Serum-induced Cell Research Articles

Piceatannol Suppresses Breast Cancer Cell Invasion through the Inhibition of MMP-9: Involvement of PI3K/AKT and NF-κB Pathways

Cancer invasion and metastasis are the main causes of treatment failure and death in cancer patients. Piceatannol (3,3',4,5'-tetrahydroxy-trans-stilbene) is a natural analogue of resveratrol. This study investigated the anti-invasive mechanisms of piceatannol in MDA-MB-231 cells. Piceatannol significantly reduced serum-induced cell invasion and migration as well as adhesion without affecting the viability of cells. Furthermore, piceatannol markedly inhibited matrix metalloproteinase-9 (MMP-9) activity and expression at both protein and mRNA levels. Piceatannol attenuated phosphoinisitide-3-kinase (PI3K) and phosphorylation of AKT and mammalian target of rapamycin (mTOR), whereas phosphatase and tensin homologue (PTEN) was increased. Moreover, piceatannol inhibited nuclear factor kappa B (NF-κB) transcriptional activity and DNA binding of NF-κB on MMP-9 promoter. In addition, piceatannol diminished NF-κB nuclear translocation through blocking the inhibitor of NF-κB alpha (IκBα) phosphorylation in the cytoplasm. These results proposed piceatannol as a potential anti-invasive agent by inhibiting MMP-9 involved in PI3K/AKT and NF-κB pathways.

Abstract 3314: Potential role of mitochondrial respiration in serum-induced tumor stem cell differentiation

Abstract Glioblastoma remains the deadliest form of brain tumors. The poor prognosis of glioblastoma patients is associated with a high rate of relapse after therapy. It has been suggested that the presence of cancer stem cells, which are relatively resistant to radiation and chemotherapy, may play a significant role in the recurrence of brain tumor. Understanding the biological property of brain tumor stem cells is important to develop effective therapeutic strategies for glioblastoma. In vitro, glioblastoma stem cells cultured in serum-free medium form self-renewing neurospheres, express the neural stem marker CD133, and are highly tumorigenic. On the other hand, in the presence of fetal bovine serum (FBS), the glioblastoma stem cells tend to undergo differentiation. In this study we used glioblastoma stem cells, NSC11 and NSC23, previously isolated from glioblastoma patients and expressed stem cell markers CD133 and SOX 2, to explore their bioenergetics by monitoring the oxygen consumption as an indication of mitochondrial respiration cultured in serum-free medium in comparison with that incubated in medium containing 5% FBS. We found that NSC11 and NSC23 stem cells exhibited low mitochondrial respiration when cultured in stem cell medium without serum. Upon exposure to 5% fetal bovine serum, mitochondrial respiration increased significantly. Moreover we assessed the protein expression of the mitochondrial respiratory complex (MRC) components in the cells cultured in serum-free medium in comparison with that in medium containing 5% FBS for various lengths of time by western blotting analysis. We observed a marked up-regulation of the protein subunits of MRC complexes I and IV in glioblastoma stem cells when they were exposed to FBS. Analysis of the mRNA expression levels for the mitochondrial DNA-encoded MRC components showed an increase in the expression of these genes, indicating an increase in the mitochondria biogenesis upon the FBS exposure. Based on these preliminary findings, we postulate that maintaining low mitochondrial respiration may be important to maintain the stemness of the glioblastoma stem cells, while the activation of the respiration may promote stem cell differentiation and affect their tumorgenecity. Further studies are required to elucidate the detail molecular pathways governing glioblastoma stem cell self-renewal and differentiation and the mechanistic link to mitochondrial function. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3314. doi:10.1158/1538-7445.AM2011-3314

