Role of neuronal NADPH oxidase 1 in the peri-infarct regions after stroke

The molecular mechanism underlying the selective vulnerability of neurons to oxidative damage caused by ischemia-reperfusion (I/R) injury remains unknown. We sought to determine the role of NADPH oxidase 1 (Nox1) in cerebral I/R-induced brain injury and survival of newborn cells in the ischemic injured region. Male Wistar rats were subjected to 90 min middle cerebral artery occlusion (MCAO) followed by reperfusion. After reperfusion, infarction size, level of superoxide and 8-hydroxy-2'-deoxyguanosine (8-oxo-2dG), and Nox1 immunoreactivity were determined. RNAi-mediated knockdown of Nox1 was used to investigate the role of Nox1 in I/R-induced oxidative damage, neuronal death, motor function recovery, and ischemic neurogenesis. After I/R, Nox1 expression and 8-oxo-2dG immunoreactivity was increased in cortical neurons of the peri-infarct regions. Both infarction size and neuronal death in I/R injury were significantly reduced by adeno-associated virus (AAV)-mediated transduction of Nox1 short hairpin RNA (shRNA). AAV-mediated Nox1 knockdown enhanced functional recovery after MCAO. The level of survival and differentiation of newborn cells in the peri-infarct regions were increased by Nox1 inhibition. Our data suggest that Nox-1 may be responsible for oxidative damage to DNA, subsequent cortical neuronal degeneration, functional recovery, and regulation of ischemic neurogenesis in the peri-infarct regions after stroke.

Matrix metalloproteinase-3 causes dopaminergic neuronal death through Nox1-regenerated oxidative stress

In the present study we investigated the interplay between matrix metalloproteinase 3 (MMP3) and NADPH oxidase 1 (Nox1) in the process of dopamine (DA) neuronal death. We found that MMP3 activation causes the induction of Nox1 via mitochondrial reactive oxygen species (ROS) production and subsequently Rac1 activation, eventually leading to Nox1-derived superoxide generation in a rat DA neuronal N27 cells exposed to 6-OHDA. While a MMP3 inhibitor, NNGH, largely attenuated mitochondrial ROS and subsequent Nox1 induction, both apocynin, a putative Nox inhibitor and GKT137831, a Nox1 selective inhibitor failed to reduce 6-OHDA-induced mitochondrial ROS. However, both inhibitors for MMP3 and Nox1 similarly attenuated 6-OHDA-induced N27 cell death. RNAi-mediated selective inhibition of MMP3 or Nox1 showed that knockdown of either MMP3 or Nox1 significantly reduced 6-OHDA-induced ROS generation in N27 cells. While 6-OHDA-induced Nox1 was abolished by MMP3 knockdown, Nox1 knockdown did not alter MMP3 expression. Direct overexpression of autoactivated MMP3 (actMMP3) in N27 cells or in rat substantia nigra (SN) increased expression of Nox1. Selective knockdown of Nox1 in the SN achieved by adeno-associated virus-mediated overexpression of Nox1-specific shRNA largely attenuated the actMMP3-mediated dopaminergic neuronal loss. Furthermore, Nox1 expression was significantly attenuated in Mmp3 null mice treated with N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Together we established novel molecular mechanisms underlying oxidative stress-mediated dopaminergic neuronal death in which MMP3 activation is a key upstream event that leads to mitochondrial ROS, Nox1 induction and eventual dopaminergic neuronal death. Our findings may lead to the development of novel therapeutic approach.

DJ-1 regulates the expression of renal (pro)renin receptor via reactive oxygen species-mediated epigenetic modification

BACKGROUND

DJ-1 protein plays multifunctional roles including transcriptional regulation and scavenging oxidative stress; thus, it may be associated with the development of renal disorders. We investigated whether DJ-1 protein regulates the expression of (pro)renin receptor (PRR), a newly identified member of renin-angiotensin system.

METHODS

The levels of mRNA and protein were determined by real-time PCR and western blot, respectively. H2O2 production was tested by using fluorescence probe. Histone modification was determined by chromatin immunoprecipitation.

