A crystalline compound (BM-ANF1) from the Indian toad (Bufo melanostictus, Schneider) skin extract, induced antiproliferation and apoptosis in leukemic and hepatoma cell line involving cell cycle proteins.

In our earlier communication, it was reported that Indian toad (Bufo melanostictus) skin extract (TSE) possesses antiproliferative and apoptogenic activity in U937 and K562 cells [Giri et al., 2006. Antiproliferative, cytotoxic and apoptogenic activity of Indian toad (Bufo melanostictus, Schneider) skin extract in U937 and K562 cells. Toxicon 48 (4), 388-400]. In the present study, a compound (BM-ANF1) has been isolated from the TSE by alumina gel column chromatography, crystallized and evaluated for its antiproliferative and apoptogenic activity in U937, K562 and HepG2 cells. BM-ANF1 produced dose-dependent inhibition of U937, K562 and HepG2 cell growth. The antiproliferative activity was reflected by the MTT assay and demonstrated by the reduced expression of proliferative cell nuclear antigen (PCNA). Flow-cytometric analysis showed that BM-ANF1 arrested the cell cycle at G1 phase and enhanced annexin-V binding in U937 and K562 cells. Scanning electron microscopic and fluorescent microscopic analysis of U937 and K562 cells revealed the apoptogenic nature of the compound. Alkaline comet assay showed that BM-ANF1 produced DNA fragmentation. The dose-dependent expression of caspase 3 indicated that the apoptogenic properties of BM-ANF1 were mediated through the activation of downstream effector nucleases in the cancer cells. The increased expression of p53 and moderate expression of p21(Cip1)/p27(Kip1) due to BM-ANF1 treatment in HepG2 cells supported that the apoptogenic activity of BM-ANF1 was mediated through p53 tumor-suppressor gene expression followed by the expression of p21(Cip1) and p27(Kip1) and it was likely to be linked with cell cycle arrest at G1 phase in cancer cells. From the present study, it may be suggested that the crystalline compound, BM-ANF1, was antiproliferative and apoptogenic in human leukemic and hepatoma cells.     

Cytotoxic and apoptogenic effect of Swietenia mahagoni (L.) Jacq. leaf extract in human leukemic cell lines U937, K562 and HL-60

The apoptogenic activity of Swietenia mahagoni leaf extract (SMLE) was investigated against three human leukemic cell lines – U937, K562 and HL-60. SMLE inhibited cell growth and metabolic activity of the leukemic cells and showed characteristic features of apoptosis. Flow-cytometric analysis showed that SMLE arrested U937 and K562 cell populations in the G2-M phase and the HL-60 cell population in the G1 phase of cell cycle. SMLE induced apoptosis was found to be mediated through mitochondrial intrinsic pathway involving the release of cytochrome c into the cytosol and activation of caspase-9 and caspase-3. Two flavonoids, catechin and quercetin-3-O-glucoside, isolated from SMLE, were found to inhibit the growth and metabolic activity of U937, K562 and HL-60 cells at much lower concentrations thus indicating that these two flavonoids might be the active ingredients responsible for the anti-leukemic activity of SMLE.     

A heat stable protein toxin (drCT-I) from the Indian Viper (Daboia russelli russelli) venom having antiproliferative, cytotoxic and apoptotic activities.

A heat stable 7.2kDa protein toxin (drCT-I) has been purified and crystallized from Indian Daboia russelli russelli venom (Roy Choudhury et al., 2006. Acta Cryst. F Struct Biol Cryst Commun, 62(Pt. 3), 292). The N-terminal (first 20) amino acid sequence of drCT-I was LKCNKLVPLFYKTCPAGKNL, which showed sequence homology to cytotoxins isolated from Naja venom. drCT-I has been evaluated for anticancer activity against EAC cells in vivo and human leukemic cells (U937, K562) in vitro. drCT-I (125 microg/kg, i.p/day for 10 days) significantly decreased EAC cell count, cell viability (p<0.001) and significantly increased the survival time of tumour bearing mice (T/C% 178.64, p<0.01) in comparison to untreated tumour bearing control. drCT-I, produced dose and time-dependent inhibition of U937 and K562 cell growth and had an IC50 of 8.9 and 6.7 microg/ml respectively after 24h treatment. The reduced MTT values after drCT-I treatment indicated its cytotoxic nature, which supported its antiproliferative action. Scanning electron microscopy and confocal microscopy in U937 and K562 cells after drCT-I treatment indicated certain features of apoptosis such as membrane blebbing, perforations, nuclear fragmentation. The induction of apoptosis was further confirmed by phosphatidylserine externalization observed using annexinV-FITC/PI staining and flow cytometric analysis. drCT-I brought about apoptosis by G1 phase arrest of the cell cycle. The effect of drCT-I on normal human peripheral blood mononuclear cell (PBMNC) viability and cytotoxicity was studied in culture and was found to be lower than that on U937 and K562 cells. Thus both in vivo and in vitro experimental results suggested that drCT-I possessed anticancer potential.     

