甘草查尔酮A对HL-60细胞恶性生物学行为的抑制作用及其机制

目的 探究甘草查尔酮A(LA)对急性髓系白血病(AML)细胞HL-60的作用及其机制。方法 将人AML细胞系HL-60细胞分为对照组、LA组(30μmol/L)、IL-6组(100 ng/mL,JAK2/STAT3信号通路激活剂)和LA+IL-6组。培养48 h后,采用MTT法和克隆形成实验检测HL-60细胞增殖活性;采用流式细胞术检测HL-60细胞周期分布和细胞凋亡;采用Transwell实验检测HL-60细胞侵袭和迁移;采用Western blot检测p21、p27、cyclin E2、CDK2、Bcl-2、Bax、cleaved-Caspase-3、p-JAK2,JAK2,p-STAT3和STAT3蛋白表达水平。结果 与对照组比较,LA组细胞活力、克隆形成数、侵袭和迁移细胞数均降低(P<0.05),Bcl-2、cyclin E2和CDK2蛋白表达量均降低(P<0.05),JAK2和STAT3蛋白的磷酸化水平均降低(P<0.05);G0/G1期细胞比例和细胞凋亡率均升高(P<0.05),p21、p27、Bax和cleaved Caspase-3蛋白表达量均升高(P<0.05)。与对照组比较,IL-6组细胞活力、克隆形成数、侵袭和迁移细胞数均升高(P<0.05),Bcl-2、cyclin E2和CDK2蛋白表达量均升高(P<0.05),JAK2和STAT3蛋白的磷酸化水平均升高(P<0.05),G0/G1期细胞比例和细胞凋亡率均降低(P<0.05),p21、p27、Bax和cleaved Caspase-3蛋白表达量均降低(P<0.05)。与IL-6组比较,LA+IL-6组细胞活力、克隆形成数、侵袭和迁移细胞数均降低(P<0.05),Bcl-2、cyclin E2和CDK2蛋白表达量均降低(P<0.05),JAK2和STAT3蛋白的磷酸化水平均降低(P<0.05),G0/G1期细胞比例和细胞凋亡率均升高(P<0.05),p21、p27、Bax和cleaved-Caspase-3蛋白表达量均升高(P<0.05)。LA+IL-6组和LA组间上述指标差异没有统计学意义。结论 甘草查尔酮A可抑制AML细胞系HL-60细胞增殖、侵袭和迁移,诱导细胞凋亡并将细胞阻滞在G0/G1期,其作用机制可能与抑制JAK2/STAT3信号通路激活有关。

蟾毒它灵诱导急性早幼粒细胞白血病HL⁃60细胞铁死亡的机制研究

目的探究蟾毒它灵(Bufotalin)对急性早幼粒细胞白血病(acute promyelocytic leukemia,APL)细胞HL‐60铁死亡的作用及机制。方法用不同浓度(0.1、0.5、1.0、2.0、4.0μg·mL^(-1))蟾毒它灵分别作用于APL细胞HL‐60,使用光学显微镜观察细胞的形态学变化;采用CCK‐8法检测细胞的存活率情况;采用Western blot法检测细胞中铁死亡相关蛋白CD71、xCT、FTH1、GPX4的表达水平;采用谷胱甘肽(GSH/GSSG)检测试剂盒检测细胞内GSH和GSSG的含量变化;采用脂质氧化(MDA)检测试剂盒测定细胞内MDA的含量变化。将0.5μg·mL^(-1)蟾毒它灵、0.1μmol·L^(-1)Fer‐1和0.5μg·mL^(-1)蟾毒它灵+0.1μmol·L^(-1)Fer‐1分别作用于HL‐60细胞,使用光学显微镜观察细胞形态学变化,并用Western blot法检测铁死亡相关蛋白的表达水平。结果不同浓度蟾毒它灵处理HL‐60细胞后,细胞形态呈现出哑铃型、梭形等不规则形状,细胞的存活率降低,且呈时间‐剂量依赖关系。与对照组相比,蟾毒它灵可降低铁死亡相关蛋白GPX4、xCT、FTH1的表达水平和总谷胱甘肽的含量(均P<0.01),升高CD71蛋白的表达水平和MDA含量(均P<0.05)。蟾毒它灵与铁死亡抑制剂Fer‐1联合处理HL‐60细胞后,与对照组比较,HL‐60细胞的生长数量和形态学无明显变化,CD71、xCT、FTH1、GPX4蛋白表达水平的差异也无统计学意义(均P>0.05)。结论蟾毒它灵可抑制APL细胞HL‐60的增殖并诱导铁死亡,其可能通过GPX4介导的抗氧化途径和铁代谢途径实现。

