A cytotoxic constituent fromSophora flavescens

A cytotoxic constituent was isolated by bioassay-guided procedure from the roots ofSophora flavescens Aiton (Leguminosae). The constituent was identified as sophoraflavanone G (I) by means of chemical methods and in comparsion with spectral data of standard compound. The ED₅₀ values of constituent I were 0.78, 1.57, 2.14 and 8.59 μg/ml against A549, HeLa, K562 and L1210 cell lines respectively. ConstituentI exhibited highly cytotoxic activities against A 549, K562 and HeLa cells, but showed a mild activity (ED₅₀ value, 5 μg/ml) against L1210 cells. Among the tested cell lines, A549 cells were the most sensitive to constituentI.     

Antitumor and antiangiogenic effects of GA-13315, a gibberellin derivative

This study showed that 13-chlorine-3,15-dioxy-gibberellic acid methyl ester (GA-13315), a gibberellin derivative, possessed high antitumor and antiangiogenic activity in vitro and in vivo. Cytotoxicity assays showed that GA-13315 was a potential and efficient antitumor compound, with inhibitory concentration 50 (IC₅₀) values ranging from 0.13 to 30.28 μg/ml in 12 human tumor cell lines, and it showed moderate toxicity to peripheral blood mononuclear cells with an IC₅₀ value of 14.2 μg/ml. Administration of 0.5 or 2.5 mg/kg GA-13315 for 23 days significantly inhibited tumor growth of human non-small cell lung tumor (A549) xenografts, with relative growth rates ranging from 29.91% to 35.05%. Acute toxicity was determined in ICR mice, and the lethal dose 50 (LD₅₀) was 4.19 g/kg after intragastric administration. The high antitumor potency of GA-13315 occurred in parallel with its antiangiogenic activity. In vitro, GA-13315 inhibited recombinant human epithelial growth factor-induced chemotactic motility and capillary-like tube formation of primary cultured human endothelial cells. Furthermore, GA-13315 decreased the factor VIII⁺ microvessel density and vascular endothelial growth factor expression in A549 tumors, indicating its antiangiogenic efficacy in vivo. These results indicate that the antiangiogenic activity of GA-13315 contributes to its anticancer properties. Further studies are needed to investigate the use of GA-13315 as an anticancer drug.     

Synthesis and biological evaluation of cyclopenten-1-one Mannich base oxovanadium compound

2-Hydroxy-3-methyl-2-cyclopenten-1-one Mannich base oxovanadium compound (CPD-VO) was synthesized. The human cancer cell lines SMMC-7721 (liver cancer) and SK-OV-3 (ovary cancer) were tested for their viability by MTT in vitro, which showed that CPD-VO exhibited a remarkable activity against the two cell lines, with IC₅₀ values <0.1 8 and <0.23 μg/ml, respectively. And clonogenic assays showed that CPD-VO at 6.250 μg/ml inhibited colony formation of SMMC-7721 cells by 99.10%. Also, CPD-VO suppressed tumor growth of Hep-A-22 (mouse liver cancer) in mice in vivo. Moreover, the interaction of CPD-VO with λ-DNA was investigated using UV–vis spectroscopy and viscosity. The results showed that CPD-VO was intercalated into the double-helix of λ-DNA. In flow cytometry analysis, the ratio of apoptotic cells was up to 8.15% after treatment with CPD-VO at 2.34 μg/ml after 30 min, suggesting that the antitumoral activity of CPD-VO came from activation of the apoptotic pathway. CPD-VO is a promising antitumoral agent.     

Pomolic acid-induced apoptosis in cells from patients with chronic myeloid leukemia exhibiting different drug resistance profile

Summary Pomolic acid (PA) is a pentacyclic triterpene which has been previously described as active in inhibiting the growth of K562 cell line—originated from chronic myeloid leukemia (CML) in blast crisis—and its vincristine-resistant derivative K562-Lucena1. In this work, cells from CML patients were treated with PA and the apoptotic index was compared with the multidrug resistance (MDR) profile and clinical status of the patients. Our findings show that PA 12.5 μg/ml at 24 h (p = 0.000), at 48 h (p = 0.012) and at 72 h (p = 0.005) has a potent apoptotic index in CML cells as compared to mononuclear cells from healthy donors. PA was capable to induce apoptosis in cells from CML patients exhibiting functional MDR phenotype but not in P-glycoprotein expression. In addition, PA was effective in chronic as well as in blast phase of CML. Moreover, similar apoptotic index induced by PA was observed in low, intermediate and high-risk Sokal score as well as in samples from the group of patients with clinical resistance to interferon and/or imatinib and non-treated patients. These results suggest that PA may be an effective agent for the treatment of CML.     

