OBJECTIVETo study the expression of annexin II (AnnII) and the fibrinolytic activity in NB4 cells and their alterations in the presence of arsenic trioxide (ATO) and daunorubicin (DNR).

METHODSLeukemia cell line NB4 was treated with ATO or DNR for 24 ∼ 72 h. Cell surface expression of AnnII and its mRNA were analysed by flow cytometry and real time PCR, respectively, the fibrinolytic activity by chromogenic assay.

RESULTSCompared with other acute leukemia cell lines, the expression of AnnII on untreated NB4 cells was relatively higher. The AnnII positive cell rates on NB4, HL-60, K562, and A3 cells were (94.5 ± 1.6)%, (40.1 ± 2.1)%, (36.3 ± 1.5)% and (11.8 ± 2.5)%, respectively. The fibrinolytic activity of NB4 cells was the greatest with a A value of 0.68 ± 0.02. The fibrinolytic activity of NB4 cells was obviously decreased by ATO, DNR or monoclonal antibody against AnnII, being decreased by 60.4%, 35.8% and 26.0% of the pretreatment level, respectively. The expressions of AnnII and its mRNA in NB4 cells were decreased dramatically after ATO and DNR treated for 48 h. Annexin II positive cells rate were (55.46 ± 4.72)% and (27.00 ± 6.18)%, respectively.

CONCLUSIONNB4 cells have strong ability to enhance the catalytic efficiency of the t-PA-dependent plasminogen activation and AnnII on the cell membrane contributes to this activity. Its high fibrinolytic activity can be corrected by ATO and DNR through down-regulating AnnII.

Annexin A2 ; Apoptosis ; Daunorubicin ; HL-60 Cells ; Humans ; Leukemia ; metabolism

To observe the expression of cyclin D1, hTERT, and telomerase activity in MNC, HL-60, HL-60A and to explore their effects on leukemogenesis and drug-resistance, normal human peripheral blood mononuclear cells, HL-60 cells sensitive to adriamycin and HL-60A cells resistant to adriamycin were investigated. The cell cycle was analyzed by flow cytometry, and the apoptosis was analyzed by Annexin V-FITC(+) PI staining. Expressions of cyclin D1 and hTERT were determined by real-time PCR and Western blot. Telomerase activity was detected by TRAP-ELISA. The results indicated that the percentage of MNC, HL-60 and HL-60A in S phase was (10.21 + 2.11)%, (44.93 + 3.00)%, and (51.38 + 1.10)% respectively; the percentage of apoptosis cells was (16.14 + 2.13)%, (7.53 + 0.92)%, (4.15 + 0.96)% respectively; the expression of mRNA and protein for cyclin D1 and hTERT increased; the telomerase activities of HL-60 and HL-60A were higher (p = 0.000), whereas the difference between HL-60 and HL-60A was no statistically significant (p = 0.232); positive correlation between cyclin D1, hTERT and telomerase activity had been found (p < 0.01). It is concluded that the cells of S phase increased while the apoptotic cells decreased in HL-60 and HL-60A, especially in HL-60A, which may be due to the up-regulation of cyclin D1, hTERT and telomerase activity.
Cell Cycle ; Cyclin D1 ; metabolism ; HL-60 Cells ; Humans ; Leukemia ; metabolism ; Telomerase ; metabolism

