Adrenomedullin mRNA Expression Research Articles

Expression profile of adrenomedullin and its specific receptors in liver tissues from patients with hepatocellular carcinoma and in tumorigenic cell line-secreted extracellular vesicles.

The transcriptional profile of adrenomedullin (AM), a new metastasis-related factor involved in hepatocellular carcinoma (HCC), and its specific receptors (CLR, RAMP1, RAMP3) were evaluated in liver tissues of HCV-positive HCC subjects undergoing liver transplantation (LR) and in donors (LD). AM and its specific receptor expression were also assessed in extracellular vesicles (EVs) secreted by tumorigenic (HepG2) and non-tumorigenic (WRL68) cells by Real-Time PCR. AM expression resulted significantly elevated in LR concerning LD (p=0.0038) and, for the first time, significantly higher levels in HCC patients as a function of clinical severity (MELD score), were observed. RAMP3 and CLR expression increased in LR as a function of clinical severity while RAMP1 decreased. Positive correlations were found among AM, its receptors, and apoptotic markers. No AM mRNA expression difference was observed between HepG2 and WRL68 EVs. RAMP1 and RAMP3 resulted lower in HepG2 concerning WRL68 while significantly higher levels were observed for CLR. While results at tissue level characterize AM as a regulator of carcinogenesis-tumor progression, those obtained in EVs do not indicate AM as a target candidate, neither as a pathological biomarker nor as a marker involved in cancer therapy.

Adrenomedullin is an Important Pathological Mediator in Progression of Chronic Neuropathic Pain.

The characterization of neuropathic pain is maladaptive plasticity within the nociceptive system. Multiple alterations contribute to complex pain phenotypes. Adrenomedullin (AM) has been documented to be a pain mediator. However, its involvement in pathological pain is poorly understood. We studied the contribution of AM to chronic neuropathic pain in the spinal nerve ligation (SNL) model. Daily injection of the AM receptor antagonist AM22-52 (10 nmol) via an intrathecal (i.t.) route after SNL inhibited mechanical allodynia starting on day 6. Single administration of AM22-52 produced an immediate attenuation on pain hypersensitivity on day 2 or 10 post-SNL. Protein and mRNA levels were assayed by immunofluorescent staining and qRT-PCR, respectively, on days 1, 3, 7 and 15 post-SNL. The results showed that AM at both protein and mRNA levels was increased in both injured (L5) and adjacent uninjured (L4) nerves starting on day 3 post-SNL. In dorsal root ganglion (DRG) at L5, AM was increase on days 1-7 at mRNA level but only on day 7 at protein level. However, AM was increase at mRNA level on days 1-7 and at protein level on days 3-15 in L4 DRG. AM mRNA expression was upregulated on days 1-7 in the spinal cord. Expression of receptor activity-modifying protein 2 (RAMP2), an essential AM1 receptor component, was upregulated in small and medium-diameter neurons on days 1-15 in both L5 and L4 DRG. Furthermore, single administration of AM22-52 suppressed the increase of nNOS in DRG induced by SNL and daily injection of AM22-52 for 7 days inhibited SNL-induced increase of CGRP mRNA in the spinal dorsal horn. This study indicates that the increased AM bioactivity in injured and uninjured peripheral nerves, uninjured adjacent DRG and the spinal dorsal horn play a critical role mainly in the late-phase development of neuropathic pain. The mechanism may involve the recruitment of nNOS and CGRP.

Increased tryptase expression in HαT is associated with upregulation of epithelia-derived MRGPRX2 agonists and MRGPRX2+ MCs in the GI mucosa

Abstract Hereditary α-tryptasemia (HαT) is a genetic trait characterized by elevated serum tryptase and increased copy number of the TPSAB1 gene. It is associated with flushing, itching, GI symptoms and anaphylaxis. HαT gut epithelia undergo increased rates of pyroptosis, and HαT gut mast cells (MCs) are increased in number with highly expressed FCER1 and CD203C. Gut MCs express Mas-related G protein–coupled receptor-X2 (MRGPRX2). Studies have clearly shown that this receptor contributes to host defense, mediates pseudo-allergy, and is involved in a number of atopic skin conditions. Herein, we sought to evaluate the impact of MRGPRX2 in individuals with HαT and GI symptoms. We observed increased numbers of MRGPRX2+ mast cells in HαT versus non-HαT gastrointestinal (GI) biopsies (colon->duodenum->stomach->Ileum). mRNA expression of tryptase and MRGPRX2 in intestine of HαT increased ~6-fold and 3-fold respectively over non-HαT biopsies. Epithelial derived agonists of MGPRX2 including human beta defensin (HBD) 2 and adrenomedullin (PAMP12) mRNA expression were also found to be upregulated ~2-fold and ~3-folds in HαT over non-HαT biopsies. MC protease carboxydeptidase-3 was also increased. Taken together, this data suggests that in addition to upregulation of MRGPRX2 in MCs, increased tryptase expression in HαT leads to upregulation of MRGPRX2 agonists and modifiers in gut epithelial cells, nociceptors and MCs, and results in GI symptoms. This work was supported by National Institutes of Health grants R01-AI124182, R01-AI143185 and R01-AI149487 to Hydar Ali.