miR-186对HL-60细胞增殖、迁移的调控及机制研究

目的 探讨过表达微小RNA-186(miR-186)对人原髓细胞白血病HL-60细胞上皮间质转化(EMT)、增殖、迁移及磷脂酰肌醇3-激酶(PI3K)/丝苏氨酸蛋白激酶(AKT)信号通路的调控作用。方法 选取体外培养HL-60细胞,按照不同的转染方式分为对照组、mimic NC组、miR-186组、miR-186+抑制剂组、miR-186+激活剂组。采用实时荧光定量聚合酶链反应、5-乙炔基-2′脱氧尿嘧啶核苷(EdU)、Transwell小室法及蛋白免疫印迹法检测miR-186相对表达水平、增殖率、迁移率、EMT相关因子及其信使RNA(mRNA)相对表达水平并进行比较、分析。结果 与mimic NC组相比,miR-186组HL-60细胞miR-186相对表达水平、E-钙黏蛋白(E-cadherin)及其mRNA表达水平升高,差异均有统计学意义(P<0.05),而增殖率、迁移率、磷酸化(p)-PI3K、p-AKT、N-钙黏蛋白(N-cadherin)、波形蛋白(Vimentin)、纤维粘连蛋白(FN)及其mRNA表达水平降低,差异均有统计学意义(P<0.05)。与miR-186组相比,miR-186+抑制剂组HL-60细胞E-cadherin及其mRNA表达水平升高,差异均有统计学意义(P<0.05),而增殖率、迁移率、p-PI3K、p-AKT、N-cadherin、Vimentin、FN及其mRNA表达水平降低,差异均有统计学意义(P<0.05);与miR-186组相比,miR-186+激活剂组HL-60细胞E-cadherin及其mRNA表达水平下降,差异均有统计学意义(P<0.05),而增殖率、迁移率、p-PI3K、p-AKT、N-cadherin、Vimentin、FN及其mRNA表达水平升高,差异均有统计学意义(P<0.05)。结论 过表达miR-186通过阻遏PI3K/AKT信号通路抑制HL-60细胞EMT,进而抑制HL-60细胞增殖和迁移。

