Cartiotonic steroids affect monolayer permeability in lymphatic endothelial cells.

Edema is common in preeclampsia (preE), a hypertensive disorder of pregnancy. Cardiotonic steroids (CTSs) such as marinobufagenin (MBG) are involved in the pathogenesis of preE. To assess whether CTSs are involved in the leakage of lymphatic endothelial cell (LEC), we evaluated their effect on monolayer permeability of LECs (MPLEC) in culture. A rat mesenteric LECs were treated with DMSO (vehicle), and CTSs (MBG, CINO, OUB) at concentrations of 1, 10, and 100 nM. Some LECs were pretreated with 1 µM L-NAME (N-Nitro-L-Arginine Methyl Ester) before adding 100 nM MBG or cinobufotalin (CINO). Expression of ß-catenin and vascular endothelial (VE)-cadherin in CTS-treated LECs was measured by immunofluorescence and MPLEC was quantified using a fluorescence plate reader. Western blot was performed to measure ß-catenin and VE-cadherin protein levels and myosin light chain 20 (MLC20) phosphorylation. MBG (≥ 1 nM) and CINO (≥ 10 nM) caused an increase (p < 0.05) in the MPLEC compared to DMSO while ouabain (OUB) had no effect. Pretreatment of LECs with 1 µM L-NAME attenuated (p < 0.05) the MPLEC. The ß-catenin expression in LECs was downregulated (p < 0.05) by MBG and CINO. However, there was no effect on the LECs tight junctions for the CINO group. VE-cadherin expression was downregulated (p < 0.05) by CINO, and MLC20 phosphorylation was upregulated (p < 0.05) by MBG. We demonstrated that MBG and CINO caused an increase in the MPLEC, which were attenuated by L-NAME pretreatment. The data suggest that CTSs exert their effect via nitric-oxide-dependent signaling pathway and may be involved in vascular leak syndrome of LEC lining in preE.

Cinobufotalin impedes Sw.71 cytotrophoblast cell line function via cell cycle arrest and apoptotic signaling.

Preeclampsia (preE) is a hypertensive disorder of pregnancy. Cardiotonic steroids (CTS) are endogenous inhibitors of Na+/K+ ATPase, and at least one CTS, marinobufagenin (MBG), is elevated in a rat model of preE prior to the development of the syndrome. MBG and ouabain impair cytotrophoblast (CTB) cell function, which is critical for placental development. We evaluated the effect of a CTS, cinobufotalin (CINO), on CTB cell function in vitro. CINO at ≥1 nM inhibited CTB cell proliferation, migration, and invasion (p < 0.05), but had no effect on cell viability. There was a higher (p < 0.05) percentage of G0/G1 phase cells in groups treated with CINO at ≥1 nM. CINO caused an increase in stress signaling p38 MAPK and a positive annexin-V staining in CTB cells, indicating the activation of apoptotic signaling. However, the CINO-induced apoptotic signaling was prevented by p38 inhibition. These data demonstrate that CINO impairs CTB cell function via cell cycle arrest and apoptotic signaling.

Activation of the renin-angiotensin system stimulates biliary hyperplasia during cholestasis induced by extrahepatic bile duct ligation.

Cholangiocyte proliferation is regulated in a coordinated fashion by many neuroendocrine factors through autocrine and paracrine mechanisms. The renin-angiotensin system (RAS) is known to play a role in the activation of hepatic stellate cells and blocking the RAS attenuates hepatic fibrosis. We investigated the role of the RAS during extrahepatic cholestasis induced by bile duct ligation (BDL). In this study, we used normal and BDL rats that were treated with control, angiotensin II (ANG II), or losartan for 2 wk. In vitro studies were performed in a primary rat cholangiocyte cell line (NRIC). The expression of renin, angiotensin-converting enzyme, angiotensinogen, and angiotensin receptor type 1 was evaluated by immunohistochemistry (IHC), real-time PCR, and FACs and found to be increased in BDL compared with normal rat. The levels of ANG II were evaluated by ELISA and found to be increased in serum and conditioned media of cholangiocytes from BDL compared with normal rats. Treatment with ANG II increased biliary mass and proliferation in both normal and BDL rats. Losartan attenuated BDL-induced biliary proliferation. In vitro, ANG II stimulated NRIC proliferation via increased intracellular cAMP levels and activation of the PKA/ERK/CREB intracellular signaling pathway. ANG II stimulated a significant increase in Sirius red staining and IHC for fibronectin that was blocked by angiotensin receptor blockade. In vitro, ANG II stimulated the gene expression of collagen 1A1, fibronectin 1, and IL-6. These results indicate that cholangiocytes express a local RAS and that ANG II plays an important role in regulating biliary proliferation and fibrosis during extraheptic cholestasis.

