The influence of irradiation on autophagy process in normal and malignant colorectal epithelia.

AIM The authors assessed the influence of preoperative radiotherapy on autophagy process using a quantitative assessment of LC3 expression on both normal and tumoral colorectal tissues. MATERIALS AND METHODS Normal and malignant tissue samples were taken from 50 patients that underwent surgery for colorectal adenocarcinoma of which 11 received preoperative radiotherapy. Tissue samples were included in paraffin and sections were immunomarked for LC3 expression. LC3 percentage was assessed with dedicated software on 10 randomly selected fields with 40× objective from both normal and malignant tissue samples of each patient. The resulting data were assessed and compared with a statistical apparatus. RESULTS LC3 was overexpressed in tumoral tissue as compared with normal one. The LC3 percentage is different from person to person and the higher it is in normal epithelium, the higher will be in tumoral epithelium of the same person, regardless the irradiation. The LC3 expression levels are decreasing from tumoral non-irradiated epithelia to normal irradiated epithelia. LC3 expression in tumoral cells is granular, with particular perinuclear disposal and often "annular" pattern. CONCLUSIONS The autophagy process has a basal level in the normal tissue, with interindividual variability. The autophagy process proved to be upregulated in the tumoral cells, with a particular morphological expression, namely the presence of cytoplasmic coarse granules disposed in an "annular" pattern. Preoperative radiotherapy is downregulating the autophagy process both in normal and tumoral tissue but to a lesser extent in the latter.