Byung Chae Park

In vitro induction of differentiation by ginsenosides in F9 teratocarcinoma cells

The aim of this study was to determine the ability of the ginsenosides, extracts of Panax ginseng C.A. Meyer, to cause differentiation of F9 teratocarcinoma stem cells as a model system. F9 stem cells cultured in the presence of the ginsenosides together with dibutyryl cyclic AMP (dbcAMP) became parietal endoderm-like cells. Moreover, the expression of differentiation marker genes, such as laminin B1 and type IV collagen, was increased after treatment with the ginsenosides. Among the various purified ginsenosides, Rh1 and Rh2 were the most effective at causing differentiation of F9 cells. Since ginsenosides and glucocorticoid hormone have similar chemical structures, we examined the possibility of the involvement of a glucocorticoid receptor (GR) in the differentiation process induced by the ginsenosides. According to Southwestern blot analysis, a 94 kDa protein regarded as a GR was detected in F9 cells cultured in the medium containing the ginsenosides Rh1 or Rh2. In addition, F9 stem cells treated with the ginsenosides Rh1 or Rh2 and with RU486, a glucocorticoid antagonist with a high affinity for the GR, did not differentiate into endoderm cells morphologically, and the expression of laminin B1 gene was not induced in these cells. In a gel mobility shift assay, protein factors capable of binding to the glucocorticoid responsive element (GRE) specifically were detected in nuclear extracts of the ginsenoside-treated F9 cells. Moreover, overexpression of GR by cotransfection of GR expression vector and GRE-luciferase vector enhanced the transactivation activity of GRE promoter in the presence of ginsenosides Rh1 or Rh2 and was further augmented by dbcAMP. In addition, ginsenosides Rh1 and Rh2 bound to a GR assessed by whole-cell binding assay, even though the specific binding affinity was weaker compared to dexamethasone. Based on these data, we suggest that the ginsenosides Rh1 and Rh2 cause the differentiation of F9 cells and the effects of ginsenosides might be exerted via binding with a GR or its analogous nuclear receptor.

Insulin-like growth factor II (IGF-II) secreted from HepG2 human hepatocellular carcinoma cells shows angiogenic activity.

Hepatocellular carcinoma (HCC) is a typical hypervascular tumor. Since insulin-like growth factor II (IGF-II) has been reported to play a significant role in liver regeneration and hepatocarcinogenesis, we initially examined its angiogenic effect on the chorioallantoic membrane (CAM) of 9-day-old chick embryos. We also investigated whether IGF-II secreted from HepG2 human hepatocellular carcinoma cells induces vascularization using the chick embryo CAM. We found that the concentrated conditioned media (CCM) of HepG2 cell culture induced angiogenesis on the CAM. We also identified IGF-II protein in the CCM from HepG2 cells by Western blot analysis. However, CCM from Chang liver cells, which are normal human liver cells and were free of IGF-II, did not induce angiogenesis in the CAM. These results suggest that IGF-II secreted from hepatocellular carcinoma cells may act as an angiogenic factor for the hypervascularization of HCC.

Differential expression of transforming growth factor a and insulin-like growth factor II in chronic active hepatitis B, cirrhosis and hepatocellular carcinoma

In the present study we investigated the expression of transforming growth factor alpha and insulin-like growth factor II to explain the role of these growth factors in the development of hepatocellular carcinoma from chronic active hepatitis B and cirrhosis. The expression of transforming growth factor alpha and insulin-like growth factor II was tested in 38 tissue samples from patients with chronic active hepatitis B, 32 cirrhosis and 31 hepatocellular carcinoma, by immunohistochemical staining using monoclonal anti-transforming growth factor alpha and anti-insulin-like growth factor II. All patients were seropositive for HBsAg. Transforming growth factor alpha was expressed in 26 (68.4%) of 38 chronic active hepatitis B, 18 (56.3%) of 32 cirrhosis and 16 (51.6%) of 31 hepatocellular carcinoma tissue samples. Transforming growth factor alpha was found in the periportal hepatocytes of chronic active hepatitis B and in regenerating hepatocytes of cirrhotic nodules. In hepatocellular carcinoma tissues, transforming growth factor alpha-containing tumor cells were evenly distributed within the tumor tissues but focal distribution limited to a part of tumor tissues was also observed. The expression of insulin-like growth factor II was observed in 30 (93.8%) of 32 cirrhosis and all the 31 hepatocellular carcinoma tissue samples tested, but not in chronic active hepatitis B samples. Insulin-like growth factor II was expressed in most hepatocytes of regenerating nodules and in tumorous as well as non-tumorous hepatocytes of hepatocellular carcinoma tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Involvement of glucocorticoid receptor in the induction of differentiation by ginsenosides in F9 teratocarcinoma cells

