Go Kagiya

Construction of X-ray-inducible promoters through cis-acting element elongation and error-prone polymerase chain reaction

A promoter that is activated by ionizing radiation may be a useful tool for cancer therapy since, with such a promoter, the therapeutic gene can be expressed only in cancer tissues by irradiation. An artificially constructed promoter is advantageous as natural promoters may have physiological limitations. However, reasonably designing a promoter is hampered by shortage of information about the relationship between the structure and properties of a promoter DNA.

Identification of a cis-Acting Element Responsive to Ultrasound in the 5′-Flanking Region of the Human Heme Oxygenase-1 Gene

We previously found that the heme oxygenase-1 gene (hmox-1) was the most upregulated gene among 9,182 genes in human lymphoma U937 cells exposed to a 1-MHz continuous ultrasound using the cDNA microarray technique. However, little is known about the molecular mechanisms of the induction of hmox-1 expression by ultrasound. We investigated the mechanism using human prostate cancer DU145 cells in which expression of hmox-1 increased with sonication in a time and an intensity-dependent manner. When N-acetyl-L-cysteine or glutathione-monoethyl ester, a potent antioxidant, was added to cell culture, hmox-1 upregulation was attenuated, suggesting that oxidative stress caused by sonication is involved in this process. To identify cis-acting elements required for the ultrasound-mediated induction, we carried out transient expression assays with plasmids carrying the luciferase gene under control of deletion mutants of the 5-flanking region of hmox-1. The results revealed that the upregulations by sonication were observed with deletion mutants carrying the E1 or E2 enhancer of the 5-flanking region, suggesting stress-responsive elements (StRE) were involved in the induction because either enhancer contains a number of the element. Indeed, site-directed mutations within StRE decreased the reactivity of deletion mutants to sonication. A transcription factor NF-E2-related Factor 2 that binds to StRE would therefore be activated by oxidative stress induced by sonication.

QA/QC of Proton Therapy at WERC

Since June 2002 we have treated 28 patients with prostate cancer and 2 patients with liver cancer using the accelerator complex that consists of a 5 MV tandem and a 200 MeV synchrotron (W-MAST). The QA/QC activities for proton therapy at WERC has been performed such as the check of the soundness of the irradiation system including the monitors system, ridge filters, compensators, wobbler magnets, and water and air systems, and the positioning system including positioning with CT installed adjacent to the irradiation port and so on. We report the details of the QA/QC activities that are performed daily, weekly and yearly, and results like the long-term trend of the dose monitor in WERC. In addition we show some experiences that prevent therapeutic troubles from occurring due to the systematic and human errors.

Ultrasound‐Mediated Transfection Enhanced by Cavitation Facilitation and Membrane Modification

The mechanism of ultrasound‐mediated transfection (USMT) was explored to get a better understanding and improvement of the efficiency. Efficiency of USMT was linked to cavitational effects and also to plasma membrane conditions. These results indicate that the mechanism underlying USMT is possibly explained by the interaction between the cavitational effect and a plasma membrane response. When both were combined, transfection efficiency was significantly enhanced in vitro and in vivo. This enhancement could be useful for ultrasound‐mediated gene therapy in the future.

Bioeffects of Ultrasound: Apoptosis and Change of Gene Expression Induced by Ultrasound and Their Therapeutic Utilization

Human lymphoma U937 cells were sonicated with 1 MHz (continuous wave) at 4.9 W/cm2 and incubated, and apoptosis and change of gene expression were examined. After 6 hrs significant apoptosis was observed and two up‐ and two down‐regulated genes were identified.