Metformin improves relevant disease parameters in an autosomal dominant polycystic kidney disease mouse model.

Autosomal dominant polycystic kidney disease (ADPKD), caused by mutations in the polycystin 1 (PKD1) or polycystin 2 genes, presents with progressive development of kidney cysts and eventual end-stage kidney disease with limited treatment options. Previous work has shown that metformin reduces cyst growth in rapid ADPKD mouse models via inhibition of cystic fibrosis transmembrane conductance regulator-mediated fluid secretion, mammalian target of rapamycin, and cAMP pathways. The present study importantly tested the effectiveness of metformin as a therapy for ADPKD in a more clinically relevant Pkd1RC/RC mouse model, homozygous for the R3277C knockin point mutation in the Pkd1 gene. This mutation causes ADPKD in humans. Pkd1RC/RC male and female mice, which have a slow progression to end-stage kidney disease, received metformin (300 mg/kg/day in drinking water vs. water alone) from 3 to 9 or 12 mo of age. As previously reported, Pkd1RC/RC females had a more severe disease phenotype as compared with males. Metformin treatment reduced the ratio of total kidney weight-to-body weight relative to age-matched and sex-matched untreated controls at both 9 and 12 mo and reduced the cystic index in females at 9 mo. Metformin also increased glomerular filtration rate, lowered systolic blood pressure, improved anemia, and lowered blood urea nitrogen levels relative to controls in both sexes. Moreover, metformin reduced gene expression of key inflammatory markers and both gene and protein expression of kidney injury marker-1 and cyclin-dependent kinase-1 versus untreated controls. Altogether, these findings suggest several beneficial effects of metformin in this highly relevant slowly progressive ADPKD mouse model, which may help inform new ADPKD therapies in patients.NEW & NOTEWORTHY Metformin treatment improved ADPKD disease severity in a relevant, slowly progressive ADPKD mouse model that recapitulates a PKD-associated PKD1 mutation. Relative to controls, metformin reduced kidney weight/body weight, cystic index and BUN levels, while improving GFR, blood pressure and anemia. Metformin also reduced key inflammatory and injury markers, along with cell proliferation markers. These findings suggest several beneficial effects of metformin in this ADPKD mouse model, which may help inform new ADPKD therapies in patients.

ß1Pix exchange factor stabilizes the ubiquitin ligase Nedd4-2 and plays a critical role in ENaC regulation by AMPK in kidney epithelial cells.

Our previous work has established that the metabolic sensor AMP-activated protein kinase (AMPK) inhibits the epithelial Na+ channel (ENaC) by promoting its binding to neural precursor cell-expressed, developmentally down-regulated 4-2, E3 ubiquitin protein ligase (Nedd4-2). Here, using MS analysis and in vitro phosphorylation, we show that AMPK phosphorylates Nedd4-2 at the Ser-444 (Xenopus Nedd4-2) site critical for Nedd4-2 stability. We further demonstrate that the Pak-interacting exchange factor ß1Pix is required for AMPK-mediated inhibition of ENaC-dependent currents in both CHO and murine kidney cortical collecting duct (CCD) cells. Short hairpin RNA-mediated knockdown of ß1Pix expression in CCD cells attenuated the inhibitory effect of AMPK activators on ENaC currents. Moreover, overexpression of a ß1Pix dimerization-deficient mutant unable to bind 14-3-3 proteins (Δ602-611) increased ENaC currents in CCD cells, whereas overexpression of WT ß1Pix had the opposite effect. Using additional immunoblotting and co-immunoprecipitation experiments, we found that treatment with AMPK activators promoted the binding of ß1Pix to 14-3-3 proteins in CCD cells. However, the association between Nedd4-2 and 14-3-3 proteins was not consistently affected by AMPK activation, ß1Pix knockdown, or overexpression of WT ß1Pix or the ß1Pix-Δ602-611 mutant. Moreover, we found that ß1Pix is important for phosphorylation of the aforementioned Nedd4-2 site critical for its stability. Overall, these findings elucidate novel molecular mechanisms by which AMPK regulates ENaC. Specifically, they indicate that AMPK promotes the assembly of ß1Pix, 14-3-3 proteins, and Nedd4-2 into a complex that inhibits ENaC by enhancing Nedd4-2 binding to ENaC and its degradation.

