Supplementary Figure 1 from Glutathione-Conjugate Transport by RLIP76 Is Required for Clathrin-Dependent Endocytosis and Chemical Carcinogenesis

Background: Oxidative stress and generation of lipid peroxidation (LPO) products are detrimental in the pathogenesis of atherosclerosis and associated acute thrombotic events. However, recent studies suggest that moderate oxidative stress and low levels of LPO products can induce adaptive immune responses and exert beneficial effects. Tissue factor (TF) is a critical initiator of coagulation and aberrant TF expression on vascular cells under inflammation triggers intravascular thrombosis. HNE, a highly reactive LPO product and TF have been shown to be associated with atherosclerosis. Recently, we demonstrated that HNE decrypts procoagulant activity of pre-existing TF on activated monocytes and endothelial cells and generates TF+ microparticles. Here, we investigated the effect of HNE on induction of TF and cell adhesion molecules in monocytes and endothelial cells that were not perturbed earlier. Methods and results: THP-1 monocytic cells and endothelial cells (HUVEC) were stimulated with LPS and TNF-α/IL1-β, respectively, in the presence of a control vehicle or varying concentrations of HNE that are pathophysiologically relevant. TF induction was measured at mRNA (by qRT-PCR), protein (by immunoblotting) and activity levels (in factor X activation assay). Pre-treating cells with HNE inhibited TNF-α/IL1-β- or LPS-stimulated TF procoagulant activity in a dose-dependent manner. THP-1 and HUVEC varied in their sensitivities to HNE (THP-1> HUVEC). HNE-mediated inhibition of TF activity correlated with lower TF mRNA and protein levels. Our results demonstrate that HNE prevents TNF-α/IL1-β- and LPS-induced IKKβ degradation and thereby inhibits NFκβ activation. In addition to inhibiting TF expression, HNE significantly reduced monocyte adhesion to endothelial cells through downregulating TNF-α/IL1-β-induced expression of endothelial adhesion molecules VCAM-1 and ICAM-1. Conclusion: HNE may play a dual role in regulating TF activity in atherosclerosis. HNE could act as a prothrombotic mediator by increasing coagulant activity of pre-existing TF through decryption process. HNE can also elicit anti-thrombotic and anti-inflammatory effect by inhibiting TF and adhesion molecules in response to stimulus by impairing the NF-ĸB pathway.

Recent studies have suggested that antithrombin (AT) could act as a significant physiologic regulator of FVIIa. However, in vitro studies showed that AT could inhibit FVIIa effectively only when it was bound to tissue factor (TF). Circulating blood is known to contain only traces of TF, at best. FVIIa also binds endothelial cell protein C receptor (EPCR), but the role of EPCR on FVIIa inactivation by AT is unknown. The present study was designed to investigate the role of TF and EPCR in inactivation of FVIIa by AT in vivo. Low human TF mice (low TF, ∼ 1% expression of the mouse TF level) and high human TF mice (HTF, ∼ 100% of the mouse TF level) were injected with human rFVIIa (120 µg kg(-1) body weight) via the tail vein. At varying time intervals following rFVIIa administration, blood was collected to measure FVIIa-AT complex and rFVIIa antigen levels in the plasma. Despite the large difference in TF expression in the mice, HTF mice generated only 40-50% more of FVIIa-AT complex as compared to low TF mice. Increasing the concentration of TF in vivo in HTF mice by LPS injection increased the levels of FVIIa-AT complexes by about 25%. No significant differences were found in FVIIa-AT levels among wild-type, EPCR-deficient, and EPCR-overexpressing mice. The levels of FVIIa-AT complex formed in vitro and ex vivo were much lower than that was found in vivo. In summary, our results suggest that traces of TF that may be present in circulating blood or extravascular TF that is transiently exposed during normal vessel damage contributes to inactivation of FVIIa by AT in circulation. However, TF's role in AT inactivation of FVIIa appears to be minor and other factor(s) present in plasma, on blood cells or vascular endothelium may play a predominant role in this process.

