Inhibition of autophagy promotes caspase-mediated apoptosis by tunicamycin in HepG2 cells

Tunicamycin (TM) causes accumulation of unfolded protein in endoplasmic reticulum (ER) lumen and introduces from elsewhere ER stress. This study was to assess the apoptosis and autophagy effect induced by TM on HepG2 cells and the role of autophagy in the system. The viability of HepG2 cells was significantly inhibited by TM in a dose-dependent manner detected by MTT assay. Then, the apoptotic morphology change, increasing apoptotic cell rate suggested that apoptosis was induced by TM in a time- and dose-dependent manner. To further determine the involvement of caspase-dependent pathway in TM-induced apoptosis, we discover that the activity of caspase-3/7, 8, 9 and cleavage of PARP markedly increased after TM treatment and the apoptosis was effectively attenuated by using caspase-9 and pan caspase inhibitor. Moreover, provided the rising stained acidic vacuoles and an increased level of LC3II and activation of Beclin1, we concluded that autophagy could be triggered by TM in a time- and dose-dependent manner. In addition, the inhibition of autophagy efficiently promoted TM-induced cell death identified by MTT assay. Meanwhile, the apoptotic cell rate and caspase-3 activation increased significantly after autophagy blockage. In conclusion, we found that TM initiated apoptosis and autophagy both in a time- and dose-dependent manner in HepG2 cells; and inhibition of autophagy may promote TM-induced cell death through enhancing apoptosis.

Biotransformation of 20(R)-panaxadiol by the fungus Rhizopus chinensis

Microbial transformation of 20(R)-panaxadiol by the fungus Rhizopus chinensis CICC 3043 yielded seven metabolites. Their structures were elucidated on the basis of extensive spectroscopic analyses. R. chinensis could catalyze hydroxylation and further dehydrogenation at C-24 of 20(R)-panaxadiol, as well as hydroxylation at C-7, C-15, C-16, and C-29. Three of these compounds at 10μM could moderately inhibit growth of HepG2 human hepatocellular carcinoma cells with an inhibition rate of about 40%. Three compounds (also at 10μM) showed approximately 30% inhibition on NF-κB transcriptional activity in SW480 human colon carcinoma cells stably transfected with NF-κB luciferase reporter and induced by LPS.

New cytotoxic isoprenoid derivatives from the Red Sea soft coral Sarcophyton glaucum

Chemical investigation of the soft coral Sarcophyton glaucum collected from the Red Sea led to isolation of 11 isoprenoidal metabolites (1-11). A new sesquiterpenoid, 6-oxo-germacra-4(15),8,11-triene (1), a new natural cembranoid, sarcophinediol, along with two known sesquiterpenoids (2 and 3) and seven known cembranoids (5-11) was obtained. The structures of the compounds were established based on their NMR, MS, IR and UV spectral data. All compounds were evaluated for their cytotoxicity employing three cancer cell lines (HepG2, MCF-7 and HCT116). Compounds 4 and 6 showed significant cytotoxicity towards HepG2 with IC50 values of 18.8 ± 0.07 and 19.9 ± 0.02 μM; respectively. Compounds 5-7 exhibited potent cytotoxicity against MCF-7 cells with IC50 values of 9.9 ± 0.03, 2.4 ± 0.04 and 3.2 ± 0.02 μM, respectively. Compounds 1, 4 and 5 showed significant activities towards HCT116 cells with IC50 values of 29.4 ± 0.03, 19.4 ± 0.02 and 25.8 ± 0.03 μM, respectively.

De novo LINE-1 retrotransposition in HepG2 cells preferentially targets gene poor regions of chromosome 13

Long interspersed nuclear elements (Line-1 or L1s) account for ~17% of the human genome. While the majority of human L1s are inactive, ~80-100 elements remain retrotransposition competent and mobilize through RNA intermediates to different locations within the genome. De novo insertions of L1s account for polymorphic variation of the human genome and disruption of target loci at their new location. In the present study, fluorescence in situ hybridization and DNA sequencing were used to characterize retrotransposition profiles of L1(RP) in cultured human HepG2 cells. While expression of synthetic L1(RP) was associated with full-length and truncated insertions throughout the entire genome, a strong preference for gene-poor regions, such as those found in chromosome 13 was observed for full-length insertions. These findings shed light into L1 targeting mechanisms within the human genome and question the putative randomness of L1 retrotransposition.

Soil quality in the Lomellina area using in vitro models and ecotoxicological assays

Soil quality is traditionally evaluated by chemical characterization to determine levels of pollutants. Biological tools are now employed for soil monitoring since they can take account of the global biological effects induced by all xenobiotics. A combined monitoring of soils based on chemical analyses, human-related in vitro models and ecotoxicological assay was applied in the Lomellina, a semirural area of northern Italy. Chemical characterization indicated overall good quality of the soils, with low levels of toxic and carcinogenic pollutants such as heavy metals, PAHs, PCDD/Fs and PCBs. HepG2 cells were used as a model for the human liver and BALB/c 3T3 cells to evaluate carcinogenic potential. Cells were treated with soil extractable organic matter (EOM) and the MTS assay, DNA release and morphological transformation were selected as endpoints for toxicity and carcinogenicity. Soil EOMs induced dose-dependent inhibition of cell growth at low doses and cytotoxicity only at doses of 500 and 1000 mg soil equivalents/ml. Potential issues for human health can be hypothesized after ingestion of soil samples from some sites. No statistically significant inductions of foci were recorded after exposure to EOMs, indicating that the levels of the soil-extracted organic pollutants were too low to induce carcinogenesis in our experimental conditions. An acute phytotoxicity test and studies on Caenorhabditis elegans were used as ecotoxicological assays for plants and small invertebrates. No significant alerts for ecotoxicity were found. In this proposed case study, HepG2 cells detected differences in the toxicity of soil EOMs, indicating that this cell line could be appropriate to assess the potential harm caused by the ingestion of contaminated soil. Additional information on the carcinogenic potential of mixtures was provided by the cell transformation assay, strengthening the combined approach.

Resveratrol inhibits alcohol-induced apoptosis via MEK/ERK-SIRT1 signaling in human HepG2 cells

AIM: To investigate the effects of resveratrol on alcohol induced apoptosis of HepG2 cells and to explore the possible mechanisms involved.

METHODS: HepG2 cells were pretreated with resveratrol for 24 h before treatment with alcohol to induce apoptosis. MTT assay was then performed to detect cell cytotoxicity and viability. Inverted fluorescence microscopy was used to detect cell morphologic changes after AO/PI staining. ELISA was performed to detect the presence of intracellular superoxide anion and oxygen radical antioxidant capacity levels. RT-PCR was performed to detect the mRNA expression of Caspase3, mitogen-activated protein kinase kinase (MEK), extracellular signal-regulated kinase (ERK) and silent mating type information regulation 2 homolog (SIRT1).

RESULTS: In comparison with control cells (non-treated with resveratrol), resveratrol at concentrations between 25-100 μmol/L exerted an antagonistic effect against cytotoxicity of 300 mmol/L alcohol to HepG2 cells. AO/PI apoptosis assay showed alcohol-treated cells contained many orange apoptotic cells, but resveratrol treated cells had less orange cells. Different concentrations of resveratrol could decrease the activity of activated Caspase3 in alcohol-treated cells by 2.12, 1.46, 0.90 and 0.75 times. Intracellular superoxide anion concentrations in cells treated with 100, 50 or 25 μmol/L resveratrol were obviously lower than those in alcohol-treated cells. However, the total oxygen radical antioxidant capacity was significantly higher in cells pre-treated with 100, 50, or 25 μmol/L resveratrol compared with alcohol-treated cells (65.74 ± 1.64, 68.14 ± 6.06, 70.81 ± 6.35 vs 45.26 ± 2.75). In addition, resveratrol increased the expression of SIRT1 and ERK mRNAs and decreased the expression of Caspase3 mRNA.

CONCLUSION: Alcohol induces oxidative stress related apoptosis of HepG2 cells, and resveratrol exerts anti-apoptosis effects by regulating the expression of genes involved in the MEK/ERK-SIRT1 pathway.

