No abstract

We have attempted to generate embryonic stem (ES) cell-derived hepatocytes expressing liver-specific functional properties by use of ES cell technology. It was found that ES cells are allowed to differentiate into hepatocytes possessing high metabolic activities when hepatocyte nuclear factor (HNF)-3beta-transfected ES cells are cultured in alpha-MEM medium supplemented with 10% fetal bovine serum (FBS) and fibroblast growth factor (FGF)-2 in the three-dimensional cell culture system at 5% CO2. The differentiated cells induced albumin, triacylglycerol, urea, and glycogen synthesis as well as further expression of metabolic proteins and serum factors as markers of hepatocytic differentiation for at least 4 months. The cells differentiated from HNF-3beta-transfected ES cells also had hepatocyte-like ultrastructural characteristics, including several endoplasmic reticula, mitochondrion, and glycogen. Our findings indicate that generation of hepatocytes maintaining high metabolic functions developed from mouse ES cells will facilitate the study of the basic mechanism for hepatogenesis and will certainly provide new opportunities for tissue transplantation.

Scirrhous gastric carcinoma is characterized by cancer cells that infiltrate rapidly in the stroma with extensive growth of fibroblasts. In the present study, we examined the effect of gastric fibroblasts on the invasiveness of a Scirrhous gastric cancer cell line, OCUM‐2D, using an invasion assay. Gastric fibroblast‐derived conditioned medium (CM) significantly stimulated the invasiveness of OCUM‐2D cells, as did transforming growth factor‐β (TGF‐β) and hepatocyte growth factor (HGF). The stimulating activity of gastric fibroblast‐derived CM was inhibited significantly by anti‐TGF‐β neutralizing antibody or anti‐HGF neutralizing antibody. TGF‐β and HGF were detected in the gastric fibroblast‐derived CM, and TGF‐β receptor and C‐met (HGF receptor) were expressed on OCUM‐2D cells. Thus, TGF‐β and HGF produced by gastric fibroblasts appear to affect the invasiveness of scirrhous gastric cancer cells. TGF‐β was also detected in the conditioned medium derived from OCUM‐2D cells, though HGF was not. TGF‐β appears to affect the invasiveness of OCUM‐2D cells in both paracrine and autocrine fashions.

No abstract

The Zizyphus jujuba fruit has been used as a traditional Chinese medicinal herb and considered to affect various physiological functions in the body for thousands of years. However, its anti-cancer activity and mechanism of action remain to be elucidated. We investigated the anti-cancer activity of Zizyphus jujuba Mill and its underlining mechanisms of action in human hepatoma cells (HepG2) and found that the extract of Z. jujuba decreased the viability of the cells. Further extraction of the initial Z. jujuba extract with organic solvents revealed that the chloroform fraction (CHCl(3)-F) was the most effective. Interestingly, the CHCl(3)-F induced not only apoptosis but also G1 arrest at a low concentration (100 mug/ml) and G2/M arrest at a higher concentration (200 mug/ml) by cell cycle assay. Apoptosis, an increase in intracellular ROS (reactive oxygen species) level, a decline of mitochondrial membrane potential at low Z. jujuba concentrations, and a ROS-independent mitochondrial dysfunction pathway at high concentrations were all observed. CHCl(3)-F-induced G1 arrest in HepG2 cells was associated with an increase in hypohosphorylation of Rb and p27(Kip1), and a decrease of phosphorylated Rb. However, CHCl(3)-F-induced G2/M arrest in HepG2 cells correlated with a decrease of the p27(Kip1) levels and generation of the phosphorylation of p27(Kip1), however the hypohosphorylation of Rb protein remained. Collectively, our findings suggest that the CHCl(3)-F extract of Z. jujuba extract induced a concentration dependent effect on apoptosis and a differential cell cycle arrest in HepG2 cells.