AMPK phosphorylation of the ß1Pix exchange factor regulates the assembly and function of an ENaC inhibitory complex in kidney epithelial cells.

The metabolic sensor AMP-activated protein kinase (AMPK) inhibits the epithelial Na+ channel (ENaC), a key regulator of salt reabsorption by the kidney and thus total body volume and blood pressure. Recent studies have suggested that AMPK promotes the association of p21-activated kinase-interacting exchange factor-ß1 ß1Pix, 14-3-3 proteins, and the ubiquitin ligase neural precursor cell expressed developmentally downregulated protein (Nedd)4-2 into a complex that inhibits ENaC by enhancing Nedd4-2 binding to ENaC and ENaC degradation. Functional ß1Pix is required for ENaC inhibition by AMPK and promotes Nedd4-2 phosphorylation and stability in mouse kidney cortical collecting duct cells. Here, we report that AMPK directly phosphorylates ß1Pix in vitro. Among several AMPK phosphorylation sites on ß1Pix detected by mass spectrometry, Ser71 was validated as functionally significant. Compared with wild-type ß1Pix, overexpression of a phosphorylation-deficient ß1Pix-S71A mutant attenuated ENaC inhibition and the AMPK-activated interaction of both ß1Pix and Nedd4-2 to 14-3-3 proteins in cortical collecting duct cells. Similarly, overexpression of a ß1Pix-Δ602-611 deletion tract mutant unable to bind 14-3-3 proteins decreased the interaction between Nedd4-2 and 14-3-3 proteins, suggesting that 14-3-3 binding to ß1Pix is critical for the formation of a ß1Pix/Nedd4-2/14-3-3 complex. With expression of a general peptide inhibitor of 14-3-3-target protein interactions (R18), binding of both ß1Pix and Nedd4-2 to 14-3-3 proteins was reduced, and AMPK-dependent ENaC inhibition was also attenuated. Altogether, our results demonstrate the importance of AMPK-mediated phosphorylation of ß1Pix at Ser71, which promotes 14-3-3 interactions with ß1Pix and Nedd4-2 to form a tripartite ENaC inhibitory complex, in the mechanism of ENaC regulation by AMPK.

Aurora kinase A activates the vacuolar H+-ATPase (V-ATPase) in kidney carcinoma cells.

Extracellular proton-secreting transport systems that contribute to extracellular pH include the vacuolar H(+)-ATPase (V-ATPase). This pump, which mediates ATP-driven transport of H(+) across membranes, is involved in metastasis. We previously showed (Alzamora R, Thali RF, Gong F, Smolak C, Li H, Baty CJ, Bertrand CA, Auchli Y, Brunisholz RA, Neumann D, Hallows KR, Pastor-Soler NM. J Biol Chem 285: 24676-24685, 2010) that V-ATPase A subunit phosphorylation at Ser-175 is important for PKA-induced V-ATPase activity at the membrane of kidney intercalated cells. However, Ser-175 is also located within a larger phosphorylation consensus sequence for Aurora kinases, which are known to phosphorylate proteins that contribute to the pathogenesis of metastatic carcinomas. We thus hypothesized that Aurora kinase A (AURKA), overexpressed in aggressive carcinomas, regulates the V-ATPase in human kidney carcinoma cells (Caki-2) via Ser-175 phosphorylation. We found that AURKA is abnormally expressed in Caki-2 cells, where it binds the V-ATPase A subunit in an AURKA phosphorylation-dependent manner. Treatment with the AURKA activator anacardic acid increased V-ATPase expression and activity at the plasma membrane of Caki-2 cells. In addition, AURKA phosphorylates the V-ATPase A subunit at Ser-175 in vitro and in Caki-2 cells. Immunolabeling revealed that anacardic acid induced marked membrane accumulation of the V-ATPase A subunit in transfected Caki-2 cells. However, anacardic acid failed to induce membrane accumulation of a phosphorylation-deficient Ser-175-to-Ala (S175A) A subunit mutant. Finally, S175A-expressing cells had decreased migration in a wound-healing assay compared with cells expressing wild-type or a phospho-mimetic Ser-175-to-Asp (S175D) mutant A subunit. We conclude that AURKA activates the V-ATPase in kidney carcinoma cells via phosphorylation of Ser-175 in the V-ATPase A subunit. This regulation contributes to kidney carcinoma V-ATPase-mediated extracellular acidification and cell migration.

