Human Leukemic Cell HL-60 Research Articles

Synthesis and Evaluation of Anticancer Activity of New 4-Acyloxy Derivatives of Robustic Acid.

In the present study, a series of 4-acyloxy robustic acid derivatives were synthesized and characterized for evaluation of their anti-cancer activity. The structures of these derivatives were elucidated by mass spectra (MS) nuclear magnetic resonance spectra (NMR). The single-crystal X-ray diffraction structure of one of these compounds was obtained, for further validation of the target compound structures. The anticancer activities of the target products were evaluated against human leukemic cells HL-60, human non-small cell lung carcinoma cells A-549, human hepatic carcinoma cells SMMC-7721, human hepatocellular carcinoma cells HepG2, and human cervical carcinoma cells Hela. Three compounds among them exhibited potent in-vitro cytotoxicity and excellent DNA topoisomerase I inhibitory activity, even at 0.1 mM concentrations. The most noteworthy observation was the minor toxicity of two of these compounds to normal cells, with an activity similar to the positive control in cancerous cells. A Surflex-Dock docking study was performed to investigate the topoisomerase I activity of all compounds. Of all the other compounds, the most sensitive compound was selected for further investigation of its effect on apoptosis induction and cell cycle regulation in HL-60 cells. Our results suggest that the anticancer effects of these compounds can be attributed to their pharmacological effects on topoisomerase I, cell apoptosis, and cell cycle. These findings suggest that robustic acid derivatives could be used as potential antitumor drugs.

The mechanistic antitumor study of myricanol 5-fluorobenzyloxy ether in human leukemic cell HL-60.

The aim of the study was to explore the growth inhibitory effect of myricanol 5-fluorobenzyloxy ether (5FEM) and the underlying mechanism in human leukemic cells HL-60. 5FEM was obtained by chemical modification of myricanol with fluorobenzyloxy ether at the OH(5) position. The cytotoxicity, cell apoptosis, cell cycle and the expression of key apoptosis-related genes in HL-60 were evaluated. 5FEM can significantly inhibited growth of HL-60 cells, increased the G2/M population and upregulated the expression of Bax, Fas, FasL, caspase-9 and p21 and downregulated that of Bcl-2 and survivin. The results enhance our understanding of 5FEM and aid the discovery of novel myricanol derivatives as potential antitumor agents.

Novel Porphyrin Conjugates with a Potent Photodynamic Antitumor Effect: Differential Efficacy of Mono‐ and Bis‐β‐cyclodextrin Derivatives In Vifro and In Vivo

In the present study we investigated the photosensitizing properties of two novel mono- and bis-cyclodextrin tetrakis (pentafluorophenyl) porphyrin derivatives in several tumor cell lines and in BALB/c mice bearing subcutaneously transplanted syngeneic mouse mammary carcinoma 4T1. Both studied sensitizers were localized mainly in lysosomes and were found to induce cell death by triggering apoptosis in human leukemic cells HL-60. In 4T1 and other cell lines both apoptotic and necrotic modes of cell death occurred depending on drug and light doses. Mono-cyclodextrin porphyrin derivative P(beta-CD)1 exhibited stronger in vitro phototoxic effect than bis-cyclodextrin derivative P(beta-CD)2. However, in vivo P(beta-CD)2 displayed faster tumor uptake with maximal accumulation 6 h after application, leading to complete and prolonged elimination of subcutaneous tumors within 3 days after irradiation (100 J cm(-2)). In contrast, P(beta-CD)1 uptake was slower (48 h) and the reduction of tumor mass was only transient, reaching the maximum at the 12 h interval when a favorable tumor-to-skin ratio appeared. Thus, P(beta-CD)2 represents a new photosensitizing drug displaying fast and selective tumor uptake, strong antitumor activity and fast elimination from the body.

Dehydrocrotonin and its derivative, dimethylamide-crotonin induce apoptosis with lipid peroxidation and activation of caspases-2, -6 and -9 in human leukemic cells HL60.

