Viability Of HL-60 Cells Research Articles

The NO-modified HIV protease inhibitor as a valuable drug for hematological malignancies: Role of p70S6K

Covalent attachment of NO to the first approved HIV protease inhibitor Saquinavir (Saq-NO) expands the therapeutic potential of the original drug. Apart from retained antiviral activity, the modified drug exerts strong antitumor effects and lower toxicity. In the present study, we have evaluated the sensitivity of different hematological malignancies to Saq-NO. Saq-NO efficiently diminished the viability of Jurkat, Raji, HL-60 and K562 cells. While Jurkat and Raji cells (established from pediatric patients) displayed abrogated proliferative potential, HL-60 and K652 cells (originated from adults) exposed to Saq-NO treatment underwent caspase dependent apoptosis. In addition, similar sensitivity to Saq-NO was observed in mononuclear blood cells obtained from pediatric patients with acute lymphoblastic leukemia (ALL) and adult patients with acute myeloid leukemia (AML). Western blot analysis indicated p70S6 kinase as a possible intracellular target of Saq-NO action. Moreover, the addition of a NO moiety to Lopinavir resulted in improved antitumor potential as compared to the parental compound, suggesting that NO-derived HIV protease inhibitors are a potential new source of anticancer drugs with unique mode of action.

The pleiotropic effects of fisetin and hesperetin on human acute promyelocytic leukemia cells are mediated through apoptosis, cell cycle arrest, and alterations in signaling networks

Fisetin and hesperetin, flavonoids from various plants, have several pharmaceutical activities including antioxidative, anti-inflammatory, and anticancer effects. However, studies elucidating the role and the mechanism(s) of action of fisetin and hesperetin in acute promyelocytic leukemia are absent. In this study, we investigated the mechanism of the antiproliferative and apoptotic actions exerted by fisetin and hesperetin on human HL60 acute promyelocytic leukemia cells. The viability of HL60 cells was evaluated using the MTT assay, apoptosis by annexin V/propidium iodide (PI) staining and cell cycle distribution using flow cytometry, and changes in caspase-3 enzyme activity and mitochondrial transmembrane potential. Moreover, we performed whole-genome microarray gene expression analysis to reveal genes affected by fisetin and hesperetin that can be important for developing of future targeted therapy. Based on data obtained from microarray analysis, we also described biological networks modulated after fisetin and hesperetin treatment by KEGG and IPA analysis. Fisetin and hesperetin treatment showed a concentration- and time-dependent inhibition of proliferation and induced G2/M arrest for both agents and G0/G1 arrest for hesperetin at only the highest concentrations. There was a disruption of mitochondrial membrane potential together with increased caspase-3 activity. Furthermore, fisetin- and hesperetin-triggered apoptosis was confirmed by annexin V/PI analysis. The microarray gene profiling analysis revealed some important biological pathways including mitogen-activated protein kinases (MAPK) and inhibitor of DNA binding (ID) signaling pathways altered by fisetin and hesperetin treatment as well as gave a list of genes modulated ≥2-fold involved in cell proliferation, cell division, and apoptosis. Altogether, data suggested that fisetin and hesperetin have anticancer properties and deserve further investigation.

A novel in vitro assay for assessing efficacy and toxicity of antifungals using human leukaemic cells infected with Candida albicans

This study describes a novel in vitro assay that simultaneously determines antifungal efficiency and host cell toxicity using suspensions of human leukaemic cells (HL-60) infected with Candida albicans. The effect of Candida infection on host cell viability was evaluated by the microscopy of trypan blue-stained cells and lactate dehydrogenase (LDH) activity. The in vitro 'drug potency assay' utilized the Cell Counting Kit-8 and measured post-antifungal treatment viability of Candida-infected HL-60 cells and the ability of the antifungal treatment to prevent infection. LDH activity showed that 42% ± 4·0 and 85·3% ± 7·40 of HL-60 cells were killed following Candida infection at the multiplicity of infection (MOI) of 1 : 1 and 1 : 5, respectively. The antifungal nystatin (0·78-25 μmol l(-1) ) was found to inhibit C. albicans infection as seen by the significantly increased viability of HL-60 cells. Cytotoxicity of nystatin towards infected HL-60 cells was evident at higher concentrations and this was also confirmed by propidium iodide staining. An assay using undisturbed cell suspension conditions was successfully developed for assessing the selectivity of the antifungal therapy in the host-Candida environment. The assay employing Candida infection of host cell suspensions represents a promising method for testing interactions of antifungal compounds with both fungal and host cells.

