Transitional increase in growth fraction estimated by Ki-67 index after irradiation to human tumor in xenograft.
The cell kinetics of human tumor cells (HSG) in vivo were estimated by Ki-67 index to analyze the biological behavior of quiescent cells after irradiation. The increment of Ki-67 index was dose-dependent up to 15 Gy irradiation. The Ki-67 index of tumor cells increased gradually from 35+/-5.0% before irradiation to 56+/-5.0% at day 5 after single irradiation of 15 Gy. Flow-cytometric study showed that the G1 population was decreased and the G2M population was elevated at day 5 after the irradiation. In fractionated irradiation, the time-course in the change of the Ki-67 index was similar to that of single irradiation. It was likely that tumor cells were recruited into the cell cycle from quiescent phase after irradiation. We consider the Ki-67 index to be a reliable indicator of growth fraction and useful to estimate the cell kinetics of irradiated tumors in vivo. The growth fraction estimated by Ki-67 index during radiotherapy is expected to be useful in predicting tumor response to radiation therapy.
Takahashi
Takeo
T
Department of Radiology, Saitama Medical Center, Saitama Medical School, 1981 Kamodatsujido-cho, Kawagoe, Saitama 350-8550, Japan. taketaka@saitama-med.ac.jp
Nakano
Takashi
T
Oka
Kuniyuki
K
Ando
Koichi
K
D000818:Animals; D002455:Cell Division / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005434:Flow Cytometry; D016193:G1 Phase / Q000528:radiation effects; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D012468:Salivary Gland Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000532:radiotherapy*; D014183:Transplantation, Heterologous
D019394:Ki-67 Antigen