The aim of this study was to investigate the expression of histone demethylase lysine specific demethylase1 (LSD1) in patients with acute leukemia (AL) and its clinical significance. LSD1 protein expression level was detected by semi-quantitative Western blot in HL-60 and SHI-1 leukemia cell line, in bone marrow mononuclear cells of acute AL patients with different condition [new diagnosis, complete remission (CR) and relapse] and in patients with non malignant hematopathy (control). Clinical data of AL patient followed up was collected. The relationship of LSD1 expression level with clinical prognosis was analyzed. The results showed that in HL-60 and SHI-1 leukemia cell line, LSD1 expression was strong positive, relative amount (LSD1/β-actin gray level rate) was 4.647 ± 3.840 and 1.628 ± 0.185 (n = 4) respectively. In 72 AL patients, LSD1 expression levels were quite different. LSD1 positive rate was 56.9% (41/72), average relative amount was 1.053 ± 1.976. In 17 controls, LSD1 positive rate was 0%, relative amount was 0.004 ± 0.012. The LSD1 positive rate in newly diagnosed AML or ALL group (90.4%, 77.8%) and refractory/relapse AML or ALL group (100%, 100%) was higher than that in AML or ALL CR group (4.7%, 0%) (p = 0.000), relative amount of LSD1 showed no statistically difference between newly diagnosed AML and ALL groups (1.177 ± 1.646, 1.275 ± 1.845) or refractory/relapse group (2.050 ± 2.470, 4.107 ± 3.676) and CR group (0.029 ± 0.033, 0.019 ± 0.024) (p > 0.05). In all AL patients, LSD1 positive rate in newly diagnosed (84.6%) and refractory/relapse groups (100%) was higher than that in CR group (3.8%). LSD1 relative amount in newly diagnosed group (1.274 ± 1.760), refractory/relapse group (3.359 ± 3.319) and CR group (0.027 ± 0.031) was higher than that in control group (p < 0.01), and in refractory/relapse group was higher than that in newly diagnosed group and CR group (p < 0.01), in newly diagnosed group was higher than that in CR group (p < 0.01). It is concluded that overexpression of LSD1 is correlated with refractory or relapse in AL. LSD1 expression level can reflect disease status of AL patients and may be a predictive biomarker for unfavourable prognosis of AL.
HL-60 Cells ; Histone Demethylases ; metabolism ; Humans ; Leukemia ; metabolism ; Leukemia, Myeloid, Acute ; metabolism ; Recurrence

The nature of the endonucleases responsible for DNA fragmentation in apoptosis has not yet been clearly defined. The intracellular acidity has been known to greatly affect apoptosis probably by affecting the activity of the endonucleases. In this study, the implication of pH in the apoptosis was investigated through the use of human HL-60 leukemia cells. The cells were incubated in media with different pH ranging from 3.5 to 7.5 for 4 hrs and the mode of cell death was investigated. The trypan blue exclusion assay showed that close to 25% and 90% of the cells were dead when incubated in pH 6.4 and pH 5.0 media, respectively. The agarose gel electrophoresis of DNA demonstrated that significant DNA fragmentation occurred in the HL-60 cells incubated in the pH 6.2-6.4 media for 4 hr indicating cell death by apoptosis. The electron microscopy study also demonstrated that many of the cells incubated in the pH 6.4 medium were in the process of apoptosis while the cells maintained in the pH 5.0 medium were dying by necrosis. The intracellular pH (pHi) of HL-60 cells was 6.6-6.9 when the extracellular pH (pHe) was 6.2-6.4. These results demonstrated that DNase I which has a maximal endonuclease activity near pH 7.0 may be responsible for the apoptosis accompanied by DNA fragmentation in HL-60 cells in the pH 6.4 medium. This observation is at variance with the previous reports that DNase II mediate the DNA fragmentation in apoptosis. The cell death at extremely low pH (pH 5.0) appeared to be due mainly to necrosis.
*Apoptosis ; DNA Damage ; HL-60 Cells/metabolism/*pathology ; Human ; Hydrogen-Ion Concentration ; Support, Non-U.S. Gov't

CD40 Ligand ; pharmacology ; HL-60 Cells ; drug effects ; Humans ; fas Receptor ; metabolism

OBJECTIVETo investigate the inhibitory effects of CaMKIIN on acute myeloid leukemia cell line HL-60 to explore a novel therapeutic target of leukemia.