Paraptosis cell death induction by the thiamine analog benfotiamine in leukemia cells.

Benfotiamine is a synthetic thiamine analogue that stimulates transketolase, a cellular enzyme essential for glucose metabolism. Currently, benfotiamine is used to treat diabetic neuropathy. We recently reported that oral benfotiamine induced a temporary but remarkable recovery from acute myeloid leukemia in an elderly patient who was ineligible for standard chemotherapy due to dementia and renal failure. In the present study we present evidences that benfotiamine possess antitumor activity against leukemia cells. In a panel of nine myeloid leukemia cell lines benfotiamine impaired the viability of HL-60, NB4, K562 and KG1 cells and also inhibited the growing of primary leukemic blasts. The antitumor activity of benfotiamine is not mediated by apoptosis, necrosis or autophagy, but rather occurs though paraptosis cell death induction. Mechanistic studies revealed that benfotiamine inhibited the activity of constitutively active ERK1/2 and concomitantly increased the phosphorylation of JNK1/2 kinase in leukemic cells. In addition, benfotiamine induced the down regulation of the cell cycle regulator CDK3 which resulted in G1 cell cycle arrest in the sensitive leukemic cells. Moreover, combination index studies showed that benfotiamine enhanced the antiproliferative activities of cytarabine against leukemia cells. These findings suggest that benfotiamine has antitumor therapeutic potential.

Wogonin induces apoptosis and endoplasmic reticulum stress in HL-60 leukemia cells through inhibition of the PI3K-AKT signaling pathway.

Wogonin is a flavonoid isolated from Scutellaria baicalensis root and has multiple pharmacological effects, including anticancer effects. Recent studies have shown that wogonin induces cell cycle arrest and reverses multi-drug resistance in the human K562 leukemia cell line. However, its pharmacological function in the apoptosis of leukemia cells remains unknown. Therefore, we hypothesized that wogonin can induce apoptosis in the HL-60 leukemia cell line. In the present study, the HL-60 cells were treated with different doses of wogonin (0-150 µM). Wogonin inhibited the viability of HL-60 cells in a dose-dependent and time-dependent manner. Flow cytometry and analyses of caspase and PARP-1 activation and the Bax/Bcl-2 ratio, demonstrated that the cytotoxic effect of wogonin on HL-60 cells was mediated by caspase-dependent and mitochondrial-dependent apoptosis. Wogonin also induced the expression of certain members of the endoplasmic reticulum (ER) stress pathway (CHOP, GRP94 and GRP78) and the activation of multiple branches of ER stress transducers (IRE1α, PERK-eIF2α and ATF6) in the HL-60 cells. In addition, wogonin reduced the phosphorylation of PI3K and AKT in the HL-60 cells. Furthermore, constitutive activation of AKT induced by adenoviral vectors inhibited the pro-apoptotic effects and ER stress induced by wogonin in the HL-60 cells. In summary, our results indicated that wogonin induced apoptosis and ER stress in HL-60 cells, which was mediated by the inhibition of the PI3K-AKT signaling pathway.

L-securinine induces apoptosis in the human promyelocytic leukemia cell line HL-60 and influences the expression of genes involved in the PI3K/AKT/mTOR signaling pathway

