Seminal plasma promotes the expression of tumorigenic and angiogenic genes in cervical adenocarcinoma cells via the E-series prostanoid 4 receptor

Prostaglandin Pathways: Opportunities for Cancer Prevention and Therapy

Because of profound effects observed in carcinogenesis, prostaglandins (PGs), prostaglandin-endoperoxide synthases, and PG receptors are implicated in cancer development and progression. Understanding the molecular mechanisms of PG actions has potential clinical relevance for cancer prevention and therapy. This review focuses on the current status of PG signaling pathways in modulating cancer progression and aims to provide insights into the mechanistic actions of PGs and their receptors in influencing tumor progression. We also examine several small molecules identified as having anticancer activity that target prostaglandin receptors. The literature suggests that targeting PG pathways could provide opportunities for cancer prevention and therapy.

Isookanin Inhibits PGE2-Mediated Angiogenesis by Inducing Cell Arrest through Inhibiting the Phosphorylation of ERK1/2 and CREB in HMEC-1 Cells

Inflammation is increasingly recognized as a critical mediator of angiogenesis, and unregulated angiogenic responses often involve human diseases. The importance of regulating angiogenesis in inflammatory diseases has been demonstrated through some successful cases of anti-angiogenesis therapies in related diseases, including arthritis, but it has been reported that some synthetic types of antiangiogenic drugs have potential side effects. In recent years, the importance of finding alternative strategies for regulating angiogenesis has begun to attract the attention of researchers. Therefore, identification of natural ingredients used to prevent or treat angiogenesis-related diseases will play a greater role. Isookanin is a phenolic flavonoid presented in Bidens extract, and it has been reported that isookanin possesses some biological properties, including antioxidative and anti-inflammatory effects, anti-diabetic properties, and an ability to inhibit α-amylase. However, its antiangiogenic effects and mechanism thereof have not been studied yet. In this study, our results indicate that isookanin has an effective inhibitory effect on the angiogenic properties of microvascular endothelial cells. Isookanin shows inhibitory effects in multiple stages of PGE₂-induced angiogenesis, including the growth, proliferation, migration, and tube formation of microvascular endothelial cells. In addition, isookanin induces cell cycle arrest in S phase, which is also the reason for subsequent inhibition of cell proliferation. The mechanism of inhibiting angiogenesis by isookanin is related to the inhibition of PGE₂-mediated ERK1/2 and CREB phosphorylation. These findings make isookanin a potential candidate for the treatment of angiogenesis-related diseases.

The Female Response to Seminal Fluid

Seminal fluid is often assumed to have just one function in mammalian reproduction, delivering sperm to fertilize oocytes. But seminal fluid also transmits signaling agents that interact with female reproductive tissues to facilitate conception and .pregnancy. Upon seminal fluid contact, female tissues initiate a controlled inflammatory response that affects several aspects of reproductive function to ultimately maximize the chances of a male producing healthy offspring. This effect is best characterized in mice, where the female response involves several steps. Initially, seminal fluid factors cause leukocytes to infiltrate the female reproductive tract, and to selectively target and eliminate excess sperm. Other signals stimulate ovulation, induce an altered transcriptional program in female tract tissues that modulates embryo developmental programming, and initiate immune adaptations to promote receptivity to implantation and placental development. A key result is expansion of the pool of regulatory T cells that assist implantation by suppressing inflammation, mediating tolerance to male transplantation antigens, and promoting uterine vascular adaptation and placental development. Principal signaling agents in seminal fluid include prostaglandins and transforming growth factor-β. The balance of male signals affects the nature of the female response, providing a mechanism of ‟cryptic female choiceˮ that influences female reproductive investment. Male-female seminal fluid signaling is evident in all mammalian species investigated including human, and effects of seminal fluid in invertebrates indicate evolutionarily conserved mechanisms. Understanding the female response to seminal fluid will shed new light on infertility and pregnancy disorders and is critical to defining how events at conception influence offspring health.

