Induces Cell Survival Research Articles

Abstract 1390: In utero estrogenic exposures increase tamoxifen resistance in a new pre-clinical model of estrogen receptor positive breast cancer.

Abstract Maternal estrogenic exposures during pregnancy increase breast cancer risk among daughters in humans and in animal studies, possibly through epigenetic mechanisms. In addition, our findings obtained using systems biology tools to analyze mRNA microarray data suggest that in utero estrogenic exposures reduce the efficacy of antiestrogen treatment. Here we tested whether development of tamoxifen (TAM) resistance is pre-programmed in the offspring by maternal exposure to estradiol during pregnancy. Pregnant rats were exposed either to 0 or 0.1 ppm ethinyl estradiol (EE2) during pregnancy, and their offspring were treated with DMBA to induce ER+ mammary tumors. Untreated mammary tumors in the EE2 offspring and in women who subsequently recurred (in Loi dataset), exhibited reduced expression of genes in the ATF6 pathway of unfolded protein response (UPR), including an apoptosis-inducing gene CHOP compared with tumors in the control rats or in women who did not recur. In addition, gene microarray analysis identified SEMA3b (p<.012) as down-regulated and KAL1 (p<.02) as up-regulated in the mammary tumors in the EE2 offspring and in TAM resistant LCC9 human breast cancer cells. SEMA3b is a tumor suppressor, perhaps because it induces apoptosis through Akt-mediated pathway, and is found to be methylated in clinical breast cancer and LCC9 cells. In turn, TGF-β regulated KAL1 gene is overexpressed in breast cancer and suggested to induce cell survival and cancer metastasis. TAM treatment (15 mg/kg TAM via feed) was started when first tumor reached a size of 1.3±0.2 cm in diameter. In rats that exhibited a TAM-resistant tumor, valproic acid (HDAC inhibitor) and hydralazine (DNMT inhibitor) were added as a 2nd line treatment. Control rats were more likely to exhibit complete response to TAM (54%) than in utero EE2 exposed rats (38%), and de novo resistance was also lower in the controls (38%) than in the EE2 group (53%). Acquired resistance (re-growth after a complete response to TAM), characterized by over-expression of UPR gene GRP78, was seen in 23% of the tumors in the control and 42% in the EE2 group (p<0.007). Adding HDACi-DNMTi as a 2nd line of treatment significantly reduced de novo (from 53% to 19%, p<0.001) and acquired TAM resistance (from 42% to 6%, p<0.001) in the EE2 offspring, but did not affect TAM resistance in the controls. Treatment with HDACi-DNMTi also reversed the changes in SEMA3b and KAL1 in the rat tumors and reversed TAM resistance in LCC9 cells. Our findings suggest that in utero estrogenic exposures increase TAM resistance by inducing epigenetic changes leading to down-regulation of specific tumor suppressor genes and up-regulation of pro-survival genes. These changes could be reversed by adding HDACi-DNMTi to TAM treatment. Our results may have important clinical implications for treatment of antiestrogen refractory ER+ breast cancer. Citation Format: Nguyen Nguyen, Anni Warri, Robert Clarke, Katherine Cook, Idalia Cruz, Sonia de Assis, Dominic Kim, Jin Lu, Alan Zwart, Jason Xuan, Leena Hilakivi-Clarke. In utero estrogenic exposures increase tamoxifen resistance in a new pre-clinical model of estrogen receptor positive breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1390. doi:10.1158/1538-7445.AM2013-1390

Abstract 4108: SGEF is overexpressed in glioblastoma and mediates TWEAK-Fn14 induced cell survival.

Abstract Glioblastoma (GB) is the highest grade and most common form of primary adult brain tumors. Despite surgical removal followed by concomitant radiation and chemotherapy with the alkylating agent temozolomide (TMZ), GB tumors develop treatment resistance and recur, invading brain tissue. Impaired response to treatment occurs rapidly conferring a median survival of just fifteen months. Thus, it is necessary to identify the genetic and signaling mechanisms that promote tumor resistance and spread in order to develop targeted therapies to combat this refractory setting. Our lab has previously published a role for the TWEAK-Fn14 ligand-receptor system in GB cell invasiveness and survival. Here we report that SGEF, a RhoG specific guanine nucleotide exchange factor (GEF), is overexpressed in GB tumors and we hypothesize that SGEF plays an important role in promoting TWEAK-Fn14 mediated glioma invasion and survival. We show that upon TWEAK binding to Fn14, SGEF is recruited to the Fn14 cytoplasmic tail. The Fn14-SGEF interaction requires TRAF2 recruitment and leads to activation of Rac1. Importantly, SGEF mRNA expression is elevated in TMZ-resistant primary GB tumor grafts compared to those with known TMZ sensitivity. SGEF mRNA and protein expression are regulated by the TWEAK-Fn14 signaling axis in an NF-κB dependent manner and inhibition of SGEF expression via shRNA shutdown sensitizes glioma cells to TMZ-induced apoptosis and impairs colony formation following TMZ insult. Furthermore, gene expression analysis of SGEF depleted GB cells revealed impaired expression of a network of DNA repair and survival genes including ATM, ATR, BRCA2, and XIAP among others, as well as increased expression of the pro-apoptotic gene BAD. Understanding the role of SGEF in promoting chemotherapeutic resistance may direct the development of novel targeted therapeutics for TMZ refractory, invasive GB cells. Citation Format: Shannon P. Fortin, Ian T. Mathews, Jonathan Rollo, Julianna T.D. Ross, Marc H. Symons, Jann N. Sarkaria, Nhan L. Tran. SGEF is overexpressed in glioblastoma and mediates TWEAK-Fn14 induced cell survival. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4108. doi:10.1158/1538-7445.AM2013-4108