枸杞多糖促进HL-60细胞的吞噬功能

目的探究枸杞多糖(lycium barbarum polysaccharide,LBP)对人中性粒细胞株HL-60细胞吞噬功能的影响及其相关机制。方法采用不同浓度(0,1,10,100,200,500μg/mL)LBP刺激HL-60细胞24 h后,通过CCK-8和流式细胞术检测HL-60细胞的存活率和吞噬功能变化情况,通过免疫印迹法(Western blot)检测HL-60细胞磷脂酰肌醇-3-激酶(PI3K)信号通路Akt磷酸化情况。阻断实验分为对照组、LBP组、LBP+PI3K抑制剂(Wortmannin)组。LBP组以200μg/mL LBP单独刺激HL-60细胞24 h;LBP+Wortmannin组先以1μmol/L Wortmannin预刺激HL-60细胞2 h,再加入200μg/mL LBP继续作用24 h后检测HL-60细胞吞噬功能情况。为了检测HL-60细胞表面受体的表达情况,实验分为对照组和LBP组(200μg/mL),采用流式细胞术检测CD36、CD204、CD209、胶原样结构巨噬细胞受体(macrophage receptor with collagenous structure,MARCO)和Dectin吞噬相关受体表达情况。结果不同剂量LBP处理后,HL-60细胞的存活率未发生明显变化(P>0.05);与0μg/mL LBP比较,1~200μg/mL LBP刺激HL-60细胞吞噬百分率明显增加(P<0.01);与对照组比较,200μg/mL LBP组磷酸化Akt表达增加(P<0.05)。PI3K阻断实验表明,与LBP组比较,LBP+Wortmannin组LBP促进HL-60吞噬E.coli的效应部分抑制(P<0.05)。与对照组比较,LBP组HL-60细胞MARCO受体表达水平明显增加(P<0.05),而CD36、CD204、CD209和Dectin无明显变化(P>0.05)。结论LBP通过PI3K-Akt信号通路促进HL-60细胞吞噬E.coli,这种吞噬功能的提高可能与MARCO受体表达上调有关。

Apoptosis Induced by Bcl-2 Antisense Peptide Acid in HL60 Cells

Objective To study the differences and similarities of the antisense drugs with different structures on the biological functions of HL60 cells. Methods Cytotoxic effects were measured by cell viability assay. The expression levels of protein were assayed by immunofluorescence using fluoresce isothiocyanate label. The morphological changes in apoptotic cells were observed. Flow cytometric analysis of DNA fragmentation was also performed. Results Antisense peptide nucleic acid (PNA) targeting the coding region of the Bcl-2 mRNA could effectively inhibit the growth of HL60 cells, down-regulate the synthesis of Bcl-2 protein and induce apoptosis. After HL60 cells were treated with 10 μmol/L Bcl-2 antisense PNA or antisense oligonucleotide for 72 h respectively, apoptotic rates of HL60 cells were 17.80±1.53 and 13.17±1.12, respectively( P <0.05). Conclusion Antisense PNA targeting the coding region of Bcl-2 mRNA may have stronger antisense effects than the antisense oligonucleotides and could induce apoptosis of HL60 cells.

ARSENIC TRIOXIDE DOWNREGULATES TELOMERASE ACTIVITY IN HL-60 CELLS

Objective: To evaluate whether arsenic trioxide (AS2O3) could downregulate human telomerase reverse transcriptase (hTERT) gene expression and telomerase activity during induction of apoptosis of HL-60 cells. Methods: Apoptosis was detected by morphological observation and flow cytomertric cell cycle analysis. The expression of hTERT at mRNA and protein levels was analyzed by reverse transcriptase polymerase chain reaction (RT-PCR) and immunofluorescence using fluoresce isothiocyanate (FITC) label, respectively. Telomerase activity was determined by polymerase chain reaction enzyme-linked immunoassay (PCR-ELISA). Results: Treatment of 2 μmol/L at As2O3 could induce apoptosis of HL-60 cells. hTERT was decreased at both mRNA and protein levels during apoptosis of HL-60 cells. Telomerase activity of HL-60 cells was significantly inhibited. Conclusion: It is suggested that telomerase activity of HL-60 cells might be specifically inhibited by AS2O3 through the downregulation of hTERT gene expression.