RESULTS

The expression of PRR was significantly higher in the kidney from DJ-1 knockout mice (DJ-1-/-) compared with wild-type mice (DJ-1+/+). Histone deacetylase 1 recruitment at the PRR promoter was lower, and histone H3 acetylation and RNA polymerase II recruitment were higher in DJ-1-/- than in DJ-1+/+. Knockdown or inhibition of histone deacetylase 1 restored PRR expression in mesangial cells from DJ-1+/+. H2O2 production was greater in DJ-1-/- cells compared with DJ-1+/+ cells. These changes in PRR expression and epigenetic modification in DJ-1-/- cells were induced by H2O2 treatment and reversed completely by addition of an antioxidant reagent. Prorenin-stimulated ERK1/2 phosphorylation was greater in DJ-1-/- than in DJ-1+/+ cells and this was inhibited by a PRR-inhibitory peptide, and by AT1 and AT2 receptor inhibitors. The expression of renal fibrotic genes was higher in DJ-1-/- than in DJ-1+/+ cells and decreased in PRR-knockdown DJ-1-/- cells.

CONCLUSIONS

We conclude that DJ-1 protein regulates the expression of renal PRR through H2O2-mediated epigenetic modification.

GENERAL SIGNIFICANCE

We suggest that renal DJ-1 protein may be an important molecule in the acceleration of renal pathogenesis through PRR regulation.

Abstract 5263: Identification of a lipid raft protein that is required for H-Ras activation and breast cancer aggressiveness

In an attempt to identify biomarkers and/or therapeutic targets for malignant breast cancer, the present study showed a comparative proteome profiling of invasive MCF10A human breast epithelial cells engineered to express active H-Ras and non-invasive cells expressing active N-Ras. Here, we identified a lipid raft protein DS-20, a crucial regulator of H-Ras activation, as a potential marker for invasive breast cancer. DS-20 (amino acid residues 1-38) interacted with H-Ras (residues 166-189) in lipid rafts and their interaction was important for H-Ras activation. DS-20 knockdown inhibited H-Ras activation and invasion in Hs578T triple-negative breast cancer cells (TNBC) and T24 bladder carcinoma cells in which H-Ras is endogenously activated, suggesting a crucial role of DS-20 in the invasive program which relies on the activation of H-Ras. We further showed that DS-20 was required for epidermal growth factor-induced H-Ras activation, but not that of N-Ras, in MDA-MB-231 TNBC cells. Intravasation of MDA-MB-231 cells treated with shRNA DS-20 in the chick chorioallantoic membrane model was markedly reduced, indicating that DS-20 is required for an invasive capacity in vivo. In a xenograft mice tumor model, DS-20 was essential for in vivo tumor aggressiveness of Hs578T cells, suggesting DS-20 as a potential target for the treatment of breast cancer. Using human breast cancer samples, we provide clinical evidence for the tumorigenic potential of DS-20 and its association with H-Ras. Taken together, our findings provide a new insight into the molecular basis of Ras isoform-specific interplay with plasma membrane leading to cell invasion.

Citation Format: Hae-Young Yong, Eun-Sook Kim, Minsoo Koh, Hwajin Son, You Rim Jeon, Jin-Sun Hwang, Myeong-Ok Kim, Yujin Cha, Wahn Soo Choi, Dong-Young Noh, Kyung-Min Lee, Ki-Bum Kim, Jae-Seon Lee, Hyung Joon Kim, Hong-Hee Kim, Eun Joo Kim, So Yeon Park, Hyeong-Reh Choi Kim, Aree Moon. Identification of a lipid raft protein that is required for H-Ras activation and breast cancer aggressiveness. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5263. doi:10.1158/1538-7445.AM2014-5263

Tonicity-responsive enhancer binding protein haplodeficiency attenuates seizure severity and NF-κB-mediated neuroinflammation in kainic acid-induced seizures