Reduced urinary angiotensinogen excretion in preeclampsia.

OBJECTIVE: This study evaluated urinary angiotensinogen in preeclampsia. METHODS: Normal pregnant (n = 57) and preeclamptic patients (n = 31); Normal pregnant (n = 10) and preeclamptic rats (n = 10) were studied. Urinary angiotensinogen and plasma angiotensin II were assayed by enzyme-linked immunosorbent assay (ELISA). RESULTS: Urinary angiotensinogen in preeclampsia patients (2.0 ± 1.1 ng/mg creatinine) was suppressed (*p < 0.05) compared to normal pregnant (2.7 ± 1.5 ng/mg creatinine). Plasma angiotensin II in preeclampsia patients (preeclampsia: 36.2 ± 7; normal pregnant: 48.1 ± 5 fmol/mL) was lower. The similar result was observed in preeclampsia rat model. CONCLUSIONS: The reduced urinary excretion of angiotensinogen was both in human preeclampsia patients and rat model of preeclampsia.

Internalization of exogenous ADP-ribosylation factor 6 (Arf6) proteins into cells.

Endogenous Arf6 is a myristoylated protein mainly involved in endosomal membrane traffic and structural organization at the plasma membrane. It has been shown that Arf6 mediates cancer cell invasion and shedding of plasma membrane microvesicles derived from tumor cells. In this article, we determined that Arf6 proteins both in the GDP and GTPγS bound forms can enter cells when simply added in the cell culture medium without requiring the myristoyl group. The GTPγS bound can enter cells at a faster rate than the GDP-bound Arf6. Despite the role of the endogenous Arf6 in endocytosis and membrane trafficking, the internalization of exogenous Arf6 may involve non-endocytic processes. As protein therapeutics is becoming important in medicine, we examined the effect of the uptake of Arf6 proteins on cellular functions and determined that exogenous Arf6 inhibits proliferation, invasion, and migration of cells. Future studies of the internalization of Arf6 mutants will reveal key residues that play a role in the internalization of Arf6 and its interaction and possible structural conformations bound to the plasma membrane.

Differential Effects of In Vitro Treatment with Cinobufotalin on Three Types of Ovarian Cancer Cells.

BACKGROUND/AIM: Cinobufotalin (CINO), a cardiotonic steroid, has been used as an anticancer agent. This study assessed the cell-specific effect of CINO on SK-OV-3, CRL-1978 and CRL-11731 ovarian cancer cells which differ in terms of their respective karyotypes. MATERIALS AND METHODS: Cell cultures were treated with CINO (0.1, 1, 5 and 10 µM) for 24, 48, and 72 h. Cell proliferation, migration, and invasion were measured using CellTiter, Cytoselect, and FluoroBlock assays, respectively. Expression of proliferating cell nuclear antigen (PCNA) was evaluated by western blot analysis. Cell viability was determined by fluorescence-activated cell sorting. Immunofluorescence was performed using Annexin-V staining and fluorescein isothiocyanate (FITC). Mitochondrial membrane potential (MMP) was measured using MitoTracker™ Red. RESULTS: CINO at 0.5 µM inhibited SK-OV-3, CRL-1978, and CRL-11731 proliferation, migration, and invasion. Each cell type differed in response to CINO doses for PCNA, Annexin-V expression and MMP. CONCLUSION: The antineoplastic property of CINO is consistent, but its mode of action varies among cell lines.

Differential Mechanism of Action of 3,4',7-O-trimethylquercetin in Three Types of Ovarian Cancer Cells.