Tuberculosis (TB) is a chronic lung infectious disease characterized by severe inflammation and lung granulomatous lesion formation. Clinical manifestations of TB include hypercoagulable states and thrombotic complications. We previously showed that Mycobacterium tuberculosis (M.tb) infection induces tissue factor (TF) expression in macrophages in vitro. TF plays a key role in coagulation and inflammation. In the present study, we investigated the role of TF in M.tb-induced inflammatory responses, mycobacterial growth in the lung and dissemination to other organs. Wild-type C57BL/6 and transgenic mice expressing human TF, either very low levels (low TF) or near to the level of wild-type (HTF), in place of murine TF were infected with M.tb via aerosol exposure. Levels of TF expression, proinflammatory cytokines and thrombin-antithrombin complexes were measured post M.tb infection and mycobacterial burden in the tissue homogenates were evaluated. Our results showed that M.tb infection did not increase the overall TF expression in lungs. However, macrophages in the granulomatous lung lesions in all M.tb-infected mice, including low TF mice, showed increased levels of TF expression. Conspicuous fibrin deposition in the granuloma was detected in wild-type and HTF mice but not in low TF mice. M.tb infection significantly increased expression levels of cytokines IFN-γ, TNF-α, IL-6 and IL-1ß in lung tissues. However, no significant differences were found in proinflammatory cytokines among the three experimental groups. Mycobacterial burden in lungs and dissemination into spleen and liver were essentially similar in all three genotypes. Our data indicate, in contrast to that observed in acute bacterial infections, that TF-mediated coagulation and/or signaling does not appear to contribute to the host-defense in experimental tuberculosis.

Objective—4-hydroxy-2-nonenal (HNE) is one of the major aldehydes formed during lipid peroxidation and is believed to play a role in the pathogenesis of atherosclerosis. The objective of the present study is to investigate the effect of HNE on tissue factor (TF) procoagulant activity expressed on cell surfaces. Approach and Results—TF activity and antigen levels on intact cells were measured using factor Xa generation and TF monoclonal antibody binding assays, respectively. Exposure of phosphatidylserine on the cell surface was analyzed using thrombin generation assay or by binding of a fluorescent dye–conjugated annexin V. 2′,7′-dichlorodihydrofluorescein diacetate was used to detect the generation of reactive oxygen species. Our data showed that HNE increased the procoagulant activity of unperturbed THP-1 cells that express traces of TF antigen, but had no effect on unperturbed endothelial cells that express no measurable TF antigen. HNE increased TF procoagulant activity but not TF antigen of both activated monocytic and endothelial cells. HNE treatment generated reactive oxygen species, activated p38 mitogen-activated protein kinase, and increased the exposure of phosphatidylserine at the outer leaflet in THP-1 cells. Treatment of THP-1 cells with an antioxidant, N-acetyl cysteine, suppressed the above HNE-induced responses and negated the HNE-mediated increase in TF activity. Blockade of p38 mitogen-activated protein kinase activation inhibited HNE-induced phosphatidylserine exposure and increased TF activity. Conclusions—HNE increases TF coagulant activity in monocytic cells through a novel mechanism involving p38 mitogen-activated protein kinase activation that leads to enhanced phosphatidylserine exposure at the cell surface.

The renal cell carcinoma (RCC) is one of the top 10 cancers in USA. The renal tumors are highly angiogenic and are resistant to conventional interventions, particularly radiotherapy. The advent of multi‐specific tyrosine kinase inhibitor sorafenib has improved the progression‐free survival in RCC, but overall survival in recurrent and metastatic RCC is still a concern that has lead to characterization of combinatorial regimens. Hence, we studied the effect of combination of nutlin‐3, an MDM2 inhibitor, which increases p53 levels, and sorafenib in RCC. Sorafenib along with nutlin‐3 synergistically inhibited the cell survival and enhanced caspase‐3 cleavage leading to apoptosis in RCC. Nutlin‐3 and sorafenib were more effective in reducing the migration of RCC, in combination than as single agents. Sorafenib and nutlin‐3 decreased the phosphorylation of vascular endothelial growth factor receptor‐2 (VEGFR‐2) and ERK along with inducing p53 activity. The sorafenib and nutlin‐3 co‐treatment lead to enhanced levels of p53, p‐p53, and increase in the levels of p53 pro‐apoptotic effector PUMA, Bax, and decrease in the anti‐apoptotic Bcl‐2 levels. Importantly, our studies revealed that sorafenib alone can activate p53 in a concentration dependent manner. Thus, co‐treatment of nutlin‐3 with sorafenib leads to increased half‐life of p53, which in turn can be activated by sorafenib, to induce downstream pro‐apoptotic and anti‐proliferative effects. This is the first report showing the synergistic effect of sorafenib and nutlin‐3 while providing a strong clinical‐translational rationale for further testing of sorafenib and nutlin‐3 combinatorial regimen in human RCC. © 2011 Wiley Periodicals, Inc.

