Bis(imino)pyridine cobalt-catalyzed dehydrogenative silylation of alkenes: scope, mechanism, and origins of selective allylsilane formation.

The aryl-substituted bis(imino)pyridine cobalt methyl complex, ((Mes)PDI)CoCH3 ((Mes)PDI = 2,6-(2,4,6-Me3C6H2-N═CMe)2C5H3N), promotes the catalytic dehydrogenative silylation of linear α-olefins to selectively form the corresponding allylsilanes with commercially relevant tertiary silanes such as (Me3SiO)2MeSiH and (EtO)3SiH. Dehydrogenative silylation of internal olefins such as cis- and trans-4-octene also exclusively produces the allylsilane with the silicon located at the terminus of the hydrocarbon chain, resulting in a highly selective base-metal-catalyzed method for the remote functionalization of C-H bonds with retention of unsaturation. The cobalt-catalyzed reactions also enable inexpensive α-olefins to serve as functional equivalents of the more valuable α, ω-dienes and offer a unique method for the cross-linking of silicone fluids with well-defined carbon spacers. Stoichiometric experiments and deuterium labeling studies support activation of the cobalt alkyl precursor to form a putative cobalt silyl, which undergoes 2,1-insertion of the alkene followed by selective ß-hydrogen elimination from the carbon distal from the large tertiary silyl group and accounts for the observed selectivity for allylsilane formation.

Generation of a functional and durable vascular niche by the adenoviral E4ORF1 gene.

Vascular cells contribute to organogenesis and tumorigenesis by producing unknown factors. Primary endothelial cells (PECs) provide an instructive platform for identifying factors that support stem cell and tumor homeostasis. However, long-term maintenance of PECs requires stimulation with cytokines and serum, resulting in loss of their angiogenic properties. To circumvent this hurdle, we have discovered that the adenoviral E4ORF1 gene product maintains long-term survival and facilitates organ-specific purification of PECs, while preserving their vascular repertoire for months, in serum/cytokine-free cultures. Lentiviral introduction of E4ORF1 into human PECs (E4ORF1(+) ECs) increased the long-term survival of these cells in serum/cytokine-free conditions, while preserving their in vivo angiogenic potential for tubulogenesis and sprouting. Although E4ORF1, in the absence of mitogenic signals, does not induce proliferation of ECs, stimulation with VEGF-A and/or FGF-2 induced expansion of E4ORF1(+) ECs in a contact-inhibited manner. Indeed, VEGF-A-induced phospho MAPK activation of E4ORF1(+) ECs is comparable with that of naive PECs, suggesting that the VEGF receptors remain functional upon E4ORF1 introduction. E4ORF1(+) ECs inoculated in implanted Matrigel plugs formed functional, patent, humanized microvessels that connected to the murine circulation. E4ORF1(+) ECs also incorporated into neo-vessels of human tumor xenotransplants and supported serum/cytokine-free expansion of leukemic and embryonal carcinoma cells. E4ORF1 augments survival of PECs in part by maintaining FGF-2/FGF-R1 signaling and through tonic Ser-473 phosphorylation of Akt, thereby activating the mTOR and NF-kappaB pathways. Therefore, E4ORF1(+) ECs establish an Akt-dependent durable vascular niche not only for expanding stem and tumor cells but also for interrogating the roles of vascular cells in regulating organ-specific vascularization and tumor neo-angiogenesis.

Effects of a proximal base on water oxidation and proton reduction catalyzed by geometric isomers of [Ru(tpy)(pynap)(OH2)]2+.

Basic difference: The importance of a pendent base in promoting proton-coupled electron-transfer reactions with low activation barriers has been discussed for H(+) reduction or H(2) oxidation in acetonitrile. Investigation of the interaction between a base positioned in the second coordination sphere of a complex and a water ligand in water oxidation reactions using geometric isomers of [Ru(tpy)(pynap)(OH(2))](2+) (see picture) gave intriguing results.

Oxidation state characterization of ruthenium 2-iminoquinone complexes through experimental and theoretical studies.

