Subject(s)
Animals , Humans , Mice , Antineoplastic Agents/therapeutic use , Neoplasm Proteins/antagonists & inhibitors , Neoplasms/drug therapy , Poly(ADP-ribose) Polymerases/antagonists & inhibitors , Antineoplastic Agents/pharmacology , Clinical Trials as Topic , DNA Repair/drug effects , DNA, Neoplasm/drug effects , DNA, Neoplasm/metabolism , Dacarbazine/administration & dosage , Dacarbazine/analogs & derivatives , Dacarbazine/pharmacology , Drug Delivery Systems , Drug Design , Drug Resistance, Neoplasm , Drug Screening Assays, Antitumor , Drug Synergism , Mice, Knockout , Neoplasm Proteins/physiology , Neoplasms/enzymology , Poly(ADP-ribose) Polymerases/chemistry , Poly(ADP-ribose) Polymerases/deficiency , Poly(ADP-ribose) Polymerases/genetics , Poly(ADP-ribose) Polymerases/physiology , Radiation Tolerance/drug effectsABSTRACT
Numerous types of cells have been shown to undergo apoptosis when exposed to oxidant agent such as hydrogen peroxide. In order to understand the functional relationship between the anti- and pro-apoptotic regulatory proteins in the cells under oxidant stress, we have studied the level of expression of apoptosis regulatory proteins, bcl-2 and bax, in human leukemia HL-60 cells. The exposure of HL-60 cells to different concentrations of H2O2 for 6 h resulted in a typical apoptosis of the cells as characterized by flow cytometry, cell cycle analysis, and DNA fragmantation. There was a block in G1 to S transition and apoptotic cells were mainly derived from S and G2 cells. Kinetic study demonstrated that the levels of both bcl-2-mRNA and -protein expression were decreased with the progression of cellular apoptosis whereas the level of bax-mRNA was unchanged but the expressed bax-protein was not detectable. Cycloheximide, a nonspecific translation inhibitor, did not prevent the hydrogen peroxide-mediated apoptosis in HL-60 cells. These results suggest that the regulation of bcl-2, but not of bax are important factor in the oxidative stress-induced apoptosis in HL-60 cells.
Subject(s)
Humans , Apoptosis/drug effects , Blotting, Western , Cycloheximide/pharmacology , DNA Fragmentation , DNA, Neoplasm/metabolism , DNA, Neoplasm/genetics , DNA, Neoplasm/drug effects , Dose-Response Relationship, Drug , Flow Cytometry , Gene Expression Regulation, Neoplastic/drug effects , HL-60 Cells , Hydrogen Peroxide/pharmacology , Oxidants/pharmacology , Protein Synthesis Inhibitors/pharmacology , Proto-Oncogene Proteins/metabolism , Proto-Oncogene Proteins/genetics , Proto-Oncogene Proteins c-bcl-2/metabolism , Proto-Oncogene Proteins c-bcl-2/genetics , RNA, Messenger/metabolism , RNA, Messenger/genetics , RNA, Messenger/drug effectsABSTRACT
Limited digestion (2 min) of Sarcoma-180 nuclei by DNase-II released two nonhistone proteins from the hypersensitive sites of chromatin. The apparent molecular weights of these two proteins were 34 and 21 kDa. These proteins showed a moderate but specific inhibition in in vitro cell free transcription assay with native chromatin as template as opposed to no effect on native DNA transcription.
Subject(s)
Animals , Chromatin/metabolism , DNA, Neoplasm/metabolism , DNA-Binding Proteins/isolation & purification , Endodeoxyribonucleases/metabolism , Male , Mice , Rats , Sarcoma 180/genetics , Transcription, Genetic/physiologyABSTRACT
The cytotoxic effects of acetylated oil of Semecarpus anacardium nuts on the cells of P388 lymphocytic leukemia were tested in vitro. The product was tested at the concentrations ranging from 15-75 micrograms/ml. The cell kill was observed as early as three hr after the treatment. The effects of acetylated oil on the biosynthesis of DNA, RNA and protein using labelled thymidine, uridine and leucine respectively showed that the product inhibited the biosynthesis of all the three. This was indicated by the inhibition of the incorporation of their precursors. The uptake of 3H-thymidine was inhibited 15 min after treatment; while that of 3H-uridine and 14C-leucine took 30 and 45 min respectively. Since the S. anacardium oil was unstable due to air-oxidation, the studies were confined to its acetylated product.