Analysis of apoptotic cell death following irradiation in SCC malignant cell lines derived from the head and neck *
To explore radiation-resistancy in head and neek squamous cell carcinoma (HNSCC), two HNSCC lines, KB derived from the oral floor and HEp-2 from the larynx. were used to clarity the cellular biologic alterations related to apoptotic cell death induced by irradiation. Both cell lines revealed ultrastructural apoptotic morphological changes and showed dose- and time -dependent increase in to the apoptotic fraction examined by the TUNEL method using flow cytometry. The KB cells showed time- and dose-dependent upregulation of membrane Fas (mFas) expression after irradiation. Analysis of alteration in the mRNA expression levels of apoptosis-related genes demon strated slight upregulation of Fas. Flice. Bax. and TNFRl genes in KB cells and of the Fas ligand gene in HEp-2 cells In addition, the DcR3 gene. which completes Fas-Fas ligand binding and inhibits Fas-mediated apoptosis. was upregulated in KB cells alter irrudiation. Based on these result. Fas-mediated apoptotic pathway may be involved in irradiation- induced apoptosis. via p53 upregulation. Futher investigations are required to resolve questions regarding the radiation-resistaney which often occurs after radiotherapy for head and neek malignancies. (Accepted on August 10, 2000) Kawasaki Igakkaishi 26 (3) : 147 -154, 2000
