title: Characterization of radiation sensitivity of human squamous carcinoma A431 cells.
abstract: Studies have been performed to investigate the radiosensitivity of human squamous carcinoma cells. A431 cells were grown in vitro as exponential and fed-plateau monolayer cultures or as multicellular spheroids. Radiobiological studies of various cultures showed that fed-plateau phase cells were more sensitive (D0 = 1.3 Gy) than exponentially growing cells (D0 = 1.5 Gy). After a single dose of 12 Gy or two doses of 6 Gy irradiation, A431 cultures exhibited a large capacity for potentially lethal damage (PLD) repair (PLD repair factor = 17), but a relatively small sublethal damage (SLD) repair. In order to measure the radiation sensitivity of proliferating (P) and quiescent (Q) cells, enriched populations of P- and Q-cells were isolated from A431 spheroids. Flow cytometric analysis with acridine orange (AO) staining demonstrated that there was a shift of the RNA histograms in fed-plateau and spheroid cultures towards lower values, suggesting the presence of a subpopulation of Q-cells. Centrifugal elutriation was used to isolate the Q-cells from dissociated spheroid cells. Coulter cell volume distributions and flow cytometric analysis showed that Q-cells had a small cell volume (approximately 1380 microns3), low RNA content and a G1-like DNA content. Continuous labelling experiments with tritiated thymidine confirmed the non-proliferating nature of the Q-cells. Irradiation of the Q-cells after isolation from spheroids with between 0 to 10 Gy showed that they were more radiosensitive (decreased D0) than the P-cells isolated from these spheroids. The latter were, however, similar in radiosensitivity to exponential G1 cells.
authors: Cancer Center, University of Rochester, New York 14642.
authors: C E
authors: CE
authors: Ng
authors: P C
authors: PC
authors: Keng
authors: R M
authors: RM
authors: Sutherland
mesh_terms: D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy*; D002452:Cell Count; D002460:Cell Line; D002469:Cell Separation; D002470:Cell Survival / Q000528:radiation effects; D004273:DNA, Neoplasm / Q000032:analysis; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008938:Mitosis; D012334:RNA, Neoplasm / Q000032:analysis; D011836:Radiation Tolerance
chemical_list: D004273:DNA, Neoplasm; D012334:RNA, Neoplasm