The Influence of Curcumin on the Cell Cycle of HL-60 Cells and Contrast Study

The mechanisms of curcumin inhibiting the proliferation of HL-60 cells were investigated. Acute myeloid leukemic cell line HL-60 was studied by using cell culture, NBT reduction, SABC method measuring BrdU incorporation rate, FCM measuring DNA contents and TUNEL method determining apoptotic cell percentage. Curcumin inhibited proliferation of HL-60 cells in a dose- and time-dependent manner. When the HL-60 cells were treated with 25 μmol/L curcumin for 48 h, the inhibitory rate was 60. 71 % ± 1. 20 %. The study on BrdU incorporation rate and the distribution of DNA content and NBT reduction indicated that curcumin arrested. the cells in G2/M phase of cell cy cle at first, then in G0/G1 phase, the whole cell cycle progression was slowed down and DNA synthesis activities was halted. The arrested cells went to apoptosis instead of differentiation. The comparative study indicated that the ability of curcumin regulating the cell cycle of HL-60 cells was stronger than As2O3 and the acting points of curcumin were not completely consistent with those of VP-16. It was suggested that curcumin was able to regulate, to some extent, the G1/S and G2/M transmit checkpoints and disturb the HL-60 cell cycle to induce apoptosis.

Pyrrolidine Dithiocarbamate (PDTC) Attenuates Luteolin-Induced Apoptosis in Human Leukemia HL-60 Cells

Studies have indicated that flavonoid luteolin is a potential inhibitor of tumor cell proliferation and may function as an anticarcinogenic agent. Pyrrolidine dithiocarbamate (PDTC), a synthetic compound, may exhibit biphasic effects on apoptosis depending on the experimental context. Previously, we found that luteolin induced the activation of the proapoptotic proteins, such as Bad, Bid, and Bax, in HL-60 human leukemia cells. We also explored the modulatory effects and molecular mechanisms of PDTC on the cytotoxicity of luteolin in HL-60 cells;PDTC could interfere with luteolin’s ability to cleave poly(ADP-ribose)-polymerase (PARP) and DNA fragmentation of factor-45 (DFF-45). In the current study, we further investigated the effect of PDTC on the luteolin-induced death-receptor pathway and the cleavage of the Bcl-2 family members. We found that the combination of luteolin and PDTC increased the survival of the HL-60 cells such that PDTC inhibited both extrinsic and intrinsic pathways in luteolin-induced apoptosis.

EFFECTS OF S86019, AN ACTIVE COMPONENT FROM PURALIA LOB AT A, ON CELL DIFFERENTIATION AND CELL CYCLE TRAVERSE OF HL-60 CELLS

The effects of S86019, an active component from Puralia lobata, on the induction of cell differentiation and cell cycle traverse of HL-60 cells were described. It was shown that cell proliferation of HL-60 cells was inhibited by S86019 in vitro. Under the action of S86019 the HL-60 cells were induced to differentiate into metamyelocytes, myelocytes and much matured cells with banded or segmented nucleus. Flow cytometry demonstrated that the cell population of HL-60 cells was blocked at G1 phase which resulted in the elevation of percentage of G1 cells and decrease of percentage of cells in S phase. Experimental results demonstrated that S86019 is an active inducer of cell differentiation in HL-60 cells.

Effects of Concurrent Use of rh-IFN-γ and Curcumin on the Anti-proliferative Capacity of HL-60 Cells

To understand the effect of rh-IFN-γ on the ability of curcumin to kill HL-60 cells in vitro, the myeloid leukemic cell line HL-60 was studied by using cell culture. BrdU incorporation rate was examined by SABC, DNA content was determined by flow cytometry and apoptotic cell percentage was determined by TUNEL method. The results showed that curcumin inhibited proliferation of leukemic cells in a dose-dependent manner. When HL-60 cells were treated with 25 μmol curcumin for 24 h, the proliferative inhibitory rate was 43. 75±2. 00 %.This effect could be enhanced obviously by IFN-γ, the combined proliferative inhibitory rate increased to over 80 %. The 5-BrdU incorportion rate and the distribution of DNA content indicated that curcumin could arrest cells in the G1/G0 and G2/M phase of cell cycle. At the same time, the sub-G1 peak (apoptotic peak) appeared. After IFN-γ combined with curcumin, DNA synthesis rate decreased further. It showed a significant difference when compared with single drug group (Pr< 0. 05). Meanwhile, sub-G1 peak also increased. The percentage of TUNEL positive cells was aslo increased. It is concluded that IFN-γ can enhance the antiproliferative ability of curcumin against HL-60 cells.