Kainic acid (KA)-induced seizures followed by neuronal death are associated with neuroinflammation and blood-brain barrier (BBB) leakage. Tonicity-responsive enhancer binding protein (TonEBP) is known as a transcriptional factor activating osmoprotective genes, and in brain, it is expressed in neuronal nuclei. Thus dysregulation of TonEBP may be involved in the pathology of KA-induced seizures. Here we used TonEBP heterozygote (+/-) mice to study the roles of TonEBP. Electroencephalographic study showed that TonEBP (+/-) mice reduced seizure frequency and severity compared with wild type during KA-induced status epilepticus. Immunohistochemistry and western blotting analysis showed that KA-induced neuroinflammation and BBB leakage were dramatically reduced in TonEBP (+/-) mice. Similarly, TonEBP-specific siRNA reduced glutamate-induced death in HT22 hippocampal neuronal cells. TonEBP haplodeficiency prevented KA-induced nuclear translocation of NF-κB p65 and attenuated inflammation. Our findings identify TonEBP as a critical regulator of neuroinflammation and BBB leakage in KA-induced seizures, which suggests TonEBP as a good therapeutic target.

Increased NFAT5 expression stimulates transcription of Hsp70 in preeclamptic placentas

OBJECTIVE

We investigated the expression of heat shock protein 70 (Hsp70), nuclear factor of activated T cells 5 (NFAT5), and hypoxia-induced factor-1α (HIF-1α) in the placentas of normal and preeclamptic pregnancies and in human placental hypoxia models in vitro to examine the regulatory mechanisms of placental Hsp70 expression.

METHODS

The expression levels of HIF-1α, NFAT5, and Hsp70 were examined in placental samples from 10 females with preeclampsia and 10 normotensive control patients and in human choriocarcinoma trophoblast cells treated with 1 mM CoCl2 by western blotting. Using models of placental hypoxia, pharmacological inhibition of HIF-1α with chetomin and shRNA knockdown and overexpression of NFAT5 were performed to investigate the roles of HIF-1α and NFAT5 in induction of Hsp70 by placental hypoxia.

RESULTS

The levels of HIF-1α, NFAT5, and Hsp70 expression were significantly higher in the preeclamptic compared to normal placentas. In the placental hypoxia models, the expression of HIF-1α, NFAT5, and Hsp70 were significantly higher after 3, 6, and 12 h of 1 mM CoCl2 treatment, respectively. Pharmacological inhibition of HIF-1α suppressed the induction of NFAT5 and Hsp70 at the protein level. shRNA knockdown of NFAT5 suppressed the induction of Hsp70 protein and overexpression of NFAT5 stimulated the induction of Hsp70 mRNA and protein in models of human placental hypoxia in vitro.

CONCLUSION

HIF-1α positively regulates the induction of NFAT5 and Hsp70 by placental hypoxia and NFAT5 stimulates transcription of Hsp70 in response to placental hypoxia in models of human placental hypoxia in vitro.

A novel anthracene derivative, MHY412, induces apoptosis in doxorubicin-resistant MCF-7/Adr human breast cancer cells through cell cycle arrest and downregulation of P-glycoprotein expression

New potential chemotherapeutic strategies are required to overcome multidrug resistance (MDR) in cancer. This study investigated the anticancer effect of a novel anthracene derivative MHY412 on doxorubicin-resistant human breast cancer (MCF-7/Adr) cells. We measured cell viability and the expression of apoptosis-related genes; in addition, the antitumor activity of MHY412 was confirmed using an in vivo tumor xenograft model. MHY412 significantly inhibited the proliferation of MCF-7/Adr and MCF-7 cells in a concentration-dependent manner. Notably, the half-maximal inhibitory concentration (IC50) values of MHY412 in MCF-7/Adr (0.15 µM) and MCF-7 (0.26 µM) cells were lower than those of doxorubicin (MCF-7/Adr, 13.6 µM and MCF-7, 1.26 µM) after treatment for 48 h. MHY412 at low concentrations induced S phase arrest, but at high concentrations, the number of MCF-7/Adr cells in the sub-G1 phase significantly increased. MHY412-induced sub-G1 phase arrest was associated with inhibition of cyclin, cyclin-dependent kinase 2 (CDK2) and p21 expression in MCF-7/Adr cells. MHY412 markedly reduced P-glycoprotein (P-gp) expression and increased apoptotic cell death in MCF-7/Adr cells. Cleavage of poly-ADP ribose polymerase, reduced Bcl-2 expression, and increased in cytochrome c release in MCF-7/Adr cells confirmed the above results. In addition, MHY412 markedly inhibited tumor growth in a tumor xenograft model of MCF-7/Adr cells. Our data suggest that MHY412 exerts antitumor effects by selectively modulating the genes related to cell cycle arrest and apoptosis. In particular, MHY412 is a new candidate agent for the treatment of Bcl-2 overexpressed doxorubicin-resistant human breast cancer.

