Xeno-Free 3D Bioprinted Liver Model for Hepatotoxicity Assessment

Three-dimensional (3D) bioprinting is one of the most promising methodologies that are currently in development for the replacement of animal experiments. Bioprinting and most alternative technologies rely on animal-derived materials, which compromises the intent of animal welfare and results in the generation of chimeric systems of limited value. The current study therefore presents the first bioprinted liver model that is entirely void of animal-derived constituents. Initially, HuH-7 cells underwent adaptation to a chemically defined medium (CDM). The adapted cells exhibited high survival rates (85-92%) after cryopreservation in chemically defined freezing media, comparable to those preserved in standard medium (86-92%). Xeno-free bioink for 3D bioprinting yielded liver models with high relative cell viability (97-101%), akin to a Matrigel-based liver model (83-102%) after 15 days of culture. The established xeno-free model was used for toxicity testing of a marine biotoxin, okadaic acid (OA). In 2D culture, OA toxicity was virtually identical for cells cultured under standard conditions and in CDM. In the xeno-free bioprinted liver model, 3-fold higher concentrations of OA than in the respective monolayer culture were needed to induce cytotoxicity. In conclusion, this study describes for the first time the development of a xeno-free 3D bioprinted liver model and its applicability for research purposes.

Comparison of Alternative Splicing Landscapes Revealed by Long-Read Sequencing in Hepatocyte-Derived HepG2 and Huh7 Cultured Cells and Human Liver Tissue

The long-read RNA sequencing developed by Oxford Nanopore Technologies provides a direct quantification of transcript isoforms, thereby making it possible to present alternative splicing (AS) profiles as arrays of single splice variants with different abundances. Additionally, AS profiles can be presented as arrays of genes characterized by the degree of alternative splicing (the DAS-the number of detected splice variants per gene). Here, we successfully utilized the DAS to reveal biological pathways influenced by the alterations in AS in human liver tissue and the hepatocyte-derived malignant cell lines HepG2 and Huh7, thus employing the mathematical algorithm of gene set enrichment analysis. Furthermore, analysis of the AS profiles as abundances of single splice variants by using the graded tissue specificity index τ provided the selection of the groups of genes expressing particular splice variants specifically in liver tissue, HepG2 cells, and Huh7 cells. The majority of these splice variants were translated into proteins products and appeal to be in focus regarding further insights into the mechanisms underlying cell malignization. The used metrics are intrinsically suitable for transcriptome-wide AS profiling using long-read sequencing.

Polysaccharide and ethanol extracts of Anoectochilus formosanus Hayata: Antioxidant, wound-healing, antibacterial, and cytotoxic activities

Introduction

Polysaccharide and alcohol extracts of Anoectochilus formosanus Hayata have attracted great attention as they exhibit noteworthy properties such as prebiotic and anti-hyperglycemic effects. However, the antioxidant and wound-healing activities of the polysaccharide extract as well as the antibacterial and cytotoxic effects of the ethanol extracts have not been thoroughly uncovered. Therefore, our study investigated these bioactivities of the two extracts prepared from Anoectochilus formosanus to broaden understandings of medical benefits of the plant.

Methods

The monosaccharide composition was analyzed by HPAEC-PAD. The antioxidant and wound-healing activities of the polysaccharide extract were evaluated by ABTS and scratch assays, respectively. The broth dilution method was used to determine the antibacterial ability of the ethanol extract. Additionally, the cytotoxic and mechanistic effects of this extract against hepatocellular carcinoma HUH-7 cells was assessed by MTT assay, qRT-PCR and Western blotting methods.

Results

The polysaccharide extract possessed an effective free radical scavenging ability in an ABTS assay (IC50 = 44.92 μg/ml). The extract also ameliorated wound recovery in a fibroblast scratch assay. Meanwhile, the ethanol extract was able to inhibit the growth of Staphylococcus aureus (MIC = 2500 μg/ml), Bacillus cereus (MIC = 2500 μg/ml), Escherichia coli (MIC = 2500 μg/ml), and Pseudomonas aeruginosa (MIC = 1250 μg/ml). Additionally, it repressed the viability of HUH-7 cells (IC50 = 53.44 μg/ml), possibly through upregulating the expression of caspase 3 (CASP3), CASP8, and CASP9 at both mRNA and protein levels.