Anticancer activity of a low immunogenic protein toxin (BMP1) from Indian toad (Bufo melanostictus, Schneider) skin extract

Earlier, a protein (BMP1, MW-79kDa) had been isolated from Indian toad (Bufo melanostictus) skin aqueous extract possessed anticancer activity against EAC bearing mice (Bhattacharjee et al., 2011). In the present study, the anti-proliferative and apoptogenic activities of BMP1 have been evaluated in leukemic (U937 and K562) and hepatoma (HepG2) cells. BMP1 dose dependently inhibited U937 and K562 cell growth having IC₅₀ values of 49 μg/ml and 30 μg/ml respectively. The anti-proliferative activity of BMP1 was observed in MTT assay, proliferating cell nuclear antigen (PCNA) expression and cell cycle arrest study. Flow-cytometric data revealed that BMP1 arrested cell cycle in U937 and K562 cells at Sub-G1 and G1 phases. The BMP1-induced dose dependent expressions of CDKIs (p21^cip1 and p27^kip1) and inhibition of CDK2 and PCNA expression in HepG2 cells support the inhibition of cell proliferation due to G1 arrest. BMP1-induced apoptosis analyzed by annexin-V binding study and the DNA fragmentation by comet assay were correlated with the sub-G1 arrest. The parallel induction of bax and p53 expression in HepG2 cells and the up-regulation of caspase 3 and caspase 9 due to BMP1 treatment indicated the involvement of p53-dependent intrinsic pathway of apoptosis. BMP1 was found to be low immunogenic in nature.     

Cytotoxic effects of Coptis chinensis and Epimedium sagittatum extracts and their major constituents (berberine, coptisine and icariin) on hepatoma and leukaemia cell growth

1. The present study was conducted to evaluate the cytotoxic effects of Coptis chinensis and Epimedium sagittatum extracts and their major constituents on hepatoma and leukaemia cells in vitro. 2. Four human liver cancer cell lines, namely HepG2, Hep3B, SK-Hep1 and PLC/PRF/5, and four leukaemia cell lines, namely K562, U937, P3H1 and Raji, were used in the present study. 3. Of the two crude drugs, C. chinensis exhibited the strongest activity against SK-Hep1 (IC50 = 7 microg/mL) and Raji (IC50 = 4 microg/mL) cell lines. The IC50 values for C. chinensis on HepG2, Hep3B and PLC/PRF/5 cell lines were 20, 55 and 35 microg/mL, respectively. The IC50 values for C. chinensis on K562, U937 and P3H1 cell lines were 29, 29 and 31 microg/mL, respectively. 4. With the exception of HepG2 and Hep3B, the E. sagittatum extract inhibited the proliferation of all cell lines (SK-Hep1, PLC/PRF/5, K562, U937, P3H1 and Raji), with IC50 values of 15, 57, 74, 221, 40 and 80 microg/mL, respectively. 5. Interestingly, the two major compounds of C. chinensis, berberine and coptisine, showed a strong inhibition on the proliferation of both hepatoma and leukaemia cell lines, with IC50 values varying from 1.4 to 15.2 microg/mL and from 0.6 to 14.1 microg/mL, respectively. However, icariin (the major compound of E. sagittatum) showed no inhibition of either the hepatoma or leukaemia cell lines. 6. The results of the present study suggest that the C. chinensis extract and its major constituents berberine and coptisine possess active antihepatoma and antileukaemia activities.     

