Search

Objective: To investigate the inhibitory effect of arsenic trioxide (As₂O₃) combined with tetradecanoylphorbol acetate (TPA) on the proliferation of Kasumi-1 cell line and its mechanism., Methods: Kasumi-1 cells were treated with 200 nmol/L TPA, different concentrations of As₂O₃ alone and combined with 200 nmol/L TPA. The proliferative inhibition rates were determined with CCK-8. Annexin V was adopted to detect apoptosis. Colony formation assay was used to determine the cloning efficiency. Flow cytometry was used to detect the cell differentiation and cell cycle changes. Western blot was employed to detect the expression of P38 and p-P38., Results: The proliferation inhibition rates of Kasumi-1 cells by TPA combined with different concentrations of As₂O₃ (0.2, 2.0 and 20.0 mmol/L)for 48 h were (25.56 ± 7.29)%, (60.63 ± 6.64)%, and (73.37 ± 2.15)%, the apoptosis rates were (61.65 ± 2.62)%, (75.39 ± 1.04)%, and (89.95 ± 1.46)%, and the colony formation rates were (76.17 ± 2.06)%, (38.50 ± 1.87)%, and (18.53 ± 2.20)%, respectively, compared with the different concentrations of As₂O₃ alone groups, the difference was statistically significant (P<0.05). Cells treated with both TPA and As₂O₃ expressed more CD11b antigens compared with the cells exposed to As₂O₃ alone. TPA treated Kasumi-1 cells were arrested at G1 phase compared with the control group, while As₂O₃ increased the percentage of Kasumi-1 cells in the G2 phase. Combination treatment increased the expression of p-P38 of Kasumi-1 cells compared with the cells exposed to As₂O₃ alone., Conclusion: TPA can enhance the effect of As₂O₃ on inducing apoptosis and regulating cell cycle, thereby enhancing its anti-leukemia effect.

Objective: To detect the methylation status of TMS1 gene and its demethylation by arsenic trioxide (As₂O₃) in K562 cells., Methods: K562 cells were treated with different concentrations of As₂O₃ for 48 hours. Methylation-specific PCR (MSP) was used to determine the methylation status of TMS1. RT-PCR and Western blot were used to detect the levels of TMS1 mRNA and protein. TMS1 associated apoptosis proteins Bcl-2/Bax were also analyzed by Western blot. Apoptosis were evaluated by flow cytometry using Annexin V/propium iodide (PI) double staining., Results: TMS1 gene was completely methylated in K562 cells and the levels of TMS1 mRNA and protein were low (0.01±0.01, 0.09±0.02), which could be reversed (mRNA: 0.72±0.04; protein: 1.30±0.06; P<0.01) by 2 μmol/L As2O3 via overt demethylation of TMS1 gene. Apoptosis in experiment group (12.24±1.06) was significantly higher than that in control group (2.05±0.16, P<0.05). In experiment group, the down-expression of antiapoptotic protein Bcl-2 and up-expression of pro-apoptotic protein Bax led to an obvious decline ratio of Bcl-2/Bax (0.56±0.12), as compared to the control group (1.94±0.14, P<0.01)., Conclusion: As₂O₃ could up-regulate TMS1 gene expression by reversing its hypermethylation and induced apoptosis by down-regulation of Bcl-2/Bax ratio in K562 cells.

Objective: To study the effect of transforming growth factor-β activated kinase-1 (TAK1) gene silencing on the proliferation and apoptosis of Kasumi-1 cells induced by arsenic trioxide (As₂O₃)., Methods: Acute myeloid leukemia with t(8;21) cell line Kasumi-1 cells were treated with As₂O₃ or in combination with TAK1 siRNA interference technology. The experiment was divided into four groups: Kasumi-1 cells without any treatment, TAK1 specific siRNA transfection alone, Kasumi-1 cells treated with different concentration of As₂O₃, TAK1siRNA transfection combined with As₂O₃. CCK-8 was used to detect the cell viability. The expression of phosphorylated c-Jun N-terminal kinase (P-JNK) was determined by Western Blot. Cell apoptosis and growth were examined by morphological and colony formation assay., Results: After Kasumi-1 cells were treated with As₂O₃, the rate of cell inhibition was concentration-dependent, and the 50% inhibitory concentration was 3.5 μmol/L. The highest expression level of P-JNK appeared in 30 minutes after cells were treated with As₂O₃. The apoptosis rates of Kasumi-1 cells without any treatment, TAK1 siRNA interference alone group, As₂O₃ alone group and the combined group were (5.02 ± 1.13)%, (6.18 ± 0.28)%, (48.33 ± 2.70)% and (86.07 ± 2.21)%; colony formation rates were (73.83 ± 2.78)%, (76.03 ± 1.46)%, (55.07 ± 1.50)% and (22.20 ± 1.15)%; apoptosis rate of TAK1 siRNA group and the untreated group has no significant difference (P = 0.052); colony formation rate between TAk1 siRNA group and the untreated group has no significant difference (P = 0.179), but the difference in other groups was significant (P = 0.000)., Conclusion: Silencing the expression of TAK1 can enhance the anti-proliferative and pro-apoptotic effect of As₂O₃ on Kasumi-1 cells, and its mechanism may be through the TAK1 downstream JNK signal pathway.

