Suppression of Protein Phosphatase 2 Differentially Modulates VEGF- and FGF2-Induced Signaling in Ovine Fetoplacental Artery Endothelial Cells

Vascular endothelial growth factor (VEGF) and fibroblast growth factor 2 (FGF2) elicit cellular responses via activation of protein kinases and phosphatases. We have reported that the MEK1/2/ERK1/2 and PI3K/AKT1 pathways are critical for VEGF- and FGF2-stimulated ovine fetoplacental artery endothelial (OFPAE) cell proliferation. We have also shown that protein phosphatase 3 (PPP3) differentially modulates VEGF- and FGF2-stimulated cell proliferation and activation of ERK1/2 and AKT1 in OFPAE cells. Herein, we investigated if protein phosphatase 2 (PPP2) modulated VEGF- and FGF2-induced ERK1/2, AKT1, and p38 MAPK activation and VEGF- and FGF2-stimulated cell proliferation in OFPAE cells. Small interfering RNA (siRNA) specifically targeting human PPP2CA catalytic subunit α (PPP2CA) was used to suppress PPP2CA expression in OFPAE cells. When compared with scrambled siRNA, PPP2CA siRNA decreased (p < 0.05) PPP2CA protein levels (～70%) and activity (～50%) without altering protein levels of PPP3 catalytic subunit α (PPP3CA), nitric oxide synthase 3 (NOS3), ERK1/2, AKT1, and p38 MAPK. FGF2, but not VEGF rapidly (≤5 min) induced p38 MAPK phosphorylation. Suppression of PPP2CA enhanced (p < 0.05) VEGF-induced AKT1, but not ERK1/2 phosphorylation, whereas inhibited (p < 0.05) FGF2-induced ERK1/2 and p38 MAPK and slightly attenuated FGF2-induced AKT1 phosphorylation. Suppression of PPP2CA did not significantly affect VEGF- and FGF2-stimulated OFPAE cell proliferation. Thus, suppression of PPP2CA alone differentially modulated VEGF- and FGF2-induced ERK1/2, AKT1, and p38 MAPK activation, without altering VEGF- and FGF2-stimulated cell proliferation in OFPAE cells. These data also suggest that signaling molecules other than ERK1/2, AKT1, and p38 MAPK are important mediators for VEGF- and FGF2-stimulated OFPAE cell proliferation after PPP2CA suppression.     

Differential activation of multiple signalling pathways dictates eNOS upregulation by FGF2 but not VEGF in placental artery endothelial cells

Fibroblast growth factor (FGF2), but not vascular endothelial growth factor (VEGF), upregulates endothelial nitric oxide synthase (eNOS) protein expression, at least partially, via activation of extracellular signal-regulated kinase 2/1 (ERK2/1) in ovine fetoplacental artery endothelial (oFPAE) cells. Herein we further investigated the temporal effects of FGF2 and VEGF on other signalling pathways including members (Jun N-terminal kinase JNK1/2 and p38MAPK) of mitogen-activated protein kinases (MAPK), phosphatidylinositol-3 kinase/v-akt murine thymoma viral oncogene homologue 1 (PI3K/AKT1), and the tyrosine kinase c-SRC, and examined if either one or more of these pathways play a role in the differential regulation of eNOS by FGF2 and VEGF. We first confirmed that in oFPAE cells, FGF2, but not VEGF, increased eNOS protein. FGF2 stimulated eNOS protein in a time- and concentration-dependent manner, which also depended on cell density. FGF2 provoked sustained (5min to 12h) whereas VEGF only stimulated transient (5min) ERK2/1 phosphorylation. FGF2 was 1.7-fold more potent in stimulating ERK2/1 phosphorylation than VEGF. FGF2 and VEGF only transiently activated JNK1/2 and AKT1 within 5min; however, FGF2 was a stronger stimulus than VEGF. FGF2 and VEGF did not significantly activate p38MAPK at 5min; however, VEGF stimulated p38MAPK phosphorylation at 60min. VEGF but not FGF2 significantly stimulated c-SRC phosphorylation. Inhibitors of MEK-ERK2/1 (PD98059), JNK1/2 (SP600125) and PI3K (wortmannin), but not p38MAPK (SB203580) and SRC (PP2), decreased the FGF2-increased eNOS protein expression. Thus, the FGF2-induced eNOS protein expression requires activation of multiple signalling pathways including ERK2/1, JNK1/2 and PI3K/AKT1. Differences in intensity and temporal patterns of activation of these pathways by FGF2 and VEGF may account for their differential effects on eNOS expression in OFPAE cells.     