The Securinega alkaloids are a class of natural products isolated from plants of the Euphorbiaceae family. L-securinine induces apoptosis in the human promyelocytic leukemia cell line HL-60 indicating its potential as an efficient natural antitumor drug with low toxicity. The aim of the present study was to investigate the apoptotic effects of L-securinine on HL-60 cells and to explore its potential underlying molecular mechanism(s) as an antitumor agent. HL-60 cells were cultured with L-securinine. The proliferation and changes in cell morphology were evaluated by cell counting Kit-8 (CCK-8) assay and electron microscopy, respectively. Induction of apoptosis and cell cycle progression were investigated by flow cytometry. The PI3K/AKT/mTOR pathway gene expression was measured by quantitative PCR (qPCR). L-securinine decreased the viability of HL-60 cells in a dose- and time-dependent manner, with IC50 values at 24, 48 and 72 h post-treatment of 47.88, 23.85 and 18.87 µmol/l, respectively. Numerous apoptotic bodies were observed in the HL-60 cells treated with 25 µmol/l L-securinine for 48 h. L-securinine at 12.5, 25 and 50 µmol/l increased the rate of apoptosis in HL-60 cells, and G1/S phase progression was retarded. Furthermore, L-securinine induced downregulation of PI3K, AKT and mTOR gene expression and upregulation of PTEN gene expression in a dose-dependent manner. In conclusion, L-securinine induces apoptosis and inhibition of cell cycle progression in HL-60 cells by modulation of the PI3K/AKT/mTOR pathway gene expression. These observations indicate the potential of L-securinine as an antitumor agent.

CHEMICAL COMPOSITION, ANTIMICROBIAL, ANTIOXIDANT AND CYTOTOXIC ACTIVITIES OF <i>EUCALYPTUS CHAPMANIANA</i> GROWN IN IRAQ

The chemical composition of the essential oils extracted from immature flowers, leaves and seeds of Eucalyptus chapmaniana grown in Iraq were analyzed for the first time by gas chromatography/mass spectrometry. Twenty-four different compounds were identified and the predominant compound is eucalyptol, which accounted for 59.9, 55.6 and 8.6% of total compounds, respectively. To asses the possible therapeutic uses of the extracts, their antioxidant properties were assessed via DPPH free radical scavenging. The extracts showed significant antioxidant and antimicrobial activities against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Proteus volgaris, Staphylococcus aureus and Candida albicans. The cytoxicity of flower extract against the Human Leukemia (HL-60) cells was evaluated and the extracts significantly reduced the viability of HL-60 cells in a dose- and time-dependent response relationship. The results indicated that essential oils from immature flowers are highly cytotoxic to HL-60 cells and that their antitumor potential was confirmed.

20 Cardioprotection During Chemotherapy: A Case Study to Understand Intracellular Mechanisms to Combat the Cardiotoxicity of Sunitinib

Tyrosine Kinase inhibitor Sunitinib mediates its apoptotic anti-cancer effects by inhibiting intracellular signalling involved in tumour angiogenesis and cell proliferation. Unfortunately Sunitinib has revealed unwanted cardiotoxicity side-effects and investigations into...

Armillaria mellea component armillarikin induces apoptosis in human leukemia cells

Honey mushroom Armillaria mellea, a commonly used medicinal food in Asia, is an important component of traditional Chinese medicine “Tien-ma”. Armillarikin is a compound isolated from A. mellea with unclear biomedical functions. In this study, we found that armillarikin inhibited the viability of human leukemia K562, U937, and HL-60 cells in a concentration-dependent manner, causing cell death mainly attributable to apoptosis accompanied by reduction of mitochondrial transmembrane potential. Armillarikin induced cleavage of caspase-8, caspase-9, caspase-3, and caspase-3 substrate PARP. Armillarikin-induced growth inhibition and apoptosis were reversed by pan-caspase inhibitor Z-VAD-fmk, indicating a caspase-dependent effect. Moreover, armillarikin increased production of intracellular ROS. Prevention of ROS production attenuated armillarikin-induced apoptosis, suggesting mediation by ROS. In conclusion, armillarikin inhibited growth and induced apoptosis through a mechanism involving mitochondria dysfunction, caspase activation and ROS production in human leukemia K562, U937, and HL-60 cells.

