LIM In Kyoung Assistant Professor, Ajou University School of Medicine, 教授
HAYASHI Shinichi Researcher, Saitama Cancer Center Res.Inst., 生化学部, 主任研究員 (60144862)
SUEOKA Eisaburo Researcher, Saitama Cancer Center Res.Inst., 血清ウイルス部, 研究員 (00270603)
SUGANUMA Masami Researcher, Saitama Cancer Center Res.Inst., 血清ウイルス部, 主任研究員 (20196695)
Molecular studies on liver cancer development in humans
Hepatocellular carcinoma is one of the common cancers in Asian countries as well as in Africa.The occurence of hepatocellular carcinoma in male patients is significantly higher than in female patients in those countries.To elucidate the sexual diffecnce, we did a molecular analysis of hepatocarcinogenesis in relation to gene expression of hormone receptors.
First, we conduct a two-stage carcinogenesis experiment on rat liver initiated with diethylnitrosamine (DEN), followed by twice-weekly i.p.injections of nodularin, a potent liver tumor promoter, untill week 12.During the process of this experiment, we extracted RNA and DNA from rat liver every 2 weeks to analyze the expression of various genes, such as genes of androgen and estrogen receptors, early response genes and TNF-alpha gene.
We found that a single i.p.administration of nodularin strongly induced jun and fos family of early response genes, as well as TNF-alpha gene in rat
liver.In addition, prolonged expression of these genes depends on stabilization of mRNA in rat liver.We think that mRNA stabilization of early response genes abd TNF-alpha gene is related to potent tumor promoting activity of nodularin.
Next, we studied the expression of androgen and estrogen receptors in the process of liver tumor promotion.To analyze the expression of these genes during hepatocarcinogenesis, we utilized semi-quantitative RT-PCR method using specific primers for androgen and estrogen receptors in rat liver, resulting in quantitative expression of these genes.
To make successful collaboration with our Korean counterparts, we discussed mechanisms of carcinogenesis and cancer chemoprevention with Korean scientists in February this year at Kang-nung National University in Korea, where five Japanese scientists presented new results.We had fruitful scienrific discussion with members of Dr.Lim's laboratory at Ajou University, and with researchers at Seoul National University.We eagerly anticipate the next Symposium in Saitama. Less