The synthesis of complexes [Ru(II)(trpy)(2-imino-4-tert-butylquinone)(Cl)](+) and [Ru(II)(trpy)(NIL)(OAc)](+) (where trpy = 2:2',6':2''-terpyridyl, NIL = 2-imino-4-tert-butylquinone, 2-imino-4-methylquinone, 2-iminoquinone, 2-imino-4-chloroquinone, 2-imino-5-chloroquinone, 2-imino-4,6-di-tert-butyl-N-phenyl-quinone, 2-imino-4,6-di-tert-butyl-N-(2'-trifluoromethylphenyl)-quinone) is reported. The oxidation states of these complexes, as well as the previously reported [Ru(III)(trpy)(2-iminosemiquinone)(Cl)](+) complex, are investigated by spectroscopic, electrochemical and theoretical methods resulting in the latter complex being reassigned as [Ru(II)(trpy)(2-iminoquinone)(Cl)](+). Evidence for the presence of two structural isomers was found for all complexes, and crystal structures for both isomers of the [Ru(II)(trpy)(2-imino-4-tert-butylquinone)(Cl)]ClO(4) complex are reported, as well as for the cis isomer of [Ru(II)(trpy)(2-imino-4,6-di-tert-butyl-N-phenyl-quinone)(OAc)]PF(6). Redox control is also demonstrated based on the Hammett parameters of the substituents on the 2-iminoquinone ligand.

Adenovirus-mediated delivery of an anti-V antigen monoclonal antibody protects mice against a lethal Yersinia pestis challenge.

Pneumonic plague, caused by inhalation of Yersinia pestis, represents a major bioterrorism threat for which no vaccine is available. Based on the knowledge that genetic delivery of monoclonal antibodies (MAbs) with adenovirus (Ad) gene transfer vectors results in rapid, high-level antibody expression, we evaluated the hypothesis that Ad-mediated delivery of a neutralizing antibody directed against the Y. pestis V antigen would protect mice against a Y. pestis challenge. MAbs specific for the Y. pestis V antigen were generated, and the most effective in protecting mice against a lethal intranasal Y. pestis challenge was chosen for further study. The coding sequences for the heavy and light chains were isolated from the corresponding hybridoma and inserted into a replication-defective serotype 5 human Ad gene transfer vector (AdalphaV). Western analysis of AdalphaV-infected cell supernatants demonstrated completely assembled antibodies reactive with V antigen. Following AdalphaV administration to mice, high levels of anti-V antigen antibody titers were detectable as early as 1 day postadministration, peaked by day 3, and remained detectable through a 12-week time course. When animals that received AdalphaV were challenged with Y. pestis at day 4 post-AdalphaV administration, 80% of the animals were protected, while 0% of control animals survived (P < 0.01). Ad-mediated delivery of a V antigen-neutralizing antibody is an effective therapy against plague in experimental animals and could be developed as a rapidly acting antiplague therapeutic.

Redox activation of alkene ligands in platinum complexes with non-innocent ligands.

The reactivity of metal olefin complexes with non-innocent ligands (NILs) was examined. Treatment of PtCl(2)(diene) with the deprotonated catechol or aminophenol ligands afforded the corresponding Pt(NIL)(diene) complexes. The Pt((t)BA(F)Ph)(COD), Pt((t)BA(F)Ph)(nbd), and Pt(O(2)C(6)H(2)(t)Bu(2))(COD) (H(2)(t)BA(F)Ph = 2-(2-trifluoromethyl)anilino-4,6-di-tert-butylphenol, H(2)O(2)C(6)H(2)(t)Bu(2) = 3,5-di-tert-butylcatechol) complexes were examined by cyclic voltammetry. Treatment of Pt((t)BA(F)Ph)(COD) or Pt((t)BA(F)Ph)(nbd) with AgPF(6) afforded the imino-semiquinones [Pt((t)BA(F)Ph)(COD)]PF(6) or [Pt((t)BA(F)Ph)(nbd)]PF(6), respectively. The [Pt((t)BA(F)Ph)(COD)] complex was unreactive toward nucleophiles, whereas the oxidized derivative, [Pt((t)BA(F)Ph)(COD)]PF(6), rapidly and stereospecifically added alkoxides at the carbon trans to the phenolate. The Pt((t)BA(F)Ph)(COD), [Pt((t)BA(F)Ph)(COD)]PF(6), Pt((t)BA(F)Ph)(C(8)H(12)OMe), and [Cp(2)Co][Pt((t)BA(F)Ph)(C(8)H(12)OMe)] complexes were characterized crystallographically.

