Survivin contributes to the anti-apoptotic activities of transforming growth factor alpha in mouse blastocysts through phosphatidylinositol 3'-kinase pathway

High expression of CFTR in cumulus cells from mature oocytes is associated with high-quality of oocyte and subsequent embryonic development

OBJECTIVE

The purpose of this study was to explore the association of expression of cystic fibrosis transmembrane conductance regulator (CFTR) in cumulus cells (CCs) from mature oocytes with oocyte quality and embryonic development.

METHODS

A total of 338 infertile women who underwent ovarian stimulation cycle of oocyte retrieval in Zhejiang University School of Medicine were retrospectively enrolled in this study. The relative mRNA expression levels of CFTR, bone morphogenetic protein 15 (BMP15), and growth differentiation factor 9 (GDF9) in CCs were detected by qPCR technology. ROC curve was applied for the diagnosis of oocyte maturation. The serum levels of anti-Müllerian hormone (AMH), E2, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and androstenedione were measured. Oocyte maturation rate, fertilization rate, cleavage rate, high-quality embryo formation rate, and implantation rate after embryo transfer were also determined.

RESULTS

The mRNA expression levels of CFTR in CCs were significantly increased in metaphase II (MII) oocytes compared to that in metaphase I (MI) or germinal vesicle (GV) oocytes. The ROC curve analysis illustrated that CFTR mRNA expression could efficiently discriminate MII oocytes from MI or GV oocytes (AUC = 0.954), and revealed that 0.695 RQU is the optimal cut-off value for diagnosis. So the cut-off value of 2-ΔΔCT = 0.70 was used to divide the patients into two groups: low- (n = 114) and high-CFTR group (n = 224). The mRNA expression of CFTR in CCs was positively correlated with the antral follicular count (AFC), number of oocytes retrieved, number of MII oocytes, serum E2 level on hCG day, and BMP15 and GDF9 expression in CCs. Under continuous stimulation with the same dose of recombinant follicle-stimulating hormone (rFSH), the number of follicles, average recovered oocytes, recovered oocytes, MII oocytes, as well as the oocyte recovery rate, fertilization rate, oocyte cleavage rate, high-quality embryo formation rate, and implantation rate were decreased in patients with lower CFTR.

CONCLUSIONS

This study suggests that CFTR expression in CCs is associated with the developmental potential of human oocytes.

Protein kinase Akt2/PKBβ is involved in blastomere proliferation of preimplantation mouse embryos

Activation of Akt/Protein Kinase B (PKB) by phosphatidylinositol-3-kinase (PI3K) controls several cellular functions largely studied in mammalian cells, including preimplantation embryos. We previously showed that early mouse embryos inherit active Akt from oocytes and that the intracellular localization of this enzyme at the two-cell stage depends on the T-cell leukemia/lymphoma 1 oncogenic protein, Tcl1. We have now investigated whether Akt isoforms, namely Akt1, Akt2 and Akt3, exert a specific role in blastomere proliferation during preimplantation embryo development. We show that, in contrast to other Akt family members, Akt2 enters male and female pronuclei of mouse preimplantation embryos at the late one-cell stage and thereafter maintains a nuclear localization during later embryo cleavage stages. Depleting one-cell embryos of single Akt family members by microinjecting Akt isoform-specific antibodies into wild-type zygotes, we observed that: (a) Akt2 is necessary for normal embryo progression through cleavage stages; and (b) the specific nuclear targeting of Akt2 in two-cell embryos depends on Tcl1. Our results indicate that preimplantation mouse embryos have a peculiar regulation of blastomere proliferation based on the activity of the Akt/PKB family member Akt2, which is mediated by the oncogenic protein Tcl1. Both Akt2 and Tcl1 are essential for early blastomere proliferation and embryo development.

Role of cAMP modulator supplementations during oocyte in vitro maturation in domestic animals

Cyclic adenosine monophosphate (cAMP) is an important molecule in signal transduction within the cell, functioning as a second cell messenger of gonadotrophin stimulation. The concentration of cAMP in cumulus-oocyte complexes (COCs) is known to be controlled through modulation of its synthesis by adenylyl cyclase (AC) and by degradation through the cyclic nucleotide phosphodiesterase (PDE) enzymes. One of the main obstacles for in vitro embryo production is the optimization of reproduction processes that occur in oocyte maturation. The function of cAMP is important in maintaining meiotic arrest in mammalian oocytes. When the oocyte is physically removed from the antral follicle for in vitro maturation (IVM), intra-oocyte cAMP concentrations decrease and spontaneous meiotic resumption begins, due to the depletion of inhibitory factors from the follicle. In many studies, relatively greater cAMP concentrations before IVM has been reported to improve oocyte competence, leading to subsequent benefits in embryonic development in different species. There, therefore, has been an increase in oocyte cAMP concentrations with several treatments and different approaches, such as invasive AC, stimulators of AC activity, PDE inhibitors, and cAMP analogs. The aim of this review is to comprehensively evaluate and provide data related to (i) the use of cAMP modulators during IVM and the effects on completion of meiosis and cytoplasmic reorganization, which are required for development of oocytes with the capacity to contribute to fertilization and subsequent embryonic development; and (ii) the main cAMP modulators and the effects when used in oocyte IVM.

