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Fen Zhou

Publications and source records attributed to Fen Zhou.

9 recordsLinked to original sources
PubMed2006

Targeting lung cancer using an infectivity enhanced CXCR4-CRAd.

Conventional treatments are not adequate for the majority of lung cancer patients. Conditionally replicating adenoviruses (CRAds) represent a promising new modality for the treatment of neoplastic diseases, including non-small cell lung cancer. Specifically, following cellular infection, the virus replicates selectively in the infected tumor cells and kills the cells by cytolysis. Next, the progeny virions infect a new population of surrounding target cells, replicate again and eradicate the infected tumor cells while leaving normal cells unaffected. However, to date, there have been two main limitations to successful clinical application of these CRAd agents; i.e. poor infectivity and poor tumor specificity. Here we report the construction of a CRAd agent, CRAd-CXCR4.RGD, in which the adenovirus E1 gene is driven by a tumor-specific CXCR4 promoter and the viral infectivity is enhanced by a capsid modification, RGD4C. This agent CRAd-CXCR4.RGD, as expected, improved both of the viral infectivity and tumor specificity as evaluated in an established lung tumor cell line and in primary tumor tissue from multiple patients. As an added benefit, the activity of the CXCR4 promoter was low in human liver as compared to three other promoters regularly used for targeting tumors. In addition, this agent has the potential of targeting multiple other tumor cell types. From these data, the CRAd-CXCR4.RGD appears to be a promising novel CRAd agent for lung cancer targeting with low host toxicity.

Adenoviridae↗
PubMed2006

Formin-1 protein associates with microtubules through a peptide domain encoded by exon-2.

Formin family proteins coordinate actin filaments and microtubules. The mechanisms by which formins bind and regulate the actin cytoskeleton have recently been well defined. However, the molecular mechanism by which formins coordinate actin filaments and microtubules remains poorly understood. We demonstrate here that Isoform-Ib of the Formin-1 protein (Fmn1-Ib) binds to microtubules via a protein domain that is physically separated from the known actin-binding domains. When expressed at low levels in NIH3T3 fibroblasts, Fmn1-Ib protein localizes to cytoplasmic filaments that nocodazole disruption confirmed as interphase microtubules. A series of progressive mutants of Fmn1-Ib demonstrated that deletion of exon-2 caused dissociation from microtubules and a stronger association with actin membrane ruffles. The exon-2-encoded peptide binds purified tubulin in vitro and is also sufficient to localize GFP to microtubules. Exon-2 does not contain any known formin homology domains. Deletion of exon 5, 7, 8, the FH1 domain or FH2 domain did not affect microtubule binding. Thus, our results indicate that exon-2 of Fmn1-Ib encodes a novel microtubule-binding peptide. Since formin proteins associate with actin filaments through the FH1 and FH2 domains, binding to interphase microtubules through this exon-2-encoded domain provides a novel mechanism by which Fmn1-Ib could coordinate actin filaments and microtubules.

Actins↗
PubMed2005

Evidence of cardiovascular protection by moderate alcohol: role of nitric oxide.

Epidemiological evidence indicates that moderate alcohol consumption reduces the incidence of heart disease. Endothelial nitric oxide synthase (eNOS) is a key regulator of vascular homeostasis and myocardial functions through the controlled production of nitric oxide (*NO). These studies were conducted to determine if the apparent alcohol-associated cardioprotection is mediated, in part, through modulation of the eNOS protein and activity in the cardiovascular system. Rats were fed alcohol and eNOS protein and *NO production were evaluated at the end of 8 weeks. Myocardial and vascular function was assessed ex vivo in a subset of animals. Moderate alcohol improved postischemic myocardial systolic and diastolic function and attenuated the postischemic reduction in coronary vascular resistance. Moderate alcohol also enhanced maximum vascular relaxation by 26 +/- 0.2% and increased plasma *NO production concomitant with a greater than 2.5-fold increase in eNOS protein. Higher levels of alcohol impaired maximum vascular relaxation by 22 +/- 0.1%. These results suggest that moderate alcohol improves postischemic myocardial functions and increases *NO production by vascular endothelium. An increase in *NO may explain, at least in part, the cardioprotective benefits of moderate alcohol consumption.

