Regrowth and radiation sensitivity of quiescent cells isolated from EMT6/Ro-fed plateau monolayers.
A quiescent [denoted as Q(G0/G1)] subpopulation was isolated from EMT6/Ro-fed plateau monolayers by centrifugal elutriation. The median Coulter volume of these cells was significantly smaller than that of the original population from which they were elutriated. Using two-step acridine orange staining and dual parameter flow cytometric analysis, over 95% of quiescent cells were found to have G1 DNA content, and 80% of the cells had a decreased RNA content as compared to rapidly proliferating exponential G1 cells. After labeling for 24 hr (two doubling times) with [3H]thymidine, less than 2% of the quiescent cells incorporated [3H]thymidine as measured by autoradiography. The colony-forming efficiency of these cells was not significantly different from that of exponential cells. When such Q(G0/G1) cells were replated in fresh medium at a lower density, there was a lag time of 30 hr before any increase in cell number was detected, after which the cell-doubling rate matched that of exponential culture. Results obtained from the radiation dose-response curves showed that quiescent (G0/G1) cells were more radiosensitive than exponential G1 or unseparated fed plateau cells.
D000818:Animals; D002453:Cell Cycle; D002469:Cell Separation; D002470:Cell Survival / Q000528:radiation effects*; D002478:Cells, Cultured; D004273:DNA, Neoplasm / Q000032:analysis; D005260:Female; D005434:Flow Cytometry; D008325:Mammary Neoplasms, Experimental / Q000473:pathology*; D051379:Mice; D012334:RNA, Neoplasm / Q000032:analysis
D004273:DNA, Neoplasm; D012334:RNA, Neoplasm