Global, Survival, and Apoptotic Transcriptome during Mouse and Human Early Embryonic Development

Survival and cell death signals are crucial for mammalian embryo preimplantation development. However, the knowledge on the molecular mechanisms underlying their regulation is still limited. Mouse studies are widely used to understand preimplantation embryo development, but extrapolation of these results to humans is questionable. Therefore, we wanted to analyse the global expression profiles during early mouse and human development with a special focus on genes involved in the regulation of the apoptotic and survival pathways. We used DNA microarray technology to analyse the global gene expression profiles of preimplantation human and mouse embryos (metaphase II oocytes, embryos at the embryonic genome activation stage, and blastocysts). Components of the major apoptotic and survival signalling pathways were expressed during early human and mouse embryonic development; however, most expression profiles were species-specific. Particularly, the expression of genes encoding components and regulators of the apoptotic machinery were extremely stable in mouse embryos at all analysed stages, while it was more stage-specific in human embryos. CASP3, CASP9, and AIF were the only apoptosis-related genes expressed in both species and at all studied stages. Moreover, numerous transcripts related to the apoptotic and survival pathway were reported for the first time such as CASP6 and IL1RAPL1 that were specific to MII oocytes; CASP2, ENDOG, and GFER to blastocysts in human. These findings open new perspectives for the characterization and understanding of the survival and apoptotic signalling pathways that control early human and mouse embryonic development.

Iloprost supports early development of in vitro-produced porcine embryos through activation of the phosphatidylinositol 3-kinase/AKT signalling pathway

Despite evidence of the presence of prostaglandin (PG) I₂ in mammalian oviducts, its role in early development of in vitro-produced (IVP) embryos is largely unknown. Thus, in the present study we examined the effects of iloprost, a PGI₂ analogue, on the in vitro developmental competence of early porcine embryos and the underlying mechanism(s). To examine the effects of iloprost on the development rate of IVF embryos, iloprost was added to the in vitro culture (IVC) medium and cultured for 6 days. Supplementation of the IVC medium with iloprost significantly improved developmental parameters, such as blastocyst formation rate, the trophectoderm:inner cell mass ratio and cell survival in IVF and parthenogenetically activated (PA) embryos. In addition, post-blastulation development into the expanded blastocyst stage was improved in iloprost-treated groups compared with controls. Interestingly, the phosphatidylinositol 3-kinase (PI3K)/AKT signalling pathway was significantly activated by iloprost supplementation in a concentration-dependent manner (10-1000nM), and the beneficial effects of iloprost on the early development of porcine IVF and PA embryos was completely ablated by treatment with 2.5μM wortmannin, a PI3K/AKT signalling inhibitor. Importantly, expression of the PI3K/AKT signalling pathway was significantly reduced in somatic cell nuclear transfer (SCNT) compared with IVF embryos, and iloprost supported the early development of SCNT embryos, as was the case for IVF and PA embryos, suggesting a consistent effect of iloprost on the IVC of IVP porcine embryos. Together, these results indicate that iloprost can be a useful IVC supplement for production of IVP early porcine embryos with high developmental competence.

MUC1-C drives myeloid leukaemogenesis and resistance to treatment by a survivin-mediated mechanism

Acute myeloid leukaemia (AML) is an aggressive haematological malignancy with an unmet need for improved therapies. Responses to standard cytotoxic therapy in AML are often transient because of the emergence of chemotherapy‐resistant disease. The MUC1‐C oncoprotein governs critical pathways of tumorigenesis, including self‐renewal and survival, and is aberrantly expressed in AML blasts and leukaemia stem cells (LSCs). However, a role for MUC1‐C in linking leukaemogenesis and resistance to treatment has not been described. In this study, we demonstrate that MUC1‐C overexpression is associated with increased leukaemia initiating capacity in an NSG mouse model. In concert with those results, MUC1‐C silencing in multiple AML cell lines significantly reduced the establishment of AML in vivo. In addition, targeting MUC1‐C with silencing or pharmacologic inhibition with GO‐203 led to a decrease in active β‐catenin levels and, in‐turn, down‐regulation of survivin, a critical mediator of leukaemia cell survival. Targeting MUC1‐C was also associated with increased sensitivity of AML cells to Cytarabine (Ara‐C) treatment by a survivin‐dependent mechanism. Notably, low MUC1 and survivin gene expression were associated with better clinical outcomes in patients with AML. These findings emphasize the importance of MUC1‐C to myeloid leukaemogenesis and resistance to treatment by driving survivin expression. Our findings also highlight the potential translational relevance of combining GO‐203 with Ara‐C for the treatment of patients with AML.

The correlation between microRNA490-3p and TGFα in endometrial carcinoma tumorigenesis and progression

MicroRNAs (miRNAs) are small non-coding RNAs that negatively regulate the translation of messenger RNAs by binding their 3′-untranslated region (3′ UTR). MiR-490-3p has been reported to be a suppressor in various human cancers; however, little is known about the biological functions of miR-490-3p in endometrial cancer (EC). In our study, we found that MiR-490-3p mRNA expression was significantly lower in ECs than in normal endometrial tissues. MiR-490-3p mRNA expression was also negatively associated with depth of invasion (mucosa vs. muscular and serosa) and lymph node metastasis (negative vs. positive) in EC. MiR-490-3p overexpression reduced proliferation; promoted G1 arrest and apoptosis; suppressed migration and invasion; and reduced TGFα, NF-kB, cyclin D1, survivin, matrix metalloproteinase 2 (MMP2) mRNA and protein expression, and improved Bax mRNA and protein expression. The dual-luciferase reporter assay indicated that miR-490-3p directly targeted TGFα by binding its 3′ untranslated region. MiR-490-3P transfection also suppressed tumor development and TGFα expression (as determined by immunohistochemistry and western blotting) in vivo in the xenograft mouse model. This is the first demonstration that miR-490-3P might act as a suppressor in EC tumorigenesis and progression by targeting TGFα. Our results provide a theoretical basis for the further study on the molecular target for endometrial cancer.

