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HeLa Cell Line (hela + cell_line)
Selected AbstractsNovel well-defined glycopolymers synthesized via the reversible addition fragmentation chain transfer process in aqueous mediaJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2009Zhicheng Deng Abstract We describe here the direct synthesis of novel gluconamidoalkyl methacrylamides by reacting D -gluconolactone with aminoalkyl methacrylamides. The glycomonomers were then successfully polymerized via the reversible addition-fragmentation chain transfer process (RAFT) using 4-cyanopentanoic acid dithiobenzoate (CTP) as chain transfer agent and 4,4,-azobis(4-cyanovaleric acid) (ACVA) as the initiator in aqueous media. Well-defined polymers were obtained as revealed by gel permeation chromatography. Diblock copolymers were then synthesized by the macro-CTA approach. The cationic glycopolymers were subsequently used in the formation of nanostructures via the complexation with plasmid DNA. As noted by dynamic light scattering, monodisperse nanoparticles were obtained via the electrostatic interaction of the cationic glycopolymer with DNA. The sizes of the nanoparticles formed were found to be stable and independent of pH. In vitro cell viability studies of the glycopolymers were carried out using HELA cell lines. The RAFT synthesized glycopolymers and cationic glyco-copolymers revealed to be nontoxic. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 614,627, 2009 [source] Effect of prolonged hydroxytamoxifen treatment of MCF-7 cells on mitogen activated kinase cascadeINTERNATIONAL JOURNAL OF CANCER, Issue 5 2002Fanjaniriana Rabenoelina Abstract Resistance to the antiestrogen tamoxifen is the main stumbling block for the success of breast cancer therapy. We focused our study on cellular alterations induced by a prolonged treatment with the active tamoxifen metabolite hydroxytamoxifen (OHT). We show that a prolonged OHT treatment (for up to 7 days) led to a progressive increase in the level of phosphorylated p44/42 mitogen activated kinase (MAP kinase) induced by 10,7 M TPA stimulation, without any significant change in the protein level. This effect was also observed in MCF-7 cells grown first in medium containing dextran-coated charcoal-treated FCS (DCC medium) for 20 days prior to OHT treatment, indicating a specific effect of the antiestrogen and not an effect of estrogen deprivation. It was prevented by cotreatment with estradiol and not observed in the estrogen receptor negative HeLa cell line, suggesting that it was mediated by the estrogen receptor. TPA induced phosphorylation of MEK1/2 was also raised by OHT treatment, without any change in their protein level or Raf-1 and H-Ras levels. When the MCF-7R OHT resistant cell line was grown in antiestrogen containing medium, the level of phosphorylated p44/42 MAP kinase was also high but reversed when the antiestrogen was removed. The 2 other MAP kinase, JNK and P38 pathways were not affected in the same way by OHT treatment. In conclusion, our data reveal that a prolonged OHT treatment, by increasing p44/42 MAPK activity, affects a key step in the growth control of MCF-7 cells, although not sufficiently to overcome the growth inhibitory effect of the drug. © 2002 Wiley-Liss, Inc. [source] Cytotoxicity and apoptosis induction of some selected marine bacteria metabolitesJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2005J. Lin Abstract Aims:, To study the potential apoptosis effects of cytotoxic marine bacterial metabolites on human HeLa cell line. Methods and Results:, After HeLa cells were routinely cultured, tetrazolium-based colorimetric assay for cytotoxicity was performed to screen the marine bacteria extracts showing 12 strains active. To find the potential active strain with apoptosis mechanism, a battery of apoptosis assays, including AO/EB staining, TUNEL assay (terminal-deoxynucleotidyl transferase mediated nick end labelling), gel electrophoresis and flow cytometry, were used to determine whether apoptosis was involved in HeLa cell cytotoxicity of marine bacterial extracts. The results indicated that four strains could induce