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

This study was aimed to compare the influences of bone marrow mesenchymal stem cells (BMMSCs) from patients with acute myeloid leukemia (AML), AML patients with complete remission (CR) and non-leukemia patients on HL-60 cells. The HL-60 cells were divided into three groups: group of co-cultivation with BMMSCs of AML patients, group of co-cultivation with BMMSCs of AML patients with CR and group of co-cultivation with BMMSCs of non-leukemia patients. The count of HL-60 cells, the CD11b and survivin expression of HL-60 cells, the cell cycle distribution of the HL-60 cells in 3 groups were compared by flow cytometry, the morphology and differentiation rate of HL-60 cells in 3 groups were observed and compared by microscopy. The results showed that there were no differences in HL-60 cell count at five and seven days, in HL-60 distribution at the G(0)/G(1) phase, in survivin and CD 11b expressions in 3 groups. All cells of 3 groups began to mature, and the differentiation rates in 3 groups were 18.0 +/- 3, 17.0 +/- 1.3 and 19.0 +/- 2.0 respectively, therefore there were no significant differences between the 3 groups (p = 0.23). It is concluded that there is no influence of BMMSCs in 3 groups on the proliferation and differentiation of HL-60 cells.
Bone Marrow Cells ; cytology ; Cell Differentiation ; Cell Proliferation ; Coculture Techniques ; HL-60 Cells ; Humans ; Leukemia ; pathology ; Mesenchymal Stromal Cells ; cytology

To investigate the effect of a microsomal prostaglandin E synthase-1 (mPGES-1) inhibitor MK886 on cell cycle of the human acute myeloid leukemia HL-60 cells. HL-60 cells were treated with different concentration of MK886 (10, 25, 50 µmol/L) for 24 h. Flow cytometry, Western blot and ELISA were used to measure cell cycle, cyclin D1, mPGES-1, PGE(2), Akt, P-Akt and C-MYC. The results indicated that after treated with MK886, the percentage of HL-60 cells decreased in G(0)/G(1) phase and increased in S phase, and expressions of mPGES-1, cyclin D1, P-Akt and C-MYC and synthesis of PGE(2) decreased significantly. It is concluded that MK886 can arrest HL-60 cells in G(0)/G(1) phase, the mechanism of which is possibly associated to inhibition of mPGES-1 expression, reduction of PGE(2) synthesis, suppression of Akt phosphorylation and C-MYC expression, down-regulation of cyclin D1 expression.
Cell Cycle ; drug effects ; HL-60 Cells ; Humans ; Indoles ; pharmacology ; Intramolecular Oxidoreductases ; antagonists & inhibitors ; Leukemia ; metabolism ; pathology ; Prostaglandin-E Synthases

OBJECTIVETo study the effect of reactive oxygen species (ROS) during the leukemogenic process associated with exposure to benzene.

METHODSHL-60 was treated with 3 micromol/L benzoquinone (BQ). Generation of ROS in cells was measured by DCFH-DA method. For proliferation assays,cells were stained with alamar blue dye and counted.

RESULTSROS production and the proliferation of cell were all increased in BQ-treated cells (13.10 +/- 0.15, 185% +/- 30.00%) as compared with control cells (11.32 +/- 0.09, 100% +/- 0.00%) (P < 0.05); The addition of catalase just before BQ addition reduced ROS generation to basal levels and decreased the growth of cell (P < 0.05).

CONCLUSIONROS may play an important role in the process of proliferation of HL-60 cells induced by BQ.

Benzoquinones ; toxicity ; Cell Proliferation ; drug effects ; HL-60 Cells ; drug effects ; metabolism ; pathology ; Humans ; Reactive Oxygen Species ; metabolism

OBJECTIVETo explore whether daunorubicin (DNR) combined with cytosine arabinoside (Ara-C) and DNR alone have similar effect on acute promyelocytic leukemia (APL) cell line NB4 and acute myeloblastic leukemia cell line HL-60 in vitro.

METHODSCell morphology, cells viability, and cell apoptosis (Annexin-V by flow cytometry assay) were analysed.