Increased protein synthesis of IRES containing mRNAs, that induce cell survival and proliferation, by the daidzein metabolite equol may contribute to breast cancer malignancy.

The effects of soy isoflavones on established breast cancer remain to be understood. We recently reported that dietary daidzein increased primary mammary tumor growth and metastasis, and upregulated eukaryotic protein synthesis initiation factors (eIF) eIF4G and eIF4E. The increased eIF expression in tumor extracts of mice after daidzein diets was associated with protein expression of mRNAs with internal ribosome entry sites (IRES). Results with metastatic cancer cell lines show that the effects of daidzein in vivo can be recapitulated by its metabolite equol. Equol increased metastatic cancer cell viability and up‐regulated gene and protein expression of the transcription factor c‐Myc. In vitro, equol, but not daidzein, up‐regulated eIF4G without affecting eIF4E or its regulator, 4E‐BP, levels. This elevated eIF4G was not associated with eIF4E or 4E‐BP in cap affinity chromatography assays or co‐immunoprecipitations. In dual luciferase assays, IRES‐dependent protein synthesis was increased by equol. As shown by western blotting and polysomal associations, equol specifically increased the expression of IRES‐containing mRNAs of cancer promoting molecules. Therefore, upregulation of eIF4G by equol may result in increased translation of pro‐cancer mRNAs with IRESs and, thus, promote cancer malignancy. Supported by US Army/BCRP W81XWH‐11–1‐0199 to CD and NIH/NIGMS SC3GM084824 to SD.

Transcriptional regulation of cardiac cell death and survival signaling by helium postconditioning in a rat model of regional cardiac ischemia/reperfusion

Helium is a non‐anesthetic, noble gas, which has long been used in humans without deleterious side effects. In animal models of regional myocardial ischemia/reperfusion (I/R), helium inhalation during early reperfusion (postconditioning) reduces infarct size. To gain mechanistic insight into this process we investigated the expression of genes involved in cell death and survival pathways after helium postconditioning.Male rats (n=8 per group) were subjected to ischemia, I/R, or I/R and 15 min of 70% helium at the onset of reperfusion. The sham group (Sham) did not undergo I/R. Gene expression profiles related to necrosis, apoptosis and autophagy were assayed with qRT‐PCR using PCR arrays. Data were expressed as fold increase or decrease versus the I/R group.Helium postconditioning caused upregulation of genes involved in necrosis (17 of 23) and pro‐apoptosis (18 of 25). Simultaneously, 4 of 23 (necrosis) and 7 of 25 genes (pro‐apoptosis) were downregulated. The majority of anti‐apoptotic genes (9 of 11) and genes involved in autophagy (24 of 32) was upregulated after helium postconditioning.These data suggest that helium postconditioning induces cell survival pathways to such an extent that execution of cell death programs is partially abrogated or offset, leading to a reduction in infarct size.

MiR-21 confers cisplatin resistance in gastric cancer cells by regulating PTEN

Resistance to chemotherapy is a major obstacle for the effective treatment of cancers. The mechanism of chemo-resistance is still poorly understood, however, mounting evidence supports a role for microRNAs (miRNAs) in modulating key cellular pathways mediating response to chemotherapy. microRNA-21 (miR-21) has been implicated in many cancers and contributed to chemo-resistance, but its role in gastric cancer drug resistance still remains unexplored. The aim of this study was to investigate whether miR-21 mediated resistance of the gastric cancer cell line SGC7901 to the chemotherapeutic agent cisplatin (DDP). Our study found that the expression of miR-21 upregulated in the cisplatin resistant cell line SGC7901/DDP compared to its parental line SGC7901. Moreover, over-expression of miR-21 significantly decreased antiproliferative effects and apoptosis induced by cisplatin, while knockdown of miR-21 dramatically increased antiproliferative effects and apoptosis induction by cisplatin. In addition, miR-21 induced cell survival and cisplatin resistance through downregulating the expression of phosphatase and tension homolog deleted on chromosome 10 (PTEN) and activation of Akt pathway. Inhibition of Akt using PI3K inhibitor LY 294002 could abrogate miR-21 induced cell survival. These results suggest that miR-21 may provide a novel mechanism for understanding cisplatin resistance in gastric cancer by modulating PTEN/PI3K/Akt pathway.

