Research Focus

In 1975, Dr. Yamaguchi elucidated the role of liver in the regulation of blood calcium homeostasis and proposed that the liver is a novel target organ of calcitonin, a calcium-regulating hormone. This finding was originally published in Endocrinology (USA). In the course of this research, in 1978, Dr. Yamaguchi discovered a novel protein (gene), located on the X chromosome named "regucalcin" (gene symbol; rgn in PubMed). Regucalcin was shown to play a multifunctional role in various types of cells and tissues and to have a pathophysiological role in various diseases, including diabetes, osteoporosis, Parkinson’s and Alzheimer’s diseases, and malignancies in human subjects. Furthermore, in 2001, while studying transcriptional regulation of regucalcin gene expression, Dr. Yamaguchi et al. discovered a novel protein, called RGPR-p117 (regucalcin gene promoter region related protein; gene symbol; rgpr-p117 in PubMed), which binds to the promoter region of the regucalcin gene.

Since 2013, Dr. Yamaguchi has focused on cancer research to elucidate a potential role of regucalcin as a suppressor in cell growth and carcinogenesis in human subjects. Of note, many studies with proteomics and multiple gene expression profiles demonstrated that the regucalcin gene expression was uniquely downregulated in the tumor tissues of various types of human cancer patients, and that survival was prolonged with high expression of regucalcin in the tumor tissues of patients. Our translational studies demonstrated that overexpressed regucalcin prevented cancer cell growth. Regucalcin was proposed to play a crucial role as a novel suppressor in various types of human malignancies, providing a new strategy with the gene delivery system for cancer therapy. Recently, Dr. Yamaguchi has focused on the involvement of RGPR-p117 in implicating regucalcin gene expression in human cancer.

In addition, Dr. Yamaguchi is engaged in research of the role of medical food factors (nutraceuticals) in the treatment of cancer. Currently, therapeutic agents for bone metastasis and bone lesion are poorly developed. To date, Dr. Yamaguchi et al. have found that the botanical factor curcumin and p-hydroxycinnamic acid, and the marine factor 3,5-dihydroxy-4-methoxybenzyl alcohol inhibit cancer bone metastasis and related bone lesion in vitro and in vivo. These molecules are proposed to be a useful tool as a lead compound in the development of novel anticancer drugs for treatment of metastatic bone cancer.