Construction and utilization of artificial promoters responsive to ultrasound

It is known that ultrasound irradiation could induce intracellular oxidative stress that would be a similar intracellular environment caused by X-ray irradiation. We thus introduce the artificial promoter responsive to X-ray into cells and irradiate the cells with 1 MHz ultrasound at 1 W/cm^2 to see if ultrasound irradiation might cause promoter activation, showing 2-fold increase in gene expression. In addition, the improved one with point mutations showed 6-fold increase in gene expression in response to the ultrasound irradiation. The improved promoter was then stably introduced into the genome of a cell to establish cell lines. Such a cell line was subcutaneously transplanted on to mice. Although it was exposed to ultrasound irradiation after tumor formation, significant increase in gene expression was not observed. We therefore obtained 2 more sensitive promoters to ultrasound irradiation showing more than 10-fold increase in gene expression out of 62 artificial promoter clones constructed similarly to the 11 artificial promoters. One of the two was improved with point mutation introduction and showed more than 20-fold increase in gene expression. We are going to examine activation of the promoter in vivo and its effect on the expression control of therapeutic genes.