BACKGROUND/AIM: 3,4',7-O-trimethylquercetin (34'7TMQ), a derivative of quercetin, inhibited ovarian cancer cell migration and invasion without affecting proliferation. In this study, the apoptotic effect of 34'7TMQ on three cancer cell lines (CRL-1978, CRL-11731, SK-OV-3) was evaluated. MATERIALS AND METHODS: Expression of pro-apoptotic proteins such as Bax/Bcl-2 ratio, p38 MAP kinase, and caspase-9 were measured by western blot analysis. Annexin-V staining was performed to visualize apoptotic signaling. RESULTS: Caspase-9 was up-regulated in all three cell lines. Bax/Bcl-2 ratio was up-regulated in CRL-1978 and SK-OV-3 but down-regulated in CRL-11731. The p38 MAPK was down-regulated in CRL-1978, up-regulated in SK-OV-3, and had differential expression in CRL-11731. Annexin V staining indicated that 34'7TMQ at 6.25 µM induced apoptotic signaling in the CRL-1978 ovarian cancer cell line. CONCLUSION: 34'7TMQ induced apoptosis in three types of cancer cell lines but it appears to have a different mechanism of action in each cell line.

Diabetes and pre-eclampsia affecting pregnancy: a retrospective cross-sectional study.

The interaction between pre-eclampsia and diabetes mellitus (DM) is far from being completely understood. In this study, we compared normal pregnancies with those complicated with pre-eclampsia, gestational DM, and/or pre-existing diabetes to assess the effects of hyperglycemia on placental development. AnInstitutional Review Board (IRB) approved retrospective cross-sectional study with 621 subjects was performed. Statistical analysis was performed using Duncan's post hoc test and analysis of variance. Regardless of diabetes status, patients with pre-eclampsia delivered prematurely. Patients in the group with pre-eclampsia and pregestational diabetes delivered much earlier, at 35.0±0.4 weeks, when compared with the patients that had pre-eclampsia with gestational diabetes and pre-eclampsia with no diabetes (*P<0.05 for each). Additionally, patients with pre-existing diabetes who developed pre-eclampsia delivered smaller babies than those with pre-existing diabetes without pre-eclampsia (1.00±0.03, P<0.05 for each). Pre-existing diabetes with added insult of pre-eclampsia led to fetal growth restriction. This outcome validates the understanding that elevated glucose earlier in pregnancy alters placentogenesis and leads to fetal growth restriction.

Structure-Activity Relationships of Methylquercetin on Anti-migration and Anti-proliferation Activity in B16 Melanoma Cells.

BACKGROUND: Melanoma is a malignant skin tumor and quercetin has been reported to inhibit metastasis. A quercetin glycoside and 7 methylquercetins were synthesized from rutin to investigate structure-activity relationships. MATERIALS AND METHODS: We evaluated the anti-proliferative and anti-migration activity of quercetin glycoside and 7 methylquercetins in murine B16 melanoma cells by commercially available kits. We also examined the effect of these compounds on growth of human fibroblast cells to evaluate cytotoxicity. RESULTS: 3-O-methylquercetin (2) exhibited 30, 38, 45% migration activity at 25, 12.5, 6.25 µM respectively. Furthermore, 3,4',7-O-trimethylquercetin (5) and 3,4'-O-dimethylquercetin (3) inhibited migration more potent than 2 with no cytotoxicity. 3-hydroxymethylquercetin and quercetin glycoside exhibited no anti-migration activity. Furthermore, the 3 and 4 inhibited melanoma proliferation with no cytotoxicity. CONCLUSION: The methoxyl group at the C-3 position plays an important role in inhibiting the migration of B16 melanoma cells.

3,4',7-O-trimethylquercetin Inhibits Invasion and Migration of Ovarian Cancer Cells.

BACKGROUND/AIM: Methylquercetin, 3,4',7-O-trimethylquercetin (34'7TMQ), has been reported to inhibit metastasis. Recently, we demonstrated that 34'7TMQ inhibited the in vitro melanoma B16 cell metastatic activity. We evaluated the effect of 34'7TMQ on three ovarian cancer cells (SK-OV-3, CRL11731 and CRL1978). MATERIALS AND METHODS: Proliferation, migration and invasion were measured in 34'7TMQ-treated ovarian cancer cells by commercially available kits. We also evaluated the expression of proliferating cell nuclear antigen (PCNA), urokinase plasminogen activator (uPA), plasminogen activator inhibitor 1 (PAI-1) and matrix metalloproteinase (MMP)-2 by western blot analysis. RESULTS: 34'7TMQ inhibited ovarian cancer cell migration and invasion without effecting proliferation. Furthermore, 34'7TMQ inhibited the expression of uPA and MMP-2; however, it had no effect on PAI-1 and PCNA. CONCLUSION: 34'7TMQ significantly regulates the expressions of protein to inhibit metastasis in ovarian cancers, while the regulatory effects of 34'7TMQ vary between different ovarian cancer cell lines.

