Research / Radiation Carcinogenesis

Kei S. Iwamato,Ph.D.
Adjunct Associate Professor Experimental Radiation Oncology

Iwamoto Research Interests
Broadly, interests are in biological mechanisms of radiation response, especially carcinogenesis, and their exploitation in improvement of radiotherapy.  Specific topics include the following.

• Iodine:  The biological and physical characteristics of iodine are keen interests of the lab.  From a biological perspective, iodine, as both a preventative (nutritional/dietary) and therapeutic (pharmaceutical) factor in breast cancer development and treatment, is being investigated through elucidation of the roles of molecules important in its cellular transport and utilization.  Additionally, from a biophysics perspective, our Monte Carlo, cell, and animal experiments are demonstrating that iodine's interaction with diagnostic-energy x-rays may be exploited to increase radiation dose absorption in tumors using quasi-monochromatic photons or miniature x-ray sources. 
• Insulin-like Growth Factor Type 2 Receptor (M6P/IGF2r): Our data from molecular epidemiological studies on radiation-induced hepatocellular carcinomas (HCC) have led us to the hypothesis that radiation can modulate M6P/IGF2r mRNA stability and thereby regulate its expression and subsequent effects on apoptosis and tumorigenesis.  In vitro experiments using cell lines derived from human breast cancer are being used to test this hypothesis.  Further studies are aiming to identify the presumed binding factors responsible for radiation-induced stabilization of the transcripts. 
• Bone Marrow Derived Stem Cells (BMDSC): BMDSC is one of our model systems for investigating radiation effects on normal tissues. Our experiments have shown that linoleic acid, administered post-exposure, reduces radiation-induced bone marrow cell chromosome aberrations.  These findings are being extended to show a significant reduction in radiation-induced lymphomas in mice.  Effects on lipoxygenase activity is one possible mechanism being investigated. Further, the hypothesis that BMDSC can give rise to radiation-induced non-hematopoietic malignancies is being tested in vivo using a unique mouse model. 
• Proteasome: Radiation has been shown to inhibit proteasome activity.  Fluorescent confocal microscopy techniques have been demonstrated to be highly sensitive for identifying unique radiation-induced localized inhibitory effects in the cell. Therefore, the importance of radiation-induced proteasome inhibition is being studied from the perspective of in cyto and in vivo imaging techniques in the hopes of identifying unique radiation-inhibited proteasomes in individual cells and in tumors growing in mice.