A potential role as a suppressor protein of Regucalcin in the development of human carcinogenesis

Regucalcin was discovered in 1978 as a calcium-binding protein. After that, regucalcin was demonstrated to play a multifunctional role as a suppressor protein in signal transduction in various types of cell and tissues. The regucalcin gene (rgn) is localized on the X chromosome. Regucalcin was found to suppress nuclear deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) synthesis in liver cells. Overexpression of endogenous regucalcin possessed suppressive effects on proliferation in the modeled rat hepatoma cells by inhibiting G1 and G2/M cell cycle arrests. Suppressed regucalcin gene expression was found to be associated with progression of hepatocarcinogenesis by proteosome analysis. Moreover, regucalcin mRNA expression was found to suppress in various human normal and tumor tissues including hepatocellular carcinoma, kidney transitional cell carcinoma, brain malignant meningioma, and lung non-small cell carcinoma of human subjects. Suppressed regucalcin gene expression may be a key in development of carcinogenesis. Development of the regucalcin gene deliver system will be expected as a novel gene therapy in clinical aspects for cancer treatment.

Involvement of Regucalcin in Protein Synthesis and Proteolysis: Regulation of the Enzyme Activity in the Cytoplasm and Nucleus

<p>Regucalcin was discovered in 1978 as a novel calcium-binding protein. The name, regucalcin, was proposed for this calcium-binding protein, which regulates various Ca^2+- or Ca²⁺/calmodulin-dependent enzyme activations. The regucalcin gene (gene symbol;rgn) is localized on the X chromosome. Regucalcin has been demonstrated to play a multifunctional role in the regulation of intracellular calcium homeostasis, signal transduction, gene expression, cell proliferation and apoptosis in various types of cells and tissues. The cytoplasmic regucalcin translocases to the nucleus and suppresses nuclear deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) synthesis. Moreover, regucalcin has been shown to reveal a suppressive effect on protein synthesis and a stimulatory effect on protein degradation. Regucalcin has been found to inhibit aminoacyl-tRNA synthetase and activate thiol protease. Â Regucalcin may play a suppressive role in the regulation of protein turnover in cells.</p>