Human Myeloid Leukemia HL-60 Cells Research Articles

The PKM2 inhibitor shikonin enhances piceatannol-induced apoptosis of glyoxalase I-dependent cancer cells.

Glyoxalase I (GLO I), a major enzyme involved in the detoxification of the anaerobic glycolytic byproduct methylglyoxal, is highly expressed in various tumors, and is regarded as a promising target for cancer therapy. We recently reported that piceatannol potently inhibits human GLO I and induces the death of GLO I-dependent cancer cells. Pyruvate kinase M2 (PKM2) is also a potential therapeutic target for cancer treatment, so we evaluated the combined anticancer efficacy of piceatannol plus low-dose shikonin, a potent and specific plant-derived PKM2 inhibitor, in two GLO I-dependent cancer cell lines, HL-60 human myeloid leukemia cells and NCI-H522 human non-small-cell lung cancer cells. Combined treatment with piceatannol and low-dose shikonin for 48 h synergistically reduced cell viability, enhanced apoptosis rate, and increased extracellular methylglyoxal accumulation compared to single-agent treatment, but did not alter PKM1, PKM2, or GLO I protein expression. Taken together, these results indicate that concomitant use of low-dose shikonin potentiates piceatannol-induced apoptosis of GLO I-dependent cancer cells by augmenting methylglyoxal accumulation.

Antileukemic potential of Nile blue-mediated photodynamic therapy on HL60 human myeloid leukemia cells.

Photodynamic therapy (PDT) has received great attention over the past decade in the treatment of diseases such as leukemia which is a cancer of the blood and bone marrow cells that causes a significant number of deaths worldwide. In this study, it was aimed to investigate the effects of Nile blue-mediated PDT (NB-mediated PDT) on HL60 cells. The effect of NB-mediated PDT on cell proliferation was evaluated with cell volume analysis using flow cytometry at 24 h. Cell apoptosis, ROS production, mitochondrial membrane potential, and cell cycle analysis were evaluated using annexin V-FITC, H2DCFDA, JC-1, and PI staining, respectively, by flow cytometry and fluorescence microscopy. The morphological and ultrastructural analyses were examined by Giemsa staining and SEM. CD11b staining is used to determine the differentiation of leukemia cells. NB-mediated PDT induced an apoptotic response at 12.5 μM in HL60 cells. When Giemsa staining and SEM images were evaluated, apoptotic bodies, holes, and occasional folds were detected on the surfaces of cells in the NB-mediated PDT group. The NB-mediated PDT had no effect on the differentiation of leukemia cells, but this therapy affects the growth of HL60 cells in vitro, which may provide a new idea for removing leukemic cells from bone marrow intended for autologous transplant.

Green synthesis of copper oxide spindle like nanostructure using Hibiscus cannabinus flower extract for antibacterial and anticancer activity applications

In this study, CuO nanospindle synthesized using petal extract of Hibiscus cannabinus (H. cannabinus) was attempted to have better antibacterial activity against Gram-positive and Gram-negative bacteria. Cytotoxic activity was found to be 70 % against human acute myeloid leukemia HL60 cell line at 500 µg/ml. Morphological features of CuO was analyzed by scanning electron microscopy (SEM). Structural properties were analyzed by X-ray diffraction (XRD) pattern and the Fourier transform infrared (FTIR) spectrum of CuO provides additional evidence for the formation of monoclinic crystal structured CuO. Energy dispersive X-ray spectroscopy (EDAX) analysis exposed the pristine properties of CuO nanospindles.

Anti-leukemic activity of Cyperus rotundus L. on human acute myeloid leukemia HL-60 cells in vitro

