Xiang Gao

University of Pittsburgh, Pittsburgh, Pennsylvania, United States

Are you Xiang Gao?

Claim your profile

Publications (34)143.2 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study is to develop an improved drug delivery system for enhanced paclitaxel (PTX) loading capacity and formulation stability based on PEG5K-(vitamin E)2 (PEG5K-VE2) system. PEG5K-(fluorenylmethoxycarbonyl)-(vitamin E)2 (PEG5K-FVE2) was synthesized using lysine as the scaffold. PTX-loaded PEG5K-FVE2 micelles were prepared and characterized. Fluorescence intensity of Fmoc in the micelles was measured as an indicator of drug-carrier interaction. Cytotoxicity of the micelle formulations was tested on various tumor cell lines. The therapeutic efficacy and toxicity of PTX-loaded micelles were investigated using a syngeneic mouse model of breast cancer (4T1.2). Our data suggest that the PEG5K-FVE2 micelles have a low CMC value of 4 μg/mL and small sizes (~60 nm). The PTX loading capacity of PEG5K-FVE2 micelles was much higher than that of PEG5K-VE2 micelles. The Fmoc/PTX physical interaction was clearly demonstrated by a fluorescence quenching assay. PTX-loaded PEG5K-FVE2 micelles exerted more potent cytotoxicity than free PTX or Taxol formulation in vitro. Finally, intravenous injection of PTX-loaded PEG5K-FVE2 micelles showed superior anticancer activity compared with PEG5K-VE2 formulation with minimal toxicity in a mouse model of breast cancer. In summary, incorporation of a drug-interactive motif (Fmoc) into PEG5K-VE2 micelles represents an effective strategy to improve the micelle formulation for the delivery of PTX.
    The AAPS Journal 07/2014; Just Accepted. · 4.39 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The altered DNA damage response pathway in patients with Fanconi anemia (FA) may increase the toxicity of clinical radiotherapy. We quantitated oral cavity mucositis in irradiated Fanconi anemia Fancd2(-/-) mice, comparing this to Fancd2(+/-) and Fancd2(+/+) mice, and we measured distant bone marrow suppression and quantitated the effect of the intraoral radioprotector GS-nitroxide, JP4-039 in F15 emulsion. We found that FA mice were more susceptible to radiation injury and that protection from radiation injury by JP4-039/F15 was observed at all radiation doses. Adult 10-12-week-old mice, of FVB/N background Fancd2(-/-), Fancd2(+/-) and Fancd2(+/+) were head and neck irradiated with 24, 26, 28 or 30 Gy (large fraction sizes typical of stereotactic radiosurgery treatments) and subgroups received intraoral JP4-039 (0.4 mg/mouse in 100 μL F15 liposome emulsion) preirradiation. On day 2 or 5 postirradiation, mice were sacrificed, tongue tissue and femur marrow were excised for quantitation of radiation-induced stress response, inflammatory and antioxidant gene transcripts, histopathology and assay for femur marrow colony-forming hematopoietic progenitor cells. Fancd2(-/-) mice had a significantly higher percentage of oral mucosal ulceration at day 5 after 26 Gy irradiation (59.4 ± 8.2%) compared to control Fancd2(+/+) mice (21.7 ± 2.9%, P = 0.0063). After 24 Gy irradiation, Fancd2(-/-) mice had a higher oral cavity percentage of tongue ulceration compared to Fancd2(+/+) mice irradiated with higher doses of 26 Gy (P = 0.0123). Baseline and postirradiation oral cavity gene transcripts were altered in Fancd2(-/-) mice compared to Fancd2(+/+) controls. Fancd2(-/-) mice had decreased baseline femur marrow CFU-GM, BFUe and CFU-GEMM, which further decreased after 24 or 26 Gy head and neck irradiation. These changes were not seen in head- and neck-irradiated Fancd2(+/+) mice. In radiosensitive Fancd2(-/-) mice, biomarkers of both local oral cavity and distant marrow radiation toxicity were ameliorated by intraoral JP4-039/F15. We propose that Fancd2(-/-) mice are a valuable radiosensitive animal model system, which can be used to evaluate potential radioprotective agents.