Conclusion

The polysaccharide extract of A. formosanus exhibited the antioxidant and wound-healing properties whereas the ethanol extract showed the antibacterial activity and cytotoxicity against HUH-7 cells. These findings specify notable biological effects of the two extracts which could be of potential use in human healthcare.

Nickel chloride induces anticancer biological responses in hepatocellular carcinoma cell lines

Nickel has long been known to have a toxic effect in humans and has been defined as a human carcinogen. However, recent studies have suggested that nickel chloride (NiCl₂) may also possess anticancer properties. The liver is one of the target organs for nickel, and thus, the present study aims to evaluate the effect of NiCl₂ on anticancer biological responses in hepatocellular carcinoma (HCC) cell lines. Both HuH-7, a well-differentiated HCC cell line, and Mahlavu cell line, a poorly differentiated HCC cell line, were exposed to NiCl₂. It was determined that NiCl₂ decreased cell viability in both cell lines in a dose- and time-dependent manner. Nickel chloride exposure at IC50 doses were observed to suppress the ability of HCC cells to produce colonies and also induce apoptosis of HCC cells by increasing Cleaved Caspase-3 protein levels. It was found that NiCl₂ exposure affected cellular morphology, increased the LC3-II protein levels, and induced autophagy in parallel to increased apoptosis in HCC cells. It was also observed that NiCl₂ suppressed cell migration, decreased the size and viability of HCC tumor spheroids generated in 3D cell cultures, and disrupted the spheroid structure of the tumor cells depending on E-cadherin expression levels. Furthermore, it was observed that all anticancer biological responses induced by NiCl₂ occurred independently of the AKT signaling pathway. In conclusion, our results suggested that NiCl₂ induced anticancer biological responses in HCC cell lines. Moreover, this study provided important new molecular and cellular biological basic data about the action mechanisms of NiCl₂ in HCC.

Simultaneous Integration of Gene Expression and Nutrient Availability for Studying the Metabolism of Hepatocellular Carcinoma Cell Lines

How cancer cells utilize nutrients to support their growth and proliferation in complex nutritional systems is still an open question. However, it is certainly determined by both genetics and an environmental-specific context. The interactions between them lead to profound metabolic specialization, such as consuming glucose and glutamine and producing lactate at prodigious rates. To investigate whether and how glucose and glutamine availability impact metabolic specialization, we integrated computational modeling on the genome-scale metabolic reconstruction with an experimental study on cell lines. We used the most comprehensive human metabolic network model to date, Recon3D, to build cell line-specific models. RNA-Seq data was used to specify the activity of genes in each cell line and the uptake rates were quantitatively constrained according to nutrient availability. To integrated both constraints we applied a novel method, named Gene Expression and Nutrients Simultaneous Integration (GENSI), that translates the relative importance of gene expression and nutrient availability data into the metabolic fluxes based on an observed experimental feature(s). We applied GENSI to study hepatocellular carcinoma addiction to glucose/glutamine. We were able to identify that proliferation, and lactate production is associated with the presence of glucose but does not necessarily increase with its concentration when the latter exceeds the physiological concentration. There was no such association with glutamine. We show that the integration of gene expression and nutrient availability data into genome-wide models improves the prediction of metabolic phenotypes.

Luciferase reporter assay for small-molecule inhibitors of MIR92b-3p function: Screening cyanopeptolins produced by Nostoc from the Baltic Sea