Background The loss of von Hippel–Lindau (VHL) protein function leads to highly vascular renal tumors characterized by an aggressive course of disease and refractoriness to chemotherapy and radiotherapy. Loss of VHL in renal tumors also differs from tumors of other organs in that the oncogenic cascade is mediated by an increase in the levels of hypoxia-inducible factor-2α (HIF2α) instead of hypoxia-inducible factor-1α (HIF1α). Methods and Principal Findings We used renal carcinoma cell lines that recapitulate the differences between mutant VHL and wild-type VHL genotypes. Utilizing a method relying on extracted peptide intensities as a label-free approach for quantitation by liquid chromatography–mass spectrometry, our proteomics study revealed regulation of key proteins important for cancer cell survival, proliferation and stress-resistance, and implicated differential regulation of signaling networks in VHL-mutant renal cell carcinoma. We also observed upregulation of cellular energy pathway enzymes and the stress-responsive mitochondrial 60-kDa heat shock protein. Finding reliance on glutaminolysis in VHL-mutant renal cell carcinoma was of particular significance, given the generally predominant dependence of tumors on glycolysis. The data have been deposited to the ProteomeXchange with identifier PXD000335. Conclusions and Significance Pathway analyses provided corroborative evidence for differential regulation of molecular and cellular functions influencing cancer energetics, metabolism and cell proliferation in renal cell carcinoma with distinct VHL genotype. Collectively, the differentially regulated proteome characterized by this study can potentially guide translational research specifically aimed at effective clinical interventions for advanced VHL-mutant, HIF2α-over-expressing tumors.

BACKGROUND:Recent studies show that activated factor VII (FVIIa) binds to the endothelial cell protein C receptor (EPCR) on the vascular endothelium; however, the importance of this interaction in hemostasis or pathophysiology is unknown. OBJECTIVE:The aim of the present study was to investigate the role of the FVIIa interaction with EPCR on the endothelium in mediating FVIIa transport from the circulation to extravascular tissues. METHODS:Wild-type, EPCR-deficient or ECPR-over-expressing mice were injected with human recombinant (r)FVIIa (120 μg kg(-1) body weight) via the tail vein. At varying time intervals after rFVIIa administration, blood and various tissues were collected to measure FVIIa antigen and activity levels. Tissue sections were analyzed by immunohistochemistry for FVIIa and EPCR. RESULTS:The data reveal that, after intravenous (i.v.) injection, rFVIIa rapidly disappears from the blood and associates with the endothelium in an EPCR-dependent manner. Immunohistochemical analyses revealed that the association of FVIIa with the endothelium was maximal at 30 min and thereafter progressively declined. The FVIIa association with the endothelium was undetectable at time points exceeding 24 h post-FVIIa administration. The levels of rFVIIa accumulated in tissue correlate with expression levels of EPCR in mice and FVIIa associated with tissues remained functionally active for periods of at least 7 days. CONCLUSIONS:The observation that an EPCR-dependent association of FVIIa with the endothelium is most pronounced soon after rFVIIa administration and subsequently declines temporally, combined with the retention of functionally active FVIIa in tissue homogenates for extended periods, indicates that FVIIa binding to EPCR on the endothelium facilitates the transport of FVIIa from circulation to extravascular tissues where TF resides.

It is well established that 4-hydroxynonenal (HNE) plays a major role in oxidative stress-induced signaling and the toxicity of oxidants. Surprisingly our recent studies also demonstrate that low levels of HNE generated during oxidative stress promote cell survival mechanisms and proliferation. Since the expression and secretion of VEGF is known to be affected by Oxidative stress, during present studies, we have examined dose dependent effect of HNE on VEGF expression and secretion in a model of retinal pigment epithelial (RPE) cells in culture. Results of these studies showed that while inclusion of 0.1 μM HNE in the medium caused increased secretion of VEGF, its secretion and expression was significantly suppressed in the presence of >5 μM HNE in the media. These concentration dependent hormetic effects of HNE on VEGF secretion could be blocked by the over expression of GSTA4-4 indicating that these effects were specifically attributed to HNE and regulated by GSTA4-4. VEGF secreted into the media showed angiogenic properties as indicated by increased migration and tube formation of HUVEC in matrigel when grown in media from RPE cells treated with 1 μM HNE. The corresponding media from GSTA4-4 over expressing RPE cells had no effect on migration and tube formation of HUVEC in matrigel. These results are consistent with earlier studies showing that at low concentrations, HNE promotes proliferative mechanisms and suggest that HNE induces VEGF secretion from RPE cells that acts in a paracrine fashion to induce angiogenic signaling mechanism in the endothelial cells. These findings may suggest a role of HNE and GSTA4-4 in oxidative stress induced proliferative retinopathies.