SDF-1对卵巢癌细胞增殖和侵袭能力作用的相关通路研究

目的:探讨PI3K/Akt信号通路抑制剂LY294002、MEK通路抑制剂PD98059对基质衍生因子-1(SDF-1)作用下卵巢癌细胞SKOV3的增殖、侵袭能力的影响,初步探讨SDF-1在卵巢癌中的相关作用通路。方法:细胞免疫化学法检测SDF-1不同作用时间及不同作用浓度对卵巢癌细胞中磷酸化Akt(p-Akt)和ERK(p-ERK)表达的影响。选取对数生长期细胞,分别加SDF-1 100ng/ml、CXCR4中和抗体10μg/ml、CXCR4抑制剂AMD3100 1μg/ml、LY294002 50μmol/L、PD98059 50μmol/L。MTT、Transwell细胞侵袭实验检测细胞的增殖、侵袭能力的变化。结果:随着SDF-1作用时间的延长,p-Akt、p-ERK蛋白表达水平增高;Akt、ERK蛋白的最佳活化时间为30min。作用30min时,随着SDF-1作用浓度的增加,p-ERK1、p-Akt蛋白表达水平增高,差异具有统计学意义(P0.05)。SDF-1可明显促进SKOV3细胞的增殖、侵袭能力(P0.05);但加入CXCR4中和抗体、CXCR4抑制剂AMD3100、通路抑制剂PD98059、LY294002后,SKOV3细胞的增殖、侵袭能力无明显变化(P0.05)。结论:SDF-1对卵巢癌SKOV3细胞的增殖、侵袭能力的增强作用可被PI3K/Akt信号通路抑制剂、MEK通路抑制剂所阻断。SDF-1可能通过Ras/ERK信号转导通路、PI3K/Akt信号通路发挥作用。     

Susceptibility to Toxoplasma gondii proliferation in BeWo human trophoblast cells is dose-dependent of macrophage migration inhibitory factor (MIF), via ERK1/2 phosphorylation and prostaglandin E2 production

Introduction

Macrophage migration inhibitory factor (MIF) participates in the immune response to Toxoplasma gondii, triggers ERK1/2 and prostaglandin E₂ (PGE₂) activation, but there is limited information on these mechanisms in human trophoblast. The present study aimed to verify the role of MIF in the ERK1/2 phosphorylation and PGE₂ production, as well as its effect on the susceptibility to T. gondii in BeWo cells.

Methods

BeWo cells were treated with increasing concentrations of recombinant MIF (rMIF) and/or T. gondii-soluble tachyzoite antigen (STAg) and analyzed for ERK1/2 phosphorylation and PGE₂ production by Western blotting and ELISA, respectively. Cells were also treated with increasing concentrations of rMIF, rPGE₂, or ERK1/2 inhibitor and tested for T. gondii proliferation. The supernatants of cells treated with rPGE₂ were assayed for cytokine production by ELISA or CBA.

Results

ERK1/2 phosphorylation and PGE₂ production increased when the cells were treated with low MIF concentrations while the parasitism control occurred only at high MIF concentrations. STAg was unable to change ERK1/2 phosphorylation or PGE₂ release. BeWo cells demonstrated increased T. gondii proliferation and reduced production of pro-inflammatory cytokines when treated with PGE₂, while PD98059 diminished the parasite proliferation.

Discussion

The intracellular mechanisms triggered by MIF are dose-dependent in BeWo cells, and PGE₂ is an important factor for the persistence of T. gondii at the maternal fetal interface.

Conclusion

MIF was unable to control T. gondii infection in BeWo cells at low concentrations since ERK1/2 and PGE₂ expression were activated, demonstrating a critical effect of these mediators favoring parasite proliferation.     

