EXPRESSION OF CALCIUM-BINDING PROTEIN REGUCALCIN MESSENGER-RNA IN HEPATOMA-CELLS

Whether the gene expression of hepatic Ca2+-binding protein regucalcin is altered in hepatomas was investigated. The change in regucalcin mR NA levels was analyzed by Northern blotting using liver regucalcin com plementary DNA (0.9 kb). Rat hepatoma was induced by continuous feedin g of basal diet containing 0.06% 3'-methyl-4-dimethylaminoazobenzene ( 3'-Me-DAB). After 35 weeks feeding, rats were sacrificed, and the non- tumorous and tumorous tissues of the livers were removed. In individua l rats, the regucalcin mRNA levels in the tumorous tissues were genera lly decreased in comparison with that of the non-tumorous tissues of t he chemical-fed rats, although the chemical administration might decre ase the mRNA expression in normal rat liver, suggesting that the chemi cal administration causes a suppresive effect on the mRNA expression. When the genomic DNA extracted from the liver tumorous tissues was dig ested with restriction enzymes (EcoRI, BamHI and HindIII) and analyzed by Southern blotting, no rear-ranged band was found in the regucalcin gene from the hepatoma. Interestingly, in the transplantable Morris h epatoma cells, the regucalcin mRNA was markedly expressed, while the a lbumin mRNA was expressed only slightly. The present study demonstrate s that regucalcin mRNA is clearly expressed in the transformed cells ( Morris hepatoma cells).