Objective: To study the expression profile of microRNAs in acute promyelocytic leukemia (APL) cells during differentiation., Methods: Differentiation of APL cell line NB4 cells was induced by all-trans retinoic acid (ATRA) and arsenic trioxide (As2O3). Morphological and immunological assay was performed by Wright-Giemsa staining and flow-cytometric analysis of CD11b surface expression. During in vitro NB4 differentiation induced by ATRA and As2O3, microRNA expression profiles (miR-15b, miR-16, miR-34a, miR-107, miR-124a, miR-146, miR-155, miR-181a, miR-223, miR-342, let7c) were detected by real time RT-PCR, and the relative expression level of microRNAs were quantitatively analyzed by using 2(-ΔΔCt), and compared with that of control group. Meanwhile, the microRNA expression profiles were also detected in 15 newly diagnosed APL patients and 15 complete remission (CR) APL cases by real time RT-PCR, and the relative expression level of microRNA was quantitated by using 2(-ΔCt), and compared with that of control group (newly diagnosed APL as control group). These data were expressed as x(-) ± s, and differences between groups were examined using t test. P < 0.05 was considered statistically significant., Results: The expression levels of miR-15b, miR-16, miR-107, miR-223 and miR-342 in NB4 differentiation group were obviously up-regulated (3.40, 4.22, 5.41, 20.03 and 5.29 folds higher in ATRA treated NB4 cells than that of control group respectively, and 3.62, 2.49, 2.58, 4.27 and 1.94 folds higher in AS2O3 treated NB4 cells than that of control group respectively), except for miR-15b, the expression levels of miR-16, miR-107, miR-223 and miR-342 in ATRA treated group was significantly higher than that in As2O3 treated group. The relative expression levels of miR-15b, miR-16, miR-107, miR-181a, miR-223 and miR-342 were 0.4137, 0.6367, 0.1260, 0.0522, 0.6611, 0.0280 in APL CR group, and 0.0751, 0.2022, 0.0425, 0.3064, 0.1733, 0.0090 in newly diagnosed APL group, respectively. The expression level of miR-15b, miR-16, miR-107, miR-223 and miR-342 in APL CR group were significantly upregulated compared with that of newly diagnosed APL groups (P < 0.05), while the expression level of miR-181a was significantly downregulated (P < 0.05)., Conclusion: Specific expression of microRNA profiles is a key contributing factor in the differentiation of APL.

Objective: To investigate the effect of deferoxamine (DFO) and DFO in combination with arsenic trioxide (ATO) on inhibition of HL-60 cells xenograft tumor growth in nude mice and its mechanism., Methods: Xenograft tumor model of HL-60 cell line in nude mice was established by inoculating HL-60 cells subcutaneously into nude mice. The tumor-bearing mice were randomly divided into four groups: 50 mg/kg DFO group (group I), 3 mg/kg ATO group (group II), combination group (50 mg/kg DFO + 1.5 mg/kg ATO (group III) and normal saline control group. The drugs were administered intraperitoneally from the day of inoculation (once a day for 10 days). The inhibitory effects on the tumor growth were compared. NF-κBp65 expression levels of the tumors were detected by immunohistochemistry (24h after the last administration)., Results: (1) Tumors growth could be observed in all of the nude mice on day 7 to day 8 after inoculation, 0.5 - 1.0 cm in diameter, and then grew rapidly; (2) Tumor weight of control group, group I, group II and group III were (2.62 ± 0.54) g, (2.55 ± 0.82) g, (2.34 ± 0.79) g and (1.95 ± 0.39) g respectively, and the growth inhibition rates in group I, group II and group III were 2.67%, 10.69% and 25.57% respectively. Both DFO alone and in combination with ATO could inhibit the growth of transplanted tumors, and the combination group exhibited more effects, with no vital organ damages in the tumor-bearing mice. (3) There was significant difference in mean value of NF-κBp65 expression among the three experimental groups (P < 0.05), with a descending order of control group > group II, > group I > group III., Conclusion: (1) Both DFO and ATO have antitumor activities on tumor-bearing mice, and their combination has an obvious and significant effect. (2) DFO combined with ATO, is well tolerated with no significant adverse effects in the nude mice. (3) Both DFO and ATO can downregulate NF-κBp65 expression of transplanted tumors, especially for their combination.

Objective: To explore the molecular mechanisms of arsenic trioxide (As2O3) inhibiting NB4 cells proliferation., Methods: The Janus kinase 1 (JAK1) protein level and its phosphorylation level in NB4 cells was detected by Western blots. NB4 cells were transfected with JAK1 siRNA or JAK1 plasmid to make JAK1 gene silenced or overexpressed. The inhibition of NB4 cells proliferation was measured by MTT assay and Trypan blue exclusion respectively. The variation of phosphorylation level of JAK1 and the cell cycle inhibitor P21 were determined by Western blots., Results: JAK1 protein was expressed stably in NB4 cells, with no phosphorylation. The phosphorylation of JAK1 was enhanced after the NB4 cells treated with As2O3. After NB4 cells transfected with JAK1 siRNA, the expression level of JAK1 was obviously lower than that of in the non-specific siRNA group and blank control group. The effect of As2O3 inhibiting NB4 cells proliferation was weaker in the JAK1 siRNA transfected group. The inhibiting rate of 4 micromol/L As2O3 on NB4 cells proliferation of JAK1 siRNA group was 49.12% being lower than that of the non-specific siRNA group (74.58%) and control group (72.33%). After NB4 cells transfected with JAK1 plasmid, the JAK1 expression level in wild-type and mutant type plasmid groups were significantly higher than those in the empty plasmid group, moreover the effect of As2O3 inhibiting proliferation was stronger in wild-type plasmid group. The inhibiting rate of 4 micromol/L As2O3 on NB4 cells proliferation of wild-type plasmid group was 69.53% being higher than that of the mutant type JAK1 plasmid group (37.26%) and the empty plasmid group (39.61%). The expression level of P21 was up-regulated after the NB4 cells treated with As2O3., Conclusion: JAK1 is expressed stably in NB4 cells, but has no activity. Arsenic trioxide inhibits the proliferation of NB4 cells through activating the JAK1. P21 is up-regulated after arsenic trioxide activated the JAK1 to inhibit the proliferation of NB4 cells.