Upregulated expression of hypoxia reactive genes in peripheral blood mononuclear cells from chronic liver disease patients

Liver fibrosis induces intrahepatic microcirculation disorder and hypoxic stress. Hypoxic stress has the potential for an increase in the possibility of more liver fibrosis and carcinogenesis. Liver biopsy is a standard method that evaluates of intrahepatic hypoxia, however, is invasive and has a risk of bleeding as a complication. Here, we investigated the hypoxia reactive gene expressions in peripheral blood mononuclear cells (PBMC) from chronic liver disease patients to evaluate intrahepatic hypoxia in a non-invasive manner. The subjects enrolled for this study were composed of 20 healthy volunteers (HV) and 48 patients with chronic liver disease (CLD). CLD patients contained 24 patients with chronic hepatitis（CH）and 24 patients with liver cirrhosis (LC). PBMC were isolated from heparinized peripheral blood samples. We measured the transcriptional expression of hypoxia reactive genes and inflammatory cytokines by quantitative RT-PCR. mRNA expression of adrenomedullin (AM), vascular endothelial growth factor A (VEGFA) superoxide dismutase (SOD), glutathione peroxidase (GPx) (p < 0.05), Interleukin-6 (IL-6), transforming growth factor-beta (TGF-β) and heme oxygenase-1 (HO-1) in CLD group were significantly higher than HV. AM mRNA expression is correlated with serum lactate dehydrogenase (LDH), serum albumin (Alb), IL6, and SOD mRNA expression. The hypoxia reactive gene expression in PBMCs from CLD patients was more upregulated than HV. Especially, angiogenic genes were notably upregulated and correlated with liver fibrosis. Here, we suggest that mRNA expression of AM in PBMCs could be the biomarker of intrahepatic hypoxia.

Hyperoxia exposure disrupts adrenomedullin signaling in newborn mice: Implications for lung development in premature infants

Hyperoxia contributes to the development of bronchopulmonary dysplasia (BPD), a chronic lung disease of human infants that is characterized by disrupted lung angiogenesis. Adrenomedullin (AM) is a multifunctional peptide with angiogenic and vasoprotective properties. AM signals via its cognate receptors, calcitonin receptor-like receptor (Calcrl) and receptor activity-modifying protein 2 (RAMP2). Whether hyperoxia affects the pulmonary AM signaling pathway in neonatal mice and whether AM promotes lung angiogenesis in human infants are unknown. Therefore, we tested the following hypotheses: (1) hyperoxia exposure will disrupt AM signaling during the lung development period in neonatal mice; and (2) AM will promote angiogenesis in fetal human pulmonary artery endothelial cells (HPAECs) via extracellular signal-regulated kinases (ERK) 1/2 activation. We initially determined AM, Calcrl, and RAMP2 mRNA levels in mouse lungs on postnatal days (PND) 3, 7, 14, and 28. Next we determined the mRNA expression of these genes in neonatal mice exposed to hyperoxia (70% O2) for up to 14 d. Finally, using HPAECs, we evaluated if AM activates ERK1/2 and promotes tubule formation and cell migration. Lung AM, Calcrl, and RAMP2 mRNA expression increased from PND 3 and peaked at PND 14, a time period during which lung development occurs in mice. Interestingly, hyperoxia exposure blunted this peak expression in neonatal mice. In HPAECs, AM activated ERK1/2 and promoted tubule formation and cell migration. These findings support our hypotheses, emphasizing that AM signaling axis is a potential therapeutic target for human infants with BPD.

