Extracts from Calendula officinalis offer in vitro protection against H2 O2 induced oxidative stress cell killing of human skin cells.

The in vitro safety and antioxidant potential of Calendula officinalis flower head extracts was investigated. The effect of different concentrations (0.125, 0.5, 1.0, 2.0 and 5.0% (v/v)) of Calendula extracts on human skin cells HaCaT in vitro was explored. Doses of 1.0% (v/v) (0.88 mg dry weight/mL) or less showed no toxicity. Cells were also exposed to the Calendula extracts for either 4, 24 or 48 h before being exposed to an oxidative insult (hydrogen peroxide H2 O2 ) for 1 h. Using the MTT cytotoxicity assay, it was observed that two independent extracts of C. officinalis gave time-dependent and concentration-dependent H2 O2 protection against induced oxidative stress in vitro using human skin cells. Pre-incubation with the Calendula extracts for 24 and 48 h increased survival relative to the population without extract by 20% and 40% respectively following oxidative challenge. The antioxidant potential of the Calendula extracts was confirmed using a complimentary chemical technique, the DPPH(●) assay. Calendula extracts exhibited free radical scavenging abilities. This study demonstrates that Calendula flower extracts contain bioactive and free radical scavenging compounds that significantly protect against oxidative stress in a human skin cell culture model.

Venom present in sea anemone (Heteractis magnifica) induces apoptosis in non-small-cell lung cancer A549 cells through activation of mitochondria-mediated pathway.

Lung cancer is a major cause of cancer deaths throughout the world and the complexity of apoptosis resistance in lung cancer is apparent. Venom from Heteractis magnifica caused dose-dependent decreases in survival of the human non-small-cell lung cancer cell line, as determined by the MTT and Crystal Violet assays. The H. magnifica venom induced cell cycle arrest and induced apoptosis of A549 cells, as confirmed by annexin V/propidium iodide staining. The venom-induced apoptosis in A549 cells was characterized by cleavage of caspase-3 and a reduction in the mitochondrial membrane potential. Interestingly, crude extracts from H. magnifica had less effect on the survival of non-cancer cell lines. In the non-cancer cells, the mechanism via which cell death occurred was through necrosis not apoptosis. These findings are important for future work using H. magnifica venom for pharmaceutical development to treat human lung cancer.

The effect of sea anemone (H. magnifica) venom on two human breast cancer lines: death by apoptosis.

Venom from the sea anemone, Heteractis magnifica, has multiple biological effects including, cytotoxic, cytolytic and hemolytic activities. In this study, cytotoxicity induced by H. magnifica venom was investigated using the crystal violet assay on human breast cancer T47D and MCF7 cell lines and normal human breast 184B5 cell line. Apoptosis was also assayed via Annexin V-flourescein isothiocyanate and propidium iodide (PI) staining followed by flow cytometric analysis. Cell cycle progression and mitochondria membrane potential were studied via flow cytometry following PI and JC-1 staining respectively. H. magnifica venom induced significant reductions in viable cell numbers and increases in apoptosis in T47D and MCF7 in dose-dependent manners. A significant apoptosis-related increase in the sub G1 peak of the cell cycle in both breast cancer cell lines was also observed. Moreover, treatment by venom cleaved caspase-8, caspase-9, and activated caspase-3. Overall, H. magnifica venom was highly cytotoxic to T47D and MCF7 human breast cancer cells, and the phenomenon could be the killing phenomenon via the death receptor-mediated and the mitochondria-mediated apoptotic pathways. Consequently, H. magnifica venom has potential for the development of a breast cancer therapeutic.

Altered mRNA expression related to the apoptotic effect of three xanthones on human melanoma SK-MEL-28 cell line.