Extracellular vesicles in human semen modulate antigen-presenting cell function and decrease downstream antiviral T cell responses

Human semen contains trillions of extracellular vesicles (SEV) similar in size to sexually transmitted viruses and loaded with potentially bioactive miRNAs, proteins and lipids. SEV were shown to inhibit HIV and Zika virus infectivity, but whether SEV are able also to affect subsequent immune responses is unknown. We found that SEV efficiently bound to and entered antigen-presenting cells (APC) and thus we set out to further dissect the impact of SEV on APC function and the impact on downstream T cell responses. In an APC–T cell co-culture system, SEV exposure to APC alone markedly reduced antigen-specific cytokine production, degranulation and cytotoxicity by antigen-specific memory CD8+ T cells. In contrast, inhibition of CD4+ T cell responses required both APC and T cell exposure to SEV. Surprisingly, SEV did not alter MHC or co-stimulatory receptor expression on APCs, but caused APCs to upregulate indoleamine 2,3 deoxygenase, an enzyme known to indirectly inhibit T cells. Thus, SEV reduce the ability of APCs to activate T cells. We propose here that these immune-inhibitory properties of SEV may be intended to prevent immune responses against semen-derived antigens, but can be hi-jacked by genitally acquired viral infections to compromise adaptive cellular immunity.

The Formation and Therapeutic Update of Tumor-Associated Macrophages in Cervical Cancer

Both clinicopathological and experimental studies have suggested that tumor-associated macrophages (TAMs) play a key role in cervical cancer progression and are associated with poor prognosis in the respects of tumor cell proliferation, invasion, angiogenesis, and immunosuppression. Therefore, having a clear understanding of TAMs is essential in treating this disease. In this review, we will discuss the origins and categories of macrophages, the molecules responsible for forming and reeducating TAMs in cervical cancer (CC), the biomarkers of macrophages and the therapy development targeting TAMs in CC research.

Zinc reduces epithelial barrier compromise induced by human seminal plasma

Human semen has the potential to modulate the epithelial mucosal tissues it contacts, as seminal plasma (SP) is recognized to contain both pro- and anti-barrier components, yet its effects on epithelial barrier function are largely unknown. We addressed the role of human SP when exposed to the basal-lateral epithelial surface, a situation that would occur clinically with prior mechanical or disease-related injury of the human epithelial mucosal cell layers in contact with semen. The action of SP on claudins-2, -4, -5, and -7 expression, as well as on a target epithelium whose basolateral surface has been made accessible to SP, showed upregulation of claudins-4 and -5 in CACO-2 human epithelial cell layers, despite broad variance in SP-induced modulation of transepithelial electrical resistance and mannitol permeability. Upregulation of claudin-2 by SP also exhibited such variance by SP sample. We characterize individual effects on CACO-2 barrier function of nine factors known to be present abundantly in seminal plasma (zinc, EGF, citrate, spermine, fructose, urea, TGF, histone, inflammatory cytokines) to establish that zinc, spermine and fructose had significant potential to raise CACO-2 transepithelial resistance, whereas inflammatory cytokines and EGF decreased this measure of barrier function. The role of zinc as a dominant factor in determining higher levels of transepithelial resistance and lower levels of paracellular leak were confirmed by zinc chelation and exogenous zinc addition. As expected, SP presentation to the basolateral cell surface also caused a very dramatic yet transient elevation of pErk levels. Results suggest that increased zinc content in SP can compete against the barrier-compromising effect of negative modulators in SP when SP gains access to that epithelium's basolateral surface. Prophylactic elevation of zinc in an epithelial cell layer prior to contact by SP may help to protect an epithelial barrier from invasion by SP-containing STD microbial pathogens such as HPV or HIV.