Isolation of xanthones from adventitious roots of St. John’s Wort (Hypericum perforatum L.) and their antioxidant and cytotoxic activities

In this phytochemical study, 5 xanthones, 1,3,5,6-tetrahydroxyxanthone [1], 1,5,6-trihydroxy-3-methoxyxanthone [2], ferrxanthone [3], brasilixanthone B [4], and neolancerin [5] were isolated from adventitious roots of St. John’s wort (Hypericum perforatum L.). Compound 1–5 were evaluated for antioxidant activities using the intracellular reactive oxygen species (ROS) radical scavenging 2′,7′-dichlorfluorescein-diacetate (DCFDA) assay and for cytotoxic activity against the HL-60 human promyelocytic leukemia cells. Among them, compound 1–4 exhibited scavenging activity with inhibition values of 27.4–33.2% at 10 μM; compound 1, 2, and 4 reduced the viability of HL-60 cells significantly, with IC50 values of 31.5, 28.9, and 27.7 μM, respectively.

Effect of hydrostatic pressure on the viability of non-adherent HL-60 cells

We investigated the effect of hydrostatic pressure on the viability of non-adherent HL-60 cell line derived from leukemic cells over a high pressure range. The HL-60 cells are resistant to pressures of up to 100 MPa under pressurization for 20 min at 25°C. However, cell viability decreased markedly between 100 and 200 MPa, and almost all cells died above 200 MPa. In the case of pressures up to 25 MPa at 25°C for four days, the viability of HL-60 cells was inhibited by increasing the pressure above 20 MPa. Although high viability was observed between 1.6 and 2.0 MPa for adherent astrocytes, viability did not change over pressures up to 2.0 MPa in the case of non-adherent HL-60 cells. It is thought that the response of cells to pressure varies among cell types.

PHENOLIC CONTENT, ANTIOXIDANT, ANTIMICROBIAL AND CYTOTOXIC ACTIVITIES OF ETHANOLIC EXTRACT OF <i>SALIX ALBA</i>

The total phenolic content, antioxidant, antimicrobial and cytotoxic activities of hot ethanolic extract of Salix alba bark were investigated. The antioxidant properties and the total phenolic contents of the extract were assessed by 1, 1-Diphenyl- 2-Picrylhydrazyl (DPPH) free radical scavenging and Folin-Ciocalteu methods, respectively. The extract showed significant antioxidant activity and antimicrobial activities against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans. The highest effect was observed on C. albicans, followed by S. aureus then P. aeruginosa. While, Escherichia coli and Klebsiella pneumoniae were not affected. The cytoxicity of S. alba extract against the Human Leukemia (HL-60) cell line was evaluated, it had been noticed that the extract significantly reduced the viability of HL-60 cells in a dose- and time-dependent response relationship. Findings from the present study indicate that extract is highly cytotoxic to HL-60 cells. The antimicrobial and cytotoxic activities of S. alba extract seemed to be positively correlated with their antioxidant potentials.

Biogenic Silver Nanoparticles and its Antifungal Activity as a New Topical Transungual Drug

Silver nanoparticles production was monitored by UVVis and TEM micrograph and they were obtained as spherical and homogenous nanoparticles with a size of ~100 nm by photon correlation spectroscopy (PCS). Silver nanoparticles, in an IC80range of 1-2 μg/mL, showed significant antifungal activity againstT. rubrum. Cytotoxicity through hemolytic activity against erythrocytes and the viability of V79 fibroblast or HL60 cells showed less toxicity than amphotericin B. The disk diffusion test showed that the silver nanoparticles exerted a similar inhibition zone that amphotericin B by a synergistic effect when added at the same time againstT. rubrumculture.

Synergism between carnosic acid and arsenic trioxide on induction of acute myeloid leukemia cell apoptosis is associated with modulation of PTEN/Akt signaling pathway

To investigate the synergistic effects of carnosic acid (CA) with arsenic trioxide (As₂O₃) on proliferation and apoptosis in HL-60 human myeloid leukemia cells, and the major cellular signaling pathway involved in these effects. HL-60 cellular proliferation was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) analysis. Cell cycle distribution and apoptosis were monitored by flow cytometry. The activation of casepase-9, Bcl-2-associated agonist of cell death (BAD), p-BAD, p27, phosphatase and tensin homolog deleted on chromosome ten (PTEN), Akt, p-Akt was assessed by Western blot analysis. The expression of PTEN mRNA was tested by reverse transcription polymerase chain reaction (RT-PCR) analysis. CA reduced HL-60 cell viability in a dose- and time-dependent manner, and induced G1 arrest and apoptosis. Moreover, CA upregulated PTEN expression, blocked the Akt signaling pathway, subsequently inhibited phosphorylation of BAD, reactivated caspase-9, and elevated levels of p27. CA also augmented these effects of As₂O₃. CA might be a novel candidate of the combination therapy for leukemia treatment; these effects were apparently associated with the modulation of PTEN/Akt signaling pathway.

