参考文献

We have previously shown that 4-anilinoquinazolines can be potent inhibitors of vascular endothelial growth factor (VEGF) receptor (Flt-1 and KDR) tyrosine kinase activity. A novel subseries of 4-anilinoquinazolines that possess basic side chains at the C-7 position of the quinazoline nucleus have been synthesized. This subseries contains potent,nanomolar inhibitors of KDR (median IC(50) 0.02 microM,range 0.001-0.04 microM),which are comparatively less potent vs Flt-1 tyrosine kinase (median IC(50) 0.55 microM,range 0.02-1.6 microM). The compounds also retain some inhibitory activity against the tyrosine kinase associated to the endothelial growth factor receptor (EGFR) (median IC(50) 0.2 microM,range 0.075-0.8 microM) but demonstrate selectivity vs that associated to the FGF receptor 1 (median IC(50) 2.5 microM,range 0.9-19 microM). This selectivity profile is also evident in a growth factor-stimulated human endothelial cell (HUVEC) proliferation assay (i.e.,inhibition of VEGF textgreater EGF textgreater FGF),with inhibition of VEGF-induced proliferation being achieved at nanomolar concentrations (median IC(50) 0.06 microM). Further examination of compound 2 (ZD6474) in recombinant enzyme assays revealed excellent selectivity for the inhibition of KDR tyrosine kinase (IC(50) 0.04 microM) vs the kinase activity of erbB2,MEK,CDK-2,Tie-2,IGFR-1R,PDK,PDGFRbeta,and AKT (IC(50) range: 1.1 to textgreater100 microM). Anilinoquinazolines possessing basic C-7 side chains exhibited markedly improved aqueous solubility over previously described anilinoquinazolines possessing neutral C-7 side chains (up to 500-fold improvement at pH 7.4). In addition,aqueous solubility of the neutral fraction present at pH 7.4 of the basic subseries of anilinoquinazoline proved to be higher than that of the neutral analogue 1 (ZD4190). Oral administration of representative compounds to mice (50 mg/kg) produced plasma levels between 0.2 and 3 microM at 24 h after dosing. Our development candidate 2 demonstrated a very attractive in vitro profile combined with excellent solubility (330 microM at pH 7.4) and good oral bioavailability in rat and dog (textgreater 80 and textgreater 50%,respectively). This compound demonstrated highly significant,dose-dependent,antitumor activity in athymic mice. Once daily oral administration of 100 mg/kg of compound 2 for 21 days inhibited the growth of established Calu-6 lung carcinoma xenografts by 79% (P textless 0.001,Mann Whitney rank sum test),and substantial inhibition (36%,P textless 0.02) was evident with 12.5 mg/kg/day. View Publication

Oncogenic activation of the RET receptor tyrosine kinase is common in different human cancers. We found that the pyrazolo-pyrimidine PP1 inhibited RET-derived oncoproteins with a half maximal inhibitor concentration of 80 nM. Furthermore,RET/PTC3-transformed cells treated with 5 microM of PP1 lost proliferative autonomy and showed morphological reversion. PP1 prevented the growth of two human papillary thyroid carcinoma cell lines that carry spontaneous RET/PTC1 rearrangements and blocked anchorage-independent growth and tumorigenicity in nude mice of NIH3T3 fibroblasts expressing the RET/PTC3 oncogene. These findings suggest targeting RET oncogenes with PP1 or related compounds as a novel treatment strategy for RET-associated neoplasms. View Publication

In early life,a high susceptibility to infectious diseases as well as a poor capacity to respond to vaccines are generally observed as compared with observations in adults. The mechanisms underlying immune immaturity have not been fully elucidated and could be due to the immaturity of the T/B cell responses and/or to a defect in the nature and quality of Ag presentation by the APC. This prompted us to phenotypically and functionally characterize early life murine dendritic cells (DC) purified from spleens of 7-day-old mice. We showed that neonatal CD11c(+) DC express levels of costimulatory molecules and MHC molecules similar to those of adult DC and are able to fully maturate after LPS activation. Furthermore,we demonstrated that neonatal DC can efficiently take up,process,and present Ag to T cells in vitro and induce specific CTL responses in vivo. Although a reduced number of these cells was observed in the spleen of neonatal mice as compared with adults,this study clearly shows that neonatal DC have full functional capacity and may well prime Ag-specific naive T cells in vivo. View Publication