Neonatal glucocorticoid treatment increased depression-like behaviour in adult rats.

Synthetic glucocorticoid dexamethasone (DEX) is frequently used as a therapeutic agent to lessen the morbidity of chronic lung disease in premature infants. Previous studies suggested that neonatal DEX treatment altered brain development and cognitive function. It has been recognized that the amygdala is involved in emotional processes and also a critical site of neuronal plasticity for fear conditioning. Little is known about the possible long-term adverse effect of neonatal DEX treatment on amygdala function. The present study was aimed to evaluate the possible effect of neonatal DEX treatment on the synaptic function of amygdala in adult rats. Newborn Wistar rats were subjected to subcutaneous tapering-dose injections of DEX (0.5, 0.3 and 0.1 mg/kg) from post-natal day one to three, PN1-PN3. Animals were then subjected to a forced swimming test (FST) and electrophysiological recording aged eight weeks. The results of the FST showed neonatal DEX treatment increased depression-like behaviour in adulthood. After acute stress evoking, the percentage of time spent free floating is significantly increased in the DEX treated group compared with the control animals. Furthermore, neonatal DEX treatment elevated long-term potentiation (LTP) response and the phosphorylation level of MAPK in the lateral nucleus of amygdala (LA). Intracerebroventricular infusion of the MAPK inhibitor, PD98059, showed significant rescue effects including reduced depression-like behaviour and restoration of LTP to within normal range. In conclusion, our results suggested that MAPK signalling cascade in the LA plays an important role in the adverse effect of neonatal DEX treatment on amygdala function, which may result in adverse consequences in adult age, such as the enhancement of susceptibility for a depressive disorder in later life.

Oral delivery of nanomedicine for genetic kidney disease.

Chronic and genetic kidney diseases such as autosomal dominant polycystic kidney disease (ADPKD) have few therapeutic options, and clinical trials testing small molecule drugs have been unfavorable due to low kidney bioavailability and adverse side effects. Although nanoparticles can be designed to deliver drugs directly to the diseased site, there are no kidney-targeted nanomedicines clinically available, and most FDA-approved nanoparticles are administered intravenously which is not ideal for chronic diseases. To meet these challenges of chronic diseases, we developed a biomaterials-based strategy using chitosan particles (CP) for oral delivery of therapeutic, kidney-targeting peptide amphiphile micelles (KMs). We hypothesized that encapsuling KMs into CP would enhance the bioavailability of KMs upon oral administration given the high stability of chitosan in acidic conditions and mucoadhesive properties enabling absorption within the intestines. To test this, we evaluated the mechanism of KM access to the kidneys via intravital imaging and investigated the KM biodistribution in a porcine model. Next, we loaded KMs carrying the ADPKD drug metformin into CP (KM-CP-met) and measured in vitro therapeutic effect. Upon oral administration in vivo, KM-CP-met showed significantly greater bioavailability and accumulation in the kidneys as compared to KM only or free drug. As such, KM-CP-met treatment in ADPKD mice (Pkd1fl/fl;Pax8-rtTA;Tet-O-Cre which develops the disease over 120 days and mimics the slow development of ADPKD) showed enhanced therapeutic efficacy without affecting safety despite repeated treatment. Herein, we demonstrate the potential of KM-CP as a nanomedicine strategy for oral delivery for the long-term treatment of chronic kidney diseases.

Chlorella pyrenoidosa ameliorated L-NAME-induced hypertension and cardiorenal remodeling in rats.

