Overexpression of regucalcin modulates tumor-related gene expression in cloned rat hepatoma H4-II-E cells

• Published in: Journal of cellular biochemistry 2003-10, Vol.90 (3), p.619-626
• Main Authors: Tsurusaki, Yoshinori, Yamaguchi, Masayoshi
• Format: Article
• Language: English
• Subjects: Animals; c-fos; c-jun; c-myc; Calcium-Binding Proteins - biosynthesis; Cell Division - physiology; Cloning, Molecular; Gene Expression Regulation, Neoplastic - physiology; Genes, myc; Genes, p53; Genes, ras; Ha-ras; hepatoma cells; Intracellular Signaling Peptides and Proteins; Liver Neoplasms, Experimental - genetics; oncogene; p53; Rats; Rats, Wistar; regucalcin; Sulfotransferases; transfectant; Tumor Cells, Cultured
• ISSN: 0730-2312; 1097-4644
• DOI: 10.1002/jcb.10652

Regucalcin is a regulatory protein in intracellular signaling pathway which is related to various protein kinases and protein phosphatases in many cells. The effect of regucalcin on the expression of tumor‐related genes was investigated in the cloned rat hepatoma H4‐II‐E cells and the hepatoma cells (transfectants) overexpressing regucalcin. Hepatoma cells were cultured for 24–72 h in the presence of fetal bovine serum (FBS; 10%). The proliferation of hepatoma cells was significantly suppressed at 24–72 h of culture in regucalcin transfectants as compared with that of wild‐type or mock‐type cells. Western blot analysis showed that regucalcin was markedly expressed in transfectants. The expression of c‐myc, c‐fos, c‐jun, Ha‐ras, and p53 mRNAs was determined using reverse transcription‐polymerase chain reaction (RT‐PCR). Of these genes, the expression of c‐myc or Ha‐ras mRNAs was significantly suppressed in regucalcin transfectants. The suppression of c‐myc mRNA expression in transfectants was confirmed by using Northern blot analysis; significant suppression was seen at 24, 48, or 72 h of culture in the presence of 10% FBS. Culture with 10% FBS significantly enhanced c‐myc mRNA expression in the hepatoma cells (wild‐type) as compared with that of 1% FBS. The enhancement was significantly abolished in the transfectants. Meanwhile, the expression of p53 mRNA in the hepatoma cells was significantly enhanced in regucalcin‐overexpressing hepatoma cells. This study demonstrates that the expression of oncogene c‐myc and Ha‐ras mRNA in hepatoma cells overexpressing regucalcin is suppressed, and that the tumor suppression gene p53 is enhanced in the transfectants. © 2003 Wiley‐Liss, Inc.