Mulberry leaf phenolics ameliorate hyperglycemia-induced oxidative stress and stabilize mitochondrial membrane potential in HepG2 cells

To investigate the effect of phenolics in mulberry leaves (mulberry leaf phenolics; MLP) on hyperglycemia-induced oxidative stress and mitochondrial membrane potential (ΔΨm) in HepG2 cells; we treated HepG2 with glucose [5.5 (N-Glc) or 50 mmol/L (Hi-Glc)] with or without MLP at 10 or 100 µmol/L gallic acid equivalents and assessed level of reactive oxidant species (ROS), ΔΨm, malondialdehyde (MDA) and nuclear factor-kappaB (NF-κB) activation. Hi-Glc-induced oxidative damage was demonstrated by a series of increase in superoxides (560%, 0.5 h), MDA (400%, 24 h), NF-κB activation (474%, 4 h) and a wild fluctuation of ΔΨm relative to the control cells (p ≤ 0.05). MLP treatments ameliorate Hi-Glc-induced negative effects by a 40% reduction in ROS production, 34-44% reduction in MDA production, over 35% inhibition of NF-κB activation, as well as exert protective effect on HepG2 cells from change in ΔΨm. Our data show that MLP in vitro can protect hepatoctyes from hyperglycemia-induced oxidative damages.

Inhibition of Aurora-B suppresses HepG2 cell invasion and migration via the PI3K/Akt/NF-κB signaling pathway in vitro

In the present study, the effect of Aurora-B inhibition on HepG2 cell invasion and migration in vitro was investigated. A recombinant plasmid targeting the Aurora-B gene (MiR-Aurora-B) was used to inhibit Aurora-B expression in HepG2 cells. Cell migration and invasion were investigated using Transwell migration and invasion assays. The results demonstrated that cell invasion and migration were suppressed by inhibiting Aurora-B. In addition, the effect of Aurora-B inhibition on the activity of the phosphoinositide 3-kinase (PI3K)/Akt/nuclear factor (NF)-κB signaling pathway was investigated by analyzing the protein expression levels of phosphorylated (p)-Akt, Akt, NF-κB p65, matrix metalloproteinase (MMP)-2 and MMP-9 using western blot analysis. The results demonstrated that the protein expression levels of p-Akt, NF-κB p65, MMP-2 and MMP-9 were reduced significantly by inhibiting Aurora-B. Therefore, inhibition of Aurora-B was shown to suppress hepatocellular carcinoma cell migration and invasion by decreasing the activity of the PI3K/Akt/NF-κB signaling pathway in vitro.

Vitamin D and melatonin protect the cell's viability and ameliorate the CCl4 induced cytotoxicity in HepG2 and Hep3B hepatoma cell lines

Carbon tetrachloride (CCl4) is widely used to induce liver toxicity in in vitro/in vivo models. Lipid peroxidation (LPO) begins with toxicity and affects cell viability. Recently, the beneficial effects of melatonin and Vitamin D on cell proliferation in human normal and cancer cells were found. This study was planned to evaluate antioxidant and cytoprotective activity of melatonin and Vitamin D in CCl4 induced cytotoxicity in HepG2 and Hep3B hepatoma cell lines. Based on the cytotoxicity assay, melatonin and Vitamin D were evaluated for cytotoprotective potential against CCl4 induced toxicity in HepG2 and Hep3B liver cell lines by monitoring cell viability, LPO and glutathione (GSH) level. Different dosages of CCl4 (0.1, 0.2, 0.3 and 0.4 % v/v) were applied to HepG2 and Hep3B cells in order to determine the most toxic dosage of it in a time dependent manner. The same experiments were repeated with exogenously applied melatonin (MEL) and Vitamin D to groups treated with/without CCL4. Cell viability was determined with MTT measurements at the 2nd, 24th and 48th h. GSH content and Malondialdehyde levels were measured from the cell lysates. As a result, both melatonin and Vitamin D administration during CCl4 exposure protected liver cells from CCl4 induced cell damage. Increase in LPO and decrease in GSH were found in the CCl4 groups of both cells. Contrary to these results administration of MEL and Vitamin D on cells exhibited results similar to the control groups. Therefore, melatonin and Vitamin D might be a promising therapeutic agent in several toxic hepatic diseases.

Prosaposin regulates coenzyme Q10 levels in HepG2 cells, especially those in mitochondria

Coenzyme Q10 (CoQ10) is a key component of the mitochondrial electron transfer chain and is one of the most important cellular antioxidants. We previously reported that glycoprotein saposin B (SapB) binds CoQ10 in human cells. To elucidate the physiological role of SapB and its precursor, prosaposin (Psap), we prepared stable transfectants of HepG2 that overexpress wild-type human Psap (Wt-Tf). We also established a SapB domain mutated Psap (Mt-Tf) in which cysteine(198) was replaced with serine to disrupt three dimensional protein structure by the loss of S-S bridging. Psap knockdown (KD) strains were also examined. Western blotting analysis confirmed overexpression or knockdown of Psap in these HepG2 cells. The cellular ratios of CoQ10 to free cholesterol (FC) significantly decreased in the order of Wt-Tf>parental>Mt-Tf>KD. Additionally, the ratios of CoQ10/FC in mitochondrial fractions decreased in the order of Wt-Tf>parental>KD. These data indicate that Psap and/or SapB regulate CoQ10 levels in HepG2 cells, especially in their mitochondria.

Anticancer nanodelivery system with controlled release property based on protocatechuate-zinc layered hydroxide nanohybrid

BACKGROUND

We characterize a novel nanocomposite that acts as an efficient anticancer agent.

METHODS

This nanocomposite consists of zinc layered hydroxide intercalated with protocatechuate (an anionic form of protocatechuic acid), that has been synthesized using a direct method with zinc oxide and protocatechuic acid as precursors.

RESULTS

The resulting protocatechuic acid nanocomposite (PAN) showed a basal spacing of 12.7 Å, indicating that protocatechuate was intercalated in a monolayer arrangement, with an angle of 54° from the Z-axis between the interlayers of the zinc layered hydroxide, and an estimated drug loading of about 35.7%. PAN exhibited the properties of a mesoporous type material, with greatly enhanced thermal stability of protocatechuate as compared to its free counterpart. The presence of protocatechuate in the interlayers of the zinc layered hydroxide was further supported by Fourier transform infrared spectroscopy. Protocatechuate was released from PAN in a slow and sustained manner. This mechanism of release was well represented by a pseudo-second order kinetics model. PAN has shown increased cytotoxicity compared to the free form of protocatechuic acid in all cancer cell lines tested. Tumor growth suppression was extensive, particularly in HepG2 and HT29 cell lines.

CONCLUSION

PAN is suitable for use as a controlled release formulation, and our in vitro evidence indicates that PAN is an effective anticancer agent. PAN may have potential as a chemotherapeutic drug for human cancer.

The color and size of chili peppers (Capsicum annuum) influence Hep-G2 cell growth

Four types of chili (Capsicum annuum) extracts, categorized according to color; green and red, and size; small and large were studied in Hep-G2 cells. Red small (RS) chili had an LC50 value of 0.378 ± 0.029 compared to green big (GB) 1.034 ± 0.061 and green small (GS) 1.070 ± 0.21 mg/mL. Red big (RB) was not cytotoxic. Capsaicin content was highest in RS and produced a greater percentage sub-G1 cells (6.47 ± 1.8%) after 24 h compared to GS (2.96 ± 1.3%) and control (1.29 ± 0.8%) cells. G2/M phase was reduced by GS compared to RS and control cells. RS at the LC50 concentration contained 1.6 times the amount of pure capsaicin LC50 to achieve the same effect of capsaicin alone. GS and GB capsaicin content at the LC50 value was lower (0.2 and 0.66, respectively) compared to the amount of capsaicin to achieve a similar reduction in cell growth.

Identification of genes in HepG2 cells that respond to DNA methylation and histone deacetylation inhibitor treatment

Previous studies have demonstrated that epigenetics has an important role in the regulation of gene expression in cancer. Epigenetics is the study of reversible, heritable changes in gene function, which occur independently from changes in the DNA sequence. DNA methylation and histone deacetylation are the two most important epigenetic modifications. DNA methylation was one of the first discovered epigenetic modifications and it may lead to changes in chromatin structure, DNA conformation and DNA stability, thereby controlling gene expression. Sample data on the HepG2 cell line from the Gene Expression Omnibus database under GSE5230 accession number were obtained and GEOquery and the limma package were then used to analyze the data and identify differentially expressed genes using Gene Otology. This was conducted in order to investigate the effect on gene expression of inhibiting DNA methylation and histone deacetylation, and to explore the potential role of epigenetics in the development and treatment of hepatic carcinoma. It was found that inhibition of DNA methylation and histone deacetylation affected not only substance metabolism, but also the immune activity in HepG2 cells. Furthermore, common target sites for transcription factors were identified in the differentially expressed genes. It may be concluded that the inhibition of DNA methylation and histone deacetylation contributes to the treatment of hepatic carcinoma and may provide a novel therapeutic strategy for the treatment of hepatic cancer.

