All issues > Volume 46(7); 2003

Original Article

J Korean Pediatr Soc. 2003;46(7):679-686. Published online July 15, 2003.

Apoptotic Pathway Induced by Dominant Negative ATM Gene in CT-26 Colon Cancer Cells

Jung Chang JC Lee¹, Ho Keun HK Yi¹, Sun Young SY Kim¹, Dae Yeol DY Lee¹, Pyoung Han PH Hwang¹, Jin Woo JW Park²

¹Department of Pediatrics, Schoool of Medicine, Chonbuk National University, Jeonju, Korea
²Department of Biochemistry, Schoool of Medicine, Chonbuk National University, Jeonju, Korea

Correspondence Pyoung Han PH Hwang ,Email: hwaph@moak.chonbuk.ac.kr

Abstract

Purpose
: Ataxia telangiectasia mutated(ATM) is involved in DNA damage responses at different cell cycle checkpoints, and signalling pathways associated with regulation of apoptosis in response to ionizing radiation(IR). However, the signaling pathway that underlies IR-induced apoptosis in ATM cells has remained unknown. The purpose of this study was, therefore, to investigate the apoptotic pathway that underlies IR-induced apoptosis in a CT-26 cells expressing dominant negative ATM (DN-ATM).
Methods
: We generated a replication-deficient recombinant adenovirus encoding the DN-ATM(Ad/ DN-ATM) or control adenovirus encoding no transgene(Ad/GFP) and infected adenovirus to CT-26 cells. After infection, we examined apoptosis and apoptotic pathway by [3H]-thymidine assay, DNA fragmentation, and Western immunoblot analysis.
Results
: DN-ATM gene served as the creation of AT phenotype in a CT-26 cells as revealed by decreased cell proliferations following IR. In addition, IR-induced apoptosis was regulated through the reduced levels of the anti-apoptotic protein Bcl-2, the increased levels of the apoptotic protein Bax, and the activation of caspase-9, caspase-3, and PARP.
Conclusion
: These results indicate that the pathway of IR-induced apoptosis in CT-26 cells expressing DN-ATM is mediated by mitochondrial signaling pathway involving the activation of caspase 9, caspase 3, and PARP.

Keywords :Dominant negative ATM, Ionizing radiation, Apoptotic pathway