OBJECTIVETo investigate the mechanism of increasing chemosensitivity of gallbladder carcinoma stimulated by somatostatin.

METHODSGBC-SD cells were divided into four groups: SST-alone-treated group, Doxorubicin (DOX)-alone-treated group and co-treated group (co-treatment of SST and DOX). In the control group, the cells were cultivated by medium only. In SST-alone-treated group, the cells were cultivated by medium with SST in the concentration of 75 microg/ml. In DOX-alone-treated group, the cells were cultivated by medium with DOX in the gradient concentrations of 5, 10, 20 microg/ml. In the co-treated group, cells were first cultivated by medium with 75 microg/ml SST for 24 h, followed by the addition of DOX in the gradient concentrations mentioned above. Cell viability curve was measured by MTT assay at 24, 48, 72 and 96 h, respectively. Meanwhile, the alterations of protein expressions of ICBP90 and Topo IIalpha after treatment of SST were examined by Western blot.

RESULTSThe treatment of SST alone on GBC-SD cells did not exert significantly inhibitory effect compared to the control group (P > 0.05). However, 24 h after the treatment of SST, the protein expressions of ICBP90 and Topo IIalpha were both up-regulated (P < 0.05).

CONCLUSIONUp-regulated the expression of ICBP90 by somatostatin maybe the cause of overexpression of Topo IIalpha, which leads to the enhanced lethal effect of DOX.

Antigens, Neoplasm ; metabolism ; Apoptosis ; drug effects ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; DNA Topoisomerases, Type II ; metabolism ; DNA-Binding Proteins ; metabolism ; Doxorubicin ; pharmacology ; Drug Interactions ; Drug Resistance, Neoplasm ; drug effects ; Gallbladder Neoplasms ; drug therapy ; metabolism ; pathology ; Humans ; Somatostatin ; pharmacology

OBJECTIVETo observe whether the Ginsenosides (GS) could induce HL-60 cell line apoptosis from promyelocytic leukemia.

METHODSHL-60 cells were treated with GS of various concentration to observe the effect of GS on cell morphological change, the DNA content change by flow cytometry, DNA ladder by electrophoresis, and apoptosis rate by Annexin V-FITC test of the cells.

RESULTSGS could inhibit the growth of HL-60 cells and induce cell apoptosis in a certain scope of dose and reacting time.

CONCLUSIONGS could specifically induce apoptosis in HL-60 cells, which provides an experimental basis for treatment of leukemia with GS as an supplemntary agent of chemotherapy.

Apoptosis ; drug effects ; Cell Division ; drug effects ; DNA, Neoplasm ; analysis ; Ginsenosides ; pharmacology ; HL-60 Cells ; pathology ; Humans

OBJECTIVETo clone differentially expressed cDNA sequences involved in malignant transformation induced by benzo(a)pyrene metabolite dihydroxyepoxy benzo pyrene (BPDE).

METHODThe malignant transformation of human bronchial epithelial cell line 16HBE induced by BPDE in vitro was used as a model for comparing gene expression between the transformed cells and controls. cDNA representational difference analysis (cDNA-RDA) was performed to isolate differentially expressed cDNA fragment in transformed cells. The cDNA fragments were ligated to pGEM-T vector and transformed into JM109 bacteria. The plasmid DNA were sequenced and compared with data in GenBank by BLASTN.

RESULTSFive cDNA sequences were found to be novel ones and were registered in dbest database, which assigned accession numbers in GenBank are BG354691, BG354692, BG354693, BG354694 and BG354695, respectively. Eight of the remaining cDNA sequences showed sequence homology to those previously reported such as ribosomal protein S23, MLN137, ACTN4, transforming growth factor and G protein gene.

CONCLUSIONSThese 13 genes may be involved in BPDE-induced malignant transformation, but their biological characteristics and functions are left to further studies.

Benzopyrenes ; metabolism ; pharmacology ; Carcinogens ; pharmacology ; Cell Transformation, Neoplastic ; chemically induced ; genetics ; Cells, Cultured ; Cloning, Molecular ; DNA, Complementary ; analysis ; drug effects ; DNA, Neoplasm ; analysis ; Gene Expression ; drug effects ; Humans