Toxic-dose warfarin-induced apoptosis and its enhancement by gamma ionizing radiation in leukemia K562 and HL-60 cells is not mediated by induction of oxidative stress

The purpose of this study was to test the hypothesis that warfarin may enhance free radical production and oxidative damage on cancer cells. We examined the possible concentration-dependent effect of warfarin on cytotoxicity with respect to oxidative stress on leukemia cell lines (K562 and HL-60) and normal human peripheral blood mononuclear cells (PBMC). Gamma radiation was used as a positive control agent for oxidative stress. At all concentrations of warfarin (5–200 μM), 5-amino-2,3-dihydro-1,4-phthalazinedione (luminol)- and bis-N-methylacridinium nitrate (lucigenin)-amplified chemiluminescence responses and lipid peroxidation and protein oxidation were stable after 72 h incubation at 37°C. However, The 2′,7′-dichlorofluorescein diacetate (DCFH-DA) oxidation was increased when cells were incubated with high concentrations (50–200 μM) of warfarin. In these concentration ranges, warfarin reduced cell growth in a dose-dependent manner, producing apoptosis. Our results also revealed that at concentrations above 5 μM, warfarin had a potentiating effect on radiation-mediated growth inhibition and apoptosis. Furthermore, marked effects were observed on leukemic cells compared with PBMC. We report here that the increase of DCFH oxidation might be due to the increase in the release of cytochrome C caused by warfarin, as cytosolic cytochrome C content was significantly elevated in the warfarin-treated cells compared with control cells, and because cotreatment with antioxidants N- acetylcysteine or 4,5-dihydroxy-1,3-benzene-disulfonic acid (Tiron) was unable to prevent cytochrome C release and DCFH oxidation induced by the drug. Taken together, these results suggest that high warfarin concentrations may be toxic to leukemic cells in vitro through apoptosis, although at the pharmacological concentrations (<50 μM), warfarin has no prooxidant or cytotoxic effect on PBMC, K562, and HL-60 cells. In addition, when the treatment of leukemic cells with warfarin at concentrations above 5 μM is combined with radiation, we observed an increase in radiation-induced cytotoxicity. The mechanism by which warfarin potentiates this cytotoxicity is unclear, but it may not be directly due to toxic damage induced by warfarin-generated free radicals.     

Antibacterial, antioxidant and cytotoxic activities of extracts of Conyza canadensis (L.) Cronquist growing in Tunisia

Antibacterial antioxidant and cytotoxic activities of petroleum ether, ethyl acetate and methanol extracts of Conyza Canadensis (L.) Cronquist were investigated. Antibacterial activity was evaluated using the agar diffusion and microwell dilution assays against four strains of bacteria. Antioxidant activity was measured by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method and the cytotoxic activity was tested against Hep-2 cells (laryngeal carcinoma cell line) using methylene blue assays. Among tested extracts, the methanolic extract exhibited important antibacterial activity. It also showed good antioxidant activity with 50% inhibition concentration (IC₅₀) of 120 μg/ml. Cytotoxicity of extracts was time depend, increasing with exposure time and concentration. At 72 h of incubation, the ethyl acetate and petroleum ether extracts demonstrated effective cytotoxic activity against Hep-2 cells with IC₅₀ values of 45 and 50 μg/ml, respectively.     

