Biomedical subjects

Ge Li

Publications and source records attributed to Ge Li.

At least 19 recordsLinked to original sources

PubMed2007

Phosphatase type 2A-dependent and -independent pathways for ATR phosphorylation of Chk1.

ATM and Rad3-related (ATR) is a regulatory kinase that, when activated by hydroxyurea, UV, or human immunodeficiency virus-1 Vpr, causes cell cycle arrest through Chk1-Ser(345) phosphorylation. We demonstrate here that of these three agents only Vpr requires protein phosphatase type 2A (PP2A) to activate ATR for Chk1-Ser(345) phosphorylation. A requirement for PP2A by Vpr was first shown with the PP2A-specific inhibitor okadaic acid, which reduced Vpr-induced G(2) arrest and Cdk1-Tyr(15) phosphorylation. Using small interference RNA to down-regulate specific subunits of PP2A indicated that the catalytic beta-isoform PP2A(Cbeta) and the A regulatory alpha-isoform PP2A(Aalpha) are involved in the G(2) induction, and these downregulations decreased the Vpr-induced, ATR-dependent phosphorylations of Cdk1-Tyr(15) and Chk1-Ser(345). In contrast, the same down-regulations had no effect on hydroxyurea- or UV-activated ATR-dependent Chk1-Ser(345) phosphorylation. Vpr and hydroxyurea/UV all induce ATR-mediated gammaH2AX-Ser(139) phosphorylation and foci formation, but down-regulation of PP2A(Aalpha) or PP2A(Cbeta) did not decrease gammaH2AX-Ser(139) phosphorylation by any of these agents or foci formation by Vpr. Conversely, H2AX down-regulation had little effect on PP2A(Aalpha/Cbeta)-mediated G(2) arrest and Chk1-Ser(345) phosphorylation by Vpr. The expression of vpr increases the amount and phosphorylation of Claspin, an activator of Chk1 phosphorylation. Down-regulation of either PP2A(Cbeta) or PP2A(Aalpha) had little effect on Claspin phosphorylation, but the amount of Claspin was reduced. Claspin may then be one of the phosphoproteins through which PP2A(Aalpha/Cbeta) affects Chk1 phosphorylation when ATR is activated by human immunodeficiency virus-1 Vpr.

Adaptor Proteins, Signal Transducing↗

PubMed2006

Discovery of 2-hydroxy-N,N-dimethyl-3-{2-[[(R)-1-(5- methylfuran-2-yl)propyl]amino]-3,4-dioxocyclobut-1-enylamino}benzamide (SCH 527123): a potent, orally bioavailable CXCR2/CXCR1 receptor antagonist.

Structure-activity studies on lead cyclobutenedione 3 led to the discovery of 4 (SCH 527123), a potent, orally bioavailable CXCR2/CXCR1 receptor antagonist with excellent cell-based activity. Compound 4 displayed good oral bioavailability in rat and may be a potential therapeutic agent for the treatment of various inflammatory diseases.

Administration, Oral↗

PubMed2006

Curcumin opens cystic fibrosis transmembrane conductance regulator channels by a novel mechanism that requires neither ATP binding nor dimerization of the nucleotide-binding domains.

Cystic fibrosis transmembrane conductance regulator (CFTR) chloride channels are essential mediators of salt transport across epithelia. Channel opening normally requires ATP binding to both nucleotide-binding domains (NBDs), probable dimerization of the two NBDs, and phosphorylation of the R domain. How phosphorylation controls channel gating is unknown. Loss-of-function mutations in the CFTR gene cause cystic fibrosis; thus, there is considerable interest in compounds that improve mutant CFTR function. Here we investigated the mechanism by which CFTR is activated by curcumin, a natural compound found in turmeric. Curcumin opened CFTR channels by a novel mechanism that required neither ATP nor the second nucleotide-binding domain (NBD2). Consequently, this compound potently activated CF mutant channels that are defective for the normal ATP-dependent mode of gating (e.g. G551D and W1282X), including channels that lack NBD2. The stimulation of NBD2 deletion mutants by curcumin was strongly inhibited by ATP binding to NBD1, which implicates NBD1 as a plausible activation site. Curcumin activation became irreversible during prolonged exposure to this compound following which persistently activated channels gated dynamically in the absence of any agonist. Although CFTR activation by curcumin required neither ATP binding nor heterodimerization of the two NBDs, it was strongly dependent on prior channel phosphorylation by protein kinase A. Curcumin is a useful functional probe of CFTR gating that opens mutant channels by circumventing the normal requirements for ATP binding and NBD heterodimerization. The phosphorylation dependence of curcumin activation indicates that the R domain can modulate channel opening without affecting ATP binding to the NBDs or their heterodimerization.