METHODSHuman CaMK II N gene expression vector pcDNA3.1/hCaMKIIN or empty vector pcDNA3.1/myc-His (-) B was transfected into HL-60 cells by Lipofectamine 2000. Human CaMK II N proteins of transfected cells were detected by Western blot. Cell proliferation affected by human CaMKIIN was determined by MTT. Colony-forming assay was performed by soft agar growth system. The cells transfected with CaMKIIN were stained with Hoechst 33342 to detect the apoptotic proportion under fluorescence microscopy. Cell cycle was analyzed by flow cytometry.

RESULTSHuman CaMKIIN was stably transfected into HL-60 cells, and overexpression of human CaMKIIN inhibited the proliferation of HL-60/CaMKIIN cells compared to HL-60/mock cells and HL-60 cells [(0.44 ± 0.03) vs (0.94 ± 0.05) vs (0.94 ± 0.04), P<0.01]. The colony formation of HL-60/CaMKIIN was also markedly smaller[(21.00 ± 3.05)/500] than that of mock-transfected [(111.00±4.58)/500]] and control cells [(119.00±6.09)/500] (P<0.01). After 72 hrs-culture, the apoptotic proportion in cells transfected with CaMK II N was obviously higher than of cells transfected with mock DNA or control [(22.49 ± 2.15)% vs (7.17 ± 0.72)% vs (6.40 ± 0.55)%, P<0.01]. Up to (82.97 ± 2.90)% human CaMKIIN/HL-60 cells were arrested at G0/G1 phase, which was more than mock-transfected [(40.53 ± 2.38)%] and control cells [(41.63 ± 2.27)%] (P<0.05). Human CaMKIIN could down-regulate expression of Bcl-2 in transfected cells.

CONCLUSIONCaMK IIN up-regulation could inhibit proliferation and induce apoptosis of human acute myeloid leukemia cell HL-60.

Apoptosis ; Cell Proliferation ; Genetic Vectors ; HL-60 Cells ; Humans ; Proteins ; genetics ; metabolism ; Transfection ; Up-Regulation

OBJECTIVE: To investigate the effect of targeting the silent information regulator 2 hemolog 2 (SIRT2) expression on the apoptosis of drug-resistant AML cell line HL-60/A and its mechanism. METHODS: The expression of SIRT2 and antophagy-related protein LCT, P62 in HL-60/A and HL-60 was detected by Western blot, the effect of cytorabine on the apoptosis of HL-60/A cells was detected by using Annexin V/PI double staining after targeting inhibition of SIRT2 expression resulting from transfecting HL-60/A cells with SiRNA. The Western blot and transmission electray microscopy were used to detect the cell autophagy. To further clarify the role of autophragy in the regulatory effect of SIRT2 on the drug-resistance of HL-60/A cells, the autophagy-specific agonist, repamycin, was added into the cell culture medium after SIRT2-siRNA transfection. Then, the autophagy and apoptosis of HL-60/A were detected, respectively. RESULTS: The SIRT2 protein expression obviously increased in HL-60/A cells than that in HL-60 cells. Moreover, the expression rate of LC3II/I was higher, but P62 expression was lower in HL-60/A cells. After siRNA successfully transfecting into HL-60/A cells, quantitative PCR and Western blot should that the expression of SIRT2 significantly decreased. Meawhile, Western blot showed that the expression of LC3 II/I decreased, but P62 increased. Meanwhile, By TEM found that the number of autophagosome also decreased, suggesting the autophagy was inhibited after down-regulation of SIRT2. In addition, the drug senstivity of HL-60/A cells to cytarabine in siRNA-transfection group increased, and the apoptotic rate detected by Annexin V/PI double staining significantly increased. However, after co-culture with rapamycin, the suppressed autophagy in siRNA-trasfect HL-60/A cells was activated, leading to the reappearance of drug resistance of cells to cytarabine, and more significantly decrease of apoptotic rate. CONCLUSION The high expression of SIRT2 in HL-60/A cells activates the protective autophagy mechanism, which closely related with drug resistance.
Apoptosis ; Autophagy ; Drug Resistance, Neoplasm ; HL-60 Cells ; Humans ; Sirtuin 2 ; metabolism