Adrenomedullin mediates tumor necrosis factor-α-induced responses in dorsal root ganglia in rats

Adrenomedullin (AM), a member of the calcitonin gene-related peptide (CGRP) family, has been demonstrated to be a pain peptide. This study investigated the possible involvement of AM in tumor necrosis factor-alpha (TNF-α)-induced responses contributing to neuronal plasticity in the dorsal root ganglia (DRG). Exposure of the DRG explant cultures to TNF-α (5nM) for 48h upregulated the expression of AM mRNA. The treatment with TNF-α also increased the level of CGRP, CCL-2 and MMP-9 mRNA in the cultured DRG. This increase was attenuated by the co-treatment with the selective AM receptor antagonist AM22-52 (2μM). The blockade of AM receptors inhibited TNF-α-induced increase of the glial fibrillary acidic protein (GFAP), interleukin-1β (IL-1β), phosphorylated cAMP response element binding protein (pCREB) and nuclear factor kappa B (pNF-κB) proteins. On the other hand, the treatment with the AM receptor agonist AM1-50 (10nM) for 96h induced an increase in the level of GFAP, IL-1β, pCREB and pNF-κB proteins. The inhibition of AM activity did not change TNF-α-induced phosphorylation of extracellular signal-related kinase (pERK) while the treatment with AM1-50 still increased the level of pERK in the cultured DRG. Immunofluorescence assay showed the colocalization of AM-like immunoreactivity (IR) with TNF-α-IR in DRG neurons. The present study suggests that the increased AM receptor signaling mediated the many, but not all, TNF-α-induced activities, contributing to peripheral sensitization in neuropathic pain.

Ulipristal acetate resembles mifepristone in modulating human fallopian tube function.

Do ulipristal acetate (UPA) and mifepristone have an effect on ciliary beat frequency and muscular contractions in the human Fallopian tube? UPA, in resemblance to mifepristone, inhibits ciliary beat and muscular contraction of the human Fallopian tube, probably through an agonistic effect on the tubal progesterone receptor. UPA, like mifepristone, acts as an emergency contraceptive mainly by inhibiting ovulation. Little is known about its effects on tubal function. This was an in vitro experimental study using Fallopian tube samples collected from 11 women undergoing hysterectomy for benign non-tubal gynaecological conditions. The tubal epithelium and longitudinal smooth muscle fibres were isolated, cultured and treated with UPA at graded concentrations of 0, 20, 200 and 2000 ng/ml, and mifepristone at graded concentrations of 0, 300, 3000 and 30 000 ng/ml, respectively. After treatment, ciliary beat frequency was determined using a photometric method. Basal tone, amplitude and frequency of muscular contraction were recorded through a force transducer. The mRNA expression of progesterone receptor (total and PR-B isoform), glycodelin and adrenomedullin were determined by real-time quantitative PCR. There was an overall dose-dependent suppressive effect on ciliary beat frequency (P < 0.0001) after treatment with UPA at all concentrations and with mifepristone at 3000 ng/ml or above. The basal tone, amplitude and frequency of muscular contractions were significantly reduced (P < 0.05) after treatment with UPA at 200 ng/ml or above, and with mifepristone at 3000 ng/ml or above. UPA treatment at 200 ng/ml or above significantly up-regulated the mRNA expression of progesterone receptor and glycodelin and down-regulated the mRNA expression of adrenomedullin in Fallopian tube tissue (P < 0.05). Whether or not the tubal effect may translate into additional mechanisms for contraceptive action in vivo is uncertain. The clinical relevance of UPA with regard to contraceptive activity is worthy of further exploration. The study was supported by a Seed Fund from the Centre of Reproduction, Development and Growth, Faculty of Medicine, the University of Hong Kong. All authors have no competing interest to declare.

Pharmacological characterisation of the mechanisms underlying the relaxant effect of adrenomedullin in the rat carotid artery.

We investigated the mechanisms underlying the relaxant effect of adrenomedullin (AM) in the rat carotid artery and verified the expression of AM system components in this tissue. The carotid artery was isolated from male Wistar rats and immunohistochemical, Western immunoblotting, real-time polymerase chain reaction and functional assays were conducted. Protein and mRNA expression of AM, calcitonin receptor-like receptor (CRLR) and receptor activity-modifying proteins (RAMP)1, 2, 3 were detected in carotid segments from male Wistar rats. Immunohistochemical assays showed that AM and CRLR receptors are expressed in the endothelium and smooth muscle cells. Functional assays showed that AM concentration dependently relaxed carotid rings with intact endothelium. Endothelial removal reduced, but not abolished, the relaxation induced by AM. AM22-52 (selective antagonist for AM receptors) and calcitonin gene-related peptide (CGRP)8-37 (selective CGRP receptor antagonist) reduced AM-induced relaxation in endothelium-intact rings. Pre-incubation of endothelium-intact rings with N-nitro-L-arginine methyl ester, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one or Rp-8-Bromo-?-phenyl-1,N2-ethenoguanosine 3',5'cyclic monophosphorothioate reduced AM-induced relaxation. Inhibition of cyclooxygenase-1 and protein kinase A (PKA) reduced AM-induced relaxation. The relaxation induced by AM was attenuated by the K(+) channel blockers apamin and glibenclamide. AM increased nitrate levels and 6-keto-prostaglandin F1α (stable product of prostacyclin) in the rat carotid. In endothelium-denuded rings, AM22-52 , glibenclamide and PKA inhibition by H89 reduced AM-induced relaxation. The novelty of this work is that it first demonstrated functionally that AM-induced relaxation is mediated by AM and CGRP receptors located on the endothelium and AM receptors located on smooth muscle of rat carotid arteries. AM-induced relaxation involves the nitric oxide-cGMP pathway, a vasodilator prostanoid, the opening of K(+) channels and the activation of PKA.