Seminal Fluid-Mediated Inflammation in Physiology and Pathology of the Female Reproductive Tract

Inflammation is a multifaceted process involving a host of resident and recruited immune cells that eliminate the insult or injury and initiate tissue repair. In the female reproductive tract (FMRT), inflammation-mediated alterations in epithelial, vascular, and immune functions are important components of complex physiological processes and many local and systemic pathologies. It is well established that intracoital and postcoital function of seminal fluid (SF) goes beyond nutritive support for the spermatozoa cells. SF, in particular, the inflammatory bioactive lipids, and prostaglandins present in vast quantities in SF, have a role in localized immune modulation and regulation of pathways that can exacerbate inflammation in the FMRT. In sexually active women SF-mediated inflammation has been implicated in physiologic processes such as ovulation, implantation, and parturition while also enhancing tumorigenesis and susceptibility to infection. This review highlights the molecular mechanism by which SF regulates inflammatory pathways in the FMRT and how alterations in these pathways contribute to physiology and pathology of the female reproductive function. In addition, based on findings from TaqMan® 96-Well Plate Arrays, on neoplastic cervical cells treated with SF, we discuss new findings on the role of SF as a potent driver of inflammatory and tumorigenic pathways in the cervix.

Seminal Fluid Signalling in the Female Reproductive Tract: Implications for Reproductive Success and Offspring Health

Carriage of sperm is not the only function of seminal fluid in mammals. Studies in mice show that at conception, seminal fluid interacts with the female reproductive tract to induce responses which influence whether or not pregnancy will occur, and to set in train effects that help shape subsequent fetal development. In particular, seminal fluid initiates female immune adaptation processes required to tolerate male transplantation antigens present in seminal fluid and inherited by the conceptus. A tolerogenic immune environment to facilitate pregnancy depends on regulatory T cells (Treg cells), which recognise male antigens and function to suppress inflammation and immune rejection responses. The female response to seminal fluid stimulates the generation of Treg cells that protect the conceptus from inflammatory damage, to support implantation and placental development. Seminal fluid also elicits molecular and cellular changes in the oviduct and endometrium that directly promote embryo development and implantation competence. The plasma fraction of seminal fluid plays a key role in this process with soluble factors, including TGFB, prostaglandin-E, and TLR4 ligands, demonstrated to contribute to the peri-conception immune environment. Recent studies show that conception in the absence of seminal plasma in mice impairs embryo development and alters fetal development to impact the phenotype of offspring, with adverse effects on adult metabolic function particularly in males. This review summarises our current understanding of the molecular responses to seminal fluid and how this contributes to the establishment of pregnancy, generation of an immune-regulatory environment and programming long-term offspring health.

The regulation of inflammatory pathways and infectious disease of the cervix by seminal fluid

The connection between human papillomavirus (HPV) infection and the consequent sequelae which establishes cervical neoplastic transformation and invasive cervical cancer has redefined many aspects of cervical cancer research. However there is still much that we do not know. In particular, the impact of external factors, like seminal fluid in sexually active women, on pathways that regulate cervical inflammation and tumorigenesis, have yet to be fully understood. HPV infection is regarded as the initiating noninflammatory cause of the disease; however emerging evidence points to resident HPV infections as drivers of inflammatory pathways that play important roles in tumorigenesis as well as in the susceptibility to other infections such as human immunodeficiency virus (HIV) infection. Moreover there is emerging evidence to support a role for seminal fluid, in particular, the inflammatory bioactive lipids, and prostaglandins which are present in vast quantities in seminal fluid in regulating pathways that can exacerbate inflammation of the cervix, speed up tumorigenesis, and enhance susceptibility to HIV infection. This review will highlight some of our current knowledge of the role of seminal fluid as a potent driver of inflammatory and tumorigenic pathways in the cervix and will provide some evidence to propose a role for seminal plasma prostaglandins in HIV infection and AIDS-related cancer.

Seminal plasma induces the expression of IL-1α in normal and neoplastic cervical cells via EP2/EGFR/PI3K/AKT pathway

Background

Cervical cancer is a chronic inflammatory disease of multifactorial etiology usually presenting in sexually active women. Exposure of neoplastic cervical epithelial cells to seminal plasma (SP) has been shown to promote the growth of cancer cells in vitro and tumors in vivo by inducing the expression of inflammatory mediators including pro-inflammatory cytokines. IL-1α is a pleotropic pro-inflammatory cytokine induced in several human cancers and has been associated with virulent tumor phenotype and poorer prognosis. Here we investigated the expression of IL-1α in cervical cancer, the role of SP in the regulation of IL-1α in neoplastic cervical epithelial cells and the molecular mechanism underlying this regulation.

