Cytotoxicity In Human Cancer Cells Research Articles

Synthesis, Structural Characterization, Optical Properties, and Biological Potency of Co(II), Cu(II), and Cd(II) Complexes With Heterocyclic Thiosemicarbazide Ligand: Insights From Molecular Docking Studies

ABSTRACTA novel heterocyclic thiosemicarbazide ligand, [(Z)‐N‐(2‐oxoindolin‐3‐ylidene)nicotinohydrazide] (H2L), and its Co(II), Cu(II), and Cd(II) metal chelates were synthesized and characterized using a variety of analytical methods, including elemental analysis, FT‐IR, UV–Visible spectroscopy, EI‐mass, fluorescence spectroscopy, X‐ray powder diffraction, and TGA. The structures and geometries of the complexes were determined using these methods as [Co2(H2L)2Cl2(H2O)4]·2H2O, [Cu(H2L)2Cl2(H2O)2]·2H2O, and [Cd(H2L)2Cl2(H2O)2], all having octahedral geometry. The particulate diameters for [Co2(H2L)2Cl2(H2O)4]·2H2O, [Cu(H2L)2Cl2(H2O)2]·2H2O, and [Cd(H2L)2Cl2(H2O)2] were 192.68, 68.48, and 192.74 nm, respectively using Debye–Scherrer equation and FWHM approach. The corresponding FWHM values were 0.0078, 0.0217, and 0.0075, whereas the crystal strain was calculated as (ε) = 0.0018, 0.0056, and 0.0054, and the dislocation density (δ) as 2.69 × 10−5, 2.13 × 10−4, 2.69 × 10−5 Å−2. Quantum chemical calculations for the ligand and its solid metal complexes were carried out utilizing DFT with the DMOL3 module. Furthermore, the optical sensing response of the free ligand H2L to Co(II), Cu(II), and Cd(II) ions was investigated, revealing that the presence of these metal ions enhanced the fluorescence spectra of the ligand. Additionally, the antibacterial effects of these compounds, as well as their cytotoxicity in human cancer cells, were investigated. Compared to its metal complexes, the ligand, H2L exhibits increased antibacterial activity against various bacteria. Tests on HepG‐2 and MCF‐7 cells were conducted to evaluate the compounds' anticancer efficacy against the standard, Doxorubicin. The ligand, H2L, demonstrated greater cytotoxicity against the HepG‐2 cell line than its metal complexes. Docking experiments were conducted to assess the interaction of the ligand and its complexes with HepG‐2 (PDB ID: 2OH4) and MCF‐7 (PDB ID: 3W2S) cells, using the XP glide technique and Schrödinger suite software.

Synthesis of Novel Pyrazole-Oxindole Conjugates with Cytotoxicity in Human Cancer Cells via Apoptosis.

A novel series of pyrazole-oxindole conjugates were prepared and characterized as potential cytotoxic agents by FT-IR, NMR and HR-MS. The cytotoxic activity of these compounds was tested in the Jurkat acute T cell leukemia, CEM acute lymphoblastic leukemia, MCF10 A mammary epithelial and MDA-MB 231 triple negative breast cancer cell lines. Among the tested conjugates, 5-methyl-3-((3-(1-phenyl)-3-(p-tolyl)-1H-pyrazol-4-yl)methylene)indolin-2-one 6h emerged as the most cytotoxic with a CC50 of 4.36+/-0.2 μM against Jurkat cells. The mechanism of cell death induced by 6h was investigated through the Annexin V-FITC assay via flow cytometry. Reactive oxygen species (ROS) accumulation, mitochondrial health and the cell cycle progression were also evaluated in cells exposed to 6h. Results demonstrated that 6h induces apoptosis in a dose-response manner, without generating ROS and/or altering mitochondrial health. In addition, 6h disrupted the cell cycle distribution causing an increase in DNA fragmentation (Sub G0-G1), and an arrest in the G0-G1 phase. Taken together, the 6h compound revealed a strong potential as an antineoplastic agent evidenced by its cytotoxicity in leukemia cells, the activation of apoptosis and restriction of the cell cycle progression.

An unexpected in-solution instability of diiodido analogue of picoplatin complicates its biological characterization.

