[Screening for Biological Marker of Dose-optimization in Cancer Radiotherapy]

External radiotherapy of target regions using high-energy beams leads to excessive exposure along with individual variation in therapeutic and adverse effects. However, high-precision radiotherapy utilizes 3D-multi detector computed tomography to confirm both target position and administer radiation dose. To install the individual bioinformation in the radiotherapy plan (particularly, radiosensitivity into the target region and/or the around normal tissue), the investigation of biomarkers, which are able to estimate their radiosensitivity was performed. The aim of this investigation is to screen for suitable radiosensitivity biomarkers using the human colorectal cancer-derived HCT 116 cell line.

We found that cell damage and micronucleus frequency significantly increased dose dependently after exposure to 6 Gy X-irradiation (1 Gy/min). In contrast, total RNA concentration (69.8-85.2 ng/ml) remained stable in the cell culture supernatant despite radiation dose variation. Additionally, 52 specific micro RNAs were detected after exposure to 6 Gy X-irradiation.

These results suggest that radiosensitivity, including extent of cellular damage in target or normal tissue, can be indirectly estimated by monitoring the expression of micro RNAs.