Female tract cytokines and developmental programming in embryos

In the physiological situation, cytokines are pivotal mediators of communication between the maternal tract and the embryo. Compelling evidence shows that cytokines emanating from the oviduct and uterus confer a sophisticated mechanism for 'fine-tuning' of embryo development, influencing a range of cellular events from cell survival and metabolism, through division and differentiation, and potentially exerting long-term impact through epigenetic remodelling. The balance between survival agents, including GM-CSF, CSF1, LIF, HB-EGF and IGFII, against apoptosis-inducing factors such as TNFα, TRAIL and IFNg, influence the course of preimplantation development, causing embryos to develop normally, adapt to varying maternal environments, or in some cases to arrest and undergo demise. Maternal cytokine-mediated pathways help mediate the biological effects of embryo programming, embryo plasticity and adaptation, and maternal tract quality control. Thus maternal cytokines exert influence not only on fertility and pregnancy progression but on the developmental trajectory and health of offspring. Defining a clear understanding of the biology of cytokine networks influencing the embryo is essential to support optimal outcomes in natural and assisted conception.

Expression of survivin in human oocytes and preimplantation embryos

OBJECTIVE

To determine whether [1] survivin is expressed in human oocytes and embryos; [2] embryos grown in vitro secrete survivin protein; and [3] survivin levels are correlated with embryo cleavage rates.

DESIGN

Experimental.

SETTING

University-affiliated IVF clinic.

PATIENT(S)

Couples undergoing IVF-ET cycles.

INTERVENTION(S)

Conventional reverse transcriptase-polymerase chain reaction (PCR), real-time PCR, immunohistochemistry, Western blot on oocytes, embryos and control choriocarcinoma JEG-3 cells, and ELISA analysis of conditioned culture media.

MAIN OUTCOME MEASURE(S)

Detection of survivin mRNA and protein in oocytes and preimplantation embryos and in JEG-3 cancer cells. Detection of survivin concentrations in embryo culture media.

RESULT(S)

Survivin mRNA and protein were expressed during human oocyte maturation, from germinal vesicle to metaphase II stage, and throughout embryo development, from pronuclear stage to blastocyst stage. Survivin was localized predominantly in the cytoplasm of all cells examined and in the oocytes on the chromatin of metaphase chromosomes and midbodies. Western blot analysis of human oocyte and cancer cell extracts detected a full-length (primary) survivin band of 16.5 kDa. Survivin was also detected in conditioned media samples from embryo cultures and showed a positive correlation with embryo cleavage rates.

CONCLUSION(S)

Our data have demonstrated for the first time that human oocytes/embryos not only express but also secret survivin, suggesting that survivin may play an important role in human oogenesis and embryogenesis.

Suppression of hydatidiform molar growth by inhibiting endogenous brain-derived neurotrophic factor/tyrosine kinase B signaling

Brain-derived neurotrophic factor (BDNF)/tyrosine kinase B (TrkB) receptor signaling promotes trophoblast growth in normal and abnormal pregnancy. It also regulates the growth of malignant trophoblastic, choriocarcinoma cells. However, possible involvement of this signaling system in hydatidiform mole, another major gestational trophoblastic disease, has not been determined. Here, we found the expression of BDNF in syncytiotrophoblasts and its receptor, TrkB, in cytotrophoblasts of hydatidiform mole using real-time RT-PCR and immunoassays. In molar explant cultures, treatment with soluble TrkB ectodomain or a Trk receptor inhibitor K252a inhibited trophoblast outgrowth as well as decreased cytotrophoblast proliferation and cellular viability based on histopathological analyses and glucose metabolism monitoring. These inhibitors also increased apoptosis and caspase-3/7 activities. In an in vivo model of hydatidiform molar growth based on xenotransplantation of molar tissues into kidney capsules of SCID mice, treatment with K252a suppressed molar growth as reflected by decreased trophoblast proliferation and their invasion into mouse kidney, reduced tissue levels of chorionic gonadotropin-β, and increased apoptosis. Based on PCR array analyses to identify changes in expression profiles of cell cycle- and apoptosis-related genes in cultured molar explants, suppression of endogenous TrkB signaling led to decreases in key cell cycle-stimulatory and checkpoint genes together with the down-regulation of different antiapoptotic genes. Our findings demonstrate the importance of paracrine signaling by the BDNF/TrkB system in the proliferation and survival of molar trophoblasts. Inhibition of BDNF/TrkB signaling could provide a novel medical treatment for hydatidiform mole.

Inhibition of uterine sarcoma cell growth through suppression of endogenous tyrosine kinase B signaling