PURPOSE: Hypertension is one of the main factors causing cardiovascular diseases. The aim of the study is to investigate the effects of Chlorella pyrenoidosa on blood pressure and cardiorenal remodeling in rats with N (ω)-nitro-L-arginine methyl ester hydrochloride (L-NAME)-induced endothelial dysfunction. METHODS: Rats were fed a diet containing L-NAME (40 mg/kg) with or without chlorella (4 or 8 %) for 5 weeks. We found that chlorella retarded the development of hypertension and cardiorenal remodeling during the 5-week experimental period. RESULTS: Although there was no difference in NO( x ) levels or plasma arginine concentrations, plasma and tissues ACE activities were significantly lower in the chlorella groups than in the L-NAME group. Moreover, tissue tumor necrosis factor-α concentrations and renal CYP4A expression were also lower in the chlorella group. CONCLUSION: These results suggest that chlorella might ameliorate the elevation of blood pressure and show cardiorenal-protective effects in nitric oxide-deficient rats, and one possible mechanism might be mediated by its ACE inhibitory activity.

Folic acid inhibits endothelial cell proliferation through activating the cSrc/ERK 2/NF-κB/p53 pathway mediated by folic acid receptor.

Folate is important for normal cell division. Folate deficiency has been implicated in various diseases, including atherosclerosis, neural tube defects, and cancer. However, the effect of folate on angiogenesis was unclear. The aim of this study was to investigate the anti-angiogenic action of folic acid (FA). FA (0-10 µmol/L) concentration-dependently decreased DNA synthesis and proliferation in cultured human umbilical venous endothelial cells (HUVEC). Western blot analyses demonstrated that the levels of p21, p27 and p53 protein in HUVEC were increased by FA. The FA-inhibited [3H]thymidine incorporation was completely blocked when the expressions of p21 and p27 were knocked-down together. Knock-down of p53 prevented the FA-induced increases in p21 and p27 protein level. The levels of phosphorylated Src (p-Src) and p-Src-FA receptor (FR) complex in HUVEC were increased by FA. Knock-down of FR reduced the FA-induced increases of p-Src and p53. The FA-induced increases of p21, p27 and p53 protein levels were abolished when cSrc was knocked-down. FA also increased NF-κB nuclear translocation and binding onto the p53 promoter. The FA-induced up-regulation of the p53 promoter activity was prevented by knocked-down of ERK. Matrigel angiogenesis assay in mice demonstrate the anti-angiogenic effect of FA in vivo. In conclusion, our data indicate that FA bound to FR in HUVEC, subsequently activated the cSrc/ERK 2/NF-κB/p53 signaling pathway, which in turn up-regulated the expression of p21 and p27, and finally resulted in cell cycle arrest at the G0/G1 phase. In the present study, we uncover a completely novel role of FA for anti-angiogenesis.

BPR0C261 is a novel orally active antitumor agent with antimitotic and anti-angiogenic activities.

BPR0C261 is a synthetic small molecule compound cytotoxic against human cancer cells and active prolonging the lifespan of leukemia mice. In the present study, we further investigated the mechanisms of its anticancer action and found that BPR0C261 inhibited microtubule polymerization through interacting with the colchicine binding sites on tubulins, disrupted microtubule arrangement and caused cell cycle arrest at G(2)/M phase in cancer cells. BPR0C261 also inhibited the clonogenic growths of cancer cells and showed cytotoxicity against human cervical cancer cells of multidrug-resistant phenotype. In addition, BPR0C261 concentration-dependently inhibited the proliferation and migration of HUVECs and disrupted the endothelial capillary-like tube formations in HUVEC and rat aorta ring cultures. Given orally, BPR0C261 inhibited angiogenesis in s.c. implanted Matrigel plugs in mice. Notably, its IC(50) values against the endothelial cell growths were approximately 10-fold lower than those against the cancer cells. It was found orally absorbable in mice and showed a good oral bioavailability (43%) in dogs. BPR0C261 permeated through the human intestinal Caco-2 cell monolayer, suggesting oral availability in humans. Orally absorbed BPR0C261 distributed readily into the s.c. xenografted tumors in nude mice in which the tumor tissue levels of BPR0C261 were found oral dose-dependent. BPR0C261 showed in vivo activities against human colorectal, gastric, and nasopharyngeal tumors in nude mice. Most interestingly, the combination of BPR0C261 plus cisplatin synergistically prolonged the lifespans of mice inoculated with murine leukemia cells. Thus, BPR0C261 is a novel orally active tubulin-binding antitumor agent with antimitotic, apoptosis-inducing, and vasculature disrupting activities.

Oral delivery of metformin by chitosan nanoparticles for polycystic kidney disease.