Induction of cell death and modulation of Annexin A1 by phytoestrogens in human leukemic cell lines

BackgroundPhytoestrogens are polyphenolic plant compounds which are structurally similar to the endogenous mammalian estrogen, 17β-estradiol. Annexin A1 (ANXA1) is an endogenous protein which inhibits cyclo-oxygenase 2 (COX-2) and phospholipase A2, signal transduction, DNA replication, cell transformation, and mediation of apoptosis.ObjectiveThis study aimed to determine the effects of selected phytoestrogens on annexin A1 (ANXA1) expression, mode of cell death and cell cycle arrest in different human leukemic cell lines.MethodsCells viability were examined by MTT assay and ANXA1 quantification via Enzyme-linked Immunosorbent Assay. Cell cycle and apoptosis were examined by flow cytometer and phagocytosis effect was evaluated using haematoxylin-eosin staining.ResultsCoumestrol significantly (p < 0.05) reduced the total level of ANXA1 in both K562 and U937 cells and genistein significantly (p < 0.05) reduced it in K562, Jurkat and U937 cells, meanwhile estradiol and daidzein induced similar reduction in U937 and Jurkat cells. Coumestrol and daidzein induced apoptosis in K562 and Jurkat cells, while genistein and estradiol induced apoptosis in all tested cells. Coumestrol and estradiol induced cell cycle arrest at G2/M phase in K562 and Jurkat cells with an addition of U937 cells for estradiol. Genistein induced cell cycle arrest at S phase for both K562 and Jurkat cells. However, daidzein induced cell cycle arrest at G0/G1 phase in K562, and G2/M phase of Jurkat cells. Coumestrol, genistein and estradiol induced phagocytosis in all tested cells but daidzein induced significant (p < 0.05) phagocytosis in K562 and Jurkat cells only.ConclusionThe selected phytoestrogens induced cell cycle arrest, apoptosis and phagocytosis and at the same time they reduced ANXA1 level in the tested cells. The IC50 value of phytoestrogens was undetectable at the concentrations tested, their ability to induce leukemic cells death may be related with their ability to reduce the levels of ANXA1. These findings can be used as a new approach in cancer treatment particularly in leukemia.     

Hyperforin a constituent of St John's wort (Hypericum perforatum L.) extract induces apoptosis by triggering activation of caspases and with hypericin synergistically exerts cytotoxicity towards human malignant cell lines.

Hyperforin (HP) is an abundant component of St John's wort with antibiotic and antidepressive activity. We report here the ability of HP and that of polyphenolic procyanidin B2 (PB-2) to inhibit the growth of leukemia K562 and U937 cells, brain glioblastoma cells LN229 and normal human astrocytes. HP inhibited the growth of cells in vitro with GI(50) values between 14.9 and 19.9 microM. The growth inhibitory effect of PB-2 was more pronounced in leukemia cell lines K562 and U937, the GI(50) concentrations being about 12.5 microM established after 48 h incubation differed significantly (P<0.05) from those of LN229 and normal human astrocytes (103.1 and 96.7 microM), respectively. Further, HP and hypericin (HY) (a naphthodianthrone from St John's wort) acted synergistically in their inhibitory effect on leukemic (K562, U937) cell growth. Cell death occurred after 24 h treatment with HP and PB-2 by apoptosis. A dose-dependent loss of membrane phospholipid asymmetry associated with apoptosis was induced in all cell lines as evidenced by the externalization of phosphatidylserine (PS) and morphological changes in cell size and granulosity by scatter characteristics. In leukemia U937 cells, HP increased the activity of caspase-9 and caspase-3 and in K562 cells caspase-8 and caspase-3. In addition, the broad spectrum caspase inhibitor z-VAD-fmk inhibited both the appearance of PS exposure and the activation of caspases, illustrating the functional relevance of caspase activation during HP-induced apoptosis. Cytocidal effects of HP and its cooperation with HY on tumor growth inhibition in a synergistic manner make the St John's wort an interesting option in cancer warranting further in vitro and in vivo investigation.     