The present study was aimed to investigate the damage effect of hepatocyte growrh promoting substance (HGS) on the HL-60 cell DNA in vitro and to explore the possible mechanism underlying the effect. Experiment was divided into 3 groups: one was control group, in which 0.9% NaCl solution was added, and other two were experimental group 1 and group 2, where 22.5 microg/ml and 40 microg/ml HGS were added, respectively. HL-60 cell growths were compared between groups with and without HGS. Single cell gel electrophoresis (SCGE) was used to detect DNA damage of HL-60 cell. DNA electrophoresis was used to detect the apoptosis of HL-60 cells caused by HGS. The results showed that the inhibitory effects of HGS on growth of HL-60 cells were observed in group with 22.5 microg/ml and group with 40 microg/ml after culture for 2 days, the DNA ladder and the apoptosis of HL-60 cells occurred in these 2 groups on day 2 after addition of HGS, the counts of HL-60 cells with comet tail in these experimental groups were found to be more increased in comparison with control group. In conclusion, the HGS can inhibit the growth of HL-60 cell and the apoptosis of HL-60 cells should be induced through pathway of DNA damage caused by HGS.
Animals ; Animals, Newborn ; Apoptosis ; drug effects ; genetics ; Cattle ; Cell Proliferation ; drug effects ; Comet Assay ; DNA Damage ; DNA, Neoplasm ; analysis ; genetics ; HL-60 Cells ; Humans ; Peptides ; pharmacology

The occurrence and development of acute myeloid leukemia (AML) is not only related to gene mutations, but also influenced by abnormal epigenetic regulation, in which DNA methylation is one of the most important mechanisms. Abnormal DNA methylation may lead to the activation of oncogene and the inactivation of tumor suppressor gene, resulting in the occurrence of leukemia. The mutations of DNA methylation enzymes associated with AML may have certain characteristics. The AML with recurrent cytogenetic abnormalities is also related to abnormal methylation. Some fusion genes can alter DNA methylation status to participate in the pathogenesis of leukemia. In addition, chemotherapy drug resistance in patients with AML is associated with the change of gene methylation status. Considering the reversibility of the epigenetic modification, targeted methylation therapy has become a hotspot of AML research.
DNA Methylation ; drug effects ; genetics ; physiology ; DNA Modification Methylases ; genetics ; physiology ; Drug Resistance, Neoplasm ; genetics ; Epigenesis, Genetic ; genetics ; physiology ; Humans ; Leukemia, Myeloid, Acute ; etiology ; genetics ; pathology ; Mutation ; genetics

OBJECTIVETo study the effect and mechanism of tetrandrine (Tet) on enhancing radiosensitivity of human nasopharyngeal carcinoma cell lines in vitro.

METHODSCNE1 and CNE2 were exposed to radiation with or without Tet, the DNA damage of the cells were evaluated by neutral comet electrophoresis, and cell cycle and apoptosis were analyzed by flow cytometry.

RESULTSThe mean tail movements (TM) of CNE1 treated with radiation or radiation plus Tet were (7.13 ± 3.70) (X(-) ± s) and (13.61 ± 5.45), respectively (t = 2.784, P < 0.05), and TM of CNE2 treated with radiation or radiation plus Tet were (11.52 ± 4.04) and (18.85 ± 6.18), respectively (t = 3.089, P < 0.05). With the exposure to radiation or radiation plus Tet, the percentages of CNE1 in G2 phases were (42.62 ± 2.07)% and (17.02 ± 1.87)%, respectively (t = 23.173, P < 0.01), and the percentages of CNE2 in G2 phases were (34.82 ± 2.74)% and (19.64 ± 4.82)%, respectively(t = 16.500, P < 0.01). There was no significant difference in the apoptosis rates between the cells treated with radiation or radiation plus Tet regardless of CNE1 (17.24 ± 0.99)% vs (19.11 ± 1.24)%, and CNE2 (16.68 ± 0.27)% vs (18.51 ± 2.41)% (P > 0.05).

CONCLUSIONSTet can enhance radiosensitivity of human nasopharyngeal carcinoma cell lines. The mechanism could be related to abrogation of radiation-induced G2/M arrest and reduction of double-strand break repair capacity.