RESULTSAfter incubation with DNR plus Ara-C for 24 hours,NB4 cell viability [(36.75 +/- 3.82)%] (n = 6) and cell apoptosis rate [(21.24 +/- 5.82)%] (n = 3) did not change significantly compared to that treated with DNR alone for 24 hours [(35.73 + 6.28 )%, (22.55 +/- 3.26)%, respectively] (P > 0.05). However, HL-60 cell viability [(67.17 +/- 2.07)%] and cell apoptosis rate [(48.05 +/- 0.92)%] changed significantly in DNR plus Ara-C group compared with DNR alone [(63.31 +/- 1.80)% ,(41.51 +/- 0.89)%, respectively] (P < 0.01 and < 0.05, respectively).

CONCLUSIONDNR plus Ara-C and DNR alone have similar effect on NB4 cells, but have different effect on HL-60 cells.

Apoptosis ; drug effects ; Cytarabine ; pharmacology ; Daunorubicin ; pharmacology ; HL-60 Cells ; drug effects ; Humans ; Leukemia, Promyelocytic, Acute ; pathology

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

The purpose of this study was to investigate the expression feature of a human tumor related gene chp2 in leukemia primary cells and leukemia cell lines, real-time quantitative PCR (RQ-PCR) was performed to detect the expression level of chp2 gene in peripheral blood mononuclear cells from 10 healthy individuals (as control) and 24 cases of leukemia, and in 4 kinds of leukemia cell lines. The results showed that the detection rate of chp2 gene in 10 normal controls was 80%, positive expression was (0.744 +/- 0.682) x 10(5) cps/microl. The expression levels of chp2 mRNA leukemia primary cells and leukemia cell lines were significantly higher than that in the normal control (p < 0.05). The expression levels of chp2 mRNA were higher in AML cells (7 cases), CML cells (6 cases), ALL cells (7 cases) and CLL cells (4 cases), and their expression levels were (11.637 +/- 5.588), (6.122 +/- 3.785), (4.262 +/- 2.561) and (3.434 +/- 1.974) x 10(5) cps/microl respectively. Gene chp2 positively expressed in four kinds of leukemia cell lines, and the expression levels in K562 cells, Jurkat cells, HL-60 cells and M07e cells were (5.243 +/- 1.852), (4.463 +/- 1.621), (4.137 +/- 1.837) and (2.578 +/- 1.137) x 10(6) cps/microl respectively. The expression level in leukemia cell lines was higher than that in primary cells. It is concluded that the human tumor related gene chp2 expression in leukemia primary cells and leukemia cell lines significantly increase, which may play an important role in growth process of leukemia cells.
Calcium-Binding Proteins ; genetics ; metabolism ; HL-60 Cells ; Humans ; Jurkat Cells ; K562 Cells ; Leukemia ; genetics ; metabolism ; pathology ; Neoplasm Proteins ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism

OBJECTIVETo observe the effect of leukemic cells on blood-brain barrier (BBB) in mice with central nervous system leukemia (CNSL) by establishing mice CNSL model and an in vitro BBB model and explore the mechanism of leukemic cell infiltrating central nervous system (CNS).

METHODSAfter splenectomy, cytoxan intraperitoneal injection, and sublethal irradiation, 10 BALB/c nu/nu mice were transplanted intravenously with 1.2 × 10(7) of SHI-1 human monocytic leukemic cells. Mice were monitored for survival and clinical manifestation of nerve palsy. The leukemic cells engrafted were examined by RT-PCR, histopathology and bone marrow (BM) smears. Immunofluorescence analysis with laser scanning fluorescence confocal microscopy was used to determine the expression of fibrinogen and tight-junction protein ZO-1. An in vitro BBB model composed of human brain microvascular endothelial cells (BMVECs) was developed on a Matrigel-based insert. Different leukemic cell lines were seeded onto the upper compartment of transwell insert. After incubated for 24 h with BMVECs, cells that had migrated into the lower compartment were counted and analyzed.