Hypoxia-Inducible Factor and Target Gene Expression Are Decreased in Patients With Sepsis

Background Hypoxia-inducible factor-1 (HIF-1) is a molecular key player in response to hypoxemic/inflammatory conditions prevailing in sepsis. In a prospective observational study, we tested the hypotheses that sepsis affects HIF-1α messenger ribonucleic acid (mRNA) expression (primary hypothesis) and also (secondary hypotheses) the expression of the HIF-1α target genes adrenomedullin and β2-integrins. Furthermore, we tested that lipopolysaccharide administration increases HIF-1α mRNA and protein in naive and endotoxin-tolerant monocytes. Methods In 99 patients with sepsis and 48 healthy volunteers, leukocyte HIF-1α mRNA expression (real-time polymerase chain reaction), cytokine concentrations (enzymelinked immunosorbent assay), and intracellular distribution of HIF-1α protein (immunofluorescence staining) were assessed. In vitro, HIF-1α mRNA expression and protein were measured in naive or endotoxin-tolerant (48 h; 0.05 ng/ml lipopolysaccharide) monocytes, with/without additional lipopolysaccharide (6h; 1 μg/ml). Results In comparison to healthy volunteers, HIF-1α mRNA expression (-67%; P = 0.0001) and HIF-1α protein positive cells (-66.7%; P = 0.01) were decreased in sepsis. mRNA expression of adrenomedullin (-75%), CD11a (-85%), and CD11b (-86%; all P = 0.0001) was also decreased. In contrast, interleukin 6 (P = 0.0001), interleukin 10 (P = 0.0001), and tumor necrosis factor-α (P = 0.0002) concentrations were increased. Of note, HIF-1α mRNA expression was inversely associated with illness severity (Simplified Acute Physiology Score II; r = -0.29; P = 0.0001). In vitro, acute lipopolysaccharide administration of naive monocytic cells increased HIF-1α mRNA expression, whereas HIF-1α mRNA and protein (-60%; P = 0.001) were decreased in endotoxin-tolerant cells, which still up regulated cytokines. Conclusions In sepsis, HIF-1α mRNA expression was suppressed and inversely associated with illness severity. While acute lipopolysaccharide administration increased HIF-1α mRNA expression, prolonged stimulation suppressed HIF-1α expression. The clinical implications of decreased HIF-1α may include maladaption to tissue hypoxia or depressed immune function.

Changes of hypoxia-inducible factor-1α, endothelin-1 and adrenomedullin in newborn rats with hypoxia-induced pulmonary hypertension

Objective To provide the foundation of theory on prevention of hypoxia-induced pulmonary hypertension(HPH) by investigating the concentrations in the serum and expression levels in the lung tissue, and by studying the roles of hypoxia-inducible factor-1α(HIF-1α), endothelin-1(ET-1) and adrenomedullin (ADM) in newborn rats with HPH. Methods Seventy-two newborn rats were randomly divided into hypoxic group(hypoxia exposure) and normoxic group.The mean pulmonary arteria pressure(mPAP), concentrations in the serum and expression levels in the lung tissue of the above-mentioned factors were measured in these neonatal rats after 3, 5, 7, 10, 14 and 21 days, including hypoxic group and normoxic group, respectively.The morphology of pulmonary arterioles was observed and the vascular remodeling indexes were measured. Results 1.Compared with the normoxic group, the mPAP increased with the prolonged hypoxic time in the hypoxic group(P<0.05).2.Concentrations in the serum and expression levels in the lung tissue of HIF-1α were higher than those of the normoxic group on 3, 5, 7, 10, 14 days(all P<0.05). The serum concentration of ET-1 elevated significantly in the hypoxic group at each time point, and ET-1 mRNA increased only on 3 and 5 days of the hypoxia group.The serum concentration of ADM level in the hypoxic group was higher than that of the normoxic group on 3 and 5 days, but lower than the normoxic group after 14 and 21 days of hypoxia, and the expression of ADM mRNA in the lung tissue was higher on 3 and 5 days in the hypoxic group.3.Morphology and ultrastructure of the pulmonary arteries change were found after 7 days of hypoxia exposure. Conclusions HIF-1α may regulate ET-1 and ADM in the pathogenesis of HPH.ET-1 plays a powerful role by pulmonary vasoconstriction and vascular remodeling, whereas ADM displays the protective effects on blood vessels in the early stages of HPH.Pulmonary vascular remodeling occurs in the hypoxic group after 7 days of hypoxia. Key words: Hypoxia-inducible factor-1α; Endothelin-1; Adrenomedullin; Hypertension; Rat