Animals↗
PubMed2005

Incorporating the survivin promoter in an infectivity enhanced CRAd-analysis of oncolysis and anti-tumor effects in vitro and in vivo.

Conditionally replicating adenoviruses (CRAds) represent a promising new modality for the treatment of cancer. A key contribution in this regard was the introduction of tumor-selective viral replication for amplification of the initial inoculum. Specifically, following cellular infection, the virus replicates selectively in the infected tumor cells and kills the cells by cytolysis. Next, the progeny virions infect surrounding target cells, replicate and eradicate the infected tumor cells, leaving normal cells unaffected. However, to date there have been two limitations to clinical application of these CRAd agents; i.e., both infectivity and tumor specificity are poor. Survivin protein is a novel member of the inhibitor of apoptosis (IAP) protein family, which plays an important role in the survival of cancer cells and progression of malignancies. Previous data have shown the survivin promoter has high activities in multiple cancer cells with a low activity in mouse liver. In this study, we propose an improved CRAd agent to circumvent the obstacles. We constructed a novel CRAd agent, CRAd-Survivin-RGD, which contains both the survivin promoter (either the short version, S-S, or the long version, S-L) to selectively drive E1 gene expression in tumor cells and a capsid modification and RGD4C to specifically enhance the tumor infectivity of CRAd agents. Both CRAd agents (S-S and S-L) showed high replication rates in the breast cancer cell line, MDA-MB-361, and low promoter activity in both normal mouse and human liver, thus signifying the CRAd agents have the phenotype of 'tumor on/liver off'. In cytocidal experiments, the CRAd agents demonstrated a high cytocidal effect on multiple cancer cell lines, including the breast cancer cell line, MDA-MB-231; the glioma cell line, D65, the melanoma cell line, MEL-28; and mesothelioma, Meso2374. The results also showed the tumor growth was dramatically inhibited by intertumoral administration of the CRAd agents in a breast cancer (MDA-MB-361) xenograft animal model. These data clearly demonstrate that CRAd-Survivin-RGD is a potential novel therapeutic agent for treatment in many, but not all, human cancers.

Adenoviridae↗
PubMed2004

Transport across a polarized monolayer of Caco-2 cells by transferrin receptor-mediated adenovirus transcytosis.

Adenoviral vectors have a poor record of transgene delivery efficiency through physical barriers such as the epithelium or endothelium. We report here the construction of an adenoviral vector that has the capability to be transported across polarized epithelial monolayers of Caco-2 cells (a colon carcinoma cell line) by transcytosis. This transcytosis is transferrin receptor (TfR)-mediated with use of a bifunctional adaptor, soluble coxsackie adenovirus receptor (sCAR)-Tf, and is both temperature and iron dependent. Under experimental conditions, the adenoviral transcytosis was inhibited by pretreatment of Caco-2 cells with colchicine, an inhibitor of transcytosis, and was not enhanced by pretreatment with Brefeldin A (BFA), an enhancer of transcytosis. In these Caco-2 cells, the transcytosis rate was 0.3 +/- 1.3% (SD). The transcytosed adenoviruses remain biologically functional. These data suggest the potential clinical benefit under conditions where drug delivery is a challenge, such as within the airway epithelium, at the bladder lumen urothelial cell interface, and across the blood-brain barrier for clinical treatment of lung, urogenital, and brain disorders, respectively, by adenoviral transcytosis of transgene delivery.

ATPases Associated with Diverse Cellular Activitie↗
PubMed2004

Peroxynitrite inactivates tissue plasminogen activator.