Resveratrol enhances chemosensitivity of doxorubicin in multidrug-resistant human breast cancer cells via increased cellular influx of doxorubicin

BACKGROUND

Multidrug resistance is a major problem in the treatment of breast cancer, and a number of studies have attempted to find an efficient strategy with which to overcome it. In this study, we investigate the synergistic anticancer effects of resveratrol (RSV) and doxorubicin (Dox) against human breast cancer cell lines.

METHODS

The synergistic effects of RSV on chemosensitivity were examined in Dox-resistant breast cancer (MCF-7/adr) and MDA-MB-231 cells. In vivo experiments were performed using a nude mouse xenograft model to investigate the combined sensitization effect of RSV and Dox.

RESULTS AND CONCLUSION

RSV markedly enhanced Dox-induced cytotoxicity in MCF-7/adr and MDA-MB-231 cells. Treatment with a combination of RSV and Dox significantly increased the cellular accumulation of Dox by down-regulating the expression levels of ATP-binding cassette (ABC) transporter genes, MDR1, and MRP1. Further in vivo experiments in the xenograft model revealed that treatment with a combination of RSV and Dox significantly inhibited tumor volume by 60%, relative to the control group.

GENERAL SIGNIFICANCE

These results suggest that treatment with a combination of RSV and Dox would be a helpful strategy for increasing the efficacy of Dox by promoting an intracellular accumulation of Dox and decreasing multi-drug resistance in human breast cancer cells.

The scaffold protein prohibitin is required for antigen-stimulated signaling in mast cells

The protein prohibitin (PHB) is implicated in diverse cellular processes, including cell signaling, transcriptional control, and mitochondrial function. We found that PHB was abundant in the intracellular granules of mast cells, which are critical for allergic responses to antigens. Thus, we investigated whether PHB played a role in signaling mediated by the high-affinity receptor for antigen-bound immunoglobulin E (IgE), FcεRI. PHB-specific small interfering RNAs (siRNAs) inhibited antigen-mediated signaling, degranulation, and cytokine secretion by mast cells in vitro. Knockdown of PHB inhibited the antigen-dependent association of the tyrosine kinase Syk with FcεRI and inhibited the activation of Syk. Fractionation studies revealed that PHB translocated from intracellular granules to plasma membrane lipid rafts in response to antigen, and knockdown of PHB suppressed the movement of FcεRIγ and Syk into lipid rafts. Tyrosine phosphorylation of PHB by Lyn was observed early after exposure to antigen, and point mutations in PHB indicated that Tyr(114) and Tyr(259) were required for the recruitment of Syk to FcεRIγ and mast cell activation. In mice, PHB-specific siRNAs inhibited antigen-initiated mast cell degranulation, passive cutaneous anaphylaxis, and passive systemic anaphylaxis. Together, these results suggest that PHB is essential for FcεRI-mediated mast cell activation and allergic responses in vivo, raising the possibility that PHB might serve as a therapeutic target for the treatment of allergic diseases.

