Endocrine Gland-derived Vascular Endothelial Growth Research Articles

Endocrine gland‐derived vascular endothelial growth factor (EG‐VEGF) expression in colorectal cancer

Vascular endothelial growth factor (VEGF) is known as an important factor in the growth and metastasis of cancer cells. In 2001, a novel angiogenesis factor, endocrine gland-derived vascular endothelial growth factor (EG-VEGF), was cloned. In this study, we investigated the expression of EG-VEGF in colorectal cancer, the relationship between its expression and clinicopathological factors, and the in vitro activity of EG-VEGF transfectants. We determined expression levels of EG-VEGF in 113 advanced colorectal cancers resected in our hospital by quantitative PCR, and compared the expression levels and clinicopathological findings by multivariate analyses. The expression of EG-VEGF mRNA was positive in 31 cancers and negative in 82 cancers. We found that compared with the negative expression of the EG-VEGF gene, its positive expression was more frequently associated with hematogenous metastasis, and was associated with a poorer survival rate. In addition, EG-VEGF transfectants showed a higher degree of in vitro tubular formation than control cells. We speculate that, in colorectal cancers, the EG-VEGF gene functions as an important factor in angiogenesis in primary and metastatic lesions, and consider that it is useful as a novel prognostic factor. EG-VEGF molecule-targeted therapy has the potential for improving survival rates.

Expression and localization of endocrine gland-derived vascular endothelial growth factor (EG-VEGF) in human pancreas and pancreatic adenocarcinoma

Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) was recently identified as the first tissue-specific angiogenic molecule. EG-VEGF (the gene product of PROK-1) appears to be expressed exclusively in steroid-producing organs such as the ovary, testis, adrenals and placenta. Since the human pancreatic cells retain steroidogenic activity, in the present study we ascertained whether this angiogenic factor is expressed in normal pancreas and pancreatic adenocarcinoma. Tissue samples from normal males ( n = 5), normal females ( n = 5) and from surgically resected adenocarcinomas ( n = 2) were processed for RT-PCR and immunohistochemical studies. Results from semi-quantitative analysis by RT-PCR suggest a distinct expression level for EG-VEGF in the different tissue samples. The relative amount of EG-VEGF mRNA in pancreas was more abundant in female adenocarcinoma (0.89) followed by male adenocarcinoma (0.71), than normal female (0.64) and normal male (0.38). The expression of mRNA for EG-VEGF in normal tissue was significantly higher in females than in males. All samples examined showed specific immunostaining for EG-VEGF. In male preparations, the positive labeling was localized predominantly within the pancreatic islets while in female preparations the main staining was detected towards the exocrine portion. Specific immunolabeling was also observed in endothelial cells of pancreatic blood vessels. Our data provide evidence that the human pancreas expresses the EG-VEGF, a highly specific mitogen which regulates proliferation and differentiation of the vascular endothelium. The significance of this finding could be interpreted as either, EG-VEGF is not exclusive of endocrine organs, or the pancreas should be considered as a functional steroidogenic tissue. The extent of the expression of EG-VEGF appears to have a dimorphic pattern in normal and tumoral pancreatic tissue.

Placental Expression of EG-VEGF and its Receptors PKR1 (Prokineticin Receptor-1) and PKR2 Throughout Mouse Gestation

