Synthesis of radiolabeled biphenylsulfonamide matrix metalloproteinase inhibitors as new potential PET cancer imaging agents

Novel matrix metalloproteinase (MMP) inhibitor radiotracers, (S)-3-methyl-2-(2',3',4'-methoxybiphenyl-4-sulfonylamino)-butyric acid [(11)C]methyl ester (1a-c), (S)-3-methyl-2-(2',3',4'-fluorobiphenyl-4-sulfonylamino)-butyric acid [(11)C]methyl ester (1d-f), and (S)-3-methyl-2-(4'-nitrobiphenyl-4-sulfonylamino)-butyric acid [(11)C]methyl ester (1g), a series of substituted biphenylsulfonamide derivatives, have been synthesized for evaluation as new potential positron emission tomography (PET) cancer imaging agents.     

Phenylbutyrates as potent,orally bioavailable vitronectin receptor (integrin alphavbeta3) antagonists

In our continuing efforts to identify small molecule vitronectin receptor antagonists, we have discovered a series of phenylbutyrate derivatives, exemplified by 16, which have good potency and excellent oral bioavailability (approximately 100% in rats). This new series is derived conceptually from opening of the seven-membered ring of SB-265123.     

Synthesis of beta-substituted cationic porphyrins and their interactions with DNA

The beta-substituted cationic porphyrins (7, 8 and 10) have been synthesized and their interactions with plasmid DNA investigated. We found that substituents at the beta-position of porphyrins (7 and 8) have apparently affected their interactions with DNA compared with non-beta-substituted porphyrins (10).     

Regulation of Ras signaling specificity by protein kinase C

Ras proteins have the capacity to bind to and activate at least three families of downstream target proteins: Raf kinases, phosphatidylinositol 3 (PI 3)-kinase, and Ral-specific guanine nucleotide exchange factors (Ral-GEFs). We have previously shown that the Ras/Ral-GEF and Ras/Raf pathways oppose each other upon nerve growth factor stimulation, with the former promoting proliferation and the latter promoting cell cycle arrest. Moreover, the pathways are not activated equally. While the Ras/Raf/Erk signaling pathway is induced for hours, the Ras/Ral-GEF/Ral signaling pathway is induced for only minutes. Here we show that this preferential down-regulation of Ral signaling is mediated, at least in part, by protein kinase C (PKC). In particular, we show that PKC activation by phorbol ester treatment of cells blocks growth factor-induced Ral activation while it enhances Erk activation. Moreover, suppression of growth factor-induced PKC activation enhances and prolongs Ral activation. PKC does not influence the basal activity of the Ral-GEF designated Ral-GDS but suppresses its activation by Ras. Interestingly, Ras binding to the C-terminal Ras binding domain of Ral-GDS is not affected by PKC activity. Instead, suppression of Ral-GDS activation occurs through the region N terminal to the catalytic domain, which becomes phosphorylated in response to phorbol ester treatment of cells. These findings identify a role for PKC in determining the specificity of Ras signaling by its ability to differentially modulate Ras effector protein activation.     

Identification of beta subunit of the rhesus monkey chorionic gonadotropin (rmCG)

Chorionic gonadotropin (CG) is a placental derived hormone that plays a crucial role in successful implantation and establishment of early pregnancy in the primates. The rhesus monkey was chosen as a model to understand the feasibility of developing human DNA immuno-contraceptive. The coding region of rhesus monkey CG -subunit (rmCG) was isolated by the TDRT-PCR method. The nucleotide sequence including the leader peptide was 499 nucleotide long and encoded 166 amino acids. In comparing with the previous known primates CG -subunits, the rmCG was the highest degree of homology with baboon CG -subunit at the deduced amino acid sequence (94%), 79.5% homology with human CG -subunit and 70.4% homology with marmoset monkey CG -subunit. The eukaryotic expression vector pCMV4-rmCG inserted full-coding cDNA sequence of rmCG was constructed, and the expression of rmCG -subunit in HeLa cells transient expressing system in vitro and BALB/c mice in vivo was determined. The results demonstrated that the recombinant PCMV4-rmCG eukaryotic expression vector could express rmCG -subunit in vitro and in vivo.     

IL-1 beta attenuates IFN-alpha beta-induced antiviral activity and STAT1 activation in the liver: involvement of proteasome-dependent pathway

IFN-alphabeta is the only established treatment for viral hepatitis; however, more than 60% of patients are poorly responsive. Because viral hepatitis is associated with inflammation, we hypothesized that inflammation may attenuate the efficacy of IFN therapy. To test this hypothesis, the effect of IL-1beta, one of the major proinflammatory cytokines, on IFN signaling pathway in the liver was examined. Administration of IL-1beta in vivo attenuated IFN-alphabeta-induced STAT1 tyrosine phosphorylation in the liver but not in the spleen. The inhibitory action of IL-1beta in vivo was not affected by depleting hepatic Kupffer cells, suggesting that IL-1beta may directly target IFN-alphabeta signaling in hepatocytes. Indeed, pretreatment of human hepatocellular carcinoma HepG2 cells with IL-1beta suppressed IFN-alphabeta-induced antiviral activity and antiviral protein MxA mRNA expression. Furthermore, IL-1beta attenuated IFN-alphabeta-induced STAT1 binding and tyrosine phosphorylation without affecting the level of STAT1 protein. This inhibitory effect can be reversed by pretreatment with either proteasome inhibitors or transfection of dominant negative NF-kappaB inducing kinase mutants. Taken together, these findings suggest that IL-1beta attenuates IFN-alphabeta-induced STAT1 activation by a proteasome-dependent mechanism. In view of high levels of IL-1beta in the serum or within the liver of patients with chronic liver diseases, attenuation of IFN-alphabeta signaling in the liver by IL-1beta could be one of the mechanisms underlying the resistance to IFN therapy in chronic hepatitis C, and IL-1beta could be a potential therapeutic target for improving the efficacy of IFN therapy.     

HCV全长NS3基因表达及在抗体检测中的应用

丙型肝炎病毒(HCV)是引起非甲非乙型肝炎的主要病原因子.被HCV感染的病例中,超过50%以上会引起持续性感染、慢性肝炎,最终可能引起肝硬化和肝细胞癌[1].HCV严重威胁人类健康,但目前对丙肝患者尚缺乏有效的治疗手段,因此,严格把好血源关,提高对丙肝患者检出的灵敏度,是阻止丙肝血源传播的有效手段.     

Membrane localization of Raf assists engagement of downstream effectors

We have previously described a small molecule-directed protein dimerization strategy, using coumermycin to juxtapose Raf fusion proteins containing the coumermycin-binding domain GyrB. Oligomerization of cytoplasmically localized Raf-GyrB fusion proteins leads to an increase in the kinase activity of both Raf and its substrate Mek. Surprisingly, more distal targets, such as Erk1 and Erk2, are not activated using this approach. Here we report that coumermycin-induced oligomerization of a membrane-localized Raf-GyrB fusion protein potently activated Erk1 and Erk2, up-regulated Fos protein levels, and induced expression of many immediate-early response genes. Thus, both membrane localization and oligomerization of Raf-GyrB are required to target Raf signals to downstream effectors. The ability to activate the entire Raf signal transduction cascade conditionally, using coumermycin-induced oligomerization, should prove useful for dissecting Raf-mediated effects on gene expression and cellular differentiation.