Complex cis-[PtI2(NH3)(pic)] (1; pic = 2-methylpyridine), a diiodido analogue of clinically studied picoplatin (2), is unstable in solution, which is intriguingly connected with the release of its pic ligand. This observation complicates the biological testing of e.g. cytotoxicity in human cancer cells for 1.

Antimicrobial Peptides as Anticancer Agents: Functional Properties and Biological Activities.

Antimicrobial peptides (AMPs), or host defense peptides, are small cationic or amphipathic molecules produced by prokaryotic and eukaryotic organisms that play a key role in the innate immune defense against viruses, bacteria and fungi. AMPs have either antimicrobial or anticancer activities. Indeed, cationic AMPs are able to disrupt microbial cell membranes by interacting with negatively charged phospholipids. Moreover, several peptides are capable to trigger cytotoxicity of human cancer cells by binding to negatively charged phosphatidylserine moieties which are selectively exposed on the outer surface of cancer cell plasma membranes. In addition, some AMPs, such as LTX-315, have shown to induce release of tumor antigens and potent damage associated molecular patterns by causing alterations in the intracellular organelles of cancer cells. Given the recognized medical need of novel anticancer drugs, AMPs could represent a potential source of effective therapeutic agents, either alone or in combination with other small molecules, in oncology. In this review we summarize and describe the properties and the mode of action of AMPs as well as the strategies to increase their selectivity toward specific cancer cells.

Naphthalimide-based macrophage nucleus imaging probes

The photophysical properties of naphthalimide-based fluorophores can be easily tuned by chemical manipulation of the substituents on that privileged scaffold. Replacement of a OMe group at position 6 in 2-(hydroxyl)ethyl-naphthalimide derivatives by diverse amines, including 2-(hydroxyl)ethylamine, trans-(4-acetamido)cyclohexylamine and azetidine increases the solvatochromic (ICT) character, while this replacement in 2-(dimethylamino)ethyl-naphthalimide analogues (PET fluorophores) decrease their solvent polarity sensitivity or even reversed them to solvatochromic fluorophores. These fluorophores resulted macrophage nucleus imaging probes, which bind DNA as intercalants and showed low cytotoxicity in human cancer cells.

백합 구근 추출물의 항산화 활성 및 인체 암세포에 대한 독성효과

백합 구근 추출물의 항산화 활성 및 인체 암세포에 대한 독성효과

Aglycone Ebselen and β-d-Xyloside Primed Glycosaminoglycans Co-contribute to Ebselen β-d-Xyloside-Induced Cytotoxicity.

Most β-d-xylosides with hydrophobic aglycones are nontoxic primers for glycosaminoglycan assembly in animal cells. However, when Ebselen was conjugated to d-xylose, d-glucose, d-galactose, and d-lactose (8A-D), only Ebselen β-d-xyloside (8A) showed significant cytotoxicity in human cancer cells. The following facts indicated that the aglycone Ebselen and β-d-xyloside primed glycosaminoglycans co-contributed to the observed cytotoxicity: 1. Ebselen induced S phase cell cycle arrest, whereas 8A induced G2/M cell cycle arrest; 2. 8A augmented early and late phase cancer cell apoptosis significantly compared to that of Ebselen and 8B-D; 3. Both 8A and phenyl-β-d-xyloside primed glycosaminoglycans with similar disaccharide compositions in CHO-pgsA745 cells; 4. Glycosaminoglycans could be detected inside of cells only when treated with 8A, indicating Ebselen contributed to the unique property of intracellular localization of the primed glycosaminoglycans. Thus, 8A represents a lead compound for the development of novel antitumor strategy by targeting glycosaminoglycans.