UNLABELLED: Tissue plasminogen activator (tPA) has a prominent role in physiological fibrinolysis in vivo. Thrombosis has been associated with clinical scenarios (e.g., atherosclerotic disease) known to involve local decreases in tPA activity with concomitant formation of reactive nitrogen species such as peroxynitrite (OONO(-)), a molecule formed from nitric oxide and superoxide. We hypothesized that exposure of tPA to OONO(-) would result in a decrease in tPA activity. OONO(-) was generated with 3-morpholinosydnonimine (SIN-1), a molecule that produces both nitric oxide and superoxide. Recombinant tPA was incubated at 37 degrees C for 60 min with 0 microM SIN-1; 100 microM SIN-1; 100 microM SIN-1 and 4000 U/mL recombinant human superoxide dismutase; or 4000 U/mL recombinant human superoxide dismutase (n = 8 separate reactions per condition). Changes in tPA activity were assessed by addition of tPA samples to tissue factor-exposed human plasma and measuring clot fibrinolysis with a thrombelastograph. Exposure to SIN-1 resulted in a decrease in tPA-mediated fibrinolysis (<1% activity of tPA not exposed to SIN-1) that was significantly (P < 0.001) different from the other three conditions. There were no significant differences between the other conditions. We conclude that tPA is inhibited by OONO(-), and that OONO(-) may have a role in clinical thrombotic scenarios. IMPLICATIONS: Tissue plasminogen activator (tPA) has a prominent role in fibrinolysis in vivo. Thrombosis has been associated with clinical scenarios involving decreases in tPA activity with concomitant formation of the oxidant peroxynitrite. We determined that peroxynitrite decreased tPA activity via thrombelastography. Peroxynitrite-mediated tPA inactivation may have a role in thrombotic states.

Antioxidants↗
PubMed2004

Peroxynitrite decreases hemostasis in human plasma in vitro.

Coagulopathy has been associated with clinical scenarios that involve reactive nitrogen species such as peroxynitrite (OONO-). Further, OONO- decreases tissue factor and fibrinogen function in vitro. Thus, we hypothesized that exposure of plasma to the OONO- generated with 3-morpholinosydnonimine (SIN-1), a molecule that produces both nitric oxide and superoxide, would result in a decrease in hemostatic function via diminished coagulation protein activity. Hemostatic function of plasma exposed to SIN-1 (0, 1, 5, and 10 mM for 60 min at 37 degrees C) was assessed with thrombelastography, activated partial thromboplastin time, and prothrombin time in the presence or absence of superoxide dismutase (SOD) or an OONO- scavenger. SIN-1 exposure resulted in a significant (P < 0.05), dose-dependent decrease in plasma hemostatic function and concurrent significant (P < 0.05) decreases in activities of factor VII, factor VIII complex, and factor X. Fibrinogen concentration was not affected by SIN-1. Antithrombin and protein C activity also decreased significantly (P < 0.05). Coincubation with SOD or an OONO- scavenger significantly (P < 0.05) attenuated SIN-1 mediated changes in hemostasis and procoagulant/ anticoagulant activity. We conclude that OONO- may decrease hemostatic function in human plasma by nitration of key procoagulants and that OONO- may play a significant role in hemorrhagic states.

Blood Coagulation Factors↗
PubMed2002

Genetic interaction between the unstable v-Ha-RAS transgene (Tg.AC) and the murine Werner syndrome gene: transgene instability and tumorigenesis.

Tg.AC transgenic mice provide a sensitive assay for oncogenic agents and a convenient alternative to the two-stage initiation/promoter model of skin tumorigenesis. Although extensively used, this model has remained in part an enigma since mice that carry the Tg.AC transgene (consisting of v-Ha-Ras driven by an embryonic zeta-globin promoter) would not ordinarily be expected to develop skin and other adult tumors. Cloning and characterizing the inserted transgene has provided an insight into the Tg.AC phenotype. We find that the transgene is inserted into a Line-1 element in such a way as to create extended inverted repeats consisting of both transgene and Line-1 sequences. Such structures would be expected to contribute to the instability of the Tg.AC locus and we suggest that this instability is critical to the Tg.AC phenotype. Further, we strengthen this notion by introducing an inactivating mutation in the murine Wrn gene (a gene important in maintenance of genome stability) and showing that bigenic Tg.AC/Wrn(Deltahel/Deltahel) mice experience an eightfold increase in inactivating germline mutations at the Tg.AC locus. Similarly, Tg.AC/Wrn(Deltahel/Deltahel) mice that retain an intact and thus active Tg.AC locus experience a sharp increase in papillomas as compared to Tg.AC/Wrn(+/+) mice. This work demonstrates a genetic interaction between the instability of the multicopy transgene and the Werner Syndrome gene. From this, we conclude that genetic instability remains a key element in this tumor promoter model.

Animals↗