Insulin-like Growth Factor (IGF) Signaling Requires αvβ3-IGF1-IGF Type 1 Receptor (IGF1R) Ternary Complex Formation in Anchorage Independence, and the Complex Formation Does Not Require IGF1R and Src Activation

Integrin αvβ3 plays a role in insulin-like growth factor 1 (IGF1) signaling (integrin-IGF1 receptor (IGF1R) cross-talk) in non-transformed cells in anchorage-dependent conditions. We reported previously that IGF1 directly binds to αvβ3 and induces αvβ3-IGF1-IGF1R ternary complex formation in these conditions. The integrin-binding defective IGF1 mutant (R36E/R37E) is defective in inducing ternary complex formation and IGF signaling, whereas it still binds to IGF1R. We studied if IGF1 can induce signaling in anchorage-independent conditions in transformed Chinese hamster ovary cells that express αvβ3 (β3-CHO) cells. Here we describe that IGF1 signals were more clearly detectable in anchorage-independent conditions (polyHEMA-coated plates) than in anchorage-dependent conditions. This suggests that IGF signaling is masked by signals from cell-matrix interaction in anchorage-dependent conditions. IGF signaling required αvβ3 expression, and R36E/R37E was defective in inducing signals in polyHEMA-coated plates. These results suggest that αvβ3-IGF1 interaction, not αvβ3-extracellular matrix interaction, is essential for IGF signaling. Inhibitors of IGF1R, Src, AKT, and ERK1/2 did not suppress αvβ3-IGF-IGF1R ternary complex formation, suggesting that activation of these kinases are not required for ternary complex formation. Also, mutations of the β3 cytoplasmic tail (Y747F and Y759F) that block β3 tyrosine phosphorylation did not affect IGF1R phosphorylation or AKT activation. We propose a model in which IGF1 binding to IGF1R induces recruitment of integrin αvβ3 to the IGF-IGF1R complex and then β3 and IGF1R are phosphorylated. It is likely that αvβ3 should be together with the IGF1-IGF1R complex for triggering IGF signaling.

MicroRNA-221 Induces Cell Survival and Cisplatin Resistance through PI3K/Akt Pathway in Human Osteosarcoma

BackgroundMicroRNAs are short regulatory RNAs that negatively modulate protein expression at a post-transcriptional and/or translational level and are deeply involved in the pathogenesis of several types of cancers. Specifically, microRNA-221 (miR-221) is overexpressed in many human cancers, wherein accumulating evidence indicates that it functions as an oncogene. However, the function of miR-221 in human osteosarcoma has not been totally elucidated. In the present study, the effects of miR-221 on osteosarcoma and the possible mechanism by which miR-221 affected the survival, apoptosis, and cisplatin resistance of osteosarcoma were investigated.Methodology/Principal FindingsReal-time quantitative PCR analysis revealed miR-221 was significantly upregulated in osteosarcoma cell lines than in osteoblasts. Both human osteosarcoma cell lines SOSP-9607 and MG63 were transfected with miR-221 mimic or inhibitor to regulate miR-221 expression. The effects of miR-221 were then assessed by cell viability, cell cycle analysis, apoptosis assay, and cisplatin resistance assay. In both cells, upregulation of miR-221 induced cell survival and cisplatin resistance and reduced cell apoptosis. In addition, knockdown of miR-221 inhibited cell growth and cisplatin resistance and induced cell apoptosis. Potential target genes of miR-221 were predicted using bioinformatics. Moreover, luciferase reporter assay and western blot confirmed that PTEN was a direct target of miR-221. Furthermore, introduction of PTEN cDNA lacking 3′-UTR or PI3K inhibitor LY294002 abrogated miR-221-induced cisplatin resistance. Finally, both miR-221 and PTEN expression levels in osteosarcoma samples were examined by using real-time quantitative PCR and immunohistochemistry. High miR-221 expression level and inverse correlation between miR-221 and PTEN levels were revealed in osteosarcoma tissues.Conclusions/SignificanceThese results for the first time demonstrate that upregulation of miR-221 induces the malignant phenotype of human osteosarcoma whereas knockdown of miR-221 reverses this phenotype, suggesting that miR-221 could be a potential target for osteosarcoma treatment.