Antitumor activity of arylacetylshikonin analogues

Twenty one phenylacetylshikonin analogues were synthesized from various substituted phenyl acetic acids and their cytotoxicity values against A549, K562 and L1210 cell lines and antitumor action in mice bearing S-180 cells were measured. All of phenylacetylshikonin analogues expressed a potent cytotoxicity (ED₅₀, 0.1–1.80 μg/ml) against L1210 and K562 cells. L 1210 cells were the most sensitive to shikonin analogues among these cells. Except 4-methoxyphenylacetylshikonin (0.098μg/ml) and α-acetoxyphenylacetylshikonin (0.10μg/ml), all other shikonin derivatives showed higher ED₅₀ values than phenylacetylshikonin (0.13μg/ml) in L 1210. In K562 cell, α-substitution of phenylacetylshikonin (0.1 μg/ml), while other substitutions increased it slightly; 4-methoxyphenylacetylshikonin (0.033 μg/ml) showed a exceptionally good cytotoxicity against K562 cell. 4-Halogenation tended to decrease the cytotoxic effect on L1210 cells, while it enhanced the effect on K562; 4-bromophenylacetyl [ED₅₀ (L1210)=1.76 μ/ml, ED₅₀ (K 562)=0.32 μg/ml] and 4-chlorophenylacetyl shikonin [ED₅₀ (L 1210)=1.64 μg/ml, ED₅₀ (K562)=0.32 μg/ml]. In contrast, A549 cells were much less sensitive to these shikonin analogues which showed ED₅₀ values of 1.5–13.5 μg/ml. Most of phenylacetylshikonin derivatives showed good antitumor activity in mice bearing S-180 cells. α-A-cetoxyphenylacetylshikonin and 4-dimethylaminophenylacetylshikonin showed highest T/C value (192–195%), implying that introduction of α-acetyl or of 4-dimethyl amino group gave a positive effect on the antitumor activity. Introduction of 4-dimethylamino group enhanced the antitumor activity as shown for 4-dimethylaminophenylacetylshikonin (T/C, 192%). It might be due to improvement of water solubility by dimethylamino group in the molecule.     

Effect of bacterial purified antigenic fractions on natural defence mechanisms

The in vitro ability of bacterial purified antigenic fractions to interfere with the immune system has been investigated on human mononuclear cells from peripheral blood. Exposure of purified monocytes to the drug at concentrations from 1 to 1000 micrograms/ml, for different periods from 0 to 18 h, significantly increased cell-mediated cytotoxicity against TU5 target cells. Moreover, monocytes exposed for 1 to 18 h to drug concentrations from 0.1 to 1000 micrograms/ml released significant amounts of tumor necrosis factor alpha in a dose-dependent manner in the culture supernatants. The drug was also tested on natural killer (NK) cell activity; mononuclear cells exposed to antigenic fractions for different periods showed a significant increase of NK cytotoxic activity against K562 target cells after 3 and 6, but not 0 and 18 h. Active concentrations were from 1 to 100 micrograms/ml, higher and lower doses being ineffective. Bacterial purified antigenic fractions thus have some ability to interfere in vitro with mechanisms of cytolysis mediated by cells and soluble factors.     

Polyoxygenated flavones; Synthesis,cytotoxicities and antitumor activity against ICR mice carrying S-180 cells

Fifty two flavones were synthesized from polyoxygenated dibenzoylmethanes which were obtained by a modified Baker-Venkataraman rearrangement, of 2-benzoyl oxyacetophenones. The following flavones among then showed good cytotoxic activities against L1210 and HL-60 cells; 2′-benzyloxy-5-methoxyflavone [ED₅₀(L1210)=4.9 μg/ml) ED₅₀(HL-60)=3.1 μg/ml] 2′-benzyloxy-5,7-dimethoxyflavone (8.2 μg/ml, 5.0 μg/ml), 2′-benzyloxy-5,7,8-trimethoxyflavone (5.9 μg/ml, 11.0 μg/ml), 2′-hydroxy-5,7-dimethoxyflavone (8.3 μg/ml 4.9 μg/ml) 2′-hydroxy-5-methoxyflavone (4.2 μg/ml, 2.7 μg/ml), 2′-hydroxy-5,7,8-trimethoxyflavone (9.8 μg/ml, 6.2 μg/ml), 2′-benzyloxy-5-hydroxyflavone (5.2 μg/ml, 3.6 μg/ml), and 5,2′-dihydroxyflavone (5.1 μg/ml, 4.0 μg/ml). Presence of 5-methoxy group potentiated the cytotoxic activity, while the existence of 7-methoxy group decreased the activity. 5-Hydroxy or methoxy, activates 4-carbonyl group, while 7-methoxy group deactivates the carbonyl group. From these observation it was concluded that the activation of carbonyl group at C-4 of a flavone is important for the enhancement of the cytotoxic activity. The presence of both 5-hydroxy and 2′-benzyloxy- or 2′-hydroxy group enhanced the antitumor activity; 2′-benzyloxy-5-hydroxy-7-methoxyflavone (T/C=144%), 5,2′-dihydroxy-7-methoxyflavone (T/C=132%), and 5,2′-dihydroxy-6,7,8,6′ tetramethoxyflavone (T/C=172%). 2′-Hexanoylation of 5,2′-dihydroxy-flavones did not improve the antitumor activity; 2′-hexanoyloxy-5-hydroxy-7-methoxyflavone showed T/C=132%, about the same as that of 5,2′-dihydroxy-7-methoxyflavone (T/C=130%)     

