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 irradiation of a human cancer cell line lit vitro and in vivo. Methods and Materials: E-cadherin expression on a human squamous cell carcinoma of the thyroid gland (T-SCC cell), which was established in our laboratory, at 24 h after graded single doses of irradiation and at 7 successive times after 10-Gy irradiation were investigated in vitro by immunoblot analysis with the monoclonal antibody to human E-cadherin, The changes in E-cadherin expression caused by irradiation of T-SCC tumors that were transplanted into athymic nude mice were also determined in vivo by immunohistochemical staining and immunoblot analysis in a similar fashion to that in vitro. Results: In vitro studies revealed that 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-course analysis, the expression had increased significantly at 3 to 72 h after irradiation compared with an unirradiated control cell, although 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 after irradiation with 5 and 10 Gy by immunohistochemical staining and time-course studies demonstrated that E-cadherin increased temporarily at 12 to 24 h after 10-Gy irradiation; however, immunoblot analysis did not show alteration of E-cadherin expression by irradiation. Conclusion: X-ray irradiation upregulated E-cadherin expression on T-SCC cells in vitro and in vivo. (C) 1998 Elsevier Science Inc.