Nanoparticle drug delivery has many advantages over small molecule therapeutics, including reducing off-target side effects and increasing drug potency. However, many nanoparticles are administered parenterally, which is challenging for chronic diseases such as polycystic kidney disease (PKD), the most common hereditary disease worldwide in which patients need continuous treatment over decades. To address this clinical need, we present the development of nanoparticles synthesized from chitosan, a widely available polymer chosen for its ability to improve oral bioavailability. Specifically, we optimized the synthesis parameters of chitosan nanoparticles and demonstrate mucoadhesion and permeation across an intestinal barrier model in vitro. Furthermore, when administered orally to mice, ex vivo imaging of rhodamine-loaded chitosan nanoparticles showed significantly higher accumulation in the intestines compared to the free model drug, as well as 1.3 times higher serum area under the curve (AUC), demonstrating controlled release and improved serum delivery over 24 h. To test its utility for chronic diseases such as PKD, we loaded the candidate PKD drug, metformin, into chitosan nanoparticles, and upon oral administration to a PKD murine model (Pkd1fl/fl;Pax8-rtTA;Tet-O cre), a lower cyst burden was observed compared to free metformin, and was well tolerated upon repeated dosages. Blood urea nitrogen (BUN) and creatinine levels were similar to untreated mice, demonstrating kidney and biocompatibility health. Our study builds upon previous chitosan-based drug delivery approaches, and demonstrates a novel, oral nanoformulation for PKD.

Expression of Genes Encoding Manganese Peroxidase and Laccase of Ganoderma boninense in Response to Nitrogen Sources, Hydrogen Peroxide and Phytohormones.

Ganoderma produces lignolytic enzymes that can degrade the lignin component of plant cell walls, causing basal stem rot to oil palms. Nitrogen sources may affect plant tolerance to root pathogens while hydrogen peroxide (H2O2), salicylic acid (SA) and jasmonic acid (JA) play important roles in plant defense against pathogens. In this study, we examined the expression of genes encoding manganese peroxidase (MnP) and laccase (Lac) in Ganoderma boninense treated with different nitrogen sources (ammonium nitrate, ammonium sulphate, sodium nitrate and potassium nitrate), JA, SA and H2O2. Transcripts encoding MnP and Lac were cloned from G. boninense. Of the three GbMnP genes, GbMnP_U6011 was up-regulated by all nitrogen sources examined and H2O2 but was down-regulated by JA. The expression of GbMnP_U87 was only up-regulated by JA while GbMnP_35959 was up-regulated by ammonium nitrate but suppressed by sodium nitrate and down-regulated by H2O2. Among the three GbLac genes examined, GbLac_U90667 was up-regulated by ammonium nitrate, JA, SA and H2O2; GbLac_U36023 was up-regulated by JA and H2O2 while GbLac_U30636 was up-regulated by SA but suppressed by ammonium sulphate, sodium nitrate, JA and H2O2. Differential expression of these genes may be required by their different functional roles in G. boninense.

Involvement of the JNK activation in terbinafine-induced p21 up-regulation and DNA synthesis inhibition in human vascular endothelial cells.

Previously, we demonstrated that the extracellular signal-regulated kinase (ERK)-mediated pathway contributes to the terbinafine (TB)-induced increases of p21 and p53 protein level as well as decrease of DNA synthesis in human umbilical venous endothelial cells (HUVEC). The aim of this study is to examine the involvement of c-Jun NH2-terminal kinase (JNK) in the TB-induced increase of p21 protein level and DNA synthesis inhibition. Western blot analysis and kinase assay demonstrated that TB treatment increased both the protein level and the kinase activity of JNK1/2 in HUVEC. Transfection of HUVEC with JNK1 dominant negative (DN-JNK1) prevented the TB-induced increases of p21 and p53 protein level and decrease of DNA synthesis, suggesting that JNK1/2 activation is involved in the TB-induced cell cycle arrest in HUVEC. Moreover, over-expression of mitogen-activated protein kinase (MEK)-1 prevented the TB-induced increase of JNK1/2 protein levels, suggesting that MEK-1 is an upstream inhibitor of JNK. Transfection of HUVEC with DN-JNK1 prevented the TB-induced inhibition of ERK phosphorylation, suggesting that JNK1/2 might serve as a negative regulator of ERK. Taken together, our results suggest that JNK activation is involved in the TB-induced inhibition of ERK phosphorylation, p53 and p21 up-regulation and DNA synthesis inhibition in HUVEC.