Objective: To explore the effect of arsenic trioxide (As2O3) on the growth inhibition of imatinib (IM)-resistant bcr-abl mutant cell lines in vitro., Methods: Cell growth of one IM-sensitive cell line, 32Dp210 and 15 IM-resistant cell lines including T315I and other 14 bcr-abl mutants were detected by MTT assay after treatment with IM and As2O3. The cell lines with 5 frequently observed mutants in CML patients were analyzed for apoptosis by flow cytometry with Annexin V and PI staining as well as the expression of bcr-abl fusion protein, phosphorylated CRKL protein and apoptosis-related proteins by Western blot., Results: The fifty percent inhibition concentration (IC50) values of As2O3 for 15 IM-resistant cell lines were 2.6-5.3 fold lower than that for IM-sensitive cell line. For the 5 bcr-abl mutants frequently happened in CML patients, As2O3 significantly inhibited the expression of bcr-abl fusion protein and phosphorylated CRKL and induced apoptosis in a dose-dependent manner as compared with that for 32Dp210. Coincidently, the cell apoptosis was induced through caspase-3, 8 and 9 pathways., Conclusion: As2O3 remarkably inhibits cell growth and induces apoptosis of IM-resistant bcr-abl mutant cell lines in vitro, suggesting that it might be a potential therapeutic agent for IM-resistant CML patients.

Objective: To investigate the effect of bortezomib alone or combined with harringtonine (HT) or arsenic trioxide (As2O3) on the proliferation capacity and apoptosis of HL-60/ADM cell line and fresh cells from refractory/relapse acute leukemia patients., Methods: HL-60/ADM cells or refractory/relapse leukemia cells were incubated with bortezomib at different doses alone and in combination with HT or As2O3. The proliferation capacity was observed by MTT assay, cell apoptosis by fluorescence microscopy and flow cytometry. Intracellular concentration of daunorubicin (DNR) was determined by flow cytometry., Results: In bortezomib-treated HL-60/ADM cells, the proliferation inhibition rate and apoptotic cells increased in a time- and dose-dependent manner. 40 nmol/L bortezomib could maximally inhibit the proliferation of HL-60/ADM cells at 48 hours. 15 micromol/L As2O3 or 752 nmol/L HT combined with different doses of bortezomib could inhibit proliferation and induce apoptosis of HL-60/ADM cells. The As2O3 plus bortezomib or HT plus bortezomib showed a greater anticancer efficacy than either of the drugs alone (P < 0.05, P < 0.01). Bortezomib (10 nmol/L) could markedly enhance the intracellular accumulation of DNR in HL-60/ADM cells (P < 0.05)., Conclusions: Bortezomib can inhibit proliferation and induce apoptosis of HL-60/ADM cells and fresh refractory/relapse acute leukemia cells, especially combined with HT or As2O3.

Objective: To investigate the apoptosis-induction, P-glycoprotein (P-gp) and mdr1 mRNA inhibition effects of arsenic trioxide (As2O3) and buthionine sulfoximine (BSO) on multidrug-resistant cell line K562/ADM cells, and to determine the relationship between intracellular GSH content and arsenic effect., Methods: K562/ADM cells were treated with arsenic (0.5, 2.0, 5.0 micromol/L) alone or combined with BSO (100 micromol/L). The cell proliferating capacity was assessed with MTT assay, and cell apoptosis by Annexin V and propidium iodide (PI) staining. Intracellular GSH contents were measured using a glutathione assay kit by spectrophotometry. P-gp expression was determined by flow cytometry, and mdr1 mRNA expression by semi-quantitative RT-PCR., Results: The GSH contents in K562/ADM cell was (81.13 +/- 3.91) mg/g protein. After the GSH contents were degraded by BSO, the K562/ADM cell proliferating capacity was obviously inhibited and the cells were induced apoptosis in 24 hours by the combination of clinic dose arsenic group (0.5, 2.0 micromol/L) and BSO (100 micromol/L). The cell apoptosis rates at 48 hours in arsenic alone group and combination group were (59.29 +/- 6.01)% and (65.06 +/- 8.29)%, and at 72 hours were (82.15 +/- 9.28)% and (92.72 +/- 9.41)% retrospectively. At 48 hours, the mdr1 mRNA inhibition effect of the combination group was obviously stronger than that of high dose arsenic alone group. At 72 hours, the P-gp inhibition effect of the combination group (clinic dose arsenic group, 0.5, 2.0 micromol/L) was obviously stronger than that of high dose arsenic alone group (5.0 micromol/L)., Conclusion: The intracellular GSH contents are closely correlated with the arsenic effect. The combination of conventional dose arsenic and BSO significantly induces K562/ADM cell apoptosis and inhibits P-gp and mdr1 mRNA expression in the cells.

Objective: To explore the effect of arsenic trioxide (As2 O3) on the level of VEGF, VEGFR and the activity of MMP-2, 9 in K562 cells., Methods: The inhibition ratio of K562 cell was detected by MTT assay, the level of VEGF by Enzyme-linked immunosorbent assay (ELISA), the expression ratio of VEGFR by flow cytometry (FCM), and the activity of MMP-2, 9 by gelatin zymography assay., Results: (1) The IC50 of K562 cells was (2.12 +/- 0.11) micromol/L. Proliferation of K562 cells was significantly inhibited at the concentration of 0.4 - 6.4 micromol/L As2 O3 (P < 0.05). (2) The expression of VEGF was slightly up-regulated by 0.05 micromol/L As2 O3 (P > 0.05) and prominently inhibited by 0.4 micromol/L and 3.2 micromol/L As2 O3 (P < 0.05). As2 O3 had no influence on VEGFR. (3) The activity of MMP-2 and 9 was partly inhibited by 0.05 micromol/L As2 O3 incubated 72 hours and by 0.4, 3.2 micromol/L, As2 O3. With the increase of As2 O3 concentration and the incubation time, the inhibited effect on MMP-2 and 9 was enhanced., Conclusions: As2 O3 may down-regulate the expression of VEGF and inhibit the activity of MMP-2 and 9.