Phosphorylation of JAK2 by serotonin 5-HT (2A) receptor activates both STAT3 and ERK1/2 pathways and increases growth of JEG-3 human placental choriocarcinoma cell

Serotonin 5-HT_2A receptor activation improves viability, increases DNA synthesis and activates JAK2-STAT3 and MEK1/2-ERK1/2 signalling pathways in JEG-3 human trophoblast choriocarcinoma cells. The goal of this study was to characterize the signal transduction cascade involved in 5-HT_2A receptor-induced growth of JEG-3 cells. Selective 5-HT_2A receptor agonist, DOI, induced JEG-3 cell growth was inhibited by the inhibitor of JAK2 (AG490), MEK1/2 (U0126), phospholipase C-β (PLC-β; U73122) and protein kinase C-β (PKC-β; Gö6976)), whereas the selective phosphatidylinositol 3-kinase (PI3K) inhibitor (LY294002) had no effect. Specific inhibitors of PLC-β, PKC-β and Ras (farnesylthiosalicylic acid) inhibit activation of ERK1/2, whereas the PKC-ζ inhibitor GF109203X had no effect. Interestingly, inhibition of JAK2 prevented DOI-induced phosphorylation of ERK1/2 whereas inhibition of ERK1/2 pathway had no effect on DOI-induced activation of STAT3. Taken together, our results demonstrate that both the JAK2-STAT3 and PLC-β-PKC-β-Ras-ERK1/2 signalling pathways are involved in the stimulation of JEG-3 cell growth mediated by DOI. Moreover, this study shows that activation of JAK2 by the 5-HT_2A receptor is essential to activate both STAT3 and ERK1/2 signalling pathways as well as to increase JEG-3 choriocarcinoma cell growth and survival.     

Stromal cell-derived factor 1alpha stimulates human endometrial carcinoma cell growth through the activation of both extracellular signal-regulated kinase 1/2 and Akt

OBJECTIVE: The aim of study was to investigate the proliferative effects of stromal cell-derived factor-1alpha (SDF-1alpha) on endometrial carcinomas cell lines with different estrogen receptors (ER) and PTEN protein profiles. METHODS: MTT assays was used to detect the proliferation of HEC-1A and Ishikawa cells, and Western blotted analysis was used to detect activation of Akt and ERK1/2 in both cell lines after exposure to various concentrations of SDF-1alpha, MAPK-specific inhibitor PD98059 or PI3K-specific inhibitor LY294002. RESULTS: Low concentrations of SDF-1alpha (50 ng/ml) induced proliferation in both cell lines. ERK1/2 was significantly activated for more than 2 h by SDF-1alpha at 20 ng/ml in HEC-1A cells, but not in Ishikawa cells. In contrast, Akt was significantly activated for over 2 h in Ishikawa cells but remained unchanged in HEC-1A cells. High concentrations of SDF-1alpha activated Akt and ERK1/2 pathways in both cell lines in a dose-dependent manner, which was primarily inhibited by LY294002 for pAkt and by PD98059 for pERK 1/2. CONCLUSIONS: SDF-1alpha could stimulate the cell proliferation of endometrial carcinoma with different expression status of ER and PTEN in vitro, likely through the activation of both Akt and ERK1/2 signaling pathways.     

Non-genomic effects of 17β-estradiol in activation of the ERK1/ERK2 pathway induces cell proliferation through upregulation of cyclin D1 expression in bovine artery endothelial cells

Objective. Growing evidence indicates that estrogen's non-genomic effects play important roles in cellular functions and backs up the hypothesis of the existence of a membrane estrogen receptor (mER) in a number of cell types, but little is known about the complementary effects between traditional genomic and novel non-genomic effects of estrogen. The aim of the present study was to explore the non-genomic activation of ERK1/2 mitogen-activated protein kinase (MAPK) by 17β-estradiol (E₂) through mER and its role in cell proliferation.

Methods. On cultured bovine artery endothelial cells (BAECs) we used the [³H]thymidine incorporation assay to evaluate the influence of E₂ on cell proliferation and fluorescence microscopy to show the presence of mER on the cell membrane. Scatchard analysis was performed to identify and characterize the mER on a purified membrane fraction of BAECs.