A Critical Role of Gβγ in Tumorigenesis and Metastasis of Breast Cancer

A growing body of evidence indicates that G protein-coupled receptors (GPCRs) are involved in breast tumor progression and that targeting GPCRs may be a novel adjuvant strategy in cancer treatment. However, due to the redundant role of multiple GPCRs in tumor development, it may be necessary to target a common signaling component downstream of these receptors to achieve maximum efficacy. GPCRs transmit signals through heterotrimeric G proteins composed of Gα and Gβγ subunits. Here we evaluated the role of Gβγ in breast tumor growth and metastasis both in vitro and in vivo. Our data show that blocking Gβγ signaling with Gα(t) or small molecule inhibitors blocked serum-induced breast tumor cell proliferation as well as tumor cell migration induced by various GPCRs in vitro. Moreover, induced expression of Gα(t) in MDA-MB-231 cells inhibited primary tumor formation and retarded growth of existing breast tumors in nude mice. Blocking Gβγ signaling also dramatically reduced the incidence of spontaneous lung metastasis from primary tumors and decreased tumor formation in the experimental lung metastasis model. Additional studies indicate that Gβγ signaling may also play a role in the generation of a tumor microenvironment permissive for tumor progression, because the inhibition of Gβγ signaling attenuated leukocyte infiltration and angiogenesis in primary breast tumors. Taken together, our data demonstrate a critical role of Gβγ signaling in promoting breast tumor growth and metastasis and suggest that targeting Gβγ may represent a novel therapeutic approach for breast cancer.

Anticancer Efficacy of Simvastatin on Prostate Cancer Cells and Tumor Xenografts Is Associated with Inhibition of Akt and Reduced Prostate-Specific Antigen Expression

Prostate cancer is the second-leading cause of cancer-associated death among men in the United States. There has been renewed interest in the potential therapeutic benefits of statins for cancer. Simvastatin, a widely used generic drug for preventing cardiovascular events, is well known for its effects on cellular proliferation and inflammation, two key processes that also determine the rate of tumor growth. Although a growing body of evidence suggests that statins have the potential to reduce the risk of many cancers, there are discrepancies over the pro- and anticancer effects of statins. In the current study, we sought to investigate the effects of simvastatin on the Akt pathway in prostate cancer cells with respect to the regulation of various cell functions in vitro and tumor growth in vivo. Time- and dose-dependent effects of simvastatin on LNCaP (androgen-dependent) and PC3 (androgen-independent) cells indicate that treatment with simvastatin at concentrations as low as 25 μM was sufficient to inhibit serum-stimulated Akt activity. Akin to this, treatment with simvastatin significantly inhibited serum-induced cell migration, invasion, colony formation, and proliferation. Simvastatin-mediated effects on colony formation were rescued by adenovirus-mediated expression of constitutively active Akt (myristoylated Akt) in PC3 cell lines. A PC3 xenograft model performed in nude mice exhibited reduced tumor growth with simvastatin treatment associated with decreased Akt activity and reduced prostate-specific antigen (PSA) levels. Our findings demonstrate the therapeutic benefits of simvastatin for prostate cancer and suggest a link between simvastatin, regulation of Akt activity, and PSA expression in prostate tumors.

Myc-dependent Mitochondrial Generation of Acetyl-CoA Contributes to Fatty Acid Biosynthesis and Histone Acetylation during Cell Cycle Entry

Cell reprogramming from a quiescent to proliferative state requires coordinate activation of multiple -omic networks. These networks activate histones, increase cellular bioenergetics and the synthesis of macromolecules required for cell proliferation. However, mechanisms that coordinate the regulation of these interconnected networks are not fully understood. The oncogene c-Myc (Myc) activates cellular metabolism and global chromatin remodeling. Here we tested for an interconnection between Myc regulation of metabolism and acetylation of histones. Using [(13)C(6)]glucose and a combination of GC/MS and LC/ESI tandem mass spectrometry, we determined the fractional incorporation of (13)C-labeled 2-carbon fragments into the fatty acid palmitate, and acetyl-lysines at the N-terminal tail of histone H4 in myc(-/-) and myc(+/+) Rat1A fibroblasts. Our data demonstrate that Myc increases mitochondrial synthesis of acetyl-CoA, as the de novo synthesis of (13)C-labeled palmitate was increased 2-fold in Myc-expressing cells. Additionally, Myc induced a forty percent increase in (13)C-labeled acetyl-CoA on H4-K16. This is linked to the capacity of Myc to increase mitochondrial production of acetyl-CoA, as we show that mitochondria provide 50% of the acetyl groups on H4-K16. These data point to a key role for Myc in directing the interconnection of -omic networks, and in particular, epigenetic modification of proteins in response to proliferative signals.