Objective: To explore the effect of 2-methoxyestradiol (2ME2) and arsenic trioxide (As2O3) on the apoptosis related gene expression in multiple myeloma cell line CZ-1., Methods: Total RNA was isolated from CZ-1 cells which had been treated with 2ME2 and As2O3 at an apoptosis-inducing concentration and reverse-transcribed into a cDNA probe labeled with Bio-16-dUTP, and then hybridized it with a microarray containing up to 96 key genes involved in apoptosis. The gene expression profile of the 2ME2 and As2O3 treated CZ-1 cells were analyzed with GEArray Analyzer software. The microarray results were confirmed by RT-PCR., Results: As2O3 treatment caused the alteration in the expression of 52 genes (54.2% of total genes on microarray). Among them, 42 (80.8%) were upregulated and 10 (19.2%) were downregulated. The upregulated genes were mainly involved in caspases family, P53 and ATM pathway, death effector domain family, TNF receptor family and CIDE family. 2ME2 treatment resulted in the alteration of 42 genes (43.8% of the total genes on microarray). Of them, 32 (76.2%) were downregulated and 10 (23.8%) were upregulated. The downregulated genes mainly belonged to bcl-2 family, inhibitor of apoptosis protein family (IAP), TRAF family, TNF ligand family, and CARD family., Conclusion: 2ME2 and As2O3 induce the CZ-1 cells apoptosis by different pathways. As2O3 mainly induces upregulation of proapoptotic genes, and 2ME2 downregulation of anti-apoptotic genes expression.

Objectives: To study the effect of dexamethasone (Dex) on the apoptosis and NF-kappaB activation in Raji cells as well as expression of MMP9 and VEGF induced by As2O3, and to observe the effect of inhibited activity of NF-kappaB by Dex on apoptosis., Methods: Cell apoptosis was analysed by Annexin V. Fluctuation of NF-kappaB, MMP9 and VEGF was detected by semi-quantitative immunohistochemistry., Results: The apoptosis and activation of NF-kappaB of Raji cells could be induced by As2O3. The percentage of apoptosis was (39.2 +/- 1.3)%. Dex significantly increased (77.5%) the apoptosis induced by As2O3 (P < 0.05). Dex suppressed the activation of NF-kappaB induced by As2O3 (a suppression rate of 28.0%, P < 0.05). There was a positive correlation between the changes of MMP9, VEGF and NF-kappaB., Conclusions: As2O3 could induce apoptosis, activate NF-kappaB and up-regulate expression of MMP9 and VEGF of Raji cells. The mechanism of enhanced apoptosis by Dex may be related to suppressing activation of NF-kappaB and down-regulating expression of MMP9 and VEGF.

Objective: To investigate the effect of arsenic trioxide on multiple myeloma (MM) cell gene expression and explore the molecular mechanism of arsenic trioxide therapy for MM., Methods: U266 cells were divided into two groups, group A as control group and group B as test group. Cells were cultured for 48 hours, and total RNA and mRNA were extracted. Suppression subtractive hybridization (SSHs) was performed to distinguish the differentially expressed genes. The products were cloned into pGEM-T Easy Vector, and transfected into the competent host JM109 to construct two subtractive libraries. Positive colonies were selected by blue-white screening, and the plasmids were extracted. Homologous comparison was conducted in GenBank., Results: Five downregulated clones were isolated in the first SSH: (1) Aminopeptidase N, (2) Homosapiens tumor translationally-controlled protein 1, (3) Human ATP synthetase A chain, (4) Signal recognition particle A10, (5) Mitochondrial ATP synthetase/ATPase subunit 6. Four upregulated clones were isolated in the second SSH: (1) Calcium-binding protein A10, (2) Keratin 6A, (3) 45 kD MIP repetitive element containing splicing factor and (4) poly(A)-binding protein., Conclusions: Arsenic trioxide exerts proliferation inhibition and apoptosis induction on MM cells by regulating genes expression.

Objective: To investigate the biological changes in myelodysplastic syndromes (MDS) myeloid blast cell line MDS-L after different duration and concentration of As2O3/TRAIL (TNF related apoptosis inducing ligand) treatment., Methods: MDS-L cells were treated with As2O3 and TRAIL at 9 different concentrations and the treated cells were detected at 24 h, 48 h and 72 h for biologic indexes. The same detections were conducted in untreated MDS-L cells and normal and MDS marrow cells as controls. Apoptosis was assayed by flow cytometry after Annexin V-FITC labelling. Differentiation-induction effect of these drugs on the cells were detected by morphologic examination and CD34(+) proportion analysis after 24 hours treatment and further agar culture for 18 days; P15(ink4b) mRNA expression were detected by RT-PCR and its protein expression by DAB immunocytochemistry, P15(ink4b) DNA methylation by methylation specific PCR (Msp)., Results: As2O3/TRAIL treatment promoted MDS-L cells to undergo apoptosis and As2O3 plus TRAIL showed obvious differentiation-induction effect on MDS-L. P15(ink4b) mRNA expression was upregulated in MDS-L cell line after different drug treatment but almost no protein expression increased. Increased P15 expression seemed to be related with DNA demethylation effect of these drugs., Conclusions: As2O3 or/and TRAIL treatment could promote apoptosis of the clonal cells and induce incomplete cell differentiation. The drugs treatment could also increase P15(ink4b) expression in MDS-L cell line through their demethylation effects.

