Expression of ETS-1 related to angiogenesis in uterine endometrium during the menstrual cycle

Dihydroartemisinin enhances VEGFR1 expression through up-regulation of ETS-1 transcription factor

Angiogenesis is required for tumor growth. Dihydroartemisinin (DHA), a the effective anti-malarial derivative of artemisinin, demonstrated potent anti-angiogenic activities that closely related to the regulation of vascular endothelial growth factor (VEGF) signaling cascade. VEGF receptor 1 (VEGFR1), a receptor in endothelial cells (ECs), coordinately regulate angiogenic activity triggered by ligand-receptor binding. Here we aimed to explore the effects of DHA on VEGFR1 expression in ECs. We found that DHA significantly increases VEGFR1 expression in human umbilical vein endothelial cells (HUVECs). In addition, DHA significantly upregulates the level of V-Ets Avian Erythroblastosis Virus E26 Oncogene Homolog 1 (ETS-1), a transcriptional factor which binds to the human VEGFR1 promoter. ChIP assay showed that DHA increases ETS-1 binding to the -52 ETS motif on the VEGFR1 promoter. Knockdown of ETS-1 by RNA interference abolished DHA-induced increase of VEGFR1 expression. Taken together, we demonstrated that DHA elevates VEGFR1 expression via up-regulation of ETS-1 transcription in HUVECs.

Sex steroids in uterine endometrial cancers

Some uterine endometrial cancers conserve estrogen dependency in advancement. However, the concept of advancement in tumor is complicated, because it involves simple growth in primary tumor and secondary spreading. The expression manner of estrogen receptor alpha exon 5 splicing variant, ER beta, progesterone receptor-A (N-terminus deletion mutant) is associated with metastatic potential in uterine endometrial cancers. Increased estrogen-related receptor alpha expression is related to tumor advancement with the loss of estrogen dependency. Steroid receptor coactivator-3 contributes to tumor progression and can be used as a treatment target for advanced uterine endometrial cancers. Estrogen responsive oncogenes, c-jun and c-Ha-ras, are not modi-fied by progestin in uterine endometrial cancer cells and are considered to be an instinct phenotype as such cancers. By contrast, metastatic potential of estrogen-dependent uterine endometrial cancers can be partially controlled by progestin via metastasis-related genes, E-cadherin/catenins, plasminogen activator inhibitor-1, vascular endothelial growth factor. Thus, sex steroids related phenomena are impress-ive in the advancement of uterine endometrial cancers.

Ets-1 is required for the activation of VEGFR3 during latent Kaposi's sarcoma-associated herpesvirus infection of endothelial cells

Kaposi's sarcoma-associated herpesvirus (KSHV), the etiologic agent of Kaposi's sarcoma (KS), is present in the predominant tumor cells of KS, the spindle cells. Spindle cells express markers of lymphatic endothelium and, interestingly, KSHV infection of blood endothelial cells reprograms them to a lymphatic endothelial cell phenotype. KSHV-induced reprogramming requires the activation of STAT3 and phosphatidylinositol 3 (PI3)/AKT through the activation of cellular receptor gp130. Importantly, KSHV-induced reprogramming is specific to endothelial cells, indicating that there are additional host genes that are differentially regulated during KSHV infection of endothelial cells that contribute to lymphatic reprogramming. We found that the transcription factor Ets-1 is highly expressed in KS spindle cells and is upregulated during KSHV infection of endothelial cells in culture. The KSHV latent vFLIP gene is sufficient to induce Ets-1 expression in an NF-κB-dependent fashion. Ets-1 is required for KSHV-induced expression of VEGFR3, a lymphatic endothelial-cell-specific receptor important for lymphangiogenesis, and Ets-1 activates the promoter of VEGFR3. Ets-1 knockdown does not alter the expression of another lymphatic-specific gene, the podoplanin gene, but does inhibit the expression of VEGFR3 in uninfected lymphatic endothelium, indicating that Ets-1 is a novel cellular regulator of VEGFR3 expression. Knockdown of Ets-1 affects the ability of KSHV-infected cells to display angiogenic phenotypes, indicating that Ets-1 plays a role in KSHV activation of endothelial cells during latent KSHV infection. Thus, Ets-1 is a novel regulator of VEGFR3 and is involved in the induction of angiogenic phenotypes by KSHV.