Results. E₂ upregulated cyclin D1 protein expression and enhanced cell proliferation. Inhibition of the MAPK cascade with PD98059 or of G protein with pertussis toxin (PTX) completely abolished the above effects, while the estrogen receptor antagonist tamoxifen attenuated E₂-dependent upregulation of cyclin D1 and cell proliferation. Accordingly, E₂ rapidly led to ERK1/ERK2 activation, which was prevented by tamoxifen or PTX and was entirely reproduced by membrane-impermeable estradiol–bovine serum albumin conjugate (E₂coBSA). Immunofluorescent staining with E₂coBSA–fluorescein isothiocyanate resulted in a punctuate staining pattern of the plasma membrane and Scatchard analysis of the E₂-binding protein in a purified membrane fraction of BAECs showed that E₂ binds to the membrane fraction with a dissociation constant of 0.2394 nmol/l.

Conclusion. Our findings showed that E₂ induces cell proliferation through upregulation of cyclin D1 via non-genomic activation of the ERK1/ERK2 pathway mediated by mER and G protein.     

CDX1 restricts the invasion of HTR-8/SVneo trophoblast cells by inhibiting MMP-9 expression

Introduction

Pathogenesis of early-onset preeclampsia (PE) is generally recognized by impaired trophoblast invasion of the myometrial arteries, which results in placental insufficiency. Recently, we reported that CDX1 is hypermethylated in the human preeclampsia placenta. However, whether CDX1 participates in trophoblast invasion has not been clearly elucidated.

Methods

We investigated the function of CDX1 in the extravillous trophoblast cell line HTR-8/SVneo using stable transfection of CDX1. Using a CDX1 stable transfected cell line, we determined the cell invasion using a QCM ECMatrix 24-well kit. The cell viability was detected using an MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide) assay. Quantitative RT-PCR and western blotting analyses were performed to examine the changes in the expression of downstream target genes and proteins. To disrupt PI3K/AKT signaling, we used the PI3K inhibitor perifosine.

Results

Cell invasion assays demonstrated that CDX1 restricts trophoblast cell invasiveness. In contrast, quantification of cumulative cell numbers revealed that CDX1 did not affect cell proliferation. Western blotting analysis and quantitative real time PCR demonstrated that MMP-9 expression was reduced, whereas TIMP-1 expression was increased in CDX1-overexpressed cells. However, overexpression of CDX1 did not affect PI3K/AKT signaling in HTR-8/SVneo trophoblast cells. In contrast, CDX1 was regulated by the PI3K/AKT signaling pathway.

Conclusions

Altogether, we found that in trophoblast cells, CDX1 reduced invasion independently of the PI3K/AKT signaling pathway. Furthermore, CDX1 functions in concert with PI3K/AKT signaling to regulate trophoblast invasion. We concluded that CDX1 restricts the invasion of HTR-8/SVneo trophoblast cells by inhibiting MMP-9 expression independently of the PI3K/AKT pathway.     

Hyaluronan up-regulates growth and invasion of trophoblasts in an autocrine manner via PI3K/AKT and MAPK/ERK1/2 pathways in early human pregnancy

Introduction

As one of the key molecules in the extracellular matrix in human conceptus, hyaluronan (HA) has been receiving particular attention. Here, we have investigated the expression and regulation of different molecular weight HA on the biological behaviors of primary human trophoblasts during the first trimester of pregnancy.

Methods

The expression of HA and HA synthetase (HAS) by human first trimester trophoblasts was analyzed in placentae from normal pregnancy or miscarriage by immunochemistry and real-time RT-PCR, respectively. ELISA was used to measure the secretion of HA by primary trophoblasts. The effects of HA on the proliferation, apoptosis and invasiveness of trophoblasts were examined. We also investigated the signaling pathways involved in HA activation in human trophoblasts.

Results

The higher HAS2 expression and HA secretion were observed in normal villi than that of miscarriage, and the primary trophoblasts secreted HA continuously. High molecular weight HA (HMW-HA) and medium molecular weight HA (MMW-HA) promoted proliferation and invasiveness while inhibited apoptosis of trophoblasts. However, low molecular weight HA (LMW-HA) had no obvious effect on the growth or invasiveness of human trophoblasts. In addition, HMW-HA showed more efficiently than MMW-HA on the growth while MMW-HA displayed a more obvious effect on the invasiveness of trophoblasts than HMW-HA. HMW-HA activated PI3K/AKT and MAPK/ERK1/2 signaling pathways in trophoblasts. Blocking PI3K/AKT or MAPK/ERK1/2 signaling inhibited the HA-upregulated growth and invasiveness of human trophoblasts.