cell shrinkage, cell membrane blebbing, formation of apoptotic body and DNA fragmentation. Conclusions:, Crude extracts of 12 of 153 strains of marine bacteria showed cytotoxic effects with ID50 ranged from 77·20 to 199·84 ,g ml,1, in which eight strains of bacteria were associated bacteria. The metabolites in the strains of QD1-2, NJ6-3-1, NJ1-1-1 and SS6-4 were able to induce HeLa cells apoptosis. Furthermore, the assessment by flow cytometry indicated that the hypodiploid apoptotic cells increased in a time-dependent manner, suggesting that induced apoptosis occurred from 24 h to 48 h after the extracts treatment. Significance and Impact of the Study:, Our results suggested that the compounds from fermentation in these four marine bacterial strains could be candidates for developing apoptosis specific anti-tumour agents with lower toxicity. This study indicated that associated marine bacteria could be good source to find cytotoxic metabolites, and some cytotoxic marine bacterial metabolites could have apoptosis mechanisms. [source] Alcohol Suppresses IL-2,Induced CC Chemokine Production by Natural Killer CellsALCOHOLISM, Issue 9 2005Ting Zhang Background: Natural killer (NK) cells are a critical component of the host innate immune system. We investigated whether alcohol impairs NK cell function, particularly production of CC chemokines induced by interleukin (IL)-2, the natural ligands for CCR5 receptor. Methods: Primary NK cells and NK cell line (YTS) were cultured with or without alcohol (10 to 80 mM) for three hours. The culture supernatants were then harvested and used to treat human peripheral blood monocyte-derived macrophages and a HeLa cell line, which expresses CD4, CCR5, and CXCR4 receptors (MAGI cells). CC chemokine expression by YTS and primary NK cells treated with or without alcohol was analyzed with the real-time RT-PCR and ELISA. Ca2+i and Western blot assays were used to determine calcium-mediated intracellular signaling pathway and NF-,B p65 expression. HIV strains (Bal and UG024) were used to infect macrophages and MAGI cells. In addition, ADA (macrophage-tropic strain) and murine leukemia virus (MLV) envelope-pseudotyped HIV infection was carried out in macrophages. HIV infectivity was determined by HIV reverse transcriptase (RT) and ,-galactosidase activity assays. Results: Alcohol inhibited IL-2,induced CC chemokine (CCL3 and CCL4) expression by NK cells. Functional tests demonstrated that this reduced expression of CC chemokines was associated with diminished anti-HIV ability of NK cells. Alcohol also reduced the ability of NK cells to response to CCL3-mediated chemotaxis. Alcohol inhibited IL-2,induced NF-,B p65 protein expression and calcium mobilization by NK cells. Conclusions: Alcohol, through the inhibition of IL-2,induced NF-,B p65 protein expression and intracellular calcium mobilization, suppressed NK cell production of CC chemokines. This suppression of CC chemokine production was associated with diminished anti-HIV activity of NK cells. Thus, by inhibiting NK cell,mediated innate immunity against HIV, alcohol consumption may have a cofactor role in the immunopathogenesis of HIV disease. [source] A high throughput drug screen based on fluorescence resonance energy transfer (FRET) for anticancer activity of compounds from herbal medicineBRITISH JOURNAL OF PHARMACOLOGY, Issue 3 2007H Tian Background and purpose: We report the development of a very efficient cell-based high throughput screening (HTS) method, which utilizes a novel bio-sensor that selectively detects apoptosis based on the fluorescence resonance energy transfer (FRET) technique. Experimental approach: We generated a stable HeLa cell line expressing a FRET-based bio-sensor protein. When cells undergo apoptosis, they activate a protease called ,caspase-3'. Activation of this enzyme will cleave our sensor protein and cause its fluorescence emission to shift from a wavelength of 535 nm (green) to 486 nm (blue). A decrease in the green/blue emission ratio thus gives a direct indication of apoptosis. The sensor cells are grown in 96-well plates. After addition of different chemical compounds to each well, a