Enhanced oral bioavailability of paclitaxel by D-alpha-tocopheryl polyethylene glycol 400 succinate in mice.

Paclitaxel is widely used to treat several types of solid tumors. The commercially available paclitaxel formulation contains Cremophor/ethanol as solubilizers. This study evaluated the effects of D-alpha-tocopheryl polyethylene glycol 400 succinate (TPGS 400) on the oral absorption of paclitaxel in mice. Mice were given an intravenous (18mg/kg) or oral (100mg/kg) dose of paclitaxel solubilized in Cremophor/ethanol or in TPGS 400/ethanol formulations. Paclitaxel plasma concentrations and pharmacokinetic parameters were determined. The maximal plasma concentrations of paclitaxel after an oral dose were 1.77+/-0.17 and 3.39+/-0.49microg/ml for Cremophor/ethanol and TPGS 400/ethanol formulations, respectively, with a similar time at 40-47min to reach the maximal plasma concentrations. The oral bioavailability of paclitaxel in TPGS 400/ethanol (7.8%) was 3-fold higher than that in Cremophor/ethanol (2.5%). On the other hand, the plasma pharmacokinetic profiles of intravenous paclitaxel demonstrated a superimposition for the two formulations. Furthermore, TPGS 400 concentration-dependently increased the intracellular retention of Rhodamine 123 in Caco-2 cells and enhanced paclitaxel permeability in monolayer Caco-2 cultures. TPGS 400 at concentrations up to 1mM did not inhibit testosterone 6beta-hydroxylase, a cytochrome P450 isozyme 3A in liver microsomes metabolizing paclitaxel. Our results indicated that TPGS 400 enhances the oral bioavailability of paclitaxel in mice and the enhancement may result from an increase in intestinal absorption of paclitaxel.

Terbinafine inhibits endothelial cell migration through suppression of the Rho-mediated pathway.

We showed previously that terbinafine, an allylamine with fungicidal activity, could inhibit angiogenesis by suppressing the endothelial cell proliferation. In the present study, we further showed that terbinafine (0-120 micromol/L) dose dependently inhibited the adhesion and migration of human umbilical vascular endothelial cells (HUVEC). Western blot analysis showed that terbinafine decreased the levels of Ras protein and membrane-bound RhoA protein. Moreover, the terbinafine-induced migration inhibition in HUVEC was prevented by pretreatment with farnesol or geranylgeraniol. Pretreatment of HUVEC with Ras inhibitor peptide or a ROCK (a kinase associated with RhoA for transducing RhoA signaling) inhibitor, Y27632, abolished the farnesol- or geranylgeraniol-induced prevention effect on the terbinafine-induced migration inhibition, respectively. These data suggest that the consuming or depletion of geranylgeranyl pyrophosphate and consequent suppression of protein geranylgeranylation and farnesylation, which is essential for activation of Rho GTPases and Ras, respectively, might account for the terbinafine-induced inhibition of HUVEC migration. The levels of phosphorylated focal adhesion kinase and paxillin protein and the mRNA levels of matrix metalloproteinase-2 and matrix metalloproteinase-9 were also decreased by terbinafine treatment. Taken together, these results indicate that suppression of Rho-mediated pathway might be involved in the signal transduction leading to the inhibition of cell migration caused by terbinafine in HUVEC.

Antiproliferative and antiangiogenic effects of 3-methylcholanthrene, an aryl-hydrocarbon receptor agonist, in human umbilical vascular endothelial cells.