Methods and results

Real-time quantitative RT-PCR confirmed the elevated expression of IL-1α mRNA in cervical squamous cell carcinoma and adenocarcinoma tissue explants, compared with normal cervix. Using immunohistochemistry, IL-1α was localized to the neoplastically transformed squamous, columnar and glandular epithelium in all cases of squamous cell carcinoma and adenocarcinomas explants studied. We found that SP induced the expression of IL-α in both normal and neoplastic cervical tissue explants. Employing HeLa (adenocarcinoma) cell line as a model system we identified PGE₂ and EGF as possible ligands responsible for SP-mediated induction of IL-1α in these neoplastic cells. In addition, we showed that SP activates EP2/EGFR/PI3kinase-Akt signaling to induce IL-1α mRNA and protein expression. Furthermore, we demonstrate that in normal cervical tissue explants the induction of IL-1α by SP is via the activation of EP2/EGFR/PI3 kinase-Akt signaling.

Conclusion

SP-mediated induction of IL-1α in normal and neoplastic cervical epithelial cells suggests that SP may promote cervical inflammation as well as progression of cervical cancer in sexually active women.

CCR5 expression is elevated in cervical cancer cells and is up-regulated by seminal plasma

The interplay between inflammation, cervical cancer and HIV acquisition in women is poorly understood. We have previously shown that seminal plasma (SP) can promote cervical tumour cell growth in vitro and in vivo via the activation of potent inflammatory pathways. In this study, we investigated whether SP could regulate expression of chemokine receptors with known roles in HIV infection, in the cervix and in cervical cancer. The expression of CD4 and CCR5 was investigated by RT-PCR analysis and immunohistochemistry. CD4 and CCR5 expression was elevated in cervical cancer tissue compared with normal cervix. Ex vivo studies conducted on cervical tissues and HeLa cells showed that SP significantly increases the expression of CD4 and CCR5 transcripts. Furthermore, it was found that SP also up-regulates CCR5 protein in HeLa cells. The regulation of CCR5 expression was investigated following treatment of HeLa cells with SP in the presence/absence of chemical inhibitors of intracellular signalling, EP2 and EP4 antagonists, prostaglandin (PG) E2 and a cyclooxygenase (COX)-1 doxycycline-inducible expression system. These experiments demonstrated that the regulation of CCR5 expression by SP occurs via the epidermal growth factor receptor (EGFR)-COX-1-PGE2 pathway. This study provides a link between activation of inflammatory pathways and regulation of HIV receptor expression in cervical cancer cells.

Role of semen in altering the balance between inflammation and tolerance in the female genital tract: does it contribute to HIV risk?

While the main reproduction aim of semen is the transport of spermatozoa to the female genital tract, seminal plasma is a complex fluid that also carries a broad array of immunologically active molecules. Seminal plasma has been shown to contain a diverse array of anti-inflammatory and pro-inflammatory soluble mediators that regulate immune responses within the female reproductive tract than can facilitate fertilization. Since the natural inflammatory response to semen deposition in the female genital tract may result in recruitment of activated HIV target cells into the female genital mucosa, we discuss the constituents of semen that may increase the risk for HIV infection in women.