Uterine leiomyosarcoma is an aggressive tumor typically found at advanced stages due to difficulties with early diagnosis. Because uterine leiomyosarcoma is resistant to conventional radiation and chemotherapy, the development of more potent medical therapeutics is anticipated. Using quantitative real-time RT-PCR and immunostaining, we found the expression of brain-derived neurotrophic factor (BDNF) and neurotropin-4/5, together with their receptor, tyrosine kinase B (TrkB), in different uterine sarcoma cell lines and primary tumor samples from uterine leiomyosarcoma patients. We noted that levels of BDNF were more abundant than those of neurotropin-4/5. Moreover, the expression of TrkB and its ligands was elevated in a multidrug-resistant cell line and samples obtained from patients with leiomyosarcoma. In cultured uterine sarcoma cells, inhibition of endogenous TrkB signaling by treatment with either the soluble TrkB ectodomain or the Trk receptor inhibitor, K252a, suppressed cell proliferation and increased apoptosis based on cell viability and proliferation, in situ terminal deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate nick end-labeling and caspase-3/7 assays, whereas an inactive plasma membrane nonpermeable K252b was ineffective. Correspondingly, treatment with exogenous BDNF increased cell proliferation. In in vivo studies in athymic nude mice bearing multidrug-resistant uterine sarcoma cell tumors, we demonstrate suppression of tumor growth by treatment with K252a, but not K252b, as reflected by decreased cell proliferation and increased levels of apoptosis and caspase-3/7 activities without obvious side effects. Our findings indicated that endogenous signaling of the TrkB pathway contributed to uterine sarcoma cell growth, and inhibition of TrkB signaling in these tumors could provide a novel medical therapy for patients with uterine sarcomas.

Survival signaling in the preimplantation embryo

The autopoietic development of the preimplantation embryo may in part be explained by the actions of autocrine tropic ligands. The net effect of these mediators is to support the survival of cells within the early embryo. In the mouse, the actions of autocrine ligands are required by the 2-cell stage of development, and they can act in concert with paracrine mediators present within the reproductive tract. These mediators act via 1-o-phosphatidylinositol-3-kinase signaling which has the dual effects of activating calcium/calmodulin-dependent kinase/CREB transcription factor and AKT (protein kinase B)/MDM2 mediated survival pathways. The activated CREB drives transcription of prosurvival effectors, including the proto-oncogenes c-Fos and Bcl2. The AKT induces the phosphorylation and activation of MDM2 which causes the ubiquitination and resultant degradation of P53 resulting in the latency of P53 action. Tropic signals provide coordinated mechanisms for maintaining the survival of the cells of the early embryo. Disturbance of survival signaling has the net effect of reducing the number of cells populating the early embryo, due in part to the P53-mediated reduction in the pluripotent inner cell mass stem cell population within the embryo. The resultant embryos have a markedly reduced capacity for development beyond the implantation stage and those that do implant tend to be anembryonic.

Brain-derived neurotrophic factor/tyrosine kinase B signaling regulates human trophoblast growth in an in vivo animal model of ectopic pregnancy

Although medical treatment of unruptured ectopic pregnancy using methotrexate has been established, development of more potent and safer medical treatment is needed due to limited indications and side effects of methotrexate. Brain-derived neurotrophic factor (BDNF) signals through its receptor tyrosine kinase B (TrkB) to regulate the growth of malignant trophoblastic, choriocarcinoma cell. We investigated possible involvement of this signaling system in nonmalignant human trophoblast growth in both ectopic and intrauterine pregnancy. Here, we demonstrated the expression of BDNF in syncytiotrophoblasts and extravillous trophoblasts (EVTs) together with TrkB in cytotrophoblasts and EVTs in human placental villi during both normal and ectopic pregnancies. Treatment of cultured villous explants with soluble TrkB ectodomain or a Trk receptor inhibitor K252a suppressed cytotrophoblast differentiation by inhibiting EVT outgrowth reflected by decreased levels of an EVT marker, human leukocyte antigen-G. These inhibitors also decreased cytotrophoblast proliferation and cellular viability based on histopathological analyses and monitoring glucose metabolism, together with increased apoptosis in cytotrophoblasts based on in situ terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end-labeling and caspase-3/7 assays. After xenotransplantation of human placental villi into SCID mice as an in vivo model of ectopic pregnancy, treatment with K252a suppressed transplanted villi growth as reflected by decreased cytotrophoblast differentiation and proliferation, reduced tissue levels of chorionic gonadotropin-β, and increased apoptosis and caspase-3/7 activities. Thus, paracrine signaling by the BDNF/TrkB system is important for human cytotrophoblast differentiation, proliferation, and survival, and inhibition of BDNF/TrkB signaling in cytotrophoblasts could provide a novel medical treatment for ectopic pregnancy.

The treatment of TBI with human marrow stromal cells impregnated into collagen scaffold: functional outcome and gene expression profile

We have previously demonstrated that human marrow stromal cells (hMSCs) embedded in collagen I scaffolds significantly enhance the restorative therapeutic effect of hMSCs after traumatic brain injury (TBI). In this study, we test the hypothesis that the collagen scaffold alters gene expression in hMSCs and that hMSCs impregnated into scaffolds increase the astrocytic expression of vascular endothelial growth factor (VEGF) in the injured brain. Following TBI induced by controlled cortical impact injury, scaffold with hMSCs (3.0×10(6)), hMSCs-only and saline were implanted into the lesion cavity one week after brain injury (n=8/each group). Morris water maze and modified neurological severity scores were performed to evaluate the spatial learning and sensorimotor functions, respectively. Lesion volume and expression of VEGF were measured one week after different treatments. In vitro, total RNA from hMSCs was extracted one week after culture with or without collagen I scaffold for evaluation of gene microarrays. Furthermore, an RT-PCR study on a select subgroup of genes was performed to identify the changes of expression between the culturing hMSCs with collagen scaffolds and hMSCs only. The treatment of TBI with collagen scaffold impregnated with hMSCs significantly decreases the functional deficits from TBI within 7days after treatment, and significantly enhances the VEGF expression of astrocytes in the injured brain compared to the hMSCs-only group. In vitro data indicate that collagen scaffolds stimulate hMSCs to express multiple factors which may contribute to hMSC survival, tissue repair and functional recovery after TBI.