Brazilian marine sponge <Emphasis Type="Italic">Polymastia janeirensis</Emphasis> induces apoptotic cell death in human U138MG glioma cell line,but not in a normal cell culture

Summary  Marine sponges have been prominently featured in the area of cancer research. Here, we examined the anti-proliferative effects of crude extracts (aqueous and organic) of the Brazilian marine sponge Polymastia janeirensis in the U138MG human glioma cell line. Moreover, we examined the effects of extracts on selective cytotoxicity in the glioma cells in comparison with a normal cell culture. Exposure of glioma cells to treatments (24 h) resulted in cell number decrease at all doses tested, with both aqueous and organic extracts (IC₅₀ <20 and <30 μg/ml, respectively). Parallel to this result, sponge extracts reduced glioma cell viability (IC₅₀ <15 μg/ml for both extracts). However, higher doses (50 and 100 μg/ml) induced a stronger cytotoxic effect when compared to the lower dose tested (10 μg/ml), inhibiting more than 80% of cellular growth and viability. Propidium iodide uptake and flow cytometry analysis further showed that sponge extracts caused necrosis in the glioma cell line at higher doses, while a high percentage of apoptotic glioma cells were observed at 10 μg/ml. Moreover, apoptosis was prevented by the pan-caspase inhibitor Z-VAD, suggesting that marine sponge extracts, at lower doses, induce caspase-dependent apoptosis in U138MG glioma cells. Surprisingly the extracts herein tested were more effective than temozolomide, a potent inductor of apoptosis used for the treatment of malignant gliomas. Furthermore, our results suggested a selectivity cytotoxic effect on glioma cell line in comparison with a normal cell culture, since the effect on viability found in glioma cells was not observed in astrocyte cultures with the lower dose (10 μg/ml). Thus, this marine sponge may be considered a good candidate for development of new cancer medicines with antitumor activity against gliomas.     

The biological activity of G-quadruplex DNA binding papaverine-derived ligand in breast cancer cells

Summary  It was shown previously that the papaverine oxidation products 6a,12a-diazadibenzo-[a,g]fluorenylium derivative (ligand 1) and 2,3,9,10-tetramethoxy-12-oxo-12H-indolo[2,1-a]isoquinolinium chloride (ligand 2) bind to guanine-quadruplexes (G4) of single stranded G-rich 3′-overhangs of mammalian telomeric DNA. Here we show the biological activity of ligand 1. This compound exhibit antiproliferative activity in MCF-7 cells (IC₅₀ for ligand 1 = 14.16 ± 0.01 μM, 24 h, 1.158 ± 0.056 μM, 72 h. PCNA levels were not altered after treatment of MCF-7 cells with concentrations of ligand 1 which, however, led to alterations in the cell cycle. 5 and 10 μM of the ligand 1 arrested cells in the G0/G1 phase of the cell cycle and this led to a decrease of cells in the S phase. Intracellular accumulation of ligand 1 was observed even after a cell passage and medium exchange in fluorescence microscopy while low concentrations of ligand 1 (0.001 to 0.1 μM) inhibited telomerase activity as shown by TRAP assay.     