Multilevel pharmacological manipulation of adenosine-prostaglandin E₂/cAMP nexus in the tumor microenvironment: a 'two hit' therapeutic opportunity

Novel trends in cancer treatment research are focused on targeting the tumor microenvironment, thereby developing chemo-immunotherapeutic strategies which not only directly kill tumor cells, but also trigger the anti-tumor immune effector responses. Ectonucleotidases (CD39 and CD73)-generated extracellular adenosine and cyclooxygenase-2 (COX2)-derived prostaglandin E₂ (PGE₂) are amongst the tumor microenvironmental factors that have emerged as attractive targets in this regard. Both comprise a pivotal axis in tumor progression and immune escape via autocrine and paracrine activation of a common intracellular signaling pathway, the cAMP-protein kinase A (PKA) pathway, in cancer and immune cells. In this review, we venture a potential and realistic strategy that this adenosine-PGE₂/cAMP nexus is targetable at different levels, thereby pointing out a 'two hit' chemo-immunotherapeutic proposition: direct killing of tumor cells on one hand, and the rescuing of endogenous anti-tumor immune response on the other. The reviewed experimental, preclinical and clinical data provide the proof of concept that 'two hit' multilevel pharmacological manipulation of adenosine-E₂/cAMP nexus is achievable within the tumor microenvironment.

Seminal plasma induces angiogenic chemokine expression in cervical cancer cells and regulates vascular function

Cervical cancer is one of the leading gynecological malignancies in women. We have recently shown that seminal plasma (SP) can regulate the inflammatory cyclooxygenase-prostaglandin pathway and enhance the growth of cervical epithelial tumours in vivo by promoting cellular proliferation and alteration of vascular function. This study investigated the molecular mechanism whereby SP regulates vascular function using an in vitro model system of HeLa cervical adenocarcinoma cells and human umbilical vein endothelial cells (HUVECs). We found that SP rapidly enhanced the expression of the angiogenic chemokines, interleukin (IL)-8 and growth regulated oncogene alpha (GRO) in HeLa cells in a time-dependent manner. We investigated the molecular mechanism of SP-mediated regulation of IL-8 and GRO using a panel of chemical inhibitors of cell signalling. We found that treatment of HeLa cells with SP elevated expression of IL-8 and GRO by transactivation of the epidermal growth factor receptor, activation of extracellular signal-regulated kinase and induction of cyclooxygenase enzymes and nuclear factor kappa B. We investigated the impact of IL-8 and GRO, released from HeLa cells after treatment with SP, on vascular function using a co-culture model system of conditioned medium (CM) from HeLa cells, treated with or without SP, and HUVECs. We found that CM from HeLa cells induced the arrangement of endothelial cells into a network of tube-like structures via the CXCR2 receptor on HUVECs. Taken together our data outline a molecular mechanism whereby SP can alter vascular function in cervical cancers via the pro-angiogenic chemokines, IL-8 and GRO.

Seminal plasma enhances cervical adenocarcinoma cell proliferation and tumour growth in vivo

Cervical cancer is one of the leading causes of cancer-related death in women in sub-Saharan Africa. Extensive evidence has shown that cervical cancer and its precursor lesions are caused by Human papillomavirus (HPV) infection. Although the vast majority of HPV infections are naturally resolved, failure to eradicate infected cells has been shown to promote viral persistence and tumorigenesis. Furthermore, following neoplastic transformation, exposure of cervical epithelial cells to inflammatory mediators either directly or via the systemic circulation may enhance progression of the disease. It is well recognised that seminal plasma contains an abundance of inflammatory mediators, which are identified as regulators of tumour growth. Here we investigated the role of seminal plasma in regulating neoplastic cervical epithelial cell growth and tumorigenesis. Using HeLa cervical adenocarcinoma cells, we found that seminal plasma (SP) induced the expression of the inflammatory enzymes, prostaglandin endoperoxide synthase (PTGS1 and PTGS2), cytokines interleukin (IL) -6, and -11 and vascular endothelial growth factor-A(VEGF-A). To investigate the role of SP on tumour cell growth in vivo, we xenografted HeLa cells subcutaneously into the dorsal flank of nude mice. Intra-peritoneal administration of SP rapidly and significantly enhanced the tumour growth rate and size of HeLa cell xenografts in nude mice. As observed in vitro, we found that SP induced expression of inflammatory PTGS enzymes, cytokines and VEGF-A in vivo. Furthermore we found that SP enhances blood vessel size in HeLa cell xenografts. Finally we show that SP-induced cytokine production, VEGF-A expression and cell proliferation are mediated via the induction of the inflammatory PTGS pathway.

