Ratana Lim

Neutrophil gelatinase‐associated lipocalin (NGAL) an early‐screening biomarker for ovarian cancer: NGAL is associated with epidermal growth factor‐induced epithelio‐mesenchymal transition

The expression of neutrophil gelatinase‐associated lipocalin (NGAL) has been shown to be upregulated in ovarian cancer cells. In this study, we report that the expression of immunoreactive NGAL (irNGAL) in ovarian tumors changes with disease grade and that this change is reflected in the concentration of NGAL in peripheral blood. A total of 59 ovarian tissues including normal, benign, borderline malignant and grades 1, 2 and 3 malignant were analyzed using immunohistochemistry. irNGAL was not present in normal ovaries and the NGAL expression was weak to moderate in benign tissues. Both borderline and grade 1 tumors displayed the highest amount of NGAL expression with moderate to strong staining, whereas in grade 2 and 3 tumors, the extent of staining was significantly less (p < 0.01) and staining intensity was weak to moderate. Staining in all cases was confined to the epithelium. NGAL expression was analyzed by ELISA in 62 serum specimens from normal and different grades of cancer patients. Compared to control samples, the NGAL concentration was 2 and 2.6‐fold higher in the serum of patients with benign tumors and cancer patients with grade 1 tumors (p < 0.05) and that result was consistent with the expression of NGAL performed by Western blot. NGAL expression was evaluated by Western blot in an immortalized normal ovarian cell line (IOSE29) as well as ovarian cancer cell lines. Moderate to strong expression of NGAL was observed in epithelial ovarian cancer cell lines SKOV3 and OVCA433 while no expression of NGAL was evident in normal IOSE29 and mesenchyme‐like OVHS1, PEO.36 and HEY cell lines. NGAL expression was downregulated in ovarian cancer cell lines undergoing epithelio‐mesenchymal transition (EMT) induced by epidermal growth factor (EGF). Downregulation of NGAL expression correlated with the upregulation of vimentin expression, enhanced cell dispersion and downregulation of E‐cadherin expression, some of the hallmarks of EMT. EGF‐induced EMT phenotypes were inhibited in the presence of AG1478, an inhibitor of EGF receptor tyrosine kinase activity. These data indicate that NGAL may be a good marker to monitor changes of benign to premalignant and malignant ovarian tumors and that the molecule may be involved in the progression of epithelial ovarian malignancies.

SIRT1 Is a Novel Regulator of Key Pathways of Human Labor

Human sirtuin (SIRT) 1 and SIRT2, which possess nicotinamide adenosine dinucleotide (NAD+)-dependent deacetylase activity, exhibit anti-inflammatory actions. However, there are no data available on SIRT1 and SIRT2 expression and regulation in human intrauterine tissues. Thus, the aim of this study was to characterize the localization and expression of SIRT1 and SIRT2 in 1) placenta and fetal membranes before and after term spontaneous labor onset, 2) prelabor fetal membranes from the supracervical site (SCS) and a distal site (DS), and 3) in response to proinflammatory stimuli. Further, the effect of SIRT activation using resveratrol and SRT1720 on prolabor mediators was also assessed. SIRT1 and SIRT2 were localized in the syncytiotrophoblast layer and the cytotrophoblasts of the placenta, amnion epithelium, trophoblast layer of the chorion, and decidual cells. Additionally, SIRT2 was found within the endothelial walls of placental vessels. SIRT2, but not SIRT1, staining was significantly lower in amnion and chorion obtained from the SCS compared to a DS. On the other hand, SIRT1, but not SIRT2, gene and/or protein expression was significantly lower in placenta, amnion, and chorion obtained after labor compared to prelabor. SIRT1 expression, but not SIRT2, was down-regulated by lipopolysaccharide (LPS) and proinflammatory cytokines TNF and IL1B. The SIRT1 activators resveratrol and SRT1720 significantly decreased LPS-induced TNF, IL6, and IL8 gene expression and release and PTGS2 mRNA expression and resultant prostaglandin (PG) E2 and PGF2α release from human gestational tissues. In conclusion, SIRT1 possesses anti-inflammatory actions and thus may play a role in regulating pregnancy and parturition.