Rapid/sustained anti-anthrax passive immunity mediated by co-administration of Ad/AAV.

Achieving both immediate and sustained protection against diseases caused by bacterial toxins and extracellular pathogens is a challenge in developing biodefense therapeutics. We hypothesized that a single co-administration of an adenovirus (Ad) vector and an adeno-associated virus (AAV) vector, both expressing a pathogen-specific monoclonal antibody, would provide rapid, persistent passive immunotherapy against the pathogen. In order to test this strategy, we used the lethal toxin of Bacillus anthracis as a target of a monoclonal antibody directed against the protective antigen (PA) component of the toxin, using co-administration of an Ad vector encoding an anti-PA monoclonal antibody (AdalphaPA) and an AAV vector encoding an anti-PA monoclonal antibody (AAVrh.10alphaPA). As early as 1 day after co-administration of AdalphaPA and AAVrh.10alphaPA to mice, serum anti-PA antibody levels were detectable, and were sustained through 6 months. Importantly, animals that received both vectors were protected against toxin challenge as early as 1 day after administration and throughout the 6 month duration of the experiment. These data provide a new paradigm of genetic passive immunotherapy by co-administration of Ad and AAV vectors, each encoding a pathogen-specific monoclonal antibody, as an effective approach for both rapid and sustained protection against a bio-terror attack.

Genetic delivery of the murine equivalent of bevacizumab (avastin), an anti-vascular endothelial growth factor monoclonal antibody, to suppress growth of human tumors in immunodeficient mice.

Vascular endothelial growth factor (VEGF) produced by tumor cells plays a central role in stimulating angiogenesis required for solid tumor growth. VEGF-specific antibodies inhibit tumor cell line growth in animal models and a humanized monoclonal anti-VEGF antibody (bevacizumab [Avastin]) is approved as a treatment for metastatic cancer. We hypothesized that administration of an adenoviral (Ad) vector expressing the murine monoclonal antibody equivalent of bevacizumab would suppress human tumor growth in vivo. The Ad vector (AdalphaVEGF) encodes the light chain and heavy chain cDNAs of monoclonal antibody A.4.6.1, a murine antibody that specifically recognizes human VEGF with the same antigen-binding site as bevacizumab. AdalphaVEGF efficacy in vivo was evaluated with A-673 rhabdomyosarcoma and DU 145 prostate carcinoma cells in human tumor cell xenografts in SCID mice. For both tumor models, AdalphaVEGF directed the expression of high anti-human VEGF IgG antibody titers in vivo, the numbers of mitotic nuclei and blood vessels in the tumor were significantly decreased (p < 0.05), tumor growth was suppressed (p < 0.05), and there was increased survival (p < 0.005). Thus, AdalphaVEGF, encoding a murine monoclonal antibody that is the equivalent of bevacizumab, effectively suppresses the growth of human tumors, suggesting gene therapy as an alternative to bevacizumab monoclonal antibody therapy.

Adenovirus-based genetic vaccines for biodefense.

The robust host responses elicited against transgenes encoded by (E1-)(E3-) adenovirus (Ad) gene transfer vectors can be used to develop Ad-based vectors as platform technologies for vaccines against potential bioterror pathogens. This review focuses on pathogens of major concern as bioterror agents and why Ad vectors are ideal as anti-bioterror vaccine platforms, providing examples from our laboratories of using Ad vectors as vaccines against potential bioterror pathogens and how Ad vectors can be developed to enhance vaccine efficacy in the bioterror war.