Seminal fluid induces leukocyte recruitment and cytokine and chemokine mRNA expression in the human cervix after coitus

In mice, seminal fluid elicits an inflammation-like response in the female genital tract that activates immune adaptations to advance the likelihood of conception and pregnancy. In this study, we examined whether similar changes in leukocyte and cytokine parameters occur in the human cervix in response to the male partner's seminal fluid. After a period of abstinence in proven-fertile women, duplicate sets of biopsies were taken from the ectocervix in the periovulatory period and again 48 h later, 12 h after unprotected vaginal coitus, vaginal coitus with use of a condom, or no coitus. A substantial influx of CD45(+) cells mainly comprising CD14(+) macrophages and CD1a(+) dendritic cells expressing CD11a and MHC class II was evident in both the stratified epithelium and deeper stromal tissue after coitus. CD3(+)CD8(+)CD45RO(+) T cells were also abundant and increased after coitus. Leukocyte recruitment did not occur without coitus or with condom-protected coitus. An accompanying increase in CSF2, IL6, IL8, and IL1A expression was detected by quantitative RT-PCR, and microarray analysis showed genes linked with inflammation, immune response, and related pathways are induced by seminal fluid in cervical tissues. We conclude that seminal fluid introduced at intercourse elicits expression of proinflammatory cytokines and chemokines, and a robust recruitment of macrophages, dendritic cells, and memory T cells. The leukocyte and cytokine environment induced in the cervix by seminal fluid appears competent to initiate adaptations in the female immune response that promote fertility. This response is also relevant to transmission of sexually transmitted pathogens and potentially, susceptibility to cervical metaplasia.

Prostaglandin E2 regulates renal cell carcinoma invasion through the EP4 receptor-Rap GTPase signal transduction pathway

Prognosis for patients with early stage kidney cancer has improved, but the treatment options for patients with locally advanced disease and metastasis remain few. Understanding the molecular mechanisms that regulate invasion and metastasis is critical for developing successful therapies to treat these patients. Proinflammatory prostaglandin E(2) plays an important role in cancer initiation and progression via activation of cognate EP receptors that belong to the superfamily of G protein-coupled receptors. Here we report that prostaglandin E(2) promotes renal cancer cell invasion through a signal transduction pathway that encompasses EP4 and small GTPase Rap. Inactivation of Rap signaling with Rap1GAP, like inhibition of EP4 signaling with ligand antagonist or knockdown with shRNA, reduces the kidney cancer cell invasion. Human kidney cells evidence increased EP4 and decreased Rap1GAP expression levels in the malignant compared with benign samples. These results support the idea that targeted inhibition of EP4 signaling and restoration of Rap1GAP expression constitute a new strategy to control kidney cancer progression.

International Union of Basic and Clinical Pharmacology. LXXXIII: classification of prostanoid receptors, updating 15 years of progress

It is now more than 15 years since the molecular structures of the major prostanoid receptors were elucidated. Since then, substantial progress has been achieved with respect to distribution and function, signal transduction mechanisms, and the design of agonists and antagonists (http://www.iuphar-db.org/DATABASE/FamilyIntroductionForward?familyId=58). This review systematically details these advances. More recent developments in prostanoid receptor research are included. The DP(2) receptor, also termed CRTH2, has little structural resemblance to DP(1) and other receptors described in the original prostanoid receptor classification. DP(2) receptors are more closely related to chemoattractant receptors. Prostanoid receptors have also been found to heterodimerize with other prostanoid receptor subtypes and nonprostanoids. This may extend signal transduction pathways and create new ligand recognition sites: prostacyclin/thromboxane A(2) heterodimeric receptors for 8-epi-prostaglandin E(2), wild-type/alternative (alt4) heterodimers for the prostaglandin FP receptor for bimatoprost and the prostamides. It is anticipated that the 15 years of research progress described herein will lead to novel therapeutic entities.