The role of ets factors in tumor angiogenesis

Angiogenesis is a critical component of tumor growth. A number of growth factors, including VEGF, FGF, and HGF, have been implicated as angiogenic growth factors that promote tumor angiogenesis in different types of cancer. Ets-1 is the prototypic member of the Ets transcription factor family. Ets-1 is known to be a downstream mediator of angiogenic growth factors. Expression of Ets-1 in a variety of different tumors is associated with increased angiogenesis. A role for other selected members of the Ets transcription factor family has also been shown to be important for the development of tumor angiogenesis. Because Ets factors also express a number of other important genes involved in cell growth, they contribute not only to tumor growth, but to disease progression. Targeting Ets factors in mouse tumor models through the use of dominant-negative Ets proteins or membrane permeable peptides directed at competitively inhibiting the DNA binding domain has now demonstrated the therapeutic potential of inhibiting selected Ets transcription factors to limit tumor growth and disease progression.

Expression and localization of transcription factor Ets-1 in the rat ovary during the estrous cycle and pregnancy

OBJECTIVE

To examine the expression and localization of Ets-1 in the rat ovary during the estrous cycle and pregnancy, and to investigate its effects on ovarian function.

DESIGN

Prospective, randomized study.

SETTING

Department of Physiology at Harbin Medical University.

ANIMAL(S)

Pubertal female Wistar rats.

INTERVENTION(S)

Vaginal smears were taken daily from female rats to determine the stage of the estrous cycle. Pregnancies were achieved by caging female and male rats together overnight. Ovaries were collected from both cycling and pregnant rats for tissue sectioning and RNA and protein extractions.

MAIN OUTCOME MEASURE(S)

Real-time quantitative polymerase chain reaction, Western blot, in situ hybridization, and immunohistochemistry were performed to investigate the expression and localization of Ets-1 messenger RNA (mRNA) and protein in the rat ovary during the estrous cycle and pregnancy.

RESULT(S)

During the estrous cycle, the levels of Ets-1 mRNA and protein expression increased during the follicular phase, achieving their highest measurements at proestrus and lowest at metestrus. The expression of Ets-1 mRNA and protein fluctuated during pregnancy, increasing during early pregnancy, then decreasing during mid-pregnancy, and again increasing until parturition. Ets-1 mRNA and protein were present throughout the estrous cycle and pregnancy, principally localized in follicles of various sizes and in the corpus luteum.

CONCLUSION(S)

Ets-1 may participate and play an important role in the regulation of follicular development, corpus luteum formation, maintenance, and regression.

ETS transcription factors in endocrine systems

E26 transformation-specific (ETS) transcription factors have become increasingly recognized as key regulators of differentiation, hormone responses and tumorigenesis in endocrine organs and target tissues. The ETS family is highly diverse, consisting of both transcription activators and repressors that mediate growth factor signaling and regulate gene expression through combinatorial interactions with multiple protein partners on composite DNA elements. ETS proteins have a role in the endocrine system in establishing pituitary-specific gene expression, mammary gland development and cancers of the breast, prostate and reproductive organs.

Mitogen-activated protein kinases, Erk and p38, phosphorylate and regulate Foxo1

The members of the transcription factor Foxo family regulate the expression of genes concerned with the stress response, cell cycle and gluconeogenesis. Foxo1 (FKHR) contains 15 consensus phosphorylation sites for the mitogen-activated protein kinase (MAPK) family. Therefore, we hypothesized that MAPKs could directly regulate the transcriptional activity of Foxo1 via phosphorylation. In vitro kinase assay showed that Foxo1 was phosphorylated by extracellular signal-regulated kinase (Erk) and p38 MAPK (p38) but not by c-jun NH2-terminal kinase (JNK). In NIH3T3 cells, epidermal growth factor or anisomycin increased phosphorylation of exogenous Foxo1, which was significantly inhibited by pretreatment with an MEK 1 inhibitor, PD98059, or a p38 inhibitor, SB203580. Two-dimensional phosphopeptide mapping using mutation of phosphorylation sites for MAPK revealed that the nine serine residues in Foxo1 are specifically phosphorylated by Erk and that five of the nine residues are phosphorylated by p38 in vivo. Moreover, we also found that Foxo1 interacts with Ets-1 and functions as a coactivator for Ets-1 on the fetal liver kinase (Flk)-1 promoter in bovine carotid artery endothelial cells. Mutation of the nine phosphorylation sites for Erk in Foxo1 was shown to lead to less binding and synergistic activity for Ets-1 on the Flk-1 promoter when compared with wild-type Foxo1. These results suggest that Foxo1 is specifically phosphorylated by Erk and p38, and that this phosphorylation regulates the function of Foxo1 as a coactivator for Ets-1.