Topotactic phase transformation of the brownmillerite SrCoO2.5 to the perovskite SrCoO3- δ

Pulsed laser epitaxy of brownmillerite SrCoO2.5 thin films and their phase transformation to the perovskite SrCoO3-δ are investigated. While the direct growth of the fully oxidized perovskite films is found to be an arduous task, filling some of oxygen vacancies into SrCoO2.5 by topotactic oxidation accompanies systematic evolution of electronic, magnetic, and thermoelectric properties, useful for many information and energy technologies.

DJ-1 regulates mast cell activation and IgE-mediated allergic responses

BACKGROUND

DJ-1 is an antioxidant protein known to reduce levels of reactive oxygen species (ROS), but its presence or function in mast cells and allergic diseases is unknown.

OBJECTIVES

We sought to determine the role and mechanism of DJ-1 in allergic responses in vitro and in vivo.

METHODS

ROS and DJ-1 levels in serum or culture medium were measured with ELISA kits. The role of DJ-1 was evaluated in mast cell cultures and passive cutaneous anaphylaxis in normal or DJ-1 knockout (KO) mice. The mechanism of DJ-1 action was examined by using immunoblotting, immunoprecipitation, RT-PCR, and other molecular biological approaches.

RESULTS

Patients with atopic dermatitis had increased levels of ROS and diminished levels of DJ-1. DJ-1 KO mice exhibited enhanced passive cutaneous anaphylaxis and augmented ROS levels in sera and bone marrow-derived mast cells (BMMCs). Furthermore, antigen-induced degranulation and production of TNF-α and IL-4 were significantly amplified in DJ-1 KO and anti-DJ-1 small interfering RNA-transfected BMMCs compared with that seen in wild-type (WT) BMMCs. Studies with these cells and BMMCs transfected with small interfering RNAs against the phosphatases Src homology domain 2-containing protein tyrosine phosphatase (SHP) 1 and SHP-2 revealed that the DJ-1 KO phenotype could be attributed to suppression of SHP-1 activity and enhancement of SHP-2 activity, leading to strengthened signaling through linker for activation of T cells, phospholipase Cγ, and mitogen-activated protein kinases.

CONCLUSIONS

A deficiency or constitutive activation of DJ-1 can have implications in mast cell-driven allergic diseases, such as asthma and anaphylaxis.

Morus bombycis extract suppresses mast cell activation and IgE-mediated allergic reaction in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Morus bombycis Koidzumi (MB) is widely distributed throughout Korea, where it is used as a traditional folk remedy for the treatment of allergic diseases including asthma. However, the pharmacological effect and the mechanistic study of MB have not been investigated. We aimed to investigate the anti-allergic activity of MB in vitro and in vivo and the mechanism of its action on mast cells.

MATERIALS AND METHODS

The anti-allergic activity of MB extract (MBE) was assessed using passive cutaneous anaphylaxis (PCA) in mice and mouse bone marrow-derived mast cells (BMMCs) in vitro. The effects of MBE on mast cell activation were evaluated by using the β-hexosaminidase release assay, reverse transcriptase-polymerase chain reaction, enzyme-linked immunosorbent assay, and western blotting analysis.

RESULTS

MBE reversibly inhibited degranulation and generation of cytokines (TNF-α and IL-4) in antigen-stimulated mast cells. With regard to its mechanism of action, MBE inhibited the activation of Lyn and Syk, which have essential roles in degranulation and the production of various inflammatory cytokines. MBE also inhibited the activating phosphorylation of mitogen-activated protein (MAP) kinases, Erk1/2, p38, JNK, and Akt. In agreement with its in vitro effect, MBE significantly inhibited mast cell-mediated PCA reactions in IgE-sensitized mice.

CONCLUSIONS

The present results strongly suggest that MBE exerts an anti-allergic effect, both in vitro and in vivo by inhibiting the Lyn and Syk pathways in mast cells. Therefore, MBE may be useful for the treatment of allergic diseases, including atopic dermatitis and allergic asthma.