Renal cell carcinoma (RCC) is one of the top ten cancers prevalent in USA. Loss-of-function mutations in the von Hippel-Lindau (VHL) gene constitute an established risk factor contributing to 75% of total reported cases of RCC. Loss-of-VHL leads to a highly vascularized phenotype of renal tumors. Intake of citrus fruits has been proven to reduce the risk of RCC in multicenter international studies. Hence, we studied the effect of 2'-hydroxyflavanone (2HF), an active anticancer compound from oranges, in RCC. Our in vitro investigations revealed that 2HF suppresses VHL-mutant RCC to a significantly greater extent than VHL-wild-type RCC by inhibiting epidermal growth factor receptor signaling, which is increased due to VHL mutations in RCC. Our results also revealed for the first time, that 2HF inhibits glutathione S-transferase pi activity. 2HF reduced cyclin B1 and CDK4 levels and induced G2/M phase arrest in VHL-mutant RCC. Importantly, 2HF inhibited the angiogenesis in VHL-mutant RCC by decreasing vascular endothelial growth factor expression. Our in vivo studies in mice xenografts confirmed our in vitro results as evident by decreased levels of proliferation marker, Ki67 and angiogenic marker, CD31, in 2HF-treated mice xenografts of VHL-mutant RCC. 2HF also increased the expression of E-cadherin in VHL-mutant RCC, which would be of significance in restoring normal epithelial phenotype. Collectively, our in vitro and in vivo results revealed the potent antiproliferative, anti-angiogenic and prodifferentiation properties of 2HF in VHL-mutant RCC, sparing normal cells, which could have significant implications not only in the specific management of VHL-mutant RCC but also towards other VHL syndromes.

Normal cells continuously monitor the nature of their respective cellular microenvironment. They are equipped with an inherent molecular defense to detect changes that can precipitate and trigger an oncogenic cascade in the internal and external environment of cells. The process called anoikis unleashes many a characteristic molecular change in the cells which eventually program to cell death in response to cell detachment and inappropriate cellular attachment, both of which can otherwise potentiate the ability of cells to preferentially pursue a malignant course due to the release of molecular discipline which conforms them to a benign structural and functional spectrum. The initiation and propagation of signaling that serves as a switch to cell survival or cell death mediated by surveillance of cell microenvironment is comprised of many heterogeneous sets of molecules interacting mainly at the interface of cell-extracellular matrix. Transforming cells continuously reprogram their signaling characteristics in sensing and modulating the stimuli from cell surface molecules like integrins, cadherins and immunoglobulin family of cell adhesion molecules at adhesion complexes, which enables them to resist anoikis and metastasize to different organs. Actin cytoskeleton binds BIM and Bcl2 modifying factor (BMF), which are regulated by the adhesion status and consequent conformation of cytoskeleton in the cells. This review aims at an integrated synopsis of fundamental mechanisms of the critical interactions of cell surface molecules to facilitate a focused analysis of the differential regulation of signaling processes at cell-ECM junctions that collectively rein the anoikis resistance, which in turn impacts metastatic aggressiveness and drug resistance of tumors originating from respective organs.