The transcription factor Ets-1 is expressed in human amniochorionic membranes and is up-regulated in term and preterm premature rupture of membranes

OBJECTIVE

The major tensile strength of fetal membranes is provided by their extracellular matrix (ECM) components. The transcription factor Ets-1 is a critical mediator of ECM remodelling. The purpose of this study was to examine whether Ets-1 is expressed in human fetal membranes and whether it is implicated in premature membrane rupture.

STUDY DESIGN

Amniochorionic membranes from 52 women in the following categories were analyzed for Ets-1 expression: preterm and term premature rupture of membranes, preterm and term labor and delivery, and preterm and term cesarean sections without previous onset of labor. Ets-1 protein was localized with the use of immunohistochemistry. Ets-1 levels were determined with a histoscore.

RESULTS

Ets-1 protein was localized to the trophoblast as well as to the stromal layers. Ets-1 protein expression was up-regulated in the stroma of term and preterm prematurely ruptured membranes.

CONCLUSION

Ets-1 is expressed in human fetal membranes and its expression is up-regulated with premature rupture of membranes, suggesting a role for Ets-1 in ECM remodelling of the membranes.

Differential expression of the PEA3 subfamily of ETS transcription factors in the mouse ovary and peri-implantation uterus

The objective of the present investigation was to examine the spatio-temporal expression of three members of the ETS family of transcription factors, ERM, ER81, and PEA3, in the peri-implantation mouse uterus and in the ovary. These three factors belong to the PEA3 subfamily and are known to mediate diverse functions ranging from neuronal development to tumor progression. As transcription factors, they regulate the expression of a number of genes with various biological functions. Since several genes with known roles in the reproductive processes have been shown to be under the regulation of one of these factors, we sought to investigate the expression of ERM, ER81, and PEA3 in the mouse ovary and uterus. Quantitative RT-PCR analyses showed that ERM, ER81, and PEA3 were all expressed in the peri-implantation mouse uterus, with higher levels of expression on days 4 and 5 of pregnancy. To determine the cell type-specific expression of these factors, we employed in situ hybridization, the results of which revealed that ERM was expressed in both the epithelium and the stroma on days 4 and 5 of pregnancy. Uterine glands showed a high expression of ERM on those days. ERM was also highly expressed in the corpora lutea of the mouse ovary. Both ER81 and PEA3 were expressed at low levels in the stroma on days 4 and 5. On day 8, while ERM and PEA3 were mainly expressed in the embryo and were at low levels in the maternal decidua in a diffused pattern, ER81 was highly expressed in the vascular bed of the mesometrial deciduum. Both ER81 and PEA3 were undetectable in the mouse ovary. Collectively, these data show that ERM is implicated in the early event of implantation as well as in ovarian functions, while ER81 is involved in the establishment of the maternal vasculature for subsequent placental development. PEA3 is apparently an embryonic factor for early embryogenesis.

Sex steroid-dependent angiogenesis in uterine endometrial cancers

In general, tumors induce angiogenic factors specific to them, which leads to angiogenesis with advancement. However, angiogenesis in uterine endometrial cancers is complicated because hormone dependency in growth also modifies the angiogenic potential. Therefore, anti-angiogenic therapy for tumor dormancy in uterine endometrial cancers must be thoroughly considered. The upstream of vascular endothelial growth factor (VEGF) gene conserves estrogen-responsive elements. Progesterone primed with estrogen induces thymidine phosphorylase (TP) in uterine endometrium. Sex steroid-dependent VEGF and TP are highly expressed in cases of early stage and well-differentiated uterine endometrial cancers, and basic fibroblast growth factor (bFGF) in cases of advanced and poorly differentiated uterine endometrial cancers. A transcriptional factor for angiogenesis, ETS-1, is linked to VEGF in well-differentiated uterine endometrial cancers, and to bFGF in poorly differentiated uterine endometrial cancers. Therefore, even if dedifferentiation and angiogenic switching occur due to advancement and long-term hormone therapy, the inhibition of ETS-1 along with main angiogenic factors might be an effective strategy to suppress uterine endometrial cancers as a novel anti-angiogenic therapy.