We previously demonstrated that α-mangostin, γ-mangostin, and 8-deoxygartanin have significant cytotoxic effects on human melanoma SK-MEL-28 cell line. The current study revealed the underlying mechanisms. α-Mangostin (7.5 µg/mL) activated caspase activity, with a 3-fold and 4-fold increased caspase 8 and 9 activity, respectively. The molecular mechanisms were investigated by qRT-PCR for mRNA related to cell cycle arrest in G1 phase (p21(WAF1) and cyclin D1), apoptosis (cytochrome C, Bcl-2, and Bax), and survival pathways (Akt1, NFκB, and IκBα). α-Mangostin significantly upregulated mRNA expression of cytochrome C and p21(WAF1) and downregulated that of cyclin D1, Akt1, and NFκB. γ-Mangostin significantly downregulated mRNA expression of Akt1 and NFκB and upregulated p21(WAF1) and IκBα. 8-Deoxygartanin significantly upregulated the mRNA expression of p21(WAF1) and downregulated that of cyclin D1 and NFκB. The three xanthones significantly inhibited the mRNA expression of the BRAF V600E mutation. Moreover, α-mangostin and γ-mangostin significantly downregulated Akt phosphorylation at Ser473. In conclusion, the three xanthones induced an inhibitory effect on SK-MEL-28 cells by modulating the molecular targets involved in the apoptotic pathways.

In vitro adverse effects of iron ore dusts on human lymphoblastoid cells in culture.

The aim of this study was to investigate the adverse effects produced by four types of iron (Fe) ore dust using cultured human cells. Genotoxicity and cytotoxicity induced by Fe ore dusts were determined by assays including cytokinesis block micronucleus (CBMN), population growth, and methyl tetrazolium (MTT). Four iron ore dusts were tested, namely, 1002 Limonite & Goethite (1002), HG2 hematite (HG2), HG1 Soutlem Pit (HG1), and HG4. WIL2 -NS cells were incubated for 10 h with extracts from a range of concentrations (0, 75, or 150 µg/ml) of Fe ore dust. Significant decreases in percent cell viability were seen at 150 µg/ml HG2 and 1002 as measured by MTT, with viability that decreased to 75 and 73%, respectively, compared to untreated controls. The cell population regrew to a different extent after Fe ore dust was removed, except for HG1, where population remained declined. An approximately twofold significant increase in the frequency of micronucleated binucleated cells (MNBNC) was seen with 1002, HG2, and HG1 at 150 µg/ml. A significant rise in apoptosis induction was observed at 150 µg/ml HG1. Data indicate that Fe ore dusts at 150 µg/ml produced cytotoxicity and genotoxicity.

Significant anti-invasive activities of α-mangostin from the mangosteen pericarp on two human skin cancer cell lines.

AIM: This study aimed at investigating the anti-invasive activities of α-mangostin on human melanoma SK-MEL-28 and squamous cell carcinoma A-431 cell lines. MATERIALS AND METHODS: Cytotoxicity was tested by the crystal violet assay; anti-invasive activity was detected by the wound healing, cell-matrix adhesion, and boyden chamber assays; and gene regulatory effects by qRT-PCR. Treatments were at non-toxic concentrations (0-1.25 µg/ml for A-431 cells and 0-2.5 µg/ml for SK-MEL-28 cells). RESULTS: α-Mangostin inhibited motility, adhesion, migration and invasion. Invasive ability was reduced to 4% and 20% following α-mangostin treatment compared with untreated A-431 and SK-MEL-28 cells, respectively. Inhibition of gene expression of MMP-2, MMP-9, NF-κB, and Akt1 was involved in the anti-invasive activities on A-431 cells. Inhibition of MMP-2, NF-κB and IκBα was involved for SK-MEL-28 cells. CONCLUSION: α-Mangostin suppressed the metastatic processes of SK-MEL-28 and A-431 cell lines by differentially regulating metastasis-related genes, showing potential as an anti-metastatic agent.

Anti-skin cancer properties of phenolic-rich extract from the pericarp of mangosteen (Garcinia mangostana Linn.).