Compelling evidence indicates that vascular endothelial growth factor (VEGF) is an important mediator of placental angiogenesis and appears to be disregulated in pre-eclampsia (PE). Recently, we characterised the expression of EG-VEGF (endocrine gland-derived vascular endothelial growth factor), also known as prokineticin 1 (PK1) in human placenta during the first trimester of pregnancy and showed that this factor is likely to play an important role in human placentation. However, because it is impossible to prospectively study placentation in humans, it has been impossible to further characterise EG-VEGF expression throughout complete gestation and especially at critical gestational ages for PE development. In the present study, we used mouse placenta to further characterise EG-VEGF expression throughout gestation. We investigated the pattern of expression of EG-VEGF and its receptors, PKR1 and PKR2 at the mRNA and protein levels. Our results show that EG-VEGF and VEGF exhibit different patterns of expression and different localisations in the mouse placenta. EG-VEGF was mainly localised in the labyrinth whereas VEGF was mainly present in glycogen and giant cells. EG-VEGF mRNA and protein levels were highest before 10.5 days post coitus (dpc) whereas those of VEGF showed stable expression throughout gestation. PKR1 protein was localised to the labyrinth layer and showed the same pattern of expression as EG-VEGF whereas PKR2 expression was maintained over 10.5 dpc with both trophoblastic and endothelial cell localisations. Altogether these findings suggest that EG-VEGF may have a direct effect on both endothelial and trophoblastic cells and is likely to play an important role in mouse placentation.

Expression Pattern of Prokineticin 1 and Its Receptors in Bovine Ovaries During the Estrous Cycle: Involvement in Corpus Luteum Regression and Follicular Atresia

Prokineticin 1 (PROK1), also termed endocrine gland-derived vascular endothelial growth factor (endocrine gland-derived VEGF), is a newly identified protein assigned with diverse biologic functions. It binds two homologous G protein-coupled receptors, PROKR1 and PROKR2. To better understand the roles of PROK1 and its receptors in ovarian function, their expression was determined in follicles and corpora lutea (CLs) at different developmental stages. PROK1 mRNA levels were low at early luteal stage and midluteal stage, but increased sharply during natural or induced luteolysis. High PROK1 mRNA levels also were found in atretic follicles. This profile of PROK1 expression was opposite to that of the well-established angiogenic factor VEGF. Of the two receptor-type expressions, PROKR1 but not PROKR2 was correlated positively with its ligand. Immunohistochemical staining revealed that PROK1 was located mainly within the muscular layer of arterioles, and during regression it also was localized to macrophages and steroidogenic cells. The expression pattern of ITGB2 mRNA, a leukocyte cell marker, overlapped that of PROK1, thus suggesting that leukocyte infiltration may explain the elevated expression of PROK1 in atretic follicles and regressing CL. Indeed, flow cytometry analyses showed that nearly all beta-2 integrin chain (ITGB2)-positive cells also were stained with anti-PROK1 and that significantly more ITGB2/PROK1 double-stained cells were present in degenerating follicles and CL. Furthermore, when challenged in vitro with PROK1, adherent, mononuclear cell numbers and TNF levels were elevated, indicating that PROK1 triggers monocyte activation. Together, these data suggest that PROK1, acting via PROKR1, may be involved in the recruitment of monocytes to regressing CL and atretic follicles and their consequent activation therein.