APRIL Binding to BCMA Activates a JNK2–FOXO3–GADD45 Pathway and Induces a G2/M Cell Growth Arrest in Liver Cells

The TNF superfamily ligands APRIL and BAFF bind with different affinity to two receptors, BCMA and TACI, and induce cell survival and/or proliferation, whereas BAFF also binds specifically to BAFFR. These molecules were considered specific for the immune system. Recently, however, they were also found in epithelial and mesenchymal noncancerous and cancerous tissues and cell lines. In this article, we report that hepatocellular carcinoma (HCC) cell lines HepG2 and Hep3B and HCC specimens express APRIL and BAFF and their receptors BCMA and BAFFR, but not TACI; APRIL/BCMA is enhanced in HCC, compared with normal liver tissue. In contrast to previous reports, APRIL binding to BCMA decreases cell proliferation by inducing G(2)/M cell cycle arrest, whereas BAFF has no effect on cell growth. HCC cells therefore represent a rare system in which these two ligands (APRIL and BAFF) exert a differential effect and may serve as a model for specific APRIL/BCMA actions. We show that the effect of APRIL is mediated via BCMA, which does not activate the classical NF-κB pathway, whereas it induces a novel signaling pathway, which involves JNK2 phosphorylation, FOXO3A activation, and GADD45 transcription. In addition, JNK2 mediates the phosphorylation of Akt, which is activated but does not participate in the antiproliferative effect of APRIL. Furthermore, transcriptome analysis revealed that APRIL modifies genes specifically related to cell cycle modulation, including MCM2/4/5/6, CDC6, PCNA, and POLE2. Our data, therefore, identify a novel APRIL/BCMA signaling pathway in HCC and suggest that APRIL could have a pleiotropic role in tumor biology.

Docosahexaenoic Acid Signaling Modulates Cell Survival in Experimental Ischemic Stroke Penumbra and Initiates Long-Term Repair in Young and Aged Rats

BackgroundDocosahexaenoic acid, a major omega-3 essential fatty acid family member, improves behavioral deficit and reduces infarct volume and edema after experimental focal cerebral ischemia. We hypothesize that DHA elicits neuroprotection by inducing AKT/p70S6K phosphorylation, which in turn leads to cell survival and protects against ischemic stroke in young and aged rats.Methods and ResultsRats underwent 2 h of middle cerebral artery occlusion (MCAo). DHA, neuroprotectin D1 (NPD1) or vehicle (saline) was administered 3 h after onset of stroke. Neurological function was evaluated on days 1, 2, 3, and 7. DHA treatment improved functional recovery and reduced cortical, subcortical and total infarct volumes 7 days after stroke. DHA also reduced microglia infiltration and increased the number of astrocytes and neurons when compared to vehicle on days 1 and 7. Increases in p473 AKT and p308 AKT phosphorylation/activation were observed in animals treated with DHA 4 h after MCAo. Activation of other members of the AKT signaling pathway were also observed in DHA treated animals including increases in pS6 at 4 h and pGSK at 24 h. DHA or NPD1 remarkably reduced total and cortical infarct in aged rats. Moreover, we show that in young and aged rats DHA treatment after MCAo potentiates NPD1 biosynthesis. The phosphorylation of p308 AKT or pGSK was not different between groups in aged rats. However, pS6 expression was increased with DHA or NPD1 treatment when compared to vehicle.ConclusionsWe suggest that DHA induces cell survival, modulates the neuroinflammatory response and triggers long term restoration of synaptic circuits. Both DHA and NPD1 elicited remarkable protection in aged animals. Accordingly, activation of DHA signaling might provide benefits in the management of ischemic stroke both acutely as well as long term to limit ensuing disabilities.

Biphasic Dose-Dependent Effect of Lithium Chloride on Survival of Human Hormone-Dependent Breast Cancer Cells (MCF-7)

Lithium, the first element of Group I in the periodic system, is used to treat bipolar psychiatric disorders. Lithium chloride (LiCl) is a selective inhibitor of glycogen synthase kinase-3β (GSK-3β), a serine/threonine kinase that regulates many cellular processes, in addition to its role in the regulation of glycogen synthase. GSK-3β is emerged as a promising drug target for various neurological diseases, type-2 diabetes, cancer, and inflammation. Several works have demonstrated that lithium can either inhibit or stimulate growth of normal and cancer cells. Hence, the present study is focused to analyze the underlying mechanisms that dictate the biphasic oncogenic properties of LiCl. In the current study, we have investigated the dose-dependent effects of LiCl on human breast cancer cells (MCF-7) by assessing the consequences on cytotoxicity and protein expressions of signaling molecules crucial for the maintenance of cell survival. The results showed breast cancer cells respond in a diverse manner to LiCl, i.e., at lower concentrations (1, 5, and 10mM), LiCl induces cell survival by inhibiting apoptosis through regulation of GSK-3β, caspase-2, Bax, and cleaved caspase-7 and by activating anti-apoptotic proteins (Akt, β-catenin, Bcl-2, and cyclin D1). In contrast, at high concentrations (50 and 100mM), it induces apoptosis by reversing these effects. Moreover, LiCl also alters the sodium and potassium levels thereby altering the membrane potential of MCF-7 cells. Thus it is inferred that LiCl exerts a dose-dependent biphasic effect on breast cancer cells (MCF-7) by altering the apoptotic/anti-apoptotic balance.