Synthetic Receptors Induce Anti Angiogenic and Stress Signaling on Human First Trimester Cytotrophoblast Cells.

The cytotrophoblast (CTB) cells of the human placenta have membrane receptors that bind certain cardiotonic steroids (CTS) found in blood plasma. One of these, marinobufagenin, is a key factor in the etiology of preeclampsia. Herein, we used synthetic receptors (SR) to study their effectiveness on the angiogenic profile of human first trimester CTB cells. The humanextravillous CTB cells (Sw.71) used in this study were derived from first trimester chorionic villus tissue. Culture media of CTB cells treated with ≥1 nM SR level revealed sFlt-1 (Soluble fms-like tyrosine kinase-1) was significantly increased while VEGF (vascular endothelial growth factor) was significantly decreased in the culture media (* p < 0.05 for each) The AT2 receptor (Angiotensin II receptor type 2) expression was significantly upregulated in ≥1 nM SR-treated CTB cells as compared to basal; however, the AT1 (Angiotensin II receptor, type 1) and VEGFR-1 (vascular endothelial growth factor receptor 1) receptor expression was significantly downregulated (* p < 0.05 for each). Our results show that the anti-proliferative and anti-angiogenic effects of SR on CTB cells are similar to the effects of CTS. The observed anti angiogenic activity of SR on CTB cells demonstrates that the functionalized-urea/thiourea molecules may be useful as potent inhibitors to prevent CTS-induced impairment of CTB cells.

Attenuation of hyperglycemia-induced apoptotic signaling and anti-angiogenic milieu in cultured cytotrophoblast cells.

OBJECTIVE: Preeclampsia (preE) is a hypertensive disorder that occurs 20% in diabetic pregnancy. We have shown that hyperglycemia impairs cytotrophoblast cell (CTB) function. In this study, we assess apoptotic and anti-angiogenic signaling in excess glucose-induced CTBs. STUDY DESIGN: Human extravillous CTBs (Sw. 71) were treated with 100, 150, 200, 300, or 400 mg/dL glucose for 48 h. Some cells were pretreated with a p38 inhibitor (SB203580) or a peroxisome proliferator-activated receptor gamma (PPARγ) ligand (rosiglitazone) or with D-mannitol. Cell lysates were utilized to measure p38 MAPK phosphorylation, PPARγ, Bcl-2-associated-X protein (Bax), anti-apoptotic Bcl-2, caspase-9, and cyclooxygenase-2 (Cox-2) expression by western blot. Levels of the vascular endothelial growth factor (VEGF), placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), soluble endoglin (sEng), and interleukin 6 (IL-6) were measured in culture media using ELISA kits. Statistical comparisons were performed using analysis of variance with Duncan's post hoc test. RESULTS: p38 phosphorylation and PPARγ were upregulated (p < 0.05) in CTBs treated with ≥150 mg/dL glucose compared to basal (100 mg/dL). Expressions of Bax/Bcl-2, Cox-2, and caspase-9 were upregulated (p < 0.05) in CTBs treated with ≥150 mg/dL glucose. Secretion of sFlt-1, sEng, and IL-6 was increased while VEGF and PIGF were decreased in CTB-treated ≥150 mg/dl of glucose (*p < 0.01 for each). SB203580 or rosiglitazone pretreatment significantly attenuated hyperglycemia-induced apoptotic and anti-angiogenic signaling. D-Mannitol had no effect. CONCLUSION: Hyperglycemia induced apoptotic and anti-angiogenic signaling in CTBs. The observed diminution of hyperglycemia-induced signaling by SB203580 or rosiglitazone pretreatment suggests the involvement of apoptotic and anti-angiogenic signaling in CTB dysfunction.

Apoptotic and stress signaling markers are augmented in preeclamptic placenta and umbilical cord.