Context: Acute myeloid leukemia (AML) is the most common form of acute leukemia. Currently, many people use medicinal herbs for the treatment of cancers. Nut grass (Cyperus rotundus L.) is a medicinal plant widely used in conventional medicine due to its role as an anti-cancer. Aims: To evaluate the effect of Cyperus rotundus tuber (CRT) ethanolic extract on cell proliferation, differentiation, cell cycle, and apoptotic of HL-60 cells. Methods: HL-60 cells line as a model for AML was cultured under the influence of CRT extract concentrations (35.4, 354, and 3540 µg/mL) for 48 h. Furthermore, the cell was subjected to carboxyfluorescein succinimidyl ester staining for proliferation, using a CD117 marker for differentiation. Annexin V-FITC and PI for cell cycle and apoptosis. The effect of this herb was studied by flow cytometry. The data were statistically analyzed with one-way ANOVA (p≤0.05) and the Tukey test using SPSS version 16 for Windows. Results: The results showed that the CRT inhibited proliferation activity, differentiation, cell cycle arrest, and apoptosis. Conclusions: The data clearly showed the potential anti-cancer activity of CRT on HL-60 cells and suggested that it could help develop promising therapeutic agents for AML treatments.

Novel benzo chromene derivatives: design, synthesis, molecular docking, cell cycle arrest, and apoptosis induction in human acute myeloid leukemia HL-60 cells

A series of benzo[h]chromenes, benzo[f]chromenes, and benzo[h]chromeno[2,3-d]pyrimidines were prepared. All the newly synthesised compounds were selected by National Cancer Institute for single-dose testing against 60 cell lines. Benzo[h]chromenes 5a and 6a showed promising anti-cancer activity and selected for the five-dose testing. Compounds 5a and 6a suppressed cell growth in HL-60 by the induction of cell cycle arrest, which was confirmed using flow cytometry and Annexin V-FITC/PI assays showed at the G1/S phase by regulating the expression of CDK-2/CyclinD1, triggering cell apoptosis by activating both the extrinsic (Fas/Caspase 8) and intrinsic (Bcl-2/Caspase 3) apoptosis pathways, which were determined by the western blot. Benzo[h]chromenes 5a and 6a decreased the protein expression levels of Bcl-2, CDK-2, and CyclinD1 and increased the expression of caspase 3, caspase 8, and Fas. In silico molecular analysis of compounds 5a and 6a in CDK-2 and Bcl-2 was performed.

Antiproliferative Activity and Apoptotic Potential of Curcumin on Human Acute Myeloid Leukemia Cell Line (HL-60)

Curcuma Longa or also known as turmeric is a prominent natural remedy in Asia that has been utilized to heal diseases for decades. It has been demonstrated to have substantial biological activities, including anticarcinogenic, antimutagenic, antioxidant, anti-inflammatory, anti-infectious, hypocholesterolemic, and chemopreventive properties. Curcumin is a therapeutic substance extracted from Curcuma Longa that is thought to have anti-cancer properties against a variety of cancer types. However, its anti-cancer potential on acute myeloid leukemia (AML) remains uncertain [1,2]. 
 
 The objective of this intervention study was to examine the anti-proliferative and apoptotic effects of curcumin on the HL-60 cell line of acute myeloid leukemia. A stock solution of pure curcumin compound was obtained by dissolving it in dimethyl sulfide (DMSO). HL-60 cells were treated with six different concentrations which were 100, 50, 25, 12.5, 6.25, 3.125 µg/ml and incubated at three distinct incubation period (24, 48 and 72 hours). The in vitro cell viability was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and quantified using a microplate reader at 570 nm. Acridine orange (AO) and propidium iodide (PI) staining were employed to evaluate morphological changes. 
 
 MTT assays results show that curcumin has a high cytotoxicity effect on HL-60 cells. The maximal half inhibitory concentration (IC50) value of curcumin was consistently decreased when the incubation time increased. The IC50 of curcumin on HL-60 cells were reported to be 13, 8, and 3.5 µg/ml at 24, 48 and 72 hours of incubation, respectively. There was a significantly different IC50 value (p<0.05) of curcumin between the incubation periods (Figure 1). The morphological alteration was shown in AO/PI staining by the appearance of early apoptosis, late apoptosis, and necrotic cells.
 These findings illustrated that curcumin revealed an effective anti-cancer action on human acute myeloid leukemia HL-60 cell line. Further research is required to determine the mechanism of cell death in HL-60 cells treated with pure curcumin compound.
 
 In conclusion, the study revealed the role of putative targeted genes in the biological mechanism in gout pathogenesis has provides insight of the potential biomarkers in developing the personalized medicine better treatment for gout patient in ensuring better patient healthcare.