fluorescence profile can be measured at various time-points using a fluorescent plate reader. Compounds that can trigger apoptosis are potential candidates as anti-cancer drugs. Key results: This novel cell-based HTS method is highly effective in identifying anti-cancer compounds. It was very sensitive in detecting apoptosis induced by various known anti-cancer drugs. Further, this system detects apoptosis, but not necrosis, and is thus more useful than the conventional cell viability assays, such as those using MTT. Finally, we used this system to screen compounds, isolated from two plants used in Chinese medicine, and identified several effective compounds for inducing apoptosis. Conclusions and Implications: This FRET-based HTS method is a powerful tool for identifying anti-cancer compounds and can serve as a highly efficient platform for drug discovery. British Journal of Pharmacology (2007) 150, 321,334. doi:10.1038/sj.bjp.0706988 [source] A designed curved DNA segment that is a remarkable activator of eukaryotic transcriptionFEBS JOURNAL, Issue 24 2006Noriyuki Sumida To identify artificial DNA segments that can stably express transgenes in the genome of host cells, we built a series of curved DNA segments that mimic a left-handed superhelical structure. Curved DNA segments of 288 bp (T32) and 180 bp (T20) were able to activate transcription from the herpes simplex virus thymidine kinase (tk) promoter by approximately 150-fold and 70-fold, respectively, compared to a control in a transient transfection assay in COS-7 cells. The T20 segment was also able to activate transcription from the human adenovirus type 2 E1A promoter with an 18-fold increase in the same assay system, and also activated transcription from the tk promoter on episomes in COS-7 cells. We also established five HeLa cell lines with genomes containing T20 upstream of the transgene promoter and control cell lines with T20 deleted from the transgene locus. Interestingly, T20 was found to activate transcription in all the stable transformants, irrespective of the locus. This suggests that the T20 segment may allow stable expression of transgenes, which is of importance in many fields, and may also be useful for the construction of nonviral vectors for gene therapy. [source] Synthesis and radiolabelling of Re(CO)3 - , -elemene derivatives as potential therapeutic radiopharmaceuticalsJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 5 2009Yunfeng Ren Abstract , -Elemene, (1S, 2S, 4R)-(,)-(1-methy-1-vinyl-2,4-diisopropenyl cyclohexane) is an anticancer agent from the Traditional Chinese Herb Medicinal. Three novel Re(CO)3 - , -elemene derivatives including their radioactive conjugates containing N,N,N tridentate ligands and tricarbonyl rhenium (complex 12, 13, 14) were synthesized. Their structures were characterized by infrared (IR), 1H-NMR and HRMS. Good radioactive yield (above 90%) and radioactive chemical purity with Re-188 (above 95%) were obtained for all of the three derivatives (complex 15, 16, 17). The antiproliferative activity of non-radioactive , -elemene-Re(CO)3 derivatives on Lewis lung cancer cells and HeLa cell lines were evaluated by WST-1 methods. The result shows substantial decrease in IC50 values compared with the parent compound , -elemene. The synthesis and radiosynthesis of , -elemene tricarbonyl rhenium conjugates provide the possibility to find a new kind of potential radiopharmaceuticals on , -elemene. Copyright © 2009 John Wiley & Sons, Ltd. [source] Synthesis and Biological Studies of N -Alkylated Cyclic DiaminesCHEMISTRY & BIODIVERSITY, Issue 1 2007Xiao-Qin Xiong Abstract Several alkyl-substituted mesocyclic diamines were synthesized, and their interaction with DNA were studied by melting-temperature measurements and the ethidium bromide (EB)-fluorescence competitive method. The supercoiled DNA hydrolytic cleavage by 1,4-dioctyl-1,4-diazepan-6-ol (4) was supported by the evidence from free-radical quenching and T4-ligase ligation. Preliminary pharmacological tests showed that only 1,4-dioctyl-1,4-diazepan-6-ol (4) had antitumor activity against HeLa cell lines in vitro. [source] | |||||||||||||