2',4'-Dihydroxy-6'-methoxy-3',5'-dimethylchalcone induced apoptosis and G1 cell cycle arrest through PI3K/AKT pathway in BEL-7402/5-FU cells.

Hepatocellular carcinoma is the fifth most common and the third most lethal cancer worldwide. In recent years, natural flavonoids have drawn great attention as repository for the exploitation of novel antineoplastic agents. 2',4'-Dihydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC), a functional chalcone isolated from the buds of Cleistocalyx operculatus, has been reported to exert potent cytotoxicity against multi-drug resistant BEL-7402/5-FU cells. In this study, the precise mechanisms of DMC-mediated growth inhibition in BEL-7402/5-FU cells were further investigated. DMC was found to trigger apoptosis predominantly via the mitochondria-dependent pathway and the enhancement of reactive oxygen species (ROS) generation. Meanwhile, DMC induced G1 cell cycle arrest through downregulation of cyclin D1 and CDK4. Furthermore, DMC increased p53 level and inhibited NF-κB nuclear-localization via suppression of PI3K/AKT signaling axis, which might be the underlying mechanism of DMC-induced apoptosis and cell cycle arrest in BEL-7402/5-FU cells. Collectively, the study elucidated the mechanisms by which DMC may inhibit the growth of BEL-7402/5-FU cells and suggested the possibility that DMC might be a promising candidate therapeutic agent for hepatoma treatment in the future.

2',4'-Dihydroxy-6'-methoxy-3',5'-dimethylchalcone, a potent Nrf2/ARE pathway inhibitor, reverses drug resistance by decreasing glutathione synthesis and drug efflux in BEL-7402/5-FU cells.

2',4'-Dihydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC) is a major active constituent of the buds of Cleistocalyx operculatus (Roxb.) Merr. et Perry (Myrtaceae), a main ingredient of herbal tea in tropical zones. DMC has been reported to significantly reverse drug resistance in BEL-7402/5-FU cells. Glutathione (GSH) and glutathione S-transferase (GST) play important roles in an efflux system that protects the cells from anticancer drugs. In this study, DMC remarkably decreased the intracellular GSH content and GST activity. Furthermore, DMC suppressed the expression of factor erythroid 2-related factor 2 (Nrf2), prevented Nrf2 nuclear translocation, and inhibited the binding of Nrf2 to the antioxidant response element (ARE). The glutamate-cysteine ligase catalytic subunit (GCLC) and glutamate-cysteine ligase modifier subunit (GCLM) were down-regulated by inhibiting Nrf2 with DMC treatment. These results suggested that DMC reduced drug efflux to reverse drug resistance by suppressing the Nrf2/ARE signaling pathway in human hepatocellular carcinoma BEL-7402/5-FU cells.

Purpose-driven biomaterials research in liver-tissue engineering.

Bottom-up engineering of microscale tissue ("microtissue") constructs to recapitulate partially the complex structure-function relationships of liver parenchyma has been realized through the development of sophisticated biomaterial scaffolds, liver-cell sources, and in vitro culture techniques. With regard to in vivo applications, the long-lived stem/progenitor cell constructs can improve cell engraftment, whereas the short-lived, but highly functional hepatocyte constructs stimulate host liver regeneration. With regard to in vitro applications, microtissue constructs are being adapted or custom-engineered into cell-based assays for testing acute, chronic and idiosyncratic toxicities of drugs or pathogens. Systems-level methods and computational models that represent quantitative relationships between biomaterial scaffolds, cells and microtissue constructs will further enable their rational design for optimal integration into specific biomedical applications.

Exploitation of physical and chemical constraints for three-dimensional microtissue construction in microfluidics.

There are a plethora of approaches to construct microtissues as building blocks for the repair and regeneration of larger and complex tissues. Here we focus on various physical and chemical trapping methods for engineering three-dimensional microtissue constructs in microfluidic systems that recapitulate the in vivo tissue microstructures and functions. Advances in these in vitro tissue models have enabled various applications, including drug screening, disease or injury models, and cell-based biosensors. The future would see strides toward the mesoscale control of even finer tissue microstructures and the scaling of various designs for high throughput applications. These tools and knowledge will establish the foundation for precision engineering of complex tissues of the internal organs for biomedical applications.