Objective: To investigate the effects of protein tyrosine kinase (PTK), protein tyrosine phosphatase (PTP) and protein kinase C (PKC) on apoptosis and observe the changes of cytosolic calcium ([Ca(2+)]i) of arsenic trioxide (As2O3) treated human leukemia cells NB4 and cortex neurons., Methods: [Ca(2+)]i of NB4 cells and cortex neurons was probed with Fluo-3/AM, its changes were assayed with laser confocal microscopy in real-time after As2O3 treatment at different concentrations, the effects of PTK and PTP and the activation of PKC on these changes with confocal microscopy and phosphorus radioisotope assay. DNA ladders of NB4 cells and cortex neurons after exposed to As2O3 were observed., Results: As2O3 at 1 micromol/L could remarkably increase the [Ca(2+)]i of NB4 cells but had no effects on neurons. Vanadate, a kind of PTP inhibitor, could promote the increase of [Ca(2+)]i treated by 2, 5, 10 micromol/L As2O3 in a dose-dependent manner. The mean total increase rates at 240 seconds after exposed to As2O3 at different concentrations were (6.5 +/- 2.3)%, (21.7 +/- 2.1)%, (49.2 +/- 2.5)% for NB4 cells, and (6.7 +/- 2.1)%, (19.4 +/- 2.5)%, (52.3 +/- 2.7)% for cortex neurons, respectively. Genistein, a kind of PTK inhibitor, could decrease the increase of [Ca(2+)]i treated by 2, 5, 10 micromol/L As2O3 in a dose-dependent manner. The mean total inhibited rates at 240 seconds after As2O3 treatment at different concentrations were (6.7 +/- 2.9)%, (25.6 +/- 2.5)%, (52.2 +/- 3.5)% for NB4 cells, and (7.8 +/- 3.1)%, (18.1 +/- 2.8)%, (51.3 +/- 3.3)% for cortex neurons, respectively. The activation of PKC began to increase as exposed to As2O3 at 1 micromol/L for 3 h, and kept rising continuously in NB4 cells and at 24 h DNA ladders emerged. However, none of the above results was found in human cortex neurons, but when exposed to 2 micromol/L As2O3, the activation of PKC and DNA ladders did emerge in neurons., Conclusions: The phosphorylation and dephosphorylation of PTK and PTP participated in nonspecific apoptosis signal transduction pathway related to As2O3, and accompanied with PKC activation. The [Ca(2+)]i elevation was closely related to increased PKC activation. There existed difference in dose tolerances to As2O3 between NB4 cell and cortex neurons.

Objective: To investigate the changes of apoptosis and the activity of caspases 3 and 9 in bone marrow hematopoietic progenitor cells in myelodysplastic syndromes (MDS)., Methods: Bone marrow hematopoietic progenitor cells (including both CD(34)(+) and CD(34)(-) cells) were collected by negative selection in 34 patients with MDS. Apoptosis was measured with Annexin V assay and activities of caspases 3 and 9 by spectrophotometer., Results: 1. Apoptosis was significantly increased in MDS-RA (39.5%, P < 0.01) and MDS-RAEB (31.0%, P < 0.05), but was not different statistically in MDS-RAEBt/AML (18.8%) compared with that of control. 2. Activities of caspases 3 and 9 increased 45 and 20 fold in MDS-RA, increased 14 and 2 fold in MDS-RAEB, respectively and was not increased in MDS-RAEBt/AML compared with that of control. 3. Apoptosis and activities of caspases 3 and 9 reduced in 3 cases of MDS-RAEB group who progressed into AML., Conclusion: Increased activities of caspases 3 and 9 may be one of causes of excessive apoptosis in MDS. With progress to AML, activities of caspases 3 and 9 and apoptosis reduced. Reduced activity of caspase 9 may result in apoptosis "escape" and progression into AML.

Objective: To study the effect of endogenous TGF-beta(1) and TNF-alpha on As(2)O(3) inducing apoptosis of HL-60 cells., Methods: The expressions of endogenous TGF-beta(1) and TNF-alpha in apoptotic HL-60 cells induced by As(2)O(3) were assayed by RT-PCR, quantitative RT-PCR, ELISA, DNA fragmentation and TUNEL. The effect of TGF-beta(1) and TNF-alpha antisense phosphorothioate oligodeoxynucleotides (PSODNs) on As(2)O(3) inducing apoptotic HL-60 cells was further studied., Results: (1) Expressions of endogenous TGF-beta(1) and TNF-alpha were significantly up-regulated in As(2)O(3) inducing apoptotic HL-60 cells (from 13,546 +/- 124 and 497,216 +/- 187 before treatment to 23,273 +/- 229 and 674,217 +/- 189 after treatment, respectively), accompanied with down-regulated bcl-2 mRNA expression (from 10,424 +/- 274 before treatment to 3,361 +/- 89 after treatment). (2) TGF-beta(1) and TNF-alpha antisense PSODNs could rescue As(2)O(3) induced apoptosis of HL-60 cells, with a restoration of bcl-2 gene expression., Conclusions: Endogenous TGF-beta(1) and TNF-alpha played an important role in As(2)O(3) inducing HL-60 cells apoptosis through down-regulation of bcl-2 expression.

Objective: To study the effects of arsenic trioxide (As(2)O(3)) on cell cycle and expression of cyclin dependent kinase inhibitors (CDKIs) in multiple myeloma (MM) cells, and explore its pharmacological mechanism., Methods: The DNA content of MM cells line HS-Sultan was analyzed by flow cytometry after exposure to As(2)O(3), the effects on expression of CDKI P15, P16 AND P21 were studied by reverse transcriptase PCR., Results: DNA flow cytometric analysis showed that As(2)O(3) induced most of HS-Sultan cells, arrest at G(0)/G(1) phase and a small fraction at G(2)/M phase and apoptosis occurred mainly in S phase. There was no expression of P15 and P16 mRNA in untreated HS-Sultan cells and 1.0 micromol/L As(2)O(3) could make them expressed after exposed 24 or 48 hours respectively. Expression of P12 mRNA was obviously elevated by As(2)O(3) comparing with that of control., Conclusion: One of the pharmacological mechanisms of As(2)O(3) is to activate the expression of CDKI P15, P16 and P21, and consequently affect cell proliferation cycle.