Apoptosis ; drug effects ; Benzylisoquinolines ; administration & dosage ; pharmacology ; toxicity ; Carcinoma ; Cell Line, Tumor ; DNA Repair ; Humans ; Nasopharyngeal Neoplasms ; Neoplasm Metastasis ; Radiation Tolerance ; drug effects

The purpose of this investigation was to study the variation of p73 gene expression in the apoptotic process of acute myeloid leukemia (AML) cell line U937 induced by methotrexate (MTX). Morphological changes of apoptotic cells were observed with microscopy and Wright's + Giemsa staining. DNA ladder and cell cycle were examined by agarose gel electrophoresis and flow cytometry respectively. Using semi-quantitive reverse transcription-polymerase chain reaction (RT-PCR), the expression of p73 mRNA was examined. Results showed that MTX could induce U937 cell apoptosis effectively. Condensed nuclei, fragmentation of chromosome and DNA ladder were seen after 6 hour following treatment of MTX 5 micro mol/L. Sub-G(1) peak and S + G(2)/M arrest were also determined by FCM, but the quantity of p73 expression was generally constant. In conclusion, U937 cell apoptosis induced by MTX did not change p73 mRNA level.
Acute Disease ; Antimetabolites, Antineoplastic ; pharmacology ; Apoptosis ; drug effects ; genetics ; Cell Cycle ; drug effects ; Cell Division ; drug effects ; DNA, Neoplasm ; drug effects ; genetics ; metabolism ; DNA-Binding Proteins ; genetics ; Flow Cytometry ; Gene Expression Regulation, Neoplastic ; drug effects ; Genes, Tumor Suppressor ; Humans ; Leukemia, Myeloid ; drug therapy ; genetics ; pathology ; Methotrexate ; pharmacology ; Nuclear Proteins ; genetics ; RNA, Messenger ; drug effects ; genetics ; metabolism ; Tumor Protein p73 ; Tumor Suppressor Proteins ; U937 Cells

In order to explore the differences between the mechanisms of selenite-induced apoptosis and arsenic induced apoptosis in NB4 cells, growth inhibition was determined by MTT test, apoptosis determined by DNA electrophoresis and analysis of intracellular DNA contents, reactive oxygen species and reduced glutathione in the cell were measured by Lucigenin dependent chemoluminescent (CL) test and spectrophotometry, and mitochondrial transmembrane potential was measured by flow cytometry. The results showed that: 5 micro mol/L sodium selenite similar to 1 micro mol/L arsenic trioxide could induce the apoptosis of NB4 cells after treatment for 24 hours. Both could elevate the level of reactive oxygen species and intensify mitochondrial transmembrane potential collapse, accompanied with decrease of reduced glutathione centent. The effect of selenium selenite on these aspects was more significant than those of arsenic trioxide. Elevation of intracellular glutathione in N-acytlcysteine pretreated NB4 cells could enhance the selenite induced apoptosis and oxidative stress, but ameliorate the arsenic trioxide induced apoptosis and oxidative stress. It was concluded that sodium selenite and arsenic trioxide can induce the apoptosis of NB4 cells, but there are significant differences between the mechanisms of selenite-induced and arsenic-induced apoptosis in NB4 cells, particularly in the influence of intracellular glutathione content on the drug action.
Acetylcysteine ; pharmacology ; Apoptosis ; drug effects ; genetics ; Arsenicals ; pharmacology ; Cell Division ; drug effects ; DNA, Neoplasm ; drug effects ; genetics ; metabolism ; Flow Cytometry ; Glutathione ; drug effects ; metabolism ; Humans ; Intracellular Membranes ; drug effects ; physiology ; Leukemia, Promyelocytic, Acute ; metabolism ; pathology ; Membrane Potentials ; drug effects ; Mitochondria ; drug effects ; physiology ; Oxides ; pharmacology ; Reactive Oxygen Species ; metabolism ; Sodium Selenite ; pharmacology ; Tumor Cells, Cultured ; drug effects

Traditional theories suggest that tumor growth occurs when all tumor cells work together and result in proliferation, so treatment has been mainly directed against the majority of the cells in tumor tissue, which often relapse, metastasize, and lead to treatment failure. As cancer stem cells have been successfully isolated from different tumor tissues, in-depth study of their function in relation to traditional cancer treatment faces enormous challenges. At the same time, a new theoretical basis has been provided for the in-depth study of tumorigenesis and the evaluation of prognosis of cancer therapy. Also, new ideas have been introduced for cancer therapy. Therefore, radical treatment of cancer can be achieved through killing cancer stem cells. This article reviews the research progress on cancer stem cells and their drug resistance.
ATP-Binding Cassette Transporters ; metabolism ; Animals ; Antineoplastic Agents ; pharmacology ; Apoptosis ; Cell Hypoxia ; Cell Transformation, Neoplastic ; DNA Repair ; DNA, Neoplasm ; genetics ; Drug Resistance, Multiple ; Drug Resistance, Neoplasm ; Humans ; Neoplasms ; genetics ; metabolism ; pathology ; Neoplastic Stem Cells ; drug effects ; pathology

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.
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 ; Human ; 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 effects