Antiplasmodial and antitrypanosomal activity of plants from the Kingdom of Saudi Arabia

The antiplasmodial and antitrypanosomal activity of the methanol extracts of 42 plants collected from the Kingdom of Saudi Arabia and some fractions obtained thereof were evaluated. The antiplasmodial activity was tested in vitro against chloroquine-resistant strain (K1) and sensitive strain (FCR3), and the antitrypanosomal activity was tested in vitro against Trypanosoma brucei brucei GUTat 3.1 strain. For host cells, the cytotoxicity of the active extracts was also evaluated against the MRC5 human cell line. Only extracts of three samples demonstrated good antiplasmodial activity (IC₅₀ < 12.5 and > 1.56 μg/ml, score 2), the methanol extracts of Lycium shawii, Heliotropium zeylanicum and the petroleum ether-soluble fraction of the methanol extract of Caralluma tuberculata, while extracts of the remaining 42 plants were inactive (IC₅₀ > 12.5 μg/ml, score 1). As for the antitrypanosomal activity, the methanol extract of Solanum schimperianum demonstrated the highest activity (IC₅₀ 0.061 μg/ml), followed by the petroleum ether-soluble fraction of the methanol extract of C. tuberculata (IC₅₀ 0.5 μg/ml). The chloroform-soluble fraction of the methanol extract of C. tuberculata was moderately active (IC₅₀ 3.5 μg/ml), with low cytotoxicity (IC₅₀ 62.6 μg/ml) and moderate selectivity index (SI 17.9). The methanolic extracts of 34 plants showed good activity with score 2 (IC₅₀ < 12.5 and > 1.56 μg/ml), while the extracts of seven plants were inactive (IC₅₀ > 12.5 μg/ml, score 1).     

Design, synthesis, and in vitro evaluation of cytotoxic activity of new substituted 1,4-benzoquinones and hydroquinones

A new series of p-benzoquinones, hydroquinones, and quinol dimethyl ethers substituted by a pyrazole ring either directly or after an oxoethyl linker was synthesized and screened for in vitro cytotoxic activity. Compounds 8d, f, g, i, and 9c, f, and 13c exhibited broad-spectrum activity (GI₅₀ MG-MID values 9.27–14.72 μM). With regard to sensitivity, compounds 8f and 9c, f have proved to possess a remarkable activity against leukemia tumor cell lines (GI₅₀ = 3.43–5.03 μM). Indeed, compound 13c showed the highest activity profile against individual leukemia subpanel cell line SR (GI₅₀ = 0.91 μM).     

Cisplatin-induced toxicity in immortalized renal cell lines established from transgenic mice harboring temperature sensitive SV40 large T-antigen gene

 We established renal cell lines from definite nephron segments which were microdissected from kidneys of transgenic C57BL/6 mice, harboring the large T-antigen gene of temperature-sensitive mutant simian virus 40, pSVtsA58(ori-). Cell culture was under a humidified atmosphere of 5% CO₂ in air, on collagen-coated dishes, and in RITC80-7 medium with 5% fetal bovine serum, 10 μg/ml transferrin, 1 μg/ml insulin, 10 ng/ml recombinant human EGF, penicillin and streptomycin. Cell line which kept contact inhibition character was established from each segment. Cells derived from distal tubule, cortical and outer medullary collecting duct possessed their cyclic AMP response to arginine-vasopressin, like their original nephron segment. On the other hand, cells derived from terminal proximal tubules (S3 segment) formed a cobblestone-like confluent monolayer, and did not respond to arginine-vasopressin like their fresh segments. Since cisplatin, a well-known nephrotoxic substance, damages proximal tubules (especially S3) rather than collecting ducts, we assayed cell number, protein content, and ATP content of cultured S3 cells at various times after addition of 0.2 mM cisplatin. Decrease of cell number, total protein content and total ATP content of culture cells occurred after 10 h incubation with 0.2 mM cisplatin. The 50% lethal dose (LD₅₀) of cisplatin in S3 cells was 4×10^{–  5} M after 20 h incubation and 8.5×10^{–  6} M after 40 h incubation. Outer medullary collecting duct (OMCD) cells were damaged 30% maximally after 20 h incubation with cisplatin, and LD₅₀ in them became 2.5×10^{–  5} M after 40 h incubation. We could show that the LD₅₀ of cisplatin in the OMCD cell line was three times higher than that in the S3 cell line. Thus, these cell lines are the first in the kidney to definite the segmental origin and to maintain some differentiated unique functions. They are valuable for studies on intrarenal site-specific actions and possible mechanisms of action of pharmacological and toxic substances. Received: 3 May 1995 / Accepted 4 September 1995     