A cytotoxic survey on 2-amino-1H-imidazol based synthetic marine sponge alkaloid analogues.

Here, we describe the synthesis and biologic activity evaluation of 20 novel synthetic marine sponge alkaloid analogues with 2-amino-1H-imidazol (2-AI) core. Cytotoxicity was tested on murine 4T1 breast cancer, A549 human lung cancer, and HL-60 human myeloid leukemia cells by the resazurin assay. A total of 18 of 20 compounds showed cytotoxic effect on the cancer cell lines with different potential. Viability of healthy human fibroblasts and peripheral blood mononuclear cells upon treatment was less hampered compared to cancer cell lines supporting tumor cell specific cytotoxicity of our compounds. The most cytotoxic compounds resulted the following IC50 values 28: 2.91 µM on HL-60 cells, and 29: 3.1 µM on 4T1 cells. The A549 cells were less sensitive to the treatments with IC50 15 µM for both 28 and 29. Flow cytometry demonstrated the apoptotic effect of the most active seven compounds inducing phosphatidylserine exposure and sub-G1 fragmentation of nuclear DNA. Cell cycle arrest was also observed. Four compounds caused depolarization of the mitochondrial membrane potential as an early event of apoptosis. Two lead compounds inhibited tumor growth in vivo in the 4T1 triple negative breast cancer and A549 human lung adenocarcinoma xenograft models. Novel marine sponge alkaloid analogues are demonstrated as potential anticancer agents for further development.

Overexpressed fibroblast growth factor receptors increase 1,25-dihydroxyvitamin D-dependent differentiation of acute myeloid leukemia cells

Many malignancies are driven by mutations within the gene for fibroblast growth factor receptor 1 (FGFR1). Previously, we have shown that signal transduction from the FOP2–FGFR1 fusion protein in acute myeloid leukemia KG1 cells is responsible for a low level of expression of the vitamin D receptor gene. In this paper, we address whether other fibroblast growth factor receptors regulate the vitamin D receptor (VDR) gene. We used the human myeloid leukemia U937 and HL60 cells, the bone cancer cell line U2OS, and cell transfection methods to answer the question. For myeloid leukemia cells, overexpression of FGFRs 1–3 genes caused a shift towards monocytic differentiation; this was extracellular regulated kinase (Erk) 1,2-dependent. Overexpression of FGFRs 1–3 genes also upregulated expression of the VDR gene, further sensitizing these cells to 1,25-dihydroxyvitamin D-induced monocyte differentiation. When we increased expression in bone cells, fibroblast growth factor receptors did not upregulate VDR gene expression, nor influence the activity of VDR. Fibroblast growth factor receptors are overexpressed in many neoplasms. Therefore, it may be reasonable to use vitamin D analogs to treat these cancers, to activate VDR and drive cell differentiation.

Abstract 3500: AUR103 an oral small molecule CD47 antagonist in combination with azacytidine and bortezomib exhibits potent anti-tumor activity in myeloma and leukemia models in vitro and in vivo