There is increasing interest in the effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and polycyclic aromatic hydrocarbons on cardiovascular diseases. Their chemical structures are similar, although polycyclic aromatic hydrocarbons contain no chlorine as does TCDD. The biochemical mechanism of their action is mainly mediated by the aryl hydrocarbon receptor. In addition, oxidative stress also plays a role in the biological and toxic effects of these chemicals. In this study, we used an aryl hydrocarbon receptor agonist, 3-methylcholanthrene (3-MC), to investigate its effect on the proliferation and angiogenesis of human umbilical vascular endothelial cells. 3-MC suppressed DNA synthesis of human umbilical vascular endothelial cells as determined by [(3)H]thymidine incorporation in a concentration-dependent fashion and arrested cells at the G0/G1 phase of the cell cycle. Interestingly, the inhibition of DNA synthesis by 3-MC was eliminated to a greater extent by aryl hydrocarbon receptor antagonists, alpha-NF (0.5 and 1 microM) and resveratrol (5 and 10 microM), than by the antioxidant, N-acetylcysteine (5 and 10 mM). Cell permeability, adhesion, and tube formation in human umbilical vascular endothelial cells exposed to 3-MC decreased in concentration-dependent manners. We also demonstrated that cell adhesion signaling (phosphorylated focal adhesion kinase (FAK)) decreased upon 3-MC treatment, suggesting that cell adhesion inhibited by 3-MC might be due to inhibition of cell adhesion signaling. Additionally, alpha-naphthoflavon (alpha-NF) ameliorated the effects of 3-MC on cell permeability, adhesion and tube formation, indicating the involvement of the aryl hydrocarbon receptor in angiogenesis. The results suggest that the adverse effects of 3-MC are mainly mediated by the aryl hydrocarbon receptor and not via increased oxidative stress.

Synergistic Blockade of EGFR and HER2 by New-Generation EGFR Tyrosine Kinase Inhibitor Enhances Radiation Effect in Bladder Cancer Cells.

Blockade of EGFR has been proved useful in enhancing the effect of radiotherapy, but the advantages of new-generation EGFR tyrosine kinase inhibitors (TKI) in radiosensitization are not well known. We used two human bladder cancer cells with wild-type EGFR to study the synergism between irradiation and afatinib (an EGFR/HER2 dual kinase inhibitor) or erlotinib (an EGFR kinase inhibitor). Here, we showed that afatinib has better radiosensitizing effect than erlotinib in increasing cancer cell killing, the percentage of apoptotic cells, and DNA damage. Afatinib is also superior to erlotinib in combining radiation to decrease tumor size, inhibit glucose metabolism, and enhance apoptotic proteins in vivo. Finally, erlotinib suppressed cell growth and induced more DNA damage in bladder cancer cells transfected with HER2 shRNA, but not in control vector-treated cells. In conclusion, concomitant blockade of radiation-activated EGFR and HER2 signaling by a new-generation EGFR TKI better inhibits the growth of bladder cancer cells both in vitro and in vivo. The absence of radiosensitization by EGFR inhibition alone and the greater radiosensitizing effect of EGFR inhibitor in HER2 knocked down cells suggest the synergism between HER2 and EGFR in determining radiosensitivity. The regained radiosensitizing activity of erlotinib implies that with proper HER2 inhibition, EGFR tyrosine kinase is still a potential target to enhance radiotherapy effect in these seemingly unresponsive bladder cancer cells.

Molecular mechanism of progesterone-induced antiproliferation in rat aortic smooth muscle cells.

Previously we demonstrated that progesterone at physiologic levels dose dependently inhibited cell proliferation in cultured rat aortic smooth muscle cells (RASMCs). However, the molecular mechanism underlying of progesterone-induced antiproliferation was not clear. Here we demonstrated that progesterone induced a reduction of the [(3)H]thymidine incorporation into RASMCs during the S-phase of the cell cycle. Western blotting analysis revealed that the protein levels of cyclin A, cyclin E, and cyclin-dependent-kinase (CDK) 2 but not cyclin D1 and CDK4 decreased after progesterone treatment, but those of CDK-inhibitory proteins, p21 and p27, increased. Immunoprecipitation showed that the formations of the CDK2-p21 and CDK2-p27 complex were increased and the assayable CDK2 kinase activity was decreased in the progesterone-treated RASMCs. In contrast, the formations of the CDK4-p21 and CDK4-p27 complex and the assayable CDK4 kinase activity were not changed significantly by progesterone treatment. Pretreatment of RASMCs with a p21 or p27 antisense oligonucleotide reduced the progesterone-induced inhibition of [(3)H]thymidine incorporation into RASMCs. In conclusion, these data suggest that progesterone inhibits RASMCs proliferation by increasing the levels of p21 and p27 protein, which in turn inhibit CDK2 kinase activity, and finally interrupt the cell cycle.