Transformation-related protein 53 expression in the early mouse embryo compromises preimplantation embryonic development by preventing the formation of a proliferating inner cell mass

The developmental viability of the preimplantation embryo requires the successful formation of a cluster of pluripotent stem cells called the inner cell mass. Development is variably compromised by a range of exogenous stressors (including their production by assisted reproductive technologies). Inbred C57BL/6 strain embryos are particularly susceptible to the stresses associated with embryo culture, whereas hybrid embryos are more resistant, and this is accounted for in part by the overexpression of transformation-related protein 53 in cultured inbred embryos compared with similarly treated hybrid embryos or embryos not subjected to culture. We show here that this loss of viability is a consequence of the Trp53-dependent reduction in the capacity of blastocysts to form a proliferating inner cell mass. Formation of the trophectodermal line was not adversely affected by these stresses.

Inhibition of brain-derived neurotrophic factor/tyrosine kinase B signaling suppresses choriocarcinoma cell growth

Brain-derived neurotrophic factor (BDNF) signals through its receptor tyrosine kinase (Trk)B to regulate the development trophoblast cells during peri- and postimplantation periods. Possible involvement of this signaling system in malignant human trophoblastic cell growth has not been investigated. Here, we found the expression of BDNF and neurtropin-4/5 together with TrkB in human trophoblastic choriocarcinoma cells. Treatment of cultured choriocarcinoma cells with a soluble TrkB ectodomain or a Trk receptor inhibitor K252a suppressed cell proliferation and increased apoptosis associated by the disruption of mitochondrial functions, whereas an inactive plasma membrane nonpermeable K252b was ineffective. Studies using these specific inhibitors also indicated the importance of the phosphatidylinositol 3-kinase and ERK pathways in mediating BDNF actions. Based on PCR array analyses to identify changes in expression profiles of cell cycle- and apoptosis-related genes in cultured choriocarcinoma cells, we found that suppression of endogenous TrkB signaling led to decreases in key proproliferation cell cycle genes and increases in two inhibitory cell cycle genes together with the up-regulation of several proapoptotic genes. In vivo studies in athymic nude mice bearing choriocarcinoma cell tumors further demonstrated that treatment with K252a, but not K252b, suppressed tumor growth accompanied by decreased cell proliferation, reduced levels of a tumor marker, human chorionic gonadotropin-beta, and increased levels of apoptosis and caspase-3/7 activities. Thus, autocrine signaling of the BDNF/TrkB system is important for human choriocarcinoma cell growth, and inhibition of BDNF/TrkB signaling in these cells could provide a novel therapy for patients with choriocarcinoma.

Effect of the association of IGF-I, IGF-II, bFGF, TGF-beta1, GM-CSF, and LIF on the development of bovine embryos produced in vitro

This study examined the influence of the following growth factors and cytokines on early embryonic development: insulin-like growth factors I and II (IGF-I, IGF-II), basic fibroblast growth factor (bFGF), transforming growth factor (TGF-beta), granulocyte-macrophage colony-stimulating factor (GM-CSF), and leukemia inhibitory factor (LIF). Synthetic oviduct fluid (SOF) was used as the culture medium. We studied the development of bovine embryos produced in vitro and cultured until Day 9 after fertilization. TGF-beta1, bFGF, GM-CSF, and LIF used on their own significantly improved the yield of hatched blastocysts. IGF-I, bFGF, TGF-beta1, GM-CSF, and LIF significantly accelerated embryonic development, especially the change from the expanded blastocyst to hatched blastocyst stages. Use of a combination of these growth factors and cytokines (GF-CYK) in SOF medium produced higher percentages of blastocysts and hatched blastocysts than did use of SOF alone (45% and 22% vs. 24% and 12%; P<0.05) on Day 8 after in vitro fertilization and similar results to use of SOF+10% fetal calf serum (38% and 16%, at the same stages, respectively). The averages of total cells, inner cell mass cells, and trophectoderm cells of exclusively in vitro Day-8 blastocysts for pooled GF-CYK treatments were higher than those for SOF and similar to those for fetal calf serum. The presence of these growth factors and cytokines in the embryo culture medium therefore has a combined stimulatory action on embryonic development; in particular through an increase in hatching rate and in the number of cells of both the inner cell mass and trophoblast. These results are the first to demonstrate that use of a combination of recombinant growth factors and cytokine, as IGF-I, IGF-II, bFGF, TGF-beta1, LIF, and GM-CSF, produces similar results to 10% fetal calf serum for the development of in vitro-produced bovine embryos. This entirely synthetic method of embryo culture has undeniable advantages for the biosecurity of embryo transfer.

Brain-derived neurotrophic factor promotes implantation and subsequent placental development by stimulating trophoblast cell growth and survival

