A novel human hepatoma cell line, FLC-4, exhibits highly enhanced liver differentiation functions through the three-dimensional cell shape

Calculation of the DNA damage yield and relative biological effectiveness in boron neutron capture therapy via the Monte Carlo track structure simulation

Objective.Boron neutron capture therapy (BNCT) is an advanced cellular-level hadron therapy that has exhibited remarkable therapeutic efficacy in the treatment of locally invasive malignancies. Despite its clinical success, the intricate nature of relative biological effectiveness (RBE) and mechanisms responsible for DNA damage remains elusive. This work aims to quantify the RBE of compound particles (i.e. alpha and lithium) in BNCT based on the calculation of DNA damage yields via the Monte Carlo track structure (MCTS) simulation.Approach. The TOPAS-nBio toolkit was employed to conduct MCTS simulations. The calculations encompassed four steps: determination of the angle and energy spectra on the nuclear membrane, quantification of the database containing DNA damage yields for ions with specific angle and energy, accumulation of the database and spectra to obtain the DNA damage yields of compound particles, and calculation of the RBE by comparison yields of double-strand break (DSB) with the reference gamma-ray. Furthermore, the impact of cell size and microscopic boron distribution was thoroughly discussed.Main results. The DSB yields induced by compound particles in three types of spherical cells (radius equal to 10, 8, and 6μm) were found to be 13.28, 17.34, 22.15 Gy Gbp-1for boronophenylalanine (BPA), and 1.07, 3.45, 8.32 Gy Gbp-1for sodium borocaptate (BSH). The corresponding DSB-based RBE values were determined to be 1.90, 2.48, 3.16 for BPA and 0.15, 0.49, 1.19 for BSH. The calculated DSB-based RBE showed agreement with experimentally values of compound biological effectiveness for melanoma and gliosarcoma. Besides, the DNA damage yield and DSB-based RBE value exhibited an increasing trend as the cell radius decreased. The impact of the boron concentration ratio on RBE diminished once the drug enrichment surpasses a certain threshold.Significance. This work is potential to provide valuable guidance for accurate biological-weighted dose evaluation in BNCT.

Geometrical structures for radiation biology research as implemented in the TOPAS-nBio toolkit

Computational simulations, such as Monte Carlo track structure simulations, offer a powerful tool for quantitatively investigating radiation interactions within cells. The modelling of the spatial distribution of energy deposition events as well as diffusion of chemical free radical species, within realistic biological geometries, can help provide a comprehensive understanding of the effects of radiation on cells. Track structure simulations, however, generally require advanced computing skills to implement. The TOPAS-nBio toolkit, an extension to TOPAS (TOol for PArticle Simulation), aims to provide users with a comprehensive framework for radiobiology simulations, without the need for advanced computing skills. This includes providing users with an extensive library of advanced, realistic, biological geometries ranging from the micrometer scale (e.g. cells and organelles) down to the nanometer scale (e.g. DNA molecules and proteins). Here we present the geometries available in TOPAS-nBio.

Transcriptome Analysis Uncovers a Growth-Promoting Activity of Orosomucoid-1 on Hepatocytes

The acute phase protein orosomucoid-1 (Orm1) is mainly expressed by hepatocytes (HPCs) under stress conditions. However, its specific function is not fully understood. Here, we report a role of Orm1 as an executer of HPC proliferation. Increases in serum levels of Orm1 were observed in patients after surgical resection for liver cancer and in mice undergone partial hepatectomy (PH). Transcriptome study showed that Orm1 became the most abundant in HPCs isolated from regenerating mouse liver tissues after PH. Both in vitro and in vivo siRNA-induced knockdown of Orm1 suppressed proliferation of mouse regenerating HPCs and human hepatic cells. Microarray analysis in regenerating mouse livers revealed that the signaling pathways controlling chromatin replication, especially the minichromosome maintenance protein complex genes were uniformly down-regulated following Orm1 knockdown. These data suggest that Orm1 is induced in response to hepatic injury and executes liver regeneration by activating cell cycle progression in HPCs.

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Serum Orm1 levels increased approximately 1.3- to 2.5-folds in both humans and mice after partial hepatectomy.

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Transcriptome analysis revealed that Orm1 mostly induced in hepatocytes as a regulator of mouse liver regeneration.

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Orm1 knockdown in mice impaired liver regeneration with poor hepatocyte growth and suppressed cell cycle signaling.