Conclusion

Our results suggest that higher level and greater molecular mass of HA can promote trophoblast growth and invasion in an autocrine manner, which was beneficial to placentation and maintenance of human early pregnancy.     

Similar expression to FGF (Sef) reduces endometrial adenocarcinoma cells proliferation via inhibiting fibroblast growth factor 2-mediated MAPK/ERK signaling pathway

Objective

Fibroblast growth factors (FGF) axis, and in particular FGF2 axis, is an important mitogenic stimulus in endometrial carcinogenesis. hSef is a key inhibitory regulator of FGF signaling and aberrant hSef expression is reported to be present in various human carcinomas. The objective of this study was to investigate the role of hSef in the growth and proliferation of endometrial adenocarcinoma cells and to explore the mechanism that may be involved.

Methods

Using western blot analysis, we determined the expression of hSef in Ishikawa cells under different conditions. Using luciferase reporter assays and western blot analysis, we detected the effect of hSef on MAPK/ERK-mediated FGF2 signaling. Using MTT, cell counting and colony formation assays, we analyzed the growth and proliferation of Ishikawa cells under different conditions.

Results

We found that the hSef expression was positively regulated by FGF2-induced MAPK/ERK signaling and inversely, hSef expression efficiently inhibited the activity of FGF2-induced MAPK/ERK signaling, indicating the presence of hSef-mediated negative feedback mechanism for FGF signaling in endometrial cancer cells. In addition, we found that MAPK/ERK signaling was essential for the growth and proliferation of endometrial cancer cells in vitro, and hSef expression significantly reduced the cell proliferation.

Conclusions

hSef expression can inhibit the growth and proliferation of endometrial cancer cells via acting on the FGF2/MAPK/ERK signaling.     

Non-genomic effects of 17beta-estradiol in activation of the ERK1/ERK2 pathway induces cell proliferation through upregulation of cyclin D1 expression in bovine artery endothelial cells.

OBJECTIVE: Growing evidence indicates that estrogen's non-genomic effects play important roles in cellular functions and backs up the hypothesis of the existence of a membrane estrogen receptor (mER) in a number of cell types, but little is known about the complementary effects between traditional genomic and novel non-genomic effects of estrogen. The aim of the present study was to explore the non-genomic activation of ERK1/2 mitogen-activated protein kinase (MAPK) by 17beta-estradiol (E(2)) through mER and its role in cell proliferation. METHODS: On cultured bovine artery endothelial cells (BAECs) we used the [(3)H]thymidine incorporation assay to evaluate the influence of E(2) on cell proliferation and fluorescence microscopy to show the presence of mER on the cell membrane. Scatchard analysis was performed to identify and characterize the mER on a purified membrane fraction of BAECs. RESULTS: E(2) upregulated cyclin D1 protein expression and enhanced cell proliferation. Inhibition of the MAPK cascade with PD98059 or of G protein with pertussis toxin (PTX) completely abolished the above effects, while the estrogen receptor antagonist tamoxifen attenuated E(2)-dependent upregulation of cyclin D1 and cell proliferation. Accordingly, E(2) rapidly led to ERK1/ERK2 activation, which was prevented by tamoxifen or PTX and was entirely reproduced by membrane-impermeable estradiol-bovine serum albumin conjugate (E(2)coBSA). Immunofluorescent staining with E(2)coBSA-fluorescein isothiocyanate resulted in a punctuate staining pattern of the plasma membrane and Scatchard analysis of the E(2)-binding protein in a purified membrane fraction of BAECs showed that E(2) binds to the membrane fraction with a dissociation constant of 0.2394 nmol/l. CONCLUSION: Our findings showed that E(2) induces cell proliferation through upregulation of cyclin D1 via non-genomic activation of the ERK1/ERK2 pathway mediated by mER and G protein.     

