[Effect of dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylenedioxybiphenyl-2, 2'-dicarboxylate (DDB) on several phenotypes of Bel-7402 hepatocarcinoma cell line and its mechanism].

DDB is a hepatoprotectant and has been widely used for the treatment of chronic viral hepatitis in China. The drug markedly improved the abnormal liver function particularly in lowering the elevated serum transaminases in patients. It is known that there is a close correlation between primary hepatocarcinoma and chronic viral hepatitis. The aim of the present study is to evaluate the effect of DDB on hepatocarcinoma cell line. The results showed that the growth and clonogenicity of Bel-7402 human hepatocarcinoma cell line cultured with DDB were markedly inhibited. The nucleoles of the cells treated with DDB disappeared or their numbers and nucleus/cytoplasm ratio decreased under electron microscopic observation. DDB at the concentration of 10(-4) mol.L-1 significantly increased the contents of cAMP and calmodulin (CaM) in Bel-7402 hepatocarcinoma cells. DDB was also found to inhibit topoisomerase II activity of Bel-7402 hepatocarcinoma cells. These results suggest that the mechanism of inhibition of DDB on several phenotypes of Bel-7402 cell line may be related to its effect on cAMP and CaM content as well as topoisomerase II activity.