OBJECTIVE: Preeclampsia (preE) has a significant link to alterations of placental function leading to stress and apoptotic signaling, which pass the placental barrier and leave persistent defect in the circulation of the offspring. We assessed apoptotic signaling in placentas and umbilical cords from patients with and without preE. METHODS: We collected placental and cord tissues from 27 normal pregnant (NP) women and 20 preE consenting patients after delivery in an IRB approved prospective study. p38 mitogen-activated protein kinase (p38 MAPK) phosphorylation, pro-apoptotic Bcl-2-associated X (Bax), anti-apoptotic Bcl-2, caspase-9, and pro-inflammatory cyclooxygenase-2 (Cox-2) were evaluated by western blot and immunohistochemistry. Comparisons were performed using Student's t-test. RESULTS: p38 phosphorylation (Placenta: 1.5 fold, Cord: 1.7 fold), ratio of Bax/Bcl-2 (Placenta: 1.7 fold, Cord: 2.2 fold), caspase-9 (Placenta: 1.5 fold, Cord: 1.8 fold) and Cox-2 (Placenta: 2.5 fold, Cord: 2.3 fold) were up-regulated (p < 0.05) in preE compared to NP patients. Average hospital stays for preE babies were longer than NP babies. No complications were reported for NP babies; however, all of preE babies had multiple complications. CONCLUSIONS: Apoptotic and stress signaling are augmented in preE placenta and cord tissue that alter the intrauterine environment and activates the detrimental signaling that is transported to fetus.

A p38 mitogen-activated protein kinase inhibitor attenuates cardiotonic steroids-induced apoptotic and stress signaling in a Sw-71 cytotrophoblast cell line.

INTRODUCTION: Preeclampsia (preE) is characterized by abnormal placentation. Marinobufagenin (MBG), a cardiotonic steroid (CTS), inhibits the function of cytotrophoblast cells (CTBs). We demonstrated that CTSs induce anti-angiogenic and anti-proliferative effects in Sw-71 CTBs. This study tests that CTSs induce apoptotic and stress signaling. METHODS: Human extravillous Sw-71 CTBs were incubated with 0, 0.1, 1, 10, and 100 nM of each of three CTSs (MBG, cinobufatalin (CINO) and ouabain (OUB)) for 48 h. Some cells were pretreated with 10 µM p38 mitogen-activated protein kinase (p38 MAPK) inhibitor (SB203580) for 2 h prior to CTSs treatment. We analyzed p38 MAPK phosphorylation, expression of pro-inflammatory protein cyclooxygenase-2 (Cox-2) and ratio of pro-apoptotic Bcl-2-associated X protein (Bax) to anti-apoptotic Bcl-2 protein by western blot in CTSs-treated CTBs lysates. Levels of vascular endothelial growth factor (VEGF), placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1) and soluble endoglin (sEng) were measured in culture media using ELISA kits. Statistical comparisons were performed using analysis of variance with Duncan's post hoc test. RESULTS: p38 MAPK phosphorylation, expression of Cox-2 and Bax/Bcl-2 was upregulated (*p < 0.05) in CTBs exposed to ≥ 0.1 nM CTSs. Secretion of sFlt-1 and sEng were increased while VEGF and PIGF were decreased in Sw-71 CTBs treated ≥1 nM of each CTSs (*p < 0.01 for each). The SB203580 pretreatment of CTBs significantly attenuated CTS-induced effects. DISCUSSION: Exposure of Sw-71 CTBs to CTSs induced apoptotic and stress signaling and causing anti-angiongenic effect. The observed diminution of CTS-induced signaling by SB203580 pretreatment implicates p38 MAPK as a regulator of these pathways.

Mechanosensing and Regulation of Cardiac Function.

The role of mechanical force as an important regulator of structure and function of mammalian cells, tissues, and organs has recently been recognized. However, mechanical overload is a pathogenesis or comorbidity existing in a variety of heart diseases, such as hypertension, aortic regurgitation and myocardial infarction. Physical stimuli sensed by cells are transmitted through intracellular signal transduction pathways resulting in altered physiological responses or pathological conditions. Emerging evidence from experimental studies indicate that ß1-integrin and the angiotensin II type I (AT1) receptor play critical roles as mechanosensors in the regulation of heart contraction, growth and leading to heart failure. Integrin link the extracellular matrix and the intracellular cytoskeleton to initiate the mechanical signalling, whereas, the AT1 receptor could be activated by mechanical stress through an angiotensin-II-independent mechanism. Recent studies show that both Integrin and AT1 receptor and their downstream signalling factors including MAPKs, AKT, FAK, ILK and GTPase regulate heart function in cardiac myocytes. In this review we describe the role of mechanical sensors residing within the plasma membrane, mechanical sensor induced downstream signalling factors and its potential roles in cardiac contraction and growth.