Orosomucoid-1 (Orm1) is an acute phase protein mainly expressed by hepatocytes under stress conditions. Beginning from the finding that Orm1 was induced after partial hepatectomy in humans and mice, we showed enrichment of Orm1 in regenerating hepatocytes of hepatectomized mice by transcriptome analysis and following culture and animal experiments. Knockdown of Orm1 in mice resulted in decreases in hepatocyte growth accompanying suppressed signaling in controlling chromatin replication. Therefore, Orm1 would be a potential therapeutic and prognostic biomarker for liver diseases, especially after surgical resection of cancer-bearing liver, through its newly found ability to stimulate the cell cycle in regenerating hepatocytes.

Cultured cell-derived decellularized matrices: a review towards the next decade

Summary of recent progress in cell-derived decellularized matrices preparation and application, with perspectives towards the next decade.

Metabolome Analyses Uncovered a Novel Inhibitory Effect of Acyclic Retinoid on Aberrant Lipogenesis in a Mouse Diethylnitrosamine-Induced Hepatic Tumorigenesis Model

Acyclic retinoid (ACR) is a promising drug under clinical trials for preventing recurrence of hepatocellular carcinoma. The objective of this study was to gain insights into molecular basis of the antitumorigenic action of ACR from a metabolic point of view. To achieve this, comprehensive cationic and lipophilic liver metabolic profiling was performed in mouse diethylnitrosamine (DEN)-induced hepatic tumorigenesis model using both capillary electrophoresis time-of-flight mass spectrometry and liquid chromatography time-of-flight mass spectrometry. ACR significantly counteracted against acceleration of lipogenesis but not glucose metabolism in DEN-treated mice liver, suggesting an important role of lipid metabolic reprogramming in the initiation step of hepatic tumorigenesis. Knowledge-based pathway analysis suggested that inhibition of linoleic acid metabolites such as arachidonic acid, a proinflammatory precursor, played a crucial role in the prevention by ACR of DEN-induced chronic inflammation-mediated tumorigenesis of the liver. As a molecular mechanism of the ACR's effect to prevent the aberrant lipogenesis, microarray analysis identified that a key transcription regulator of both embryogenesis and tumorigenesis, COUP transcription factor 2, also known as NR2F2, was associated with the metabolic effect of ACR in human hepatocellular carcinoma cells. Our study provided potential therapeutic targets for the chemoprevention of hepatocellular carcinoma as well as new insights into the mechanisms underlying prevention of hepatic tumorigenesis.

Blood-Compatible Polymer for Hepatocyte Culture with High Hepatocyte-Specific Functions toward Bioartificial Liver Development

The development of bioartificial liver (BAL) is expected because of the shortage of donor liver for transplantation. The substrates for BAL require the following criteria: (a) blood compatibility, (b) hepatocyte adhesiveness, and (c) the ability to maintain hepatocyte-specific functions. Here, we examined blood-compatible poly(2-methoxyethyl acrylate) (PMEA) and poly(tetrahydrofurfuryl acrylate) (PTHFA) (PTHFA) as the substrates for BAL. HepG2, a human hepatocyte model, could adhere on PMEA and PTHFA substrates. The spreading of HepG2 cells was suppressed on PMEA substrates because integrin contribution to cell adhesion on PMEA substrate was low and integrin signaling was not sufficiently activated. Hepatocyte-specific gene expression in HepG2 cells increased on PMEA substrate, whereas the expression decreased on PTHFA substrates due to the nuclear localization of Yes-associated protein (YAP). These results indicate that blood-compatible PMEA is suitable for BAL substrate. Also, PMEA is expected to be used to regulate cell functions for blood-contacting tissue engineering.

Boronophenylalanine, a boron delivery agent for boron neutron capture therapy, is transported by ATB0,+, LAT1 and LAT2

The efficacy of boron neutron capture therapy relies on the selective delivery of boron carriers to malignant cells. p-Boronophenylalanine (BPA), a boron delivery agent, has been proposed to be localized to cells through transporter-mediated mechanisms. In this study, we screened aromatic amino acid transporters to identify BPA transporters. Human aromatic amino acid transporters were functionally expressed in Xenopus oocytes and examined for BPA uptake and kinetic parameters. The roles of the transporters in BPA uptake were characterized in cancer cell lines. For the quantitative assessment of BPA uptake, HPLC was used throughout the study. Among aromatic amino acid transporters, ATB^0,+, LAT1 and LAT2 were found to transport BPA with Km values of 137.4 ± 11.7, 20.3 ± 0.8 and 88.3 ± 5.6 μM, respectively. Uptake experiments in cancer cell lines revealed that the LAT1 protein amount was the major determinant of BPA uptake at 100 μM, whereas the contribution of ATB^0,+ became significant at 1000 μM, accounting for 20–25% of the total BPA uptake in MCF-7 breast cancer cells. ATB^0,+, LAT1 and LAT2 transport BPA at affinities comparable with their endogenous substrates, suggesting that they could mediate effective BPA uptake in vivo. The high and low affinities of LAT1 and ATB^0,+, respectively, differentiate their roles in BPA uptake. ATB^0,+, as well as LAT1, could contribute significantly to the tumor accumulation of BPA at clinical dose.