Anti-tumor effects of flavonoids from the ethnic medicine Docynia delavayi (Franch.) Schneid. and its possible mechanism

This study investigated the active components and the anti-tumor efficacy and mechanisms of the flavonoids from Docynia delavayi (Franch.) Schneid. (DDS). MTT assay was used to examine the growth inhibitory effects of the four flavonoids, including chrysin, quercetin, naringenin, and avicularin that were isolated from the rhizome of DDS, on human hematomas cell (HepG2), esophageal carcinoma cell (EC109), human cervical adenocarcinoma cell (Hela), human colon adenocarcinoma cell (SW480), and African green monkey kidney cell (Vero cells). The anti-tumor mechanism of chrysin on HepG2 was further investigated by the methods of fluorescence staining, flow cytometry, and immunoblotting. The results showed that the inhibitory activity of chrysin was much stronger than the other three flavonoids on HepG2, EC109, Hela, and SW480 cells for 48 h treatment in vitro. Moreover, no inhibiting effect of chrysin on the proliferation of normal cells (Vero cells) was observed. Further study revealed that chrysin caused HepG2 cell shrinkage, membrane blebbing, and apoptotic body formation, all of which were typical characteristics of apoptosis programmed cell death. Flow cytometric analysis demonstrated that chrysin increased the sub G0/G1 population, which indicated the increased cell apoptosis, thus preventing cells from entering the S phase as the population in G2/M or S phase declined; whereas in G0/G1 phase, it increased. In addition, immunoblot results showed that chrysin significantly increased the expression levels of caspase-3 and Bax proteins, and it decreased the expression level of B-cell lymphoma/leukemia-2 (Bcl-2) protein. These findings indicate that chrysin is the major flavonoid present in DDS, and it induces HepG2 cell death via apoptosis, probably through the participation of caspase-3, Bax, and Bcl-2 proteins.

N-ω-chloroacetyl-l-ornithine, a new competitive inhibitor of ornithine decarboxylase, induces selective growth inhibition and cytotoxicity on human cancer cells versus normal cells

Many cancer cells have high expression of ornithine decarboxylase (ODC) and there is a concerted effort to seek new inhibitors of this enzyme. The aim of the study was to initially characterize the inhibition properties, then to evaluate the cytotoxicity/antiproliferative cell based activity of N-ω-chloroacetyl-l-ornithine (NCAO) on three human cancer cell lines. Results showed NCAO to be a reversible competitive ODC inhibitor (Ki = 59 µM) with cytotoxic and antiproliferative effects, which were concentration- and time-dependent. The EC50,72h of NCAO was 15.8, 17.5 and 10.1 µM for HeLa, MCF-7 and HepG2 cells, respectively. NCAO at 500 µM completely inhibited growth of all cancer cells at 48 h treatment, with almost no effect on normal cells. Putrescine reversed NCAO effects on MCF-7 and HeLa cells, indicating that this antiproliferative activity is due to ODC inhibition.

A novel extraction of trichosanthin from Trichosanthes kirilowii roots using three-phase partitioning and its in vitro anticancer activity

CONTEXT

Three-phase partitioning (TPP), a unique technique which has been explored for protein separation, was used for extraction of trichosanthin (TCS).

OBJECTIVE

TPP was used to optimize the TCS extraction and to determine its anticancer activity.

MATERIALS AND METHODS

The process consists of the simultaneous addition of t-butanol and ammonium sulfate to the aqueous slurry of Trichosanthes kirilowii Maxim (Cucurbitaceae) root powder. The extraction of TCS was optimized with respect to the concentration of ammonium sulfate loading, the ratio of t-butanol to slurry, extraction time and pH. The anticancer activity was performed using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay in vitro.

RESULTS

The extraction time with this technique is lower in comparison to conventional solvent extraction. The optimized protocol resulted in maximum recovery of 98.68% (w/w) protein within 1 h. The in vitro cytotoxic activity of the TCS was evaluated against HepG2 and WRL 68 cancer cell line and results showed that TCS possesses quite highly significant anticancer activity having IC50 values of 10.38 and 15.45 μmol/l, respectively, comparable to standard drugs.

CONCLUSION

This framework is utilized as a basis for optimization for protein separation using TPP technique which is economical and eco-friendly.

Resveratrol protects against alcohol-induced oxidative stress in human HepG2 cells

AIM: To assess the effect of resveratrol as an antioxidant on alcohol-induced oxidative stress in HepG2 cells and to explore the possible mechanisms involved.

METHODS: HepG2 cells were pretreated with resveratrol for 24 h before treatment with alcohol to induce oxidative stress. MTT assay was performed to detect the viability of resveratrol-treated HepG2 cells and control cells. ELISA was used to detect the activity of superoxide dismutase (SOD) and the level of total intracellular reactive oxygen species (ROS). Finally, RT-PCR was performed to detect the expression levels of SOD1, SOD2 and catalase, which are key genes involved in anti-oxidation pathway.

RESULTS: In comparison with control cells (not treated with resveratrol), the toxicity of resveratrol (12.5, 25, 50, 100 μmol/L) towards HepG2 cells during pre-treatment was below 20%. Treatment with 300 mmol/L alcohol without pre-treatment with resveratrol resulted in the death of around 50% of cells. Resveratrol at concentrations ranging from 25 to 100 μmol/L had an antagonistic effect against cytotoxicity of 300 mmol/L alcohol to HepG2 cells. SOD activity was significantly higher in cells pre-treated with 100 mmol/L resveratrol (0.391 ± 0.011) compared to non-treated controls (0.391 ± 0.011 vs 0.286 ± 0.019, P < 0.05). After alcohol induction, non-treated cells showed a higher ROS level compared to cells treated with 25, 50, and 100 μmol/L resveratrol (29234.79 ± 2288.00 vs 18023.26 ± 1359.66, 13528.44 ± 1078.99, 8219.87 ± 635.99). Compared to cells induced with 300 mM alcohol, resveratrol increased the expression levels of SOD1 (0.5535 ± 0.0035, 0.586 ± 0.0113, 0.623 ± 0.0127), SOD2 (1.249 ± 0.011, 1.369 ± 0.028, 1.377 ± 0.021, 1.401 ± 0.0578) and catalase (0.1955 ± 0.004, 0.2275 ± 0.00707).

CONCLUSION: Resveratrol as an antioxidant protects against alcohol-induced oxidative stress by regulating the expression of genes involved in anti-oxidant pathways.

Cytotoxic effects of three new metabolites from Red Sea marine sponge, Petrosia sp

Marine sponges represent an affluent source of biogenetically unprecedented array of biologically active compounds. This study revealed the isolation of ten compounds from marine sponge of Petrosia sp. Their chemical structures were determined by using 1D and 2D NMR, UV, IR and MS measurements. A polyoxygenated steroid (3β,7β,9α-trihydroxycholest-5-en (1), a purine-derivative (3,7-dimethyl-2-(methylamino)-3H-purin-6(7H)-one (2) and a sphingolipid (N-((3S,E)-1,3-dihydroxytetracos-4-en-2-yl)stearamide (3) proved to be new compounds. Meanwhile, seven known compounds; (4-10) were also identified. The cytotoxicity of the total extract and the isolated compounds were subjected to cytotoxicity evaluation employing two cancer cell lines; HepG2 and MCF-7. All tested compounds exhibited cytotoxic effect on both cancer cell lines with IC(50) in range of 20-500 μM. The proposed mechanism of cytotoxic activities was examined through its molecular affinity to the DNA. Compound 5 showed the highest affinity to the DNA with IC(50) 30 μg/mL.

B7-H3 was highly expressed in human primary hepatocellular carcinoma and promoted tumor progression

B7-H3 has been detected in different cancers and correlated to tumor progression and outcome in cancer patients. In this study, we investigated the expression of B7-H3 in tissues and cells of primary hepatocellular carcinoma (PHC) patients. The research showed that B7-H3 is aberrantly expressed in PHC tissues and cells, and its high expression on HepG2 cells significantly promotes cell proliferation, adhesion, migration, and invasion capacity; moreover, it inhibits the proliferation of CD8(+) T cells. Thus, B7-H3 may have a critical role in PHC and it may enhance tumor escape from the immune surveillance of CD8(+) T cells.