Skin cancers are often resistant to conventional chemotherapy. This study examined the anti-skin cancer properties of crude ethanol extract of mangosteen pericarp (MPEE) on human squamous cell carcinoma A-431 and melanoma SK-MEL-28 lines. Significant dose-dependent reduction in% viability was observed for these cell lines, with less effect on human normal skin fibroblast CCD-1064Sk and keratinocyte HaCaT cell lines. Cell distribution in G(1) phase (93%) significantly increased after 10 µg/ml of MPEE versus untreated SK-MEL-28 cells (78%), which was associated with enhanced p21(WAF1) mRNA levels. In A-431 cells, 10 µg/ml MPEE significantly increased the sub G(1) peak (15%) with concomitant decrease in G(1) phase over untreated cells (2%). In A-431 cells, 10 µg/ml MPEE induced an 18% increase in early apoptosis versus untreated cells (2%). This was via caspase activation (15-, 3- and 4-fold increased caspse-3/7, 8, and 9 activities), and disruption of mitochondrial pathways (6-fold decreased mitochondrial membrane potential versus untreated cells). Real-time PCR revealed increased Bax/Bcl-2 ratio and cytochrome c release, and decreased Akt1. Apoptosis was significantly increased after MPEE treatment of SK-MEL-28 cells. Hence, MPEE showed strong anti-skin cancer effect on these two skin cancer cell lines, with potential as an anti-skin cancer agent.

Cytotoxic effect of xanthones from pericarp of the tropical fruit mangosteen (Garcinia mangostana Linn.) on human melanoma cells.

Mangosteen (Garcinia mangostana Linn.) is a tropical tree from South East Asia and its fruit pericarp is a well-known traditional medicine. In this study, the cytotoxic effect of three xanthone compounds (α-mangostin, γ-mangostin, and 8-deoxygartanin) from mangosteen pericarp was investigated using the human melanoma SK-MEL-28 cell line. Significant dose-dependent reduction in % cell viability was induced. γ-Mangostin and 8-deoxygartanine at 5 µg/ml increased the cell cycle arrest in G(1) phase (90% and 92%) compared with untreated cells (78%). All compounds induced apoptosis, of the highest being α-mangostin at 7.5 µg/ml that induced 59.6% early apoptosis, compared to 1.7% in untreated cells. The apoptotic effect of α-mangostin was via caspase activation and disruption of mitochondrial membrane pathways as evidenced by 25-fold increased caspase-3 activity and 9-fold decreased mitochondrial membrane potential when compared to untreated cells. In conclusion, these xanthones, especially α-mangostin, are potential candidates as anti-melanoma agents.

Selective growth inhibition of human leukemia and human lymphoblastoid cells by resveratrol via cell cycle arrest and apoptosis induction.

There is great interest in the potential chemopreventive activity of resveratrol against human cancers. However, there are conflicting results on its growth inhibitory effect on normal cells. This project examined the differential effect of resveratrol at physiologically relevant concentrations on nonmalignant (WIL2-NS) and malignant (HL-60) cell lines and compared the underlying mechanisms via cell cycle modulation, apoptosis induction, and genotoxicity potential. Twenty-four hours of exposure to resveratrol was toxic to WIL2-NS and HL-60 cells in a dose-dependent manner. WIL2-NS cells regrew 5 times more than HL-60 cells by 120 h after the removal of 100 microM resveratrol (p < 0.05). Furthermore, significant alterations in cell cycle kinetics were induced by resveratrol in HL-60 cells, but were to a lesser extent for WIL2-NS cells. The proportion of apoptosis was also 3 times higher in HL-60 cells as compared to WIL2-NS cells for 100 microM resveratrol (p < 0.05). In conclusion, resveratrol preferentially inhibited the growth of HL-60 cells via cell cycle modulation and apoptosis induction and subsequently directed the cells to irreversible cell death, whereas the effect on WIL2-NS cells was largely reversible.

Cytotoxicity and genotoxicity of ultrafine crystalline SiO2 particulate in cultured human lymphoblastoid cells.