A Novel Small-Molecule Inhibitor Targeting CREB-CBP Complex Possesses Anti-Cancer Effects along with Cell Cycle Regulation, Autophagy Suppression and Endoplasmic Reticulum Stress.

Lung adenocarcinoma, the most common subtype of lung cancer, is the leading cause of cancer death worldwide. Despite attempts for the treatment of lung cancer which have been accumulating, promising new therapies are still needed. Here, we found that cyclic-AMP response element-binding protein (CREB)-CREB binding protein (CBP) transcription factors complex inhibitor, Naphthol AS-TR phosphate (NASTRp), is a potential therapeutic agent for lung cancer. We show that NASTRp inhibited oncogenic cell properties through cell cycle arrest with concomitant suppression of tumor-promoting autophagy with down-regulations of Atg5-12 and Atg7, and accumulation of p62 in human lung cancer cell lines. In addition, NASTRp induced expression of endoplasmic reticulum stress markers such as DDIT3/CHOP, and led to apoptosis along with Bim induction. These findings suggest that transcription factor/co-activator complex, CREB-CBP, can be a potential therapeutic target and its inhibition could be a novel therapeutic strategy for lung cancer.

Protective immunity evoked against anthrax lethal toxin after a single intramuscular administration of an adenovirus-based vaccine encoding humanized protective antigen.

Because of the need to develop a vaccine to rapidly protect the civilian population in response to a bioterrorism attack with Bacillus anthracis, we designed AdsechPA, a replication-deficient human serotype 5 adenovirus encoding B. anthracis protective antigen (PA) with codons optimized for expression in mammalian cells. With a single intramuscular administration to mice of 10(9) particle units of AdsechPA, a dose that can be scaled to human use, anti-PA antibodies were evoked more rapidly and at a higher level than with a single administration of the new U.S. military recombinant PA/Alhydrogel vaccine. Importantly, AdsechPA afforded approximately 2.7-fold more protection than the recombinant PA vaccine against B. anthracis lethal toxin challenge 4 weeks after a single vaccination. Even at 11 days postvaccination, AdsechPA provided some survival benefit, whereas the rPA/Alhydrogel vaccine provided none. In the context that equivalent human doses of Ad vectors have already been demonstrated to be safe in humans, a single administration of AdsechPA may provide the means to rapidly protect the civilian population against B. anthracis in response to a bioterrorism attack.

A RAS renaissance: emerging targeted therapies for KRAS-mutated non-small cell lung cancer.

Of the numerous oncogenes implicated in human cancer, the most common and perhaps the most elusive to target pharmacologically is RAS. Since the discovery of RAS in the 1960s, numerous studies have elucidated the mechanism of activity, regulation, and intracellular trafficking of the RAS gene products, and of its regulatory pathways. These pathways yielded druggable targets, such as farnesyltransferase, during the 1980s to 1990s. Unfortunately, early clinical trials investigating farnesyltransferase inhibitors yielded disappointing results, and subsequent interest by pharmaceutical companies in targeting RAS waned. However, recent advances including the identification of novel regulatory enzymes (e.g., Rce1, Icmt, Pdeδ), siRNA-based synthetic lethality screens, and fragment-based small-molecule screens, have resulted in a "Ras renaissance," signified by new Ras and Ras pathway-targeted therapies that have led to new clinical trials of patients with Ras-driven cancers. This review gives an overview of KRas signaling pathways with an emphasis on novel targets and targeted therapies, using non-small cell lung cancer as a case example.

"Quitting smoking will benefit your health": the evolution of clinician messaging to encourage tobacco cessation.