Peroxisome proliferator-activated receptors are altered in pathologies of the human placenta: Gestational diabetes mellitus, intrauterine growth restriction and preeclampsia

BACKGROUND Common complications of pregnancy arise in part from dysfunctional placental development, and include gestational diabetes mellitus (GDM), intrauterine growth restriction (IUGR) and preeclampsia (PE). Peroxisome proliferator-activated receptors (PPARs), and their partner retinoid X receptor a (RXRalpha), mediate trophoblast differentiation and thus may offer insight into the pathophysiology of these diseases. METHODS Human placentae were obtained from women at term with GDM and were compared to uncomplicated term placentae. Placentae from women who delivered preterm with IUGR, PE or co-existing PE and IUGR were compared to matched controls. Quantitative RT-PCR and Western blotting were used to examine mRNA and protein expression of PPARalpha, PPARdelta, PPARgamma and RXRalpha. DNA binding activity of PPAR isoforms were measured in nuclear protein extracts. RESULTS GDM was associated with significantly lower placental PPARgamma mRNA and protein, PPARalpha protein and RXRalpha protein expression, while PPAR DNA binding activity remained unchanged. Placentae from women with PE did not demonstrate any changes in mRNA or protein expression or PPAR DNA binding activity, while IUGR/PE placenta showed significant increases in PPARalpha protein, PPARgamma mRNA and protein and RXRalpha mRNA and protein expression. Significantly elevated protein expression of PPARalpha and RXRalpha were associated with IUGR placentae. IUGR and IUGR/PE placentae had significantly higher PPARgamma DNA binding activity compared to controls. CONCLUSIONS The data presented herein suggest that PPARs may be involved in the pathophysiology of GDM, PE and IUGR.

Dietary phytophenols curcumin, naringenin and apigenin reduce infection-induced inflammatory and contractile pathways in human placenta, foetal membranes and myometrium

A tenet of contemporary obstetrics is that a significant proportion of preterm births involve bacterial infection. Bacterial endotoxin induces pro-inflammatory cytokines, prostaglandins and proteases via the pro-inflammatory pathway nuclear factor-κB (NF-κB), which plays a key role in initiating uterine contractions and rupture of foetal membranes. In non-gestational tissues, the phytophenols curcumin, naringenin and apigenin exert anti-inflammatory properties via inhibition of NF-κB. The aim of this study was to determine whether these treatments regulate pro-inflammatory and pro-labour mediators in human gestational tissues. Placenta, foetal membranes and myometrium were treated with curcumin, naringenin and apigenin in the presence of lipopolysaccharide (LPS) or interleukin (IL)-1β. In placenta and foetal membranes, all treatments significantly reduced LPS-stimulated release and gene expression of pro-inflammatory cytokines IL-6 and IL-8; placenta decreased cyclooxygenase (COX-2) mRNA expression, subsequent release of prostaglandins PGE2 and PGF2α and expression and activity of matrix-degrading enzyme matrix metalloproteinase (MMP)-9. In myometrial cells, all treatments attenuated IL-1β-induced COX-2 expression, release of PGE2 and PGF2α and expression and activity of MMP-9. Although naringenin significantly attenuated IL-1β-induced IL-6 and IL-8 mRNA expression and release, there was no effect of curcumin and apigenin. LPS-stimulated release of 8-isoprostane, a marker of oxidative stress, was attenuated by all treatments. NF-κB p65 DNA-binding activity was also decreased using these treatments. In conclusion, curcumin, naringenin and apigenin exert anti-inflammatory properties in human gestational tissues by inhibiting the transcriptional activity of NF-κB. Further studies should be undertaken to define a possible implication of these natural spices in the management of preterm labour and delivery.

The TLR2 Ligand FSL‐1 and the TLR5 Ligand Flagellin Mediate Pro‐Inflammatory and Pro‐Labour Response via MyD88/TRAF6/NF‐κB‐Dependent Signalling

Toll‐like receptors (TLRs) 2 and 5 induce inflammation via the adapter proteins myeloid differentiation factor 88 (MyD88) and TNFR‐associated factor 6 (TRAF6) and the transcription factor nuclear factor‐kappa B (NF‐κB). The aims of this study were to determine the effects of the TLR5 ligand flagellin and the TLR2 ligand FSL‐1 on pro‐inflammatory and pro‐labour mediators in human fetal membranes and myometrium, and to establish whether their actions are dependent on MyD88, TRAF6 and NF‐κB.

