Development of testicular tumor gene therapy using human testicular tumor cell-specific promoters

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One of the most basic issues in gene therapy for cancer is how to express the relevant genes efficiency and specifically in cancer cells. In recent years, there has been an upsurge in basic research into gene therapy for cancer using organ-specific promoters specifically activated in cancer cells and in related clinical trials, with particular attention focused on therapy involving a combination of organ-specific promoters and suicide genes. Motivated by the finding that serum β-HCG (human chorionic gonadotropin) is elevated in over 70% of patients with advanced testicular tumor resistant to chemotherapy, the present study was designed to develop a gene therapy based on the application of a β-HCG promoter as an organ-specific promoter and to investigate its usefulness. It is intended to select a β-HCG promoter with DNA size of 729 base pairs, but we also cloned the DNA of β-HCG promoters of various other sizes, and measured the activity of each promoter in testicular tumor cells in ord … More er to determine the optimal size of a β-HCG promoter for gene therapy. It was found that the cloned β-HCG promoter DNA with 729 base pairs had the best specificity, and this was inserted into a plasmid vector integrated into a luciferase gene. This vector was introduced genetically into a variety of cells-choriocarcinoma cells (JAR), embryonal cancer cells (NEC8, NEC14), prostate cancer cells (PC-3, DU145), and bladder cancer cells (WH), and luciferase activity measured to confirm cell-specific activity in the β-HCG promoter. High levels of promoter activity were observed only in the β-HCG producing choriocarcinoma cells (JAR) and embryonal cancer cells (NEC8, NEC14). Based on these findings, we created an Ad-β-HCG -TK and undertook a similar experiment, in which specific anti-tumor activity was found only in the choriocarcinoma cells (JAR) and the embryonal cancer cells (NEC8, NEC14). No cell-damaging action was observed in normal tissue. Next, in order to explore the development of gene therapy using replication-competent adenovirus vectors, we created one integrating an E1A gene controlled by a ? -HCG promoter. At present, we are engaged in in vivo and in vitro therapy studies using this vector to investigate the optimal gene therapy for human testicular tumors, with the eventual aim of conducting a comparison with gene therapy using suicide genes. Less