Adenosine Triphosphate↗

PubMed2006

Systematic replication study of reported genetic associations in prostate cancer: Strong support for genetic variation in the androgen pathway.

BACKGROUND: Association studies have become a common and popular method to identify genetic variants predisposing to complex diseases. Despite considerable efforts and initial promising findings, the field of prostate cancer genetics is characterized by inconclusive reports and no prostate cancer gene has yet been established. METHODS: We performed a literature review and identified 79 different polymorphisms reported to influence prostate cancer risk. Of these, 46 were selected and tested for association in a large Swedish population-based case-control prostate cancer population. RESULTS: We observed significant (P < 0.05) confirmation for six polymorphisms located in five different genes. Three of them coded for key enzymes in the androgen biosynthesis and response pathway; the CAG repeat in the androgen receptor (AR) gene (P = 0.03), one SNP in the CYP17 gene (P = 0.04), two SNPs in the SRD5A2 gene (P = 0.02 and 0.02, respectively), a deletion of the GSTT1 gene (P = 0.006), and one SNP in the MSR1 gene, IVS5-59C > A, (P = 0.009). CONCLUSIONS: Notwithstanding the difficulties to replicate findings in genetic association studies, our results strongly support the importance of androgen pathway genes in prostate cancer etiology.

Aged↗

PubMed2006

Discovery of [7-(2,6-dichlorophenyl)-5-methylbenzo [1,2,4]triazin-3-yl]-[4-(2-pyrrolidin-1-ylethoxy)phenyl]amine--a potent, orally active Src kinase inhibitor with anti-tumor activity in preclinical assays.

We describe the identification of [7-(2,6-dichlorophenyl)-5-methylbenzo [1,2,4]triazin-3-yl]-[4-(2-pyrrolidin-1-ylethoxy)phenyl]amine (3), a potent, orally active Src inhibitor with desirable PK properties, demonstrated activity in human tumor cell lines and in animal models of tumor growth.

Animals↗

PubMed2006

Protection of human islets from induction of apoptosis and improved islet function with HO-1 gene transduction.