Anti-proliferation effect of 3-amino-2-imino-3,4-dihydro-2H-1,3-benzothiazin-4-one (BJ-601) on human vascular endothelial cells: G0/G1 p21-associated cell cycle arrest.

The aim of this study was to examine the anti-proliferation effect of 3-amino-2-imino-3,4-dihydro-2H-1,3-benzothiazin-4-one (BJ-601) on human vascular endothelial cells and its possible molecular mechanism underlying. Our data showed that BJ-601 at a range of concentrations (0-40 microM) dose- and time-dependently decreased cell number in cultured human dermal microvascular endothelial cells (HDMVECs), but not human fibroblasts. The BJ-601-induced growth inhibition in HDMVECs was reversible. [3H]thymidine incorporation demonstrated that BJ-601 arrested the HDMVECs at the G0/G1 phase of the cell cycle. Western blot analysis revealed that BJ-601 (0-40 microM) dose-dependently increased the levels of the protein p21, but not of p27, p53, cyclins A, D1, D3 and E, cyclin-dependent kinase 2 (CDK2), and CDK4 in HDMVECs. Immunoprecipitation showed that the formation of the CDK2-p21 complex, but not CDK2-p27, CDK4-p21 and CDK4-p27 complexes, was increased in the BJ-601-treated HDMVECs. Kinase assay further demonstrated that CDK2, but not CDK4, kinase activity was decreased in a dose-dependent manner in the BJ-601-treated HDMVECs. Pretreatment of HDMVECs with a p21 antisense oligonucleotide, which blocked the expression of p21 protein, reversed the BJ-601-induced inhibition of [3H]thymidine incorporation into HDMVECs. Moreover, cotreatment of the endothelial cells with protein kinase C (PKC) inhibitor, staurosporine, prevented the BJ-601-induced decrease of [3H]thymidine incorporation into HDMVECs. Administration of BJ-601 dose-dependently inhibited capillary-like tube formation of HDMVECs in Matrigel. In conclusion, these data suggest that BJ-601 inhibits HDMVECs proliferation by increasing the level of p21 protein, which in turn inhibits CDK2 kinase activity, and finally causes retardation of the cell cycle at the G0/G1 phase.

YC-1 inhibits proliferation of human vascular endothelial cells through a cyclic GMP-independent pathway.

This study was designed to investigate the effect of YC-1, 3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole, in human umbilical vein endothelial cells (HUVECs) proliferation and its underlying mechanism. YC-1 at a range of concentrations (5-50 microM) inhibited DNA synthesis and decreased cell number in cultured HUVEC in a dose- and time-dependent manner. YC-1 was not cytotoxic at these concentrations. [3H]thymidine incorporation and flow cytometry analyses revealed that YC-1 treatment decreased DNA synthesis and arrested the cells at the G0/G1 phase of the cell cycle. Western blot analysis demonstrated that YC-1 (5-50 microM) increased the levels of cyclin-dependent kinase (CDK)-inhibitory proteins (CKIs), p21 and p27, but did not induce any significant changes of cyclins and CDKs. In the YC-1-treated HUVEC, the formation of CDK2-p21 complex, but not CDK2-p27 complex, was increased and the assayable CDK2 kinase activity was decreased. These changes were in a dose-dependent manner. In contrast, the formations of CDK4-p21 and CDK4-p27 complex were slightly increased and the assayable CDK4 kinase activity was slightly decreased (if there were any changes). Pretreatment with guanylyl cyclase inhibitors, 1H-(1,2,4)oxadiazolo[4,3-a]quinozalin-1-one (ODQ) and methylene blue, inhibited the YC-1-induced increase of cyclic GMP level, but did not change significantly the magnitude of the YC-1-induced inhibition of thymidine incorporation and cell number in HUVEC. These results indicate that YC-1-induced cell cycle arrest in HUVEC occurred when the cyclin-CDK system was inhibited just as p21 and p27 protein levels were augmented. This YC-1-induced antiproliferation effect in HUVEC is via a cyclic GMP-independent pathway.