Differential induction of apoptosis in x-irradiated L5178Y sublines bearing p53 mutation |
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| Authors: | I Szumiel A Jaworska M Kapiszewska A John I Gr?dzka B Sochanowicz |
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| Institution: | (1) Department of Radiobiology and Health Protection, Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-918 Warsaw, Poland e-mail: izasz@orange.ichtj.waw.pl Tel.: +48-22-8110736, Fax: +48-22-8111532, PL;(2) Radiation Medicine Department, Norwegian Radiation Protection Authority, Oslo, Norway, NO;(3) Department of Biochemistry, University of Al-Ain, United Arab Emirates, AE |
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| Abstract: | We examined apoptosis and expression of p53, E2F-1, bax, bclxL and bcl2 proteins in two L5178Y (LY) murine lymphoma sublines, LY-R and LY-S, which differ in radiosensitivity and double-strand
break (DSB) repair. Both sublines are heterozygous for a p53 mutation in codon 170 that precludes the transactivation function.
Accordingly, there is no G1/S arrest after irradiation.We found that there is no change in expression of E2F-1, bax, bclxL or bcl2 proteins in both LY sublines after x-irradiation. LY-R cells do not constitutively express bcl2, whereas both sublines
show high bax content. Radiation induces delayed apoptosis to a greater extent in LY-S than in LY-R cells. The apoptosis can
be seen 24 h after irradiation (2 Gy) of LY-S cells, with a maximum at 48 h. LY-R cells need 5 Gy and 72 h post-irradiation
incubation to show marked apoptosis (identified by the TUNEL method). The reported observations support the assumption that
differential radiosensitivity of LY sublines is associated with the induction of apoptosis that is not related to transactivation
by p53 and is primarily related to differential DNA repair ability.
Received: 19 August 1999 / Accepted in revised form: 30 November 1999 |
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| Keywords: | L5178Y sublines Differential radiosensitivity Post-irradiation expression of BAX BCL2 BCLXL Mutated p53 Post-irradiation apoptosis |
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