Senescence and dysfunction of proximal tubular cells are associated with activated p53 expression by indoxyl sulfate

Various uremic toxins accumulate in patients with chronic renal failure (CRF) and one of them is indoxyl sulfate, which accelerates the progression of CRF through unknown mechanisms. The present study investigates how indoxyl sulfate promotes CRF using the proximal tubular cell line HK-2 and CRF rats. Indoxyl sulfate inhibited serum-induced cell proliferation and promoted the activation of senescence-associated β-galactosidase, a marker of cellular senescence, and the expression of α-smooth muscle actin (α-SMA), a marker of fibrosis, through inducing p53 expression and phosphorylation. Pifithrin-α, p-nitro, a p53 inhibitor, blocked these effects. Indoxyl sulfate evoked reactive oxygen species (ROS), and the antioxidant N-acetylcysteine inhibited indoxyl sulfate-induced p53 expression and phosphorylation, as well as indoxyl sulfate-induced α-SMA expression. We previously demonstrated that although cellular senescence and fibrosis are detectable in the kidneys of CRF rats, the oral adsorbent AST-120 repressed these effects. Here, we found that β-galactosidase, p53 and α-SMA were expressed and colocalized in the renal tubules of CRF rats, whereas AST-120 decreased the expression of these genes. Taken together, these findings indicate that indoxyl sulfate induces the expression and phosphorylation of p53 though ROS production, thus inhibiting cell proliferation and promoting cellular senescence and renal fibrosis.

Weight-adjusted dalteparin for prevention of vascular thromboembolism in advanced pancreatic cancer patients decreases serum tissue factor and serum-mediated induction of cancer cell invasion

The aim of the present study was to assess the role of tissue factor and serum-induced cell invasion in patients with advanced pancreatic cancer (APC). A cohort of 39 patients with APC, without thrombosis, receiving chemotherapy, were entered in a randomized controlled trial (ISRCTN = 76464767) of thromboprevention with weight-adjusted dalteparin (WAD). A total of 19 patients received WAD, the remaining 20 acting as a control group. Serum from baseline and week 8 was analysed for circulating-tissue factor antigen using ELISA. Circulating-tissue factor antigen rose from 324 pg/ml, [interquartile range (IQR) 282-347 pg/ml] to 356 pg/ml, (IQR 319-431 pg/ml) in controls (C), and decreased in the dalteparin-treated group (D) from 336 pg/ml (IQR 281-346 pg/ml) to 303 pg/ml (IQR 274-339 pg/ml). The difference in median percentage change between D and C was statistically significant [-4.0 (D) vs. 4.7 (C); P = 0.005, n = 39]. Serum-induced cellular invasion of MIA-Paca-2 cells in response to patient serum was studied using a Boyden chamber assay in 30 patients (14 WAD and 16 C). The median percentage change between C and D was significant [+54.9 (C) vs. -21.9 (D) P = 0.025, n = 30]. There was a weak correlation between BB-tissue factor reduction and cellular invasion reduction (Spearman) [0.384 (P = 0.037, n = 30)]. APC patients treated with WAD have lower tissue factor antigen levels and attenuated induction of cellular invasion in their blood. These assays may provide useful markers to guide appropriate dalteparin (and other low-molecular weight heparin) dosing schedules to optimize anticancer effects of dalteparin in APC.

Esophageal cancer-related gene 4 is a secreted inducer of cell senescence expressed by aged CNS precursor cells