Recognition of pharmacophore of ar-turmerone for its anticancer activity

For the analysis of structure activity relationship of ar-turmerone analogues, the compounds containing the various substituents on the phenyl ring and 1(or 2)-naphthyl group in the place of phenyl of ar-turmerone were prepared and tested their cytotoxicity against HL-60, K-562, and L1210 leukemia cellsin vitro. The substituents at para position are methoxy, phenoxy, methyl, trifluoromethyl, fluoro, and chloro. Atmeta position methoxy, methyl, trifluoromethyl, or chloro groups and atortho position methoxy or chloro group were introduced. Against HL-60 and K-562 cells, ED₅₀ values of the analogues are ranged from 0.8 to 30.0 μg/ml. Against L1210 cell, these are located more than 20.0 μg/ml. However, 5-carboethoxy-2-methyl-6-(1-naphthyl)-2-octen-4-one (5n) possesses ED50 valuses 0.8, 2.1, 6.5 μg/ml against HL-60, K-562, L1210 cells, respectively. The electronic nature of the subsituents on phenyl ring of ar-turmerone dose not affect the biological activity. Therefore the flat structure of aromatic portion of ar-turmerone analogues is the more important factor for their activity rather than its electronic nature. The potentiation of the cytotoxicity with the enlargement of aromatic ring region also supports the importance of the plane structure of this area. The restriction of the single bond rotation between C-6 and aromatic ring through the introduction of substituents at theortho position of phenyl ring and the increment of size of alkyl group at C-6 position enhances the activity. Therefore the effective conformation should be the one having the orthogonal arrangement between the aromatic ring and the side chain.     

Cytotoxic activities of new iron(III) and nickel(II) chelates of some <Emphasis Type="Italic">S</Emphasis>-methyl-thiosemicarbazones on K562 and ECV304 cells

The S-methyl-thiosemicarbazones of the 2-hydroxy-R-benzaldehyde (R= H, 3-OH 3-OCH₃ or 4-OCH₃) reacted with the corresponding aldehydes in the presence of FeCl₃ and NiCl₂. New ONNO chelates of iron(III) and nickel(II) with hydroxy- or methoxy-substitued N ¹,N ⁴-diarylidene-S-methyl-thiosemicarbazones were characterized by means of elemental analysis, conductivity and magnetic measurements, UV-Vis, IR and ¹H-NMR spectroscopies. Cytotoxic activities of the compounds were determined using K562 chronic myeloid leukemia and ECV304 human endothelial cell lines by MTT assay. It was determined that monochloro N ¹-4-methoxysalicylidene-N ⁴-4-methoxysalicylidene-S-methyl-thiosemicarbazidato-iron(III) complex showed selective anti-leukemic effects in K562 cells while has no effect in ECV304 cells in the 0.53 μg/ml (IC₅₀) concentrations. Also, some methoxy-substitued nickel(II) chelates exhibit high cytotoxic activitiy against both of these cell lines in low concentrations. Cytotoxicity data were evaluated depending on cell lines origin and position of the substituents on aromatic rings.     

外源性三磷酸腺苷和腺苷对肿瘤细胞增殖的影响

目的　研究三磷酸腺苷 (ATP)和腺苷 (ADO)对人红白血病细胞株K5 6 2、人胃中分化腺癌细胞株HGC 2 7、人食管低分化鳞癌细胞株TE 13细胞增殖的影响。方法　采用MTT法测定ATP和ADO抑制肿瘤细胞增殖的作用 ,Wright’s Giemsa染色观察细胞形态学的改变。结果　在 0 0 1～ 1 0mmol·L-1浓度范围内 ,ATP和ADO可不同程度地抑制TE 13、HGC 2 7和K5 6 2细胞的增殖 ,其中对TE 13的作用最强 ;ATP和ADO作用 72h后 ,对TE 13细胞的抑制率分别为80 5 2 %和 74 0 3%。细胞经高浓度 (1mmol·L-1)的ATP和ADO处理后 ,细胞形态出现了凋亡的特征。结论　ATP抗TE 13和HGC 2 7肿瘤细胞增殖的作用与其代谢产物ADO部分相关 ,ATP和ADO的作用机制可能涉及细胞凋亡     