We developed a cell sensor that detects the liver cancer-specific microRNA MIR92b-3p, involved in hepatocellular carcinoma development and hepatitis C virus infection. To validate our small-molecule screen that employs a Huh7 human hepatoma cell line stably transfected with a pmirGLO vector containing dual luciferase reporters, we used i) a MIR92b-3p antisense or a MIR92b-3p mimicking agent (concentrations from 0.1 pM to 100 nM), ii) expression of XIST, a long non-coding RNA that is a cellular target of MIR92b, and iii) ectopic expression of Luc2 luciferase. This reporter system was used to test four cyanopeptolins from a de novo library of peptides that were isolated from the Baltic Sea cyanobacteria Nostoc edaphicum strain CCNP1411. Exposure of the Huh7-pmirGLO-MIR92b-3p cells to increasing concentrations (from 10 nM to 100 μM) of the cyanopeptolins and microcystin-LR (MC-LR; a treatment control) did not lead to a dose-dependent restoration of the luciferase signal. Instead, when the reporter cells were treated with MC-LR, the luciferase signal decreased markedly, most likely due to non-target, toxic effects of MC-LR on the cells. Although the first use of this reporter system to screen selected Nostoc peptides did not identify inhibitors of MIR92b, this method provides a means to identify functional miRNA regulators and could be readily extended to other compounds.

Dual Delivery of HNF4α and Cisplatin by Mesoporous Silica Nanoparticles Inhibits Cancer Pluripotency and Tumorigenicity in Hepatoma-Derived CD133-Expressing Stem Cells

Hepatocellular carcinoma (HCC) is one of the most prevalent and deadly malignancies characterized by high rate of recurrence. Tumor recurrence is often attributed to the presence of a subpopulation of cells with stem cell properties, referred to as cancer stem cells (CSCs). Traditionally, cancer therapies target the entire bulk of tumor cells; however, they are poorly effective against CSCs, characterized by higher drug resistance. Therefore, approaches targeting CSCs may be required in addition to conventional chemotherapy to prevent tumor recurrence. In this study, we investigated an approach to target HCC by combining the conventional chemotherapeutic drug, cisplatin, to target the bulk of tumor cells, and differentiation therapy by delivering the gene encoding HNF4α, an important regulator of hepatocyte differentiation, to target CSCs. We used the Huh7 cell line as an in vitro model of HCC, which is characterized by a high proportion of CD133-expressing CSCs. By using flow cytometry, we separated CD133⁺ and CD133^- Huh7 cell subpopulations and have shown that the former has highly pronounced in vivo tumorigenic capacity in contrast to the latter, which could not generate tumors in vivo. For the dual delivery of HNF4α-encoding plasmid and cisplatin, we used polyethyleneimine-modified mesoporous silica nanoparticles (PMSNs) as the nanocarriers. Here, we show that the treatment of CD133-expressing Huh7 cells with HNF4α-loaded PMSNs can suppress their proliferation rate, decrease the proportion of CSCs, downregulate stemness-associated genes, and increase the expression of mature hepatocyte-associated genes. At the same time, the treatment of Huh7 with PMSNs loaded with both HNF4α-encoding plasmid and cisplatin could block them in the S-phase of the cell cycle and cause apoptosis. In addition, dually loaded PMSNs were the most efficient formulation in suppressing tumor growth in vivo. To summarize, in this study, we tested the nanoparticle-based delivery system as both chemotherapy and gene-based therapy agents, which has great potential for development of effective treatment of HCC.

Cyanidin-3-glucoside enhances mitochondrial function and biogenesis in a human hepatocyte cell line

Mitochondrial dysfunction has been identified as one of the primary factors contributing to liver diseases. Pathways that control mitochondrial biogenesis are potential therapeutic targets for the amelioration of hepatocyte dysfunction and liver disease. Research on natural pharmacological agents that ameliorate liver diseases has intensified over the last two decades. Cyanidin-3-glucoside (Cy3g), a dietary flavonoid compound extracted from a wide variety of fruits and vegetables, reportedly has several beneficial health effects. In this study, we used an adult human hepatoma cell line (HuH7) to investigate the effects of the Cy3g polyphenolic compound on mitochondrial function and biogenesis in vitro. An increase in intracellular mitochondrial reductase levels was observed after treatment with Cy3g, but cytotoxicity was not induced. In addition, mitochondrial membrane potential and ATP production were increased following Cy3g treatment. Cy3g treatment also resulted in a dose- and time-dependent upregulation of the gene expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), a transcription factor considered a master regulator of mitochondrial biogenesis and metabolism. Additionally, the expression of sirtuin 1 (SIRT1), which plays a key role in deacetylating PGC-1α, was also increased in a dose- and time-dependent manner. Cy3g treatment also increased the expression of downstream PGC-1α genes, nuclear respiratory factor 1 and mitochondrial transcription factor A (TFAM). Our results suggest that Cy3g has potential as a hepatoprotective therapeutic agent that enhances mitochondrial function and biogenesis in hepatocytes.