AMPK/ERK信号通路在脂联素抑制子宫内膜癌细胞增殖中的作用

目的:探讨脂联素对子宫内膜癌细胞增殖的抑制作用及AMPK/ERK信号传导通路的有关机制。方法:以10μg/ml脂联素作用子宫内膜癌Ishikawa3-H-12细胞0～60min,Western blot检测脂联素作用不同时间后细胞AMPK及ERK的磷酸化程度。脂联素作用12,24h后,分别采用RT-PCR和Western blot检测Cyclin D1 mRNA和蛋白水平。脂联素作用48h,MTT法检测细胞增殖。结果:脂联素以时间依赖方式诱导子宫内膜癌细胞AMPK活化,脂联素作用5min后明显活化,并维持至30min(F=22.749,P=0.000),AMPK抑制剂复合物C可明显抑制脂联素诱导的细胞AMPK活化。脂联素以时间依赖模式抑制子宫内膜癌细胞ERK活化,作用5min ERK活化明显受抑制,并维持至少60min(F=13.802,P=0.000),复合物C明显阻断脂联素诱导的细胞ERK活性抑制。脂联素明显抑制Cyclin D1 mRNA转录和蛋白表达(P=0.003,P=0.000),复合物C明显阻断脂联素对细胞Cyclin D1 mRNA转录和蛋白表达的抑制作用(P=0.006,P=0.000)。脂联素明显抑制细胞增殖(P=0.001),复合物C明显阻断脂联素对细胞的抑制作用(P=0.002)。结论:脂联素可能通过AMPK/ERK/Cyclin D1途径抑制子宫内膜癌细胞增殖。     

抑制长链非编码RNA FAL1表达对上皮性卵巢癌细胞生物学行为的影响及其分子机制

目的：探索上皮性卵巢癌细胞与正常人卵巢细胞中长链非编码RNA（lncRNA） FAL1的表达差异及沉默卵巢癌细胞株SKVO3中lncRNA FAL1的表达对卵巢癌细胞侵袭、迁移及凋亡的影响。方法：利用实时荧光定量聚合酶链反应（qRT-PCR）技术检测组织中lncRNA FAL1表达水平;设计并合成FAL1-siRNA引物序列转染SKVO3,通过细胞划痕试验检测卵巢癌细胞的迁移能力,Transwell侵袭实验检测卵巢癌细胞的侵袭能力,流式细胞术检测卵巢癌细胞的凋亡,蛋白质印迹（Western blotting）检测磷酸化细胞外信号调节蛋白激酶1/2（p-ERK1/2）和磷酸化丝裂原细胞外激酶1/2（p-MEK1/2）蛋白的表达水平。结果：lncRNA FAL1在卵巢癌组织中的表达高于正常卵巢组织[（15.04±2.24） vs. （2.93±0.39）,P＜0.05]。沉默lncRNA FAL1的表达后,卵巢癌细胞的凋亡能力显著增强[（18.38±0.73）% vs. （2.86±0.09）%,P＜0.05],而卵巢癌细胞迁移、侵袭能力均降低[（6.68±1.49）μm vs. （12.85±2.56）μm,（25.80±2.59）个 vs. （145.6±5.23）个,均P＜0.05],MEK/ERK通路MEK1/2和ERK1/2蛋白磷酸化水平明显降低（P＜0.05）。结论：lncRNA FAL1通过激活MEK/ERK通路影响上皮性卵巢癌细胞的侵袭、迁移及凋亡,其表达异常增高可能是卵巢癌发生发展的重要分子机制。     

三氧化二砷对卵巢癌细胞的生长及化疗敏感性的影响

目的:研究三氧化二砷(As2O3)对人卵巢癌COC1细胞顺铂(cDDP)化疗敏感性的影响,As2O3与cDDP联合作用的效应以及As2O3对COC1细胞的生长抑制效应及机制。方法:四甲基偶氮唑蓝(MTT)比色法检测不同浓度As2O3、cDDP作用72h对卵巢癌细胞生长的抑制作用,As2O3对顺铂化疗敏感性的影响及两药联合作用的效应。逆转录聚合酶链反应(RT-PCR)和免疫印迹技术(Western blot)分别检测PIK3CA mRNA和AKT、ERK、MMP-2蛋白表达的变化。结果:单独应用As2O3或cDDP和联合用药时卵巢癌COC1细胞生长均受到抑制,并呈浓度依赖关系,联合用药组抑制率明显高于单独用药组(P<0.05);0.08~0.15μmol/L As2O3无明显细胞毒性,不能提高COC1细胞对顺铂的敏感性。各浓度(1、3、8、16μmol/L)As2O3作用24h可以下调AKT、MMP-2蛋白水平(P<0.05),并呈浓度依赖效应,但对ERK蛋白的表达无显著影响。0.5、1、2、4μmol/L As2O3作用4h,PIK3CA mRNA表达分别降低45.03%、53.05%、61.67%和72.91%(P<0.05)。结论:As2O3抑制COC1细胞增殖具有浓度依赖性,与顺铂联用有相加效应,可能与As2O3下调PIK3CA mRNA、AKT、MMP-2蛋白水平等有关。     