Abstract Renal cell carcinoma (RCC) is one of the top ten cancers prevalent in USA. Loss-of-function mutation in the VHL is an established risk factor for RCC contributing to 75% of total reported cases of RCC. Loss of VHL leads to highly vascularized phenotype of renal tumors. Intake of oranges has been proven to reduce the risk of RCC in multi-center international clinical trials. Hence, we studied effects of 2HF, an active anti-cancer compound of oranges, in VHL- mutant RCC. Our in vitro investigations revealed that 2HF selectively inhibits VHL-mutant RCC by inhibiting EGFR signaling which is increased due to VHL mutations in RCC. Our results also revealed for the first time, that 2HF inhibits GSTπ activity. 2HF inhibited cyclin B1 and CDK4, and induced G2/M phase arrest in VHL-mutant RCC. Importantly, 2HF inhibited the angiogenesis in VHL-mutant RCC by decreasing VEGF expression. Our in vivo studies in mice xenografts confirmed our in vitro results as evident by decreased levels of proliferation marker, Ki67 and angiogenic marker CD31, in 2HF treated (0.01%, w/w) mice xenografts of VHL-mutant RCC. 2HF also increased the expression of E-cadherin in VHL-mutant RCC which would be of significance in restoring the normal epithelial phenotype. Collectively, our in vitro and in vivo results revealed the potent anti-proliferative and anti-angiogenic effects of 2HF in VHL-mutant RCC, sparing normal cells, which could have significant implications not only in the specific management of VHL-mutant RCC but also in treating other VHL syndromes with highly vascularized phenotype. (Supported in part by NIH grant CA 77495 (SA), CA 155350, Cancer Research Foundation of North Texas, and Institute for Cancer Research & the Joe & Jessie Crump Fund for Medical Education (SSS)) 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 3702. doi:10.1158/1538-7445.AM2011-3702

Neuroblastomas arise from the neural crest cells and represent the most common solid tumors outside the nervous system in children. The amplification of N-Myc plays a primary role in the pathogenesis of neuroblastomas, whereas acquired mutations of p53 lead to refractory and relapsed cases of neuroblastomas. In this regard, dietary compounds which can target N-Myc and exert anticancer effects independent of p53 status acquire significance in the management of neuroblastomas. Hence, we investigated the anticancer properties of the flavonoid didymin in neuroblastomas. Didymin effectively inhibited proliferation and induced apoptosis irrespective of p53 status in neuroblastomas. Didymin downregulated phosphoinositide 3-kinase, pAkt, Akt, vimentin, and upregulated RKIP levels. Didymin induced G2/M arrest along with decreasing the levels of cyclin D1, CDK4, and cyclin B1. Importantly, didymin inhibited N-Myc as confirmed at protein, mRNA, and transcriptional level by promoter–reporter assays. High-performance liquid chromatography analysis of didymin-treated (2 mg/kg b.w.) mice serum revealed effective oral absorption with free didymin concentration of 2.1 μmol/L. Further in vivo mice xenograft studies revealed that didymin-treated (2 mg/kg b.w.) animals had significant reductions in tumors size compared with controls. Didymin strongly inhibited the proliferation (Ki67) and angiogenesis (CD31) markers, as well as N-Myc expression, as revealed by the histopathologic examination of paraffin-embedded section of resected tumors. Collectively, our in vitro and in vivo studies elucidated the anticancer properties and mechanisms of action of a novel, orally active, and palatable flavonoid didymin, which makes it a potential new approach for neuroblastoma therapy (NANT) to target pediatric neuroblastomas. Cancer Prev Res; 5(3); 473–83. ©2011 AACR.