Vitamin C (ascorbic acid (AA)) is very popular for its antioxidant properties. Consequently,many other important aspects of this multifaceted molecule are often underestimated or even ignored. In the present paper,we have tried to bring to the foreground some of these aspects,including the peculiarities of the AA biosynthetic pathway in different organisms,the remarkable function of AA as a co-substrate of many important dioxygenases,the role of AA-regenerating enzymes and the known pathways of AA catabolism,as well as the intriguing function of AA in gene expression. View Publication

We have investigated the effects of thermal injury upon myelopoiesis. IL-3,GM-CSF,and IL-5 were used to stimulate myeloid colony formation. IL-3 induces early myeloid progenitors and a more developed myeloid progenitor,the granulocyte-macrophage colony-forming unit (GM-CFU),to multiply and develop into mature myeloid cells. GM-CSF induces GM-CFU to become mature myeloid cells,while IL-5 induces eosinophil progenitors to become mature eosinophils. Stem Cell Factor (SCF) + IL-6 and FLT3 ligand,which have no effect on colony formation by themselves,were used to enhance the effects of IL-3 and GM-CSF,respectively. We found that thermal injury increased the number of early myeloid progenitors and GM-CFU in the spleen with either IL-3 or GM-CSF as a stimulant. Thermal injury increased the number of early myeloid progenitors in the bone marrow when GM-CSF,but not IL-3,was used to stimulate colony growth. Also,thermal injury increased the numbers of eosinophil progenitors in rat spleen and bone marrow and increased splenic levels of IL-5 mRNA. View Publication

Potential pharmacological applications in the areas of oncology,dermatology,diabetes,and atherosclerosis of synthetic analogs of retinoic acid that target a specific nuclear receptor and/or biological response have generated great interest in the development of new retinoid and rexinoid drugs. The pan-retinoic acid receptor antagonist AGN 193109 has been previously reported to elevate CYP1A1 levels,implicating the aryl hydrocarbon receptor (AhR) as an additional target for this retinoid. AhR is a cytosolic ligand-dependent transcription factor that,in conjunction with the AhR nuclear translocator (Arnt),binds to dioxin response elements (DREs) located in the promoter region of target genes,such as CYP1A1,and induces their transcription. The purpose of these studies was to determine whether additional synthetic retinoids were capable of elevating CYP1A1 levels and to examine the mechanism of this increase in CYP1A. Two additional retinoids,AGN 190730 and AGN 192837,were found to be potent inducers of DRE-driven transcriptional activity; AGN 190730 was the most potent. Moreover,electrophoretic mobility-shift assays demonstrate that AGN 190730 can transform AhR into its active DNA recognition form. In addition,trypsin digestion of AGN 190730-treated AhR reveals a conformational change in the protein similar to the conformational change of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-bound AhR. Finally,competitive binding studies demonstrate that AGN 190730 can inhibit the binding of TCDD to AhR. The sum of the data demonstrates that some synthetic retinoids in addition to activating the retinoic acid receptor/retinoid X receptor pathway are capable of binding to AhR and activating the AhR/Arnt pathway. View Publication

BACKGROUND: Ex vivo expansion of cord blood (CB) hematopoietic stem and progenitor cells increases cell dose and may reduce the severity and duration of neutropenia and thrombocytopenia after transplantation. This study's purpose was to establish a clinically applicable culture system by investigating the use of cytokines,serum-free media,and autologous plasma for the expansion of CB cells and the engraftment of expanded product in nonobese diabetic/severe combined immunodeficient (NOD/SCID) mice. STUDY DESIGN AND METHODS: Enriched CB CD34+ cells were cultured in four media (Iscove's modified Dulbecco's medium with FCS,Gibco; X-Vivo-10,BioWhittaker; QBSF-60,Quality Biological; and StemSpan SFEM,Stem Cell Technologies) with four cytokine combinations (thrombopoietin [TPO],SCF,Flt-3 ligand [FL] with and without G-CSF,and/or IL-6). The effect of autologous CB plasma was also investigated. The read-out measures were evaluated on Days 8 and 12. After expansion at the optimized condition,cultured cells were transplanted into sublethally irradiated NOD/SCID mice. The engraftment of human CD45+ cells and subsets in the bone marrow,spleen,and peripheral blood was determined. RESULTS: QBSF-60 or StemSpan SFEM supported high yields of early progenitors (CD34+ cells,textlessor= 64.8-fold; CD34+CD38- cells,330-fold; CFU-granulocyte erythroid macrophage megakaryocyte [GEMM],248-fold) and CFUs of the myeloid (CFU-GM,407-fold) and erythroid (BFU/CFU-E,144-fold) lineages. The expansion of the megakaryocytic lineage was consistently higher in X-Vivo-10 (CFU-megakaryocyte,684-fold). Autologous plasma promoted colony formation but reduced CD34+ cells and CFU-GEMM. The addition of G-CSF or IL-6 improved cell yields; G-CSF was more effective for committed progenitors. Expansion products from cultures in QBSF-60 with the cytokines engrafted and differentiated into the myeloid and lymphoid lineages in NOD/SCID mice. CONCLUSION: The data supported the strategy of expansion. The optimized condition may be applicable to clinical expansion for the abrogation or reduction of posttransplant cytopenia. View Publication