A novel histone deacetylase (HDAC) inhibitor MHY219 induces apoptosis via up-regulation of androgen receptor expression in human prostate cancer cells

Histone deacetylase (HDAC) inhibitors are a new class of anticancer agents that act by inhibiting cancer cell proliferation and inducing apoptosis in various cancer cell lines. To investigate the anticancer effect of a novel histone deacetylase (HDAC) inhibitor MHY219, its efficacy was compared to that of suberoylanilide hydroxamic acid (SAHA) in human prostate cancer cells. The anticancer effects of MHY219 on cell viability, HDAC enzyme activity, cell cycle regulation, apoptosis and other biological assays were performed. MHY219 was shown to enhance the cytotoxicity on DU145 cells (IC₅₀, 0.36 μM) when compared with LNCaP (IC₅₀, 0.97 μM) and PC3 cells (IC₅₀, 5.12 μM). MHY219 showed a potent inhibition of total HDAC activity when compared with SAHA. MHY219 increased histone H3 hyperacetylation and reduced the expression of class I HDACs (1, 2 and 3) in prostate cancer cells. MHY219 effectively increased the sub-G1 fraction of cells through p21 and p27 dependent pathways in DU145 cells. MHY219 significantly induced a G2/M phase arrest in DU145 and PC3 cells and arrested the cell cycle at G0/G1 phase in LNCaP cells. Furthermore, MHY219 effectively increased apoptosis in DU145 and LNCaP cells, but not PC3 cells, according to Annexin V/PI staining and Western blot analysis. These results indicate that MHY219 is a potent HDAC inhibitor that targets regulating multiple aspects of cancer cell death and might have preclinical value in human prostate cancer chemotherapy, warranting further investigation.

DJ-1/park7 protects against neointimal formation via the inhibition of vascular smooth muscle cell growth

AIMS

DJ-1/park7 is a ubiquitously expressed multifunctional protein that plays essential roles in a variety of cells. However, its function in the vascular system has not been determined. We investigated the protective roles of DJ-1/park7 in vascular disorders, especially in neointimal hyperplasia.

METHODS AND RESULTS

DJ-1/park7 was strongly expressed in the neointimal layer, in which its oxidized form was predominant. Treatment of vascular smooth muscle cells (VSMCs) from the mouse aorta with H(2)O(2) increased the oxidation of DJ-1/park7 visualized on two-dimensional electrophoresis gels. The growth of VSMCs in FBS-containing media and the release of H(2)O(2) were significantly increased in DJ-1/park7(-/-) knockout mice compared with DJ-1/park7(+/+) wild-type mice. The expression of cyclin D1 and the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 were greater in VSMCs from the DJ-1/park7(-/-) aorta than from the DJ-1/park7(+/+) aorta. Both of these measures were inhibited by treatment with an ERK1/2 inhibitor or antioxidants and in DJ-1/park7-overexpressing cells. VSMC proliferation, cyclin D1 expression, and ERK1/2 phosphorylation in response to platelet-derived growth factor-BB were upregulated in DJ-1/park7(-/-) compared with DJ-1/park7(+/+) mice. VSMCs of DJ-1/park7(-/-) mice exhibited higher levels of sprout outgrowth of aortic strips and neointimal plaque formation elicited by carotid artery ligation compared with those of DJ-1/park7(+/+) mice.

CONCLUSION

These results indicate that DJ-1/park7 is involved in the growth of VSMCs, thereby inhibiting neointimal hyperplasia, and suggest that it might play protective roles in vascular remodelling.

Reduction of experimental diabetic vascular leakage and pericyte apoptosis in mice by delivery of αA-crystallin with a recombinant adenovirus

AIMS/HYPOTHESIS

The study aimed to evaluate the efficacy of recombinant adenovirus expressing αA-crystallin (Ad-αAc-Gfp) in reducing pericyte loss within retinal vasculature in early diabetes.

METHODS

Diabetes was induced by streptozotocin injection into C57BL/6 mice. Ad-αAc-Gfp was delivered by intravitreous injection to the right eyes of mice 2 weeks before induction of diabetes. Vascular leakage was determined by fluorescent angiography, Evans Blue leakage assay and leucocyte adhesion test. Production of αA-crystallin was analysed by immunoblotting and double immunostaining and pericyte loss was analysed by pericyte count.