Three Dimensional Mixed-Cell Spheroids Mimic Stroma-Mediated Chemoresistance and Invasive Migration in hepatocellular carcinoma

Interactions between cancer cells and cancer-associated fibroblasts (CAFs) within the tumor microenvironment (TME) play an important role in promoting the profibrotic microenvironment and epithelial-mesenchymal transition (EMT), resulting in tumor progression and drug resistance in hepatocellular carcinoma (HCC). In the present study, we developed a mixed-cell spheroid model using Huh-7 HCC cells and LX-2 stellate cells to simulate the in vivo tumor environment with respect to tumor-CAF interactions. Spheroids were cultured from cancer cells alone (monospheroids) or as a mixture (mixed-cell spheroids) in ultra-low-attachment plates. Compact, well-mixed, and stroma-rich mixed-cell spheroids were successfully established with heterotypic cell-cell contacts shown by the presence of gap junctions and desmosomes. Mixed-cell spheroids showed enhanced expression of collagen type-I (Col‐I) and pro‐fibrotic factors such as, transforming growth factor beta1 (TGF-β1), and connective tissue growth factor (CTGF) compared to the levels expressed in mono-spheroids. The EMT phenotype was evident in mixed-cell spheroids as shown by the altered expression of E-cadherin and vimentin. Differential drug sensitivity was observed in mixed-cell spheroids, and only sorafenib and oxaliplatin showed dose-dependent antiproliferative effects. Simultaneous treatment with TGF-β inhibitors further improved sorafenib efficacy in the mixed-cell spheroids, indicating the involvement of TGF-β in the mechanism of sorafenib resistance. In 3D matrix invasion assay, mixed-cell spheroids exhibited fibroblast-led collective cell movement. Overall, our results provide evidence that mixed-cell spheroids formed with Huh-7 and LX-2 cells well represent HCC tumors and their TME in vivo and hence are useful in studying tumor-stroma interactions as mechanisms associated with drug resistance and increased cell motility.

Cell Spheroids with Enhanced Aggressiveness to Mimic Human Liver Cancer In Vitro and In Vivo

We fabricated a spheroid-forming unit (SFU) for efficient and economic production of cell spheroids. We optimized the protocol for generating large and homogenous liver cancer cell spheroids using Huh7 hepatocellular carcinoma (HCC) cells. The large Huh7 spheroids showed apoptotic and proliferative signals in the centre and at the surface, respectively. In particular, hypoxia-induced factor-1 alpha (HIF-1α) and ERK signal activation were detected in the cell spheroids. To diminish core necrosis and increase the oncogenic character, we co-cultured spheroids with 2% human umbilical vein endothelial cells (HUVECs). HUVECs promoted proliferation and gene expression of HCC-related genes and cancer stem cell markers in the Huh7 spheroidsby activating cytokine signalling, mimicking gene expression in liver cancer. HUVECs induced angiogenesis and vessel maturation in Huh7 spheroids in vivo by activating epithelial–mesenchymal transition and angiogenic pathways. The large Huh7 cell spheroids containing HUVECs survived at higher concentrations of anti-cancer drugs (doxorubicin and sorafenib) than did monolayer cells. Our large cell spheroid provides a useful in vitro HCC model to enable intuitive observation for anti-cancer drug testing.

Alginate-embedded HuH-7 cells increase MMP-9 and reduce OCLN expression in vitro

BACKGROUND

Hepatocellular carcinoma is a common cancer, ranking third in cancer-associated deaths. An important cause of cancer patients' mortality is metastasis. At the start of metastasis progression, there is an epithelial-mesenchymal transition, characterized by matrix degradation, junction reductions and vessels formation. HuH-7 is a cell line used in research as an in vitro model for hepatocellular carcinoma. It is known that two-dimensional growth reflects tumor characteristics poorly. In contrast, three-dimensional cultures provide a better approach to the study of tumorigenic potential. The purpose of this work was to mimic a three-dimensional environment in order to assess gene expression of some epithelial-mesenchymal transition and metastasis progression markers in HuH-7 cells and compare them with traditional two-dimensional culture model.