Chemotypes sensitivity and predictivity of in vivo outcomes for cytotoxic assays in THLE and HepG2 cell lines

In the present study, we demonstrate the utility of in vitro ATP depletion assays in both THLE and HepG2 cells for predicting the toxicological outcome in Exploratory Toxicology Studies across 446 Pfizer proprietary compounds. Our results suggest a higher likelihood of selecting suitable compounds for in vivo safety studies by using cytotoxicity assays in multiple cell-lines over a single cell line. In addition, we demonstrate that different cell-lines have different sensitivities to compounds depending on their ionization state, that is, acid, base or neutral. HepG2 cells are more sensitive for basic compounds, whereas THLE cells have a relatively higher sensitivity for the acidic and neutral compounds. These in vitro cytotoxicity assays when combined with physicochemical properties (cLogP >3 and topological polar surface area (TPSA) <75Å(2)), are the most effective means to prioritize compounds having a lower probability of causing adverse events in vivo.

Determining oxidative and non-oxidative genotoxic effects driven by estuarine sediment contaminants on a human hepatoma cell line

Estuarine sediments may be reservoirs of hydrophilic and hydrophobic pollutants, many of which are acknowledged genotoxicants, pro-mutagens and even potential carcinogens for humans. Still, studies aiming at narrowing the gap between ecological and human health risk of sediment-bound contaminant mixtures are scarce. Taking an impacted estuary as a case study (the Sado, SW Portugal), HepG2 (human hepatoma) cells were exposed in vitro for 48 h to extracts of sediments collected from two areas (urban/industrial and Triverine/agricultural), both contaminated by distinct mixtures of organic and inorganic toxicants, among which are found priority mutagens such as benzo[a]pyrene. Comparatively to a control test, extracts of sediments from both impacted areas produced deleterious effects in a dose-response manner. However, sediment extracts from the industrial area caused lower replication index plus higher cytotoxicity and genotoxicity (concerning total DNA strand breakage and clastogenesis), with emphasis on micronucleus induction. On the other hand, extracts from the rural area induced the highest oxidative damage to DNA, as revealed by the FPG (formamidopyrimidine-DNA glycosylase) enzyme in the Comet assay. Although the estuary, on its whole, has been classified as moderately contaminated, the results suggest that the sediments from the industrial area are significantly genotoxic and, furthermore, elicit permanent chromosome damage, thus potentially being more mutagenic than those from the rural area. The results are consistent with contamination by pro-mutagens like polycyclic aromatic hydrocarbons (PAHs), potentiated by metals. The sediments from the agriculture-influenced area likely owe their genotoxic effects to metals and other toxicants, probably pesticides and fertilizers, and able to induce reactive oxygen species without the formation of DNA strand breakage. The findings suggest that the mixtures of contaminants present in the assayed sediments are genotoxic to HepG2 cells, ultimately providing a useful approach to hazard identification and an effective line-of-evidence in the environmental monitoring of anthropogenically-impacted coastal ecosystems.

Black rice extract protected HepG2 cells from oxidative stress-induced cell death via ERK1/2 and Akt activation

BACKGROUND/OBJECTIVES

The objective of this study was to evaluate the protective effect of black rice extract (BRE) on tert-butyl hydroperoxide (TBHP)-induced oxidative injury in HepG2 cells.

MATERIALS/METHODS

Methanolic extract from black rice was evaluated for the protective effect on TBHP-induced oxidative injury in HepG2 cells. Several biomarkers that modulate cell survival and death including reactive oxygen species (ROS), caspase-3 activity, and related cellular kinases were determined.

RESULTS

TBHP induced cell death and apoptosis by a rapid increase in ROS generation and caspase-3 activity. Moreover, TBHP-induced oxidative stress resulted in a transient ERK1/2 activation and a sustained increase of JNK1/2 activation. While, BRE pretreatment protects the cells against oxidative stress by reducing cell death, caspase-3 activity, and ROS generation and also by preventing ERKs deactivation and the prolonged JNKs activation. Moreover, pretreatment of BRE increased the activation of ERKs and Akt which are pro-survival signal proteins. However, this effect was blunted in the presence of ERKs and Akt inhibitors.

CONCLUSIONS

These results suggest that activation of ERKs and Akt pathway might be involved in the cytoprotective effect of BRE against oxidative stress. Our findings provide new insights into the cytoprotective effects and its possible mechanism of black rice against oxidative stress.

Chemically crosslinked alginate porous microcarriers modified with bioactive molecule for expansion of human hepatocellular carcinoma cells

Microcarrier is an essential matrix for the large-scale culture of anchorage-dependent cells. In this study, chemical cross-linked alginate porous microcarriers (AMC) were prepared using microemulsion and freeze-drying technology. Moreover, chitosan was coated on the surface of microcarriers (AMC-CS) via electrostatic interactions to improve the mechanical strength. The size of AMC can be modulated through adjusting the concentration of alginate, amount of dispersant and stirring rate. The surface chemical characteristics and morphology of AMC-CS were evaluated by Fourier transformed infrared, X-ray photoelectron spectroscopy, and scanning electron microscope. Fibronectin (Fn) or heparin/basic fibroblast growth factor (bFGF) was then immobilized on the surface of microcarriers via layer-by-layer technology to improve the cytocompatibility. Our data suggested that the size of AMC can be accurately modulated from 90 μm to 900 μm with a narrow size distribution. Micropore structures of AMC-CS were relatively disordered and the pore size ranged between 20 μm and 100 μm. Using AMC after modified with Fn or bFGF as the cell expansion microcarriers, we showed that the proliferation rates of HepG2 cells increased significantly, reaching to more than 30-fold of cell expansion after 10 days of culture, with minor cellular damage caused by the microcarriers. Moreover, the AMC microcarriers modified with Fn or bFGF can increase albumin secretion of HepG2. We suggest that our new modified AMC-based microcarriers will be an attractive candidate for the large-scale cell culture of therapeutic cells.

Proposing a Caco-2/HepG2 cell model for in vitro iron absorption studies

The Caco-2 cell line is well established as an in vitro model for iron absorption. However, the model does not reflect the regulation of iron absorption by hepcidin produced in the liver. We aimed to develop the Caco-2 model by introducing human liver cells (HepG2) to Caco-2 cells. The Caco-2 and HepG2 epithelia were separated by a liquid compartment, which allowed for epithelial interaction. Ferritin levels in cocultured Caco-2 controls were 21.7±10.3 ng/mg protein compared to 7.7±5.8 ng/mg protein in monocultured Caco-2 cells. The iron transport across Caco-2 layers was increased when liver cells were present (8.1%±1.5% compared to 3.5%±2.5% at 120 μM Fe). Caco-2 cells were exposed to 0, 80 and 120 μM Fe and responded with increased hepcidin production at 120 μM Fe (3.6±0.3 ng/ml compared to 2.7±0.3 ng/ml). The expression of iron exporter ferroportin in Caco-2 cells was decreased at the hepcidin concentration of 3.6 ng/ml and undetectable at external addition of hepcidin (10 ng/ml). The apical transporter DMT1 was also undetectable at 10 ng/ml but was unchanged at the lower concentrations. In addition, we observed that sourdough bread, in comparison to heat-treated bread, increased the bioavailability of iron despite similar iron content (53% increase in ferritin formation, 97% increase in hepcidin release). This effect was not observed in monocultured Caco-2 cells. The Caco-2/HepG2 model provides an alternative approach to in vitro iron absorption studies in which the hepatic regulation of iron transport must be considered.

L-Cysteine-induced up-regulation of the low-density lipoprotein receptor is mediated via a transforming growth factor-alpha signalling pathway

Sulphur-containing amino acids regulate plasma cholesterol levels in animals and humans. However, their mechanism of action remains unclear. Low-density lipoprotein receptor (LDLR) plays an important role in cholesterol metabolism. We therefore investigated the effects of sulphur-containing amino acids on the expression of LDLR in hepatocytes. HepG2 cells were cultured in Dulbecco's Modified Eagle's Medium with or without sulphur-containing amino acids and cysteine-containing compounds. We found that L-cysteine increased LDLR mRNA and enhanced LDLR gene promoter activity through the extracellular-signal-related kinase and p38 mitogen-activated protein kinase signalling pathways in HepG2 cells. Moreover, we observed that L-cysteine stimulated the release of transforming growth factor-alpha (TGF-α) and that TGF-α increased the LDLR mRNA levels. This study provides a report of the L-cysteine mediated up-regulation of the LDLR expression via TGF-α signalling pathway. Our findings provide insights into cholesterol homeostasis and amino acid signalling.

Effect of urotensin II on apolipoprotein B100 and apolipoprotein A-I expression in HepG2 cell line

BACKGROUND

Increased apolipoprotein B100 (apo B) and decreased apolipoprotein A-I (apo A-I) production are important risk factors in atherosclerosis. Urotensin II (UII), as the most potent vasoconstrictor in human, is related with hypertension and probably atherosclerosis. Because of the relationship between the hypertension and lipoprotein metabolism in atherosclerosis, the aim of this study was to test the effect of urotensin II on apo B and apo A-I expression in hepatic (HepG2) cell line.