Intermedin protects against ischaemia and reperfusion injury in human ventricular cardiomyocytes: receptor subtype involvement

Purpose: Early reperfusion following myocardial infarction is essential but results in ischaemia/reperfusion (I/R) injury, whereby myocardial cells die largely due to oxidative stress. Intermedin (IMD; adrenomedullin-2), a novel peptide related to adrenomedullin (AM), is up-regulated in cardiovascular disease and is protective against I/R injury in rodent hearts and human coronary microvascular endothelial cells and cardiac non-myocytes. Protection is dependent on calcitonin receptor-like receptor (CRLR) signalling in association with one of three receptor activity-modifying proteins (RAMPs). IMD has yet to be investigated in human cardiomyocytes for a cardioprotective role. Aims: To identify if IMD and its receptor components are expressed in human ventricular cardiomyocytes; to investigate whether IMD protects these cells against simulated I/R injury and if so, determine receptor subtype involvement. Methods: Left ventricular adult human cardiomyocytes (HCM) were subjected to normoxia or simulated ischaemia for 4 h or I/R (3 h normoxia followed by 1 h reperfusion) all in the absence or presence of IMD. Cell viability was assessed using Trypan blue dye exclusion and oxidative damage by commercial Oxyblot assay. mRNA expression and protein distribution of IMD, AM, CRLR and RAMPs1-3 were assessed by Quantitative Real-Time PCR and indirect immunofluorescence microscopy, respectively. The silencing of the peptides or their receptor components using siRNA knock-down was employed to determine endogenous peptide and receptor subtype involvement in protection against I/R. Results: IMD, AM and their receptor component mRNAs were expressed in HCM; RAMP2 was the most abundant RAMP, while IMD was less abundantly expressed than AM. Ischaemia or I/R reduced the HCM cell count by 40% and 60% respectively (p<0.05 for both). IMD (10-9 mol.L-1) protected against the deleterious effects of ischaemia and I/R injury (∼20% salvaged for both conditions, p<0.05), with preservation of cell structure when examined by phase contrast microscopy and decreased oxidative stress noted on Oxyblot (p<0.001 vs. non-IMD counterpart for ischaemia or I/R). Protection was greatest when IMD was given during reperfusion (p<0.001) and was abolished by silencing CRLR (p<0.05) and RAMP2 (p<0.001). However, silencing endogenous IMD and/or AM expression did not augment extent of I/R injury in HCM. Conclusion: Exogenous IMD is protective against I/R in HCM, attributed to AM1 receptor subtype involvement. IMD administration during cardiac reperfusion could improve levels of morbidity and mortality in patients following myocardial infarction.

Hypoxia-inducible Factor and Target Gene Expression Are Decreased in Patients with Sepsis