Expression of E26 transformation specific (ETS-1) related to angiogenesis in ovarian endometriosis

ETS-1 in ovarian endometriomas was significantly positively correlated with microvessel counts (MVCs), but ETS-1 and MVC were not significantly altered during the menstrual cycle. Because ETS-1 persistently expresses in the subepithelial area of endometriotic endometrium, this might contribute to the growth of ovarian endometriomas via subepithelial angiogenesis independently of the menstrual cycle.

Oxidized phospholipids increase interleukin 8 (IL-8) synthesis by activation of the c-src/signal transducers and activators of transcription (STAT)3 pathway

Oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine (Ox-PAPC) and its component phospholipids 1-palmitoyl-2-epoxyisoprostane-sn-glycero-3-phosphorylcholine (PEIPC) and 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphorylcholine induce endothelial cells to synthesize chemotactic factors, such as interleukin 8 (IL-8). We have shown recently that Ox-PAPC-mediated induction of IL-8 transcription is independent of NF-kappaB activation, a major transcription factor utilized by cytokines and lipopolysaccharide for the induction of IL-8 transcription. In this study, we provide evidence for the role of c-src in Ox-PAPC and, specifically, PEIPC-mediated IL-8 induction. Ox-PAPC and its component phospholipids induced a rapid and transient phosphorylation of c-src Tyr418, a hallmark of c-src activation, in human aortic endothelial cells (HAEC). Ox-PAPC-mediated IL-8 protein synthesis in HAEC was inhibited by Src family kinase inhibitors, PP1 and PP2, but not by an inactive analog, PP3. Transient expression of plasmids containing C-terminal Src kinase or kinase-deficient dominant-negative c-src resulted in a 72 and 50% reduction in Ox-PAPC-induced IL-8 promoter activation in human microvascular endothelial cells, respectively. In contrast, overexpression of v-src kinase resulted in a 4-fold increase in IL-8 promoter activation, without inducing NF-kappaB promoter activation. Furthermore, treatment of HAEC with Ox-PAPC and its component PEIPC induced the activation of STAT3 by phosphorylating Tyr705, a feature of STAT3 activation. STAT3 is a known downstream effector of c-src. Ox-PAPC-induced activation of STAT3 resulted in the translocation of STAT3 from the cytoplasm of HAEC into their nuclear compartment. Transient expression of a dominant-negative STAT3beta construct in HMEC strongly inhibited IL-8 induction by Ox-PAPC. Taken together, these data demonstrate the role of the c-src kinase/STAT3 pathway in Ox-PAPC-mediated IL-8 expression in endothelial cells.

The biology of the Ets1 proto-oncogene

The Ets1 proto-oncoprotein is a member of the Ets family of transcription factors that share a unique DNA binding domain, the Ets domain. The DNA binding activity of Ets1 is controlled by kinases and transcription factors. Some transcription factors, such as AML-1, regulate Ets1 by targeting its autoinhibitory module. Others, such as Pax-5, alter Ets1 DNA binding properties. Ets1 harbors two phosphorylation sites, threonine-38 and an array of serines within the exon VII domain. Phosphorylation of threonine-38 by ERK1/2 activates Ets1, whereas phosphorylation of the exon VII domain by CaMKII or MLCK inhibits Ets1 DNA binding activity. Ets1 is expressed by numerous cell types. In haemotopoietic cells, it contributes to the regulation of cellular differentiation. In a variety of other cells, including endothelial cells, vascular smooth muscle cells and epithelial cancer cells, Ets1 promotes invasive behavior. Regulation of MMP1, MMP3, MMP9 and uPA as well as of VEGF and VEGF receptor gene expression has been ascribed to Ets1. In tumors, Ets1 expression is indicative of poorer prognosis.