The role of Bcl-X(S) in radiation sensitivity.
Bcl-X(S) is a pro-apoptosis member of the Bcl2 family that has been shown to induce cell death and enhance chemosensitivity. We have investigated the effect of Bcl-X(S) overexpression on radiation sensitivity. Using a tetracycline-repressible system, we found that removal of tetracycline for 16 h induced Bcl-X(S) and reduced the surviving fraction of NIH 3T3 cells to 25%. However, radiation sensitivity was not significantly affected by Bcl-X(S) expression; the mean inactivation doses for Bcl-X(S) repressed and Bcl-X(S) induced cells were 2.7 +/- 0.3 and 2.3 +/- 0.1 Gy, respectively. We conclude that Bcl-X(S) induces cell death without affecting radiation sensitivity. These results suggest that mitochondrial pathways to apoptosis may not have a significant role in survival after irradiation.
Morgan
M A
MA
Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan 49109, USA.
Poynter
J N
JN
Maybaum
J
J
Lawrence
T S
TS
D016475:3T3 Cells; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects*; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D051379:Mice; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D011829:Radiation Dosage; D011836:Radiation Tolerance / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects*; D013752:Tetracycline / Q000494:pharmacology; D051020:bcl-X Protein
C494812:Bcl2l1 protein, mouse; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; D013752:Tetracycline