Regulation of Histone Acetylation and Apoptosis by Trichostatin in HL-60 Cells

Summary: In order to examine the strong anticancer action and low toxicity of Trichostatin A (TSA), the effect of TSA was examined on the growth inhibition, acetylation of histone H_3 and apoptosis in HL-60 cells by employing MTT, immunocytochemical techniques, and Annexin-V-FITC/PI assay. Our results showed that TSA could inhibit proliferation of HL-60 cells in a time-and dose-dependent manner, and the IC_~50 at the 36th h was 100 ng/ml. The apoptosis-inducing effect of TSA on HL-60 cells was also time-and dose-dependent. But it didn't demonstrate apparent apoptosis induction in NPBMNCs within specific dose and time range. Both of the acetylation of histone H_3 in HL-60 cells and NPBMNCs increased significantly (P<0.05) after treated with 100 ng/ml TSA for 4 h. However, there was no significant differences between the two groups (P>0.05). It is concluded that TSA can inhibit growth and induce apoptosis of HL-60 cells in a time-and dose-dependent manner, and is able to selectively induce apoptosis in HL-60 cells but does not respond in NPBMNCs under the same conditions. The difference of TSA between HL-60 cells and NPBMNCs can't be explained by the regulation of histone acetylation.

EFFECTS OF THE HYPERTHERMIA AND HARRINGTONINE ON TELOMERASE ACTIVITY OF HL-60 CELLS

Objective To understand the mechanism of the hyperthermia and harringtonine in purging of leukemia cells In Vitro. telomerase activity of HL-60 cells treated by hyperthermia ( 42℃ for one hour) and different concentrations of Harringtonine were investigated.Methods Using Telomeric Repeats Amplification Protocol (TRAP) and ELISA techniques to analyze the telomerase activity of HL-60 cells. Results Our results showed that harringtonine inhibited the telomerase activity of HL-60 cells in a dosage related manner. Moreover, the telomerase activity of HL-60 cells was significantly decreased after the hyperthermia treatment as compared with untreated cells.Conclusion The effect of the hyperthermia and Harringtonine on purging leukemia cells In Vitro may be mediated by down regulation of telomerase activity of tumor cells.

Megadoses of Sodium Ascorbate Efficiently Kill HL60 Cells <i>in Vitro</i>: Comparison with Arsenic Trioxide

Arsenic Trioxide (ATO) is widely acknowledged as the treatment of choice for Acute Promyelocytic Leukemia (APL). It is a “two-sided” drug since it can induce differentiation or kill APL and other tumor cells according to the dosage. Part of the cytotoxic effects of ATO on APL cells is due to its pro-oxidant activity, a characteristic which ATO shares with a number of other compounds, including high doses of ascorbate (ASC). In a comparative investigation on the cytotoxic effects of both ATO and ASC on HL60 (APL) cell lines, in Vitro, we have been able to confirm the known cytotoxic effects of ATO, but, more importantly, we have demonstrated that ASC is significantly more effective than ATO, in killing these cancer cells in Vitro, when the concentrations are maintained within the millimolar (mM) range, i.e. the range of plasma concentrations at which ASC induces oxidative damage to tumor cells. Since these plasma levels can be reached only by the intravenous administration of high doses of ASC, we propose that intravenous high doses of ASC may represent a potentially revolutionary new approach in the management of APL.