Objective: To investigate the potential effects of arsenic trioxide (As(2)O(3)) combined with 8-(4-chlorophenylthio) adenosine 3', 5'-cyclic monophosphate (8-CPT-cAMP) on the retinoic acid (RA)-resistant acute promyelocytic leukemia (APL) cells., Methods: The RA resistant APL cell lines NB4-R1 and NB4-R2 were used as in vitro models. The effect of As(2)O(3) and/or 8-CPT-cAMP was evaluated according to cellular morphology, cell surface antigen and nitroblue-tetrazolium (NBT) assay. Meanwhile, immunofluorescence analysis and Western blot assay were used to detect the degradation of PML-RAR alpha fusion protein and the change of several key cell cycle regulatory proteins in these cells before and after the treatment., Results: Low dose of As(2)O(3) (0.25 micromol/L) synergized with 8-CPT-cAMP (200 micromol/L) in inducing differentiation of NB4-R1 and NB4-R2 cells, while neither of these two drugs alone could induce differentiation of these cells. In addition, 8-CPT-cAMP was able to inhibit the cell growth by modulating the expression of some important cell cycle regulators and to facilitate the As(2)O(3)-mediated degradation of PML-RAR alpha fusion protein., Conclusions: As(2)O(3) combined with 8-CPT-cAMP could induce differentiation of RA-resistant APL cells.

Objective: To investigate the effects of arsenic trioxide (As(2)O(3)) on the apoptosis and P-glyco-protein (P-gp) expression of multidrug-resistant human leukemia K562/ADM cells, and the combined effects of As(2)O(3) with conventional chemotherapeutic agents., Methods: Multidrug-resistant human leukemia cell line K562/ADM that overexpresses mdr-1 gene was used as the target cells. The cell proliferating activity was assessed with a MTT assay. Cell morphology was examined by light microscopy, confocal microscopy and electron-microscopy. P-gp expression, cell-cycle status were determined by flow cytometry., Results: K562/ADM cells were highly resistant to adriamycin, and cross-resistant to daunorubicin and etoposide. As(2)O(3) at concentrations of 0.5 to 20 micromol/L inhibited the proliferation of K562/ADM cells, and K562/ADM cells were more sensitive to As(2)O(3) than their parent K562 cells did. As(2)O(3) induced marked apoptosis of K562/ADM cells showed by typical apoptotic morphological changes and the appearance of high sub-G(1) cell population. As(2)O(3) significantly inhibited the P-gp expression in K562/ADM cells, and exerted a synergistic effect on the enhancement of the cell sensitivity to adriamycin, daunorubicin and etoposide., Conclusion: As(2)O(3) induces growth-inhibition and apoptosis of multidrug-resistant K562/ADM cells, and augments synergistically the sensitivity of the cells to conventional chemotherapeutic agents via down-regulation of P-gp expression.

Objective: To investigate the mechanisms of arsenic trioxide (As(2)O(3)) induced demethylation., Method: Methylation of p15INK4B gene in MUTZ-1 cell was detected by PCR using a methylation specific primer (MSP), the expression of P15, DNA methyltransferase (DNMT) 1, DNMT3A and DNMT3B gene by RT-PCR, the As(2)O(3) induced growth inhibition of MUTZ-1 cell by MTT method., Results: P15 gene failed to express in MUTZ-1 cells after methylation. The expression was recovered after the cells exposed to As(2)O(3). As(2)O(3) could significantly down-regulate DNMT3A and DNMT3B but not DNMT1 gene on mRNA level in a dose dependent manner., Conclusion: As(2)O(3) could activate the expression of p15 gene by demethylation or/and by inhibiting DNMT3A and DNMT3B gene.

Objective: To investigate the effects of mitochondrial membrane permeability transition pore (MPT)-opened agent diamide and MPT-closed agent cyclosporin A on arsenic trioxide (As(2)O(3))-induced apoptosis in acute promyelocytic leukemia (APL) cell line NB4., Methods: NB4 cells were treated with As(2)O(3) alone or in combination with diamide or cyclosporin A in different concentrations. Cell apoptosis was assessed by the morphological observation, Annexin-V assay, distribution of cellular DNA contents and genomic DNA electrophoresis. The mitochondrial transmembrane potentials (DeltaPsim) were detected by flow cytometry according to the intensity of rhodamine 123 uptake in cells., Results: Both diamide and cyclosporin A significantly enhanced As(2)O(3)-induced apoptosis in NB4 cells. The DeltaPsim collapse induced by As(2)O(3) was also enforced by combined treatment with diamide or cyclospo-rin A. 1 micromol/L As(2)O(3) alone treatment for 72 hours led to DeltaPsim disruption in 27.9% of cells, while combined treatment of As(2)O(3) and diamide or cyclosporin A increased DeltaPsim disruption cells to 59.7% and 42.2%, respectively., Conclusions: As(2)O(3)-induced DeltaPsim disruption possibly involves with thiol oxidation or crosslink of important components especially ANT-related molecules.

Objective: To investigate whether ascorbic acid could enhance the efficacy of arsenic trioxide (As(2)O(3)) combined with 2, 3-dimethoxy-1, 4-naphthoquinone (DMNQ) in inducing the apoptosis of leukemia cell line U937 and its possible mechanism., Methods: Flow cytometry and electron microscopy were applied to detect apoptosis of U937 cells after treatment with various combinations of As(2)O(3), DMNQ and ascorbic acid for 24 hours., Results: As(2)O(3) and DMNQ induced-apoptosis of U937 cells was enhanced (35.24%-->61.20%) upon cotreatment with ascorbic acid. Catalase could reverse this effect of DMNQ. Ascorbic acid had no effect on DMNQ-induced apoptosis of U937 cells., Conclusion: Ascorbic acid enhanced the apoptosis of U937 cells via reactive oxygen species-dependent pathway in the presence of As(2)O(3).