Mammalian aging is thought to be partially caused by the diminished capacity of stem/precursor cells to undergo self-renewing divisions. Although many cell-cycle regulators are involved in this process, it is unknown to what extent cell senescence, first identified as irreversible growth arrest in vitro, contributes to the aging process. Here, using a serum-induced mouse oligodendrocyte precursor cell (mOPC) senescence model, we identified esophageal cancer-related gene 4 (Ecrg4) as a senescence inducer with implications for the senescence-like state of postmitotic cells in the aging brain. Although mOPCs could proliferate indefinitely when cultured using the appropriate medium (OPC medium), they became senescent in the presence of serum and maintained their senescent phenotype even when the serum was subsequently replaced by OPC medium. We show that Ecrg4 was up-regulated in the senescent OPCs, its overexpression in OPCs induced senescence by accelerating the proteasome-dependent degradation of cyclins D1 and D3, and that its knockdown by a specific short hairpin RNA prevented these phenotypes. We also show that senescent OPCs secreted Ecrg4 and that recombinant Ecrg4 induced OPC senescence in culture. Moreover, increased Ecrg4 expression was observed in the OPCs and neural precursor cells in the aged mouse brain; this was accompanied by the expression of senescence-associated beta-galactosidase activity, indicating the cells' entrance into senescence. These results suggest that Ecrg4 is a factor linking neural-cell senescence and aging.

The Crataegus extract WS ® 1442 inhibits balloon catheter-induced intimal hyperplasia in the rat carotid artery by directly influencing PDGFR-β

Objective Effective systemic drugs against restenosis upon percutaneous transluminal coronary angioplasty (PTCA) are largely lacking. Polyphenols have been suggested to ameliorate post-angioplasty restenosis. Hawthorn ( Crataegus spp.) extracts, which are among the most frequently used herbal medicinal products against mild forms of congestive heart failure, contain polyphenols, but have not been investigated in this context. We aimed to assess the potential of the hawthorn extract WS ® 1442 to prevent balloon catheter-induced intimal hyperplasia and to elucidate the underlying mechanisms. Methods We analyzed the effects of WS ® 1442 on serum-induced vascular smooth muscle cell (VSMC) and endothelial cell (EC) growth and migration, growth factor-induced proliferation, growth factor receptor activity, and neointima formation in the rat carotid artery model. Results WS ® 1442 (100 μg/ml) decreased VSMC migration by 38% and proliferation by 44%, whereas EC migration and proliferation were unaltered. The extract inhibited VSMC DNA synthesis induced by platelet-derived growth factor (PDGF) (IC 50: 47 μg/ml), but not that of basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF). Along this line, WS ® 1442 blocked recombinant human PDGF receptor (PDGFR)-β kinase activity (IC 50: 1.4 μg/ml) and decreased PDGFR-β activation and extracellular signal-regulated kinase (ERK) activation in VSMCs. In rats, orally administered WS ® 1442 significantly reduced neointima formation after balloon catheter dilatation of the carotid artery. Conclusion WS ® 1442 inhibits migration and proliferation of VSMCs, but not of ECs, and reduces balloon catheter-evoked neointima formation probably through inhibition of PDGFR-β. Thus, the present study suggests a novel adjunct pharmacological strategy to prevent angioplasty-related restenosis.

Calcitonin gene‐related peptide increases proliferation of human HaCaT keratinocytes by activation of MAP kinases

Psoriasis is a chronic disease characterized by keratinocyte hyperproliferation and inflammation. It has been demonstrated that the expression of calcitonin gene-related peptide (CGRP) is elevated in psoriasis lesions and CGRP-containing neuropeptide nerve fibers are denser in the psoriatic epidermis. CGRP has been previously described to influence proliferation of several cell types, such as Schwann cell, tracheal epithelial cells, and human gingival fibroblasts. In the present study, we determined the effect of CGRP on HaCaT keratinocyte proliferation and the role of mitogen-activated protein kinases (MAPKs) in CGRP induced keratinocyte proliferation. Our data indicate CGRP increased [(3)H]-thymidine incorporation and MTT activity of HaCaT in a concentration-dependent manner. CGRP also enhanced serum-induced HaCaT cell proliferation. HaCaT cells cultured with CGRP had a significant increase in phosphorylated ERK1/2, p38 and JNK, and CGRP induced DNA synthesis was inhibited by PD 98059 or SB 203580, selective inhibitors of MAP kinase kinase (MEK, which is upstream from ERK) and p38, respectively. These findings suggest that HaCaT cell proliferate in response to CGRP, which is mediated by phosphorylation of ERK1/2 and p38 MAPK.