SIRT6 Is Decreased with Preterm Labor and Regulates Key Terminal Effector Pathways of Human Labor in Fetal Membranes

ABSTRACT Preterm birth is a major determinant of neonatal mortality and morbidity, affecting approximately one-third of preterm births as a result of prelabor rupturing of membranes. Infection and inflammation have strong causal links to preterm delivery, resulting in the activation of nuclear factor-kappaB (NFKB) and its downstream targets. Human sirtuin (SIRT) 6, which has ADP-ribosyl transferase and deacetylase activity, exhibits anti-inflammatory actions. The aims of this study were to determine the effect of 1) human preterm labor on SIRT6 expression in human gestational tissue and 2) the effect in primary amnion cells of SIRT6 inhibition, using small interfering RNA (siRNA) on prolabor mediators. To determine the effect of human preterm labor on SIRT6 expression, human fetal membranes were collected from women at preterm at the time of Cesarean section (no labor; n = 9) and from women after spontaneous labor and delivery (n = 9). SIRT6 mRNA and protein expression were significantly lower in fetal membranes after spontaneous preterm labor. Transfection of primary amnion cells with SIRT6 siRNA was associated with an increase in IL-1beta-induced proinflammatory cytokine gene expression and release (IL6, IL8, TNF [TNF-alpha]), cyclooxygenase ([COX]-2; official symbol PTGS2) expression and subsequent prostaglandin (PGE2 and PGF2alpha) release, and MMP9 gene expression and release of pro-MMP9. To determine whether SIRT6 affects NFKB transcriptional activity, primary amnion cells were transfected with NFKB tagged with luciferase and stimulated with IL1B. As expected, IL1B induced NFKB transcriptional activity. However, when cells were also cotransfected with a vector expressing SIRT6, there was a decrease in NFKB transcriptional activity. In conclusion, SIRT6 plays a role in regulating the terminal effector pathways of human labor and delivery via the NFKB pathway.

Apelin Is Decreased With Human Preterm and Term Labor and Regulates Prolabor Mediators in Human Primary Amnion Cells

A critical role of proinflammatory mediators including cytokines, prostaglandins, and extracellular matrix remodeling enzymes in the processes of human labor and delivery, at term and preterm, has been demonstrated. In nongestational tissues, apelin plays an important role in a number of physiologic processes, including the regulation of inflammation. However, the role and regulation of apelin and the apelin receptor (APJ) in human gestational tissues are not known. The aims of this study were to determine the effect of (i) preterm and term labor on apelin and APJ expression in human gestational tissues and (ii) apelin small interfering RNA (siRNA) knockdown in human primary amnion cells on prolabor mediators. Human placenta and fetal membranes were collected from term nonlaboring women and women after spontaneous labor and delivery. Preterm and term spontaneous labor were associated with significantly lower apelin expression in fetal membranes. On the other hand, there was no effect of labor on APJ expression and no effect of term labor on placental apelin or APJ expression. Transfection of primary amnion cells with apelin siRNA was associated with significantly increased interleukin (IL)-1β-induced IL-6 and IL-8 release and cyclooxygenase-2 messenger RNA (mRNA) expression and resultant prostaglandin E2 and prostaglandin F2α release. There was no effect of apelin siRNA on matrix metalloproteinase (MMP)-9 mRNA expression and pro MMP-9 release. In summary, human labor downregulates apelin expression in human fetal membranes. Furthermore, a role of apelin in the regulation of proinflammatory and prolabor mediators in human fetal membranes is supported by our studies.

Omentin-1 Is Decreased in Maternal Plasma, Placenta and Adipose Tissue of Women with Pre-Existing Obesity

Objective The aim of this study was to determine (i) the effect of maternal obesity and gestational diabetes mellitus (GDM) on (i) the circulating levels of omentin-1 in cord and maternal plasma, and (ii) gene expression and release of omentin-1 from human placenta and adipose tissue. The effect of pregnancy on circulating omentin-1 levels was also determined. Design Omentin-1 levels were measured in maternal and cord plasma from obese and non-obese normal glucose tolerant women (NGT; n = 44) and women with GDM (n = 39) at the time of term elective Caesarean section. Placenta and adipose tissue expression and release of omentin-1 was measured from 22 NGT and 22 GDM women collected at the time of term elective Caesarean section. Omentin-1 levels were also measured in maternal plasma from 13 NGT women at 11 and 28 weeks gestation and 7 weeks postpartum. Results Maternal obesity was associated with significantly lower omentin-1 levels in maternal plasma; however, there was no effect of maternal obesity on cord omentin levels. Omentin-1 gene expression was lower in placenta and adipose tissue obtained from women with pre-existing obesity. In addition to this, adipose tissue release of omentin-1 was significantly lower from obese pregnant women. Omentin-1 levels were significantly lower in non-obese GDM compared to non-obese NGT women. However, there was no difference in omentin-1 levels between obese NGT and obese GDM women. There was no effect of GDM on cord omentin levels, and placental and adipose tissue omentin-1 expression. Maternal omentin-1 levels were negatively correlated with fetal birthweight and fetal ponderal index. Conclusions The data presented in this study demonstrate that pre-existing maternal obesity is associated with lower omentin-1 expression in placenta, adipose tissue and maternal plasma. Alteration in omentin-1 in pregnancy may influence the development of metabolic disorders in offspring later in life.