    Radiation research. 06/2014;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report here that a simple, well-defined, and easy-to-scale up nanocarrier, PEG5000-lysyl-(α-Fmoc-ε-t-Boc-lysine)2 conjugate (PEG-Fmoc), provides high loading capacity, excellent formulation stability and low systemic toxicity for paclitaxel (PTX), a first-line chemotherapeutic agent for various types of cancers. 9-Fluorenylmethoxycarbonyl (Fmoc) was incorporated into the nanocarrier as a functional building block to interact with drug molecules. PEG-Fmoc was synthesized via a three-step synthetic route, and it readily interacted with PTX to form mixed nanomicelles of small particle size (25-30 nm). The PTX loading capacity was about 36%, which stands well among the reported micellar systems. PTX entrapment in this micellar system is achieved largely via an Fmoc/PTX π-π stacking interaction, which was demonstrated by fluorescence quenching studies and (13)C NMR. PTX formulated in PEG-Fmoc micelles demonstrated sustained release kinetics, and in vivo distribution study via near infrared fluorescence imaging demonstrated an effective delivery of Cy5.5-labled PTX to tumor sites. The maximal tolerated dose for PTX/PEG-Fmoc (MTD > 120 mg PTX/kg) is higher than those for most reported PTX formulations, and in vivo therapeutic study exhibited a significantly improved antitumor activity than Taxol, a clinically used formulation of PTX. Our system may hold promise as a simple, safe, and effective delivery system for PTX with a potential for rapid translation into clinical study.
    Biomaterials 05/2014; · 8.31 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We report here that a simple, well-defined, and easy-to-scale up nanocarrier, PEG5000-lysyl-(α-Fmoc-ε-t-Boc-lysine)2 conjugate (PEG-Fmoc), provides high loading capacity, excellent formulation stability and low systemic toxicity for paclitaxel (PTX), a first-line chemotherapeutic agent for various types of cancers. 9-Fluorenylmethoxycarbonyl (Fmoc) was incorporated into the nanocarrier as a functional building block to interact with drug molecules. PEG-Fmoc was synthesized via a three-step synthetic route, and it readily interacted with PTX to form mixed nanomicelles of small particle size (25–30 nm). The PTX loading capacity was about 36%, which stands well among the reported micellar systems. PTX entrapment in this micellar system is achieved largely via an Fmoc/PTX π–π stacking interaction, which was demonstrated by fluorescence quenching studies and 13C NMR. PTX formulated in PEG-Fmoc micelles demonstrated sustained release kinetics, and in vivo distribution study via near infrared fluorescence imaging demonstrated an effective delivery of Cy5.5-labled PTX to tumor sites. The maximal tolerated dose for PTX/PEG-Fmoc (MTD > 120 mg PTX/kg) is higher than those for most reported PTX formulations, and in vivo therapeutic study exhibited a significantly improved antitumor activity than Taxol, a clinically used formulation of PTX. Our system may hold promise as a simple, safe, and effective delivery system for PTX with a potential for rapid translation into clinical study.