ENDOCRINE GLAND-VASCULAR ENDOTHELIAL GROWTH FACTOR (EG-VEGF) IN NORMAL PANCREAS AND PANCREATIC ADENOCARCINOMA

Introduction: Endocrine gland-derived vascular endothelial growth factor (EG-VEGF), and the mammalian homologue of Bombina variegata peptide 8 (Bv8), are two highly related endothelial cell mitogens and chemoattractant factors with restricted expression profiles. Human EG-VEGF messenger RNA is expressed by steroid producing cells in the adrenal gland, placenta, testis and ovary. Consistent with such expression pattern, the human EG-VEGF gene promoter has a potential binding site for steroidogenic factor SF-1, a pivotal element for steroidogenic-specific transcription. The occurrence of SF-1 in the endothelial cells of the blood vessels together with the steroidogenic properties of the pancreas are two characteristics that might account for the possibility that EG-VEGF could be the regulatory factor in angiogenesis in this tissue. The aim of this study was to investigate the expression and localization of the EG-VEGF in normal human pancreas and pancreatic adenocarcinoma. Methods: Total RNA was extracted from male (5) and female (5) samples, obtained from the organs donors program and samples (2) of surgically resected adenocarcinoma. The relative expression of pancreatic EG-VEGF was assessed by RT-PCR analysis using specific primers. Anti-EG-VEGF goat polyclonal Ig-G (sc-30343 Santa-Cruz) antibodies were used to determine the cellular localization of the protein in pancreatic tissue. Results: By RT-PCR, specific amplicons for EG-VEGF were detected in both male and female samples, though a differential expression was observed. According to densitometric analysis, the relative abundance of mRNAs was: female adenocarcinoma 0.89> female normal pancreas 0.64> male adenocarcinoma 0.71> male normal pancreas 0.38. Immunohistochemical studies also showed a different staining. In male samples, the signal was localized preferentially in the pancreatic islets while in female samples, the main staining was observed towards the exocrine portion. In tumoral samples, the specific staining showed a diffuse localization pattern. Conclusion: The expression of EG-VEGF/PROK1 gene in pancreas resembles to that reported for other endocrine tissues, such as the ovary and adrenals and adds evidence to the linkage of steroids with pancreatic physiology. These results also demonstrate a differential expression between normal and tumoral tissues. The human pancreas expresses EG-VEGF, a highly specific mitogen, which regulates proliferation and differentiation of the vascular endothelium in a tissue-specific manner.

Impaired Nociception and Inflammatory Pain Sensation in Mice Lacking the Prokineticin Receptor PKR1: Focus on Interaction between PKR1 and the Capsaicin Receptor TRPV1 in Pain Behavior

Bv8, prokineticin-1 or EG-VEGF (endocrine gland-derived vascular endothelial growth factor), and prokineticin-2, are naturally occurring peptide agonists of two G-protein-coupled receptors (GPCRs), prokineticin receptor 1 (PKR1) and PKR2. PKRs are expressed in neurons in the CNS and peripheral nervous system and many dorsal root ganglion (DRG) cells expressing PKRs also express transient receptor potential vanilloid receptor-1 (TRPV1). Mice lacking the pkr1 gene were generated to explore the role of the PKR1 receptor in nociceptive signaling and in nociceptor sensitization. When compared with wild-type littermates, mice lacking the pkr1 gene showed impaired responsiveness to noxious heat, mechanical stimuli, capsaicin, and protons. In wild-type mice, activation of PKRs by the PKR agonist Bv8 caused hyperalgesia and sensitized to the actions of capsaicin. pkr1-null mice exhibited impaired responses to Bv8 but showed normal hyperalgesic responses to bradykinin and PGE2 (prostaglandin E2). Conversely, trpv1-null mice showed a reduced pronociceptive response to Bv8. Additionally, pkr1-null mice showed diminished thermal hyperalgesia after acute inflammation elicited by mustard oil and reduced pain behavior after chronic inflammation produced by complete Freund's adjuvant. The number of neurons that responded with a [Ca2+]i increase to Bv8 exposure was five times lower in pkr1-null DRG cultures than in wild-type cultures. Furthermore, Bv8-responsive neurons from pkr1-null mice showed a significant reduction in the [Ca2+]i response to capsaicin. These findings indicate a modulatory role of PKR1 in acute nociception and inflammatory pain and disclose a pharmacological interaction between PKR1 and TRPV1 in nociceptor activation and sensitization.

Expression and Oxygen Regulation of Endocrine Gland-Derived Vascular Endothelial Growth Factor/Prokineticin-1 and Its Receptors in Human Placenta during Early Pregnancy