Combining proton or photon irradiation with epothilone B. An in vitro study of cytotoxicity in human cancer cells

Recently, the use of proton beams in cancer therapy is becoming widespread, and tumour treatment modalities combining radiosensitizing chemical agents with irradiation are under investigation in order to achieve greater tumour local control and reduce the probability of distant failures. The combined treatment modality of radiation and the clinically relevant microtubule-stabilizing compound epothilone B is a promising approach for anticancer therapy. In the present study, we investigated the cytotoxicity of a spread out Bragg peak (SOBP) proton beam, as well as of 6 MV photons, in human glioblastoma (U251 MG) and lung adenocarcinoma (A549) cells pretreated for 24 h, or not, with epothilone B at concentrations of 0.125 and 0.075 nM respectively. Proton irradiation was performed at the middle position of an actively modulated SOBP (12–18 cm depth in water) and cell survival was evaluated by a colony forming assay. For both cell lines, survival curves after proton or photon irradiation alone showed linear quadratic behaviour with proton RBE (relative biological effectiveness), compared with photons at 10% survival, of 1.5 ± 0.2. Treatment of cells with epothilone B at subnanomolar concentration has an anticlonogenic effect. Furthermore, differently from the results found with radiation alone, the survival curves for the combined treatment epothilone B–radiation showed a linear trend and analysis of the interaction of the two cytotoxic agents indicated a slight synergism. These data provide a radiobiological basis for further experiments, as well as clinical studies.

Biosynthesis of Silver Nanoparticles Using Taxus yunnanensis Callus and Their Antibacterial Activity and Cytotoxicity in Human Cancer Cells.

Plant constituents could act as chelating/reducing or capping agents for synthesis of silver nanoparticles (AgNPs). The green synthesis of AgNPs has been considered as an environmental friendly and cost-effective alternative to other fabrication methods. The present work described the biosynthesis of AgNPs using callus extracts from Taxus yunnanensis and evaluated their antibacterial activities in vitro and potential cytotoxicity in cancer cells. Callus extracts were able to reduce silver nitrate at 1 mM in 10 min. Transmission electron microscope (TEM) indicated the synthesized AgNPs were spherical with the size range from 6.4 to 27.2 nm. X-ray diffraction (XRD) confirmed the AgNPs were in the form of nanocrystals. Fourier transform infrared spectroscopy (FTIR) suggested phytochemicals in callus extracts were possible reducing and capping agents. The AgNPs exhibited effective inhibitory activity against all tested human pathogen bacteria and the inhibition against Gram-positive bacteria was stronger than that of Gram-negative bacteria. Furthermore, they exhibited stronger cytotoxic activity against human hepatoma SMMC-7721 cells and induced noticeable apoptosis in SMMC-7721 cells, but showed lower cytotoxic against normal human liver cells (HL-7702). Our results suggested that biosynthesized AgNPs could be an alternative measure in the field of antibacterial and anticancer therapeutics.

The Essential Oil Compositions of Ocimum basilicum from Three Different Regions: Nepal, Tajikistan, and Yemen.

The aerial parts of Ocimum basilicum L. were collected from four different geographical locations, Sindhuli and Biratnagar (Nepal), Chormaghzak village (Tajikistan), and Sana'a (Yemen). The essential oils were obtained by hydrodistillation and analyzed by gas chromatography/mass spectrometry. A cluster analysis of 179 essential oil compositions revealed six major chemotypes: Linalool, eugenol, estragole, methyl eugenol, 1,8-cineole, and geraniol. All four of the basil oils in this study were of the linalool-rich variety. Some of the basil oils were screened for bioactivity including antimicrobial, cytotoxicity in human cancer cells, brine shrimp lethality, nematicidal, larvicidal, insecticidal, and antioxidant. The basil oils in this study were not notably antibacterial, cytotoxic, antioxidant, nor nematicidal, but were active in the brine shrimp lethality test, and did show larvicidal and insecticidal activities.

BIAN N-Heterocyclic Gold Carbene Complexes induced cytotoxicity in human cancer cells via upregulating oxidative stress.

Nanoparticles of gold and silver are offering revolutionary changes in the field of cancer therapy. N-heterocyclic carbene (NHC) metal complexes possess diverse biological activities and are being investigated as potential chemotherapeutic agents. The purpose of this study was to examine the cytotoxicity and possible mechanisms of action of two types of newly synthesized nanofiber composites containing BIAN N-heterocyclic gold carbene complexes in two types of human cancer cells, namely breast cancer (MCF7) and liver cancer (HepG2) cells and also in normal human embryonic kidney cells (HEK 293). Cytotoxicity was assessed by MTT cell viability assay and oxidative stress by checking the total glutathione level. Both compounds affected the cell survival of the tested cell lines at very low concentrations (IC50 values in the micro molar range) as compared to a well-known anti-cancer drug, 5 fluorouracil. A 60-80% depletion in total glutathione level was detected in treated cells. Reduction in total glutathione level is one of the biochemical pathways for the induction of oxidative stress which in turn could be a possible mechanism of action by which these compounds induce cytotoxicity in cancer cell lines. The in vitro toxicity towards cancer cells found here means that these molecules could be potential anticancer candidates.