Anti-Invasive and Anti-Angiogenic Effects of Xanthohumol and Its Synthetic Derivatives

Abstract － Invasion and metastasis is the main cause of cancer mortality. Angiogenesis is a prerequisite for the tumor growth and metastasis. Matrix metalloproteinases (MMPs) are the key enzymes playing in the invasive growth and metastasis of cancer as well as angiogenesis. Xanthohumol, a prenylated chalcone of the Hop plant (Humulus lupulus L ), has been reported to suppress cancer invasion and angiogenesis. In the present study, we investigated the antiinvasive effects of xanthohumol (1) and its synthetic derivatives, 4'- O -methylxanthohumol SEM ether (2), xanthohumol C (3), and xanthohumol C MOM ether (4) in relation to MMP expression in HT-1080 human fibrosarcoma cells. The compound 1 and its derivative, 3 and 4, significantly inhibited serum-induced HT-1080 cell invasion, and 12- O -tetradecanoylphorbol-13-acetate (TPA)-enhanced activity and expression level of MMP-2 and MMP-9 in a concentration-dependant manner. In addition, they inhibited TPA-enhanced expression of MT1-MMP with relatively weak inhibition in tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2 level. The compound 1 significantly decreased the cell viability, whereas the derivatives, 2 and 3 showed no cytotoxicity, and compound 4 showed slight cytotoxicity in the cells. Furthermore, in a chick chorioallantoic membrane (CAM) assay, the derivatives 3 and 4 dose-dependently suppressed vascular endothelial growth factor (VEGF)-induced angiogenesis, which is similar to that of compound 1. Taken together, the results indicate that compounds 3 and 4 may be valuable anti-angiogenic agents in the treatment of chronic diseases such as cancer and inflammation working through suppression of MMP-2 and MMP-9.Keywords: Xanthohumol, Xanthohumol C, Cancer cell invasion, Angiogenesis, Matrix metalloproteinase

Integrin α5β1 Mediates Attachment, Migration, and Proliferation in Human Retinal Pigment Epithelium: Relevance for Proliferative Retinal Disease

The aim of this study was to determine the expression and localization of integrin alpha5beta1 in human retinal pigment epithelium (RPE) and its ability to modulate RPE cell attachment, proliferation, migration, and F-actin cytoskeleton distribution. Expression and localization of alpha5beta1 were analyzed on human RPE by immunoblot/immunofluorescence. Polarized secretion of fibronectin was measured. RPE attachments to different substrates were determined using cell attachment screening kits. BrdU incorporation and wound-healing assays were used to test hfRPE proliferation and migration. F-actin cytoskeleton was visualized with phalloidin. Integrin alpha5beta1 was detected in native adult and fetal human RPE. The alpha5-subunit is predominantly localized at the apical membrane of hfRPE, whereas the beta1-subunit is uniformly detected at the apical/basolateral membranes. The authors also found that hfRPE cultures secrete significant amounts of fibronectin to the apical bath. JSM6427, a specific integrin alpha5beta1 antagonist, significantly inhibited hfRPE cell attachment to fibronectin, but not laminin, or collagen I or IV. JSM6427 also showed a strong inhibitory effect on bFGF, PDGF-BB, and serum-induced cell migration and proliferation. Furthermore, JSM6427 induced significant disruption of the F-actin cytoskeleton of dividing RPE cells but had no effect on quiescent cells. The apical localization of alpha5beta1 and the secretion of fibronectin to the apical bath suggest the presence of an autocrine loop that can guide the migration of RPE. The strong inhibitory effects of JSM6427 on human RPE cell attachment, proliferation, and migration is probably mediated by F-actin cytoskeletal disruption in proliferating cells and suggests a potential clinical use of this compound in proliferative retinopathies.