Respirable crystalline silica has been classified as a human lung carcinogen. Ultrafine (diameter < 100 nm) silica particles may be important in carcinogenesis, although the mechanisms remain unclear. In the present study, WIL2-NS cells were incubated for 6, 24, and 48 hr with 0, 30, 60, and 120 microg/ml ultrafine crystalline SiO(2) (UF-SiO(2)). The cytotoxic and genotoxic effects caused by UF-SiO(2) in cultured human cells were investigated via a set of bioassays. Significant dose- dependent decreases in percent cell viability were seen with increasing dose of UF-SiO(2) in the methyl tetrazolium assay. Significant decreases were seen at 120 microg/ml (58, 38, and 57% for 6, 24, and 48-hr exposure, respectively). During 4 days growth in the flasks, there was a slight recovery observed after washing off UF-SiO(2) as measured by the population growth assay. Significant dose-dependent reduction in the cytokinesis block proliferation index was observed by the cytokinesis block micronucleus assay. Treatment with 120 microg/ml UF-SiO(2) for 24 hr produced a fourfold increase in the frequency of micronucleated binucleated cells (MNBNC). The increase in MNBNC was dose-dependent. The lowest dose that gave a statistically significant increase in MNBNC was 30 microg/ml (24-hr treatment), which had cytotoxicity of less than 10%. There was no significant difference in DNA strand breakage as measured by the Comet assay. A significant increase in induced mutant frequency was found at 120 microg/ml as detected by the hypoxanthine guanine phosphoribosyltransferase mutation assay. The results indicate that UF-SiO(2) is cytotoxic and genotoxic in cultured human cells.

Cyto- and genotoxicity of ultrafine TiO2 particles in cultured human lymphoblastoid cells.

Titanium dioxide is frequently used in the production of paints, paper, plastics, welding rod-coating material, and cosmetics, because of its low toxicity. However, recent studies have shown that nano-sized or ultrafine TiO(2) (UF-TiO(2)) (<100 nm in diameter) can generate pulmonary fibrosis and lung tumor in rats. Cytotoxicity induced by UF-TiO(2) in rat lung alveolar macrophages was also observed. This generates great concern about the possible adverse effects of UF-TiO(2) for humans. The cytotoxicity and genotoxicity of UF-TiO(2) were investigated using the methyl tetrazolium cytotoxicity (MTT) assay, the population growth assay, the apoptosis assay by flow cytometry, the cytokinesis block micronucleus (CBMN) assay, the comet assay, and the hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene mutation assay. WIL2-NS cells were incubated for 6, 24 and 48 h with 0, 26, 65 and 130 microg/ml UF-TiO(2). Significant decreases in viability were seen in the MTT assay at higher doses; for example, 61, 7 and 2% relative viability at 130 microg/ml for 6, 24 and 48-h exposure (P<0.01). A dose-dependent relationship was observed, while a time-dependent relationship was seen only at the highest dose (130 microg/ml) after exposure for 24 and 48 h. Treatment with 130 microg/ml UF-TiO(2) induced approximately 2.5-fold increases in the frequency of micronucleated binucleated cells (P<0.01). In addition, a significant reduction in the cytokinesis block proliferation index was observed by the CBMN assay (P<0.05). In the comet assay, treatment with 65 microg/ml UF-TiO(2) induced approximately 5-fold increases in olive tail moment (P<0.05). In the HPRT mutation assay, treatment with 130 microg/ml UF-TiO(2) induced approximately 2.5-fold increases in the mutation frequency (P<0.05). The results of this study indicate that UF-TiO(2) can cause genotoxicity and cytotoxicity in cultured human cells.

Ultrafine Quartz-Induced Damage in Human Lymphoblastoid Cells in vitro Using Three Genetic Damage End-Points.