Rational design of a cytotoxic dinuclear Cu2 complex that binds by molecular recognition at two neighboring phosphates of the DNA backbone.

The mechanism of the cytotoxic function of cisplatin and related anticancer drugs is based on their binding to the nucleobases of DNA. The development of new classes of anticancer drugs requires establishing other binding modes. Therefore, we performed a rational design for complexes that target two neighboring phosphates of the DNA backbone by molecular recognition resulting in a family of dinuclear complexes based on 2,7-disubstituted 1,8-naphthalenediol. This rigid backbone preorganizes the two metal ions for molecular recognition at the distance of two neighboring phosphates in DNA of 6-7 Å. Additionally, bulky chelating pendant arms in the 2,7-position impede nucleobase complexation by steric hindrance. We successfully synthesized the Cu(II)2 complex of the designed family of dinuclear complexes and studied its binding to dsDNA by independent ensemble and single-molecule methods like gel electrophoresis, precipitation, and titration experiments followed by UV-vis spectroscopy, atomic force microscopy (AFM), as well as optical tweezers (OT) and magnetic tweezers (MT) DNA stretching. The observed irreversible binding of our dinuclear Cu(II)2 complex to dsDNA leads to a blocking of DNA synthesis as studied by polymerase chain reactions and cytotoxicity for human cancer cells.

Photoactive Ru(II) complexes with dioxinophenanthroline ligands are potent cytotoxic agents.

Two novel strained ruthenium(II) polypyridyl complexes containing a 2,3-dihydro-1,4-dioxino[2,3-f]-1,10-phenanthroline (dop) ligand selectively ejected a methylated ligand when irradiated with >400 nm light. The best compound exhibited a 1880-fold increase in cytotoxicity in human cancer cells upon light-activation and was 19-fold more potent than the well-known chemotherapeutic, cisplatin.

Thymoquinone Inhibits Autophagy and Induces Cathepsin-Mediated, Caspase-Independent Cell Death in Glioblastoma Cells

Glioblastoma is the most aggressive and common type of malignant brain tumor in humans, with a median survival of 15 months. There is a great need for more therapies for the treatment of glioblastoma. Naturally occurring phytochemicals have received much scientific attention because many exhibit potent tumor killing action. Thymoquinone (TQ) is the bioactive compound of the Nigella sativa seed oil. TQ has anti-oxidant, anti-inflammatory and anti-neoplastic actions with selective cytotoxicity for human cancer cells compared to normal cells. Here, we show that TQ selectively inhibits the clonogenicity of glioblastoma cells as compared to normal human astrocytes. Also, glioblastoma cell proliferation could be impaired by chloroquine, an autophagy inhibitor, suggesting that glioblastoma cells may be dependent on the autophagic pathway for survival. Exposure to TQ caused an increase in the recruitment and accumulation of the microtubule-associated protein light chain 3-II (LC3-II). TQ also caused an accumulation of the LC3-associated protein p62, confirming the inhibition of autophagy. Furthermore, the levels of Beclin-1 protein expression were unchanged, indicating that TQ interferes with a later stage of autophagy. Finally, treatment with TQ induces lysosome membrane permeabilization, as determined by a specific loss of red acridine orange staining. Lysosome membrane permeabilization resulted in a leakage of cathepsin B into the cytosol, which mediates caspase-independent cell death that can be prevented by pre-treatment with a cathepsin B inhibitor. TQ induced apoptosis, as determined by an increase in PI and Annexin V positive cells. However, apoptosis appears to be caspase-independent due to failure of the caspase inhibitor z-VAD-FMK to prevent cell death and absence of the typical apoptosis related signature DNA fragmentation. Inhibition of autophagy is an exciting and emerging strategy in cancer therapy. In this vein, our results describe a novel mechanism of action for TQ as an autophagy inhibitor selectively targeting glioblastoma cells.