Illnesses that are caused by smoking remain as the world's leading cause of preventable death. Smoking and tobacco use constitute approximately 30% of all cancer-related deaths and nearly 90% of lung cancer-related deaths. Thus, improving smoking cessation interventions is crucial to reduce tobacco use and assist in minimizing the burden of cancer and other diseases in the United States. This review focuses on the existing research on framed messages to promote smoking cessation. Consistent with the tenets of prospect theory and recent meta-analysis, gain-framed messages emphasizing the benefits of quitting seem to be preferable when working with adult patients who smoke tobacco products. The evidence also suggests that moderators of treatment should guide framed statements made to patients. Meta-analyses have provided consistent moderators of treatment such as need for cognition, but future studies should further define the specific framed interventions that would be most helpful for subgroups of smokers. In conclusion, instead of using loss-framed statements like "Smoking will harm your health by causing problems like lung and other cancers, heart disease, and stroke," as a general rule, physicians should use gain-framed statements like "Quitting smoking will benefit your health by preventing problems like lung and other cancers, heart disease, and stroke."

Persistent suppression of ocular neovascularization with intravitreal administration of AAVrh.10 coding for bevacizumab.

Vascular endothelial growth factor (VEGF) plays an important role in the pathogenesis of neovascular age-related macular degeneration and diabetic retinopathy. Bevacizumab, an anti-VEGF monoclonal antibody, is efficacious for these disorders, but requires monthly intravitreal administration, with associated discomfort, cost, and adverse event risk. We hypothesized that a single intravitreal administration of adeno-associated virus (AAV) vector expressing bevacizumab would result in persistent eye expression of bevacizumab and suppress VEGF-induced retinal neovascularization. We constructed an AAV rhesus serotype rh.10 vector to deliver bevacizumab (AAVrh.10BevMab) and assessed its ability to suppress neovascularization in transgenic mice overexpressing human VEGF165 in photoreceptors. Intravitreal AAVrh.10BevMab directed long-term bevacizumab expression in the retinal pigmented epithelium. Treated homozygous mice had reduced levels of neovascularization, with 90±4% reduction 168 days following treatment. Thus, a single administration of AAVrh.10BevMab provides long-term suppression of neovascularization without the costs and risks associated with the multiple administrations required for the current conventional bevacizumab monoclonal drug delivery.

Protective immunity against a lethal respiratory Yersinia pestis challenge induced by V antigen or the F1 capsular antigen incorporated into adenovirus capsid.

The aerosol form of the bacterium Yersinia pestis causes pneumonic plague, a rapidly fatal disease that is a biothreat if deliberately released. At present, no plague vaccines are available for use in the United States, but subunit vaccines based on the Y. pestis V antigen and F1 capsular protein show promise when administered with adjuvants. In the context that adenovirus (Ad) gene transfer vectors have a strong adjuvant potential related to the ability to directly infect dendritic cells, we hypothesized that modification of the Ad5 capsid to display either the Y. pestis V antigen or the F1 capsular antigen on the virion surface would elicit high V antigen- or F1-specific antibody titers, permit boosting with the same Ad serotype, and provide better protection against a lethal Y. pestis challenge than immunization with equivalent amounts of V or F1 recombinant protein plus conventional adjuvant. We constructed AdYFP-pIX/V and AdLacZ-pIX/F1, E1(-), E3(-) serotype 5 Ad gene transfer vectors containing a fusion of the sequence for either the Y. pestis V antigen or the F1 capsular antigen to the carboxy-terminal sequence of pIX, a capsid protein that can accommodate the entire V antigen (37 kDa) or F1 protein (15 kDa) without disturbing Ad function. Immunization with AdYFP-pIX/V followed by a single repeat administration of the same vector at the same dose resulted in significantly better protection of immunized animals compared with immunization with a molar equivalent amount of purified recombinant V antigen plus Alhydrogel adjuvant. Similarly, immunization with AdLacZ-pIX/F1 in a prime-boost regimen resulted in significantly enhanced protection of immunized animals compared with immunization with a molar-equivalent amount of purified recombinant F1 protein plus adjuvant. These observations demonstrate that Ad vaccine vectors containing pathogen-specific antigens fused to the pIX capsid protein have strong adjuvant properties and stimulate more robust protective immune responses than equivalent recombinant protein-based subunit vaccines administered with conventional adjuvant, suggesting that F1-and/or V-modified capsid Ad-based recombinant vaccines should be considered for development as anti-plague vaccines.

