Absence of radiation-induced G1 arrest in two closely related human lymphoblast cell lines that differ in p53 status

J. B. Little, H. Nagasawa, P. C. Keng, Yongjia Yu, C. Y. Li

Research output: Contribution to journalArticle

134 Citations (Scopus)

Abstract

In order to examine more precisely the role of p53 in the activation of the G1/S checkpoint by ionizing radiation, we examined two human lymphoblast cell lines derived from the same donor. The TK6 line had a doubling time of 12.2 h and expressed wild type p53, while the WTK1 line had a doubling time of 12.7 h and expressed mutant p53. The two lines differ significantly in their susceptibility to radiation-induced cell killing and apoptosis. Cells were examined by flow cytometry at regular intervals from 0 to 12 h after irradiation with two different doses designed to yield equivalent survival levels in both cell lines. In some experiments, cells were incubated with colcemid to block them in the first postirradiation mitosis and prevent contamination of the flow cytometric profiles with second cycle cells. There was no significant difference between the two cell lines in the progression of irradiated cells out of G1 and into the S and G2 phases of the cell cycle. In particular, there was no evidence for a prolonged arrest in G1 in the TK6 cell line expressing wild type p53. Furthermore, expression of the p53 downstream genes WAF1/CIP1 and RB appeared normal in TK6 cells. These results suggest that factors other than those in the p53 signal transduction pathway alone may be required to activate the G1/S checkpoint in irradiated human cells and that apoptosis and G1 arrest may utilize different pathways.

Original languageEnglish (US)
Pages (from-to)11033-11036
Number of pages4
JournalJournal of Biological Chemistry
Volume270
Issue number19
DOIs
StatePublished - 1995
Externally publishedYes

Fingerprint

Cells
Radiation
Cell Line
Cell Cycle
Demecolcine
Apoptosis
G2 Phase
p53 Genes
Ionizing Radiation
S Phase
Mitosis
Signal transduction
Flow cytometry
Signal Transduction
Ionizing radiation
Flow Cytometry
Dosimetry
Contamination
Survival
Genes

ASJC Scopus subject areas

  • Biochemistry

Cite this

Absence of radiation-induced G1 arrest in two closely related human lymphoblast cell lines that differ in p53 status. / Little, J. B.; Nagasawa, H.; Keng, P. C.; Yu, Yongjia; Li, C. Y.

In: Journal of Biological Chemistry, Vol. 270, No. 19, 1995, p. 11033-11036.

Research output: Contribution to journalArticle

@article{5c486f5a14d2454cbb5046eafaf5e079,
title = "Absence of radiation-induced G1 arrest in two closely related human lymphoblast cell lines that differ in p53 status",
abstract = "In order to examine more precisely the role of p53 in the activation of the G1/S checkpoint by ionizing radiation, we examined two human lymphoblast cell lines derived from the same donor. The TK6 line had a doubling time of 12.2 h and expressed wild type p53, while the WTK1 line had a doubling time of 12.7 h and expressed mutant p53. The two lines differ significantly in their susceptibility to radiation-induced cell killing and apoptosis. Cells were examined by flow cytometry at regular intervals from 0 to 12 h after irradiation with two different doses designed to yield equivalent survival levels in both cell lines. In some experiments, cells were incubated with colcemid to block them in the first postirradiation mitosis and prevent contamination of the flow cytometric profiles with second cycle cells. There was no significant difference between the two cell lines in the progression of irradiated cells out of G1 and into the S and G2 phases of the cell cycle. In particular, there was no evidence for a prolonged arrest in G1 in the TK6 cell line expressing wild type p53. Furthermore, expression of the p53 downstream genes WAF1/CIP1 and RB appeared normal in TK6 cells. These results suggest that factors other than those in the p53 signal transduction pathway alone may be required to activate the G1/S checkpoint in irradiated human cells and that apoptosis and G1 arrest may utilize different pathways.",
author = "Little, {J. B.} and H. Nagasawa and Keng, {P. C.} and Yongjia Yu and Li, {C. Y.}",
year = "1995",
doi = "10.1074/jbc.270.19.11033",
language = "English (US)",
volume = "270",
pages = "11033--11036",
journal = "Journal of Biological Chemistry",
issn = "0021-9258",
publisher = "American Society for Biochemistry and Molecular Biology Inc.",
number = "19",

}

TY - JOUR

T1 - Absence of radiation-induced G1 arrest in two closely related human lymphoblast cell lines that differ in p53 status

AU - Little, J. B.

AU - Nagasawa, H.

AU - Keng, P. C.

AU - Yu, Yongjia

AU - Li, C. Y.

PY - 1995

Y1 - 1995

N2 - In order to examine more precisely the role of p53 in the activation of the G1/S checkpoint by ionizing radiation, we examined two human lymphoblast cell lines derived from the same donor. The TK6 line had a doubling time of 12.2 h and expressed wild type p53, while the WTK1 line had a doubling time of 12.7 h and expressed mutant p53. The two lines differ significantly in their susceptibility to radiation-induced cell killing and apoptosis. Cells were examined by flow cytometry at regular intervals from 0 to 12 h after irradiation with two different doses designed to yield equivalent survival levels in both cell lines. In some experiments, cells were incubated with colcemid to block them in the first postirradiation mitosis and prevent contamination of the flow cytometric profiles with second cycle cells. There was no significant difference between the two cell lines in the progression of irradiated cells out of G1 and into the S and G2 phases of the cell cycle. In particular, there was no evidence for a prolonged arrest in G1 in the TK6 cell line expressing wild type p53. Furthermore, expression of the p53 downstream genes WAF1/CIP1 and RB appeared normal in TK6 cells. These results suggest that factors other than those in the p53 signal transduction pathway alone may be required to activate the G1/S checkpoint in irradiated human cells and that apoptosis and G1 arrest may utilize different pathways.

AB - In order to examine more precisely the role of p53 in the activation of the G1/S checkpoint by ionizing radiation, we examined two human lymphoblast cell lines derived from the same donor. The TK6 line had a doubling time of 12.2 h and expressed wild type p53, while the WTK1 line had a doubling time of 12.7 h and expressed mutant p53. The two lines differ significantly in their susceptibility to radiation-induced cell killing and apoptosis. Cells were examined by flow cytometry at regular intervals from 0 to 12 h after irradiation with two different doses designed to yield equivalent survival levels in both cell lines. In some experiments, cells were incubated with colcemid to block them in the first postirradiation mitosis and prevent contamination of the flow cytometric profiles with second cycle cells. There was no significant difference between the two cell lines in the progression of irradiated cells out of G1 and into the S and G2 phases of the cell cycle. In particular, there was no evidence for a prolonged arrest in G1 in the TK6 cell line expressing wild type p53. Furthermore, expression of the p53 downstream genes WAF1/CIP1 and RB appeared normal in TK6 cells. These results suggest that factors other than those in the p53 signal transduction pathway alone may be required to activate the G1/S checkpoint in irradiated human cells and that apoptosis and G1 arrest may utilize different pathways.

UR - http://www.scopus.com/inward/record.url?scp=0028990145&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0028990145&partnerID=8YFLogxK

U2 - 10.1074/jbc.270.19.11033

DO - 10.1074/jbc.270.19.11033

M3 - Article

C2 - 7744731

AN - SCOPUS:0028990145

VL - 270

SP - 11033

EP - 11036

JO - Journal of Biological Chemistry

JF - Journal of Biological Chemistry

SN - 0021-9258

IS - 19

ER -