Journal Article

Delayed Expression of Apoptosis in X-irradiated Human Leukemic MOLT-4 Cells Transfected with Mutant p53

Nakano, Hisako, Yonekawa, Hiromichi, Shinohara, Kunio

2003

Overview

The effects of X-rays on cell survival, apoptosis, and long-term response in the development of cell death as measured by the dye exclusion test were studied in human leukemic MOLT-4 cells (p53 wild-type) stably transfected with a mutant p53 cDNA expression vector. Cell survival, as determined from colony-forming ability, was increased in an expression level dependent manner, but the increase was partial even with the highest-expressing clone (B3). This contrasts with the prior observation that cell death and apoptosis in B3 are completely inhibited at 24 h after irradiation with 1.8 Gy of X-rays1). The examination of B3 cells incubated for longer than 24 h after X-irradiation showed a delay in the induction of cell death and apoptosis. Western blot analysis revealed that the time required to reach the highest level of wild-type p53 protein in B3 was longer than the time in MOLT-4 and that the p53 may be stabilized by the phosphorylation at Ser-15. These results suggest that the introduction of mutant p53 into MOLT-4 merely delays the development of apoptosis, during which the cells could repair the damage induced by X-rays, and results in the partial increase in cell survival.

• Publisher: The Japan Radiation Research Society and Japanese Society for Therapeutic Radiology and Oncology,Oxford University Press
• Subject: Analysis / Apoptosis / Apoptosis - radiation effects / Cell death / Humans / Irradiation / Leukemia / Leukemia, Lymphoid - pathology / Leukemia, Lymphoid - physiopathology / Mutation / Phosphorylation / Survival / Time Factors / Transfection / Tumor Cells, Cultured - radiation effects / Tumor proteins / Tumor Suppressor Protein p53 - genetics / Tumor Suppressor Protein p53 - metabolism / X-rays