BACKGROUND: Islet transplantation represents an ideal therapeutic approach for treatment of type 1 diabetes but islet function and regeneration may be influenced by necrosis or apoptosis induced by oxidative stress and other insults. Heme oxygenase-1 (HO-1) is the rate-limiting enzyme in the catabolism of heme into biliverdin, releasing free iron and carbon monoxide. It has also been reported to be an antioxidant enzyme which can improve the function of grafted islets by cytoprotection via free radical scavenging and apoptosis prevention. In the present study, we investigated whether transduction of HO-1 genes into human islets with an adenovirus vector has cytoprotective action on islets cultured in vitro and discuss this method of gene therapy for clinical islet transplantation. METHODS: Cadaveric pancreatic islets were isolated and purified in vitro. Transduction efficiency of islets was determined by infecting islets with adenovirus vector containing the enhanced green fluorescent protein gene (Ad-EGFP) at multiplicities of infection (MOI) of 2, 5, 10, or 20. Newly isolated islets were divided into three groups: EGFP group, islets transduced with Ad-EGFP using MOI = 20; HO-1 group, transduced with adenovirus vectors containing the human HO-1 gene using MOI = 20; and control group, mock transduced islets. Insulin release after glucose stimulation of the cell lines was determined by a radioimmunoassay kit and the stimulation index was calculated. Flow cytometry was used to detect apoptotic cells in the HO-1 group and in the control group after induction by recombinant human tumor necrosis factor-alpha (rTNFalpha) and cycloheximide (CHX) for 48 hours. RESULTS: Adenovirus vectors have a high efficiency of gene transduction into adult islet cells. Transduction of islets with the Ad-EGFP was most successful at MOI 20, at which MOI fluorescence was very intense on day 7 after transduction and EGFP was expressed in cultured islet cells for more than four weeks in vitro. The insulin release in the control group was (182.36 +/- 58.96) mIU/L after stimulation by high glucose media (16.7 mmol/L), while insulin release from the HO-1 group and the EGFP group were (270.09 +/- 89.37) mIU/L and (175.95 +/- 75.05) mIU/L respectively. Compared to the control group and the EGFP group, insulin release in the HO-1 group increased significantly (P < 0.05). After treatment with rTNFalpha and CHX the apoptotic ratio of islet cells was (63.09 +/- 10.86)% in the HO-1 group, significantly lower than (90.86 +/- 11.25)% in the control group (P < 0.05). CONCLUSIONS: Transduction of human islets with Ad-HO-1 can protect against TNF-alpha and CHX mediated cytotoxicity. The HO-1 gene also appears to facilitate insulin release from human islets. Transduction of donor islets with the adenovirus vector containing an HO-1 gene might have potential value in clinical islet transplantation.

Adenoviridae↗

PubMed2006

Activity and expression of urokinase-type plasminogen activator and matrix metalloproteinases in human colorectal cancer.

BACKGROUND: Matrix metalloproteinase-2 (MMP-2), matrix metalloproteinase-9 (MMP-9), and urokinase-type plasminogen activator (uPA) are involved in colorectal cancer invasion and metastasis. There is still debate whether the activity of MMP-2 and MMP-9 differs between tumors located in the colon and rectum. We designed this study to determine any differences in the expression of MMP-2, MMP-9 and uPA system between colon and rectal cancer tissues. METHODS: Cancer tissue samples were obtained from colon carcinoma (n = 12) and rectal carcinomas (n = 10). MMP-2 and MMP-9 levels were examined using gelatin zymography and Western blotting; their endogenous inhibitors, tissue inhibitor of metalloproteinase-2 (TIMP-2) and tissue inhibitor of metalloproteinase-1 (TIMP-1), were assessed by Western blotting. uPA, uPAR and PAI-1 were examined using enzyme-linked immunosorbent assay (ELISA). The activity of uPA was assessed by casein-plasminogen zymography. RESULTS: In both colon and rectal tumors, MMP-2, MMP-9 and TIMP-1 protein levels were higher than in corresponding paired normal mucosa, while TIMP-2 level in tumors was significantly lower than in normal mucosa. The enzyme activities or protein levels of MMP-2, MMP-9 and their endogenous inhibitors did not reach a statistically significant difference between colon and rectal cancer compared with their normal mucosa. In rectal tumors, there was an increased activity of uPA compared with the activity in colon tumors (P = 0.0266), however urokinase-type plasminogen activator receptor (uPAR) and plasminogen activator inhibitor-1 (PAI-1) showed no significant difference between colon and rectal cancer tissues. CONCLUSION: These findings suggest that uPA may be expressed differentially in colon and rectal cancers, however, the activities or protein levels of MMP-2, MMP-9, TIMP-1, TIMP-2, PAI-1 and uPAR are not affected by tumor location in the colon or the rectum.

Aged↗

PubMed2006

A novel type of PTD, common helix-loop-helix motif, could efficiently mediate protein transduction into mammalian cells.