TREM-1 Expression Is Increased in Human Placentas From Severe Early-Onset Preeclamptic Pregnancies Where It May Be Involved in Syncytialization

Preeclampsia, a major cause of maternal and perinatal morbidity and mortality, is thought to be attributable to dysregulation of trophoblast invasion and differentiation. Microarray studies have shown that triggering receptor expressed on myeloid cells (TREM) 1, a cell surface molecule involved in the inflammatory response, is increased in preeclamptic placentas. The aim of this study was to determine the level of TREM-1 expression in severe early-onset preeclamptic placentas and its functional role in trophoblast differentiation. Placenta was obtained from women with severe early-onset preeclampsia (n = 19) and gestationally matched preterm controls placentas (n = 8). The TREM-1 expression was determined by quantitative reverse transcriptase polymerase chain reaction and Western blotting. The effect of TREM-1 small interfering RNA on cell fusion and differentiation was assessed in BeWo cells. The effect of oxygen tension on TREM-1 levels, in basal or forskolin-treated BeWo cells, was also assessed. The TREM-1 was localized to the syncytiotrophoblast layer, and TREM-1 messenger RNA and protein expression was significantly increased in preeclamptic placentas. The BeWo cells treated with forskolin were associated with increased TREM-1 expression. The TREM-1 knockdown inhibited forskolin-induced expression of the differentiation marker β-human chorionic gonadotropin but had no effect on the cell-fusion marker E-cadherin. The increase in TREM-1 expression in BeWo cells treated with forskolin during normoxic conditions was reduced in forskolin-treated cells under hypoxic conditions. In conclusion, TREM-1 is increased in preeclamptic placentas and by forskolin treatment. Knockdown of TREM-1 by RNA interference inhibits cell differentiation but has no effect on cell–cell fusion. Finally, we show that TREM-1 upregulation is attenuated under hypoxic conditions in which cell differentiation is impaired.

MAPK and AP-1 proteins are increased in term pre-labour fetal membranes overlying the cervix: Regulation of enzymes involved in the degradation of fetal membranes

Fetal membranes overlying the cervix (i.e. supracervical site, SCS) are characterised by increased extracellular matrix (ECM) degradation. In non-gestational tissues, the mitogen activated protein kinase (MAPK) and activator protein (AP)-1 family are involved in the regulation of the ECM degrading enzyme metalloproteinase (MMP)-9. The aims of this study were (i) to compare the expression of AP-1 proteins in fetal membranes from the SCS and a distal site (DS), and (ii) determine if the MAPK/AP-1 pathway is involved in the regulation of MMP-9. Fetal membranes overlying the cervix were identified in situ in women undergoing term elective Caesarean section. Immunohistochemistry (n = 6) was used to localise the expression of the MAPK proteins ERK (total and phosphorylated), JNK (total and phosphorylated) and p38 MAPK (total and phosphorylated), and the AP-1 proteins JunB, cJun (total and phosphorylated), JunD, cFos and FosD. There was no difference in JNK, p38 MAPK, FosB, cJun and JunD protein expression between SC and distal fetal membranes. However, when compared to DS, the intensity and/or extent of staining of ERK, p-ERK, p-JNK, p-p38 MAPK, cFos, JunB and p-cJun were greater in amnion and chorion obtained from the SCS. In order to elucidate a role for these proteins in ECM degradation, pharmacological inhibitors of MAPK protein activation were utilised in primary amnion cells. The ERK inhibitor U0126, JNK inhibitor SP600125 and p38 MAPK inhibitor SB202190 all significantly decreased IL-β-induced MMP-9 gene expression and pro MMP-9 in human primary amnion cells. In summary, at term, non laboured SC fetal membranes are characterised by increased expression of MAPK and AP-1 proteins. MMP-9 expression and production was significantly suppressed by inhibitors of three key enzymes in the signalling cascades leading to AP-1 formation, ERK 1/2, JNK and p38 MAPK. Thus, the MAPK/AP-1 pathway may play a role in the degradation of the ECM at the SCS making it more susceptible to membrane rupture.