Successful implantation of the blastocyst and subsequent placental development is essential for reproduction. Expression of brain-derived neurotrophic factor (BDNF) and neurotrophin-4/5, together with their receptor, tyrosine kinase B (TrkB), in trophectoderm cells of blastocyst suggests their potential roles in implantation and placental development. Here we demonstrated that treatment with BDNF promoted blastocyst outgrowth, but not adhesion, in vitro and increased levels of the cell invasion marker matrix metalloproteinase-9 in cultured blastocysts through the phosphatidylinositol 3-kinase pathway. After implantation, BDNF and neurotrophin-4/5 proteins as well as TrkB were expressed in trophoblast cells and placentas during different stages of pregnancy. Both TrkB and its ligands were also expressed in decidual cells. Treatment of cultured trophoblast cells with the TrkB ectodomain, or a Trk receptor inhibitor K252a, suppressed cell growth as reflected by decreased proliferation and increased apoptosis, whereas an inactive plasma membrane nonpermeable K252b was ineffective. Studies using the specific inhibitors also indicated the importance of the phosphatidylinositol 3-kinase/Akt pathway in mediating the action of TrkB ligands. In vivo studies in pregnant mice further demonstrated that treatment with K252a, but not K252b, suppressed placental development accompanied by increases in trophoblast cell apoptosis and decreases in placental labyrinth zone at midgestation. In vivo K252a treatment also decreased fetal weight at late gestational stages. Our findings suggested important autocrine/paracrine roles of the BDNF/TrkB signaling system during implantation, subsequent placental development, and fetal growth by increasing trophoblast cell growth and survival.

Ethanol-TGFalpha-MEK signaling promotes growth of human hepatocellular carcinoma

BACKGROUND

Chronic ethanol intake is a significant risk factor for the development of cirrhosis and hepatocellular carcinoma (HCC). The effects of ethanol on extracellular signal-regulated kinase (ERK) activation, transforming growth factor alpha (TGF-alpha), and HCC growth were examined in this study.

METHODS

HepG2, SKHep, Hep3B human HCC cells, or normal human hepatocytes were treated with ethanol (0-100 mM), exogenous TGF-alpha, TGF-alpha neutralization antibody or the MEK inhibitor U0126. TGF-alpha levels were quantified by ELISA. Growth was determined by trypan blue-excluded cell counts. Cell cycle phase distribution was determined by flow cytometry. Protein expression was determined by Western blot.

RESULTS

Ethanol treatment (10-40 mM) increased ERK activation in HepG2 and SKHep HCC cells but not in Hep3B or human hepatocyte cells. Growth increased in HepG2 (174 +/- 29%, P < 0.05) and SKHep (149 +/- 12%, P < 0.05) cells in response to ethanol treatment. Correspondingly, ethanol increased S phase distribution in these cells. U0126 suppressed ethanol-induced growth increases. Ethanol treatment for 24 h also raised TGF-alpha levels in HepG2 cells (118%-198%) and SKHep cells (112%-177%). Exogenous administration of recombinant TGF-alpha mimicked the ethanol-induced growth in HepG2 and SKHep cells; TGF-alpha neutralization antibody effectively abrogated this effect. The TGF-a neutralization antibody also prevented ERK activation by ethanol in HepG2 cells.

CONCLUSIONS

These data demonstrate that clinically relevant doses of ethanol stimulate ERK-dependent proliferation of HCC cells. Ethanol up-regulates TGF-alpha levels in HCC cells and enhances growth through cell cycles changes, which appear to be mediated through TGF-alpha-MEK-ERK signaling. Ethanol-MEK signaling in normal hepatocytes is absent, suggesting that ethanol promotion of HCC growth may in part depend upon the acquisition of cancer-specific signaling by hepatocytes.

A novel combination: ranpirnase and rosiglitazone induce a synergistic apoptotic effect by down-regulating Fra-1 and Survivin in cancer cells

Accumulating evidence supports the idea that two known phosphatidylinositol 3'-kinase (PI3K) downstream proteins, Fra-1 and Survivin, are potential targets for cancer therapy. Increased expression of Fra-1, a Fos family member of the transcription factor activator protein-1, has been implicated in both the maintenance and the progression of the transformed state of several cancer cells. In addition, high Survivin expression in tumors correlates with more aggressive behavior, lower response to chemotherapeutic drugs, and shortened survival time. Previously, we reported that, in malignant mesothelioma cells with increased PI3K activity, small-molecule inhibitors of the PI3K/AKT pathway acted cooperatively with the amphibian RNase chemotherapeutic drug ranpirnase to inhibit cell growth. Because the thiazolidinedione antidiabetic drug rosiglitazone targets the PI3K/AKT pathway, we investigated the effect of the combination of these two drugs in cell survival in several cancer cell lines. We show here that the combination of ranpirnase and rosiglitazone synergistically decreases cell viability and increases cell apoptosis in several cancer cell lines. Cell killing is associated with decreased Fra-1 and Survivin expression and knockdown of Fra-1 increases cell killing by ranpirnase in a dose-dependent manner but not by rosiglitazone. The drug combination does not have a synergistic effect on killing in Fra-1 knockdown cells, showing that Fra-1 modulation accounts in part for the synergism. The novel drug combination of ranpirnase and rosiglitazone is a promising combination to treat cancers with increased PI3K-dependent Fra-1 expression or Survivin.

Phosphatidylinositol 3-kinase signaling in mammalian preimplantation embryo development

The development of the preimplantation mammalian embryo is an autopoietic process; once initiated development proceeds without an absolute requirement for external information or growth cues. This developmental autonomy is partly explained by the generation of autocrine trophic ligands that are released and act back on the embryo via specific receptors. Several embryotrophic ligands cause receptor-dependent activation of 1-o-phosphatidylinositol 3-kinase. This enzyme phosphorylates phosphatidylinositol-4,5-bisphosphate to form phosphatidylinositol-3,4,5-trisphosphate. Genetic or pharmacological ablation of this enzyme activity disrupts normal development of preimplantation embryos. Phosphatidylinositol-3,4,5-trisphosphate is a membrane lipid that acts as a docking site for a wide range of proteins possessing the pleckstrin homology (PH) domain. Such proteins are important regulators of cell survival, proliferation, and differentiation. RAC-alpha serine/threonine protein kinase is an important PH domain protein and its activity is required for normal preimplantation embryo development and survival. The activity of a range of PH domain proteins is also implicated in the normal development of the embryo. This review critically examines the evidence for the activation of 1-o-phosphatidylinositol 3-kinase in the generation of pleiotypic trophic response to embryotrophins in the autopoietic development of the preimplantation embryo.

