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Induction of Apoptosis and Expression of Apoptosis-related Gene Products in Response to Radiation in Murine Tumors

Other Titles
 방사선에 대한 종양의 반응에서 아포프토시스의 유도와 이에 관련되는 유전자 발현 
 Jinsil Seong  ;  Nancy R. Hunter  ;  Luka Milas 
 Journal of the Korean Society for Therapeutic Radiology and Oncology (대한방사선종양학회지), Vol.15(3) : 187-195, 1997 
Journal Title
 Journal of the Korean Society for Therapeutic Radiology and Oncology (대한방사선종양학회지) 
Issue Date
PURPOSE: To analyze the involvement of apoptosis regulatory genes p53, p21waf1/cip1, bax and bcl-2 in induction of apoptosis by radiation in murine tumors. MATERIALS AND METHODS: The radiation-sensitive ovarian carcinoma OCa-I, and the radiation-resistant hepatocarcinoma HCa-I were used. Tumors, 8 mm in diameter, were irradiated with 25 Gy and at various times after irradiation, ranging from 1 to 48 h, were analyzed histologically for apoptosis and by western blot for alterations in the expression of these genes. The p53 status of the tumors were determined by the polymerase chain reaction-single strand conformation polymorphism assay. RESULTS: Both tumors were positive for wild-type p53. Radiation induced apoptosis in OCa-I but not in HCa-I. Apoptosis developed rapidly, peaked at 2 h after irradiation and returned to almost the background level at 48 h. In OCa-I radiation upregulated the expression of p53, p21waf1/cip1, and the bcl-2/bax ratio was decreased. In HCa-I radiation increased the expression of both p53 and p21waf1/cip1, although the increase of the latter was small. The bcl-2/bax ratio was greatly increased. In general the observed changes occurred within a few hours after irradiation, and either preceded or coincided with development of apoptosis. CONCLUSIONS: The development of apoptosis required upregulation of both p53 and p21waf1/cip1 as well as a decrease in bcl-2/bax ratio. In contrast, an increase in bcl-2/bax ratio prevented apoptosis in the presence of upregulated p53 and p21waf1/cip1. These findings indentified the involvement of multiple oncogenes in apoptosis regulation in vivo and demonstrate the complexity that may be associated with the use of a single oncogene assessment for predicting the outcome of cancer therapy with cytotoxic agents.
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1. College of Medicine (의과대학) > Dept. of Radiation Oncology (방사선종양학교실) > 1. Journal Papers
Yonsei Authors
Seong, Jin Sil(성진실) ORCID logo https://orcid.org/0000-0003-1794-5951
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