Involvement of Akt1/protein kinase Bα in tumor conditioned medium-induced endothelial cell migration and survival in vitro

Endothelial cell migration and survival might be called "major angiogenic responses". Tumor conditioned medium (CM) has been widely used to stimulate endothelial cells to form capillary-like structures in angiogenesis models in vitro. However, the molecular events triggered by tumor CM are not fully understood. Here, we examined the effects of the CM from human lung carcinoma cell lines A549 and SPC-A-1 on cultures of primary human umbilical veins endothelial cells (HUVECs). After treatment of HUVECs with the CM, cell migration was assessed by wound-healing assay, cell viability was evaluated by XTT assay, and apoptosis and cell death of HUVECs was analyzed by flow cytometry. Phosphorylation of Akt was assessed by Western blotting. To dissect the direct role of Akt, small interfering RNA (siRNA) against Akt1 was used. Both A549 and SPC-A-1 CM significantly stimulated cell migration. However, only A549 CM promoted cell viability and inhibited low serum-induced apoptosis and cell death of HUVECs, but SPC-A-1-CM showed no effects on survival of HUVECs. Meanwhile, A549 CM was found to be able to induce much more phosphorylation of Akt compared to SPC-A-1 CM treated group. The inhibitor of PI3K (wortmaninn) or Akt1 siRNA blocked A549 CM-induced migration and survival of HUVECs. These results indicated that the angiogenic effects of A549 CM are largely mediated through activation of the PI3K-Akt in endothelial cells, and that the Akt1 is crucial in this process, which may provide a therapeutic target for decreasing tumor angiogenesis.

Effects of a trichothecene, T-2 toxin, on proliferation and steroid production by porcine granulosa cells

Fusarium mycotoxins, such as trichothecenes and zearalenone, are produced by molds and contaminate a large variety of grains and feedstuffs worldwide. Mycotoxins of Fusarium fungi include the trichothecenes, deoxynivalenol and T-2 toxin (T2), and zearalenone, and have been implicated in poor reproductive performance in pigs. However, direct ovarian effects of T2 toxin have not been reported. Therefore, porcine granulosa cells (GC) from small follicles (1–5 mm) were cultured for 2 days in 5% fetal bovine serum and 5% porcine serum-containing medium followed by 2 days in serum-free medium containing various doses of FSH, insulin-like growth factor-I and T2 (at various doses/combinations) to evaluate the influence of T2 on steroid production and cell proliferation. T2 at 1, 3, 30 and 300 ng/mL completely inhibited FSH plus IGF-I-induced estradiol production, whereas 0.3 ng/mL of T2 inhibited estradiol production by 40%. Progesterone production was less sensitive to the inhibitory effects of T2 with 0.3 ng/mL having no effect and 1 ng/mL inhibiting progesterone production by only 30%. At 30 and 300 ng/mL, T2 completely inhibited FSH plus IGF-I-induced progesterone production. The impact of T2 on the dose–response to IGF-I (0, 3, 10 and 30 ng/mL) was also evaluated; T2 blunted the stimulatory effect of 3–30 ng/mL of IGF-I on steroid production and cell proliferation. Serum-induced granulosa cell proliferation was decreased ( P < 0.05) by 40% after 1 day and by 56% after 2 days of T2 treatment. The present studies indicate for the first time that T2 may be able to alter in growth of the granulosa layer within ovarian follicles in addition to their effect on steroidogenesis. In conclusion, T2 has potent direct dose-dependent effects on granulosa cell proliferation and steroidogenesis. These direct ovarian effects could be one mechanism whereby contaminating Fusarium mycotoxins in feedstuffs could impact reproductive performance in swine.

Early effects of mood stabilizers on the Akt/GSK-3β signaling pathway and on cell survival and proliferation

Lithium, some of the anticonvulsants, and several second-generation antipsychotic drugs are common medications widely prescribed to treat bipolar disorder. Molecular targets and cellular events that mediate their effects have been described for these drugs but are only partially unraveled. Few comparative studies have been performed. We evaluated seven mood stabilizers (MS) in the same in vitro system and found several differences and similarities in their cellular mechanisms (proliferation and cell survival). As some MS were previously shown to activate the Akt/GSK-3beta axis, this pathway was explored for other drugs. The SH-SY5Y cells were cultured in RPMI-1640 medium. Effects of MS drugs on serum-induced cell proliferation and on slowing of cell death were analyzed. Phosphorylation and expression of Akt-1 and GSK-3beta mRNA and protein were assessed for the seven drugs as well. Lithium, Valproate, Olanzapine, and Clozapine enhance proliferation and protect cells against serum withdrawal-induced injury. These drugs also activate Akt-1 and GSK-3beta phosphorylation. Interestingly, gene expression of Akt-1 mRNA and protein, but not GSK-3beta, was increased. The other drugs Lamotrigine, Haloperidol, and Carbamazepine did not affect cellular events nor activate Akt/GSK-3beta axis. Valproate and atypical antipsychotics (Olanzapine and Clozapine) regulate SH-SY5Y cell proliferation and survival, activate the Akt/GSK-3beta axis, and stimulate gene expression of Akt-1 mRNA and protein, as does Lithium. The other medications have no effect. The study shows the importance of the Akt/GSK-3 axis in MS actions but also pinpoints a different dependence of these drugs on this signaling axis.