Protein transduction domains (PTDs), such as HIV TAT PTD, have been widely used as delivery tools into living cells. Here we reported for the first time that the helix-loop-helix (HLH) domain of basic helix-loop-helix (bHLH) family was a novel type of PTD. Efficient internalization has been obtained with HLH domains derived from bHLH proteins, NeuroD/BETA2, Neurogenin3, and Mitf, in various cell types including stable cell lines and primary cells. Cellular uptake of HLH PTD was barely or slightly inhibited by the metabolic, phagocytosis, clathrin- or caveolar-endocytosis formation inhibitors, but significantly and substantially reduced by heparin and macropinocytosis inhibitor, which suggested important roles of cell surface glycosaminoglycans and macropinocytosis during the protein transduction. Furthermore, NeuroD proteins still preserved transcription activation after internalized into cells. Our results demonstrated a new motif of PTD different from previous models as cationic residues cluster or amphipathic helix. The HLH domain is also the characteristic of the bHLH family, which implied a large number of PTDs could be discovered in this family to fit different purposes, and some of them could be directly recruited to penetrate cell membrane according to their crucial roles in development such as NeuroD and Ngn3.

Animals↗

PubMed2006

Synthesis and structure-activity relationships of 3,4-diaminocyclobut-3-ene-1,2-dione CXCR2 antagonists.

A novel series of 3,4-diaminocyclobut-3-ene-1,2-diones was prepared and found to show potent inhibitory activity of CXCR2 binding and IL-8-mediated chemotaxis of a CXCR2-expressing cell line. Microsome stability and Caco2 studies were subsequently used to show that compounds of this chemotype are predicted to have good oral bioavailability and are thus suitable for pharmaceutical development.

Administration, Oral↗

PubMed2006

Experimental study on the action of allitridin against human cytomegalovirus in vitro: Inhibitory effects on immediate-early genes.

Garlic (Allium sativum) extraction has been reported having anti-HCMV efficacy. This study was aimed to investigate the effect of allitridin (diallyl trisulfide, a compound from A. sativum extraction) on the replication of HCMV and the expression of viral immediate-early genes. In HCMV plaque-reduction assay, allitridin appeared a dose-dependent inhibitory ability with EC(50) value of 4.2 microg/ml (selective index, SI=16.7). Time-of-addition and time-of-removal studies showed that allitridin inhibited HCMV replication in earlier period of viral cycle before viral DNA synthesis. Both immediate early gene (ie1) transcription and IEA (IE(1)72 and IE(2)86) expression was suppressed by allitridin, but not by GCV in a single HCMV cycle format. In addition, allitridin appeared stronger inhibition on IE(2)86 than on IE(1)72. Decrease of viral DNA load in infected cells was also detected under allitridin treatment, probably due to an indirect consequence of the reduction in ie gene transcription. In summary, this study indicated that allitridin has anti-HCMV activity and the mechanism is associated with suppression of ie gene transcription.

Allyl Compounds↗

PubMed2006

Delta-sarcoglycan is necessary for early heart and muscle development in zebrafish.

Delta-sarcoglycan, one member of the sarcoglycan complex, is a very conservative muscle-specific protein exclusively expressed in the skeletal and cardiac muscles of vertebrates. Mutations in sarcoglycans are known to be involved in limb-girdle muscular dystrophy (LGMD) and dilated cardiomyopathy (DCM) in humans. To address the role of delta-sarcoglycan gene in zebrafish development, we have studied expression pattern of delta-sarcoglycan in zebrafish embryos and examined the role of delta-sarcoglycan in zebrafish embryonic development by morpholino. Strong expression of delta-sarcoglycan was observed in various muscles including those of the segment, heart, eye, jaw, pectoral fin, branchial arches, and swim bladder in zebrafish embryo. Delta-sarcoglycan was also expressed in midbrain and retina. Knockdown of delta-sarcoglycan resulted in severe abnormality in both the cardiac and skeletal muscles. Some severe ones displayed serious morphological abnormality such as hypoplastic head, linear heart, very weak heartbeats, and runtish trunk, all dead within 5 dpf. Whole-mount in situ hybridization analysis showed that adaxial cells and muscle pioneers were affected in delta-sarcoglycan knockdown embryos. In addition, absence of delta-sarcoglycan protein severely delayed the cardiac development and influenced the differentiation of cardiac muscle, and the cardiac left-right asymmetry was dramatically changed in morpholino-treated embryos. These data together suggest that delta-sarcoglycan plays an important role in early heart and muscle development.