Activation of telomerase by seminal plasma in malignant and normal cervical epithelial cells

Seminal fluids are involved in the development of cervical cancer but the underlying mechanism is unclear. Because cellular transformation requires telomerase activation by expression of the telomerase reverse transcriptase (hTERT) gene, we examined the role of seminal fluids in telomerase activation. Significantly elevated hTERT mRNA and telomerase activity were observed in cervical cell lines (HeLa, SiHa and Caski) treated with seminal plasma. Normal cervical epithelial cells expressed minimal levels of hTERT mRNA and telomerase activity, and seminal plasma substantially enhanced both expression and activity. The hTERT promoter activity was similarly increased in seminal plasma-treated HeLa cells and this effect was closely correlated with increased Sp1 expression and binding to the hTERT promoter. Cyclooxygenase-2 (COX-2) was simultaneously increased in HeLa cells exposed to seminal plasma, and blockade of COX-2 induction abolished seminal plasma stimulation of the hTERT promoter activity, hTERT expression and telomerase activity. Prostaglandin E2 (PGE2) mimics the effect of seminal plasma, stimulating Sp1 expression, enhancing Sp1 occupancy on the hTERT promoter and promoter activity. Moreover, tumour growth was robustly enhanced when HeLa cells together with seminal plasma were injected into nude-mice. Taken together, seminal plasma stimulates COX-2-PGE2-Sp1-dependent hTERT transcription, which provides insights into the putative mechanism underlying telomerase activation in cervical epithelial and cancer cells.

Naphthalene/quinoline amides and sulfonylureas as potent and selective antagonists of the EP4 receptor

Two new series of EP(4) antagonists based on naphthalene/quinoline scaffolds have been identified as part of our on-going efforts to develop treatments for inflammatory pain. One series contains an acidic sulfonylurea pharmacophore, whereas the other is a neutral amide. Both series show subnanomolar intrinsic binding potency towards the EP(4) receptor, and excellent selectivity towards other prostanoid receptors. While the amide series generally displays poor pharmacokinetic parameters, the sulfonylureas exhibit greatly improved profile. MF-592, the optimal compound from the sulfonylurea series, has a desirable overall preclinical profile that suggests it is suitable for further development.

Role of semen in HIV-1 transmission: inhibitor or facilitator?

Sexual transmission of human immunodeficiency virus type 1 (HIV-1) accounts for 60-90% of new infections, especially in developing countries. During male-to-female transmission, the virus is typically deposited in the vagina as cell-free and cell-associated virions carried by semen. But semen is more than just a carrier for HIV-1. Evidence from in vitro and in vivo studies supports both inhibitory and enhancing effects. Intrinsic antiviral activity mediated by cationic antimicrobial peptides, cytotoxicity, and blockage of HIV-dendritic cell interactions are seminal plasma properties that inhibit HIV-1 infection. On the contrary, neutralization of vaginal acidic pH, enhanced virus-target cell attachment by seminal amyloid fibrils, opsonization by complement fragments, and electrostatic interactions are factors that facilitate HIV-1 infection. The end result, i.e., inhibition or enhancement of HIV mucosal infection, in vivo, likely depends on the summation of all these biological effects. More research is needed, especially in animal models, to dissect the role of these factors and establish their relevance in HIV-1 transmission.

The role of PGE2 receptor EP4 in pathologic ocular angiogenesis

PURPOSE

PGE(2) binds to PGE(2) receptors (EP(1-4)). The purpose of the present study was to investigate the role of the EP(4) receptor in angiogenic cell behaviors of retinal Müller cells and retinal microvascular endothelial cells (RMECs) and to assess the efficacy of an EP(4) antagonist in rat models of oxygen-induced retinopathy (OIR) and laser-induced choroidal neovascularization (LCNV).

METHODS

Müller cells derived from COX-2-null mice were treated with increasing concentrations of the EP(4) agonist PGE(1)-OH, and wild-type Müller cells were treated with increasing concentrations of the EP(4) antagonist L-161982; VEGF production was assessed. Human RMECs (HRMECs) were treated with increasing concentrations of L-161982, and cell proliferation and tube formation were assessed. Rats subjected to OIR or LCNV were administered L-161982, and the neovascular area was measured.