    Biomaterials 01/2014; 35(25):7146–7156. · 8.31 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Micelles are attractive delivery systems for hydrophobic drugs due to their small size and the ease of application. However, the limited drug loading capacity and the intrinsic poor stability of drug-loaded formulations represent two major issues for some micellar systems. In this study, we designed and synthesized a micelle-forming PEG-lipopeptide conjugate with two Fmoc groups located at the interfacial region, and two oleoyl chains as the hydrophobic core. The significance of Fmoc groups as a broadly applicable drug-interactive motif that enhances the carrier-drug interaction was examined using eight model drugs of diverse structures. Compared with an analogue without carrying a Fmoc motif, PEG5000-(Fmoc-OA)2 demonstrated a lower value of critical micelle concentration and three-fold increases of loading capacity for paclitaxel (PTX). These micelles showed tubular structures and small particle sizes (∼70 nm), which can be lyophilized and readily reconstituted with water without significant changes in particle sizes. Fluorescence quenching study illustrated the Fmoc/PTX π-π stacking contributes to the carrier/PTX interaction, and drug-release study demonstrated a much slower kinetics than Taxol, a clinically used PTX formulation. PTX/PEG5000-(Fmoc-OA)2 mixed micelles exhibited higher levels of cytotoxicity than Taxol in several cancer cell lines and more potent inhibitory effects on tumor growth than Taxol in a syngeneic murine breast cancer model (4T1.2). We have further shown that seven other drugs can be effectively formulated in PEG5000-(Fmoc-OA)2 micelles. Our study suggests that micelle-forming PEG-lipopeptide surfactants with interfacial Fmoc motifs may represent a promising formulation platform for a broad range of drugs with diverse structures.
    The AAPS Journal 11/2013; · 4.39 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hepatic stellate cells (HSCs) are the major cell type involved in the production of extracellular matrix in liver. After liver injury, HSCs undergo transdifferentiation process from quiescent state to activated state, which plays an important role in liver fibrosis. Previous studies have shown that thymoquinone (TQ) might have protective effect against liver fibrosis in animal models; however, the underlying mechanism of action is not fully understood. The aim of this study is to examine whether TQ has any direct effect on HSCs. Our results showed that pretreatment of mice with TQ has protective effect against CCl4-induced liver injury compared to control group (untreated), which is consistent with previous studies. Moreover, our in vivo study showed that COL1A1 and α-SMA mRNA levels were significantly downregulated by TQ treatment. Similarly, in vitro study confirmed that TQ downregulated COL1A1, COL3A1 and α-SMA mRNA levels in activated rat HSCs and LX2 cells, an immortalized human hepatic stellate cell line. Pretreatment with TQ also inhibited the LPS-induced proinflammatory response in LX2 cells as demonstrated by reduced mRNA expression of IL-6 and MCP-1. Mechanistically, inactivation of NF-κB pathway is likely to play a role in the TQ-mediated inhibition of proinflammatory response in HSCs. Finally, we have shown that TQ inhibited the culture-triggered transdifferentiation of freshly isolated rat HSCs as shown by significant downregulation of mRNA expression of several fibrosis-related genes. In conclusion, our study suggests that TQ has a direct effect on HSCs, which may contribute to its overall antifibrotic effect.
    Phytomedicine: international journal of phytotherapy and phytopharmacology 10/2013; · 2.97 Impact Factor
  • Source
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Various PEG-Vitamin E conjugates including D-alpha-tocopheryl polyethylene glycol succinate 1000 (TPGS) have been extensively studied as a nonionic surfactant in various drug delivery systems. However, limited information is available about the structure-activity relationship of PEG-Vitamin E conjugates as a micellar formulation for paclitaxel (PTX). In this study, four PEG-Vitamin E conjugates were developed that vary in the molecular weight of PEG (PEG2K vs PEG5K) and the molar ratio of PEG/Vitamin E (1/1 vs 1/2) in the conjugates. These conjugates were systematically characterized with respect to CMC, PTX loading efficiency, stability, and their efficiency in delivery of PTX to tumor cells in vitro and in vivo. Our data show that PEG5K-conjugates have lower CMC values and are more effective in PTX loading with respect to both loading capacity and stability. The conjugates with two Vitamin E molecules also worked better than the conjugates with one molecule of Vitamin E, particularly for PEG2K-system. Furthermore, all of the PEG-Vitamin E conjugates can inhibit P-gp function with their activity being comparable to that of TPGS. More importantly, PTX-loaded PEG5K-VE2 resulted in significantly improved tumor growth inhibitory effect in comparison to PTX formulated in PEG2K-VE or PEG2K-VE2, as well as Cremophor EL (Taxol) in a syngeneic mouse model of breast cancer (4T1.2). Our study suggests that PEG5K-Vitmin E2 may hold promise as an improved micellar formulation for in vivo delivery of anticancer agents such as PTX.
