Tetrandrine induces autophagy and differentiation by activating ROS and Notch1 signaling in leukemia cells

All-trans retinoic acid (ATRA) is a differentiating agent for the treatment of acute promyelocytic leukemia (APL). However, the therapeutic efficacy of ATRA has limitations. Tetrandrine is a traditional Chinese medicinal herb extract with antitumor effects. In this study, we investigated the effects of tetrandrine on human PML-RARα-positive acute promyelocytic leukemia cells. Tetrandrine inhibited tumors in vivo. It induced autophagy and differentiation by triggering ROS generation and activating Notch1 signaling. Tetrandrine induced autophagy and differentiation in M5 type patient primary leukemia cells. The in vivo results indicated that low concentrations of tetrandrine inhibited leukemia cells proliferation and induced autophagy and then facilitated their differentiation, by activating ROS and Notch1 signaling. We suggest that tetrandrine is a potential agent for the treatment of APL by inducing differentiation of leukemia cells.     

Hyperthermia induces differentiation without apoptosis in permissive temperatures in human erythroleukaemia cells

Purpose: The aim of the present study was to investigate whether induction of differentiation by hyperthermia is accompanied by apoptosis and necrosis to further evaluate the benefits of using hyperthermia as a differentiation inducing physical modality.

Materials and method: Differentiation was evaluated in K562 erythroleukaemia cells by measuring haemoglobin synthesis and flow cytometric measurement of glycophorin A expression. Apoptosis was measured by Annexin-V-FITC and Propidium Iodide (PI) double staining assay. Apoptosis and necrosis was also evaluated morphologically using staining with acridine orange/ethidium bromide (AO/EtBr) by fluorescence microscopy. Heat shock protein 70 (HSP70) level was measured by ELISA kit.

Results: Hyperthermia (43°C) induced differentiation as judged by increased haemoglobin synthesis and glycophorin A expression. No sign of apoptosis or necrosis could be detected at this temperature. Cell viability did not change due to heat treatment, and cellular proliferation was reduced in a dose (heating time) dependent manner. At 45°C, hyperthermia induced apoptosis and necrosis with minimal or no sign of differentiation. HSP70 level was significantly increased at 43°C along with differentiation of leukaemic cells, while at 45°C no significant effect on HSP70 production could be observed.

Conclusions: The encouraging results obtained here indicate that by heat treatment at 43°C, hyperthermia can be used alone or in combination with other modalities as a differentiation inducing agent without any detectable apoptotic activity. Positive correlation between HSP70 production and induction of differentiation and lack of apoptosis by hyperthermia confirm the possible role of HSP70 in the heat-induced differentiation and apoptosis in leukaemic cells.     

Triple combination of retinoic acid + low concentration of cytosine arabinoside + hexamethylene bisacetamide induces differentiation of human AML blasts in primary culture

Differentiation induction therapy provides an alternative therapeutic approach for patients with acute myeloid leukemia (AML) who are either unsuitable for or unresponsive to conventional cytotoxic chemotherapy. The effect of a triple combination of retinoic acid (RA) + low concentration of cytosine arabinoside (Ara-C) + hexamethylene bisacetamide (HMBA) on differentiation of blasts from 24 AML patients was studied. Non-adherent mononuclear cells were seeded at a concentration of 5 x 10(5) cells per ml in 24-well tissue culture plates containing RPMI 1640 culture medium with 20 per cent fetal calf serum and 10 per cent 5637-conditioned medium and incubated with 10(-6) M retinoic acid, 10(-6) M cytosine arabinoside and/or 2 mM hexamethylene bisacetamide for six days at 37 degrees C in a humidified incubator under 5 per cent CO2. Morphological, cytochemical and functional differentiation into mature cells were induced in blasts from 22 out of the 24 AML patients following exposure to the triple combination of 10(-6) M RA + 10(-6)M Ara-C + 2 mM HMBA in primary culture. These effective results justify a clinical trial of such triple combination for AML patients who are either unsuitable for or unresponsive to conventional cytotoxic chemotherapy.     

Alteration of polypeptide synthesis and composition during differentiation of human leukemia cell line HL60

Using two-dimensional gel electrophoresis, we have analyzed the polypeptide alteration of the human myeloid leukemia cell line HL60 during differentiation induced by dimethylsulfoxide (DMSO) and 12-O-tetradecanoylphorbol-13-acetate (TPA). Three polypeptides increased in synthesis after DMSO treatment, while 5 polypeptides increased after TPA treatment. Most other polypeptides were synthesized at a reduced rate though their net amounts remained unchanged, indicating that myeloid differentiation was associated not only with an increased synthesis of a few specific polypeptides but also with overall depression of most other polypeptides. One of the early differentiation marker proteins (mol. wt approx. 20,000, pl approx. 6.0) of granulopoietic cells was increased specifically after DMSO treatment, while one of the monocyte specific marker proteins (mol. wt approx. 46,000, pl approx. 4.8) was detected after TPA treatment. But, the pattern of HL60 cells did not necessarily become similar to that of normal mature granulocytes after DMSO treatment, indicating that HL60 cell differentiation might be partial or incomplete.     