A variety of stimuli can induce cells to undergo apoptosis, with one of the most reproducible inducers being mild oxidative stress following exposure to anticancer agents. Apoptosis involves events mediated by cysteine proteases (caspases) that are classified as initiators (-8, -9 and -12) or executors (-2, -3, -6 and -7). In this study, we examined the mechanisms of apoptosis induced by dehydrocrotonin (DHC), a diterpene lactone isolated from the Amazonian plant Croton cajucara, and its synthetic derivative, dimethylamide-crotonin (DCR), in human HL60 promyelocytic leukemia cells. Flow cytometric analysis of HL60 cells after treatment for 72 h showed that DCR- and DHC-induced apoptosis, with maximum cell death at a concentration of 250 microM for both compounds. DCR and DHC were effective in triggering the activation of caspases-2, -6 and -9. The level of reduced glutathione (GSH) decreased, whereas there was an increase in thiobarbituric acid-reactive substance (TBARS) production and in mitochondrial swelling. These effects on mitochondrial swelling, GSH content and lipid peroxidation were abolished by cyclosporine A, an inhibitor of the membrane permeability transition. The cytotoxicity of DHC and DCR was prevented by a high concentration of GSH (15 mM) in the culture medium. These results indicate that DCR and DHC produced apoptosis partly by oxidative stress-induced lipid peroxidation, which triggered the caspase cascade, that lead to apoptotic cell death in HL60 cells. Based on the pattern of caspase activation, on the increase in mitochondrial swelling and on the inhibitory action of cyclosporine A, we conclude that DCR and DHC triggered apoptosis in HL60 cells probably through cytochrome c release and apoptosome formation.

Monocytic differentiation of HL60 cells induced by potent analogs of vitamin D3 precedes the G1/G0 phase cell cycle block

Abstract. Differentiation of mammalian cells is accompanied by reduced rates of proliferation and an exit from the cell cycle. Human leukemic cells HL60 present a widely used model of neoplastic cell differentiation, and acquire the monocytic phenotype when exposed to analogs of vitamin D3 (VD3). The maturation process is accompanied by two blocks in the cell cycle: an arrest in the G1/G0 phase, and a recently described G2+ M block. In this study we have analyzed the traverse of the cell cycle phases of the well‐differentiating HL60‐G cells exposed to one of ten analogs of VD3, and compared the cell cycle effects of each compound with its potency as a differentiation‐inducing agent. We found that in general there was a good correlation between the effects of these compounds on the cell cycle and on differentiation, but the best cell cycle predictor of differentiation potency was the extent of accumulation of the cells in the G2 compartment. All analogs induced a marked decrease in the mitotic index, and polynucleation of HL60 cells was produced, especially by compounds which were effective as inducers of differentiation. Time course studies showed that induction of differentiation was accompanied by a transient increase of the proportion of cells in the G2+ M compartment, but preceded the G1 to S, and the G2 compartment blocks. These studies indicate that complex changes in the cell cycle traverse accompany, but do not precede, the acquisition of the monocytic phenotype by HL60 cells.

Transforming growth factor-β1 modulates the effect of 1α,25-dihydroxyvitamin D3 on leukemic cells

The human leukemic cells HL-60, U937, KG-1 and THP-1 incubated with transforming growth factor-beta 1 (TGF-beta 1) were studied by examining cell surface antigens and macrophage-specific activities. The addition of 0.5 ng/ml (20 pM) of TGF-beta 1 with 1 alpha, 25-dihydroxyvitamin D3 [1 alpha, 25(OH)2D3] induced more Leu-M3 (CD14)-positive cells (approximately 80%) than 5 X 10(-8) M 1 alpha, 25(OH)2D3 alone did (30 to 50%), although original HL-60 cells did not express any Leu-M3 antigen at all. Tumor necrosis factor-alpha (TNF-alpha) with TGF-beta 1 and 1 alpha, 25(OH)2D3 was found to potentiate the expression of these surface antigens. Furthermore, the phagocytic activity was also induced strongly. The expression of CR3 (CD11b) antigen was also increased, and all Leu-M3-positive cells were found CR3-positive when HL-60, U937, and THP-1 cells were treated with these stimulants. In contrast, CR3 but not Leu-M3 was induced in KG-1 cells after the same treatment. This may indicate that the responsiveness of leukemic cells to TGF-beta 1 and 1 alpha, 25(OH)2D3 might vary depending on a differentiation stage of the target cells. Furthermore, K562 cells originated from a more undifferentiated precursor, were not able to respond to these two inducers. These results suggested that some of TGF-beta superfamily proteins might represent potent modulators in hematopoiesis, especially in the development of monocytes-macrophages or their precursors.