An efficient system for secretory production of fibrinogen using a hepatocellular carcinoma cell line

AIM

Despite an increasing demand, blood products are not always safe because most are derived from blood donations. One possible solution is the development and commercialization of recombinant fibrinogen, but this process remains poorly developed. This study aimed to develop an effective production system for producing risk-free fibrinogen using human hepatocellular cell lines and serum-free media.

METHODS

Three human liver cancer cell lines (HepG2, FLC-4 and FLC-7) were cultivated in a serum-supplemented medium or two serum-free media (ASF104N and IS-RPMI) to compare their fibrinogen secretion abilities. Fibrinogen subunit gene expression was estimated by quantitative polymerase chain reaction. Massive fibrinogen production was induced using a 5-mL radial flow bioreactor (RFB) while monitoring glucose metabolism. Subsequently, fibrinogen's biochemical characteristics derived from these cells were analyzed.

RESULTS

FLC-7 cell culture combined with IS-RPMI resulted in significantly better fibrinogen production (21.6 μg/10(7) cells per day). ASF104N had more positive effects on cell growth compared with IS-RPMI, whereas fibrinogen production was more efficient with IS-RPMI than with ASF104N. Changing the medium from ASF104N to IS-RPMI led to significantly increased fibrinogen gene expression and glucose consumption. In the RFB culture, the fibrinogen secretion rate of FLC-7 cells reached 0.73 μg/mL per day during a 42-day cultivation period. The subunit composition and clot formation activity of FLC-7 cell-derived fibrinogen corresponded to those of plasma fibrinogen.

CONCLUSION

The FLC-7 cell culture system is suitable for large-scale fibrinogen preparation production.

Hepatocyte polarity

Hepatocytes, like other epithelia, are situated at the interface between the organism's exterior and the underlying internal milieu and organize the vectorial exchange of macromolecules between these two spaces. To mediate this function, epithelial cells, including hepatocytes, are polarized with distinct luminal domains that are separated by tight junctions from lateral domains engaged in cell-cell adhesion and from basal domains that interact with the underlying extracellular matrix. Despite these universal principles, hepatocytes distinguish themselves from other nonstriated epithelia by their multipolar organization. Each hepatocyte participates in multiple, narrow lumina, the bile canaliculi, and has multiple basal surfaces that face the endothelial lining. Hepatocytes also differ in the mechanism of luminal protein trafficking from other epithelia studied. They lack polarized protein secretion to the luminal domain and target single-spanning and glycosylphosphatidylinositol-anchored bile canalicular membrane proteins via transcytosis from the basolateral domain. We compare this unique hepatic polarity phenotype with that of the more common columnar epithelial organization and review our current knowledge of the signaling mechanisms and the organization of polarized protein trafficking that govern the establishment and maintenance of hepatic polarity. The serine/threonine kinase LKB1, which is activated by the bile acid taurocholate and, in turn, activates adenosine monophosphate kinase-related kinases including AMPK1/2 and Par1 paralogues has emerged as a key determinant of hepatic polarity. We propose that the absence of a hepatocyte basal lamina and differences in cell-cell adhesion signaling that determine the positioning of tight junctions are two crucial determinants for the distinct hepatic and columnar polarity phenotypes.

Distinct dedifferentiation processes affect caveolin-1 expression in hepatocytes

BACKGROUND

Dedifferentiation and loss of hepatocyte polarity during primary culture of hepatocytes are major drawbacks for metabolic analyses. As a prominent profibrotic cytokine and potent inducer of epithelial mesenchymal transition (EMT), TGF-β contributes to these processes in liver epithelial cells. Yet, a distinction between culture dependent and TGF-β driven hepatocyte dedifferentiation has not been shown to date.