Abstract The CD47/signal regulatory protein alpha axis is a critical regulator of myeloid cell activation and serves as an immune checkpoint for macrophage mediated phagocytosis. Targeting CD47-SIRPα axis is emerging as one of the promising new immunotherapy approaches that targets innate immune response. Number of clinical trials are in progress to evaluate CD47/SIRPα blocking therapies. Most of these molecules are either anti-CD47 antibodies or SIRPα-Fc recombinant proteins. We have developed a novel small molecule CD47 antagonist, AUR103 as a therapeutic agent for solid and hematological cancers. AUR103 is efficacious as a single agent in tumors with high expression of “eat-me” signals and synergizes well in combination with tumor-targeting antibodies. We hypothesized that agents capable of inducing “eat-me” signals such as calreticulin (CRT) a pro-phagocytic signal, will synergize with AUR103 to enhance phagocytosis and antitumor activity. Here, we report the anti-tumor efficacy of AUR103 in combination with azacytidine and bortezomib in acute myeloid leukemia and multiple myeloma model of cancer, respectively.In the phagocytosis assay, HL-60 human myeloid leukemia or NCI-H929 human multiple myeloma cells were treated with azacytidine or bortezomib for 48 hours. Cells were stained with CFSE and were further treated with AUR103. Cells were then added to human macrophages and allowed to undergo phagocytosis. Phagocytosis of target cells was measured by detecting cells that were double positive for APC and CFSE by FACS. HL-60 cells were orthotopically implanted in NOD SCID mice while NCI-H929 multiple myeloma cells were sub-cutaneously implanted in NOD SCID mice. Tumor bearing mice were treated with AUR103 (10 and 30 mg/kg, b.i.d, and po) as a single agent or in combination with azacytidine (5 mg/kg i.p., twice weekly) or bortezomib (0.4 mg/kg i.v., twice weekly). AUR103 in combination with azacytidine and bortezomib significantly enhanced phagocytosis of HL-60 and NCI-H929 tumor cells, respectively when compared to individual treatments. In the combination efficacy studies, AUR103 combination treatments with azacytidine and bortezomib were well tolerated without any signs of toxicity. In the HL-60 orthotopic model, AUR103 combination with azacytidine significantly reduced the engraftment of HL-60 tumor cells. AUR103 combination with bortezomib resulted in enhanced tumor growth inhibition in NCI-H929 tumor model when compared to individual treatments. These results demonstrate the therapeutic potential of AUR103 in combination with agents that are capable of inducing “eat-me” or pro-phagocytic signals. Citation Format: Girish C. Daginakatte, Sasikumar Pottayil, Sudarshan Naremaddepalli, Gundala Chennakrishnareddy, Prasad Bilugudi, Sai Krishna Tangella, Sandeep Patil, Nagesh Gowda, Kiran Aithal, Wesley Roy Balasubramanian, Amit Dhudashiya, Samiulla Dodheri, Kavitha Nellore, Susanta Samajdar, Murali Ramachandra. AUR103 an oral small molecule CD47 antagonist in combination with azacytidine and bortezomib exhibits potent anti-tumor activity in myeloma and leukemia models in vitro and in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3500.

MAP kinase-dependent autophagy controls phorbol myristate acetate-induced macrophage differentiation of HL-60 leukemia cells

We investigated the mechanisms and the role of autophagy in the differentiation of HL-60 human acute myeloid leukemia cells induced by protein kinase C (PKC) activator phorbol myristate acetate (PMA). PMA-triggered differentiation of HL-60 cells into macrophage-like cells was confirmed by cell-cycle arrest accompanied by elevated expression of macrophage markers CD11b, CD13, CD14, CD45, EGR1, CSF1R, and IL-8. The induction of autophagy was demonstrated by the increase in intracellular acidification, accumulation/punctuation of autophagosome marker LC3-II, and the increase in autophagic flux. PMA also increased nuclear translocation of autophagy transcription factors TFEB, FOXO1, and FOXO3, as well as the expression of several autophagy-related (ATG) genes in HL-60 cells. PMA failed to activate autophagy inducer AMP-activated protein kinase (AMPK) and inhibit autophagy suppressor mechanistic target of rapamycin complex 1 (mTORC1). On the other hand, it readily stimulated the phosphorylation of mitogen-activated protein (MAP) kinases extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) via a protein kinase C-dependent mechanism. Pharmacological or genetic inhibition of ERK or JNK suppressed PMA-triggered nuclear translocation of TFEB and FOXO1/3, ATG expression, dissociation of pro-autophagic beclin-1 from its inhibitor BCL2, autophagy induction, and differentiation of HL-60 cells into macrophage-like cells. Pharmacological or genetic inhibition of autophagy also blocked PMA-induced macrophage differentiation of HL-60 cells. Therefore, MAP kinases ERK and JNK control PMA-induced macrophage differentiation of HL-60 leukemia cells through AMPK/mTORC1-independent, TFEB/FOXO-mediated transcriptional and beclin-1-dependent post-translational activation of autophagy.

Antileukemic Potential Of Nile Blue Mediated Photodynamic Therapy on Hl60 Human Myeloid Leukemia Cells

Antileukemic Potential Of Nile Blue Mediated Photodynamic Therapy on Hl60 Human Myeloid Leukemia Cells

Xanthohumol Induces ROS through NADPH Oxidase, Causes Cell Cycle Arrest and Apoptosis.

