CHANGE IN E-CADHERIN EXPRESSION AFTER X-RAY-IRRADIATION OF A HUMAN CANCER CELL-LINE IN-VITRO AND IN-VIVO

Purpose: To investigate changes in E-cadherin expression after X-ray i rradiation of a human cancer cell line lit vitro and in vivo. Methods and Materials: E-cadherin expression on a human squamous cell carcinom a of the thyroid gland (T-SCC cell), which was established in our labo ratory, at 24 h after graded single doses of irradiation and at 7 succ essive times after 10-Gy irradiation were investigated in vitro by imm unoblot analysis with the monoclonal antibody to human E-cadherin, The changes in E-cadherin expression caused by irradiation of T-SCC tumor s that were transplanted into athymic nude mice were also determined i n vivo by immunohistochemical staining and immunoblot analysis in a si milar fashion to that in vitro. Results: In vitro studies revealed tha t E-cadherin expression had increased significantly on T-SCC cells at 24 h after irradiation with doses of 2 to 10 Gy and that, in a time-co urse analysis, the expression had increased significantly at 3 to 72 h after irradiation compared with an unirradiated control cell, althoug h it was not observed at 1 h after irradiation. In in vivo studies, a significant increase in E-cadherin expression was observed at 24 h aft er irradiation with 5 and 10 Gy by immunohistochemical staining and ti me-course studies demonstrated that E-cadherin increased temporarily a t 12 to 24 h after 10-Gy irradiation; however, immunoblot analysis did not show alteration of E-cadherin expression by irradiation. Conclusi on: X-ray irradiation upregulated E-cadherin expression on T-SCC cells in vitro and in vivo. (C) 1998 Elsevier Science Inc.