Objective: To explore the correlation between arsenic trioxide and gene methylation in an acute lymphoblastic cell line., Methods: Methylation of p15 gene in Molt4 cell line was detected by polymerase chain reaction (PCR) using methylation specific primer (MSP) and the expression of this gene after arsenic trioxide treatment was detected by reverse transcriptase PCR (RT-PCR). The cell cycle and cell growth curve were also observed by flow cytometry., Results: p15 gene failed to express in molt4 after methylation. The expression was recovered, cell growth was inhibited, and G(1) cell cycle arrest was observed, when the cells exposed to arsenic., Conclusion: Arsenic trioxide could activate the expression of p15 gene and reverse cell cycle negative regulation.

Objective: To investigate the regulation of telomerase activity in HL-60 and NB4 cells exposed to arsenic trioxide (As(2)O(3))., Methods: Cell morphology, intracellular DNA distribution, bcl-2 expression and telomerase activity were evaluated in HL-60 and NB4 cells exposed to As(2)O(3) or ATRA., Results: The differentiation induction of HL-60 and NB4 cells by low concentration of As(2)O(3) was weaker than that by ATRA, but downregulation effect of As(2)O(3) on telomerase activity was more strong and quick. Higher concentration of As(2)O(3) induced apoptosis in HL-60 or NB4 cells accompanied by more rapid down regulation of telomerase activity and bcl-2 expression. Neither As(2)O(3) nor ATRA showed direct inhibition effect on telomerase activity., Conclusion: The downregulation of telomerase activity by low concentration of As(2)O(3) in HL-60 and NB4 cells is the result of overlap of differentiation and apoptosis. There are similar mechanisms in the regulation of telomerase activity and apoptosis in different leukemia cells. Bcl-2 may play an important role in these mechanisms.

Objective: To investigate molecular mechanism of tissue factor (TF) expression on acute promyelocytic leukemia cell line NB4 cells down-regulated by all-trans retinoic acid (ATRA) and arsenic trioxide (As(2)O(3))., Methods: Cyclohexamide (CHX) inhibition test for de novo protein synthesis and actinomycin D (Act D) inhibition test for RNA synthesis were used to check the effect of ATRA on the TF expression. TF antigen of U937 cells transfected with pMSCV-PML-RARalpha treated with or without ATRA and As(2)O(3) was detected., Results: CHX treatment completely suppressed the down-regulation effect of ATRA on the TF mRNA expression, Act D inhibition test showed that half-life of TF mRNA in treated NB4 cells was shortened to about 30 min from that of around 60 min in untreated NB4 cells. The TF antigen contents in U937 cells transfected with pMSCV-PML-RARalpha were significantly higher than that in transfected U937 cells with retrovirus vector. Both ATRA and As(2)O(3) could down-regulate the TF antigen level in U937 cells transfected with or without PML-RARalpha., Conclusion: The modulation of the TF mRNA expression in NB4 cells by ATRA might be indirect. TF mRNA destabilization was involved in the TF regulation process mediated by ATRA. Elevated TF antigen level in U937 cells transfected with pMSCV-PML-RARalpha may be related to the fusion protein PML-RARalpha. The down-regulation effect of ATRA and As(2)O(3) on the TF expression of U937 cells might not involve the fusion protein.

Objective: To explore the mechanisms of As2O3 inducing apoptosis and growth inhibition in K562 cells and provide theoretical basis for clinical application., Methods: The effects of As2O3 on BCR/ABL protein tyrosine phosphorylation(PTP) and its signal transduction as well as the expression of apoptosis-related genes were studied by means of immunoprecipitation, Western blot, biochemical method and immunofluorescence., Results: Tyrosine phosphorylation of several cellular proteins especially BCR/ABL protein was decreased by 1 mumol/L As2O3, but not by 0.1 mumol/L As2O3. As2O3 had no effect on PTP activity, downregulated the expression of JAK2 protein, but did not affect the expressions of STAT1 and STAT2 proteins and the STAT1 protein tyrosine phosphorylation. As2O3 had no effect on the expression of the apoptosis-related genes like Bcl-2, Bcl-xL/S, Bax, ICH-1L, p53, PARP, either, but downregulated PML protein expression in K562 cells., Conclusion: As2O3 might induce K562 cell apoptosis and inhibit its growth by reducing tyrosine phosphorylation of cellular proteins especially BCR/ABL protein and/or by downregulating JAK2 protein expression to interfere with the BCR/ABL protein signal transduction.

Objective: To investigate the effects of all-trans retinoic acid(ATRA), arsenic trioxide(As2O3) and daunorubicin(DNR) on tissue factor(TF) expression in acute promyelocytic leukemia (APL) cell line NB4 cells., Methods: Procoagulant activity(PCA) of NB4 cells treated with 1 mumol/L ATRA, 1 mumol/L As2O3 or 0.2 microgram/ml DNR was detected using one-stage clotting assay, TF antigen by ELISA, and TF mRNA by RT-PCR., Results: Both ATRA and As2O3 could down-regulate the TF antigen, its mRNA transcription and membrane PCA of NB4 cells with a time-dependent manner, while DNR was shown to increase these parameters. Moreover, by dideoxy sequencing of DNA fragment derived from PCR, it was found that there was a exon 5 deletion transcript of TF in APL cells. Its biological significance remained unknown., Conclusion: TF expression and PCA of APL cells may be down-regulated by ATRA and As2O3, therefore, As2O3 might also improve DIC-related hemorrhage of APL while inducing APL cells to apoptosis. The distinct regulation of TF and PCA on APL cells by As2O3 and DNR may at least partially contribute to their effects on APL coagulopathy through the influence on coagulant factors activation.