RESULTS

Vessel leakage and pericyte loss were observed in the streptozotocin-induced diabetic retina. Decreased abundance of αA-crystallin in retinas 2 and 6 months after the induction of diabetes was confirmed by two-dimensional electrophoretic analysis, immunoblotting and RT-PCR. Double immunofluorescence staining for αA-crystallin and NG2 chondroitin sulphate proteoglycan revealed that αA-crystallin was predominantly produced in the retinal pericyte and that the number of αA-crystallin-producing pericytes decreased in the diabetic retina. Retinal infection with Ad-αAc-Gfp led to decreased pericyte loss and vascular leakage compared with control.

CONCLUSIONS/INTERPRETATION

Intravitreal delivery of Ad-αAc-Gfp protects against vascular leakage in the streptozotocin-induced model of diabetes. This effect is associated with the inhibition of diabetic retinal pericyte loss in early diabetes, suggesting that αA-crystallin has a role in preventing the pathogenesis of early diabetic retinopathy.

Sirtinol, a class III HDAC inhibitor, induces apoptotic and autophagic cell death in MCF-7 human breast cancer cells

Sirtuins (SIRTs), NAD+-dependent class III histone deacetylases (HDACs), play an important role in the regulation of cell division, survival and senescence. Although a number of effective SIRT inhibitors have been developed, little is known about the specific mechanisms of their anticancer activity. In this study, we investigated the anticancer effects of sirtinol, a SIRT inhibitor, on MCF-7 human breast cancer cells. Apoptotic and autophagic cell death were measured. Sirtinol significantly inhibited the proliferation of MCF-7 cells in a concentration-dependent manner. The IC50 values of sirtinol were 48.6 µM (24 h) and 43.5 µM (48 h) in MCF-7 cells. As expected, sirtinol significantly increased the acetylation of p53, which has been reported to be a target of SIRT1/2. Flow cyto-metry analysis revealed that sirtinol significantly increased the G1 phase of the cell cycle. The upregulation of Bax, downregulation of Bcl-2 and cytochrome c release into the cytoplasm, which are considered as mechanisms of apoptotic cell death, were observed in the MCF-7 cells treated with sirtinol. The annexin V-FITC assay was used to confirm sirtinol-induced apoptotic cell death. Furthermore, the expression of LC3-II, an autophagy-related molecule, was significantly increased in MCF-7 cells after sirtinol treatment. Autophagic cell death was confirmed by acridine orange and monodansylcadaverine (MDC) staining. Of note, pre-treatment with 3-methyladenine (3-MA) increased the sirtinol-induced MCF-7 cell cytotoxicity, which is associated with blocking autophagic cell death and increasing apoptotic cell death. Based on our results, the downregulation of SIRT1/2 expression may play an important role in the regulation of breast cancer cell death; thus, SIRT1/2 may be a novel molecular target for cancer therapy and these findings may provide a molecular basis for targeting SIRT1/2 in future cancer therapy.

Abstract 4165: Identification of flotillin-1 as a regulator of H-Ras activation in lipid raft

