title: Variation in radiation sensitivity during the cell cycle of two human squamous cell carcinomas.
abstract: Changes in the radiation age response are described in two cell lines derived from human squamous cell carcinomas. A radioresistant tumor cell line, JSQ-3, has a DO of 240 cGy and is polyploid with a DNA content of 2.68. A relatively radiosensitive tumor cell line, SCC-61, has a DO of 126 cGy and has a DNA index of 1.16. Tumor cells were separated and synchronized by centrifugal elutriation; flow cytometry was used to determine cell-cycle parameters and relative synchrony. The radioresistant cell line, JSQ-3B, was found to have twice the number of cells in S-phase than the more sensitive cell line (28% and 13% for JSQ-3B and SCC-61B, respectively). Both cell lines, despite differences in intrinsic radiosensitivity, were most resistant during S-phase (DOs of 258 and 157 cGy for JSQ-3B and SCC-61B, respectively) and were maximally sensitive during G1 (DOs of 193 and 95 cGy for JSQ-3B and SCC-61B, respectively). Clinical implications of our findings are discussed.
authors.affiliation: Department of Radiation and Cellular Oncology, Michael Reese Medical Center, Chicago, IL.
authors.forename: C A
authors.initials: CA
authors.lastname: Quiet
authors.forename: R R
authors.initials: RR
authors.lastname: Weichselbaum
authors.forename: D J
authors.initials: DJ
authors.lastname: Grdina
mesh_terms: D002294:Carcinoma, Squamous Cell; D002453:Cell Cycle / Q000528:radiation effects*; D002455:Cell Division / Q000528:radiation effects; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D004305:Dose-Response Relationship, Drug; D006258:Head and Neck Neoplasms; D006801:Humans; D014410:Tumor Stem Cell Assay