As2S2诱导K562细胞凋亡及其机制

目的:探索As_2S_2对K562细胞的作用及其机制.方法:As_2S_2对K562细胞的生长抑制作用用细胞计数法;细胞凋亡的检测用流式细胞分析、基因组DNA电泳、细胞形态学观察等方法;Western-blot方法用于蛋白表达的检测;基因表达的变化用半定量RT-PCR方法.结果:As_2S_2浓度在1-5μmol/L作用24-72 h即可抑制K562细胞生长,大于3μmol/L时可诱导K562细胞凋亡.As_2S_2能降低K562细胞中Bcr-Abl蛋白水平及 c-abl和 Bcr-Abl PTK活性,但不调变bcr-abl基因表达水平.As_2S_2也能诱导慢性粒细胞性白血病(CML)患者单个核细胞凋亡,且Ph~ 单个核细胞比Ph~- 单个核细胞对As_2S_2诱导的凋亡更敏感.结论:As_2S_2可通过降低Bcr-Abl蛋白含量而诱导CML细胞凋亡.As_2S_2可能为治疗CML的有效药物.     

Antitumor activities of new platinum compounds,DWA2114R,NK121 and 254-S,against human leukemia cells sensitive or resistant to cisplatin

Summary (R)-(-)-1,1-(2-amino-methylpyrrorodine)-platinum(II) (DWA2114R), cis-1,1-cyclobutanedicarboxylato(2R)-2-methyl-1,4-butanediammineplatinum(II) (NK121; CI-973) and glycolate-o,-o-diammine platinum(II) (254-S; NSC375101D) are new platinum compounds developed in Japan. We studied the antitumor effects of these compounds on the cisplatin (cis-diamminedichloroplatinum, DDP)-resistant human leukemia cell line, K562/DDP. K562/DDP cells were 10-fold resistant to DDP, while the cells showed minimal cross-resistance to carboplatin (2.1-fold) and DWA2114R (3.3-fold), and were as sensitive to NK121 (1.6-fold) and 254-S (1.0-fold) as the parent cells. Increases in exposure time of K562 cells to DWA2114R resulted in progressive shifting of the dose-response curve to the left, or more effective cell growth inhibition of the cells. Time dependency indices (ID₈₀ obtained from dose-response curve after 1 hr-exposure of K562 cells to drug followed by 72 hr-culture without drug/ID₈₀ after 24 hr-exposure) of DDP, NK121 and 254-S were 10, 8 and 20, respectively. A multidrug resistant cell-line, MOLT-3/TMQ₂₀₀, was as sensitive to platinum compounds as the parent MOLT-3 cells. Little or no influence of tumor cell density was observed in the growth inhibition of MOLT-3 or K562 cells induced by these new compounds even if cells were concentrated to a density of 10⁸ cells/ml. These results indicate that NK121 and 254-S may overcome the drug resistance developed in the patients after treatment with DDP. The antitumor effect of DWA2114R is more dependent not only on drug-concentration but also on exposure time than that of DDP, suggesting that continuous infusion rather than bolus administration appears the favorable schedule in clinical trials. Address for offprints: Y. Takemura, Department of Laboratory Medicine, National Defense Medical College, 3-2 Namiki, Tokorozawa, Saitama 359, Japan     

Chemical composition and cytotoxic activity of the leaf essential oil of <Emphasis Type="Italic">Eugenia zuchowskiae</Emphasis> from Monteverde,Costa Rica

The leaf essential oil of Eugenia zuchowskiae from Monteverde, Costa Rica, has been obtained by hydrodistillation and analyzed by GC–MS. The principal constituents of E. zuchowskiae leaf oil were α-pinene (28.3%), β-caryophyllene (13.2%), α-humulene (13.1%), and α-copaene (8.1%). The leaf essential oil of E. zuchowskiae showed pronounced in-vitro cytotoxic activity against MCF-7, MDA-MB-468, and UACC-257 human tumor cell lines. The major components showed cytotoxic activities comparable to doxorubicin (LC₅₀ 14–70 μg/ml).