RESULTS(1) Paralysis with or without sight loss was developed in half the mice 30-35 d after innoculated with SHI-1 cells. Leukemic cells infiltrates were observed in BM and in different part of brain tissues including brain parenchyma. The transcriptions of human MLL/AF6 fusion gene were also detected in BM and brain tissues in paralysis mice. The fibrinogen expression and ZO-1 disruption were detected in the infiltrated tissue. (2) After 24 h incubation with leukemic cells, the BMVECs sheets were disrupted and grew singly and ZO-1 expression was down-regulated markedly. SHI-1 cells showed more injurious to BMVECs and higher invasive rate \[(40.33 ± 1.53)% vs (11.83 ± 1.44)%, P < 0.05\] than HL-60 cells did.

CONCLUSIONOne of the mechanisms of leukemic cells infiltrates CNS in CNSL is injure to the BBB.

Animals ; Blood-Brain Barrier ; physiology ; Central Nervous System ; pathology ; Central Nervous System Neoplasms ; pathology ; HL-60 Cells ; Humans ; Leukemia ; pathology ; Mice ; Mice, Inbred BALB C ; Mice, Nude

Increasing attention has been focused on the antitumor activity of artemisinin derivatives in recent years, for artemisinin had been reported to have cytotoxic effects against HL-60, P388 and MCF-7 tumor cells. We report here the synthesis and evaluation for antitumor activity of a series of artemisinin-ether derivatives bearing tetrahydropyrrole, morpholine, piperidine, substituted piperidines and azoles with various linkers. Sixteen 10-O-substituted dihydroartemisinin derivatives were designed and synthesized, all of which have never been reported in literatures and whose antiproliferative effects on human breast cancer MCF-7, MCF-7/Adr and HL-60 cells were determined by MTT assay or direct cell counting. Each of these artemisinin derivatives possessed better effects than dihydroartemisinin evidently against HL-60 and MCF-7 cells growth, while less potent than doxorubicin. All target compounds exhibited significantly improved potency compared to DHA and doxorubicin on the doxorubicin-resistant MCF-7/Adr cells, so did they in their sensitive counterparts MCF-7 cells. Among them, compounds GF02, GH04 and ZH04 showed strong activity against these three cell lines growth. Further research is undergoing.
Antineoplastic Agents ; chemical synthesis ; chemistry ; Artemisinins ; chemical synthesis ; chemistry ; Breast Neoplasms ; pathology ; Cell Proliferation ; Doxorubicin ; Drug Design ; HL-60 Cells ; drug effects ; Humans ; MCF-7 Cells ; drug effects

OBJECTIVETo explore ZO-1 gene expression and methylation in leukemia cells and the involvement of ZO-1 gene in leukemogenesis.

METHODSRestriction landmark genomic scanning (RLGS) was used to identify new leukemia related gene, and methylation specific PCR (MSP) for ZO-1 methylation status. ZO-1 specific siRNA was designed and prepared by in vitro transcription and transfected into K562 cells, the transfected cells were cultured for 48 hours before harvesting. The effect of ZO-1 siRNA was monitored by Northern blot. Cellular proliferation capacity was assayed by CCK-8, cell apoptosis by Annexin V-fluorescence in isothiocyanate (FITC) assay, and cell cycle by phosphatidylinositol (PI).

RESULTSThe intensified spots in RLGS gel were subjected to bioinformatics analysis and one of the candidate spots was proved to be ZO-1 gene. In fresh leukemia cells, Molt4 cells and HL-60 cells, ZO-1 was hypermethylated, causing it reduced or silenced. ZO-1 gene was highly expressed with no methylation in normal peripheral blood MNC and K562 cells. There was a good correlation between promoter methylation and the gene silence. The silenced gene can be re-activated by demethylation treatment with 5-AZA-dC in most leukemia cell lines. RNA interference for ZO-1 gene in K562 cells did not interfere with cell proliferation, cell cycle and apoptosis.

CONCLUSIONZO-1 gene methylation might be involved in the tumorigenesis of acute leukemia.

Animals ; DNA Methylation ; HL-60 Cells ; Humans ; K562 Cells ; Leukemia ; genetics ; pathology ; Membrane Proteins ; genetics ; metabolism ; Mice ; Phosphoproteins ; genetics ; metabolism ; Zonula Occludens-1 Protein