Regulation of DNA synthesis in mouse embryonic stem cells by transforming growth factor-alpha: involvement of the PI3-K/Akt and Notch/Wnt signaling pathways

This study examined the mechanisms by which transforming growth factor (TGF)-alpha regulates proliferation of mouse embryonic stem (ES) cells. TGF-alpha increased [3H] thymidine and BrdU incorporation in a time- (0-72 h) and dose-dependent (0-10 ng/ml) manner. TGF-alpha stimulated the phosphorylation of Akt, mammalian target of rapamycin (mTOR), p70S6K1 and p44/42 mitogen-activated protein kinases (MAPKs). TGF-alpha also increased the protein levels of Notch, Notch intracellular domain, Hes-1 and Wnt1. However, TGF-alpha-induced DNA synthesis was blocked by inhibition of Akt, mTOR, p44/42 MAPKs and Notch. TGF-alpha increased the gene expression of c-jun, c-myc and c-fos. Moreover, TGF-alpha increased cyclin D/CDK 4 and cyclin E/CDK 2 levels, while decreasing p21cip1/waf1 and p27kip1, which were blocked by the inhibition of Akt, mTOR and Notch. In conclusion, TGF-alpha regulated DNA synthesis of mouse ES cells via PI3-K/Akt, p44/42 MAPKs and Notch/Wnt pathways.

Completion of Meiosis I of preovulatory oocytes and facilitation of preimplantation embryo development by glial cell line-derived neurotrophic factor

Optimal maturation of oocytes and successful development of preimplantation embryos is essential for reproduction. We performed DNA microarray analyses of ovarian transcripts and identified glial cell line-derived neurotrophic factor (GDNF) secreted by cumulus, granulosa, and theca cells as an ovarian factor stimulated by the preovulatory LH/hCG surge. Treatment of cumulus-oocyte complexes with GDNF enhanced first polar body extrusion with increase in cyclin B1 synthesis and the GDNF actions are likely mediated by its receptor GDNF family receptor-alpha1 (GFRA1) and a co-receptor ret proto-oncogene (Ret), both expressed in oocytes. However, treatment with GDNF did not affect germinal vesicle breakdown and cytoplasmic maturation of oocytes. During the preimplantation stages, GDNF was expressed in pregnant oviducts and uteri, whereas GFRA1 and Ret were expressed in embryos throughout early development with an increase after the early blastocyst stage. In blastocysts, both GDNF and GFRA1 were exclusively localized in trophectoderm cells, whereas Ret was detected in both cell lineages. Treatment with GDNF promoted the development of two-cell-stage embryos into blastocysts showing increased cell proliferation and decreased apoptosis mainly in trophectoderm cells. Our findings suggest potential paracrine roles of GDNF in the promotion of completion of meiosis I and the development of early embryos.

Regulation of preimplantation embryo development by brain-derived neurotrophic factor

Hormonal factors secreted by embryos and reproductive tracts are important for successful development of preimplantation embryos. We found expression of brain-derived neurotrophic factor (BDNF) and neurotrophin-4/5 (NT-4/5) transcripts at its highest levels in the blastocyst stages. The transcripts for their receptor, TrkB, were detectable throughout the early embryonic stages with an increase after the early blastocyst stage. Both BDNF and TrkB are expressed in trophectoderm cells, whereas ligand-binding studies indicated specific binding of BDNF to trophectoderm cells. Furthermore, BDNF and NT-4/5 were produced in pregnant oviducts and uteri. Treatment with BDNF promoted the development of two-cell-stage embryos into blastocysts showing increased proliferation and decreased apoptosis. The effects of BDNF were blocked by the TrkB ectodomain or a Trk receptor inhibitor, K252a. Studies using specific inhibitors demonstrated the roles of the PI3K, but not the ERK, pathway in mediating BDNF actions. Under high-density embryo cultures, treatment with the TrkB ectodomain or K252a alone also inhibited embryonic development and survival, suggesting potential autocrine actions of BDNF produced by the embryo. In vivo experiments further demonstrated that K252a treatment suppressed early embryo development by inhibiting blastocyst cell numbers, and increasing blastocyst apoptosis. Our findings suggested that BDNF signaling plays important paracrine roles during blastocyst development by promoting the development of preimplantation embryos.

Direct Evidence for the Action of Phosphatidylinositol (3,4,5)-Trisphosphate-Mediated Signal Transduction in the 2-Cell Mouse Embryo1