Angiogenesis is a key process of dynamic tissue remodeling occurring during placentation. Compelling evidence indicates that vascular endothelial growth factor (VEGF) is an important mediator of placental angiogenesis and appears to be deregulated in preeclampsia. Recently a new angiogenic factor, endocrine gland-derived VEGF (EG-VEGF), also known as prokineticin 1 (PK1), has been identified, and its expression was shown to be restricted to endocrine glands, including the placenta. In this study we investigated the pattern of expression of EG-VEGF, its related factor Bv8/PK2, and their common receptors, PKR1 and PKR2, in human placenta during the first trimester of pregnancy. We also examined EG-VEGF and PKR1 regulation by oxygen tension in isolated trophoblast cells (TCs). Our results show that EG-VEGF, but not Bv8/PK2, is expressed in human placenta. EG-VEGF is mainly localized to the syncytiotrophoblast layer with the highest expression detected between the 8th and 10th wk of gestation. EG-VEGF expression within placental villi is different from that of VEGF, which is mainly localized in the cytotrophoblast and extravillous trophoblast cells. In TCs, PKR1 mRNA is about 80 times more abundant than PKR2 mRNA. Both EG-VEGF and PKR1 mRNAs appear to be regulated by hypoxia. These findings suggest that EG-VEGF has a direct effect on TCs via its receptor PKR1 and is likely to play an important role in human placentation. The expression pattern of EG-VEGF, its regulation by oxygen tension, and its complementary localization to that of VEGF suggest that this new factor might also be deregulated in preeclampsia.

Endocrine Gland-Derived Vascular Endothelial Growth Factor Is Expressed in Human Peri-implantation Endometrium, But Not in Endometrial Carcinoma

Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) is a newly identified angiogenic and permeability-enhancing factor, predominantly expressed in steroidogenic tissues. Recently, we found that EG-VEGF is also expressed in the normal peri-implantation endometrial samples from patients of reproductive ages (80%). Immunohistochemistry analysis showed that EG-VEGF is predominantly expressed in the glandular epithelial cells and its expression is dynamic during the menstrual cycle with a peak expression at the mid-luteal phase. We also found that EG-VEGF transcripts are up-regulated in all the peri-implantation endometrial samples from the patients after the ovulating dose of human chorionic gonadotropin in gonadotropin-stimulated cycles and patients receiving hormone replacement therapy. In in vitro endometrial cell culture, EG-VEGF mRNA was detected in endometrial cells only in the presence of steroids, suggesting that EG-VEGF expression is highly dependent on the steroid hormones. Subsequent expression analyses on the EG-VEGF receptors showed that hPK-R1 and hPK-R2 are differentially expressed in human endometrium, but show no significant correlation with the hormonal treatments. On the other hand, EG-VEGF transcript was rarely detected in the endometrial samples from the postmenopausal patients and patients with endometrial carcinoma. It may imply that EG-VEGF may only play a role in vascular function of peri-implantation endometrium, but is unlikely to be associated with the etiology of endometrial cancer development.

Unique expression and regulatory mechanisms of EG-VEGF/prokineticin-1 and its receptors in the corpus luteum

Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) or Prokineticin-1 (PK-1) is a novel cysteine-rich protein that belongs to the AVIT protein family. EG-VEGF/PK-1, described as selective angiogenic mitogen, is widely expressed in different tissues including steroidogenic endocrine glands. This review summarizes the expression and functions of EG-VEGF/PK-1 in corpus luteum (CL)-derived cells: endothelial and steroidogenic cell types. EG-VEGF/PK-1 mRNA is expressed by luteal steroidogenic cells of human, rat and bovine ovaries, but was absent from the luteal Endothelial cells CLEC. Luteal EC expressed high levels of both PK-receptors PK-R1 and PK-R2 - the two G protein-coupled PK-1 receptors. Interestingly, expression of EG-VEGF/PK-1 and VEGF were inversely regulated in human and bovine luteinized granulosa cells. EG-VEGF/PK-1 elevated [3H]-thymidine incorporation, MAPK activation and c-jun/fos mRNA expression and enhanced LEC proliferation. EG-VEGF/PK-1 also inhibited serum starvation-induced apoptosis in these cells. Stress conditions such as serum withdrawal, TNFalpha and chemical hypoxia markedly increase PK-R2 expression, whereas mRNA levels of PK-R1 remain unchanged, implying that the anti-apoptotic effect of PK-1 on LEC may be mediated via PK-R2. Besides its direct mitogenic and anti-apoptotic effects, EG-VEGF/PK-1 elevated VEGF mRNA expression in bovine luteal steroidogenic cells, which possesses only PK-R1. Together, these findings suggest an important role for PK-1 in luteal function by acting as a mitogen and survival factor in LEC. Nevertheless, the inverse regulation of EG-VEGF/PK1 and VEGF mRNA expression by ovarian cells and the distribution of its receptors may suggest that in addition to its angiogenic effects, EG-VEGF/PK-1 may also play other roles in ovary.