Anti-leukemic activity of sulfonoquinovosyldiacylglyceride (SQDG): a constituent of Azadirachta indica leaves

The sulfonoquinovosyldiacylglyceride (SQDG) isolated from the leaves of Azadirachta indica showed significant anti-leukemic activity in human leukemic cell lines U937 and K562 with IC₅₀ of 9 μg/ml. SQDG treated leukemic cells showed chromatin condensation, apoptotic body formation, and increased caspase 3 production indicating apoptosis. Cell cycle study revealed that the treated leukemic cells accumulated in the sub-G₁ phase; the cell cycle was halted in this phase and the DNA content decreased in other phases.     

Apoptosis inducing activity of viscin, a lipophilic extract from Viscum album L

Detection of antiproliferative activity and bioactivity-guided fractionation of viscin, a lipophilic extract from Viscum album L., led to the isolation of betulinic acid, oleanolic acid and ursolic acid as active components. Viscin, betulinic acid, oleanolic acid and ursolic acid inhibited growth and induced apoptotic cell death in Molt4, K562 and U937 leukaemia cells. The growth inhibitory effect of viscin was more pronounced in Molt4 and U937 cells (IC50 (concentration that inhibited cell proliferation by 50%): 118 +/- 24 and 138 +/- 24 microg mL(-1)) than in K562 cells (IC50: 252 +/- 37 microg mL(-1)). Oleanolic acid was the least effective in all cell lines (7.5-45.5% inhibition at 10 microg mL(-1)) and ursolic acid the most active in Molt4 and U937 cells (81.8 and 97.8% inhibition, respectively, at 5 microg mL(-1)). A dose-dependent loss of membrane phospholipid asymmetry associated with apoptosis was induced in all cell lines as shown in flow cytometry by the externalization of phosphatidylserine and morphological changes in cell size and granularity. There were differences in individual cell lines' response towards the apoptosis-inducing effect of viscin, betulinic acid, oleanolic acid and ursolic acid. The triterpenoids beta-amyrin, beta-amyrinacetate, lupeol, lupeolacetate, beta-sitosterol and stigmasterol, and the fatty acids oleic acid, linoleic acid, palmitic acid and stearic acid were also present in the lipophilic extract.     

苦参碱对U937细胞及人脐静脉血管内皮细胞增殖的影响

目的：观察苦参碱（Matrine，Mat）对U937细胞及人脐静脉血管内皮细胞（HUVECs）增殖的影响。方法：采用体外培养技术，通过细胞形态、MTT实验、细胞周期测定观察Mat对U937细胞及HUVECs增殖的影响。结果：Mat（0．2～0．5mg／mL）作用24h后对U937细胞均有增殖抑制作用（P〈0．05或P〈0．01），在该浓度范围内呈剂量和时间依赖性，其作用U937细胞48h的半数抑制浓度（IC50）约为0．4mg／mL，有效作用时间为1d；Mat（0．1～0．5mg／mL）作用24、48、72h后对HUVECs增殖无明显抑制作用，亦无剂量和时间依赖性（P〉0．05）；Mat（0．2～0．5mg／mL）作用U937细胞48h后，S期细胞比例增加，细胞发生S期阻滞（P〈0．05或P〈0．01）；Mat（0．1～0．5mg／mL）作用HUVECs 48h后，对细胞周期无明显影响（P〉0．05）。结论：一定浓度Mat对U937细胞具有增殖抑制作用，呈时间-剂量依赖关系。Mat在一定浓度和时间下不能抑制HUVECs增殖，对其细胞周期亦无明显影响。     

A lethal cardiotoxic-cytotoxic protein from the Indian monocellate cobra (Naja kaouthia) venom

A lethal cardiotoxic-cytotoxic protein (mol. wt. 6.76 kDa) has been purified from the Indian monocellate cobra (Naja kaouthia) venom by ion-exchange chromatography and HPLC. CD spectra indicated the presence of 23% α helix, 19% β sheets and 35% coil. Complete amino acid sequence was determined by MALDI, which showed similar homology with cardiotoxins/cytotoxins isolated from venom of other Naja species. Intraperitoneal LD₅₀ was 2.5 mg kg⁻¹ in BalbC male mice. In vitro cardiotoxicity studies on isolated guinea pig auricle showed that the molecule produced auricular blockade that was abolished after trypsin treatment. Cytotoxicity studies on human leukemic U937 and K562 cells showed that it significantly inhibited cell proliferation in a dose and time dependent manner, as observed by trypan blue exclusion method and tetrazolium bromide reduction assay. IC₅₀ on U937 and K562 cells were 3.5 μg/ml and 1.1 μg/ml respectively. Morphometry and cell sorting studies indicated apoptosis induction in toxin treated leukemic cells. Apoptosis was caspase 3 and 9 dependent and the treated leukemic cells were arrested in sub-G1 stage. There was an increase in Bax-Bcl2 ratio, decrease in HSP (Heat shock protein) 70 and HSP90 and induction of PARP cleavage after NK-CT1 treatment. The toxin showed low cytotoxic effect on normal human leukocytes as compared with imatinib mesylate. Further detailed cytotoxic and cardiotoxic effects at the molecular level are in progress.     