Autophagy modulators sensitize prostate epithelial cancer cell lines to TNF-alpha-dependent apoptosis

TNF-alpha levels in prostate cancer correlate with the extent of disease and are significantly elevated in the metastatic stage. TNF receptor superfamily controls two distinct signalling cascades, leading to opposite effects, i.e. apoptosis and survival; in prostate cancer TNF-alpha-mediated signalling induces cell survival and resistance to therapy. The apoptosis of prostate epithelial cancer cells LNCaP and PC3 was investigated upon treatment with the autophagy inhibitor 3-methyladenine and the autophagy inducer rapamycin, in combination with TNF-alpha. Cells were exposed to these molecules for 18, 24 and 48 h. Autophagy was assessed via LC3 Western blot analysis; propidium iodide and TUNEL stainings followed by flow cytometry or caspase-8 and caspase-3 activation assays were performed to evaluate apoptosis. TNF-alpha-induced apoptosis was potentiated by 3-methyladenine in the androgen-responsive LNCaP cells, whereas no effect was observed in the androgen-insensitive PC3 cells. Interestingly such pro-apoptosis effect in LNCaP cells was associated with reduced c-Flip levels through proteasomal degradation via increased reactive oxygen species production and p38 activation; such c-Flip reduction was reversed in the presence of either the proteasome inhibitor MG132 or the reactive oxygen species scavenger N-acetyl-cysteine. Conversely in PC3 but not in LNCaP cells, rapamycin stimulated TNF-alpha-dependent apoptosis; such effect was associated with reduced c-Flip promoter activity and FoxO3a activation. We conclude that TNF-alpha-induced apoptosis may be potentiated, in prostate cancer epithelial cells, through autophagy modulators. Increased sensitivity to TNF-alpha-dependent apoptosis correlates with reduced c-Flip levels which are consequent to a post-transcriptional and a transcriptional mechanism in LNCaP and PC3 cells respectively.

Induction of Anti-Apoptotic Genes in Cultured Small, Large, and Mixed Ovine Luteal Cells in Response to Interferon-Tau.

Ovine interferon-t (oIFNT) is released from the conceptus into the uterine vein by Day 15 of pregnancy and has endocrine action through inducing IFN-stimulated genes (ISGs) in the corpus luteum (CL). ISG15 is localized to large and small luteal cells based on immunohistochemical staining. Large luteal cells contain prostaglandin F2a (PGF) receptors that stimulate apoptotic signalling and release of oxytocin (OXT) when bound to ligand. Small luteal cells contain OXT receptors, and when activated also induce apoptotic signalling. Infusion of 200 μg of recombinant (r) oIFNT/day into the uterine vein of ewes induces cell survival genes in the CL such as B cell lymphoma extra large (Bcl-XL), protein kinase B (Akt), and X-linked inhibitor of apoptosis (XIAP). Endocrine delivery of 20 μg roIFNT/day into the uterine vein or subcutaneously to the ewes on Day 10 of the estrous cycle also protects the CL against the decline in serum progesterone concentrations caused by injection with PGF on Day 11 of the estrous cycle. Others have described the presence of PGE2 in uterine vein blood and its luteotrophic action on the CL. The present in vitro studies tested the hypothesis that IFNT, rather than PGE2, induces ISG15 and cell survival genes in cultured luteal cells. CLs were collected from adult ewes on Day 10 of the estrous cycle and prepared as mixed (1 x 106/ml) or separated by elutriation into small (2 x 106/ml ) or large (5 x 105/ml) luteal cells. Luteal cells were cultured for 24 h in M199 media supplemented with 10% FBS. The media was replaced with serum-free media and treatments were added to cells. Differences are described as P < 0.05. Culture with 0.1, 1, 10 or 100 ng/ml of roIFNT (108 U/mg) revealed that 1 ng/ml induced ISG15 mRNA concentrations (determined by semi-quantitative RTPCR) in small, large and mixed cells that were in the upper (~80-90% of maximum) linear response to these doses of roIFNT. Cells also were cultured with 10 μM OXT, 3.5 ng/ml PGF and 3.5 ng/ml PGE2, based on effective doses published by others. The roIFNT induced greater BCL-XL, Akt and XIAP mRNA concentrations in small, mixed and large cell cultures when compared to controls. PGE2, PGF and OXT had no effect on ISG15 mRNA concentrations. PGF caused a slight induction of Bcl-XL in large luteal cells and a slight reduction of XIAP mRNA concentrations in mixed luteal cells, but otherwise had no effect. OXT had no effect on Bcl-XL or Akt, but slightly upregulated XIAP mRNA concentrations in small luteal cells. PGE2 had no effect on XIAP, but slightly decreased Bcl-XL and Akt mRNA concentrations in small and large cells. It is concluded that ISG15, Bcl-XL, Akt, and XIAP mRNAs are up regulated within 24h in response to roIFNT treatment of isolated small, large and mixed luteal cells, and that this induction is independent of the actions of PGE2, OXT and PGF. These results are similar to the results obtained in previous in vivo studies using osmotic infusion of roIFNT into the uterine vein of ewes. Endocrine action of IFNT might entail up regulation of ISGs as well as cell survival genes to assist with providing resistance of the CL to PGF, but also in longer-term resilience in context of continued production of progesterone. USDA-NIFA-AFRI 2011–67015–20067. Dr. Sereno is on sabbatical leave from Embrapa Cerrados, Planaltina, DF, Brazil.