Prokineticins (Endocrine Gland-Derived Vascular Endothelial Growth Factor and BV8) in the Bovine Ovary: Expression and Role as Mitogens and Survival Factors for Corpus Luteum-Derived Endothelial Cells

A highly vascular endocrine gland, the corpus luteum (CL) is an excellent model for the study of angiogenic factors. Prokineticins (PK-1 and -2), also termed endocrine-gland-derived vascular endothelial growth factor (VEGF) and BV8 are newly identified proteins described as selective angiogenic mitogens. We previously identified PK binding sites, two closely homologous G protein-coupled receptors (PK-R1 and PK-R2) in human and bovine ovarian cells, but their function remained unknown. In this study we examined the presence and effects of PK in CL-derived endothelial and steroidogenic cell types (LEC and LSC, respectively). PK-1 mRNA was identified in CL and follicles by real-time PCR, using primers specific for the bovine PK-1 sequence (retrieved from Bos taurus whole genome shotgun database). PK were potent angiogenic mitogens for LEC; they enhanced cell proliferation, elevated [3H]thymidine incorporation, MAPK activation, and c-jun/fos mRNA expression. The effects of PK proteins on cell survival were examined by nuclear morphology (4',6-diamidino-2-phenylindole dihydrochloride staining), measurement of DNA fragmentation (terminal dUTP nucleotide end labeling assay), and caspase-3 cleavage. Results obtained by these techniques demonstrated that PK protected LEC from serum starvation-induced apoptosis. Stress conditions such as serum withdrawal, TNF-alpha, and hypoxia markedly increased PK-R2 expression, whereas mRNA levels of PK-R1 remained unchanged. These suggest that the antiapoptotic effect of PK-1 on LEC may be mediated via PK-R2. PK-1 increased VEGF mRNA expression by LSC, implying that it could also indirectly, via VEGF, affect luteal angiogenesis. Together, these findings suggest an important role for PK-1 in luteal function by acting as a mitogen and survival factor in LEC.

PK1/EG-VEGF induces monocyte differentiation and activation

Macrophages exist as sentinels in innate immune response and react by expressing proinflammatory cytokines and up-regulating antigen-presenting and costimulatory molecules. We report a novel function for prokineticin-1 (PK1)/endocrine gland-derived vascular endothelial growth factor. Screening of murine tissue sections and cells for specific binding site leads to the identification of macrophages as an in vivo cellular target for PK1. We demonstrate PK1 induces differentiation of murine and human bone marrow cells into the monocyte/macrophage lineage. Human peripheral blood monocytes respond to PK1 by morphological changes and down-regulation of B7-1, CD14, CC chemokine receptor 5, and CXC chemokine receptor 4. Monocytes treated with PK1 have elevated interleukin (IL)-12 and tumor necrosis factor alpha and down-regulated IL-10 production in response to lipopolysaccharide. PK1 induces a distinct monocyte-derived cell population, which is primed for release of proinflammatory cytokines that favor a T helper cell type 1 response.