Abstract Abstract 532 Recombinant factor VIIa (FVIIa) has been demonstrated to be an effective hemostatic agent for treatment of severe hemophilia patients. Recent clinical studies suggest that the prophylactic use of FVIIa markedly reduces the number of bleeding episodes in hemophilic patients with inhibitors. Clinical evidence from hemophilic patients during prophylaxis and post-prophylaxis suggest that the hemostatic effect of FVIIa surpassed the short circulatory half-life of FVIIa. At present, mechanisms by which this phenomenon occurs are not precisely known. Our laboratory has formerly established that FVIIa is capable of binding to the endothelial protein C receptor (EPCR) on endothelial cells, yet the significance of this interaction in hemostasis, and especially in prophylaxis, is not fully understood. Recent studies from our laboratory using a murine model have demonstrated that pharmacologically administered FVIIa rapidly associates with the endothelium, enters into extravasculature where it can interact with TF, and remains functionally active in tissues for an extended period of time. The aim of the present study was to determine if interaction of FVIIa with EPCR on the endothelium and subsequent EPCR-dependent transcytosis serves as a mechanism by which pharmacologically administered FVIIa is transported to tissues and retained for greater periods of time compared to its circulatory half-life. We have employed transgenic murine lines, including EPCR-over expressing, EPCR-deficient, and wild-type (WT) mice, to investigate the function of EPCR in the biodistribution of FVIIa and its extended stay in tissues. Mice were injected with human FVIIa (120 μg/kg b.w.) via tail vein and at 30 min, 3 h, 8 h, and 24 h following FVIIa administration, blood was collected via cardiac puncture and various tissues were harvested for antigen and immunohistochemical analyses. Our studies reveal that, following intravenous injection, FVIIa rapidly disappears from plasma (plasma levels of FVIIa in WT mice at 30 min and 3 h post-injection were ∼ 15% and <1%, respectively, of that which was injected) and associates with the endothelium in an EPCR-dependent manner. At 30 min post-injection, plasma levels of FVIIa were significantly higher in EPCR-deficient mice as compared to WT mice whereas plasma FVIIa levels were significantly lower in EPCR-over expressing mice compared to WT mice, suggesting that EPCR facilitates the sequestration of FVIIa from the bloodstream. This EPCR-dependent decrease in plasma FVIIa coincides with an EPCR-dependent increase in antigen levels of FVIIa in tissue homogenates. FVIIa antigen in the lungs of EPCR-over expressing mice at 30 min following FVIIa administration was approximately 6-fold higher than that which was found in WT mice. At the corresponding time, FVIIa antigen in EPCR-deficient mice was approximately 35% lower than that which was measured in WT mice. FVIIa antigen in the lung tissue of EPCR-over expressing mice remained relatively stable or slightly increased at 3, 8 and 24 h post FVIIa administration. FVIIa levels in tissue homogenates of WT and EPCR-deficient mice remained significantly lower compared to EPCR-over expressing mice at all time points. Immunohistochemical analysis of lung, skin, and bone-joint sections revealed that association of FVIIa with the endothelium is more pronounced in EPCR-over expressing mice as compared to lesser, albeit appreciable, levels in WT mice; EPCR-deficient mice showed negligible association of FVIIa with the endothelium. Association of FVIIa with the endothelium in EPCR-over expressing mice was maximal at 30 min and was thereafter progressively reduced at each time point; FVIIa association with the endothelium was undetectable at 24 h post FVIIa administration. The observation that EPCR-dependent association of FVIIa with the endothelium is most pronounced soon after injection and subsequently declines time-wise, combined with the retention of FVIIa in tissue homogenates for extended periods, implies that FVIIa bound to the endothelium enters tissues in an EPCR-dependent manner. These findings put forward an EPCR-dependent mechanism by which pharmacologically administered FVIIa can relocate to and be retained within tissues where TF resides, which conceivably may prime coagulation thereby contributing to hemostasis. Disclosures: Hedner: Novo Nordisk: Consultancy. Rao:Novo Nordisk: Research Funding.

Purpose Characteristic hypoglycemia, hypotriglyceridemia, hypocholesterolemia, lower body mass, and fat as well as pronounced insulin-sensitivity of RLIP76−/− mice suggested to us the possibility that elevation of RLIP76 in response to stress could itself elicit metabolic syndrome (MSy). Indeed, if it were required for MSy, drugs used to treat MSy should have no effect on RLIP76−/− mice. Research Design and Methods Blood glucose (BG) and lipid measurements were performed in RLIP76+/+ and RLIP76−/− mice, using Ascensia Elite Glucometer® for glucose and ID Labs kits for cholesterol and triglycerides assays. The ultimate effectors of gluconeogenesis are the three enzymes: PEPCK, F-1,6-BPase, and G6Pase, and their expression is regulated by PPARγ and AMPK. The activity of these enzymes was tested by protocols standardized by us. Expressions of RLIP76, PPARα, PPARγ, HMGCR, pJNK, pAkt, and AMPK were performed by Western-blot and tissue staining. Results The concomitant activation of AMPK and PPARγ by inhibiting transport activity of RLIP76, despite inhibited activity of key glucocorticoid-regulated hepatic gluconeogenic enzymes like PEPCK, G6Pase and F-1,6-BP in RLIP76−/− mice, is a salient finding of our studies. The decrease in RLIP76 protein expression by rosiglitazone and metformin is associated with an up-regulation of PPARγ and AMPK. Conclusions/Significance All four drugs, rosiglitazone, metformin, gemfibrozil and atorvastatin failed to affect glucose and lipid metabolism in RLIP76−/− mice. Studies confirmed a model in which RLIP76 plays a central role in the pathogenesis of MSy and RLIP76 loss causes profound and global alterations of MSy signaling functions. RLIP76 is a novel target for single-molecule therapeutics for metabolic syndrome.