Lycorine induces cell-cycle arrest in the G0/G1 phase in K562 cells via HDAC inhibition

BackgroundLycorine, a natural alkaloid extracted from Amaryllidaceae, has shown various pharmacological effects. Recent studies have focused on the potential antitumor activity of lycorine. In our previous study, we found that lycorine decrease the cell viability of leukemia HL-60 cells and multiple myeloma KM3 cells and induces cell apoptosis. However, the effect and molecular mechanism of lycorine on human chronic myelocytic leukemia cells has yet to be determined.MethodsHuman chronic myelocytic leukemia cells K562 were treated with lycorine. Cell viability was monitored using the method of CCK-8. The histone deacetylase (HDAC) enzymatic activity was detected by HDAC colorimetric assay, and the cell cycle was analyzed by flow cytometry. The expression of cell-cycle related proteins were identified using Western blot.ResultsIn the present study, we further revealed that lycorine can inhibit the proliferation of K562 cells. Analysis of HDAC activity showed that lycroine decreases HDAC enzymatic activities in K562 cells in a dose-dependent manner. Inhibition of HDAC activity has been associated with cell-cycle arrest and growth inhibition. We evaluated the cell cycle distribution after lycorine treatment and found that lycorine causes cell-cycle arrest in the G0/G1 phase. To investigate the mechanism behind this cell cycle arrest, G1-related proteins were assayed by Western blot. After lycorine treatment, cyclin D1 and cyclin-dependent kinase 4 expressions were inhibited and retinoblastoma protein phosphorylation was reduced. Lycorine treatment also significantly upregulated the expression of p53 and its target gene product, p21.ConclusionsThese results suggest that inhibition of HDAC activity is responsible for at least part of the induction of cell-cycle arrest in the G0/G1 phase by lycorine and provide a mechanistic framework for further exploring the use of lycorine as a novel antitumor agent.

Inhibition of NF-κB Activation Augments the Effect of 5-Azacytidine On Acute Myeloid Leukemia Cell Line

Abstract 1369Dehydroxymethylepoxyquinomycin (DHMEQ) is a unique NF-kB inhibitor that is a 5-dehydroxymethyl derivative of novel compound epoxyquinomicin C and is currently under development for clinical use. We have shown that DHMEQ specifically binds to NF-kB having transactivation domain and inhibits NF-kB activation at the level of the nuclear translocation and the DNA binding. Constitutive activation of NF-kB has turned out to be a hallmark of various types of cancers originated from hematopoietic and other organs. We showed the effectiveness of DHMEQ in hematological malignancies with constitutive activation of NF-kB including multiple myeloma, chronic lymphocytic leukemia, adult T-cell leukemia, pleural effusion lymphoma and Hodgkin lmphoma. However, significance of NF-kB as a molecular target in acute myeloid leukemia (AML) is not well understood.Recently 5-azacytidine is widely used for the treatment of myelodysplastic syndrome and other cancers. 5-Azacytidine is a nucleoside-based DNA methyltransferase inhibitor that induces demethylation and gene reactivation. Therefore it is possible that 5-azacytidine induces molecules required for NF-kB activation. However, the effect of 5-azacytidine on NF-kB induction, which may antagonize the anti-cancer effect is poorly understood. In this study we examined the constitutive NF-kB activation and the effectiveness of DHMEQ on AML cell lines, HL-60, ML-2, HEL, K562, CMK and Meg0-1. We also examined the induction of NF-kB by 5-azacytidine and evaluated the combined treatment of AML cell lines by 5-azacytidine and DHMEQ.AML cell lines except for K562 showed constitutive activation of NF-κB consisting of RelA and p50 subcomponent. The NF-κB binding activity observed in AML cell lines were relatively modest compared to that observed in Jurkat cells treated with tumor necrosis factor (TNF). Treatment of AML cell lines with constitutive activation of NF-κB by DHMEQ inhibited NF-κB and significantly reduced their viability. Treatment with 5-azacytidine also significantly reduced the viability of AML cell lines, however K562 showed resistance against the treatment. Addition of DHMEQ enhanced the effect of 5-azacytidine on cell viability of HL-60 and CMK cells. The treatment with 5-azacytidine enhanced NF-kB activation although the induction was modest and DHMEQ abolished both constitutive and induced NF-kB activation in HL-60 and CMK cells.The results indicate that NF-κB is a molecular target of AML cells and DHMEQ is a potential compound for the treatment of AML. Although the NF-κB activity is relatively low compared to that in lymphoid malignancies, the constitutive activation of NF-κB in AML cell lines appears to play a significant role for their survival. The results also indicate that 5-azacytidine can reduce viability of AML cells and combined use of an NF-κB inhibitor augments the effect of 5-azacytidine by inhibiting constitutive and induced NF-κB. Since NF-κB cooperates with various transcription factors and supports the survival of cells, interruption of the crosstalk between NF-kB and molecules induced by 5-azacytidine might also be responsible for the combined effect of DHMEQ and 5-azacytidine. Disclosures:No relevant conflicts of interest to declare.