Predicting in vivo anti-hepatofibrotic drug efficacy based on in vitro high-content analysis.

BACKGROUND/AIMS: Many anti-fibrotic drugs with high in vitro efficacies fail to produce significant effects in vivo. The aim of this work is to use a statistical approach to design a numerical predictor that correlates better with in vivo outcomes. METHODS: High-content analysis (HCA) was performed with 49 drugs on hepatic stellate cells (HSCs) LX-2 stained with 10 fibrotic markers. ~0.3 billion feature values from all cells in >150,000 images were quantified to reflect the drug effects. A systematic literature search on the in vivo effects of all 49 drugs on hepatofibrotic rats yields 28 papers with histological scores. The in vivo and in vitro datasets were used to compute a single efficacy predictor (E(predict)). RESULTS: We used in vivo data from one context (CCl(4) rats with drug treatments) to optimize the computation of E(predict). This optimized relationship was independently validated using in vivo data from two different contexts (treatment of DMN rats and prevention of CCl(4) induction). A linear in vitro-in vivo correlation was consistently observed in all the three contexts. We used E(predict) values to cluster drugs according to efficacy; and found that high-efficacy drugs tended to target proliferation, apoptosis and contractility of HSCs. CONCLUSIONS: The E(predict) statistic, based on a prioritized combination of in vitro features, provides a better correlation between in vitro and in vivo drug response than any of the traditional in vitro markers considered.

Galactosylated cellulosic sponge for multi-well drug safety testing.

Hepatocyte spheroids can maintain mature differentiated functions, but collide to form bulkier structures when in extended culture. When the spheroid diameter exceeds 200 µm, cells in the inner core experience hypoxia and limited access to nutrients and drugs. Here we report the development of a thin galactosylated cellulosic sponge to culture hepatocytes in multi-well plates as 3D spheroids, and constrain them within a macroporous scaffold network to maintain spheroid size and prevent detachment. The hydrogel-based soft sponge conjugated with galactose provided suitable mechanical and chemical cues to support rapid formation of hepatocyte spheroids with a mature hepatocyte phenotype. The spheroids tethered in the sponge showed excellent maintenance of 3D cell morphology, cell-cell interaction, polarity, metabolic and transporter function and/or expression. For example, cytochrome P450 (CYP1A2, CYP2B2 and CYP3A2) activities were significantly elevated in spheroids exposed to ß-naphthoflavone, phenobarbital, or pregnenolone-16α-carbonitrile, respectively. The sponge also exhibits minimal drug absorption compared to other commercially available scaffolds. As the cell seeding and culture protocols are similar to various high-throughput 2D cell-based assays, this platform is readily scalable and provides an alternative to current hepatocyte platforms used in drug safety testing applications.

Rapid construction of mechanically- confined multi- cellular structures using dendrimeric intercellular linker.

Tissue constructs that mimic the in vivo cell-cell and cell-matrix interactions are especially useful for applications involving the cell- dense and matrix- poor internal organs. Rapid and precise arrangement of cells into functional tissue constructs remains a challenge in tissue engineering. We demonstrate rapid assembly of C3A cells into multi- cell structures using a dendrimeric intercellular linker. The linker is composed of oleyl- polyethylene glycol (PEG) derivatives conjugated to a 16 arms- polypropylenimine hexadecaamine (DAB) dendrimer. The positively charged multivalent dendrimer concentrates the linker onto the negatively charged cell surface to facilitate efficient insertion of the hydrophobic oleyl groups into the cellular membrane. Bringing linker- treated cells into close proximity to each other via mechanical means such as centrifugation and micromanipulation enables their rapid assembly into multi- cellular structures within minutes. The cells exhibit high levels of viability, proliferation, three- dimensional (3D) cell morphology and other functions in the constructs. We constructed defined multi- cellular structures such as rings, sheets or branching rods that can serve as potential tissue building blocks to be further assembled into complex 3D tissue constructs for biomedical applications.