e13534 Background: A major challenge in the management of androgen-independent prostate cancer (AIPC) is the emergence of dose-limiting toxicities like febrile neutropenia while on i.v. docetaxel (DTL) treatment which has lead to investigation of alternate routes of DTL administration and drug combinations. Hence, we tested the potency of a novel flavonoid vicenin-2 (VCN-2) alone and in combination with oral DTL in AIPC.METHODSCell survival was tested at various drug concentrations to determine in vivo doses by MTT and colony forming assays in PC-3 cells which have been established from the bone metastases of a 62 yr old male Caucasian with grade IV metastatic AIPC. Protein levels were analyzed by Western blot. For in vivo model studies, nu/nu nude mice (n=20) were implanted with 2 x 106 PC-3 cells subcutaneously into one flank and divided in to 4 groups. From tenth day after implantation, each group (n=5) were treated with corn oil (control), VCN-2 (3 mg/m2), DTL (0.03 mg/m2) and VCN-2 plus DTL in corn oil orally on alternate day. Tumor growth and body weight were monitored everyday. On day 60, tumors were excised for histopathological examination.RESULTSVCN-2 alone inhibited the survival of AIPC (p<0.01). The combination of VCN-2 and DTL induced synergistic effect in AIPC both in vitro and in vivo (~90% inhibition, CI <1 [Chou-Talalay test], p<0.0001). Tumor lysate analysis revealed that VCN-2 and DTL inhibited critical signaling proteins like pIGF1R, pRb, pAkt, PCNA and cyclin D1 to a greater extent in combination than either drugs alone. Histology of tumor sections revealed decreased levels of PSMA, ki67, CD31 and increase in the pro-differentiation marker E-cadherin. No overt toxicity was observed due to co-administration of VCN-2 and DTL.CONCLUSIONSOral administration of VCN-2 and DTL is effective and tolerable in vivo model of advanced AIPC. The salient feature of this study was the potent synergistic effect of VCN-2 and a low dose of DTL (0.03 mg/m2 of DTL and 3 mg/m2 of VCN-2 orally on alternate days compared to clinical dose in AIPC: 75 mg/m2 of DTL i.v. once in 3 wks. plus 5 mg prednisone twice daily) which strongly supports further development of VCN-2 and DTL combinatorial regimens for clinical use in AIPC.

The present study was conducted to determine the efficacy of novel flavonoid vicenin-2 (VCN-2), an active constituent of the medicinal herb Ocimum Sanctum Linn or Tulsi, as a single agent and in combination with docetaxel (DTL) in carcinoma of prostate (CaP). VCN-2 effectively induced anti-proliferative, anti-angiogenic and pro-apoptotic effect in CaP cells (PC-3, DU-145 and LNCaP) irrespective of their androgen responsiveness or p53 status. VCN-2 inhibited EGFR/Akt/mTOR/p70S6K pathway along with decreasing c-Myc, cyclin D1, cyclin B1, CDK4, PCNA and hTERT in vitro. VCN-2 reached a level of 2.6±0.3μmol/l in serum after oral administration in mice which reflected that VCN-2 is orally absorbed. The i.v. administration of docetaxel (DTL), current drug of choice in androgen-independent CaP, is associated with dose-limiting toxicities like febrile neutropenia which has lead to characterization of alternate routes of administration and potential combinatorial regimens. In this regard, VCN-2 in combination with DTL synergistically inhibited the growth of prostate tumors in vivo with a greater decrease in the levels of AR, pIGF1R, pAkt, PCNA, cyclin D1, Ki67, CD31, and increase in E-cadherin. VCN-2 has been investigated for radioprotection and anti-inflammatory properties. This is the first study on the anti-cancer effects of VCN-2. In conclusion, our investigations collectively provide strong evidence that VCN-2 is effective against CaP progression along with indicating that VCN-2 and DTL co-administration is more effective than either of the single agents in androgen-independent prostate cancer.