    Molecular Pharmaceutics 06/2013; · 4.57 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: PURPOSE: To develop spherulite formulations to achieve high entrapment efficiency for both small and macromolecules as well as cell-type specific delivery. METHODS: Spherulites of various compositions were prepared, and lipid-PEG was incorporated through post-insertion. Calcein and FITC-labeled albumin were employed as model drugs for small and macromolecules. The spherulites were characterized with respect to entrapment efficiency, size, structure, and release kinetics, and the morphology was examined via cryo-EM. Finally, SV119-decorated spherulites were examined for their selective uptake by cancer cells. RESULTS: The spherulites are 170 ~ 290 nm in size. A loading efficiency of 55 ~ 60% can be consistently achieved for both calcein and albumin under optimized conditions. Cryo-EM shows the onion-like morphology consistent with the structure of multilamellar liposomes. A t1/2 of 39.3 h and 69.7 h in cargo release in serum was observed before and after PEG decoration, and incorporation of SV119 led to selective delivery of rhodamine-labeled spherulites to PC-3 tumor cells. CONCLUSIONS: Our optimized formulations may represent a platform with simple preparation approach, relatively small particle size, high drug loading efficiency for both low and high molecular weight agents, and slow release kinetics for selective delivery of various types of therapeutics to target cells.
    Pharmaceutical Research 04/2013; · 4.74 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: S-trans, trans-farnesylthiosalicylic acid (FTS) is a synthetic small molecule that acts as a potent and especially nontoxic Ras antagonist. It inhibits both oncogenically activated Ras and growth factor receptor-mediated Ras activation, resulting in the inhibition of Ras-dependent tumor growth. In this work, an FTS conjugate with poly(ethylene glycol) (PEG) through a labile ester linkage, PEG5K-FTS2(L), was developed. PEG5K-FTS2 conjugate readily forms micelles in aqueous solutions with a critical micelle concentration of 0.68 μM, and hydrophobic drugs such as paclitaxel (PTX) could be effectively loaded into these particles. Both drug-free and PTX-loaded micelles were spherical in shape with a uniform size of 20-30 nm. The release of PTX from PTX-loaded PEG5K-FTS2 micelles was significantly slower than that from Taxol formulation. In vitro cytotoxicity studies with several tumor cell lines showed that PEG5K-FTS2(L) was comparable to FTS in antitumor activity. Western immunoblotting showed that total Ras levels were downregulated in several cancer cell lines treated with FTS or PEG5K-FTS2(L). The micellar formulation of PTX exhibited more in vitro cytotoxic activity against several tumor cell lines compared with free PTX, suggesting a possible synergistic effect between the carrier and the codelivered drug. The antitumor activity of the PTX loaded PEG5K-FTS2(L) micelles in a syngeneic murine breast cancer model was found to be significantly higher than that of Taxol, which may be attributed to their preferential tumor accumulation and a possible synergistic effect between PEG5K-FTS2 carrier and loaded PTX.