STI571 is a 2-phenylalaminopyrimidine derivative that inhibits c-abl,Bcr-Abl,and platelet-derived growth factor receptor tyrosine kinases. Recently,inhibition of stem cell factor (SCF)-induced c-kit phosphorylation and cell proliferation by STI571 was reported in the human myeloid cell line MO7e. Because approximately 70% of acute myelogenous leukemia (AML) cases are c-kit positive,we evaluated in vitro effects of STI571 on c-kit-positive cell lines and primary AML blast cells. At concentrations textgreater5 microM,the drug marginally inhibited SCF-independent proliferation of cell lines and most of AML blasts. Treatment of AML cells with cytarabine and STI571 showed synergistic effect at low concentrations. Western blotting analysis documented a distinct band of M(r) 145,000 specific for c-kit in cell lines and in AML samples. There was no correlation between the level of the c-kit expression evaluated by Western blotting and percentage of c-kit-positive blasts as measured by flow cytometry. Neither in cell lines nor in primary AML cells,c-kit autophosphorylation was detectable under standard growth conditions. SCF-induced phosphorylation of c-kit in MO7e cells was inhibited by STI571. In a c-kit-positive AML-4 cell line,as well as in AML samples,c-kit phosphorylation was not induced by SCF exposure,suggesting that in these cases,the receptor could not be functionally activated. In conclusion,with the exception of MO7e,SCF did not induce phosphorylation of c-kit,and cell proliferation was not modulated in the presence of STI571. We did not detect any SCF-independent c-kit phosphorylation in our experimental systems. Consequently,STI571 exerted only a limited inhibitory effect on the cell growth. View Publication

Histone deacetylases (HDACs) play important roles in transcriptional regulation and pathogenesis of cancer. Thus,HDAC inhibitors are candidate drugs for differentiation therapy of cancer. Here,we show that the well-tolerated antiepileptic drug valproic acid is a powerful HDAC inhibitor. Valproic acid relieves HDAC-dependent transcriptional repression and causes hyperacetylation of histones in cultured cells and in vivo. Valproic acid inhibits HDAC activity in vitro,most probably by binding to the catalytic center of HDACs. Most importantly,valproic acid induces differentiation of carcinoma cells,transformed hematopoietic progenitor cells and leukemic blasts from acute myeloid leukemia patients. More over,tumor growth and metastasis formation are significantly reduced in animal experiments. Therefore,valproic acid might serve as an effective drug for cancer therapy. View Publication

Augmenting the host's natural immune response to viruses by the administration of exogenous cytokines such as interferon-alpha (IFN-alpha) is a strategy increasingly employed in antiviral therapeutics. Enhancing the release of endogenous cytokines is,however,an alternative approach. The imidazoquinolinamines imiquimod and resiquimod have demonstrated potency as inducers of IFN-alpha and other cytokines both in vitro and in vivo. Cytokine gene activation is mediated via the signal transducer and activator of transcription 1 (STAT-1) and involves the transcription factors NFkappaB and alpha4F1. Antiviral activity has been demonstrated against a variety of viruses,and clinical efficacy has been demonstrated against genital warts,herpes genitalis and molluscum contagiosum. Imiquimod is administered as a 5% cream (Aldara) and has been licensed for the treatment of anogenital warts in immunocompetent patients. Complete clearance of warts has been observed in up to half of treated patients with only local side effects reported. Resiquimod can be administered topically but also exists as an oral formulation. The range of potential infections for which these agents may have clinical utility includes chronic hepatitis C virus infection and Kaposi's sarcoma. In addition,the imidazoquinolinamines may find roles in the therapy of cancers and as vaccine adjuvants. View Publication