METHODS

HuH-7 cells were encapsulated in sodium alginate (three-dimensional model) to be compared with cells grown in two-dimensional flasks. After 4 days in culture, gene expression of Matrix metallopeptidase 9, Occludin, p65, Intercellular adhesion molecule 1 and Vascular endothelial growth factor A was analyzed by qPCR and cytoskeleton assessment was performed by rhodamine-phalloidin staining.

RESULTS

Differences were found in gene expression, with a high increment of Matrix metallopeptidase 9 and Occludin reduction. The cytoskeleton morphology also showed differences, with a cytoplasm restricted only near the nuclei in the three-dimensional model.

CONCLUSIONS

This work shows the effects of using sodium alginate capsules as a three-dimensional model to the study of HuH-7. Cells in this 3D system show key markers of epithelial-mesenchymal transition, such as Matrix metallopeptidase 9 overexpression and Occludin down-regulation.

Cytotoxic effect of levoglucosenone and related derivatives against human hepatocarcinoma cell lines

Levoglucosenone has been used as template for the synthesis of a wide variety of compounds with an impressive structural variability. However, scarce work has been done regarding the generation of new bioactive entities. Here we report the cytotoxic effect of levoglucosenone and some related derivatives against hepatocarcinoma cell lines. Compounds were obtained in only one synthetic step and one of them showed an activity within the range of IC50 values of cisplatin, a frequently administered chemotherapy drug.

Generation of stable ARE- driven reporter system for monitoring oxidative stress

Background

NF-E2-related factor2 (Nrf2)-antioxidant response element (ARE) signaling pathway is the major defensive mechanism against oxidative stress and is up regulated by specific antioxidants and oxidants to comprise the chemoptotective response. Detection of ARE-activating compounds helps to develop new drugs and identify/quantify the tension range of the oxidants.

Important reasons promoting this work are high throughput, rapid and inexpensive experiments relative to the in vitro studies for ARE-Nrf2 pathway monitoring of chemicals and environmental samples.

Methods

In this study hepatoma Huh7 reporter cell line was generated which contains a luciferase gene under the control of an ARE. This is the first example of ARE construct containing one copy of extended consensus response element. The cells were treated with hydroquinone (HQ) and p-benzoquinone (BQ) (oxidative stress inducers) and the antioxidant, curcumin.

Results

The luciferase activity was induced in a concentration-dependent manner in a concentration range of 1–2 μM for BQ and HQ. Curcumin was also validated as an ARE inducer in concentration above 10 μM. In addition, this reporter cell line provides a rapid detection as early as 4 h to respond to the ARE inducers.

Conclusion

It is a powerful tool for the sensitive and selective screening of chemicals, drugs and environmental samples for their antioxidant and oxidant activities.

Monoterpene (-)-citronellal affects hepatocarcinoma cell signaling via an olfactory receptor

Terpenes are the major constituents of essential oils in plants. In recent years, terpenes have become of clinical relevance due to their ability to suppress cancer development. Their effect on cellular proliferation has made them promising agents in the prevention or treatment of many types of cancer. In the present study, a subset of different monoterpenes was investigated for their molecular effects on the hepatocellular carcinoma cell line Huh7. Using fluorometric calcium imaging, acyclic monoterpene (-)-citronellal was found to induce transient Ca(2+) signals in Huh7 cells by activating a cAMP-dependent signaling pathway. Moreover, we detected the (-)-citronellal-activated human olfactory receptor OR1A2 at the mRNA and protein levels and demonstrated its potential involvement in (-)-citronellal-induced calcium signaling in Huh7 cells. Furthermore, activation of OR1A2 results in phosphorylation of p38 MAPK and reduced cell proliferation, indicating an effect on hepatocellular carcinoma progression. Here, we provide for the first time data on the molecular mechanism evoked by (-)-citronellal in human hepatocellular carcinoma cells. The identified olfactory receptor could serve as a potential therapeutic target for cancer diagnosis and treatment.