Bv8 and endocrine gland-derived vascular endothelial growth factor stimulate hematopoiesis and hematopoietic cell mobilization

Bv8 and endocrine-gland-derived VEGF (EG-VEGF), or prokineticins, are two highly related, secreted proteins that we previously described as selective angiogenic mitogens. Here we describe the expression and functional characterization of Bv8 in peripheral blood cells, notably monocytes, neutrophils, and dendritic cells, and in the bone marrow. In human and mouse, the two Bv8 G protein-coupled receptors are expressed in hematopoietic stem cells and specific mature blood cells, including lymphocytes. Bv8 is highly expressed by neutrophils at sites of inflammation and can stimulate migration of monocytes, in a pertussis toxin-sensitive manner. Bv8, or EG-VEGF that shares the same receptors, increased numbers of colony-forming units granulocytic and monocytic in cultures of human or mouse hematopoietic stem cells. Systemic in vivo exposure to Bv8 or EG-VEGF resulted in significant increases in total leukocyte, neutrophil, and monocyte counts. Additionally, adenovirus (Av)Bv8 or AvEG-VEGF delivered just before 5-fluorouracil injury promoted the survival of hematopoietic cells and enhanced progenitor mobilization. In conclusion, Bv8 can promote survival and differentiation of the granulocytic and monocytic lineages. Bv8 potentially modulates growth, survival, and function of cells of the innate and adaptive immune systems, possibly through autocrine or paracrine signaling mechanisms.

Human endocrine gland-derived vascular endothelial growth factor: expression early in development and in Leydig cell tumors suggests roles in normal and pathological testis angiogenesis.

Angiogenesis is essential for tumor growth and metastasis. A new human angiogenic mitogen, endocrine gland-derived vascular endothelial growth factor (EG-VEGF), has been recently identified; its expression pattern is restricted to endocrine glands, with the highest expression in testis. We used in situ hybridization and newly generated monoclonal antibodies to investigate the expression of EG-VEGF in normal human prenatal and adult testis and in 48 human testicular tumors of different subtypes. We found that EG-VEGF was expressed from 14 wk until birth in human fetal testis. In the adult testis, EG-VEGF was strongly expressed only in Leydig cells. In testicular tumors, EG-VEGF was expressed specifically in Leydig cell tumors, whereas germ cell-derived neoplasms, including carcinoma in situ, seminoma, and nonseminomatous germ cell tumors, were negative for this antigen. In contrast, VEGF, another powerful angiogenic factor, was expressed in seminoma, but very weakly in Leydig cell tumors. Interestingly, we found that Leydig cell tumors presented vessel surface density 3.2-fold higher than seminoma. These findings argue that human EG-VEGF may play a role in angiogenesis both during the early endocrine development of testis and in the adult testis as well as in Leydig cell tumor growth.

Expression and regulation of the prokineticins (endocrine gland-derived vascular endothelial growth factor and Bv8) and their receptors in the human endometrium across the menstrual cycle.

This study investigated the possible role of the newly discovered endocrine gland-derived vascular endothelial growth factors and their cognate receptors in the human endometrium during the menstrual cycle. Endocrine gland-derived vascular endothelial growth factors are also known as prokineticin (PK) 1 and PK2 and their receptors as PKR1 and PKR2. Expression of PK1 was elevated in the secretory compared with the proliferative phase of the menstrual cycle (P < 0.05). There was no temporal variation in expression of PK2, PKR1, or PKR2. PK1 and PK2 and their receptors were localized to multiple cellular compartments, including glandular epithelial, stromal, and endothelial cells in the endometrium and endothelial and smooth muscle cells in the myometrium. The elevation in PK1 expression in the secretory phase of the menstrual cycle indicated potential regulation of PK1 by progesterone. To investigate this, endometrial tissue was treated with 1 microM (micromol/liter(-1)) progesterone for 24 h, and PK1 expression was assessed by quantitative RT-PCR. Treatment with 1 microM ( micromol/liter(-1)) progesterone resulted in 2.91 +/- 0.75-fold elevation in PK1 expression, compared with controls (P < 0.05). These data identify a paracrine role for the PKs and their receptors in endometrial vascular function.

Mouse endocrine gland-derived vascular endothelial growth factor: a distinct expression pattern from its human ortholog suggests different roles as a regulator of organ-specific angiogenesis.