Cell differentiation and therapeutic effect of low doses of cytosine arabinoside in human myeloid leukemia

Bone marrow cells from 2 patients over 60 years of age with acute myeloblastic (AML) of monoblastic (AMoL) leukemia were cultured in the presence of a low dose of cytosine arabinoside. In the cells from the AML patient this treatment induced differentiation to metamyelocytes and a decrease in the number of blasts, so that there was an 11 -fold increase in the ratio of differentiated myeloid cells to blasts. In the patient with AMoL there was differentiation to monocytes and macrophages and only a 3-fold increase in the ratio of differentiated myeloid cells to blasts. In the latter patient actinomycin D was a more potent inducer of differentiation than cytosine arabinoside, daunomycin was similar to cytosine arabinoside and adriamycin showed the lowest response. Four courses of low dose treatment with cytosine arabinoside produced remission in the patient with AML and in another patient with AMoL whose cells were not tested in culture. No remission was induced by this low dose treatment in the patient with AMoL whose cells showed only a small decrease in blast cells in culture with cytosine arabinoside. It is suggested that prescreening for effective compounds in patients with myeloid leukemias and the use of low dose therapy can be of help in obtaining remission without serious side effects. This could be especially useful in patients where there may be severe toxic effects after high dose chemotherapy.     

骨髓成纤维样基质细胞系对急性髓细胞白血病细胞系增殖与分化影响的研究

目的：以急性髓细胞白血病（acute myeloid leukaemia,AML）细胞系为研究对象,观察正常人骨髓成纤维样细胞系（human bone marrow fibro—blastoid stromal cell line,HFCL）对急性单核细胞白血病细胞系U937、急性粒细胞白血病敏感细胞HL-60和多药耐药细胞HL-60／VCR增殖和分化的影响。方法：建立U937、HL-60和HL-60／VCR细胞与HFCL细胞的共培养模型,实验分对照组、直接接触组和transwell组。采用台盼蓝拒染法测定生长曲线;硝基四氮唑蓝（NBT）确定细胞分化;流式细胞仪检测细胞周期和CD11b、CD13、CD14和CD33细胞表面抗原进一步鉴定细胞分化;west-ernblot检测增殖细胞核抗原（PCNA）和P-糖蛋白（P-gP）的表达。结果：与HFCL细胞共培养96h后,U937、HL-60和HL-60／VCR细胞的生长受抑,且与HFCL细胞直接接触组的抑制作用大于用tr-answell组,P〈0．01。同时发现AML细胞系与HFCL细胞共培养后,G0／G1期细胞比例均增高,而S期细胞均减少,P〈0．01;尤其是直接接触组CD11b和CD14表达也均增高（P〈0．01）,CD13和CD33变化不大,NBT阳性细胞轻度增高,且差异有统计学意义。Western blot检测结果显示,3种AML细胞系PCNA表达下调;以直接接触组为甚。提示介导着白血病细胞和骨髓基质细胞间的相互作用的整合素p1（VLA-4）和p2（LFA-1）,在HFCL细胞对AML细胞生长作用影响中起着不可忽视的作用。结论：HFCL对3种具有代表性的AML细胞系U937、HL-60和HL-60／VCR有增殖抑制和诱导分化作用,除了能抑制AML细胞的生长,抑制PCNA的表达,出现G0／G1期阻滞外,还能诱导其部分向单核细胞分化。     

Induction of cell differentiation in human leukemia U-937 cells by 5-oxygenated-6,7-methylenedioxycoumarins from Pterocaulon polystachyum

The present study focused on the effect of a series of extracts and two 5,6,7-trioxygenated coumarins isolated from Pterocaulon polystachyum on the proliferation and differentiation of human promonocytic U-937 cells. The petroleum ether extract was the only extract that significantly reduced cell proliferation and induced cell differentiation. Treatment with pure 5-methoxy-6,7-methylenedioxycoumarin (C1) and 5-(3-methyl-2-butenyloxy)-6,7-methylenedioxycoumarin (C2), present in the petroleum ether extract, showed a time and concentration-dependent inhibition on cell proliferation. In addition, the coumarin derivatives were also able to induce CD88 functionality and NBT reduction, markers of monocytic cell differentiation.