MATERIALS AND METHODS

HepG2 cells were treated with 10, 50, 100, and 200 nmol/L of urotensin II (n = 6). Relative apo B and apo A-I messenger RNA (mRNA) levels in conditioned media, normalized to glyceraldehyde-3-phosphate dehydrogenase, were measured with quantitative real-time polymerase chain reaction method. In addition, apo B and apo A-I levels were also estimated and compared with the controls using the western blotting method. Data were analyzed statistically by ANOVA and non-parametric tests.

RESULTS

The apo B mRNA levels were not increased significantly following the treatment with UII. However, apo B protein levels were increased significantly after the treatment with urotensin II, especially at 100 and 200 nmol/L. The apo A-I mRNA and protein levels in conditioned media also were not significantly changed. However, there was a significant decrease in apo A-I mRNA and protein levels at 200 nM UII.

CONCLUSIONS

UII might increase apo B at protein level probably through participating factors in its synthesis and/ or stability/degradation. In addition, UII may have decreasing effect at more than 200 nM concentrations on apo A-I.

Computational fluid model incorporating liver metabolic activities in perfusion bioreactor

The importance of in vitro hepatotoxicity testing during early stages of drug development in the pharmaceutical industry demands effective bioreactor models with optimized conditions. While perfusion bioreactors have been proven to enhance mass transfer and liver specific functions over a long period of culture, the flow-induced shear stress has less desirable effects on the hepatocytes liver-specific functions. In this paper, a two-dimensional human liver hepatocellular carcinoma (HepG2) cell culture flow model, under a specified flow rate of 0.03 mL/min, was investigated. Besides computing the distribution of shear stresses acting on the surface of the cell culture, our numerical model also investigated the cell culture metabolic functions such as the oxygen consumption, glucose consumption, glutamine consumption, and ammonia production to provide a fuller analysis of the interaction among the various metabolites within the cell culture. The computed albumin production of our 2D flow model was verified by the experimental HepG2 culture results obtained over 3 days of culture. The results showed good agreement between our experimental data and numerical predictions with corresponding cumulative albumin production of 2.9 × 10(-5) and 3.0 × 10(-5)  mol/m(3) , respectively. The results are of importance in making rational design choices for development of future bioreactors with more complex geometries.

Validation of high-throughput genotoxicity assay screening using γH2AX in-cell western assay on HepG2 cells

In vitro genotoxicity tests used in regulatory toxicology studies are sensitive, but the occurrence of irrelevant positive results is high compared with carcinogenicity studies in rodents. Current in vitro genotoxicity tests are also often limited by relatively low throughput. The aim of this study was to validate an in vitro genotoxic assay in a 96-well plate format that allows the simultaneous examination of cytotoxicity and genotoxicity. The test is based on the quantification of the phosphorylation of the histone H2AX (γH2AX), which reflects a global genotoxic insult, using the In-Cell Western technique. The assay was evaluated on HepG2 cells by testing a list of 61 compounds recommended by the European Center for the Validation of Alternative Methods (ECVAM), whose genotoxic potential has already been characterized. The γH2AX assay on HepG2 cell line was highly sensitive: 75% of the genotoxic compounds gave a positive result, and specific: 90-100% of nongenotoxic compounds gave negative results. Compared with the micronucleus genotoxicity assay using the same cell line and test compounds, the γH2AX assay was more sensitive and specific. In sum, the high-throughput γH2AX assay described here can accurately detect simultaneously the genotoxic and the cytotoxic potential of compounds with different modes of mutagenic action, notably those who required metabolic activation. The use of this assay in the early discovery phase of drug development may prove to be a valuable way to assess the genotoxic potential of xenobiotics.

Phytosynergy in some Hypoxis species and pharmacological properties of a Hypoxis-based phytopharmaceutical formula

ETHNOPHARMACOLOGY RELEVANCE

Hypoxis species are used extensively in traditional medicine in southern Africa for several ailments including tuberculosis, chest infections, and nervous and urinary disorders. Several other claims have been made for extracts emanating from Hypoxis species and have led to the production of several commercial products used as immunostimulants mostly for people living with HIV/AIDS and cancer. This study was aimed at investigating the biological activity of four Hypoxis species and a commercial herbal product, 'African potato extract' (APE).

MATERIALS AND METHODS

Antibacterial, antifungal, cyclooxygenase (COX) and acetylcholineasterase (AChE) inhibitory activities of four Hypoxis species (H. acuminata, H. colchicifolia, H. hemerocallidea and H. rigidula) and a popular Hypoxis-based herbal preparation, APE were tested. The phytoconstituents of the mixture were also profiled using TLC methods. Several combinations of the Hypoxis species were prepared and their synergism, additive, autonomic and antagonism effects investigated. As a quality control measure, batch to batch comparison in the phytoconstituents and biological activity of APE was carried out.

RESULTS

The results confirmed H. colchicifolia and H. hemerocallidea as the phytoconstituents of APE. The extracts showed a broad spectrum of activities against the bacterial and fungal strains used. Of particular interest were the activities exhibited by the APE and combinations of H. colchicifolia and H. hemerocallidea. The APE mixture exhibited good antibacterial activity (MIC values of 0.78mg/ml each) in all the tested batches against the bacterial strains used. The water extracts of all four Hypoxis species, three batches of APE and the combination (water extracts) of H. colchicifolia and H. hemerocallidea exhibited high COX-1 and moderate COX-2 inhibitory activity except for H. acuminata which showed low activity against COX-2. All the extract, batches of APE and combinations showed low to moderate AChE inhibitory activity. These results provided some evidence of phytosynergy in some extracts of H. hemerocallidea and H. colchicifolia except for a few extracts which act as additive, autonomous and antagonistic when used to inhibit some bacterial and fungal strains. However, this was not the case for COX and AChE inhibition, as only acetone extracts acted in a synergistic way to reduce the activity of the enzyme.

CONCLUSION

Even though the results give an indication of a positive interaction between some extracts of H. hemerocallidea and H. colchicifolia, the study was carried out on 1:1 v/v combinations only. It is therefore important to carry out isobologram studies, which considers more than one ratio of the combinations.

Programmed hepatocytes cell death associated with FLIP downregulation in response to extracellular preS1/2

Chronic hepatitis B virus (HBV) infection involves liver damage resulting in continuous cell injury and death. During HBV infection, hepatocytes exhibit changes in death receptor expression and in their susceptibility to death. These changes are observed not only in infected cells but also in bystander cells. Because excess viral surface protein (HBsAg) is secreted in large amounts as soluble particles containing preS proteins, the role of soluble preS1/2 in hepatocyte (HepG2) death modulation is an important issue to be explored. An increase of cell death induced by preS1/2 was observed. Also, cell death was associated with the down-regulation of FLIP and activation of caspase 8, caspase 9, and BID. Additionally, hepatocytes exhibited a sensitization to death mediated by the Fas receptor. These results, may contribute to understanding the role of envelope proteins (preS1/2) in the pathogenesis of HBV infection.

Endoplasmic reticulum stress impairs cholesterol efflux and synthesis in hepatic cells

Metabolic disorders such as type 2 diabetes cause hepatic endoplasmic reticulum (ER) stress, which affects neutral lipid metabolism. However, the role of ER stress in cholesterol metabolism is incompletely understood. Here, we show that induction of acute ER stress in human hepatic HepG2 cells reduced ABCA1 expression and caused ABCA1 redistribution to tubular perinuclear compartments. Consequently, cholesterol efflux to apoA-I, a key step in nascent HDL formation, was diminished by 80%. Besides ABCA1, endogenous apoA-I expression was reduced upon ER stress induction, which contributed to reduced cholesterol efflux. Liver X receptor, a key regulator of ABCA1 in peripheral cells, was not involved in this process. Despite reduced cholesterol efflux, cellular cholesterol levels remained unchanged during ER stress. This was due to impaired de novo cholesterol synthesis by reduction of HMG-CoA reductase activity by 70%, although sterol response element-binding protein-2 activity was induced. In mice, ER stress induction led to a marked reduction of hepatic ABCA1 expression. However, HDL cholesterol levels were unaltered, presumably because of scavenger receptor class B, type I downregulation under ER stress. Taken together, our data suggest that ER stress in metabolic disorders reduces HDL biogenesis due to impaired hepatic ABCA1 function.