Abstract 2252: Mechanism of thymoquinone-induced cell death in glioblastoma multiforme.

Abstract Glioblastoma (GBM) is the most aggressive and common type of brain tumor in humans. Surgical resection followed by radiation and chemotherapy is the current standard treatment; however, due to the upregulation of several survival pathways, tumor recurrence is quite common with a median survival of 12 to 15 months. Therefore, there is an urgent need for more effective therapeutic strategies for the treatment of glioblastoma. Naturally occurring phytochemicals have steadily received much scientific attention, owing to the fact that many of these compounds have potent action against tumors. Thymoquinone (TQ) is the bioactive compound of the volatile oil extracted from the black seed, Nigella sativa. TQ has shown anti-oxidant, anti-inflammatory and anti-neoplastic actions with a selective cytotoxicity for human cancer cells compared to several normal cells. Here, we show that TQ can dose-dependently inhibit colony formation in three distinct glioblastoma cell lines, with the highly tumorigenic Gli36ΔEGFR displaying the greatest sensitivity to the anti-proliferative effects of TQ. Moreover, normal human astrocytes are far less sensitive to TQ-induced cell kill. The absence of both DNA fragmentation and PARP cleavage in U87 and Gli36ΔEGFR cells suggests that TQ does not activate apoptosis. We show that TQ does not change the levels of Beclin-1 expression, but does cause accumulation of LC3-II and p62 protein levels. This suggests that TQ blocks the late stages of autophagy. TQ-induced cell death can be partially rescued by co-treatment with a lysosomal cathepsin hydrolase inhibitor III. We also show that TQ induces persistent γ-H2AX activation and causes G2/M cell cycle arrest in GBM cells to a degree that correlates with the cells’ relative clonogenic sensitivity. Moreover, co-treatment with TQ and N-acetyl cysteine, a simple thiol nucleophile and antioxidant, prevented cell death, DNA double strand breaks, and cell cycle arrest. Citation Format: Ira O. Racoma, Robert M. Snapka, Altaf A. Wani. Mechanism of thymoquinone-induced cell death in glioblastoma multiforme. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2252. doi:10.1158/1538-7445.AM2013-2252

Zinc protoporphyrin suppresses cancer cell viability through a heme oxygenase-1-independent mechanism: The involvement of the Wnt/β-catenin signaling pathway

Zinc protoporphyrin (ZnPP), a known inhibitor of heme oxygenase-1 (HO-1), has been reported to have anticancer activity in both in vitro and in vivo model systems. While the mechanisms of ZnPP's anticancer activity remain to be elucidated, it is generally believed that ZnPP suppresses tumor growth through inhibition of HO-1 activity. We examined this hypothesis by altering cellular levels of HO-1 in human ovarian (A2780) and prostate cancer (DU145) cells and found that ZnPP inhibits cancer cell viability through an HO-1-independent mechanism. Neither over-expression nor knockdown of HO-1 significantly alters ZnPP's cytotoxicity in human cancer cells, indicating that HO-1 does not mediate ZnPP's inhibitory effect on cancer cell growth. Consistent with these observations, tin protoporphyrin (SnPP), a well-established HO-1 inhibitor, was found to be much less cytotoxic than ZnPP, and docosahexaenoic acid (DHA), an HO-1 inducer, enhanced ZnPP's cytotoxicity. In an effort to define the mechanisms of ZnPP-induced cytotoxicity, we found that ZnPP but not SnPP, diminished β-catenin expression through proteasome degradation and potently suppressed β-catenin-mediated signaling in our model systems. Thus, ZnPP-induced cytotoxicity is independent of HO-1 expression in cancer cells and the Wnt/β-catenin pathway is potentially involved in ZnPP's anticancer activity.