These results suggest that C1 and C2 might have a potential therapeutic role in the management of leukemia.     

Screening for induction of differentiation and toxicity to blast cells by chemotherapeutic compounds in human myeloid leukemia

Bone marrow cells from 9 patients with acute myeloid leukemia and 1 patient with a blast crisis of chronic myeloid leukemia were cultured to determine their ability to be induced to differentiate by different chemotherapeutic compounds. Five of these 10 patients showed differentiation to granulocytic and/or monocytic cells by culture with medium containing the myeloid cell differentiation-inducing protein MGI-2. Actinomycin D induced differentiation in cells from 2 of the patients who did not show differentiation with MGI-2 containing medium. In these 7 patients there was an increase in the ratio of differentiated myeloid cells to blasts. None of these 10 patients showed induction of differentiation by cytosine arabinoside, adriamycin, or daunomycin, but treatment with these compounds showed in some patients an increase in the ratio of differentiated myeloid cells to blasts. The results indicate that this ratio can be increased by differentiation and also in some patients by toxicity to blast cells. With dexamethasone or vinblastine there was no induction of differentiation and no increase in this ratio in any of the 10 patients tested. After in vivo chemotherapy with low dose cytosine arabinoside, cells from one patient showed a similar response in culture to actinomycin D as cells before chemotherapy, whereas in another patient the cells had acquired the ability to respond to actinomycin D. In contrast, after high-dose in vivo chemotherapy with cytosine arabinoside and daunomycin, cells from a third patient seemed to have lost the ability to differentiate in vitro by MGI-2 containing medium or actinomycin D. The results indicate that pre-screening for differentiation-inducing compounds and compounds that show toxicity to blast cells should be useful to select the appropriate compounds to be used for therapy, and that it is advisable to screen the cells both before and after initiation of therapy.     

K562 human leukemia cell passages differ in embryonic globin gene expression

K562 is a human leukemia cell line inductible by a variety of agents for the synthesis of embryonic and fetal hemoglobins. We compared early and late passages to determine whether a change has occurred in globin synthetic pattern. Clone LA4, derived from passage 199 which had been frozen by Lozzio in 1973, was compared with clone RA6, derived from a line received from Rutherford in 1979. Globin synthetic pattern was determined by incubation with [³]leucine, separation of globins by Triton-X100 polyacrylamide gel electrophoresis, and analysis by fluorography. For RA6, hemin-induced synthesis was greatest for zeta globin but minimal for epsilon globin, whereas for LA4 it was greatest for epsilon globin but minimal for zeta globin. Both lines are pseudotriploid with three No. 11 and three No. 16 chromosomes. However only RA6 has a translocation involving the short arm of chromosome 11 which contains the locus of the beta globin gene cluster. However, translocation-associated deletion does not simply explain the deficient inducibility of epsilon synthesis because ^Gγ and ^Aγ globins, whose genes are linked to the epsilon gene, are similarly inducible in the two lines.     

Diosgenin induces cell cycle arrest and apoptosis in human leukemia K562 cells with the disruption of Ca2+ homeostasis

Purpose Diosgenin is a steroidal sapogenin with estrogenic and antitumor properties. In order to elucidate the mechanism of its antiproliferative activity, we investigated its effects on the cell cycle and apoptosis in human chronic myelogenous leukemia K562 cells.Methods Cell viability was assessed via an MTT assay. Apoptosis was investigated in terms of nuclear morphology, DNA fragmentation, and phosphatidylserine externalization. Cell cycle analysis was performed via PI staining and flow cytometry (FCM). Western blotting and immunofluorescence methods were used to determine the levels of p53, cell cycle-related proteins and Bcl-2 family members. FCM was also used to estimate the changes in mitochondrial membrane potential (MMP), intracellular Ca²⁺ concentration and reactive oxygen species (ROS) generation.Results Cell cycle analysis showed that diosgenin caused G₂/M arrest independently of p53. The levels of cyclin B1 and p21^Cip1/Waf1 were decreased, whereas cdc2 levels were increased. Subsequent apoptosis was demonstrated with the dramatic activation of caspase-3. A dramatic decline in intracellular Ca²⁺ concentration was observed as an initiating event in the process of cell cycle arrest and apoptosis, which was followed by the hyperpolarization and depolarization of MMP. Generation of ROS was observed in the progression of apoptosis. The antiapoptotic Bcl-2 and Bcl-x_L proteins were downregulated, whereas the proapoptotic Bax was upregulated.Conclusions Diosgenin inhibits K562 cell proliferation via cell cycle G₂/M arrest and apoptosis, with disruption of Ca²⁺ homeostasis and mitochondrial dysfunction playing vital roles.     