Reactive oxygen species (ROS) are either toxic in excess or essential for redox signalling at the physiological level, which is closely related to the site of generation. Xanthohumol (XN) is an important natural product of hops (Humulus lupulus L.) and was reported to induce ROS in mitochondria. While in the present study, our data indicate that NADPH oxidase (NOX) is another site. In human acute myeloid leukemia HL-60 cells, we first identified that cell proliferation was inhibited by XN without affecting viability, and this could be alleviated by the antioxidant N-acetyl-L-cysteine (NAC); cell cycles were blocked at G1 phase, apoptosis was induced in a dose-dependent manner, and malondialdehyde (MDA) content was upregulated. XN-induced ROS generation was detected by flow cytometry, which can be inhibited by diphenyleneiodonium chloride (DPI, a NOX inhibitor), while not by NG-methyl-L-arginine acetate (L-NMMA, a nitric oxide synthase inhibitor). The involvement of NOX in XN-induced ROS generation was further evaluated: immunofluorescence assay indicated subunits assembled in the membrane, and gp91phox knockdown with siRNA decreased XN-induced ROS. Human red blood cells (with NOX, without mitochondria) were further selected as a cell model, and the XN-induced ROS and DPI inhibiting effects were found again. In conclusion, our results indicate that XN exhibits antiproliferation effects through ROS-related mechanisms, and NOX is a source of XN-induced ROS. As NOX-sourced ROS are critical for phagocytosis, our findings may contribute to the anti-infection and anti-inflammatory effect of XN.

Piceatannol, a Structural Analog of Resveratrol, Is an Apoptosis Inducer and a Multidrug Resistance Modulator in HL-60 Human Acute Myeloid Leukemia Cells.

Acute myeloid leukemia is characterized by uncontrolled clonal proliferation of abnormal myeloid progenitor cells. Despite recent advances in the treatment of this disease, the prognosis and overall long-term survival for patients remain poor, which drives the search for new chemotherapeutics and treatment strategies. Piceatannol, a polyphenolic compound present in grapes and wine, appears to be a promising chemotherapeutic agent in the treatment of leukemia. The aim of the present study was to examine whether piceatannol induces autophagy and/or apoptosis in HL-60 human acute myeloid leukemia cells and whether HL-60 cells are able to acquire resistance to piceatannol toxicity. We found that piceatannol at the IC90 concentration of 14 µM did not induce autophagy in HL-60 cells. However, it induced caspase-dependent apoptosis characterized by phosphatidylserine externalization, disruption of the mitochondrial membrane potential, caspase-3 activation, internucleosomal DNA fragmentation, PARP1 cleavage, chromatin condensation, and fragmentation of cell nuclei. Our findings also imply that HL-60 cells are able to acquire resistance to piceatannol toxicity via mechanisms related to MRP1 activity. Our results suggest that the use of piceatannol as a potential chemotherapeutic agent may be associated with the risk of multidrug resistance, warranting its use in combination with other chemotherapeutic agents.

ZEB2 Knock-down Induces Apoptosis in Human Myeloid Leukemia HL-60 Cells.

Acute myeloid leukemia (AML) is the most prevalent type of cancer in the adult hematopoietic system. Conventional therapies are associated with unfavorable side effects in individuals diagnosed with AML. These after-effects with partial remission reflect the urgent need for novel therapeutic approaches for inducing apoptosis, specifically in malignant cells, without affecting other cells. As a transcription factor (TF), ZEB2 (Zinc Finger E-Box Binding Homeobox 2) regulates the expression of specific genes in normal conditions. However, increased expression of ZEB2 is reported in various cancers, especially in AML, which is related to a higher degree of apoptosis inhibition of malignant cells. In this work, the role of ZEB2 in apoptosis inhibition is surveyed through ZEB2 specific knocking-down in human myeloid leukemia HL-60 cells. Transfection of HL-60 cells was conducted using ZEB2-siRNA at concentrations of 20, 40, 60, and 80 pmol within 24, 48, and 72 h. After determining the optimum dose and time, flow cytometry was used to measure the apoptosis rate. The MTT assay was also utilized to evaluate the cytotoxic impact of transfection on the cells. The expression of candidate genes was measured before and after transfection using qRT-PCR. According to obtained results, suppression of ZEB2 expression through siRNA was associated with the induction of apoptosis, increased pro-apoptotic, and decreased anti-apoptotic gene expression. Transfection of ZEB2-siRNA was also associated with reduced cell proliferation and viability. Our study results suggest that ZEB2 suppression in myeloid leukemia cells through apoptosis induction could be a proper therapeutic method.