Modulation of expression of 17-Hydroxylase/17,20 lyase (CYP17) and P450 aromatase (CYP19) by inhibition of MEK1 in a human ovarian granulosa-like tumor cell line

The differential steroid production in the theca and granulosa cells in ovary are resulted from unique enzyme expression profiles. Among them, c-fos, a downstream target of mitogen and extracellular signal-regulated kinases (MEK/ERK) signaling, takes part in this compartment. In this study, we investigated the effect of c-fos on the steady-state levels of CYP17 and CYP19 in human ovarian granulosa-like tumor cell line (KGN) by inhibiting MEK/ERK pathway with PD98059. As a result, our finding demonstrated the distinct distribution patterns of CYP17 and CYP19 in KGN. Moreover, the MEK/ERK pathway functions to inhibit the production of CYP17, while enhance the production of CYP19 in granulosa cells, probably involving a c-fos-dependent mechanism. In conclusion, factors such as c-fos may play a crucial role in the down-regulation of CYP17 and up-regulation of CYP19 in granulosa cells, thereby suppressing androstenedione synthesis.     

缺氧通过TrkB抑制人滋养细胞系HTR-8/SVneo细胞增殖和侵袭

目的:探讨缺氧对人滋养细胞系HTR-8/SVneo细胞增殖和侵袭的影响及可能的分子机制。方法:将人滋养细胞系HTR-8/SVneo细胞分为缺氧培养(实验组)和常氧培养(对照组),培养48h后,采用CCK8法检测细胞增殖能力,采用Transwell实验评估细胞侵袭能力;采用RT-PCR和Western blot法分别检测HIF-1αmRNA、p-TrkB、TrkB、p-Akt和Akt表达。结果:缺氧处理显著抑制了HTR-8/SVneo细胞的增殖和侵袭能力(P0.05);48h的缺氧处理降低了HIF-1αmRNA表达;缺氧处理48h后,p-TrkB表达显著减少(P0.05);同时Akt的磷酸化水平明显被抑制(P0.05)。结论:长时间持续缺氧通过抑制HTR-8/SVneo细胞中TrkB的活化,进而抑制PI3K/Akt通路的激活来抑制人滋养细胞的增殖和侵袭。     

Neutral endopeptidase/CD10 expression during phorbol ester-induced differentiation of choriocarcinoma cells through the protein kinase C- and extracellular signal-regulated kinase-dependent signalling pathway

Neutral endopeptidase 24.11 (NEP) is identical to CD10, which is a differentiation antigen for early B-lymphoid progenitors in the B-cell differentiation pathway. This ectoenzyme is known to have a key role in the control of growth, differentiation, and signal transduction of many cellular systems by regulating bioactive peptides and cytokines. Recently, we demonstrated that NEP/CD10 is upregulated during forskolin-induced choriocarcinoma cell differentiation, suggesting that NEP/CD10 is a trophoblast differentiation marker. The purpose of this study was to clarify the enhancement of NEP/CD10 expression and its signal transduction pathway during phorbol ester (PMA)-induced differentiation of BeWo choriocarcinoma cells. PMA-induced differentiation of BeWo cells was confirmed by morphological change and human chorionic gonadotropin (hCG) secretion, which was completely blocked by a protein kinase C (PKC) inhibitor, Bisindolylmaleimide I (Bis I). On immunoblot analysis, PMA enhanced NEP/CD10 expression in a dose- and time-dependent manner, which was completely abolished by Bis I and a mitogen-activated protein kinase (MAPK) kinase (MEK) inhibitor, PD98059. PMA also induced phosphorylation of p44/p42 extracellular signal-regulated kinases (ERK) 1 and 2. These observations indicated that activation of PKC by PMA induced differentiation of BeWo cells, and that PMA activated MAPK/ERK, which resulted in the enhancement of NEP/CD10 expression. Furthermore, immunocytochemical analysis showed that NEP/CD10 expression was detected on the membranes of PMA-treated differentiated BeWo cells. In summary, we demonstrated that NEP/CD10 was enhanced during PMA-induced differentiation of BeWo choriocarcinoma cells through a PKC-dependent MEK/ERK signalling pathway. Our findings also suggest that NEP/CD10 may play a functional role in the process of trophoblast differentiation.     