Animals↗

PubMed2006

[Transduction of heme oxygenase-1 gene to human Islet cells via adenovirus vector enhances anti-apoptosis function and insulin release].

OBJECTIVE: To investigate the effects of heme oxygenase-1 (HO-1) gene on human islets in vitro, and to explore the potential value of gene therapy in clinical islet transplantation. METHODS: Adenovirus vector carrying human HO-1 gene (Ad-HO-1) or EGPF (Ad-EGFP) were established respectively. Human cadaveric pancreases were isolated, purified, cultured, and divided into 3 groups to be transfected with Ad-HO-1, Ad-EGFP or blank vector. Human tumor necrosis factor and cyclohexamide (CHX) were added into the culture fluid of the pancreatic islets. 48 hours later the pancreatic islets were digested into single cells. Flow cytometry was used to detect the apoptosis. Glucose of the concentration of 16.7 mmol/L was added into the culture fluid of the 3 groups of islet cells. After 1-hour co-incubation radioimmunochemistry was used to detect the level of insulin in the supernatant. RESULTS: After stimulation of glucose the insulin concentration in the supernatant of the Ad-HO-1 group was 270 mIU/L +/- 89 mIU/L, significantly higher than those of the Ad-EGFP group (189 mIU/L +/- 88 mIU/L) and control group (182 mIU/L +/- 59 mIU/L, both P < 0.05). The apoptotic ratio of the Ad-HO-1 group was 63.1% +/- 10.9%, significantly lower than that of the control group (90.9% +/- 11.3%, P < 0.01) after treatment with TNFalpha and CHX. CONCLUSION: Transfection of Ad-HO-1 into human islets improves anti-apoptotic function in cultured human islets and promotes insulin release of human pancreatic islets.

Adenoviruses, Human↗

PubMed2006

Age and apolipoprotein E*4 allele effects on cerebrospinal fluid beta-amyloid 42 in adults with normal cognition.

BACKGROUND: Decreased cerebrospinal fluid (CSF) beta-amyloid 42 (A beta 42) concentration, but not A beta 40 concentration, is a biomarker for Alzheimer disease. This A beta 42 concentration decrease in CSF likely reflects precipitation of A beta 42 in amyloid plaques in brain parenchyma. This pathogenic plaque deposition begins years before the clinical expression of dementia in Alzheimer disease. Normal aging and the presence of the apolipoprotein E (APOE*4) allele are the most important known risk factors for Alzheimer disease. OBJECTIVE: To estimate the interactive effects of normal aging and presence of the APOE*4 allele on CSF A beta 42 concentration in adults with normal cognition across the life span. DESIGN: The CSF was collected in the morning after an overnight fast using Sprotte 24-g atraumatic spinal needles. The CSF A beta 42 and A beta 40 concentrations were measured in the 10th milliliter of CSF collected by sandwich enzyme-linked immunosorbent assay. The APOE genotype was determined by a restriction digest method. Subjects One hundred eighty-four community volunteers with normal cognition aged 21 to 88 years. RESULTS: The CSF A beta 42, but not the A beta 40, concentration decreased significantly with age. There was a sharp decrease in CSF A beta 42 concentration beginning in the sixth decade in subjects with the APOE*4 allele. This age-associated decrease in CSF A beta 42 concentration was significantly and substantially greater in subjects with the APOE*4 allele compared with those without the APOE*4 allele. CONCLUSION: These CSF A beta 42 findings are consistent with acceleration by the APOE*4 allele of pathogenic A beta 42 brain deposition starting in later middle age in persons with normal cognition.

Adult↗

PubMed2006

Transplantation of rat islets transduced with human heme oxygenase-1 gene using adenovirus vector.