Ethyl Gallate Induces Apoptosis of HL-60 Cells by Promoting the Expression of Caspases-8, -9, -3, Apoptosis-Inducing Factor and Endonuclease G

Many phytochemicals have been recognized to have potential therapeutic efficacy in cancer treatment. In this study, we investigated ethyl gallate (EG) for possible proapoptotic effects in the human promyelocytic leukemia cell line, HL-60. We examined cell viability, morphological changes, DNA content and fragmentation, and expression of apoptosis-related proteins for up to 48 h after EG treatment. The results showed that EG induced morphological changes and DNA fragmentation and reduced HL-60 cell viability in a dose-dependent and time-dependent manner. Western blotting analysis indicated that EG-mediated HL-60 apoptosis mainly occurred through the mitochondrial pathway, as shown by the release of cytochrome c, apoptosis-inducing factor (AIF), and endonuclease G (Endo G), as well as the upregulation of Bcl-2-associated X protein (Bax). EG also activated the death receptor-dependent pathway of apoptosis by enhancing the expression of caspases-8, -9, and -3 and the Bcl-2 interacting domain (Bid). Collectively, our results showed that EG induces apoptosis in HL-60 via mitochondrial-mediated pathways.

Abstract 5640: Preclinical of assessment of oxidative stress and apoptotic mechanisms of garlic extract in the prevention of acute promyelocytic leukemia

Abstract INTRODUCTION: Garlic supplementation in diet has been shown to benefit patients with cancer. Recently, the pharmacological role of garlic in the prevention and treatment of cancer has received increasing attention. However, the mechanisms by which garlic extract (GE)-induced cytotoxicity, oxidative stress, and apoptosis in cancer cell remain largely unknown. OBJECTIVE: The present study was designed to use HL-60 cells as test model to evaluate whether or not GE-induced cytotoxicty and apoptosis in human leukemia (HL-60) cells is mediated through oxidative stress. METHODS: Human leukemia (HL-60) cells were treated with increasing concentrations of GE for 12 h. Cell survival was determined by MTT assay. The extent of oxidative cell/tissue damage was determined by measuring lipid peroxidation (malondialdehyde) concentrations by spectrophotometry. Cell apoptosis was measured by flow cytometry assessment (Annexin-V and caspase-3 assays) and DNA laddering analysis, respectively. RESULTS: Data obtained from the MTT assay indicated that GE significantly (p < 0.05) reduced the viability of HL-60 cells in a dose-dependent manner. We detected a significant (p < 0.05) increase in malondialdehyde (MDA) concentrations in GE-treated HL-60 cells compared to the control. Flow cytometry data showed a strong concentration-response relationship between GE exposure and Annexin-V positive HL-60 cells. Similarly, a statistically significant and dose-dependent increase (p <0.05) was recorded with regard to caspase-3 activity in HL-60 cells undergoing late apoptosis. These results were confirmed by data of DNA laddering assay showing a clear evidence of nucleosomal DNA fragmentation in GE-treated cells. CONCLUSION: Our finding indicates that GE-induced cytotoxicity and apoptosis in HL-60 cells are executed by cell death, phosphatidylserine externalization, activation of caspase-3, and nucleosomal DNA fragmentation under the overproduction of MDA, a by-product of lipid peroxidation and biomarker of oxidative stress. We conclude that GE at therapeutic concentrations induces cytotoxic effect and apoptosis in human leukemia (HL-60) cells through oxidative stress. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5640. doi:1538-7445.AM2012-5640