ERK1/2 regulates hepatocyte Trib1 in response to mitochondrial dysfunction

The TRIB1 locus (8q24.13) is a novel locus identified and replicated by several genome-wide association studies for associations with plasma triglycerides, apolipoprotein B and coronary artery disease. The TRIB1 protein product, tribbles-like protein 1 (Trib1), regulates MAPK activity. MAP kinases transduce a large variety of external signals, leading to a wide range of cellular responses, including growth, differentiation, inflammation and apoptosis. Importantly, Trib1 has been shown to regulate hepatic lipogenesis and very low density lipoprotein production. Despite the relevance of hepatocyte Trib1 to lipid metabolism and atherosclerosis, little is known about the mechanisms regulating Trib1 itself. Here, we identify the mitochondria axis as a regulator of Trib1. Treatment of HepG2 cells with a short pulse of a low oligomycin concentration led to a potent and prolonged increase in the Trib1 mRNA, an effect that was shared with other mitochondria stressors. HuH7 cells as well murine hepatocytes were also responsive albeit to a weaker extent. The upregulation appeared largely independent of reactive oxygen species generation or metabolic stress and was mainly under transcriptional control, with ERK1/2 playing an important regulating role in the process. While the presence of the Trib1 protein could be inferred, attempts to correlate the increased mRNA to changes in protein level were unsuccessful due to the lack of recognizable Trib1 signal. Our data enrich the current paradigm of Trib1 as an activator of the MAPK pathway by uncovering a role for MAPK in regulating Trib1.

TNFR1/TNF-α and mitochondria interrelated signaling pathway mediates quinocetone-induced apoptosis in HepG2 cells

Quinocetone, a new quinoxaline 1, 4-dioxide derivative, has been widely used as an animal feed additive in China. This study was conducted to explore the molecular mechanisms of apoptosis induced by quinocetone in HepG2 cells. MTT assay revealed that the viability of HepG2 cells was significantly inhibited by quinocetone in a dose- and time-dependent manner. Quinocetone-induced apoptosis in HepG2 cells was characterized by cell and nuclei morphology change, cell membrane phosphatidylserine translocation, DNA fragmentation, cleavage of poly (ADP-ribose) polymerase (PARP) and a cascade activation of caspase-8, caspase-9 and caspase-3. Simultaneously, quinocetone induced HepG2 cell cycle arrest, which was supported by overexpression of p21. Cytochrome c release was caused by the mitochondrial membrane potential dissipation, a process related to quinocetone-induced Bid cleavage and elevated Bax/Bcl-2 ratio. Moreover, quinocetone treatment caused the up-regulation of TNF-α and TNFR1 in HepG2 cells. Both soluble TNFR1 receptors and caspase inhibitors suppressed quinocetone-induced apoptosis. In addition, the protein levels of p53, p-p38 and p-JNK were increased in quinocetone-treated cells. Taken together, quinocetone induced apoptosis in HepG2 cells via activation of caspase, interaction of TNF-α and TNFR1 and modulation of the protein levels of Bid, Bax and Bcl-2, involving the participation of p53, p38 and JNK.

Hepatoprotective action of Orthosiphon diffusus (Benth.) methanol active fraction through antioxidant mechanisms: an in vivo and in vitro evaluation

ETHNOPHARMACOLOGICAL RELEVANCE

Preparations of Orthosiphon diffusus (Benth.) have been used by folk medicinal practitioners in the Western Ghats of India for treating inflammation, hepatitis and jaundice for many years and their effectiveness is widely acclaimed among the tribal communities.

AIM OF THE STUDY

To evaluate the mechanisms behind the antioxidant and hepatoprotective potential of Orthosiphon diffusus methanol active fraction (MAF) using in vivo (rat) and in vitro (cell culture) models.

MATERIALS AND METHODS

Neutralization of CCl4-induced hepatotoxicity by MAF was evaluated in rats. Towards this, serum levels of hepatic injury markers (lactate dehydrogenase and alkaline phosphatase), antioxidant enzymes in the liver homogenates, and histological examination were performed. In in vitro studies, mechanisms of neutralization of H2O2-induced toxicity by MAF using MTT, Comet assay and up-regulation of antioxidant enzymes at genetic level (RT-PCR) was performed in HepG2 cells.

RESULTS

Rats pre-treated with Orthosiphon diffusus MAF demonstrated significantly reduced levels of serum LDH (1.3-fold, p<0.05) and ALP (1.6-fold, p<0.05). Similarly, multiple dose MAF administration demonstrated significantly enhanced levels (p<0.05) of antioxidant enzymes in the liver homogenates. Histological analysis revealed complete neutralization of CCl4-induced liver injury by the extract. The in vitro studies demonstrated that, pre-treatment of MAF effectively prevented H2O2-induced oxidative stress, genotoxicity and significantly enhanced (~6-fold, p<0.01) expression of genes for antioxidant enzymes.

CONCLUSIONS

Orthosiphon diffusus MAF demonstrated significant hepatoprotection against CCl4-induced hepatotoxicity by antioxidant mechanisms comparable to silymarin. H2O2-induced oxidative stress was completely neutralized by MAF through enhanced expression of genes for antioxidant enzymes. Therefore, this study validates the use of Orthosiphon diffusus by folk medicinal practitioners in India. Further, MAF of Orthosiphon diffusus can serve as a strong candidate for the development of herbal hepatoprotective agents.

Synthetic cannabinoid quinones: preparation, in vitro antiproliferative effects and in vivo prostate antitumor activity

Chromenopyrazolediones have been designed and synthesized as anticancer agents using the multi-biological target concept that involves quinone cytotoxicity and cannabinoid antitumor properties. In cell cytotoxicity assays, these chromenopyrazolediones have antiproliferative activity against human prostate cancer and hepatocellular carcinoma. It has been shown that the most potent, derivative 4 (PM49), inhibits prostate LNCaP cell viability (IC₅₀ = 15 μM) through a mechanism involving oxidative stress, PPARγ receptor and partially CB₁ receptor. It acts on prostate cell growth by causing G₀/G₁ phase arrest and triggering apoptosis as assessed by flow cytometry measurements. In the in vivo treatment, compound 4 at 2 mg/kg, blocks the growth of LNCaP tumors and reduces the growth of PC-3 tumors generated in mice. These studies suggest that 4 is a good potential anticancer agent against hormone-sensitive prostate cancer.

Chemical-based risk assessment and in vitro models of human health effects induced by organic pollutants in soils from the Olona Valley

Risk assessment of soils is usually based on chemical measurements and assuming accidental soil ingestion and evaluating induced toxic and carcinogenic effects. Recently biological tools have been coupled to chemical-based risk assessment since they integrate the biological effects of all xenobiotics in soils. We employed integrated monitoring of soils based on chemical analyses, risk assessment and in vitro models in the highly urbanized semirural area of the Olona Valley in northern Italy. Chemical characterization of the soils indicated low levels of toxic and carcinogenic pollutants such as PAHs, PCDD/Fs, PCBs and HCB and human risk assessment did not give any significant alerts. HepG2 and BALB/c 3T3 cells were used as a model for the human liver and as a tool for the evaluation of carcinogenic potential. Cells were treated with soil extractable organic matters (EOMs) and the MTS assay, LDH release and morphological transformation were selected as endpoints for toxicity and carcinogenicity. Soil EOMs induced dose-dependent inhibition of cell growth at low doses and cytotoxicity after exposure to higher doses. This might be the result of block of cell cycle progression to repair DNA damage caused by oxidative stress; if this DNA damage cannot be repaired, cells die. No significant inductions of foci were recorded after exposure to EOMs. These results indicate that, although the extracts contain compounds with proven carcinogenic potential, the levels of these pollutants in the analyzed soils were too low to induce carcinogenesis in our experimental conditions. In this proposed case study, HepG2 cells were found an appropriate tool to assess the potential harm caused by the ingestion of contaminated soil as they were able to detect differences in the toxicity of soil EOMs. Moreover, the cell transformation assay strengthened the combined approach giving useful information on carcinogenic potential of mixtures.

MRNA and miRNA expression patterns associated to pathways linked to metal mixture health effects

Metals are a threat to human health by increasing disease risk. Experimental data have linked altered miRNA expression with exposure to some metals. MiRNAs comprise a large family of non-coding single-stranded molecules that primarily function to negatively regulate gene expression post-transcriptionally. Although several human populations are exposed to low concentrations of As, Cd and Pb as a mixture, most toxicology research focuses on the individual effects that these metals exert. Thus, this study aims to evaluate global miRNA and mRNA expression changes induced by a metal mixture containing NaAsO2, CdCl2, Pb(C2H3O2)2·3H2O and to predict possible metal-associated disease development under these conditions. Our results show that this metal mixture results in a miRNA expression profile that may be responsible for the mRNA expression changes observed under experimental conditions in which coding proteins are involved in cellular processes, including cell death, growth and proliferation related to the metal-associated inflammatory response and cancer.