Structure-related cytotoxic activity of derivatives from kulokekahilide-2, a cyclodepsipeptide in Hawaiian marine mollusk

Kulokekahilide-2, a 26-membered cyclodepsipeptide, was isolated from Hawaiian marine mollusk and possessed potent cytotoxicity in mammalian tumor cells. In the present study, we synthesized kulokekahilide-2 and its derivatives and examined the structure–activity relationships of these peptides in human cancer cells (A549, K562, and MCF7 cells). This study demonstrated that the cyclization of depsipeptide and the chirality of the 21 position in Ala in kulokekahilide-2 were important for its cytotoxic property and that addition of halogen at the para position of phenyl group in the 24-d-MePhe in kulokekahilide-2 as well as some derivatives remarkably increased their cytotoxicity in human cancer cells. These results suggest that the modifications of 24-d-MePhe in kulokekahilide-2, preserving its cyclization and the chirality at the 21-position, are promising strategy for exploring new derivative of kulokekahilide-2 as anti-tumor drug.

Antioxidant Activity, Total Phenolics and Taxol Contents Response of Hazel (Corylus avellana L.) Cells to Benzoic Acid and Cinnamic Acid

Hazel (Corylus avellana L.) plant has been recently introduced as a plant with the ability to produce Taxol. In the present research effects of different concentrations of benzoic acid and cinnamic acid on the phenolic compounds, Taxol content, and antioxidant activity of extracts of suspension-cultured hazel cells were investigated. The cells were treated with different concentrations of benzoic acid (0, 0.5, and 1 mM) and cinnamic acid (0, 0.15, 0.3 and 0.6 mM) on day 7 of subculture and were harvested on day 14. Benzoic acid in higher concentrations increased Taxol (4 fold of the control) and antioxidant activity of the cell extract. Cinnamic acid supply did not bring remarkable increase in Taxol content but increased phenolic contents and antioxidant activity of hazel cells extract. Interestingly, the extract of hazel cells showed more cytotoxicity for human cancer cells than pure Taxol. Further investigations may suggest the extract of cinnamic- and benzoic acid- fed hazel cells for treatment of cancer cells.

Abstract 1983: Thymoquinone induces cell killing in glioblastoma cells through generation of DNA damage and cell cycle arrest

Abstract Glioblastoma (GBM) is the most aggressive and common type of brain tumor in humans. Surgical resection followed by radiation and chemotherapy is the current standard treatment; however, due to the upregulation of several survival pathways, tumor recurrence is quite common with a median survival of 12 to 15 months. Therefore, there is an urgent need for more effective therapeutic strategies for the treatment of glioblastoma. Naturally occurring phytochemicals have steadily received much scientific attention, owing to the fact that many of these compounds have potent action against tumors. Thymoquinone (TQ) is the bioactive compound of the volatile oil extracted from the black seed, Nigella sativa. TQ has shown anti-oxidant, anti-inflammatory and anti-neoplastic actions with a selective cytotoxicity for human cancer cells compared to several normal cells. Here, we show that TQ is able to dose-dependently inhibit colony formation in three distinct glioblastoma cell lines (T98, U87 and Gli36), with the highly tumorigenic Gli36 being the most sensitive to the anti-proliferative effects of TQ. We also show that TQ induces persistent γ-H2AX activation, a marker of DNA double strand breaks, in a time- and dose-dependent manner. TQ also causes G2/M cell cycle arrest in GBM cells to a degree that correlates with the cells’ relative clonogenic sensitivity. Moreover, co-treatment with TQ and N-acetyl cysteine, a simple thiol nucleophile and antioxidant, prevented cell death, DNA double strand breaks, and cell cycle arrest. Taken together, our findings demonstrate that TQ is a potent inhibitor of GBM cell proliferation and growth, and that this effect may be mediated by generation of reactive oxygen species. 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 1983. doi:1538-7445.AM2012-1983

In vitro growth inhibition of human cancer cells by novel honokiol analogs

Honokiol possesses many pharmacological activities including anti-cancer properties. Here in, we designed and synthesized honokiol analogs that block major honokiol metabolic pathway which may enhance their effectiveness. We studied their cytotoxicity in human cancer cells and evaluated possible mechanism of cell cycle arrest. Two analogs, namely 2 and 4, showed much higher growth inhibitory activity in A549 human lung cancer cells and significant increase of cell population in the G0–G1 phase. Further elucidation of the inhibition mechanism on cell cycle showed that analogs 2 and 4 inhibit both CDK1 and cyclin B1 protien levels in A549 cells.