Pinosylvin Induces Cell Survival, Migration and Anti‐Adhesiveness of Endothelial Cells via Nitric Oxide Production

Pinosylvin is a phenolic compound mainly found in the Pinus species. To determine the vascular functions of pinosylvin, we first examined both proliferation and apoptosis of bovine aortic endothelial cells (BAECs) in the presence of pinosylvin. When BAECs were treated with pinosylvin, etoposide- or starvation-induced apoptosis was shown to be significantly reduced. The anti-apoptotic effect of pinosylvin was mediated by inhibition of caspase-3. Moreover, pinosylvin was shown to activate endothelial nitric oxide synthetase (eNOS). At 1 pM, pinosylvin appeared to have a cell-proliferative effect in the endothelial cell. The pinosylvin-induced cell proliferation was declined by treatment with L-NAME, an eNOS inhibitor. Then, we found that pinosylvin had a stimulatory effect on cell migration and tube formation. These stimulatory effects suggest that pinosylvin is likely to act as a pro-angiogenic factor. Yet another effect of pinosylvin was inhibition of lipopolysaccharide-induced THP-1 cell adhesion to endothelial cells. Altogether, we propose that pinosylvin may be utilized as a phytotherapic agent for the prevention of cardiovascular inflammatory diseases.

Abstract 3868: ROR1 is expressed in human breast cancer and associated with enhanced tumor-cell growth

Abstract The receptor-tyrosine-kinase-like orphan receptor 1 (ROR1) was identified by a polymerase chain reaction (PCR)-based search for tyrosine kinases similar to the tropomyocin receptor kinase (Trk) neurotropic receptors. ROR1 and a related protein, ROR2, were identified as orphan receptors with an extracellular Frizzled-like, cysteine-rich domain, an extracellular, membrane-proximal kringle domain, and an intracellular tyrosine-kinase-like domain. Both ROR proteins are primarily expressed during embryogenesis. In prior studies, we and others found that ROR1 was expressed by leukemia cells and some cancer cell lines, and was involved in cell survival. However, it was not known whether breast tumor cells expressed ROR1 or whether its expression had functional and clinical significance. In the present study we used a high-affinity mAb specific for ROR1 (named 4A5) to examine human breast cancers and investigate its functional role for tumor growth. We examined fresh-frozen tumor biopsy specimens or tissue microarrays of neoplastic and normal adult tissues for ROR1. The neoplastic cells of high proportions of human breast cancers (70%) expressed ROR1, which was not detected on non-neoplastic adult breast tissues. We interrogated available DNA microarray datasets on primary human breast cancers and cancer cell lines, and fount that breast cancer cell lines or primary breast cancers that expressed high-levels of ROR1 were more likely to lack expression of estrogen or progesterone receptors or HER2/Neu. Conceivably, tumors that are poorly differentiated are more likely to express ROR1. Patients who had primary breast cancers that expressed higher levels of ROR1 had a significantly shorter median survival than did patients with primary breast cancers that had low-to-negligible expression of ROR1. We silenced ROR1 expression in breast cancer cell lines to evaluate its function on tumors. When silenced for ROR1 for MDA-MB-231 cells that expressed ROR1, MDA-MB-231 cells were more sensitive to spontaneous apoptosis and had an impaired cell growth in vitro and in vivo. On the other hand, MCF-7 cells that were transduced to express ROR1 had more aggressive growth characteristics than did control MCF-7 cells. We investigated the mechanism by ROR1 induced cell survival and found that ROR1 could interact with casein kinase 1 epsilon (CK1α) to activate phosphoinositide 3-kinase-mediated AKT phosphorylation and cAMP-response-element-binding protein (CREB), which in turn induce expression of genes (CCNB1, BCL2, and CCND1) that can enhance resistance to apoptosis and/or promote tumor growth. Moreover, Wnt5a, a ligand of ROR1, could induce ROR1-dependent signaling and enhance cell growth. This study demonstrates that ROR1 is expressed in human breast cancers and has biological and clinical significance, indicating that it may be a potential target for breast cancer therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3868. doi:1538-7445.AM2012-3868

N-cadherin mediates neuronal cell survival through Bim down-regulation.