Effect of blueberries (BB) on micronuclei induced by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and 7,12-dimethylbenz(a)anthracene (DMBA) in mammalian cells, assessed in in vitro and in vivo assays

The protective effect of blueberry (BB) on the clastogenic effects of MNNG and DMBA was evaluated with the induced micronucleus (MN) frequency as a biomarker, both in vitro and in vivo. Human hepatoma HepG2 cells, which contain most of the metabolic activating enzymes was used for the in vitro test. MN frequencies were determined in binucleated cells generated by blocking cytokinesis by use of cytochalasin-B. The MN frequency in vivo was determined in polychromatic erythrocytes (PCEs) from the bone marrow of treated mice. BB by itself was not toxic both in vivo and in vitro. There was no evidence of a potential physico-chemical interaction between BB and the test carcinogens in vitro. Pre-treatment with BB reduced the MN frequency induced by MNNG. But, simultaneous treatment and post-treatment with BB did not affect the frequency of MNNG-induced MN. BB did not affect the frequency of DMBA-induced MN in vitro under any test condition. Under in vivo conditions, BB reduced the frequencies of MNNG- and DMBA-induced MN in PCEs, but in the case of the protective effect of BB against DMBA a dramatic reduction in the percentage of PCEs was observed, suggesting increased cytotoxicity.

Synergistic anti-proliferative effect of resveratrol and etoposide on human hepatocellular and colon cancer cell lines

Resveratrol is an active component of grape, which has been shown to inhibit proliferation of a wide variety of tumor cells. The ability of resveratrol to enhance anti-proliferative effects of etoposide in wild type p53 liver carcinoma (HepG2) and colon cancer (HCT-116) cells was investigated with focusing on p53 activation. HepG2 cells and HCT-116 cells were treated with resveratrol and/or etoposide in a time- and dose-dependent manner and their proliferative response was evaluated by XTT assay. The expression of p53 protein was assessed using Western blot. Resveratrol exerted anti-proliferative activity on both cell types in a dose (25-100 μM)- and time (24-72 h)-dependent manner. Interestingly in HepG2 cells, resveratrol exhibited the same levels of cytotoxicity as etoposide (10 μM) when the cells treated with ≥ 25 μM for 48-72 h. In contrast to HepG2, resveratrol significantly enhanced anti-proliferative effects of etoposide in HCT-116 cells. P53 expression was up-regulated by resveratrol and etoposide and pre-incubation of both cells with resveratrol increased levels of etoposide-induced p53 expression. In line with cytotoxicity effect, combination therapy showed stronger activation of p53 in HCT-116 compared to HepG2. It seems that resveratrol exerts differential synergistic effect with etoposide on proliferation of cancer cells from different origin which is mainly accompanied by p53 activation. Our data represent a future strategy to provide much safer and more effective treatment for colon cancer.

Deficiency of insulin-like growth factor 1 attenuates aging-induced changes in hepatic function: role of autophagy

BACKGROUND & AIMS

Circulating insulin-like growth factor-1 (IGF-1) plays a pivotal role in mediating the aging process. This study was designed to evaluate the effect of liver IGF-1 deficiency (LID) on aging-induced changes in hepatic function and underlying mechanisms, with a focus on autophagy.

METHODS

Plasma and liver samples were obtained from young (3-mo) and aged (24-mo) wild type (WT) and LID mice. Levels of AST, ALT, triglyceride, hepatic lipofuscin, steatosis, fibrosis, and nuclear morphology were analyzed. Western blot was employed to evaluate autophagy. Human HepG2 cells were treated with free fatty acid (FFA) to mimic hepatic aging in the absence or presence of IGF-1 siRNA. SA-β-gal activity was detected using flow cytometry and a fluorescence microplate reader. GFP-LC3 was used to assess autophagy activity in HepG2 cells.

RESULTS

Median survival was longer in LID mice compared with WT mice. Aging was associated with elevated levels of triglyceride, AST and ALT, lipofuscin accumulation, steatosis, fibrosis and nuclear injury, which were significantly attenuated by liver IGF-1 deficiency. Levels of autophagy were suppressed in senescent livers, the effect was reversed in the liver of IGF-1 deficient mice. In HepG2 cells, FFA induced the accumulation of β-gal, which was dramatically suppressed by IGF-1 knockdown. Importantly, inhibiting autophagy using 3-methyladenine mitigated IGF-1 knockdown-induced preservation of autophagic vacuole formation and inhibition of β-gal accumulation in the presence of FFA in HepG2 cells.

CONCLUSIONS

Our data revealed that IGF-1 deficiency ameliorated aging-induced hepatic injury, possibly through preventing a concomitant diminution in autophagy. These data provide new insight into the role of IGF-1 and autophagy in the management of aging-induced hepatic injury.

Amelioration by chicory seed extract of diabetes- and oleic acid-induced non-alcoholic fatty liver disease (NAFLD)/non-alcoholic steatohepatitis (NASH) via modulation of PPARα and SREBP-1

We evaluated the effect of chicory (Cichorium intybus L.) seed extract (CI) on hepatic steatosis caused by early and late stage diabetes in rats (in vivo), and induced in HepG2 cells (in vitro) by BSA-oleic acid complex (OA). Different dosages of CI (1.25, 2.5 and 5 mg/ml) were applied along with OA (1 mM) to HepG2 cells, simultaneously and non-simultaneously; and without OA to ordinary non-steatotic cells. Cellular lipid accumulation and glycerol release, and hepatic triglyceride (TG) content were measured. The expression levels of sterol regulatory element-binding protein-1c (SREBP-1c) and peroxisome proliferator-activated receptor alpha (PPARα) were determined. Liver samples were stained with hematoxylin and eosin (H&E). Significant histological damage (steatosis-inflammation-fibrosis) to the cells and tissues and down-regulation of SREBP-1c and PPARα genes that followed steatosis induction were prevented by CI in simultaneous treatment. In non-simultaneous treatment, CI up-regulated the expression of both genes and restored the normal levels of the corresponding proteins; with a greater stimulating effect on PPARα, CI acted as a PPARα agonist. CI released glycerol from HepG2 cells, and targeted the first and the second hit phases of hepatic steatosis. A preliminary attempt to characterize CI showed caffeic acid, chlorogenic acid, and chicoric acid, among the constituents.

Involvement of regucalcin in lipid metabolism and diabetes

Regucalcin (RGN/SMP30) was originally discovered in 1978 as a unique calcium-binding protein that does not contain the EF-hand motif of calcium-binding domain. The regucalcin gene (rgn) is localized on the X chromosome and is identified in over 15 species consisting the regucalcin family. Regucalcin has been shown to play a multifunctional role in cell regulation; maintaining of intracellular calcium homeostasis and suppressing of signal transduction, translational protein synthesis, nuclear deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) synthesis, proliferation, and apoptosis in many cell types. Moreover, regucalcin may play a pathophysiological role in metabolic disorder. The expression of regucalcin is stimulated through the action of insulin in liver cells in vitro and in vivo and it is decreased in the liver of rats with type I diabetes induced by streptozotocin administration in vivo. Overexpression of endogenous regucalcin stimulates glucose utilization and lipid production in liver cells with glucose supplementation in vitro. Regucalcin reveals insulin resistance in liver cells. Deficiency of regucalcin induces an impairment of glucose tolerance and lipid accumulation in the liver of mice in vivo. Overexpression of endogenous regucalcin has been shown to decrease triglyceride, total cholesterol and glycogen contents in the liver of rats, inducing hyperlipidemia. Leptin and adiponectin mRNA expressions in the liver tissues are decreased in regucalcin transgenic rats. Decrease in hepatic regucalcin is associated with the development and progression of nonalcoholic fatty liver disease and fibrosis in human patients. Regucalcin may be a key molecule in lipid metabolic disorder and diabetes.