EFFECTS OF ANTISENSE OLIGODEOXYNUCLEOTIDES ON EXPRESSION OF CASPASE-3 IN Γ-RADIATION INDUCED APOPTOTIC HL-60 CELLS

Objective To study the inhibitory effects of caspase-3 mRNA antisense oligodeoxynucleotides (ASODN) on expressions of caspase-3 and it's mRNA in γ-radiation induced apoptotic HL-60 cells, and screen the effective ASODN. Methods ASODN-1 and ASODN-2 targeting 5′-noncoding region and initial translation region of caspase-3 mRNA were respectively designed, synthesized and introduced into HL-60 cells by means of liposome-mediated transfection followed by 10Gy γ-radiation exposures. TUNEL assay was conducted to investigate the morphologic change and apoptotic percentage of HL-60 cells 18 h later. Immunocytochemical staining and one step RT-PCR were respectively performed to detect the expressions of caspase-3 and it's mRNA. Mismatched oligodeoxynucleotide (MODN) transfected and un-transfected HL-60 cells were taken as control. Results TUNEL assay found that the apoptotic percentages in ASODN-1 and ASODN-2 groups were significantly reduced compared with the control groups (P<0.01) when the final concentration of both ASODNs was ≥3μmol/L. Immunocytochemistry showed that caspase-3 positive cell percentages were reduced but the average gray values increased significantly compared with the control groups (P<0.01). RT-PCR showed expressions of caspase-3 mRNA was decreased after ASODN transfection. Furthermore, ASODN-1 proved more effective in inhibiting HL-60 cell apoptosis than ASODN-2 (P<0.01). Conclusion Caspase-3 mRNA ASODNs can prevent HL-60 cells from apoptosis induced by γ-radiation and reduce expression of caspase-3 and its mRNA. These effects are dose dependent in a certain range.

THE STUDIES OF REVERSAL ON INHIBITING DNA SYNTHESIS AND CLONAL FORMATION OF HL－60 CELLS WITH HYPERTHERMIA

It was confirmed that the damage of HL-60 cells caused by heating (42℃, 60min) was of heterogeueity.The partial recovery of colony survival and 3H-TdR incorporation from inhibited HL-60 cells was acquired through short-term (24h) Iiquid culture. The resultsindicated that inhibition of DNA synthesis and colonyformation of leukemic cells by hyperthermia was partlyreversible. Its clinical significance and pathogenicmechanism were also discussed.

Microcalorimetric Study of the Effect of Porphyrin－Cholesterol Esters on Cancer Cells HL－60

By using an LKB-2277 Bioactivity Monitor, the effect ofporphyrin-cholesterol esters on cancer cells RL-60 were examined at 25℃.There is a dirrerence in the shape of the thermogenesls curve samong different kinds or Porphyrln-cholesterol esters,and the death rate or HL-60 cells is also different. The results show that porphyrin-chsterol esters can powerfully inhibit their metabolism, the inhibitory sequence is Ⅱ >I >Ⅲ,but the inhibitory way of each ester is different.

Effect of Concurrent Use of rh-IL-3 and rh-GM-CSFon Apoptosis of HL-60 Cells Induced by Ara-C

The myeloid leukemic cell line HL-60 was studied by using DNA gel electrophoresis, flow cytomery, McAb C-myc, McAb Bc1-2 and CFU-L. From zero to 36 h,the apoptosis rates of 8 different phases and other indexes were observed. The results showed that with the prolonged time of drug incubation,apoptosis of HL-60 cells increased progressively. This effect can be enhanced obviously by rh-IL-3 and rh-GM-CSF. At the same time,the killed rate of leukemic cells by Ara-C induction was increased. C-myc expression was decreased and Bc1-2 expression did not display apparent change. Interestingly, the normal hemopoietic cells were not affected by these two kinds of cytokine. The theoretical basis was provided for concurrent use of rh-IL-3, rh-GM-CSF and cytotoxic drugs whose purpose is to elevate remission rate during the phase of induced remission of leukemia.