Objective: To explore the relationship among intercellular -SH, caspase, retinoic acid (RA) and arsenic trioxide(As2O3)-induced apoptosis., Methods: The in vitro effect of different thiols compounds, RA and caspase inhibitors on As2O3-induced apoptosis in NB4 and HL-60 cells was studied., Results: 1. NAC completely blocked, BSO potentiated while MTG, BAL had no effect on As2O3-induced apoptosis. 2. Z-VAD.fmk blocked while Y-VAD.fmk had no effect on As2O3-induced apoptosis. 3. RA and As2O3 showed synergism in HL-60 cells, while showed antagonism in NB4 cell., Conclusions: 1. As2O3 binds with intracellular -SH, changes signal transduction, selectively activates caspase and causes apoptosis. 2. The regulating effect of RA on As2O3-induced apoptosis depends on cell types.

Objective: To study the possible mechanism of red orpiment, which is main component of composite indigo naturalis tablets, in the treatment of acute promyelocytic leukemia(APL)., Methods: The effect of red orpiment on induction of APL cell line NB4 and HL-60 apoptosis were studied by cell morphology, DNA gel electrophoresis and flow cytometry assay., Results: Red orpiment induced NB4 and HL-60 cell apoptosis. When treated with different concentration of red orpiment(25-200 micrograms/ml) for 16 hours, both NB4 and HL-60 cells showed typical apoptosis features. If decreased the concentration of red orpiment to 12.5 micrograms/ml, the NB4 cell still showed apoptosis features while the HL-60 cell did not when cultured for 72 hours. Arsenic disulfide(As2S2) had the same effect as red orpiment did under the same experiment condition., Conclusion: It is the main component, As2S2 of the red orpiment that can induces NB4 and HL-60 cell apoptosis. and the red orpiment is responsible for the high CR rate of APL induced by the composite indigo naturalis tablets.

Objective: To study the possible mechanisms of arsenic trioxide (As2O3) in the treatment of acute promyelocytic leukemia (APL)., Methods: Retinoic acid resistant APL cell line MR-2 was used as in vitro model. The effect of As2O3 on MR-2 cell line was observed by cell viability, cell growth, cell morphology, flow cytometry assay, NBT reduction test and immunofluorescence analysis., Results: 1.0 mumol/L of As2O3 could induce apoptosis of MR-2 cells and it correlated with the degradation of PML-RAR alpha fusion protein., Conclusions: The therapeutic effect of As2O3 for APL possibly differs from that of ATRA, however, PML-RAR alpha fusion protein may be the target of both the therapy.

Objective: To explore the mechanism of arsenic trioxide (As2O3) induced apoptosis in K562 cell line., Methods: Immunoprecipitation was used to obtain BCR/ABL and ABL proteins. The activities of PTK and tyrosine phosphorylation were measured by biochemical method and Western blot, respectively., Results: As2O3 reduced the PTK activities of cytosol and membrane proteins and BCR/ABL and ABL proteins. The tyrosine phosphorylation of 180,000 and 125,000 proteins declined., Conclusion: As2O3 may interfere the signal transduction of BCR/ABL protein by reducing its PTK activity and induce K562 cell apoptosis.

Objective: To illustrate mechanisms of arsenic trioxide(As2O3) in the treatment of acute promyelocytic leukemia (APL)., Methods: Cell-DNA content distribution, CD11b and CD33 antigens and nitroblue tetrazolium (NBT) reduction were evaluated in fresh APL cells from six APL patients treated in vitro with As2O3., Results: As2O3 had double effects on the cells inducing apoptosis and inducing partial differentiation at higher and at lower drug concentrations, respectively. As2O3 (0.1 approximately 2.0 micromol/L) could rapidly modulate and degrade APL-specific marker molecule PML-RARalpha protein, which could play an important role in the effects of As2O3 on APL cells., Conclusion: As2O3 had double effects (induction of apoptosis and partial differentiation) on APL cells through the modulation and degradation of PML-RARalpha proteins.

Objective: To illustrate the possible cellular and molecular mechanisms of arsenic trioxide (As2O3) in the treatment of acute promyelocytic leukemia (APL)., Methods: APL cell line NB4 was used for in vitro studies. The effect of As2O3 on APL was studied by using flow cytometry, DNA electrophoresis, Narthern blotting and Western blotting., Results: As2O3 induced NB4 cell apoptosis, while not inhibiting the growth and survival of two other leukemic cell lines (HL-60 and U937). Furthermore, As2O3 effectively down-regulated the expression of bcl-2 gene without changing the mRNA levels of other apoptosis-associated genes (including p53, c-myc, bax and bcl-XL)., Conclusion: These might be one of the molecular mechanisms of As2O3 induced NB4 cell apoptosis.

Objective: In order to illustrate the possible roles of PML-RARalpha protein in arsenic trioxide (AsO3)-induced NB4 cell apoptosis., Methods: Effects of As2O3 on the subcellular localization of PML-RARalpha in NB4 cells were studied., Results: (1) Anti-PML serum staining was reduced and PML granules emerged in the perinuclear cytoplasm in a diffuse pattern in HL-60 cells under As2O3 treatment; (2) abnormal PML/PML-RARalpha granules were decreased; (3) NB4 cells accumulated anti-PML serum staining granules in the cytoplasms were increased and similar accumulation also found in apoptotic cells; and (4) pretreatment with all-trans retinoic acid (ATRA) for 24 or 48 hours did not alter the As2O3 effects., Conclusion: As2O3-induced apoptosis was independent of the retinoic acid signal pathway, and it might be regulated by PML/PML-RARalpha and/or other related genes.