L, D-Polydeoxyribonucleotides to provide an essential inhibitory effect on DNA polymerase β of human myeloid leukemia HL60 cells

The inhibitory effect of D and L-polynucleotides of a given length (40-50n) on the catalytic activity of DNA polymerase β isolated from chromatin cells of acute myeloid leukemia HL-60 was evaluated. The synthesized L enantiomer was found to have a higher inhibitory activity than the synthesized and isolated D enantiomers of polynucleotides. The work also proposes a biophysical model that describes this effect.

Combination of diethyldithiocarbamate with 12-O-tetradecanoyl phorbol-13-acetate inhibits the growth of human myeloid leukemia HL-60 cells in vitro and in xenograft model.

12-O-tetradecanoylphorbol-13-acetate (TPA), is a major active constituent of the seed oil of Croton tiglium L., has pharmacological activity for the treatment of acute myeloid leukemia patients. Diethyldithiocarbamate (DTC) is a potent inhibitor of NF-κB show activity of anticancer. In this study, we determined the effect of DTC and TPA in combination on HL-60 cells cultured in vitro and in vivo. In this study, we have shown that DTC and TPA synergistically inhibited the growth of HL-60 cells and strongly induced apoptosis in the cells. Mechanistic studies showed that the combined effects of DTC and TPA were associated with a decrease in Bcl-2. The animal experiment showed that the combination of DTC and TPA more potently inhibited the growth of HL-60 tumors than either agent alone. Our results indicate that the administration of TPA and DTC in combination may be an effective strategy for inhibiting the growth of acute myeloid leukemia cells.

Axolotl Ambystoma mexicanum extract induces cell cycle arrest and differentiation in human acute myeloid leukemia HL-60 cells.

Acute myeloid leukemia is the most common form of acute leukemia in adults, constituting about 80% of cases. Although remarkable progress has been made in the therapeutic scenario for patients with acute myeloid leukemia, research and development of new and effective anticancer agents to improve patient outcome and minimize toxicity is needed. In this study, the antitumor activity of axolotl (AXO) Ambystoma mexicanum crude extract was assessed in vitro on the human acute myeloid leukemia HL-60 cell line. The anticancer activity was evaluated in terms of ability to influence proliferative activity, cell viability, cell cycle arrest, and differentiation. Moreover, gene expression analysis was performed to evaluate the genes involved in the regulation of these processes. The AXO crude extract exhibited antiproliferative but not cytotoxic activities on HL-60 cells, with cell cycle arrest in the G0/G1 phase. Furthermore, the AXO-treated HL-60 cells showed an increase in both the percentage of nitroblue tetrazolium positive cells and the expression of CD11b, whereas the proportion of CD14-positive cells did not change, suggesting that extract is able to induce differentiation toward the granulocytic lineage. Finally, the treatment with AXO extract caused upregulation of CEBPA, CEBPB, CEBPE, SPI1, CDKN1A, and CDKN2C, and downregulation of c-MYC. Our data clearly show the potential anticancer activity of Ambystoma mexicanum on HL-60 cells and suggest that it could help develop promising therapeutic agents for the treatment of acute myeloid leukemia.

Cytotoxic activity of dimeric acridone alkaloids derived from Citrus plants towards human leukaemia HL-60 cells.