    Bioconjugate Chemistry 03/2013; · 4.58 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: PEGylated lipopeptide surfactants carrying drug-interactive motifs specific for a peptide-nitroxide antioxidant, JP4-039, were designed and constructed to facilitate the solubilization of this drug candidate as micelles and emulsion nanoparticles. A simple screening process based on the ability that prevents the formation of crystals of JP4-039 in aqueous solution was used to identify agents that have potential drug-interactive activities. Several protected lysine derivatives possessing this activity were identified, of which α-Fmoc-ε-t-Boc lysine is the most potent, followed by α-Cbz- and α-iso-butyloxycarbonyl-ε-t-Boc-lysine. Using a polymer-supported liquid-phase synthesis approach, a series of synthetic lipopeptide surfactants with PEG headgroup, varied numbers and geometries of α-Fmoc or α-Cbz-lysyl groups located at interfacial region as the drug-interactive domains, and oleoyl chains as the hydrophobic tails were synthesized. All α-Fmoc-lysyl-containing lipopeptide surfactants were able to solubilize JP4-039 as micelles, with enhanced solubilizing activity for surfactants with increased numbers of α-Fmoc groups. The PEGylated lipopeptide surfactants with α-Fmoc-lysyl groups alone tend to form filamentous or wormlike micelles. The presence of JP4-039 transformed α-Fmoc-containing filamentous micelles into dots and barlike mixed micelles with substantially reduced sizes. Fluorescence quenching and NMR studies revealed that the drug and surfactant molecules were in close proximity in the complex. JP4-039-loaded emulsion carrying α-Cbz-containing surfactants demonstrated enhanced stability over drug-loaded emulsion without lipopeptide surfactants. JP4-039 emulsion showed a significant mitigation effect on mice exposed to a lethal dose of radiation. PEGylated lipopeptides with an interfacially located drug-interactive domain are therefore tailor-designed formulation materials potentially useful for drug development.
    Molecular Pharmaceutics 12/2012; · 4.57 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Paclitaxel (PTX) is one of the most effective chemotherapeutic agents for a wide spectrum of cancers, but its therapeutic benefit is often limited by severe side effects. We have developed a micelle-based PTX formulation based on a simple conjugate derived from polyethylene glycol 5000 (PEG(5K)) and embelin (EB). Embelin is a natural product and exhibits antitumor activity through blocking the activity of X-linked inhibitor of apoptosis protein (XIAP). PEG(5K)-EB(2) conjugate self-assembles to form stable micelles in aqueous solution and efficiently encapsulates hydrophobic drugs such as PTX. PEG(5K)-EB(2) micelles have a relatively low CMC of 0.002 mg/mL (0.35 μm) with sizes in the range of 20 ∼ 30 nm with or without loaded PTX. In vitro cell uptake study showed that the PEG(5K)-EB(2) micelles were efficiently taken up by tumor cells. In vitro release study showed that PTX formulated in PEG(5K)-EB(2) micelles was slowly released over 5 days with much slower release kinetics than that of Taxol formulation. PTX formulated in PEG(5K)-EB(2) micelles exhibited more potent cytotoxicity than Taxol in several cultured tumor cell lines. Total body near infrared fluorescence (NIRF) imaging showed that PEG(5K)-EB(2) micelles were selectively accumulated at tumor site with minimal uptake in major organs including liver and spleen. PTX-loaded PEG(5K)-EB(2) micelles demonstrated an excellent safety profile with a maximum tolerated dose (MTD) of 100-120 mg PTX/kg in mice, which was significantly higher than that for Taxol (15-20 mg PTX/kg). Finally, PTX formulated in PEG(5K)-EB(2) micelles showed superior antitumor activity compared to Taxol in murine models of breast and prostate cancers.
    Biomaterials 11/2012; · 8.31 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Embelin, identified primarily from the Embelia ribes plant, has been shown to be a natural small molecule inhibitor of X-linked inhibitor of apoptosis protein (XIAP). It is also a potent inhibitor of NF-κB activation, which makes it a potentially effective suppressor of tumor cell survival, proliferation, invasion, angiogenesis, and inflammation. However, embelin itself is insoluble in water, which makes it unsuitable for in vivo applications. In this work, we developed a novel micelle system through conjugating embelin to a hydrophilic polymer, poly(ethylene glycol) 3500 (PEG(3.5K)) through an aspartic acid bridge. The PEG(3.5k)-embelin(2) (PEG(3.5k)-EB(2)) conjugate readily forms micelles in aqueous solutions with a CMC of 0.0205 mg/mL. Furthermore, PEG(3.5k)-EB(2) micelles effectively solubilize paclitaxel (PTX), a model hydrophobic drug used in this study. Both drug-free and drug-loaded micelles were small in size (20-30 nm) with low polydispersity indexes. In vitro cytotoxicity studies with several tumor cell lines showed that PEG(3.5k)-EB(2) is comparable to embelin in antitumor activity and synergizes with PTX at much lower doses. Our results suggest that PEG-derivatized embelin may represent a novel and dual-functional carrier to facilitate the in vivo applications of poorly water-soluble anticancer drugs such as PTX.