RESULTS

COX-2-null mouse Müller cells treated with increasing concentrations of PGE(1)-OH demonstrated a significant increase in VEGF production (P < or = 0.0165). Wild-type mouse Müller cells treated with increasing concentrations of L-161982 demonstrated a significant decrease in VEGF production (P < or = 0.0291). HRMECs treated with increasing concentrations of L-161982 demonstrated a significant reduction in VEGF-induced cell proliferation (P < or = 0.0033) and tube formation (P < 0.0344). L-161982 treatment significantly reduced pathologic neovascularization in OIR (P < 0.0069) and LCNV (P < or = 0.0329).

CONCLUSIONS

Preliminary investigation has demonstrated that EP(4) activation or inhibition influences the behaviors of two retinal cell types known to play roles in pathologic ocular angiogenesis. These findings suggest that the EP(4) receptor may be a valuable therapeutic target in neovascular eye disease.

Seminal plasma differentially regulates inflammatory cytokine gene expression in human cervical and vaginal epithelial cells

Exposure to semen elicits an inflammatory response in the female reproductive tract of rodents and other animals. The nature and regulation of any similar response in humans is poorly understood. This study investigated seminal plasma induction of inflammatory cytokine and chemokine gene regulation in human cervical and vaginal epithelial cells in vitro. Affymetrix microarray gene profiling revealed that inflammatory cytokine genes were prevalent among 317 known genes differentially expressed in immortalized ectocervical epithelial (Ect1) cells after incubation with pooled human seminal plasma. A dose- and time-dependent induction by seminal plasma of IL8, IL6, CSF2 and CCL2 mRNA expression in Ect1 cells was verified by quantitative RT-PCR. This was accompanied by increases in Ect1 secretion of immunoactive gene products IL-8, IL-6, GM-CSF and MCP-1. Similar cytokine responses were elicited in primary ectocervical epithelial cells. Endocervical epithelial (End1) and vaginal epithelial (Vk2) cells were less responsive to seminal fluid, with induction of IL-8 and MCP-1, but not GM-CSF or IL-6. In a panel of 10 seminal plasma samples, considerable variation in inflammatory cytokine-inducing activity was evident. These experiments show that seminal plasma can elicit expression of a range of inflammatory cytokines and chemokines in reproductive tract epithelia, and implicate the ectocervix as the primary site of responsiveness, with gene-specific differences in the kinetics and site-restrictedness of the response. Seminal factor regulation of inflammatory cytokines in the cervical epithelium is implicated in controlling the immune response to seminal antigens, and defence against infectious agents introduced at intercourse.

Prostaglandin E2-EP4 receptor promotes endothelial cell migration via ERK activation and angiogenesis in vivo

Prostaglandin E2 (PGE(2)), a major product of cyclooxygenase, exerts its functions by binding to four G protein-coupled receptors (EP1-4) and has been implicated in modulating angiogenesis. The present study examined the role of the EP4 receptor in regulating endothelial cell proliferation, migration, and tubulogenesis. Primary pulmonary microvascular endothelial cells were isolated from EP4(flox/flox) mice and were rendered null for the EP4 receptor with adenoCre virus. Whereas treatment with PGE(2) or the EP4 selective agonists PGE(1)-OH and ONO-AE1-329 induced migration, tubulogenesis, ERK activation and cAMP production in control adenovirus-transduced endothelial EP4(flox/flox) cells, no effects were seen in adenoCre-transduced EP4(flox/flox) cells. The EP4 agonist-induced endothelial cell migration was inhibited by ERK, but not PKA inhibitors, defining a functional link between PGE(2)-induced endothelial cell migration and EP4-mediated ERK signaling. Finally, PGE(2), as well as PGE(1)-OH and ONO-AE1-329, also promoted angiogenesis in an in vivo sponge assay providing evidence that the EP4 receptor mediates de novo vascularization in vivo.