Genetic delivery of bevacizumab to suppress vascular endothelial growth factor-induced high-permeability pulmonary edema.

High-permeability pulmonary edema causing acute respiratory distress syndrome is associated with high mortality. Using a model of intratracheal adenovirus (Ad)-mediated overexpression of human vascular endothelial growth factor (VEGF)-A(165) in mouse lung to induce alveolar permeability and consequent pulmonary edema, we hypothesized that systemic administration of a second adenoviral vector expressing an anti-VEGF antibody (AdalphaVEGFAb) would protect the lung from pulmonary edema. Pulmonary edema was induced in mice by intratracheal administration of AdVEGFA165. To evaluate anti-VEGF antibody therapy, the mice were treated intravenously with AdalphaVEGFAb, an adenoviral vector encoding the light and heavy chains of an anti-human VEGF antibody with the bevacizumab (Avastin) antigen-binding site. Lung VEGF-A(165) and phosphorylated VEGF receptor (VEGFR)-2 levels, histology, lung wet-to-dry weight ratios, and bronchoalveolar lavage fluid (BALF) levels of total protein were assessed. Administration of AdalphaVEGFAb to mice decreased AdVEGFA165-induced levels of human VEGF-A(165) and phosphorylated VEGFR-2 in the lung. Histological analysis of AdalphaVEGFAb-treated mice demonstrated a reduction of edema fluid in the lung tissue that correlated with a reduction of lung wet-to-dry ratios and BALF total protein levels. Importantly, administration of AdalphaVEGFAb 48 hr after induction of pulmonary edema with AdVEGFA165 was effective in suppressing pulmonary edema. Administration of an adenoviral vector encoding an anti-VEGF antibody that is the equivalent of bevacizumab effectively suppresses VEGF-A(165)-induced high-permeability pulmonary edema, suggesting that anti-VEGF antibody therapy may represent a novel therapy for high-permeability pulmonary edema.

Genetic control of wayward pluripotent stem cells and their progeny after transplantation.

The proliferative capacity of pluripotent stem cells and their progeny brings a unique aspect to therapeutics, in that once a transplant is initiated the therapist no longer has control of the therapy. In the context of the recent FDA approval of a human ESC trial and report of a neuronal-stem-cell-derived tumor in a human trial, strategies need to be developed to control wayward pluripotent stem cells. Here, we focus on one approach: direct genetic modification of the cells prior to transplantation with genes that can prevent the adverse events and/or eliminate the transplanted cells and their progeny.

Functional cystic fibrosis transmembrane conductance regulator expression in cystic fibrosis airway epithelial cells by AAV6.2-mediated segmental trans-splicing.

Cystic fibrosis is characterized by deficiency of the cystic fibrosis transmembrane conductance regulator (CFTR), a Cl(-) transporter. The packaging constraints of adeno-associated viral (AAV) vectors preclude delivery of both an active promoter and CFTR cDNA to target cells. We hypothesized that segmental trans-splicing, in which two AAV vectors deliver the 5' and 3' halves of the CFTR cDNA, could mediate splicing of two pre-mRNAs into a full-length, functional CFTR mRNA. Using a segmental trans-splicing 5' donor-3' acceptor pair that split the CFTR cDNA between exons 14a and 14b, cotransfection of donor and acceptor plasmids into CFTR(-) cells resulted in full-length CFTR message and protein. Microinjection of plasmids into CFTR(-) cells produced cAMP-activated Cl(-) conductance. Vectors created with an engineered human serotype, AAV6.2, were used to deliver CFTR donor and acceptor constructs, resulting in full-length CFTR mRNA and protein as well as cAMP-activated Cl(-) conductance in CFTR(-) cells, including human CF airway epithelial IB3-1 cells. Thus, segmental trans-splicing can be used with AAV vectors to mediate expression of CFTR, a strategy potentially applicable to individuals with CF.