Hypoxia-inducible factor-1 (HIF-1) is a molecular key player in response to hypoxemic/inflammatory conditions prevailing in sepsis. In a prospective observational study, we tested the hypotheses that sepsis affects HIF-1α messenger ribonucleic acid (mRNA) expression (primary hypothesis) and also (secondary hypotheses) the expression of the HIF-1α target genes adrenomedullin and β2-integrins. Furthermore, we tested that lipopolysaccharide administration increases HIF-1α mRNA and protein in naive and endotoxin-tolerant monocytes. In 99 patients with sepsis and 48 healthy volunteers, leukocyte HIF-1α mRNA expression (real-time polymerase chain reaction), cytokine concentrations (enzymelinked immunosorbent assay), and intracellular distribution of HIF-1α protein (immunofluorescence staining) were assessed. In vitro, HIF-1α mRNA expression and protein were measured in naive or endotoxin-tolerant (48 h; 0.05 ng/ml lipopolysaccharide) monocytes, with/without additional lipopolysaccharide (6h; 1 μg/ml). In comparison to healthy volunteers, HIF-1α mRNA expression (-67%; P = 0.0001) and HIF-1α protein positive cells (-66.7%; P = 0.01) were decreased in sepsis. mRNA expression of adrenomedullin (-75%), CD11a (-85%), and CD11b (-86%; all P = 0.0001) was also decreased. In contrast, interleukin 6 (P = 0.0001), interleukin 10 (P = 0.0001), and tumor necrosis factor-α (P = 0.0002) concentrations were increased. Of note, HIF-1α mRNA expression was inversely associated with illness severity (Simplified Acute Physiology Score II; r = -0.29; P = 0.0001). In vitro, acute lipopolysaccharide administration of naive monocytic cells increased HIF-1α mRNA expression, whereas HIF-1α mRNA and protein (-60%; P = 0.001) were decreased in endotoxin-tolerant cells, which still up regulated cytokines. In sepsis, HIF-1α mRNA expression was suppressed and inversely associated with illness severity. While acute lipopolysaccharide administration increased HIF-1α mRNA expression, prolonged stimulation suppressed HIF-1α expression. The clinical implications of decreased HIF-1α may include maladaption to tissue hypoxia or depressed immune function.

An Angiogenic Role for Adrenomedullin in Choroidal Neovascularization

PurposeAdrenomedullin (ADM) has been shown to take part in physiological and pathological angiogenesis. The purpose of this study was to investigate whether ADM signaling is involved in choroidal neovascularization (CNV) using a mouse model.Methods and ResultsCNV was induced by laser photocoagulation in 8-week-old C57BL/6 mice. ADM mRNA expression significantly increased following treatment, peaking 4 days thereafter. The expression of ADM receptor (ADM-R) components (CRLR, RAMP2 and RAMP 3) was higher in CD31+CD45− endothelial cells (ECs) than CD31−CD45− non-ECs. Inflammatory stimulation upregulated the expression of ADM not only in cell lines but also in cells in primary cultures of the choroid/retinal pigment epithelium complex. Supernatants from TNFα-treated macrophage cell lines potentiated the proliferation of ECs and this was partially suppressed by an ADM antagonist, ADM (22–52). Intravitreous injection of ADM (22–52) or ADM neutralizing monoclonal antibody (mAb) after laser treatment significantly reduced the size of CNV compared with vehicle-treated controls (p<0.01).ConclusionsADM signaling is involved in laser-induced CNV formation, because both an ADM antagonist and ADM mAb significantly inhibited it. Suppression of ADM signaling might be a valuable alternative treatment for CNV associated with age-related macular degeneration.

Expression of adrenomedullin in human colorectal tumors and its role in cell growth and invasion in vitro and in xenograft growth in vivo

Adrenomedullin (AM) is a multifunctional peptide vasodilator that transduces its effects through calcitonin receptor-like receptor/receptor activity-modifying protein-2 and -3 (CLR/RAMP2 and CLR/RAMP3). In this study, real-time quantitative reverse transcription demonstrated a significant expression of AM mRNA in tumor samples from colorectal cancer (CRC) patients in clinical stage II, III, and IV when compared with normal colorectal tissue. AM, CLR, RAMP2, and RAMP3 proteins were immunohistochemically localized in the carcinomatous epithelial compartment of CRC tissue. Tissue microarray analysis revealed a clear increase of AM, CLR, RAMP2, and RAMP3 staining in lymph node and distant metastasis when compared with primary tumors. The human colon carcinoma cells HT-29 expressed and secreted AM into the culture medium with a significant increase under hypoxia. Treatment of HT-29 cells with synthetic AM stimulated cell proliferation and invasion in vitro. Incubation with anti-AM antibody (αAM), anti-AM receptors antibodies (αAMR), or AM antagonist AM22–52 inhibited significantly basal levels of proliferation of HT-29 cells, suggesting that AM may function as an autocrine growth factor for CRC cells. Treatment with αAM significantly suppressed the growth of HT-29 tumor xenografts in vivo. Histological examination of αAM-treated tumors showed evidence of disruption of tumor vascularity with decreased microvessel density, depletion of endothelial cells and pericytes, and increased tumor cell apoptosis. These findings highlight the potential importance of AM and its receptors in the progression of CRC and support the conclusion that αAM treatment inhibits tumor growth by suppression of angiogenesis and tumor growth, suggesting that AM may be a useful therapeutic target.

