoretically exert beneficial anti-inflammatory effects in colonic tissues. The recently synthesised small-molecule CRF(1) antagonists or alternatively non-peptide CRF(2) antagonists when available, may become new reliable options in the treatment of IBD.

The involvement of altered corticotropin releasing factor receptor 2 expression in prostate cancer due to alteration of anti-angiogenic signaling pathways

BACKGROUND

Expression of urocortin (Ucn) in the human benign prostate and prostate cancer has been reported recently. Ucn binds and activates corticotropin releasing factor (CRF) receptor 1 (CRFR1) and 2 (CRFR2). Activation of CRFR2 has been shown to inhibit tumor growth by regulation of proliferation and apoptosis as well as suppression of vascularization. However, there is no report demonstrating expression profile of CRFR2 in normal prostate versus prostate cancer.

METHODS

CRFR2 mRNA expression was assessed in human normal prostate and prostate cancer by reverse transcriptase PCR. CRFR2 expression on protein level has been performed using double staining immunofluorescence (IF) of tissue microarrays of 32 cases of prostatic adenocarcioma with corresponding normal tissues. Confocal microscopy was carried out to visualize the immunostaining.

RESULTS

PCR of normal prostate lysates exhibited specific signals for CRFR2 mRNA. However PCR of lysates of prostate cancer exhibited no signal for CRFR2 mRNA. IF study exhibited that smooth muscle components of the stroma and endothelial cells of blood vessels express an extensive staining for CRFR2. In a lesser extend vascular smooth muscle cells expressed CRFR2. The tumoral neovascular system and stroma exhibited no immunopositivity for CRFR2.

CONCLUSIONS

The present study demonstrates for the first time that human benign prostate tissue and prostate cancer specimen differentially express CRFR2. While Ucn expression in prostate cancer has been shown to be identical to non-malignant prostate tissues, we hypothesize that expression loss of CRFR2 in prostate cancer and its neovascularization contributes to prostate tumorigenesis, progression, and neoangiogenesis.

Gastric mucosal defense and cytoprotection: bench to bedside

The gastric mucosa maintains structural integrity and function despite continuous exposure to noxious factors, including 0.1 mol/L HCl and pepsin, that are capable of digesting tissue. Under normal conditions, mucosal integrity is maintained by defense mechanisms, which include preepithelial factors (mucus-bicarbonate-phospholipid "barrier"), an epithelial "barrier" (surface epithelial cells connected by tight junctions and generating bicarbonate, mucus, phospholipids, trefoil peptides, prostaglandins (PGs), and heat shock proteins), continuous cell renewal accomplished by proliferation of progenitor cells (regulated by growth factors, PGE(2) and survivin), continuous blood flow through mucosal microvessels, an endothelial "barrier," sensory innervation, and generation of PGs and nitric oxide. Mucosal injury may occur when noxious factors "overwhelm" an intact mucosal defense or when the mucosal defense is impaired. We review basic components of gastric mucosal defense and discuss conditions in which mucosal injury is directly related to impairment in mucosal defense, focusing on disorders with important clinical sequelae: nonsteroidal anti-inflammatory drug (NSAID)-associated injury, which is primarily related to inhibition of cyclooxygenase (COX)-mediated PG synthesis, and stress-related mucosal disease (SRMD), which occurs with local ischemia. The annual incidence of NSAID-associated upper gastrointestinal (GI) complications such as bleeding is approximately 1%-1.5%; and reductions in these complications have been demonstrated with misoprostol, proton pump inhibitors (PPIs) (only documented in high-risk patients), and COX-2 selective inhibitors. Clinically significant bleeding from SRMD is relatively uncommon with modern intensive care. Pharmacologic therapy with antisecretory drugs may be used in high-risk patients (eg, mechanical ventilation >or=48 hours), although the absolute risk reduction is small, and a decrease in mortality is not documented.

Gastrointestinal peptides controlling body weight homeostasis

Obesity has become an international public health problem. Unfortunately, effective treatment options are limited. In the last 20 years, research in obesity and associated pathologies has derived in a significant increase in the knowledge of the physiological and molecular mechanism regulating body mass, such as gastrointestinal-neuroendocrine communications. Gut-brain peptides may provide attractive therapeutic targets against this disease. This review summarizes research into energy balance through gastrointestinal tract peptides. Understanding these molecular mechanisms will provide new pharmacological targets for the treatment of obesity and appetite disorders.

Corticotropin-releasing factor family and its receptors: tumor therapeutic targets?

Urocortin (UCN) and corticotropin-releasing factor (CRF) are members of CRF family. Though CRF is mainly distributed in central nervous system (CNS), UCN has been reported to play biologically diverse roles in several systems such as cardiovascular, respiratory, digestive, reproductive, stress, immunologic system, etc. UCN and CRF bind to two known receptors, CRFR1 and CRFR2, to function. Both CRF receptors are distributed in CNS and periphery tissues, and their expression in cancer tissues has been reported. Now there are many documents indicating UCN/CRF play an important role in the regulation of carcinogenesis. There is also evidence indicating UCN/CRF have anticancer effects via CRFRs. This paper will review the effects of CRF family in cancers.