EFFECT OF RADIATION ON THE EXPRESSION OF E-CADHERIN AND ALPHA-CATENINAND INVASIVE CAPACITY IN HUMAN LUNG-CANCER CELL-LINE IN-VITRO

Purpose: To investigate the effect of radiation on E-cadherin and alph a-catenin expression in a human lung cancer cell line, and also evalua te invasive capacity in the membrane invasion culture system using the Boyden Chamber. Materials and Methods: The immunoblot and immunofluor escence analyses were performed using the human lung cancer cell line A549 to examine altered expression of E-cadherin and alpha-catenin aft er irradiation. We also compared invasive capacity of untreated cells with that of irradiated cells. Results: Immunoblot analysis revealed t hat the expression of E-cadherin increased after irradiation. In a tim e-course analysis, the expression was increased 6 h after irradiation with 10 Gy and reached its peak level at 24 h, being 2.3 times the con trol value, whereas expression at 1 and 3 h after irradiation was almo st equivalent to that of the control. A slight increase in expression was observed after irradiation of 2 Gy and the expression reached peak levels after 5 Gy, After fractionated irradiation, the increase in ex pression of both E-cadherin and alpha-catenin was observed, and the al teration of alpha-catenin was more prominent than that after a single irradiation of the same total dose. In the immunofluorescence study fo r E-cadherin antibody analyzed by confocal laser scanning microscopy, increased intensity in irradiated cells produced as a nondisrupted and continuous line at cell-cell contact sites. In an invasive assay, the number of migrated cells in irradiated cells after a dose of 5 and 10 Gy was reduced significantly compared to untreated cells. Conclusion: The results indicate that irradiation of A549 increased the expressio n of E-cadherin, possibly preserving their functional property. (C) 19 98 Elsevier Science Inc.