Repeated mild hypoxic exposures decrease anxiety-like behavior in the adult mouse together with an increased brain adrenomedullin gene expression

Whereas severe hypoxia is known to contribute to neuronal death and to lead to neurological disturbances, mild hypoxia can also induce beneficial effects through endogenous adaptive responses. The aim of this study was to investigate the effects of mild hypoxia (8% O2) on cognitive and emotional behavior in the adult mouse. To this end, mice were submitted to repeated mild hypoxia exposure or normoxia during 6 weeks and underwent behavioral testing during the last 3 weeks. Hypoxia decreased anxiety-like behavior in the light/dark transition test, enhanced, albeit modestly, non-spatial recognition memory, but did not alter spontaneous locomotor activity, nor spatial learning. On additional mice, whole brain adrenomedullin mRNA expression was found to be increased at D1, D25 and D41 after hypoxia initiation and vascular endothelial growth factor (VEGF) mRNA expression was increased at only on D41. This work shows that repeated mild hypoxic exposure decreases anxiety-related behavior and points out hypoxia inducible factor-1 (HIF-1) target genes, particularly adrenomedullin, as potential mediator candidate.

Effect of inhibition of the adrenomedullin gene on the growth and chemosensitivity of ovarian cancer cells

Adrenomedullin (AM), a potent vasodilator peptide, is present in various types of tumors. Here, we constructed short hairpin RNA (shRNA) in order to target the AM gene invitro using RNA interference (RNAi) technology. HO8910 ovarian cancer cells were transfected, and the effects of AM on proliferation and chemosensitivity of the cells were examined. RT-PCR, real-time PCR and western blot analysis were performed to detect the AM gene and protein expression. The MTT assay was used to observe the effect of AM on proliferation and chemosensitivity of the cells. Also, the protein levels of bcl-2 and the extracellular regulated protein kinase (ERK) were evaluated by western blot analysis. We found that silencing of the AM gene inhibited the proliferation and increased the chemosensitivity of HO8910 cells, reduced the expression of AM mRNA and protein as well as downregulated bcl-2 and p-ERK expression. We, therefore, conclude that silencing of the AM gene in HO8910 ovarian cancer cells inhibited the proliferation and increased the chemosensitivity of the cells through downregulation of ERK and bcl-2 expression. Thus, anti-AM treatment together with suppression of ERK and bcl-2 expression provides a novel research approach for ovarian cancer.

Expression of Adrenomedullin MRNA in Human Fetal Lung

Background and Aims: Adrenomedullin is a vasodilator peptide produced by endothelial and smooth muscle cells in the systemic and pulmonary circulation. It promotes angiogenesis and alveolar growth and has protective effects in the cardiovascular and respiratory systems. The role of adrenomedullin in human lung vascular development is not known. Our aim was to test the hypothesis that adrenomedullin mRNA is expressed during mid-gestation in the human fetal lung, and that adrenomedullin mRNA expression in the human fetal lung increases with advancing gestational age. Methods: Human fetal lung tissue was collected from 10 to 24 weeks of gestation following elective termination (N: 69). Gestational age was estimated using fetal foot length. Adrenomedullin gene expression was measured with quantitative RT-PCR, normalized to GAPDH. The expression of the adrenomedullin receptor: calcitonin receptor-like receptor (CRLR) and of the receptor activity modifying proteins (RAMP) 2 and 3 were also measured. Statistical analysis was performed using Spearman non-parametric correlation coefficient. Results: Adrenomedullin, CRLR, RAMP2 and RAMP3 were expressed in the mid-gestation human fetal lung. The expression of adrenomedullin, CRLR and RAMP2 increased with increasing gestational age (p< 0.05). Conversely, the expression of RAMP3 decreased with advancing gestational age. Conclusion: Adrenomedullin is expressed in the mid-gestation human fetal lung and its expression increased with increasing gestational age, suggesting a role for adrenomedullin in human lung development. The expression of RAMP3 decreased with increasing gestational age, requiring further study, we speculate that RAMP3 might regulate adrenomedullin activity in the human fetal lung.

The expression and regulation of adrenomedullin in the human endometrium: a candidate for endometrial repair.

