EFNA1, a radioresistant marker, detected in a murine tumor model by gamma and carbon ion irradiation

Using single-color oligo-microarrays, we analyzed the gene expression profiles of two murine squamous cell carcinomas: NR-S1 (radioresistant) and SCCVII (radiosensitive), after irradiation with 137-Cs gamma rays at doses of 30, 50 and 70 Gy or 290 MeV/u carbon ions at a dose of 30 Gy. Potential genes related to radiosensitivity were selected by comparing the expression values before and after irradiation (with both gamma rays and carbon ions) using a filter for at least 1.5-fold changes. Furthermore, candidate genes which had significantly different ratio values between the two tumors (P < 0.05) were detected by unpaired Student\u27s t-tests. Subsequent analysis by quantitative reverse-transcription polymerase chain reaction (RT-PCR) confirmed our microarray data. Protein expression and function were examined by immunohistochemical studies.Results: Four genes, Efna1, Sprr1a, Srgap3 and Xrra1, were selected as potential genes related to radioresistance after gamma and carbon ion irradiation. RT-PCR confirmed that Efna1 was induced in radioresistant NR-S1. Efna1, a proangiogenic factor, was expressed in the cytoplasm of tumor cells and significant increases in microvascular density were observed in the radioresistant NR-S1.Conclusions: We found that Efna1 may be a potential molecule related to radioresistance in murine tumors.The 14th European Cancer Conference, ESTRO26 meeting, European Society for therapeutic radiology and oncolog