OBJECTIVE: To investigate whether human heme oxygenase-1 (HO-1) gene has protective action on islets cultured in vitro, and to explore whether transduction of HO-1 gene to donor islets could enhance engrafted islets survival and suppress local lymphocytic infiltration in islet grafts. METHODS: Newly isolated rat islets were isolated from the Sprague-Dawley rats and were divided into 3 groups in vitro study as follows: enhanced green fluorescent protein (EGFP) group, islets transduced with adenovirus vectors containing EGFP gene using multiplicities of infection (MOI) = 2, 5, 10, and 20 to determine the transduction efficacy; HO-1 group, islets transduced with adenovirus vectors containing human HO-1 gene using MOI = 20; and control group, mock transduced islets. Flow cytometry was used to detect apoptotic cells after induction by recombinant human tumor necrosis factor-alpha (rTNF-alpha) and cycloheximide (CHX) for 48 hours. Diabetic recipients were randomly divided into the following groups: HO-1 group (n = 9), receiving islets transduced with recombinant adenovirus-HO-1; control group (n = 9), receiving mock transduced islets; and phosphate buffer solution (PBS) group (n = 6), receiving only 0.8 mL PBS. About 1200 rat islet equivalents were transplanted into each recipient rendered by streptozotocin using the portal vein as transplant site. Allograft survival, apoptosis, and the state of lymphocytic infiltration were analyzed. RESULTS: After treatment with rTNF-alpha and CHX, the apoptotic ratio of islet cells was 4.22% +/- 2.38% in the HO-1 group (MOI = 20), significantly lower than 23.81% +/- 8.51% in the control group (P < 0.05), and 28.76% +/- 14.76% in the EGFP group (MOI = 20; P < 0.05). Maintenance of normoglycemia was prolonged in the HO-1 group, indicated by results that islet survival time was 10.56 +/- 4.33 days significantly longer than that of untreated islets which was 5.33 +/- 4.18 days (P < 0.05). The lymphocytic infiltration degree in engrafted islets treated with HO-1 gene was lower than that in the control group. CONCLUSIONS: HO-1 gene overexpression in rat islets by adenovirus transduction can protect cultured islets against rTNF-alpha and CHX-mediated cytotoxicity. HO-1 gene has cytoprotective effects on engrafted islets, which could prolong engrafted islets survival in allogenic transplantation model, and diminish the degree of lymphocytic infiltration in islet grafts. These findings suggest a potential therapeutic application for HO-1 gene in improving islet survival/function in human islet transplantation.

Adenoviridae↗

PubMed2006

Amino acid 1-209 is essential for PDX-1-mediated repression of human CMV IE promoter activity.

AIM: To explore the different roles of pancreatic duodenal homeobox factors-1 (PDX-1) domains in PDX-1 mediated repression of human cytomegalovirus immediately early (CMV IE) promoter. METHODS: A series of truncated PDX-1 mutants were constructed. The binding of PDX-1 and CMV IE promoter was identified by electrophoretic mobility shift assay (EMSA). The dual-reporter assay was applied to examine the repression activities of PDX-1 mutants on CMV IE promoter. In addition, RNAi technology was used to specifically knock down the endogenous PDX-1 expression. RESULTS: The reporter assay indicated that compared to the mock controls (pEGFP-N2), overexpression of PDX-1 resulted in a 41% decrease of CMV IE promoter activity in the 293 cells (P< 0.05) and 43% decrease in HeLa cells (P< 0.05), and the repression levels of various truncated mutants played on CMV IE promoter were different. Specific knock down of the endogenous PDX-1 expression significantly restored the activity of CMV IE promoter. EMSA demonstrated that domain 3 is necessary for nuclear localization and DNA binding activity of PDX-1. However, binding of PDX-1 alone to CMV IE promoter was not sufficient to inhibit its transcriptional activity, and other domains of PDX-1 presented were also required. CONCLUSION: Our data suggested that the DNA binding activity of PDX-1 domain 3 and the cooperative binding of PDX-1 domain 1/2 with other proteins were required for PDX-1 mediated repression of CMV IE promoter.