We have previously reported that ginsenosides Rh1 and Rh2 induced the differentiation of F9 teratocarcinoma stem cells [Lee, Y. N., Lee, H. Y., Chung, H. Y., Kim, S. I., Lee, S. K., Park, B. C. and Kim, K. W., In vitro induction of differentiation by ginsenosides in F9 teratocarcinoma cells. Eur. J. Cancer 1996, 32, 1420-1428.]. Since the chemical structure of Rh1 and Rh2 is very similar to that of dexamethasone, a synthetic glucocorticoid, we investigated whether Rh1 and Rh2 act through the glucocorticoid receptor (GR). Immunocytochemistry showed that Rh1 or Rh2 increased the nuclear translocation of GR in the same manner of dexamethasone. In the gel shift assay, glucocorticoid response element (GRE) binding protein in F9 cells was increased by Rh1 or Rh2. To confirm whether the increased binding protein is GR, we performed the competition assay with unlabeled GRE as a specific competitor. Moreover, supershift assay with the GR antibody showed that the binding proteins are GR. In addition, to confirm the Rh1 or Rh2-induced transactivation of GRE promoter, we cotransfected GR expression vector and GRE-luciferase vector. In the luciferase assay, Rh1 or Rh2 potently induced luciferase activity and this induction was blocked by RU486, a potent GR antagonist. Taken together, we suggest that ginsenosides Rh1 and Rh2 may induce the differentiation of F9 cells by stimulating the nuclear translocation of GR.

Prevalence of hepatitis C antibody in patients with chronic liver disease and hepatocellular carcinoma in Korea

Summary. To investigate the contribution of hepatitis C virus (HCV) to chronic liver disease and hepatocellular carcinoma (HCC) in Korea, antibodies to HCV (anti‐HCV) were tested by enzyme immunoassay in 1759 patients with chronic liver disease and HCC, and in 808 healthy adults. The prevalence of anti‐HCV was 1.6% in 808 controls. Anti‐HCV was present in 32 (7.7%) of 418 hepatitis B surface antigen (HBsAg)‐positive and 128 (53.1%) of 241 HBsAg‐negative patients with chronic hepatitis, 16 (6.0%) of 265 HBsAg‐positive and 90 (30.5%) of 295 HBsAg‐negative patients with liver cirrhosis, and 16 (4.8%) of 330 HBsAg‐positive and 61 (29.0%) of 210 HBsAg‐negative patients with HCC. Antibodies to hepatitis B core antigen (anti‐HBc) were present in 80–88% of patients who were seropositive for anti‐HCV and seronegative for HBsAg. Among the sera from 114 patients with HBsAg‐negative and anti‐HCV‐positive chronic liver diseases, HBV DNA and HCV RNA were detected by polymerase chain reaction (PCR) in 54 (47.4%) and 61 (53.3%), respectively. Both HBV DNA and HCV RNA were detected in 4 (4.4%) samples. The mean age of the patients with both HBsAg and anti‐HCV was not different from that of patients who were seropositive for HBsAg alone. These findings indicate that current and/or past HBV infection is still the main cause of chronic liver disease in Korea. Although multivariate analysis showed that anti‐HCV is a risk factor for chronic hepatitis, cirrhosis of the liver and HCC, PCR data for HBV DNA and HCV RNA indicate that HCV infection plays only a minor role in HBsAg‐positive as well as in HBsAg‐negative liver disease and does not accelerate the development of HCC in HBV carriers.

Study on the Expression of Insulin-like Growth Factor II (IGF- II) in Hepatocellular Carcinoma Cells and Developing Rat Embryos

PURPOSE The insulin-like growth factor II (IGF-II) gene expresses a family of transcripts in embryonic/fetal tissue, and also highly was expressed during hepatocellular carcinogenesis. In this study, we showed that IGF-II mRNA and protein levels are detected in rat embryo, HepG2 human hepatoma cells and Chang liver cells. MATERIALS AND METHODS This study included sections of rat embryos 7~17 days post coitum (d.p.c), HepG2 cells and Chang liver cells. Using immunohistochemistry, Northern blotting and Western blotting, we observed the expression of IGF-II in the rat embryo, HepG2 cells and Chang liver cells. RESULTS We localized IGF-II gene products in sections of rat embryo 7~17 d.p.c by performing immunohistochemistry. The IGF-II was mainly expressed in the proximal endoderm and ectoplacental cone between 7 and 9 d.p.c. At 10 d.p.c. the expression was localized at the heart primodium as well as the proximal endoderm, and at 11 d.p.c. the IGF-II was expressed in the liver and heart. After 12 d.p.c. and 14 d.p.c., the expression was also detected in the brain, muscle and bone, and head mesenchyme, respectively. While the expression of IGF-II protein was not detected in the normal adult liver, intense staining was detected in the heart, liver and choroids plexus at 17 d.p.c. CONCLUSION These results suggest that IGF-II may act as an oncofetal protein during hepatocellular carcinogenesis and embryogenesis.