Metastatic spread is the major cause of death from breast cancer. We previously showed that H-Ras, but not N-Ras, induces invasive/migratory phenotypes of MCF10A human breast epithelial cells, while both H-Ras and N-Ras induce proliferation/transformation. Here, we identified flotillin-1 as an H-Ras-induced lipid raft protein through comparative proteome profiling of lipid raft proteins. Flotillin-1 interacts with H-Ras in lipid raft at a higher affinity than with N-Ras. Small interfering RNA(siRNA)-mediated flotillin-1 knockdown significantly reduced H-Ras activation and H-Ras-mediated motility/invasion in MCF10A cells engineered to express active H-Ras as well as in Hs578T breast carcinoma and T24 bladder carcinoma cells that express endogenous active mutant of H-Ras. These results suggest a positive signal amplification loop between flotillin-1 and H-Ras for the invasive signaling program. Flotillin-1 was crucial for the activation of the Ras-GRF1 exchange factor and its interaction with H-Ras in lipid rafts. Using a xenograft tumor model, we show that knockdown of flotillin-1 reduces the tumor growth in vivo. Importantly, tissue microarrays of 289 breast cancer patients revealed that flotillin-1 expression in the plasma membrane positively correlates with HER2/neu expression(p<0.001) and high histologic grade(p=0.014). Although infrequent, the membranous flotillin-1 expression is significantly associated with poor disease-free survival of patients(p=0.005), suggesting the clinical importance of predicting the characteristics of a small subpopulation of malignant breast cancer. Taken together, our findings provide new insight into the molecular basis of the Ras isoform-specific signaling mechanism leading to cell invasion that depends on the lipid-based sorting platforms.

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 4165. doi:1538-7445.AM2012-4165

Antiallergic activity of novel isoflavone methyl-glycosides from Cordyceps militaris grown on germinated soybeans in antigen-stimulated mast cells

Isoflavones are known to possess immunomodulating and antiallergic activities. Previously we identified novel isoflavone methyl-glycosides (daidzein 7-O-β-d-glucoside 4″-O-methylate (CDGM), glycitein 7-O-β-D-glucoside 4″-O-methylate (CGLM), genistein 7-O-β-D-glucoside 4″-O-methylate (CGNMI) and genistein 4'-O-β-D-glucoside 4″-O-methylate (CGNMII)) from Cordyceps militaris grown on germinated soybeans (GSC). The biological activity of novel isoflavone methyl-glycosides, however, remains unknown. In this study, CGNMII showed the strongest inhibition of degranulation. Additionally, the release of interleukin (IL)-4 and tumor necrosis factor (TNF)-α was decreased by CGNMII in antigen-stimulated RBL-2H3 cells. To elucidate the antiallergic mechanism of CGNMII, we examined whether it affected levels of signaling molecules responsible for degranulation. The levels of activated Lyn, Syk, PLCγ1 and LAT proteins were reduced in CGNMII treated RBL-2H3 cells. CGNMII also inhibited the activation of AKT and ERK1/2 proteins. These results suggest that CGNMII might be used as a therapeutic agent for allergic diseases.

Comparisons of polybrominated diphenyl ethers levels in paired South Korean cord blood, maternal blood, and breast milk samples

Polybrominated diphenyl ethers (PBDEs), commonly used flame retardants, have been reported as potential endocrine disruptor and neurodevelopmental toxicants, thus giving rise to the public health concern. The goal of this study was to investigate the relationship between umbilical cord blood, maternal blood, and breast milk concentrations of PBDEs in South Korean. We assessed PBDE levels in paired samples of umbilical cord blood, maternal blood, and breast milk. The levels of seven PBDE congeners were measured in 21 paired samples collected from the Cheil Woman's Hospital (Seoul, Korea) in 2008. We also measured thyroid hormones levels in maternal and cord blood to assess the association between PBDEs exposure and thyroid hormone levels. However, there was no correlation between serum thyroxin (T4) and total PBDEs concentrations. The total PBDEs concentrations in the umbilical cord blood, maternal blood, and breast milk were 10.7±5.1 ng g(-1) lipid, 7.7±4.2 ng g(-1) lipid, and 3.0±1.8 ng g(-1) lipid, respectively. The ranges of total PBDE concentrations observed were 2.28-30.94 ng g(-1) lipid in umbilical cord blood, 1.8-17.66 ng g(-1) lipid in maternal blood, and 1.08-8.66 ng g(-1) lipid in breast milk. BDE-47 (45-73% of total PBDEs) was observed to be present dominantly in all samples, followed by BDE-153. A strong correlation was found for major BDE-congeners between breast milk and cord blood or maternal blood and cord blood samples. The measurement of PBDEs concentrations in maternal blood or breast milk may help to determine the concentration of PBDEs in infant.