β-羟基异戊酰基紫草素对高表达酪氨酸激酶肿瘤细胞系的生长抑制作用(英文)

目的验证 β 羟基异戊酰基紫草素对体外培养的肿瘤细胞的生长抑制作用。 方法XTT比色法。结果低浓度的 β 羟基异戊酰基紫草素抑制人类白血病细胞K5 6 2和U937的生长 ,半数抑制浓度分别是 0 12 μmol/L和 0 14 μmol/L。在较高剂量下 ,β 羟基异戊酰基紫草素抑制酪氨酸激酶高表达细胞系大鼠SR 3Y1和KDR/Flk 1 NIH3T3细胞以及人类表皮细胞癌细胞A4 31的生长。其半数抑制浓度分别是 1 2 μmol/L、2 5 μmol/L、11 0 μmol/L。结论 β 羟基异戊酰基紫草素对多种肿瘤细胞的生长均有抑制作用     

Comparative cytotoxicity of 2,3,9-trimethoxypterocarpan in leukemia cell lines (HL-60, Jurkat,Molt-4, and K562) and human peripheral blood mononuclear cells

The purpose of this study was to investigate the antiproliferative activity of 2,3,9-trimethoxypterocarpan, a known pterocarpan with cytotoxic activity against many tumor cell lines, in a panel of four leukemia cell lines (HL-60, Molt-4, Jurkat, and K562) and on human peripheral blood mononuclear cells (PBMC). The pterocarpan showed IC₅₀ ranging from 0.1 to 0.5 μg/ml at leukemic cells after 72 h of incubation, with K562 being the most resistant cell line. This compound seemed to be selective to tumor cell lines, since at a concentration of 10 μg/ml after 72 h, it only reduced 19% of viable peripheral mononuclear cells.     

热疗加阿霉素对慢性白血病K562细胞株的抑制作用

目的观察热疗联合阿霉素对慢性髓系白血病细胞株K562的体外增殖抑制作用及凋亡的影响。方法采用MTT法确定阿霉素的工作浓度,以该浓度进行化疗或与热疗的联合,选择温度40℃及42℃,体外作用于K562。作用前及48h,采用台盼蓝拒染法检测肿瘤细胞的存活率;MTT法检测对肿瘤细胞增殖的抑制作用;流式细胞仪检测细胞凋亡。观察热疗联合阿霉素的抗肿瘤效果。结果作用48h后IC50为5μg/ml,以此为实验的工作浓度。单纯热疗60min对K562细胞有抑制作用(P<0.01),并随温度增高而增强;单纯化疗对K562细胞也有抑制作用;各热化疗组对K562均有明显的抑制作用(P<0.01),随着温度的增高而增强。流式细胞仪检测细胞凋亡,热疗组、化疗组及热化疗组的细胞凋亡率均较对照组显著升高,各组之间有显著性差异(P<0.01)。结论热疗联合阿霉素能增强对K562细胞的体外抑制作用,可以提高肿瘤细胞的凋亡率。     

眼镜蛇毒细胞毒素的分离、纯化及其抗癌活性

目的：研究眼镜蛇毒细胞毒素的抗癌活性。方法：应用Ｓｅｐｈａｄｅｘ　 Ｇ１００和 ＣＭ－Ｓｅｐｈａｒｏｓｅ ＦＦ柱层析,从眼镜蛇毒中分离、纯化细胞毒素组分,用ＭＴＴ法测定该组分对体外培养的人癌细胞的细胞毒性作用。结果：眼镜蛇毒细胞毒素对人癌细胞ＳＧＣ－７９０１、Ｂｅｌ－７４０２、Ｋ５６２和Ｕ９３７的抑制作用呈良好的量效关系,半数抑制浓度分别为 ４．１０、 ２． ０８、 ０． ２９和 ０．１７ μｇ／ｍｌ。结论：眼镜蛇毒细胞毒素对体外培养的人癌细胞有很强的杀伤作用。     