Lipid peroxidation (LPO) end-product 4-hydroxynonenal (4-HNE) has been implicated in the mechanism of retinopathy. Lately it has been shown that besides being cytotoxic, 4-HNE plays an important role in oxidative stress-induced signaling. In this study, we have investigated the effect of 4-HNE on epidermal growth factor receptor (EGFR)-mediated signaling, its potential functional consequences, and the regulatory role of the 4-HNE metabolizing isozymes, glutathione S-transferase A4-4 (GSTA4-4) on this signaling in retinal pigment epithelial (RPE) cells. Our results showed that consistent with its known toxicity at relatively higher concentrations, 4-HNE induced cell death in RPE. However, at lower concentrations (as low as 0.1 μM) 4-HNE triggered phosphorylation of EGFR and activation of its down stream signaling components ERK1/2 and Akt that are known to be involved in cell proliferation. These effects of 4-HNE on EGFR could be attenuated by the over expression of GSTA4-4 that reduces intracellular levels of 4-HNE. Our results also indicated that 4-HNE-induced activation of EGFR is a protective mechanism against oxidative stress because EGFR, MEK, and PI3K inhibitors potentiated the toxicity of 4-HNE and also inhibited wound healing in a RPE cell model. These studies suggest that as an initial response to oxidative stress, 4-HNE induces protective mechanism(s) in RPE cells through EGFR-mediated signaling.

The search for p53-independent mechanism of cancer cell killing is highly relevant to pediatric neuroblastomas, where successful therapy is limited by its transformation into p53-mutant and a highly drug-resistant neoplasm. Our studies on the drug-resistant p53-mutant as compared with drug-resistant p53 wild-type neuroblastoma revealed a novel mechanism for resistance to apoptosis: a direct role of p53 in regulating the cellular concentration of proapoptotic alkenals by functioning as a specific and saturable allosteric inhibitor of the alkenal-glutathione conjugate transporter, RLIP76. The RLIP76-p53 complex was showed by both immunoprecipitation analyses of purified proteins and immunofluorescence analysis. Drug transport studies revealed that p53 inhibited both basal and PKCα-stimulated transport of glutathione conjugates of 4HNE (GSHNE) and doxorubicin. Drug resistance was significantly greater for p53-mutant as compared with p53 wild-type neuroblastoma cell lines, but both were susceptible to depletion of RLIP76 by antisense alone. In addition, inhibition of RLIP76 significantly enhanced the cytotoxicity of cisplatin. Taken together, these studies provide powerful evidence for a novel mechanism for drug and apoptosis resistance in p53-mutant neuroblastoma, based on a model of regulation of p53-induced apoptosis by RLIP76, where p53 is a saturable and specific allosteric inhibitor of RLIP76, and p53 loss results in overexpression of RLIP76; thus, in the absence of p53, the drug and glutathione-conjugate transport activities of RLIP76 are enhanced. Most importantly, our findings strongly indicate RLIP76 as a novel target for therapy of drug-resistant and p53-mutant neuroblastoma.

AbstractTargeted depletion of the RALBP1-encoded 76-kDa splice variant, RLIP76, causes marked and sustained regression of human xenografts of lung, colon, prostate, and kidney cancers without toxicity in nude mouse models. We proposed that the remarkable efficacy and broad spectrum of RLIP76-targeted therapy is because its glutathione-conjugate (GS-E) transport activity is required for clathrin-dependent endocytosis (CDE), which regulates all ligand-receptor signaling, and that RLIP76 is required not only for survival of cancer cells but also for their very existence. We studied RLIP76 mutant proteins and the functional consequences of their expression into RLIP76−/− MEFs, identified key residues for GS-E binding in RLIP76, established the requirement of RLIP76-mediated GS-E transport for CDE, and showed a direct correlation between GS-E transport activities with CDE. Depletion of RLIP76 nearly completely blocked signaling downstream of EGF in a CDE-dependent manner and Wnt5a signaling in a CDE-independent manner. The seminal prediction of this hypothesis—RLIP76−/− mice will be deficient in chemical neoplasia—was confirmed. Benzo[a]pyrene, dimethylbenzanthracene, and phorbol esters are ineffective in causing neoplasia in RLIP76−/−. PMA-induced skin carcinogenesis in RLIP76+/+ mouse was suppressed completely by depletion of either PKCα or RLIP76 by siRNA or antisense and could be restored by topical application of RLIP76 protein in RLIP76−/− mouse skin. Likewise, chemical pulmonary carcinogenesis was absent in female and nearly absent in male RLIP76−/− mice. In RLIP76−/− mice, p53, p38, and JNK activation did not occur in response to either carcinogen. Our findings show a fundamental role of RLIP76 in chemical carcinogenesis. Mol Cancer Ther; 10(1); 16–28. ©2011 AACR.