A new leukemia cell line with Philadelphia chromosome characterized as basophil precursors

A new myeloid cell line (KU812) was established from a patient with blastic crisis of chronic myelogenous leukemia. His blasts were morphologically characteristic of immature basophils and basophil colonies were grown in agar culture of the blood mononuclear cells. Suspension culture of his blood cells was continued for more than 2.5 years. The KU812 cells morphologically showed a fine reticular nuclei with nucleoli, and some of them contained metachromatic granules with toluidine blue (TB) staining. These granules were positive for astra blue (AB) staining. Immunological marker studies revealed that there were no lymphoid characters except Fc receptors. The KU812 cells grew colonies in in vitro agar cultures, which were proved to be composed of basophils by TB staining and AB staining. Cytogenetical analysis showed marked aneuploidy and was positive for the Philadelphia chromosome (Ph1). The cell lysate was proved to contain histamine. These data suggest that KU812 is a cell line from leukemic basophil precursors. This is the first human basophil cell line, and KU812 will be useful in clarifying the mechanism of basophilic differentiation of the stem cells.     

Differentiation-associated changes in human non-T, non-B leukemia cell lines after treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA)

The ability of TPA to induce stable phenotypic changes that normally serve as markers of differentiation was examined in the four human non-T, non-B cell lines, NALL-1, NALM-16, REH and KM-3. In all four lines, noncytotoxic concentrations of the phorbol ester caused an extensive reduction in the number of cells expressing cALL surface antigen and terminal deoxynucleotidyl transferase. The disappearance of these markers correlated with the loss of cell proliferation. In one of the cell lines, NALL-1, TPA treatment gave rise to a significant increase in Ia-like antigen and antigen T-101, markers which represent more advanced stages of cell maturation. However, surface or cytoplasmic immunoglobins, indicators of mature B cells, were not detectable. Antigen 3A1, specific for myeloid and for T cells, antigen Leu-4, specific for T cells and antigen CM1, specific for monocytes, were also absent. In all cell lines, exposure to TPA resulted in an approximately two-fold increase in acid phosphatase and beta-glucuronidase activity. The emergence of these phenotype changes was not altered upon repeated washing of the TPA-treated cells. These results demonstrate that while TPA is capable of inducing various non-T, non-B cell lines to differentiate to a limited degree, differences exist between the lines in the extent to which they can mature towards the B-cell stage.     

Antiproliferative and proapoptotic effects of a pyrrole containing arylthioindole in human Jurkat leukemia cell line and multidrug-resistant Jurkat/A4 cells

Recently, a series of novel arylthioindole compounds, potent inhibitors of tubulin polymerization and cancer cell growth, were synthesized. In the present study the effects of 2-(1H-pyrrol-3-yl)-3-((3,4,5-trimethoxyphenyl)thio)-1H-indole (ATI5 compound) on cell proliferation, cell cycle progression, and induction of apoptosis in human T-cell acute leukemia Jurkat cells and their multidrug resistant Jurkat/A4 subline were investigated. Treatment of the Jurkat cells with the ATI5 compound for 48 hrs resulted in a strong G₂/M cell cycle arrest and p53-independent apoptotic cell death accompanied by the induction of the active form of caspase-3 and poly(ADP-ribose) polymerase-1 (PARP-1) cleavage. ATI5 treatment also caused non-cell death related mitotic arrest in multidrug resistant Jurkat/A4 cells after 48 hrs of treatment suggesting promising opportunities for the further design of pyrrole-containing ATI compounds as anticancer agents. Cell death resistance of Jurkat/A4 cells to ATI5 compound was associated with alterations in the expression of pro-survival and anti-apoptotic protein-coding and microRNA genes. More importantly, findings showing that ATI5 treatment induced p53-independent apoptosis are of great importance from a therapeutic point of view since p53 mutations are common genetic alterations in human neoplasms.     

A novel Ph1 chromosome positive cell line established from a patient with chronic myelogenous leukemia in blastic crisis

A novel Philadelphia (Ph1) chromosome positive cell line, designated KYO-1, was established from the peripheral blood of a patient with chronic myelogenous leukemia (CML) in blastic crisis. Although this line had a unique capacity to differentiate spontaneously along the erythroid and monocytoid lineages as evidenced by cytochemical analysis for the first several months, the capacity was gradually lost after repeated passages. The results suggest that KYO-1 is an undifferentiated myeloid cell line. This cell line provides a useful source for studying differentiation and proliferation of pluripotent stem cells from CML in blastic crisis.