染料木黄酮对人白血病K562细胞凋亡及增殖的影响

目的:观察染料木黄酮(GEN)对人白血病细胞增殖及凋亡的影响,探讨其抗白血病的可能性。方法:不同浓度(10、20、30、40、50 mg/L),不同时间(6、12、24、48、72 h)染料木黄酮作用后,甲基噻唑基四唑(MTT)法检测K562细胞(慢性髓细胞性白血病细胞株)及人外周血单个核细胞增殖;DNA断裂梯带电泳、Annexin-V/PI双染色流式细胞仪分析检测GEN诱导K562细胞凋亡的作用。结果:GEN可有效地抑制肿瘤细胞增殖,而对正常细胞毒性较小(PBM-CIC50=35.5 mg/L和K562 IC50=13.2 mg/L),抑制作用呈明显的时间、剂量—效应关系(P<0.05);GEN体外能够诱导K562细胞凋亡,诱导作用呈时间、剂量依赖关系(P<0.05);结论:GEN具有抗白血病细胞的作用。     

Early changes in metabolism of leukemic cell lines upon induction of apoptosis by cytotoxic drugs

We evaluated real-time changes in extracellular acidification rates of human U937 and K562 leukemic cells treated with camptothecin or taxol. U937 cells treated with camptothecin or taxol for 30-60 min showed a continuous, irreversible decrease in extracellular acidification rate that was sensitive to amiloride. In contrast, U937 cells exposed to sodium azide showed an immediate, steep decrease in extracellular acidification rate that was reversible upon azide withdrawal. K562 cells required a >20-fold higher dose of camptothecin to promote similar changes in the extracellular acidification rate, with a corresponding resistance in their susceptibility to camptothecin- or taxol-induced apoptosis. The data show that irreversible commitment to apoptosis is associated with rapid metabolic changes that are reflected by decreased extracellular acidification rate and regulated by the Na(+)/H(+) antiporter. Moreover, detection of extracellular acidification rate changes was not restricted to a particular cell type or apoptosis pathway, making this a potentially useful tool to screen compounds for pro-apoptotic activity.     

A biflavonoid from Luxemburgia nobilis as inhibitor of DNA topoisomerases

The biflavonoid 2',3'-diidroochnaflavone ( 1), isolated from the leaves of Luxemburgia nobilis, was cytotoxic to murine Ehrlich carcinoma (IC50 = 17.2 microM) and human leukemia K562 cells (IC50 = 89.0 microM) in a concentration-dependent manner in 45 h cell culture. The acetyl (1a) and methyl (1b) derivatives of 1 were not cytotoxic to these tumour cells at 67.0 and 82.0 microM concentrations, respectively. Biflavonoid 1 as well 1a inhibit the activity of human DNA topoisomerases I and II-alpha as observed in relaxation and decatenation assays. In addition, we show that 1 is a DNA interacting agent, which causes DNA unwinding in an assay with topoisomerase I. Also, spectrophotometric titration of 1 with DNA resulted in a pronounced hypochromic effect.     

Cytotoxic and antioxidant activity of Achillea alexandri-regis

The cytotoxicity and antioxidant properties of herb extracts of Achillea alexandri-regis were studied. Combined chloroform and ethylacetate extracts exhibited a pronounced cytotoxic effect against HeLa cancer cells (IC50 = 25.92 +/- 4.96 microg/ml), and lower cytotoxicity against K562 leukemia cells (IC50 = 48.59 +/- 18.31 microg/ml). The methanol extract was found to be a moderately cytotoxic in vitro agent against HeLa and K562 cells. No suppressive activity was detected on non-malignant peripheral blood mononuclear cells (PBMC). The antioxidant activity of the methanol extract was assessed by DPPH radical scavenging. The methanol extract of A. alexandri-regis showed concentration dependent DPPH radical scavenging activity with IC50 = 36.14 +/- 0.05 microg/ml.