RESULTS

Here, we show that in both settings, mesenchymal markers are induced. However, upregulation of Snai1 and downregulation of E-Cadherin are restricted to TGF-β effects, neglecting a full EMT of culture dependent hepatocyte dedifferentiation. Mechanistically, the latter is mediated via FAK/Src/ERK/AKT pathways leading to the induction of the oncogene caveolin-1 (Cav1). Cav1 was recently proposed as a new EMT marker, but our results demonstrate Cav1 is not up-regulated in TGF-β mediated hepatocyte EMT, thus limiting validity of its use for this purpose. Importantly, marking differences on Cav1 expression exist in HCC cell lines. Whereas well differentiated HCC cell lines exhibit low and inducible Cav1 protein levels - by TGF-β in a FAK/Src dependent manner, poorly differentiated cell lines display high Cav1 expression levels which are not further modulated by TGF-β.

CONCLUSIONS

This study draws a detailed distinction between intrinsic and TGF-β mediated hepatocyte dedifferentiation and elucidates cellular pathways involved. Additionally, by evaluating the regulation of the oncogene Cav1, we provide evidence to argue against Cav1 as a reliable EMT marker.

Advances in cell sources of hepatocytes for bioartificial liver

BACKGROUND

Orthotopic liver transplantation (OLT) is the most effective therapy for liver failure. However, OLT is severely limited by the shortage of liver donors. Bioartificial liver (BAL) shows great potential as an alternative therapy for liver failure. In recent years, progress has been made in BAL regarding genetically engineered cell lines, immortalized human hepatocytes, methods for preserving the phenotype of primary human hepatocytes, and other functional hepatocytes derived from stem cells.

DATA SOURCES

A systematic search of PubMed and ISI Web of Science was performed to identify relevant studies in English language literature using the key words such as liver failure, bioartificial liver, hepatocyte, stem cells, differentiation, and immortalization. More than 200 articles related to the cell sources of hepatocyte in BAL were systematically reviewed.

RESULTS

Methods for preserving the phenotype of primary human hepatocytes have been successfully developed. Many genetically engineered cell lines and immortalized human hepatocytes have also been established. Among these cell lines, the incorporation of BAL with GS-HepG2 cells or alginate-encapsulated HepG2 cells could prolong the survival time and improve pathophysiological parameters in an animal model of liver failure. The cBAL111 cells were evaluated using the AMC-BAL bioreactor, which could eliminate ammonia and lidocaine, and produce albumin. Importantly, BAL loading with HepLi-4 cells could significantly improve the blood biochemical parameters, and prolong the survival time in pigs with liver failure. Other functional hepatocytes differentiated from stem cells, such as human liver progenitor cells, have been successfully achieved.

CONCLUSIONS

Aside from genetically modified liver cell lines and immortalized human hepatocytes, other functional hepatocytes derived from stem cells show great potential as cell sources for BAL. BAL with safe and effective liver cells may be achieved for clinical liver failure in the near future.

Spherical cell shape of FLC-4 cell, a human hepatoma cell, enhances hepatocyte-specific function and suppresses tumor phenotype through the integration of mRNA-microRNA interaction

The induction mechanism of HNF-4α by spherical cell shape in human hepatoma cells, FLC-4, was investigated. To get insight into the induction mechanism of HNF-4α in three-dimensional FLC-4 cells, mRNA microarray analysis was performed. The gene expression related to drug metabolism and nuclear receptors, such as LXRα, was elevated in spherical FLC-4 cells. We found the first time that the expressions of genes related to malignancy of hepatoma cells, such as HIF-1α, c-Myc and VEGFC, were downregulated by spherical cell shape. Network analysis revealed that HNF-4α would elicit both the enhancement of hepatocyte-specific gene expression and suppression of malignancy. Since HNF-4α gene expression was known to be regulated by microRNA, we inferred that spherical cell shape would induce HNF-4α gene expression through microRNA. To investigate the possibility of such a mechanism, mRNA–microRNA interactions were examined using microRNA microarray and bioinformatics analysis. The level of miR-24, a microRNA targeting HNF-4α, was reduced in spherical FLC-4 cells. On the other hand, spherical cell shape-induced miR-194 and miR-320c would directly downregulate SLC7A5 and E2F1 gene expression, respectively, which are both related to malignancy. Our study suggested that spherical cell shape would induce HNF-4α gene expression and consequent enhancement hepatocyte-specific functions. Spherical cell shape itself would suppress malignancy in FLC-4 cells through microRNA, such as miR-194 and miR-320c.