ABSTRACT
PURPOSE: Radiation-induced pulmonary fibrosis (RIF) is a significant complication of radiotherapy for lung cancer. Despite the large number of studies, the molecular mechanisms of RIF are poorly understood. Therefore, the complex protein expression pattern in RIF was characterized by identifying the proteins with an altered expression level after thorax irradiation using two-dimensional electrophoresis (2-DE) and mass spectrometry. MATERIALS AND METHODS: A mouse model of RIF was used to examine the alteration of the lung proteome because of availability of murine data related to human cases and the abundance of murine fibrotic lung samples. A mouse model of RIF was induced in radiosensitive C57BL/6 mice. Twenty-one weeks after 25 Gy irradiation, hematoxylin-eosin staining and hydroxyproline assay confirmed the early-phase pulmonary fibrosis. RESULTS: Lung samples from the irradiated and age-matched control mice were used to generate 16 high quality 2-DE gels containing approximately 1,000 spots. Of the 31 significantly up- or down-regulated protein spots, 17 were identified by MALDI-TOF/MS. CONCLUSIONS: Two important upregulated proteins were found, the alpha-protease inhibitor and galectin-1, which might be used as potential markers for the early phase of RIF.