DNA repair processes play a role in the development of drug resistance which represents a huge obstacle to leukemia chemotherapy. Histone H2AX phosphorylation （ser139） （γH2AX） occurs rapidly at the onset of DNA d...DNA repair processes play a role in the development of drug resistance which represents a huge obstacle to leukemia chemotherapy. Histone H2AX phosphorylation （ser139） （γH2AX） occurs rapidly at the onset of DNA double strand break （DSB） and is critical to the regulation of DSB repair. If DNA repair is successful, cells exposed to anti-neoplastic drugs will keep entering the cycle and develop resistance to the drugs. In this study, we investigated whether γH2AX can be used as an indicator of tumor chemosensitivity and a potential target for enhancing chemotherapy. K562 and multi-drug resistant cell line K562/A02 were exposed to adriamycin （ADR） and γH2AX formed. Flow cytometry revealed that percentage of cells expressing γH2AX was increased in a dose-dependent manner and the percentage of K562/A02 cells was lower than that of K562 cells when treated with the same concentration of ADR. In order to test the potential of γH2AX to reverse drug resistance, K562/A02 cells were treated with PI3K inhibitor LY294002. It was found that LY249002 decreased ADR-induced γH2AX expression and increased the sensitivity of K562/A02 cells to ADR. Additionally, the single-cell gel electrophoresis assay and the Western blotting showed that LY249002 enhanced DSBs and decreased the expression of repair factor BRCA1. These results illustrate chemosensitivity can partly be measured by detecting γH2AX and drug resistance can be reversed by inhibiting γH2AX.展开更多
OBJECTIVE To investigate the effects of survivin antisense oligodeoxy-nucleotid (ASODN) on proliferation and apoptosis in the chronic myeloid leukemia cell line K562. METHODS Different concentrations of an antisense o...OBJECTIVE To investigate the effects of survivin antisense oligodeoxy-nucleotid (ASODN) on proliferation and apoptosis in the chronic myeloid leukemia cell line K562. METHODS Different concentrations of an antisense oligodeoxy-nucleotid and control sequence (scrambled ODN) targeting the survivin gene were transferred into K562 by a lipofectin reagent. The MTT assay was used to measure the growth inhibitory rate, IC50, and to observe the cytotoxicity of survivin ASODN in the K562 cells. The morphologic changes in the nucleus and the apoptotic rate were observed by Hoechst33342/PI staining. Caspase-3 activity was evaluated by a kinase activity assay. The changes of survivin protein expression after transfection were detected by Western blots. RESULTS Eight hours after transfection, fluorescence in the K562 cells was well distributed. Treatment of the cells for 44 h with different concentrations of survivin ASODN produced a IC50 of 800 nmol/L. The growth inhibitory rate with 200, 400, 600 and 1000 nmol/L of survivin ASODN was 15.8±1.6%, 23.8±5.9%, 37.1±5.6% and 77.3±2.5% respectively. After 36 h of of survivin ASODN treatment, distinct morphologic changes characteristic of cell apoptosis such as karyopyknosis and conglomeration were observed by Hoechst33342/PI staining. Caspase-3 activity increased significantly after treatment of the cells with different concentrations of survivin ASODN(P<0.01)and following treatment with 800 nmol/L survivin ASODN, survivin expression decreased significantly. CONCLUSION Survivin ASODN exerts an anti-cancer effect by inducing apoptosis in K562 leukaemia cells. Up-regulated expression of caspase-3 may play a role in this process.展开更多
It is first demonstrated that dipyridamole (DP) and radiation were capable of significantly inhibiting, independently and synerglcally, clonogenlc growth in the two kinds of K562 cell lines, adriamycin (ADM) -sensitiv...It is first demonstrated that dipyridamole (DP) and radiation were capable of significantly inhibiting, independently and synerglcally, clonogenlc growth in the two kinds of K562 cell lines, adriamycin (ADM) -sensitive and ADM- resistant. DP or radiation alone Increased clonogenlc Inhibition rate (CIR) in the two kinds of cell lines in a dose- dependent fashion. DP potentiated radiosensitivity and radiation increased inhibition of DP in the two kinds of cell lines. K562/ ADM cell lines were higher sensitive to DP. radiation and combination of them than K562 cell lines (P<0. 01). There was stronger synergic inhibition of clonogenlc growth in the two kinds of cell lines when pretreated with DP than when posttreated with DP (P<0. 01).展开更多
It was first reported here that verupamil(VP) and electric beam radiation(EBR) were capable of inhibiting,independently or synergically,clonogenic growth in two kinds of K562 cell lines, adriamycin(ADM)-sensitive and ...It was first reported here that verupamil(VP) and electric beam radiation(EBR) were capable of inhibiting,independently or synergically,clonogenic growth in two kinds of K562 cell lines, adriamycin(ADM)-sensitive and ADM-resistant(K562/S and K562/ADM).Results showed that clonogenic rate(CGR) decreased by 3%-99.9% in the prasence of dependent dose-ADM(3.8μg/ml) in K562/ADM cell lines,while treated with 0.5μM-6μM of VP.VP was capable of potentiating radiosensitivity in K562/S and K562/ADM cell lines,whether before or after exposure of them to electric beam radiation,and significantly reduced CGR in these kinds of cell lines(P<0.01).展开更多