    Bioconjugate Chemistry 06/2012; 23(7):1443-51. · 4.58 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The sigma-2 receptor is an attractive target for tumor imaging and targeted therapy because it is overexpressed in multiple types of solid tumors, including prostate cancer, breast cancer, and lung cancer. SV119 is a synthetic small molecule that binds to sigma-2 receptors with high affinity and specificity. This study investigates the utility of SV119 in mediating the selective targeting of liposomal vectors in various types of cancer cells. SV119 was covalently linked with polyethylene glycol-dioleyl amido aspartic acid conjugate (PEG-DOA) to generate a novel functional lipid, SV119-PEG-DOA. This lipid was utilized for the preparation of targeted liposomes to enhance their uptake by cancer cells. Liposomes with various SV119 densities (0, 1, 3, and 5 mole%) were prepared and their cellular uptake was investigated in several tumor cell lines. In addition, doxorubicin (DOX) was loaded into the targeted and unmodified liposomes, and the cytotoxic effect on the DU-145 cells was evaluated by MTT assay. Liposomes with or without SV119-PEG-DOA both have a mean diameter of approximately 90 nm and a neutral charge. The incorporation of SV119-PEG-DOA significantly increased the cellular uptake of liposomes by the DU-145, PC-3, A549, 201T, and MCF-7 tumor cells, which was shown by fluorescence microscopy and the quantitative measurement of fluorescence intensity. In contrast, the incorporation of SV119 did not increase the uptake of liposomes by the normal BEAS-2B cells. In a time course study, the uptake of SV119 liposomes by DU-145 cells was also significantly higher at each time point compared to the unmodified liposomes. Furthermore, the DOX-loaded SV119 liposomes showed significantly higher cytotoxicity to DU-145 cells compared to the DOX-loaded unmodified liposomes. SV119 liposomes were developed for targeted drug delivery to cancer cells. The targeting efficiency and specificity of SV119 liposomes to cancer cells was demonstrated in vitro. The results of this study suggest that SV119-modified liposomes might be a promising drug carrier for tumor-targeted delivery.
    International Journal of Nanomedicine 01/2012; 7:4473-85. · 4.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Liver fibrosis is a chronic disorder that is characterized by an alteration of the balance between fibrogenesis and fibrinolysis, which results in accumulation of excessive amounts of extracellular matrix (ECM) and distortion of the normal liver architecture. The activation and transformation of quiescent hepatic stellate cells (HSCs) into myofibroblast-like cells constitute a major mechanism for the increased production of ECM in the liver. The nuclear receptor farnesoid X receptor (FXR) shows potent antifibrotic activity in HSCs and protects animals in rodent models of liver fibrosis. However, the detailed mechanism remains incompletely understood. In this study, we report that treatment with 3-[2-[2-chloro-4-[[3-(2,6-dichlorophenyl)-5-(1-methylethyl)-4-isoxazolyl]methoxy]phenyl]ethenyl]benzoic acid (GW4064), a synthetic FXR ligand, led to up-regulation of microRNA-29a (miR-29a) in HSCs isolated from wild-type mice, rats, and humans but not from FXR(-/-) mice. miR-29a seems to play an inhibitory role in the regulation of ECM production because of the following: 1) transfection of HSCs with miR-29a mimic resulted in drastic down-regulation of the mRNA expression of several genes that encode ECM proteins; and 2) miR-29a significantly inhibited the expression of a reporter expression plasmid that contains the 3'-untranslated region of the corresponding ECM genes. Our results suggest that miR-29a is a FXR target gene because miR-29a promoter activity was significantly increased by pharmacologic or genetic activation of FXR. Functional analysis of human miR-29a promoter identified an imperfect inverted repeat spaced by one nucleotide DNA motif, inverted repeat-1 (5'-AGGTCAcAGACCT-3'), as a likely FXR-responsive element that is involved in miR-29a regulation. Our study uncovers a new mechanism by which FXR negatively regulates the expression of ECM in HSCs.