We recently described human endocrine gland-derived vascular endothelial growth factor (EG-VEGF) as an endothelial cell mitogen with a novel selective activity and an expression pattern essentially limited to steroidogenic glands. Herein we present the identification and characterization of the mouse ortholog. The mouse cDNA and predicted amino acid sequences are, respectively, 86% and 88% identical with the human. Surprisingly, the mouse EG-VEGF transcript is predominantly expressed in liver and kidney. A comparison of human and mouse EG-VEGF promoter sequences revealed a potential binding site for NR5A1, which is known to be a pivotal element for steroidogenic-specific transcription, in the human but not mouse promoter. In situ hybridization studies localized expression of mouse EG-VEGF mRNA to hepatocytes and renal tubule cells. Interestingly, capillary endothelial cells in these sites share several common structural features with those found in steroidogenic glands. Within liver and kidney, EG-VEGF receptor expression was largely restricted to endothelial cells. Mouse EG-VEGF promoted proliferation and survival of endothelial cells. We propose that mouse EG-VEGF, like human EG-VEGF, plays a role in regulating the phenotype and growth properties of endothelial cells within distinct capillary beds.

Isolation and identification of EG-VEGF/prokineticins as cognate ligands for two orphan G-protein-coupled receptors

Endocrine gland-derived vascular endothelial growth factor (EG-VEGF, identical to prokineticin 1) is a novel peptide recently identified as a selective mitogen for endocrine gland endothelial cells. The present study demonstrates that EG-VEGF/prokineticin 1 and a peptide closely related to EG-VEGF, prokineticin 2, are cognate ligands of two orphan G-protein-coupled receptors designated ZAQ (=EG-VEGF/PK-R1) and I5E (=EG-VEGF/PK-R2). EG-VEGF/prokineticin 1 and prokineticin 2 induced a transient increase in intracellular calcium ion concentration ([Ca 2+] i) with nanomolar potency in Chinese hamster ovary (CHO) cells expressing EG-VEGF/PK-R1 and -R2 and bind to these cells with high affinity and with different receptor selectivity. EG-VEGF/prokineticins provoke rapid phosphorylation of p44/42 MAP kinase and DNA synthesis in the bovine adrenal capillary endothelial cells (BACE). The mRNAs of both EG-VEGF/PK-R1 and -R2 were expressed in BACE. The identification of the receptors for EG-VEGF/prokineticins may provide a novel molecular basis for the regulation of angiogenesis in endocrine glands.

Characterization of Endocrine Gland-derived Vascular Endothelial Growth Factor Signaling in Adrenal Cortex Capillary Endothelial Cells

Endocrine gland-derived vascular endothelial growth factor (EG-VEGF) has been recently identified as a mitogen specific for the endothelium of steroidogenic glands. Here we report a characterization of the signal transduction of EG-VEGF in a responsive cell type, bovine adrenal cortex-derived endothelial (ACE) cells. EG-VEGF led to a time- and dose-dependent phosphorylation of p44/42 MAPK. This effect was blocked by pretreatment with pertussis toxin, suggesting that G alpha(i) plays an important role in mediating EG-VEGF-induced activation of MAPK signaling. The inhibitor of p44/42 MAPK phosphorylation PD 98059 resulted in suppression of both proliferation and migration in response to EG-VEGF. EG-VEGF also increased the phosphorylation of Akt in a phosphatidylinositol 3-kinase-dependent manner. Consistent with such an effect, EG-VEGF was a potent survival factor for ACE cells. We also identified endothelial nitric-oxide synthase as one of the downstream targets of Akt activation. Phosphorylation of endothelial nitric-oxide synthase in ACE cells was stimulated by EG-VEGF with a time course correlated to the Akt phosphorylation. Our data demonstrate that EG-VEGF, possibly through binding to a G-protein coupled receptor, results in the activation of MAPK p44/42 and phosphatidylinositol 3-kinase signaling pathways, leading to proliferation, migration, and survival of responsive endothelial cells.