Matrix metalloproteinases, prostaglandins and endothelins: paracrine regulators of implantation

Effects of cigarette smoke extracts on cell cycle, cell migration and endocrine activity in human placental cells

Maternal smoking during pregnancy is known to be related to adverse pregnancy results associated with trophoblast proliferation and cell cycle progression. Moreover, many previous studies have shown that cigarette smoke is correlated with human chorionic gonadotropin beta (hCG-β) subunit produced from syncytiotrophoblasts during pregnancy. Thus, we further investigated whether cigarette smoke extract (CSE) affects the cell proliferation, migration and endocrine hormone activity of JEG-3 human placental cancer cells. JEG-3 cell proliferation was significantly reduced by all CSEs in a concentration-dependent manner. Moreover, CSEs decreased proliferating cell nuclear antigen (PCNA) levels in JEG-3 cells in Western blot. Increased migration or invasion ability of JEG-3 cells following CSE treatment was also confirmed by a scratch or fibronectin invasion assay in vitro. Additionally, protein levels of E-cadherin as an epithelial maker were down-regulated, while the mesenchymal markers N-cadherin, snail and slug were up-regulated in a time-dependent manner. The metastasis marker, cathepsin D, was also down-regulated by CSE. Finally, CSEs significantly reduced the expression of hCG-β protein in JEG-3 cells. Overall, these results indicate that exposure of placental cells to CSE deregulates the cell cycle by altering the expression of cell cycle-related proteins and stimulates cell metastatic ability by altering EMT markers and cathepsin D expression. CSE exposure may also decrease hCG-β production as an endocrine marker, implying that cigarette smoke has adverse effects during pregnancy.

Effects of cigarette smoking on reproduction

BACKGROUND Cigarette smoking is associated with lower fecundity rates, adverse reproductive outcomes and a higher risk of IVF failures. Over the last few decades, prevalence of smoking among women of reproductive age has increased. This review focuses on current knowledge of the potential effects of smoke toxicants on all reproductive stages and the consequences of smoke exposure on reproductive functions. METHODS We conducted a systematic review of the scientific literature on the impact of cigarette smoking and smoke constituents on the different stages of reproductive function, including epidemiological, clinical and experimental studies. We attempted to create hypotheses and find explanations for the deleterious effects of cigarette smoke observed in experimental studies. RESULTS Cigarette smoke contains several thousand components (e.g. nicotine, polycyclic aromatic hydrocarbons and cadmium) with diverse effects. Each stage of reproductive function, folliculogenesis, steroidogenesis, embryo transport, endometrial receptivity, endometrial angiogenesis, uterine blood flow and uterine myometrium is a target for cigarette smoke components. The effects of cigarette smoke are dose-dependent and are influenced by the presence of other toxic substances and hormonal status. Individual sensitivity, dose, time and type of exposure also play a role in the impact of smoke constituents on human fertility. CONCLUSIONS All stages of reproductive functions are targets of cigarette smoke toxicants. Further studies are necessary to better understand the deleterious effects of cigarette smoke compounds on the reproductive system in order to improve health care, help to reduce cigarette smoking and provide a better knowledge of the molecular mechanisms involved in reproductive toxicology.

Endothelin-1 down-regulates the expression of vascular endothelial growth factor-A associated with osteoprogenitor proliferation and differentiation

Endothelin-1 (ET-1) is implicated in the signaling between vascular endothelial cells (VECs) and osteoblasts during bone development, remodeling and repair. Vascular endothelial growth factor (VEGF) also plays an important role in these intercellular interactions. Our objectives were to identify which specific VEGF isoforms were produced during osteoblastic proliferation and differentiation and to determine the effects of ET-1 on VEGF mRNA and protein production by osteoblastic cells. Semiquantitative reverse transcription polymerase chain reaction (RT-PCR) and ELISA were used to evaluate VEGF mRNA isoform expression and protein synthesis at different stages of ET-1-induced osteoblastic differentiation in fetal rat calvaria (FRC) osteoblastic cells. Three VEGF mRNA isoforms were identified corresponding to VEGF(120), VEGF(164) and VEGF(188). Predominant isoforms VEGF(120) and VEGF(164) had a bimodal expression that increased in the early proliferation and late mineralization phases. ET-1 stimulated osteoblastic proliferation and differentiation, but surprisingly, ET-1 down-regulated VEGF mRNA and protein expression and sustained the down-regulation over time in long-term cultures. Time course studies showed that ET-1 inhibited VEGF mRNA expression after incubation for 3 h in 7- and 14-day FRC cell cultures. Similarly, ET-1 inhibited VEGF protein secretion by 5.8- and 2.8-fold in 7- and 14-day FRC cells, respectively. VEGF-A protein secretion was inhibited by ET-1 in a dose-dependent manner with a maximal effect at 10(-7) M. This study supports a novel inhibitory role for ET-1 on VEGF synthesis in osteoblastic cells as a feedback mechanism in the temporal and spatial coupling of angiogenesis to bone formation and resorption.

Maternal influences on placental development

Epidemiological evidence suggests that size at birth may affect health in later life. The growth of the fetus may be adversely affected by a suboptimal maternal environment. Understanding placental development and function will help unravel the mechanisms controlling fetal growth. This article poses the problem: how does the maternal environment (uterine or systemic) influence placental development? Critical human placental functions include remodelling maternal uterine spiral arteries to increase the flow of blood to the maternofetal interface, and transferring oxygen and nutrients into the fetal vasculature, all processes involving trophoblast. Gene ablations that affect pregnancy outcome in mice lead to some interesting hypotheses.