Rat Prolactinoma Cell Growth Regulation by Epidermal Growth Factor Receptor Ligands

Epidermal growth factor (EGF) regulates pituitary development, hormone synthesis, and cell proliferation. Although ErbB receptor family members are expressed in pituitary tumors, the effects of EGF signaling on pituitary tumors are not known. Immunoprecipitation and Western blot confirmed EGF receptor (EGFR) and p185(c-neu) protein expression in GH3 lacto-somatotroph but not in adrenocorticotropic hormone-secreting AtT20 pituitary tumor cells. EGF (5 nmol/L) selectively enhanced baseline ( approximately 4-fold) and serum-induced (>6-fold) prolactin (PRL) mRNA levels, whereas gefitinib, an EGFR antagonist, suppressed serum-induced cell proliferation and Pttg1 expression, blocked PRL gene expression, and reversed EGF-mediated somatotroph-lactotroph phenotype switching. Downstream EGFR signaling by ERK, but not phosphoinositide-3-kinase or protein kinase C, mediated the gefitinib response. Tumors in athymic mice implanted s.c. with GH3 cells resulted in weight gain accompanied by increased serum PRL, growth hormone, and insulin growth factor 1. Gefitinib decreased tumor volumes and peripheral hormone levels by approximately 30% and restored normal mouse body weight patterns. Mice treated with gefitinib exhibited decreased tumor tissue ERK1/2 phosphorylation and down-regulated tumor PRL and Pttg1 mRNA abundance. These results show that EGFR inhibition controls tumor growth and PRL secretion in experimental lacto-somatotroph tumors. EGFR inhibitors could therefore be useful for the control of PRL secretion and tumor load in prolactinomas resistant to dopaminergic treatment, or for those prolactinomas undergoing rare malignant transformation.

Inhibitory effects of BIO-1211 on bronchoconstriction and neutrophil adhesion in rats

To determine the inhibitory effects of BIO-1211, a very late antigen-4 (vla-4) antagonist, on bronchoconstriction and neutrophil adhesion in rats. For evaluating ovalbumin-induced bronchoconstriction in the sensitized rats, the changes in lung resistance (RL) and lung dynamic compliance (C(dyn)) were determined after antigen challenge. Neutrophils from the rats were used to determine fibronectin and serum-induced cell adhesion. The effect of BIO-1211 on wheezing was determined after inhalation of histamine and acetylcholine in guinea pigs. BIO-1211 aerosol at 1, 3 and 10 mg/ml significantly inhibited the changes in lung resistance and lung dynamic compliance after antigen challenge in the sensitized rats in a dose-dependent manner. BIO-1211 at 25, 50, 100 and 200 microgram/ml inhibited the fibronectin-induced neutrophil adhesion by 23.5%, 24.6%, 61.4% and 58.1%, respectively, and serum-induced adhesion by 29.9%, 35.9%, 35.3% and 15.4%, respectively. Inhalation of 10 mg/ml BIO-1211 did not show any protection against histamine and acetylcholine-induced bronchoconstriction. BIO-1211 inhibits bronchoconstriction and neutrophil adhesion, which may be associated with its effect against bronchoconstriction in rats.