ABSTRACT Respirable quartz is a potential human lung carcinogen. The mechanisms involved in this carcinogenesis, however, remain unclear, especially for the ultrafine particles (diameter <100 nm). The aim of the present study was to investigate the effects caused by ultrafine quartz (UF-quartz) in a human cell culture model. Genotoxicity and cytotoxicity induced by UF-quartz were investigated through the cytokinesis block micronucleus assay (CBMN), the Comet assay, the HPRT assay, the population growth assay, and the 3-(4, 5-dimethythiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. WIL2-NS cells were incubated for 10h with 0, 60, and 120 mug/mL UF-quartz. Significant decreases in percent of cell survival in the MTT assay were seen at higher doses, for example, 83%, and 64% relative survival at 60 mug/mL and 120 mug/mL, respectively. Only slight population regrowth was observed, with the population sizes recovering slightly by day 4 after quartz particles were removed. A significant increase in the frequency of micronucleated binucleated cells (MNed BNCs) was seen with 120 mug/mL quartz, from approximately 5 in 1000 BNCs in controls to 12 in 1000 BNCs. A significant reduction in the nuclear division index was observed by the CBMN assay, indicating inhibition of cell division by high-dose UF-quartz. A dose-dependent increase in induced HPRT-gene locus mutant frequency with increasing dose of UF-quartz was observed by the HPRT assay. No significant difference was found in DNA strand breakage as detected by the Comet assay. Collective findings suggest that UF-quartz can cause cytotoxicity and genotoxicity to human lymphoblasts in this model system.

Modification of MTT assay conditions to examine the cytotoxic effects of amitraz on the human lymphoblastoid cell line, WIL2NS.

Reported parameters of the MTT assay vary widely, and reflect a need to optimise the assay for different cell types. The MTT assay conditions for the human B-lymphocyte-derived cell line WIL2NS were optimised for MTT incubation and formazan development. The optimised MTT assay was validated by examining the effects of the acaride amitraz on WIL2NS. In pH-buffered media in the absence of cells, MTT formed formazan spontaneously, and absorbance was proportional to both the initial concentration of MTT and the time of incubation at 37 degrees C. One milligram per millilitre MTT was toxic to WIL2NS cells, but the accuracy of the standard curve was reduced when only 0.2 mg/ml MTT was used. Twenty percent SDS in 0.2 M HCl was preferable to DMSO as a solvent for formazan. Exposure to 0.035% amitraz resulted in a significant reduction in WIL2NS cell numbers after only 2 h of exposure. It was concluded that 0.035% of amitraz has the potential to adversely affect lymphocytes in the systemic blood system in humans, and that an optimised MTT assay was obtained by incubating WIL2NS cells with 0.45 mg/ml MTT for 17 h, followed by addition of acidified SDS for 1 h.

A recombinant model for assessing the role of GSTM1 in styrene-7,8-oxide toxicity and mutagenicity.

Styrene-7,8-oxide (SO) is a highly reactive epoxide able to undergo reactions with endogenous nucleophiles, such as DNA. SO is inactivated by glutathione-S-transferase M1 (GSTM1). This detoxification enzyme is absent in approximately one-half of Caucasian (49%) populations. A GSTM1 recombinant human lymphoblastoid cell line (FB7) was generated from a GSTM1 negative parental cell line (WIL2NS). GSTM1 status was determined using RT-PCR and immunochemistry. Cells were challenged with a range of SO doses and subsequent toxicity (population growth in flasks) and genotoxicity (mutations at the HPRT locus) were monitored. FB7 (GSTM1 positive) exhibited greater cell survival after SO exposure relative to the GSTM1 negative parental line. The IC50 following a 1 h exposure to SO was 0.5 mM for WIL2NS, compared to greater than 2.5 mM for FB7. The extrapolated IC50 for FB7 was 5.5 mM. Significantly fewer mutant cells were induced by SO for FB7 than for WIL2NS at equivalent doses of SO. These findings suggest that the sensitivity of cells to styrene-7,8-oxide is influenced by GSTM1 status and that a recombinant GSTM1 positive cell line can efficiently detoxify styrene-7,8-oxide.