    Molecular pharmacology 07/2011; 80(1):191-200. · 4.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Esophagitis is a significant toxicity of radiation therapy for lung cancer. In this study, reduction of irradiation esophagitis in mice, by orally administered p53/Mdm2/Mdm4 inhibitor, BEB55, or the GS-nitroxide, JP4-039, was evaluated. BEB55 or JP4-039 in F15 (liposomal) formulation was administered intraesophageally to C57BL/6 mice prior to thoracic irradiation of 29 Gy × 1 or 11.5 Gy × 4 thoracic irradiation. Progenitor cells were sorted from excised esophagus, and nitroxide was quantified, by electron paramagnetic resonance (EPR). Mice with Lewis lung carcinoma (3LL) orthotopic lung tumors were treated with BEB55 or JP4-039 prior to 20 Gy to determine if the drugs would protect the tumor cells from radiation. Intraesophageal BEB55 and JP4-039 compared to formulation alone increased survival after single fraction (p=0.0209 and 0.0384, respectively) and four fraction thoracic irradiation (p=0.0241 and 0.0388, respectively). JP4-039 was detected in esophagus, liver, bone marrow, and orthotopic Lewis lung carcinoma (3LL) tumor. There was no significant radiation protection of lung tumors by BEB55 or JP4-039 compared to formulation only as assessed by survival (p=0.3021 and 0.3693, respectively). Thus, BEB55 and JP4-039 safely ameliorate radiation esophagitis in mice.
    In vivo (Athens, Greece) 01/2011; 25(6):841-8. · 1.15 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Total-body irradiation (TBI) doses in the range of 2-8 Gy are associated with a drop in peripheral blood counts, decreased bone marrow cellularity, and hematopoietic syndrome. Radiation mitigators must be safe for individuals likely to recover spontaneously. Female C57BL/6HNsd mice exposed to 9.0 and 9.15 Gy TBI, received intraperitoneal (10 mg/kg) JP4-039, a novel radiation mitigator, 24 hours after irradiation and were followed for hematopoietic recovery. Irradiated mice showed reduced peripheral blood lymphocytes and neutrophils and bone marrow cellularity at day 5. Serum electrolytes, liver and renal function tests showed no deleterious effect of JP4-039-after irradiation, and no reduction in survival compared to irradiated controls. Marrow recovery measured as cellularity, and hematopoietic colony-forming cells including primitive granulocyte-erythroid-megakaryocyte-monocytes (GEMM), reached pre-irradiation levels by day 30 in JP4-039 treated groups. Mice receiving single or multiple administrations of JP4-039 showed an early return of CFU-GEMM. JP4-039 (GS-Nitroxide) is a safe radiation mitigator in mice warranting studies in larger animals and potentially a Phase I Clinical Trial.