Silymarin loaded liposomes for hepatic targeting: in vitro evaluation and HepG2 drug uptake

Silymarin has hepatoprotective properties and is used in treatment of various liver diseases, but its bioavailability from oral products is very poor. In order to overcome its poor oral bioavailability we have prepared silymarin loaded hepatic targeting liposomes suitable for parenteral administration. The liposomal formulations were composed of hydrogenated soy phosphatidylcholine and cholesterol with or without distearoylphosphoethanolamine-(polyethyleneglycol)-2000 and various amounts of β-sitosterol β-D-glucoside (Sito-G) as the hepatic targeting moiety. Increasing the amount of Sito-G in the liposomes gradually decreased drug encapsulation efficiencies from ∼70% to ∼60%; still showing promising drug encapsulation efficiencies. Addition of Sito-G to non-PEGylated liposomes clearly affected their drug release profiles and plasma protein interactions, whereas no effect on these was seen for the PEGylated liposomes. Non-PEGylated liposomes with 0.17 M ratio of Sito-G exhibited the highest cellular drug uptake of 37.5% for all of the studied liposome formulations. The highest cellular drug uptake in the case of PEGylated liposomes was 18%, which was achieved with 0.17 and 0.33 M ratio of added Sito-G. The liposome formulations with the highest drug delivery efficacy in this study showed hemolytic activities around 12.7% and were stable for at least 2 months upon storage in 20 mM HEPES buffer (pH 7.4) containing 1.5% Polysorbate 80 at 4 °C and room temperature. These results suggest that the Sito-G containing liposomes prepared in this work have hepatic targeting capability and that they are promising candidates for delivering silymarin to the liver.

Elevated citrate levels in non-alcoholic fatty liver disease: the potential of citrate to promote radical production

Plasma citrate levels were found to be elevated in non-alcoholic fatty liver disease (NAFLD) patients. Cellular experiments indicated that increased citrate levels might originate from an excess of fatty acids. The impact of elevated citrate levels on oxidative stress was examined. It was found that citrate stimulated hydrogen peroxide induced intracellular oxidative stress in HepG2 cells. This was related to the promotion of iron mediated hydroxyl radical formation from hydrogen peroxide by citrate. The stimulating effect of citrate on the reactivity of iron promotes oxidative stress, a crucial process in the progression of NAFLD.

Irreversible electroporation and apoptosis in human liver cancer cells induced by nanosecond electric pulses

The goal of this study was to assess the effect of nanosecond electric pulses on HepG2 human liver cancer cells. Electric pulses with a high strength of 10 kV/cm, duration of 500 ns and frequency of 1 Hz were applied to the cells. After delivery of electric pulses, apoptosis, intracellular calcium ion concentrations, transmembrane mitochondrial potentials, electropermeabilization and recovery from electropermeabilization in cells were investigated. The results showed that electric pulse treatment for 20 s and more could trigger apoptosis in cells. Real-time observation indicated an immediate increase in intracellular calcium ion concentration and a dramatic decrease in mitochondrial membrane potential in cells responding to electric pulses. In subsequent experiments, propidium iodide uptake in cells emerged after exposure to electric pulses, indicating electropermeabilization of the cell membrane. Furthermore, recovery from electropermeabilization was not observed even 4 h after the stimulation, demonstrating that irreversible electropermeabilization was induced by electric pulses. In conclusion, electric pulses with a high strength and nanosecond duration can damage cancer cells, accompanied by a series of intracellular changes, providing strong evidence for the application of electric pulses in cancer treatment.

Overexpression of p42.3 promotes cell growth and tumorigenicity in hepatocellular carcinoma

AIM: To investigate the association of p42.3 expression with clinicopathological characteristics and the biological function of p42.3 in human hepatocellular carcinoma (HCC).

METHODS: We used reverse transcription-polymerase chain reaction (RT-PCR), quantitative real-time RT-PCR and western blotting to detect p42.3 mRNA and protein expression in hepatic cell lines. We examined primary HCC samples and matched adjacent normal tissue by immunohistochemistry to investigate the correlation between p42.3 expression and clinicopathological features. HepG2 cells were transfected with a pIRES2-EGFP-p42.3 expression vector to examine the function of the p42.3 gene. Transfected cells were analyzed for their viability and malignant transformation abilities by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, colony formation assay, and tumorigenicity assay in nude mice.

RESULTS: p42.3 is differentially expressed in primary HCC tumors and cell lines. Approximately 69.6% (96/138) of cells were p42.3-positive in hepatic tumor tissues, while 30.7% (35/114) were p42.3-positive in tumor-adjacent normal tissues. Clinicopathological characteristics of the HCC specimens revealed a significant correlation between p42.3 expression and tumor differentiation (P = 0.031). However, p42.3 positivity was not related to tumor tumor-node-metastasis classification, hepatitis B virus status, or hepatoma type. Regarding p42.3 overexpression in stably transfected HepG2 cells, we discovered significant enhancement of cancer cell growth and colony formation in vitro, and significantly enhanced tumorigenicity in nude mice. Western blot analysis of cell cycle proteins revealed that enhanced p42.3 levels promote upregulation of proliferating cell nuclear antigen, cyclin B1 and mitotic arrest deficient 2.

CONCLUSION: p42.3 promotes tumorigenicity and tumor growth in HCC and may be a potential target for future clinical cancer therapeutics.

Protective Effects of Vitamin C and NAC on the Toxicity of Rifampin on Hepg2 Cells

Rifampin, an antibiotic widely used for the treatment of mycobacterial infections, produces hepatic, renal and bone marrow toxicity in human and animals. In this study, the protective effects of vitamin C and n-acetylcysteine (NAC) on the toxicity of rifampin on HepG2 cells were investigated. Human hepatoma cells (HepG2) were cultured in 96-well M of rifampin in the presence of microplate and exposed to 10, 20, 50 and 100 vitamin C (0.1 mg/mL) and NAC (0.2 mg/mL). Protective effect of the two drugs against rifampin toxicity was assessed by MTT assay. Results show that both vitamin C and NAC significantly inhibited HepG2 cellular damage due to rifampin, and vitamin C was relatively more potent than NAC. Rifampin is metabolized by the liver and its toxic metabolites are responsible for the drug›s hepatic toxicity. Based on our results, it seems that reactive metabolites are the main agents responsible for rifampin hepatotoxicity. The importance of this finding is that if vitamin C or NAC do not affect the antibacterial activity of rifampin, they could be used as preventive agents in rifampin users.

Recombinant human decorin suppresses liver HepG2 carcinoma cells by p21 upregulation

Background

Decorin is a multifunctional molecule of the extracellular matrix and impedes different kinds of tumor cell growth, but the role and molecular mechanism by which decorin inhibits HepG2 cells is not fully understood. Our objective was to construct recombinant human decorin (pcDNA3.1-DCN) and to explore the mechanism by which it inhibits HepG2 cells.

Methods

This experiment was divided into three groups, ie, a control group, an empty vector group, and a pcDNA3.1-DCN group. pcDNA3.1-DCN was constructed using recombinant DNA technology, and the vector for pcDNA3.1-DCN and pcDNA3.1 was then transfected into HepG2 cells using Lipofectamine 2000.

Results

Compared with cells in the control group and in the empty vector group, growth of cells in the pcDNA3.1-DCN group was significantly suppressed, the ratios of cells in the G0/G1 phases and proportion of early apoptotic cells were significantly increased, and the level of p21^WAF1/CIP1 (p21) protein was markedly upregulated (P < 0.05). However, there was no significant difference among the three groups in p53 protein expression (P > 0.05).

Conclusion

The pcDNA3.1-DCN vector was successfully constructed and transfected into HepG2 cells, and decorin overexpression suppressed the growth of HepG2 cells by upregulation of p21 via a p53-independent pathway.

Processed Panax ginseng, Sun Ginseng, Decreases Oxidative Damage Induced by tert-butyl Hydroperoxide via Regulation of Antioxidant Enzyme and Anti-apoptotic Molecules in HepG2 Cells

Potential antioxidant effect of processed ginseng (sun ginseng, SG) on oxidative stress generated by tert-butyl hydroperoxide (t-BHP) was investigated in HepG2 cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and lactate dehydrogenase (LDH) leakage test demonstrated that SG dose-dependently prevents a loss of cell viability against t-BHP-induced oxidative stress. Also, SG treatment dose-dependently relieved the increment of activities of hepatic enzymes, such as aspartate aminotrasferase and alanine aminotransferase, and lipid peroxidation mediated by t-BHP treatment in HepG2 cells. SG increased the gene expression of antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase. However, high dose of SG treatment caused decrease in mRNA level of glutathione peroxidase as compared to low dosage of SG-treated cells. The gene expression of glutathione reductase was found to be slightly increased by SG treatment. In addition, SG extract attributed its hepaprotective effect by inducing the mRNA level of bcl-2 and bcl-xL but reducing that of bax. But, the gene expression of bad showed no significant change in SG-treated HepG2 cells. These findings suggest that SG has hepatoprotective effect by showing reduction of LDH release, activities of hepatic enzymes and lipid peroxidation and regulating the gene expression of antioxidant enzymes and apoptosis-related molecules against oxdative stress caused by t-BHP in HepG2 cells.