基金supported by a grant from the National Key Technology R&D Program (No. 30270727)
文摘DNA repair processes play a role in the development of drug resistance which represents a huge obstacle to leukemia chemotherapy. Histone H2AX phosphorylation （ser139） （γH2AX） occurs rapidly at the onset of DNA double strand break （DSB） and is critical to the regulation of DSB repair. If DNA repair is successful, cells exposed to anti-neoplastic drugs will keep entering the cycle and develop resistance to the drugs. In this study, we investigated whether γH2AX can be used as an indicator of tumor chemosensitivity and a potential target for enhancing chemotherapy. K562 and multi-drug resistant cell line K562/A02 were exposed to adriamycin （ADR） and γH2AX formed. Flow cytometry revealed that percentage of cells expressing γH2AX was increased in a dose-dependent manner and the percentage of K562/A02 cells was lower than that of K562 cells when treated with the same concentration of ADR. In order to test the potential of γH2AX to reverse drug resistance, K562/A02 cells were treated with PI3K inhibitor LY294002. It was found that LY249002 decreased ADR-induced γH2AX expression and increased the sensitivity of K562/A02 cells to ADR. Additionally, the single-cell gel electrophoresis assay and the Western blotting showed that LY249002 enhanced DSBs and decreased the expression of repair factor BRCA1. These results illustrate chemosensitivity can partly be measured by detecting γH2AX and drug resistance can be reversed by inhibiting γH2AX.
文摘OBJECTIVE To investigate the effects of survivin antisense oligodeoxy-nucleotid (ASODN) on proliferation and apoptosis in the chronic myeloid leukemia cell line K562. METHODS Different concentrations of an antisense oligodeoxy-nucleotid and control sequence (scrambled ODN) targeting the survivin gene were transferred into K562 by a lipofectin reagent. The MTT assay was used to measure the growth inhibitory rate, IC50, and to observe the cytotoxicity of survivin ASODN in the K562 cells. The morphologic changes in the nucleus and the apoptotic rate were observed by Hoechst33342/PI staining. Caspase-3 activity was evaluated by a kinase activity assay. The changes of survivin protein expression after transfection were detected by Western blots. RESULTS Eight hours after transfection, fluorescence in the K562 cells was well distributed. Treatment of the cells for 44 h with different concentrations of survivin ASODN produced a IC50 of 800 nmol/L. The growth inhibitory rate with 200, 400, 600 and 1000 nmol/L of survivin ASODN was 15.8±1.6%, 23.8±5.9%, 37.1±5.6% and 77.3±2.5% respectively. After 36 h of of survivin ASODN treatment, distinct morphologic changes characteristic of cell apoptosis such as karyopyknosis and conglomeration were observed by Hoechst33342/PI staining. Caspase-3 activity increased significantly after treatment of the cells with different concentrations of survivin ASODN(P<0.01)and following treatment with 800 nmol/L survivin ASODN, survivin expression decreased significantly. CONCLUSION Survivin ASODN exerts an anti-cancer effect by inducing apoptosis in K562 leukaemia cells. Up-regulated expression of caspase-3 may play a role in this process.
文摘It is first demonstrated that dipyridamole (DP) and radiation were capable of significantly inhibiting, independently and synerglcally, clonogenlc growth in the two kinds of K562 cell lines, adriamycin (ADM) -sensitive and ADM- resistant. DP or radiation alone Increased clonogenlc Inhibition rate (CIR) in the two kinds of cell lines in a dose- dependent fashion. DP potentiated radiosensitivity and radiation increased inhibition of DP in the two kinds of cell lines. K562/ ADM cell lines were higher sensitive to DP. radiation and combination of them than K562 cell lines (P<0. 01). There was stronger synergic inhibition of clonogenlc growth in the two kinds of cell lines when pretreated with DP than when posttreated with DP (P<0. 01).
文摘It was first reported here that verupamil(VP) and electric beam radiation(EBR) were capable of inhibiting,independently or synergically,clonogenic growth in two kinds of K562 cell lines, adriamycin(ADM)-sensitive and ADM-resistant(K562/S and K562/ADM).Results showed that clonogenic rate(CGR) decreased by 3%-99.9% in the prasence of dependent dose-ADM(3.8μg/ml) in K562/ADM cell lines,while treated with 0.5μM-6μM of VP.VP was capable of potentiating radiosensitivity in K562/S and K562/ADM cell lines,whether before or after exposure of them to electric beam radiation,and significantly reduced CGR in these kinds of cell lines(P<0.01).