    In vivo (Athens, Greece) 01/2011; 25(3):315-23. · 1.15 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Mitochondrial targeted radiation damage protectors (delivered prior to irradiation) and mitigators (delivered after irradiation, but before the appearance of symptoms associated with radiation syndrome) have been a recent focus in drug discovery for (1) normal tissue radiation protection during fractionated radiotherapy, and (2) radiation terrorism counter measures. Several categories of such molecules have been discovered: nitroxide-linked hybrid molecules, including GS-nitroxide, GS-nitric oxide synthase inhibitors, p53/mdm2/mdm4 inhibitors, and pharmaceutical agents including inhibitors of the phosphoinositide-3-kinase pathway and the anti-seizure medicine, carbamazepine. Evaluation of potential new radiation dose modifying molecules to protect normal tissue includes: clonogenic radiation survival curves, assays for apoptosis and DNA repair, and irradiation-induced depletion of antioxidant stores. Studies of organ specific radioprotection and in total body irradiation-induced hematopoietic syndrome in the mouse model for protection/mitigation facilitate rational means by which to move candidate small molecule drugs along the drug discovery pipeline into clinical development.
    Frontiers in Oncology 01/2011; 1:59.
  • [Show abstract] [Hide abstract]
    ABSTRACT: The farnesoid X receptor (FXR), a member of the nuclear receptor superfamily, has been proposed to play an important role in the pathogenesis of cardiovascular diseases by regulating the metabolism and transport of cholesterol and triglyceride. Scavenger receptor class B type I (SR-BI), a high-density lipoprotein receptor, plays an important role in decreasing lipid metabolism-associated cardiovascular diseases by regulating reverse cholesterol transport. Recent studies have shown that SR-BI expression is upregulated by several nuclear receptors. However, the role of FXR in the regulation of SR-BI expression is not well known. In the present study, we investigate the regulation of SR-BI by FXR in hepatocyte and the corresponding mechanism. Treatment of human hepatoma cell line HepG2 with FXR ligands resulted in upregulation of SR-BI at the levels of both mRNA and protein. Reporter assays showed that activation of FXR significantly enhanced the SR-BI promoter activity. Electrophoretic mobility shift and chromatin immunoprecipitation assays indicated that FXR induced SR-BI expression by binding to a novel FXR element (FXRE), a directed repeat DNA motif, DR8 (-703 AGGCCAcgttctagAGCTCA -684). The in vivo experiment demonstrated that gavaging mice with a natural ligand of FXR increased SR-BI expression in liver tissues. FXR can directly upregulate SR-BI expression in hepatocyte, and DR8 is a likely novel FXRE that is involved in SR-BI regulation. FXR may serve as a novel molecular target for manipulating SR-BI expression in hepatocyte.
    Atherosclerosis 10/2010; 213(2):443-8. · 3.71 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Activation of hepatic stellate cells (HSCs) plays an important role in the development of cirrhosis through the increased production of collagen and the enhanced contractile response to vasoactive mediators such as endothelin-1 (ET-1). The farnesoid X receptor (FXR) is a member of the nuclear receptor superfamily that is highly expressed in liver, kidneys, adrenals, and intestine. FXR is also expressed in HSCs and activation of FXR in HSCs is associated with significant decreases in collagen production. However, little is known about the roles of FXR in the regulation of contraction of HSCs. We report in this study that treatment of quiescent HSCs with GW4064, a synthetic FXR agonist, significantly inhibited the HSC transdifferentiation, which was associated with an inhibition of the upregulation of ET-1 expression. These GW4064-treated cells also showed reduced contractile response to ET-1 in comparison to HSCs without GW4064 treatment. We have further shown that GW4064 treatment inhibited the ET-1-mediated contraction in fully activated HSCs. To elucidate the potential mechanism we showed that GW4064 inhibited ET-1-mediated activation of Rho/ROCK pathway in activated HSCs. Our studies unveiled a new mechanism that might contribute to the anti-cirrhotic effects of FXR ligands.
    PLoS ONE 01/2010; 5(11):e13955. · 3.53 Impact Factor

Publication Stats

455 Citations
143.20 Total Impact Points

Institutions

  • 2003–2014
    • University of Pittsburgh
      • • Pharmaceutical Sciences
      • • Department of Cell Biology and Physiology
      Pittsburgh, Pennsylvania, United States