Base Sequence↗

PubMed2006

Interactions of sequence variants in interleukin-1 receptor-associated kinase4 and the toll-like receptor 6-1-10 gene cluster increase prostate cancer risk.

Chronic or recurrent inflammation has been suggested as a causal factor in several human malignancies, including prostate cancer. Genetic predisposition is also a strong risk factor in the development of prostate cancer. In particular, Toll-like receptors (TLR), especially the TLR6-1-10 gene cluster, are involved in prostate cancer development. Interleukin-1 receptor-associated kinases (IRAK) 1 and 4 are critical components in the TLR signaling pathway. In this large case-control study, we tested two hypotheses: (a) sequence variants in IRAK1 and IRAK4 are associated with prostate cancer risk and (b) sequence variants in IRAK1/4 and TLR1-6-10 interacts and confers a stronger risk to prostate cancer. We analyzed 11 single nucleotide polymorphisms (four in IRAK1 and seven in IRAK4) among 1,383 newly diagnosed prostate cancer patients and 780 population controls in Sweden. Although the single-nucleotide polymorphisms in IRAK1 and IRAK4 alone were not significantly associated with prostate cancer risk, one single-nucleotide polymorphism in IRAK4, when combined with the high-risk genotype at TLR6-1-10, conferred a significant excess risk of prostate cancer. In particular, men with the risk genotype at TLR6-1-10 and IRAK4-7987 CG/CC had an odds ratio of 9.68 (P = 0.03) when compared with men who had wild-type genotypes. Our findings suggest synergistic effects between sequence variants in IRAK4 and the TLR 6-1-10 gene cluster. Although this study was based on a priori hypothesis and was designed to address many common issues facing this type of study, our results need confirmation in even larger studies.

Age Distribution↗

PubMed2006

Exploring structure-activity relationships of tricyclic farnesyltransferase inhibitors using ECLiPS libraries.

The development of structure-activity relationships (SARs) relating to the function of a biological protein is often a long and protracted undertaking when using an iterative medicinal chemistry approach. High throughput screening of ECLiPS (Encoded Combinatorial Libraries on Polymeric Support) libraries can be used to simplify this process. In this paper, we illustrate how a large ECLiPS library of 26,908 compounds, based on a tricyclic core structure, was used to define a multitude of SARs for the oncogenic target, farnesyltransferase (FTase). This library, FT-2, was prepared using a split-and-pool approach in which small molecules are constructed on resin that contains tag/linker constructs to track the synthetic process [1-5] Highly defined SARs were produced from this screen that enhanced our understanding of FTase binding site interactions. The pivotal compounds culled from this library were potent in both cell-free and cell-based FTase assays, selective over the closely related enzyme, geranylgeranyltransferase I (GGTase I), and inhibited the adherent-independent growth of a transformed cell line.

Alkyl and Aryl Transferases↗

PubMed2006

Effect of statins on Alzheimer's disease biomarkers in cerebrospinal fluid.

BACKGROUND: Treatment with HMG-CoA reductase inhibitors ("statins") has been variably associated with a reduced risk of Alzheimer's disease (AD) in epidemiologic studies and reduced amyloid-beta (Abeta) deposition in animal models of AD. Putative neuroprotective effects of statins may vary in relation to their ability to penetrate into the central nervous system (CNS). METHODS: We measured levels of cerebrospinal fluid (CSF) AD biomarkers following 14 weeks of treatment with simvastatin (a CNS permeant statin; n=10) at 40 mg/day or pravastatin (a CNS impermeant statin; n=13) at 80 mg/day in hypercholesterolemic subjects without dementia. RESULTS: Simvastatin, but not pravastatin, reduced CSF levels of phospho-tau-181 (p-tau181) in all subjects. There were no differences in CSF levels of total tau, Abeta42, Abeta40, soluble amyloid beta protein precursor (sAbetaPP) alpha or beta, or F2-isoprostanes. CONCLUSIONS: Statins may modulate the phosphorylation of tau in humans and this effect may depend on the CNS availability of the statin. These results suggest another mechanism by which statins may act to reduce the risk of AD.

Adult↗