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

Neurotrophins: are they involved in immune tolerance in pregnancy?

In this review, an attempt was made to substantiate the possibility for neurotrophins to be involved in the development of immune tolerance based on data accumulated on neurotrophin content and receptor expression in the trophoblast and immune cells, in particular, in natural killer cells. Numerous research results are reviewed to show that the expression and localization of neurotrophins along with their high-affinity tyrosine kinase receptors and low-affinity p75NTR receptor in the mother-placenta-fetus system indicate the important role of neurotrophins as binding molecules in regulating the crosstalk between the nervous, endocrine, and immune systems in pregnancy. An imbalance between these systems can occur with tumor growth and pathological processes observed in pregnancy complications and fetal development anomalies.

Hydroxysafflor Yellow A Attenuates Neuron Damage by Suppressing the Lipopolysaccharide-Induced TLR4 Pathway in Activated Microglial Cells

Microglia activation initiates a neurological deficit cascade that contributes to substantial neuronal damage and impairment following ischemia stroke. Toll-like receptor 4 (TLR4) has been demonstrated to play a critical role in this cascade. In the current study, we tested the hypothesis that hydroxysafflor yellow A (HSYA), an active ingredient extracted from Flos Carthami tinctorii, alleviated inflammatory damage, and mediated neurotrophic effects in neurons by inducing the TLR4 pathway in microglia. A non-contact Transwell co-culture system comprised microglia and neurons was treated with HSYA followed by a 1 mg/mL lipopolysaccharide (LPS) stimulation. The microglia were activated prior to neuronal apoptosis, which were induced by increasing TLR4 expression in the activated microglia. However, HSYA suppressed TLR4 expression in the activated microglia, resulting in less neuronal damage at the early stage of LPS stimulation. Western blot analysis and immunofluorescence indicated that dose-dependently HSYA down-regulated TLR4-induced downstream effectors myeloid differentiation factor 88 (MyD88), nuclear factor kappa b (NF-κB), and the mitogen-activated protein kinases (MAPK)-regulated proteins c-Jun NH2-terminal protein kinase (JNK), protein kinase (ERK) 1/2 (ERK1/2), p38 MAPK (p38), as well as the LPS-induced inflammatory cytokine release. However, HSYA up-regulated brain-derived neurotrophic factor (BDNF) expression. Our data suggest that HSYA could exert neurotrophic and anti-inflammatory functions in response to LPS stimulation by inhibiting TLR4 pathway-mediated signaling.

Dysregulated activation of c-Src in gestational trophoblastic disease contributes to its aggressive progression

INTRODUCTION

Gestational trophoblastic disease (GTD) is a heterogeneous group of pregnancy-related disorders. Hydatidiform mole (HM) is the most common type of GTD, whereas gestational choriocarcinoma is the most aggressive. Non-receptor tyrosine kinase c-Src contributes to the transformation to a malignant phenotype in various cancers. However, the role of c-Src in the pathogenesis of GTD remains largely unknown.

METHODS

The expression level of phosphorylated c-Src was determined by immunohistochemistry and Western blotting assay. JAR and JEG-3 cells were treated with hCG, specific c-Src inhibitor saracatinib and PP2, and PKA specific inhibitor, PKI. Cell growth rate and cell migration/invasion ability was determined by cell proliferation and transwell assays respectively.

RESULTS

c-Src was highly activated in HM tissues and choriocarcinoma cells (JAR and JEG-3). c-Src was activated by hCG in a time and concentration-dependent manner, which was abrogated by specific c-Src and PKA inhibitors. Inhibition of c-Src activity in JAR and JEG-3 cells by saracatinib leaded to a decrease in the rate of cell growth and cell migration/invasion ability. Furthermore, inhibition of c-Src phosphorylation induced cell cycle arrest and reduced expressions of cyclin A2, cyclin B1, cyclin E1, FOXD3 and NANOG. Moreover, inhibition of c-Src activity resulted in decreased p-FAK(Tyr397) phosphorylation.

DISCUSSION AND CONCLUSION

Our findings indicate an important role of c-Src in the pathogenesis of GTD, and we propose that c-Src inhibitors are potential adjuvant chemotherapeutic drugs for the treatment of GTD.

Levels of brain derived neurotrophic factors across gestation in women with preeclampsia

Preeclampsia (PE) is a major pregnancy complication of placental origin which leads to adverse pregnancy outcome. Brain derived neurotrophic factor (BDNF) is suggested to promote trophoblast growth and regulate placental and fetal development. This study for the first time examines the levels of maternal plasma BDNF at various time points during gestation, cord plasma and placental BDNF levels and their association with birth outcome in women with PE. Normotensive control (NC) women (n=89) and women with PE (n=61) were followed at three different time points [16-20 weeks (T1), 26-30 weeks (T2) and at delivery (T3)]. Maternal blood at all time points and cord blood was collected. Results indicate that maternal BDNF levels at T1 (p=0.050) and T3 (p=0.025) were lower in women with PE than in NC women. Cord BDNF levels at delivery in women with PE were lower (p=0.032) than those in NC women. Placental BDNF gene expression was also lower (p=0.0082) in women with PE than in NC women. Our data suggests that BDNF plays an important role in the development of the materno-fetal-placental unit during pregnancy. Alteration in the levels of BDNF during pregnancy may be associated with an abnormal development of the placenta resulting in PE.

Suppression of choriocarcinoma invasion and metastasis following blockade of BDNF/TrkB signaling

Brain-derived neurotrophic factor (BDNF) acts through its cognate receptor tyrosine kinase-B (TrkB) to regulate diverse physiological functions in reproductive and other tissues. In normal and malignant trophoblastic cells, the BDNF/TrkB signaling promotes cell growth. Due to the highly malignant nature of choriocarcinoma, we investigated possible involvement of this system in choriocarcinoma cell invasion and metastasis. We demonstrated that treatment of cultured choriocarcinoma cells, known to express both BDNF and TrkB, with a soluble TrkB ectodomain or a Trk receptor inhibitor K252a suppressed cell invasion accompanied with decreased expression of matrix metalloproteinase-2, a cell invasion marker. In vivo studies using a tumor xenograft model in athymic nude mice further showed inhibition of cell invasion from tumors to surrounding tissues following the suppression of endogenous TrkB signaling. For an in vivo model of choriocarcinoma metastasis, we performed intravenous injections of JAR cells expressing firefly luciferase into severe combined immunodeficiency (SCID) mice. Treatment with K252a inhibited metastasis of tumors to distant organs. In vivo K252a treatment also suppressed metastatic tumor growth as reflected by decreased cell proliferation and increased apoptosis and caspases-3/7 activities, together with reduced tissue levels of a tumor marker, human chorionic gonadotropin-β. In vivo suppression of TrkB signaling also led to decreased expression of angiogenic markers in metastatic tumor, including cluster of differentiation 31 and vascular endothelial growth factor A. Our findings suggested essential autocrine/paracrine roles of the BDNF/TrkB signaling system in choriocarcinoma invasion and metastasis. Inhibition of this signaling could serve as the basis to develop a novel therapy for patients with choriocarcinoma.