The high expression of tissue factor (TF) is related to the coagulation disorder in acute leukemia. TF in blood circulation is mainly expressed in cells, microparticles (MP) and alternatively spliced human tissue factor (asHTF). To elucidate the role of TF in the coagulation disorder of acute myeloid leukemia (AML), RT-PCR was performed on 6 common AML cell lines NB4, HL-60, Kasumi-1, U937, K562 and THP-1. The results showed that only NB4 and U937 cells expressed baseline full-length TF and asHTF which were proved by sequencing. The flow cytometric detection, TF activity and TF antigen tests in NB4 and U937 cells revealed that the asHTF was expressed in trace amount and almost had no activity, while the TF antigen and activity in microparticles were significantly higher than that in asHTF. It is concluded that asHTF may play an unimportant role in the coagulation disorder of AML. Microparticle associated tissue factor (MP-TF) is the predominant source of TF activity released from AML cells.
Alternative Splicing ; HL-60 Cells ; Humans ; Leukemia, Promyelocytic, Acute ; genetics ; metabolism ; Thromboplastin ; genetics ; metabolism ; Tumor Cells, Cultured ; U937 Cells

The objective of this study was to explore the effect of astragalus polysaccharide (APS) on sensitivity of leukemic cell line HL-60 to NK cell cytotoxicity and its mechanism. The cytotoxicities of NK cells against HL-60 cells were analyzed by LDH releasing assay at different effect-to-target cell ratios (E:T) before and after treated with APS. The gene expression of MHC class I chain-related (MICA) in HL-60 cells before and after APS treatment was assayed with RT-PCR. Protein expression of MICA in HL-60 cells was assayed by flow cytometry before and after treated by APS. The results showed that after treated with APS 15 mg/ml for 48 h, the cytotoxicities of NK cells against HL-60 cells enhanced at different effect-to-target (P < 0.05), and the gene and protein expressions in MICA of HL-60 cells were up-regulated (P < 0.05). It is concluded that the APS can obviously up-regulate the expression of MICA in HL-60 cells, thus enhance sensitivity of HL-60 cells to cytotoxicity of NK cells.
Astragalus Plant ; Cytotoxicity, Immunologic ; drug effects ; HL-60 Cells ; Histocompatibility Antigens Class I ; metabolism ; Humans ; Killer Cells, Natural ; Polysaccharides ; pharmacology

This study was purposed to investigate the impact of human umbilical cord-derived mesenchymal stem cells (hUC-MSC) on the sensitivity of HL-60 cells to therapeutic drugs so as to provide more information for exploring the regulatory effect of hUC-MSC on leukemia cells. Transwell and direct co-culture systems of HL-60 and hUC-MSC were established. The apoptosis and cell cycle of HL-60 cells were detected by flow cytometry. RT-PCR and Western blot were used to detect the mRNA and protein levels of Caspase 3, respectively. The results showed that the apoptosis of HL-60 induced by cytarabine (Ara-C) decreased significantly after direct co-cultured with hUC-MSC cycle mRNA (P < 0.05). The similar phenomenon was observed in transwell co-culture system. Cell cycle of HL-60 cells were arrested at G0/G1 phase and did not enter into S phase (P < 0.05) and the expression of Caspase-3 mRNA and protein in HL-60 cells were reduced (P < 0.05). It is concluded that hUC-MSC protected HL-60 from Arc-C induced apoptosis through regulating the cell cycle and down-regulating expression of Caspase 3 in HL-60 cells. In addition, this effect is caused by the soluble factors from hUC-MSC.
Apoptosis ; Caspase 3 ; metabolism ; Coculture Techniques ; Cytarabine ; pharmacology ; HL-60 Cells ; Humans ; Mesenchymal Stromal Cells ; cytology ; Umbilical Cord ; cytology