Paf (1-o-alkyl-2-acetyl-sn-gylcero-3-phosphocholine) is a putative autocrine survival factor for the preimplantation embryo. It acts to induce receptor-mediated calcium transients in the early embryo. Inhibitors of 1-o-phosphatidylinositol-3-kinase (PI3kinase), such as wortmannin and LY 294002, blocked these calcium transients, implicating the generation of phosphatidylinositol (3,4,5)-trisphosphate (PIP3) in autocrine signal transduction in the early embryo. Perfusion of the embryo cytoplasm with a blocking antibody to PIP3 inhibited paf-induced calcium transients and hyperpolarization of the membrane potential. Furthermore, direct infusion of PIP3 into the embryo induced a nifedipine (10 micromol/L)- and diltiazem (10 micromol/L)-sensitive calcium current in the 2-cell embryo. PIP3 acts as a docking site on membranes for proteins that contain pleckstrin homology domains, such as the thymoma viral proto-oncogene protein (AKT) and phospholipase C gamma. The 2-cell embryo expressed three genes for AKT (Akt 1-3) and two genes for phospholipase C gamma (Plcg1 and Plcg2), and we confirmed the expression of both AKT and phospholipase C gamma 1 by immunolocalization. Paf induced increased accumulation of serine 473-phosphorylated AKT in the region of the plasma membrane, consistent with its recruitment to membrane PIP3. Inhibitors of PI3kinase, such as LY294002, and of AKT, e.g., deguelin and AKT-inhibitor, reduced zygote development in a dose-dependent manner, and this inhibition was partially reversed by the addition of paf to the culture medium. These results provide the first direct evidence that PIP3 and its responsive signaling pathways act in the 2-cell embryo. Since signal transduction via PI3kinase has important roles in governing the cell survival pathways, these results support the hypothesis that autocrine embryotropins, such as paf, act as survival factors.

Tumor necrosis factor regulation of apoptosis in mouse preimplantation embryos and its antagonism by transforming growth factor alpha/phosphatidylionsitol 3-kinase signaling system

Survival and apoptosis of cells in preimplantation embryos are fundamental for successful pregnancy. Relevant to these processes, tumor necrosis factor (TNF) and transforming growth factor alpha (TGFA) are produced by mammalian oviducts and uteri. In early embryos, TNF induces apoptosis, whereas TGFA could act as a survival factor. Here we investigated the TNF regulation of apoptosis in early mouse embryos and its antagonism by TGFA. TNF receptor superfamily, member 1a mRNA was detectable throughout early embryonic stages, with an increase after the early blastocyst stage, whereas the expression of TNF receptor superfamily, member 1b transcripts were detected only at the expanded blastocyst stage. Although pregnant uteri produced TNF, physiologic levels were low during the preimplantation period. Treatment with TNF inhibited the development of two-cell stage embryos to blastocysts showing decreased proliferation and increased apoptosis both in vitro and in vivo. These detrimental effects of TNF on early embryo development and survival were blocked by a neutralizing anti-TNF antibody. In addition to the death receptor-mediated pathway, TNF-induced apoptosis was further mediated by disruption of mitochondrial functions, characterized by release of cytochrome c and activation of caspase 9. The proapoptotic effects of TNF in blastocysts were counteracted by cotreatment with TGFA. The antagonistic effect of TGFA on TNF-induced apoptosis was blocked by phosphatidylionsitol 3-kinase (PI3K) inhibitors. The present findings demonstrate the stage-selective susceptibility to the apoptosis-inducing effect of TNF in mouse preimplantation embryos and that the TGFA/PI3K signaling system has an important role in the control of TNF-induced apoptosis in blastocysts.

Glucose utilization and the PI3-K pathway: mechanisms for cell survival in preimplantation embryos

The maintenance of optimal glucose utilization during the preimplantation period is critical for embryo survival. A decrease in glucose transport during preimplantation development has been linked to the early steps of programmed cell death in these embryos. Decreased glucose transport is not thought to be simply a consequence of cell death, rather it is thought to be a trigger that can initiate the apoptotic cascade. Extensive apoptosis during the preimplantation period may manifest later in pregnancy as a malformation – or miscarriage, if cell loss is excessive. Phosphatidylinositol 3-kinase (PI3-K) is a known regulator of a number of physiologic responses including cellular proliferation, growth, and survival as well as glucose metabolism. Studies performed in other cell systems have demonstrated that the PI3-K pathway plays a critical role in maintaining glucose transport and metabolism. This review will present the current evidence that suggests that PI3-K is vital for preimplantation embryo survival and development. In addition, data demonstrating that PI3-K activity is important for glucose metabolism during this early developmental period will be discussed.

Phosphatidylinositol 3-kinase activity is critical for glucose metabolism and embryo survival in murine blastocysts

The phosphatidylinositol 3-kinase (PI3K) signal transduction pathway is a well known mediator of cell growth, proliferation, and survival signals. Whereas the expression and function of this pathway has been documented during mammalian development, evidence demonstrating the physiologic importance of this pathway in murine preimplantation embryos is beginning to emerge. This study demonstrates that inhibition of the PI3K pathway leads to the induction of apoptosis in both murine blastocysts and trophoblast stem cells. The apoptosis induced in both model systems correlates with a decrease in the expression of the glucose transporter GLUT1 at the plasma membrane. In addition, blastocysts cultured in the presence of the PI3K inhibitor LY-294002 display a decrease in both 2-deoxyglucose uptake and hexokinase activity as compared with control blastocysts. To determine the impact of PI3K inhibition on pregnancy outcome, embryo transfer experiments were performed. Blastocysts cultured in the presence of LY-294002 demonstrate a dramatic increase in fetal resorptions as compared with control embryos. Finally, we demonstrate that impairment of glucose metabolism via iodoacetate, a glyceraldehyde-3-phosphate dehydrogenase inhibitor, is sufficient to induce apoptosis in both blastocysts and trophoblast stem cells. Moreover, blastocysts treated with iodoacetate result in poor pregnancy outcome as determined by embryo transfer experiments. Taken together these data demonstrate the critical importance of the PI3K pathway in preimplantation embryo survival and pregnancy outcome and further emphasize the importance of glucose utilization and metabolism in cell survival pathways.