Acridone alkaloids from Citrus and their derivatives show various kinds of biological activity. However, the anticancer activities of dimeric acridone alkaloids with unique structures and the molecular mechanism of these effects are poorly understood. We investigated the cytotoxicity effects of dimeric acridone alkaloids isolated from Marsh grapefruit on human myeloid leukaemia HL-60 cells. Of the six dimeric acridone alkaloids tested, citbismine-E, the most potent, dose- and time-dependently decreased HL-60 cell viability by inducing apoptosis. The treatment of HL-60 cells with citbismine-E yielded a significant increase in levels of intracellular reactive oxygen species (ROS). Citbismine-E lowered the mitochondrial membrane potential and increased the activities of caspase-9 and -3. In addition, citbismine-E-induced apoptosis, decrease in mitochondrial membrane potential and caspase activation were significantly alleviated by pretreatment of the cells with antioxidant N-acetylcysteine (NAC). Citbismine-E induced intrinsic caspase-dependent apoptosis through ROS-mediated c-Jun N-terminal kinase activation. Citbismine-E-induced production of oxidative stress biomarkers, malondialdehyde and 8-hydroxy-2'-deoxyguanosine was also attenuated by pretreatment with NAC. Citbismine-E is a powerful cytotoxic agent against HL-60 cells that acts by inducing mitochondrial dysfunction-mediated apoptosis through ROS-dependent JNK activation. Citbismine-E also induced oxidative stress damage via ROS-mediated lipid peroxidation and DNA damage in HL-60 cells.

Anticancer effects of an extract from a local planarian species on human acute myeloid leukemia HL-60 cells in vitro

Current anti-cancer drugs can cause many undesirable side effects to patients. Thus, there is a constant need to develop alternative therapeutic drugs. Bioactive compounds derived from natural products including animals, plants and microorganisms are being actively studied as sources for anticancer treatments. Freshwater planarians are important models for stem cell research and regeneration. However, to date, no studies on the biological activities of planaria extracts on cancer have been published. The aim of this study was to examine the potential antitumoral activity of the extract from planaria species-Malta (PSM) on human acute myeloid leukemia (AML) HL-60 cells. Antiproliferative activity was studied in terms of proliferation, apoptosis and differentiation. The expression of genes involved in the regulation of these important cellular processes was also analyzed using real-time PCR. PSM extract exhibited a selective cytotoxic effect on HL-60 cells when compared to normal lymphocytes. Furthermore, cell cycle analysis and Annexin V/PI assay showed that the extract induced apoptosis in HL-60 cells. The PSM extract induced myeloid differentiation with HL-60 cells showing a decreased nucleo/cytoplasmic ratio, an increase in nitroblue tetrazolium-positive cells, and CD11b- and CD14-positive cells. Finally, we also found that the PSM extract increased the expression of CEBPA, CEBPB, CEBPE, SPI1, BAX, CDKN1A and CDKN2C; whereas it reduced the expression of c-MYC and BCL2.This is the first study to reveal the antiproliferative, cytotoxic, and differentiation potential of PSM on HL-60 cells and suggests that it may have considerable potential for development as a novel natural product-based anticancer agent against AML.

A New Hybrid δ-Lactone Induces Apoptosis and Potentiates Anticancer Activity of Taxol in HL-60 Human Leukemia Cells.

In the search for new drug candidates, researchers turn to natural substances isolated from plants which may be either used directly or may serve as a source for chemical modifications. An interesting strategy in the design of novel anticancer agents is based on the conjugation of two or more biologically active structural motifs into one hybrid compound. In this study, we investigated the anticancer potential of 4-benzyl-5,7-dimethoxy-4-methyl-3-methylidene-3,4-dihydro-2H-chroman-2-one (DL-247), a new hybrid molecule combining a chroman-2-one skeleton with an exo-methylidene bond conjugated with a carbonyl group, in human myeloid leukemia HL-60 cell line. The cytotoxicity of the new compound was tested using MTT assay. The effect of DL-247 on cell proliferation and apoptosis induction were studied by flow cytometry, fluorometric assay and ELISA analysis. DL-247 displayed high cytotoxic activity (IC50 = 1.15 µM, after 24 h incubation), significantly inhibited cell proliferation and induced apoptosis by both, the intrinsic and extrinsic pathways. A combination of DL-247 with taxol exhibited a strong synergistic effect on DNA damage generation, apoptosis induction and inhibition of cell growth.