After menstruation, the endometrium has a remarkable capacity for repair, but the factors involved remain undefined. We hypothesize adrenomedullin (AM) plays a role in this process. Premenstrually progesterone levels decline, stimulating prostaglandin (PG) synthesis, vasoconstriction, and hypoxia. This study aimed to determine 1) AM expression throughout the menstrual (M) cycle and 2) its regulation by PG and hypoxia. Human endometrial biopsies (n = 51) were collected with ethical approval and consent. AM mRNA expression was examined by quantitative RT-PCR and was found to be selectively elevated in endometrium from the menstrual (M) phase (P < 0.001). AM immunohistochemical staining was maximal in M and proliferative (P) endometrium. Culture of secretory, but not P, explants with 100 nm PGF2α or hypoxia (0.5% O2) increased AM mRNA (P < 0.05). P explants were induced to increase AM expression using in vitro progesterone withdrawal but required the presence of hypoxia (P < 0.05). Short hairpin sequences against hypoxia-inducible factor-1α (HIF-1α) inhibited AM hypoxic up-regulation but did not alter PGF2α-induced expression. The AM receptor was immunolocalized to endothelial cells in both lymphatic and blood vessels. Conditioned medium from PGF2α-treated cells increased endothelial cell proliferation and branching (P < 0.05). This was abolished by AM receptor antagonists. In conclusion, AM is elevated at the time of endometrial repair and induces both angiogenesis and lymphangiogenesis by stimulating endothelial cell proliferation and tube formation. In the human endometrium, AM expression is up-regulated by two mechanisms: a HIF-1α-mediated hypoxic induction and a HIF-1α-independent PGF2α pathway. These physiological mechanisms may provide novel therapeutic targets for disorders such as heavy menstrual bleeding.

Adrenomedullin expression and regulation in human glioblastoma, cultured human glioblastoma cell lines and pilocytic astrocytoma

Clinical and experimental studies suggest that angiogenesis is a prerequisite for solid tumour growth. Glioblastoma (GBM) and pilocytic astrocytoma (PA), both angiogenic tumours display strong contrast enhancement associated with peripheral oedema in GBM but not in PA indicating differences in vascular permeability in these two types of gliomas. Here we show that expression of adrenomedullin ( AM) mRNA is induced in GBM whereas is barely detectable in PA. In situ analysis of tumour specimens undergoing neovascularisation shows that the production of AM is specifically induced in a subset of GBM cells distinguished by their immediate proximity to necrotic foci (presumably hypoxic regions), suggesting a hypoxic induction of AM expression in GBM. Vascular endothelial growth factor ( VEGF) mRNA levels are increased in GBM and moderate in PA. Immunohistochemical study showed that cytoplasmic AM, VEGF and HIF-1α nuclear immunoreactivity were recorded in GBM located near large necrotic areas whereas they were not expressed by PA tumour cells. Interestingly, double fluorescence immunostaining demonstrated that 85% of AM immunoreactivity colocalised with VEGF. AM transduces its effects through calcitonin receptor-like receptor/receptor activity modifying protein-2 and -3 (CLR/RAMP2 and CLR/RAMP3). Real-time quantitative RT-PCR showed expression of RAMP2, RAMP3 and CLR in PA and GBM, suggesting that AM may function as an autocrine/paracrine growth factor for GBM cells. These observations strongly support the concept that tumour angiogenesis is regulated by paracrine mechanisms and identify beside VEGF, AM as a potential tumour angiogenesis factor in vivo which constitutes a potential interesting molecular target in GBM treatment.

Expression and role of adrenomedullin in renal tumors and value of its mRNA levels as prognostic factor in clear‐cell renal carcinoma

Antiangiogenic therapies are used for advanced clear-cell renal carcinomas (cRCC), but without curative possibilities, underlining the need for new therapeutic targets. Adrenomedullin (AM), a multifunctional peptide, is highly expressed in several tumors and plays an important role in angiogenesis and tumor growth through its receptors: calcitonin receptor-like receptor/receptor activity-modifying protein 2 and 3 (CLR/RAMP2 and CLR/RAMP3). In this study, real-time quantitative reverse-transcription-PCR showed AM mRNA levels were higher in cRCC and in chromophobe renal carcinomas (chRCC) than in normal renal tissue. Interestingly, AM mRNA expression in cRCC correlated strongly with VEGF-A mRNA expression. Immunohistochemically, AM, CLR and RAMP2 were localized in the carcinomatous epithelial compartment of cRCC. Interestingly, RAMP3 immunostaining was found only in the inflammatory cells that infiltrated tumors, suggesting a cross talk between tumor cells and the microenvironment. We also observed that cRCC cells BIZ and 786-O expressed and secreted AM into the culture medium. In vitro, exogenous AM treatment stimulated cell proliferation, migration and invasion, indicating the cell can respond to AM. The action of AM was specific and was mediated by the CLR/RAMP2 and CLR/RAMP3 receptors. Clinical data showed the prognostic value of AM. High AM mRNA levels were associated with an increased risk of relapse after curative nephrectomy for cRCC. These findings highlight the implication of the AM pathway in the metastatic process and the prognostic relevance of AM in cRCC and point to a potential new therapeutic target.