STAT3-mediated constitutive expression of SOCS3 in an undifferentiated rat trophoblast-like cell line

In the trophoblast, constitutive expression of SOCS3 is important for the negative regulation of trophoblast giant cell differentiation. In this study, we analyzed the signaling pathway regulating the constitutive SOCS3 expression in undifferentiated Rcho-1 cells, which were derived from rat choriocarcinoma and consist of trophoblast stem cells that are capable of differentiating to trophoblast giant cells in vitro. PD98059, an MEK inhibitor, repressed the SOCS3 expression but AG490, a JAK2 inhibitor, did not. Promoter deletion analysis revealed that the STAT response element (SRE) in the SOCS3 promoter is necessary for the promoter activity. Overexpression of STAT3 increased the SOCS3 promoter activity, whereas expression of dominant-negative STAT3 reduced it. Constitutive STAT3 tyrosine phosphorylation that was not inhibited by either AG490 or PD98059 was demonstrated. Electrophoretic mobility shift assays showed the existence of a protein that bound to SRE and was supershifted with STAT3 antibody. This binding reaction was inhibited by neither AG490 nor PD98059. These findings imply that the ERK/MAPK pathway and STAT3 are involved in the constitutive activation of SOCS3 in undifferentiated Rcho-1 cells. Moreover, they indicate that the constitutive STAT3 tyrosine phosphorylation and the DNA binding activity of STAT3 do not depend on the ERK/MAPK or JAK kinase pathway. These results suggest that a trophoblast-specific STAT3 activation pathway is important for the regulation of giant cell differentiation.     

Kisspeptin-10 inhibits cell migration in vitro via a receptor-GSK3 beta-FAK feedback loop in HTR8SVneo cells

Kisspeptin inhibits cancer cell metastasis and placental trophoblast cell migration. Kisspeptin gene expression in the placenta and circulating kisspeptin levels change during normal pregnancy and they are altered in preeclampsia. We therefore assessed the effect of kisspeptin-10 on the in vitro migration of a human placental cell line derived from first trimester extravillious trophoblasts (HTR8SVneo). HTR8SVneo cells specifically bound 125I-Kisspeptin-10 but kisspeptin-10 did not induce inositol phosphate production. Cell migration was inhibited by kisspeptin-10 with a maximal inhibition at 100nM. The signaling pathways involved in inhibition of cell migration were examined. Treatment with kisspeptin-10 elicited phosphorylation of GSK3 beta at Ser9 (which inhibits activity), with a 3-fold increase at 5 min. Transient phosphorylation of ERK1/2 and p38MAPK peaked at 10min. Phosphorylation of focal adhesion kinase (FAK) at Tyr925 increased 3-fold at 10 min. Inhibition of GSK3 beta correlated with release of beta-catenin into the cytoplasm. These signaling events were differentially blocked by inhibitors of G(q/11), Src, EGFR, PI(3)K, PKC and MEK. The data suggest that kisspeptin/GPR54 EGF-receptor transactivation leads to phosphorylation of ERK1/2, causing activation of p90rsk which in turn inhibits GSK3 beta via Ser9 phosphorylation. Inactivation of GSK3 beta results in release of beta-catenin into the cytoplasm, affecting cell-cell adhesion and Tyr925 phosphorylation of FAK, which increases phosphorylation of ERK1/2 via RAS/Raf-1 creating a feedback loop to enhance the effects on migration. These findings indicate that kisspeptin-10 inhibits the migration of human placental trophoblast-derived HTR8SVneo cells by stimulating complex ERK1/2-p90rsk-GSK3 beta-FAK feedback interactions.