The Photocatalytic Inactivation Effect of Fe-Doped TiO2Nanocomposites on Leukemic HL60 Cells-Based Photodynamic Therapy

The Fe-doped TiO2nanocomposites synthesized by a deposition-precipitation method were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and UV-vis adsorption spectra and then were taken as a new “photosensitizer” for photodynamic therapy (PDT). The photocatalytic inactivation of Fe-doped TiO2on Leukemic HL60 cells was investigated using PDT reaction chamber based on LED light source, and the viability of HL60 cells was examined by Cell Counting Kit-8 (CCK-8) assay. The experimental results showed that the growth of leukemic HL60 cells was significantly inhibited by adding TiO2nanoparticles, and the inactivation efficiency could be effectively enhanced by the surface modification of TiO2nanoparticles with Fe doping. Furthermore, the optimized conditions were achieved at 5 wt% Fe/TiO2at a final concentration of 200 μg/mL, in which up to 82.5% PDT efficiency for the HL60 cells can be obtained under the irradiation of 403 nm light (the power density is 5 mW/cm2) within 60 minutes.

In vitro Assessment of Oxidative Stress and Apoptotic Mechanisms of Garlic Extract in the Treatment of Acute Promyelocytic Leukemia

Garlic supplementation in diet has been shown to be beneficial to cancer patients. Recently, its pharmacological role in the prevention and treatment of cancer has received increasing attention. However, the mechanisms by which garlic extract (GE) induces cytotoxicity, oxidative stress, and apoptosis in cancer cells remain largely unknown. The present study was designed to use HL-60 cells as a test model to evaluate whether or not GE-induced cytotoxicty and apoptosis in human leukemia (HL-60) cells is mediated through oxidative stress. Human leukemia (HL-60) cells were treated with different concentrations of GE for 12 hr. Cell survival was determined by MTT assay. The extent of oxidative cell/tissue damage was determined by measuring malondialdehyde (lipid peroxidation biomarker) concentrations by spectrophotometry. Cell apoptosis was measured by flow cytometry assessment (Annexin-V and caspase-3 assays) and agarose gel electrophoresis (DNA laddering assay). Data obtained from the MTT assay indicated that GE significantly (p < 0.05) reduced the viability of HL-60 cells in a concentration-dependent manner. We detected a significant (p < 0.05) increase in malondialdehyde (MDA) concentrations in GE-treated HL-60 cells compared to the control. Flow cytometry data showed a strong concentration-response relationship between GE exposure and Annexin-V positive HL-60 cells. Similarly, a statistically significant and concentration-dependent increase (p <0.05) were recorded with regard to caspase-3 activity in HL-60 cells undergoing late apoptosis. These results were confirmed by data of DNA laddering assay showing a clear evidence of nucleosomal DNA fragmentation in GE-treated cells. Our finding indicates that GE-induced cytotoxicity and apoptosis in HL-60 cells involve phosphatidylserine externalization, caspase-3 activation, and nucleosomal DNA fragmentation associated with the formation of MDA, a by-product of lipid peroxidation and biomarker of oxidative stress. At therapeutic concentrations, GE-induced cytotoxic and apoptotic effects in HL-60 cells is mediated by oxidative stress.