N-cadherin is a major adhesion molecule involved in the development and plasticity of the nervous system. N-cadherin-mediated cell adhesion regulates neuroepithelial cell polarity, neuronal precursor migration, growth cone migration and synaptic plasticity. In vitro, it has been involved in signaling events regulating processes such as cell mobility, proliferation and differentiation. N-cadherin has also been implicated in adhesion-dependent protection against apoptosis in non-neuronal cells. In this study, we investigated if the engagement of N-cadherin participates to the control of neuronal cells survival/death balance. We observed that plating either primary mouse spinal cord neurons or primary rat hippocampal neurons on N-cadherin recombinant substrate greatly enhances their survival compared to non-specific adhesion on poly-L-lysine. We show that N-cadherin engagement, in the absence of other survival factors (cell-matrix interactions and serum), protects GT1-7 neuronal cells against apoptosis. Using this cell line, we then searched for the signaling pathways involved in the survival effect of N-cadherin engagement. The PI3-kinase/Akt survival pathway and its downstream effector Bad are not involved, as no phosphorylation of Akt or Bad proteins in response to N-cadherin engagement was observed. In contrast, N-cadherin engagement activated the Erk1/2 MAP kinase pathway. Moreover, N-cadherin ligation mediated a 2-fold decrease in the level of the pro-apoptotic protein Bim-EL whereas the level of the anti-apoptotic protein Bcl-2 was unchanged. Inhibition of Mek1/2 kinases with U0126, and the resulting inhibition of Erk1/2 phosphorylation, induced the increase of both the level of Bim-EL and apoptosis of cells seeded on the N-cadherin substrate, suggesting that Erk phosphorylation is necessary for cell survival. Finally, the overexpression of a phosphorylation defective form of Bim-EL prevented N-cadherin-engagement induced cell survival. In conclusion, our results show that N-cadherin engagement mediates neuronal cell survival by enhancing the MAP kinase pathway and down-regulating the pro-apoptotic protein Bim-EL.

Upregulation of CD9 in ovarian cancer is related to the induction of TNF-α gene expression and constitutive NF-κB activation

Ovarian cancer is a gynecological cancer with a high death rate. We utilized global gene expression profiles of ovarian carcinomas obtained by complementary DNA (cDNA) microarray to identify ovarian cancer-specific proteins. CD9 was upregulated in ovarian carcinomas, and overexpression of the CD9 protein was detected in ovarian carcinomas by immunohistochemistry. CD9 was also overexpressed in several cancer cell lines, including ovarian cancer cells. In order to elucidate the biological significance of highly expressed CD9 in cancer cells, functional studies of CD9 were performed by ectopic expression, knockdown of CD9 using small interfering RNA (siRNA) and blockage of CD9 activity using the CD9-specific monoclonal antibody ALB6. Ectopic CD9 induced cell survival. In order to identify signaling pathways related to CD9, the gene expressions of CD9/SKOV3 cells were analyzed by cDNA microarray. Among the many upregulated genes, tumor necrosis factor (TNF)-α was induced in CD9/SKOV3 cells. The effect of overexpressed CD9 on the downstream signaling events of TNF-α was further investigated. In CD9/SKOV3 cells, the nuclear factor-kappaB (NF-κB)-signaling pathway was constitutively activated. Knockdown of CD9 by siRNA and blockage of CD9 activity by ALB6 in ovarian cancer cells demonstrated that constitutive activation of NF-κB is CD9 dependent and that CD9 is involved in anti-apoptosis. A CD9 functional study was performed in an ovarian cancer-xenograft mouse by injecting ALB6 into the peritoneum. ALB6 resulted in reduced tumor weight compared with that of control IgG(1). Collectively, these results demonstrate that CD9 functions as an oncogene and represents a target for the development of cancer-specific therapeutics.

Endogenous Signaling by Omega-3 Docosahexaenoic Acid-derived Mediators Sustains Homeostatic Synaptic and Circuitry Integrity

The harmony and function of the complex brain circuits and synapses are sustained mainly by excitatory and inhibitory neurotransmission, neurotrophins, gene regulation, and factors, many of which are incompletely understood. A common feature of brain circuit components, such as dendrites, synaptic membranes, and other membranes of the nervous system, is that they are richly endowed in docosahexaenoic acid (DHA), the main member of the omega-3 essential fatty acid family. DHA is avidly retained and concentrated in the nervous system and known to play a role in neuroprotection, memory, and vision. Only recently has it become apparent why the surprisingly rapid increases in free (unesterified) DHA pool size take place at the onset of seizures or brain injury. This phenomenon began to be clarified by the discovery of neuroprotectin D1 (NPD1), the first-uncovered bioactive docosanoid formed from free DHA through 15-lipoxygenase-1 (15-LOX-1). NPD1 synthesis includes, as agonists, oxidative stress and neurotrophins. The evolving concept is that DHA-derived docosanoids set in motion endogenous signaling to sustain homeostatic synaptic and circuit integrity. NPD1 is anti-inflammatory, displays inflammatory resolving activities, and induces cell survival, which is in contrast to the pro-inflammatory actions of the many of omega-6 fatty acid family members. We highlight here studies relevant to the ability of DHA to sustain neuronal function and protect synapses and circuits in the context of DHA signalolipidomics. DHA signalolipidomics comprises the integration of the cellular/tissue mechanism of DHA uptake, its distribution among cellular compartments, the organization and function of membrane domains containing DHA phospholipids, and the precise cellular and molecular events revealed by the uncovering of signaling pathways regulated by docosanoids endowed with prohomeostatic and cell survival bioactivity. Therefore, this approach offers emerging targets for prevention, pharmaceutical intervention, and clinical translation involving DHA-mediated signaling.