PDK1 Regulates Cell Proliferation and Cell Cycle Progression through Control of Cyclin D1 and p27Kip1 Expression

PDK1 (3-phosphoinositide-dependent protein kinase 1) is a key mediator of signaling by phosphoinositide 3-kinase. To gain insight into the physiological importance of PDK1 in cell proliferation and cell cycle control, we established immortalized mouse embryonic fibroblasts (MEFs) from mice homozygous for a "floxed" allele of Pdk1 and from wild-type mice. Introduction of Cre recombinase by retrovirus-mediated gene transfer resulted in the depletion of PDK1 in Pdk1(lox/lox) MEFs but not in Pdk1(+/+) MEFs. The insulin-like growth factor-1-induced phosphorylation of various downstream effectors of PDK1, including Akt, glycogen synthase kinase 3, ribosomal protein S6, and p70 S6 kinase, was markedly inhibited in the PDK1-depleted (Pdk1-KO) MEFs. The rate of serum-induced cell proliferation was reduced; progression of the cell cycle from the G(0)-G(1) phase to the S phase was delayed, and cell cycle progression at G(2)-M phase was impaired in Pdk1-KO MEFs. These cells also manifested an increased level of p27(Kip1) expression and a reduced level of cyclin D1 expression during cell cycle progression. The defect in cell cycle progression from the G(0)-G(1) to the S phase in Pdk1-KO MEFs was rescued by forced expression of cyclin D1, whereas rescue of the defect in G(2)-M progression in these cells required both overexpression of cyclin D1 and depletion of p27(Kip1) by RNA interference. These data indicate that PDK1 plays an important role in cell proliferation and cell cycle progression by controlling the expression of both cyclin D1 and p27(Kip1).

CAMP Inhibits Cell Migration by Interfering with Rac-induced Lamellipodium Formation

Cell migration is critical for animal development and physiological as well as pathological responses. One important step during cell migration is the formation of lamellipodia at the leading edge of migrating cells. Here we report that the second messenger cAMP inhibits the migration of mouse embryonic fibroblast cells and mouse breast tumor cells. cAMP acts downstream of the small GTPase Rac and interferes with the formation of lamellipodia. Moreover, cAMP decreases the phosphorylation of the myosin light chain at the leading edge of cells and increases the phosphorylation of the vasodilator-stimulated phosphoprotein. Together with our previous report of a positive role of another second messenger, cGMP, in lamellipodium formation, our data indicate that cAMP and cGMP play opposite roles in modulating lamellipodium formation.

Role of Cytochrome P450 2C Epoxygenases in Hypoxia-Induced Cell Migration and Angiogenesis in Retinal Endothelial Cells

Cytochrome P450 (CYP) epoxygenase-derived epoxyeicosatrienoic acids (EETs) elicit cell proliferation and promote angiogenesis. The aim of this study was to determine the expression of CYP epoxygenases in the bovine retina and the potential role of EETs in hypoxia-induced angiogenesis in bovine retinal endothelial cells. Bovine retinal endothelial cells were cultured under normoxic (21% O(2)) or hypoxic (1% O(2)) conditions, and CYP2C expression was determined by Western blot analysis. The effect of hypoxia on EET levels was determined by LC-MS/MS. Cell migration (Transwell filter assays) and endothelial cell tube formation (on basement membrane matrix) were assessed in vitro in the absence and presence of pharmacologic inhibitors and CYP2C antisense oligonucleotides. Bovine retinal endothelial cells expressed CYP2C protein in culture and generated detectable levels of EETs under basal conditions. Hypoxia (6-48 hours) enhanced CYP2C protein expression (2-fold) and EET formation (1.5-fold). Moreover, endothelial cells preexposed to hypoxia demonstrated an increase in serum-induced cell migration that was sensitive to the CYP2C inhibitors sulfaphenazole and MS-PPOH and the EET antagonist 14,15-epoxyeicosa-5(Z)-enoic acid. Furthermore, preventing the hypoxia-induced expression of CYP2C (antisense oligonucleotides) suppressed hypoxia-induced cell migration. In an in vitro angiogenesis model, the preexposure of endothelial cells to hypoxia increased CYP2C expression and enhanced endothelial tube formation, which was blocked by the EET antagonist and by the CYP2C antisense oligonucleotides. Taken together, these data indicate that CYP2C-derived EETs are implicated in angiogenesis by retinal endothelial cells, especially under hypoxic conditions.