Development of a gene controlling system with stimulations and its application for prostate cancer treatment

A promoter library was developed that was composed of DNA fragments constructed by randomly elongating cis-acting elements of transcription factors （NFκB, AP-1, Oct-1, p53, Nrf-2). A promoter derivative with randomly introduced mutations showed significantly improved reactivity. The responseof the constructed promoter to X-ray was also observed in vivo. Significant increase in dose-dependent cell killing was also observed when combined suicide gene therapy and X-irradiation.We identified eight miRNAs that are downregulated in response to X-ray irradiation, and inserted artificial target sequences composed of randomly combined complimentary sequences into three representative miRNAs into the 3’UTR of the luciferase gene. The target sequences suppressed the expression, and then released the expression after X-ray irradiation, as expected. When we combined an artificial target sequence with the radiation-responsive promoter, it resulted in a clear-cut gene regulation of expression that was greater than that induced by the promoter alone.