Enhanced Phosphoinositide 3-Kinase δ Activity Is a Frequent Event in Systemic Lupus Erythematosus That Confers Resistance to Activation-Induced T Cell Death

Systemic lupus erythematosus (SLE) is a human chronic inflammatory disease caused by the action of autoreactive T and B cells. Class I phosphoinositide-3-kinases (PI3K) are enzymes that trigger formation of 3-poly-phosphoinositides that induce cell survival. Enhanced PI3K activation is a frequent event in human cancer. Nonetheless, in a genetic model with enhanced activation of class I(A) PI3K in T cells, mice show a greater tumor index but die of a lupus-like disease. In this study, we studied the potential PI3K involvement in human SLE. The PI3K pathway was frequently activated in SLE patient PBMC and T cells (∼70% of cases), more markedly in active disease phases. We examined the mechanism for PI3K pathway activation and found enhanced activation of PI3Kδ in SLE peripheral blood T cells. The magnitude of PI3K pathway activation in patients paralleled activated/memory T cell accumulation. We examined potential tolerance mechanisms affected by increased PI3K activity; SLE patients showed reduced activation-induced cell death of activated/memory T cells. Moreover, the defective activation-induced cell death in SLE T cells was corrected after reduction of PI3Kδ activity, suggesting that PI3Kδ contributes to induction of enhanced SLE memory T cell survival. These observations point to PI3Kδ as a target of clinical interest for SLE.

Docosahexaenoic Acid Signalolipidomics in Nutrition: Significance in Aging, Neuroinflammation, Macular Degeneration, Alzheimer's, and Other Neurodegenerative Diseases

Essential polyunsaturated fatty acids (PUFAs) are critical nutritional lipids that must be obtained from the diet to sustain homeostasis. Omega-3 and -6 PUFAs are key components of biomembranes and play important roles in cell integrity, development, maintenance, and function. The essential omega-3 fatty acid family member docosahexaenoic acid (DHA) is avidly retained and uniquely concentrated in the nervous system, particularly in photoreceptors and synaptic membranes. DHA plays a key role in vision, neuroprotection, successful aging, memory, and other functions. In addition, DHA displays anti-inflammatory and inflammatory resolving properties in contrast to the proinflammatory actions of several members of the omega-6 PUFAs family. This review discusses DHA signalolipidomics, comprising the cellular/tissue organization of DHA uptake, its distribution among cellular compartments, the organization and function of membrane domains rich in DHA-containing phospholipids, and the cellular and molecular events revealed by the uncovering of signaling pathways regulated by DHA and docosanoids, the DHA-derived bioactive lipids, which include neuroprotectin D1 (NPD1), a novel DHA-derived stereoselective mediator. NPD1 synthesis agonists include neurotrophins and oxidative stress; NPD1 elicits potent anti-inflammatory actions and prohomeostatic bioactivity, is anti-angiogenic, promotes corneal nerve regeneration, and induces cell survival. In the context of DHA signalolipidomics, this review highlights aging and the evolving studies on the significance of DHA in Alzheimer's disease, macular degeneration, Parkinson's disease, and other brain disorders. DHA signalolipidomics in the nervous system offers emerging targets for pharmaceutical intervention and clinical translation.

Pigment epithelium-derived factor inhibits advanced glycation end-products-induced cytotoxicity in retinal pericytes

Aim This study investigated the effects of pigment epithelium-derived factor (PEDF) on advanced glycation end-product (AGE)-induced cytotoxicity in porcine retinal pericytes and the signalling mechanism involved. Methods Retinal pericytes were isolated from porcine eyes and characterized by immunocytochemistry. The effect of AGEs and PEDF on cell proliferation was determined by bromodeoxyuridine (BrdU) assay. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity was analyzed by luminescence assay. Reactive oxygen species (ROS), nitric oxide (NO), superoxide dismutase (SOD) and glutathione peroxidase (GSH) were determined by biochemical assays. Induction of apoptosis was determined by caspase-3 colorimetric assay and DNA fragmentation analysis. Src activity was assessed by transient transfection analysis, and the status of Src phosphorylation at Y419 was analyzed by a competitive ELISA method. Results AGEs significantly increased intracellular ROS generation in pericytes via NADPH oxidase and induced cell death via caspase-3 enzyme activation, whereas PEDF increased cell proliferation in a dose-dependent manner. In addition, PEDF inhibited AGE-induced ROS generation by increasing levels of SOD and GSH, and also blocked the activation of caspase-3. Furthermore, PEDF induced cell survival via the Src pathway by Src phosphorylation at Y419, as evidenced by a pharmacological inhibitor and Src mutants. Conclusion These results suggest that PEDF abrogates AGE-induced oxidative stress and apoptosis in retinal pericytes via the Src pathway, thereby suggesting that PEDF is an effective therapeutic agent for the treatment of loss of pericytes in early diabetic retinopathy.