Effect of N’-Acetylindirubin on Proliferation, Apoptosis and Cell Cycle in Acute Myeloid Leukemia HL-60 Cells

Acute promyelocytic leukemia (APL) is a severe type of acute leukemia and the prognosis of patients was poor. Indirubin is the active constituent of the traditional Chinese medicine qingdai and an indoline anti-tumor drug. N’-Acetylindirubin is a novel indirubin derivative with better curative effect and less side effect. In this study, the effects of N’-Acetylindirubin on proliferation, apoptosis and cell cycle of acute myeloid leukemia cell line HL-60 was examined. The results demonstrated that N’-Acetylindirubin significantly induced apoptotic cell death in a dose and time-dependent manner and arrested cell cycle in G2/M in HL-60 cells. N’-Acetylindirubin also suppressed cyclin D1. This study suggests that N’-Acetylindirubin may serves as a potential chemopreventive agent for acute promyelocytic leukemia.

Antioxidant attenuation of ROS-involved cytotoxicity induced by Paraquat on HL-60 cells

The cytotoxic effects of Paraquat, an herbicide refractory to treatment after intentional or accidental contact, were investigated on the human leukemia HL-60 cells. With the establishment of Paraquat injury model of HL-60 cells, trypan blue exclusion assaying was performed to have determined the effects of Paraquat-induced cytotoxicity on HL-60 cells in a concentration- dependent manner. Upon treatment with various concentrations of Paraquat, pronounced increase on the levels of intracellular production of O2?- and H2O2 was detected with employment of fluorescent probes. Indicative of the oxidative stress, levels of MDA and T-AOC were quantitated to have determined the causal role for Paraquat in subjecting HL-60 cells to oxidative damage. Based on this finding, effects of antioxidant enzymes including GSH, NAC, CAT and SOD on attenuating the Paraquat-induced oxidative damage on HL-60 cells were examined, aiming to identify the most effective antioxidant enzyme for alleviating the cytotoxicity induced by Paraquat. In conjunction with the determination of cytotoxicity exerted by all the antioxidant enzymes on HL-60 cells, GSH-with its least inherent cytotoxicity on HL-60 cells-was identified as a promising candidate ingredient for extenuating the Paraquat-induced cytotoxicity.

1-Chloromethyl-6,7-dimethoxy-3,4-dihydro-1H-isoquinoline-2-sulfonic acid amide, a derivative of tetrahydroisoquinoline, induces granulocytic differentiation of the human leukemic HL-60 cells via G0/G1 phase arrest

Tetrahydroisoquinolines are known to have various biological effects, including antitumor activity. This study investigated the effect of 1-chloromethyl-6, 7-dimethoxy-3, 4-dihydro-1H-isoquinoline-2-sulfonic acid amide (CDST), a newly synthesized anticancer agent, on cellular differentiation and proliferation in HL-60 cells. Differentiation and proliferation of HL-60 cells were determined through expression of CD11b and CD14 surface antigens using flow cytometry and nitroblue tetrazolium (NBT) assay, and through analysis of cell cycle using propidium iodide staining, western blot analysis and immunoprecipitation, respectively. CDST induced the differentiation of HL-60, as shown by increased expression of differentiation surface antigen CD11b (but no significant change in CD14 expression) and increased NBT-reducing functional activity. DNA flow cytometry analysis indicated that CDST markedly induced a G0/G1 phase arrest of HL-60 cells. Subsequently, we examined the expre-ssion of G0/G1 phase cell cycle-related proteins, including cyclin-dependent kinases (CDKs), cyclins and cyclin dependent kinase inhibitors (CKIs), during the differentiation of HL-60. The levels of CDK2, CDK6, cyclin E and cyclin A were decreased, whereas steady-state levels of CDK4 and cyclin D1 were unaffected. The expression of the p27Kip1 was markedly increased by CDST, but not p21WAF1/Cip1. Moreover, CDST markedly enhanced the binding of p27Kip1 with CDK2 and CDK6, resulting in the reduced activity of both kinases. Taken together, these results demonstrate that CDST is capable of inducing cellular differentiation and growth inhibition through p27Kip1 protein-related G0/G1 phase arrest in HL-60 cells.