BACKGROUND: Cytochrome p450 isozyme CYP4B1 converts the inert prodrug 4-ipomeanol (4-IM) into toxic alkylating metabolites. Induction of cytotoxicity by 4-IM combined with ionizing radiation (IR) in cells transfected with a fusion protein of rabbit cytochrome CYP4B1 under control of the radiation inducible EGR1 promoter was investigated. The capability of activated 4-IM to sensitize cells to IR was also assessed. MATERIALS AND METHODS: Survival fractions of cells, determined by MTT assays, stably transfected with EGR1-CYP4B1 were compared with that of cells transfected with a control plasmid after IR followed by 4-IM. Radiosensitization was tested by comparing clonogenic survival curves of cells transfected with the CYP4B1 cassette under a CMV promoter instead of EGR-1, irradiated with or without 4-IM. RESULTS: MTT assays for cytotoxicity indicated a decrease in relative survival fractions (survival with 4-IM/survival without 4-IM) of the EGR1-CYP4B1 transfected cells with increasing radiation dosage, but not of control cells. Clonogenic assays revealed decreased survival fractions with increasing radiation doses (CYP4B1 transfected and control cells) and 4-IM concentrations (CYP4B1 transfected cells), but showed no significant differences in slope of survival curves with 4-IM. CONCLUSION: The results indicate IR potentiates the cytotoxic activity of the EGR1-CYP4B1/4-IM transgene system, but activated 4-IM does not sensitize cells to IR. Thus, the EGR1-CYP4B1/4-IM system is a viable radiation-gene therapy system that may allow for improved spatial and temporal control of cytotoxicity by therapeutic radiation fields.
BACKGROUND: Cytochrome p450 isozyme CYP4B1 converts the inert prodrug 4-ipomeanol (4-IM) into toxic alkylating metabolites. Induction of cytotoxicity by 4-IM combined with ionizing radiation (IR) in cells transfected with a fusion protein of rabbit cytochrome CYP4B1 under control of the radiation inducible EGR1 promoter was investigated. The capability of activated 4-IM to sensitize cells to IR was also assessed. MATERIALS AND METHODS: Survival fractions of cells, determined by MTT assays, stably transfected with EGR1-CYP4B1 were compared with that of cells transfected with a control plasmid after IR followed by 4-IM. Radiosensitization was tested by comparing clonogenic survival curves of cells transfected with the CYP4B1 cassette under a CMV promoter instead of EGR-1, irradiated with or without 4-IM. RESULTS:MTT assays for cytotoxicity indicated a decrease in relative survival fractions (survival with 4-IM/survival without 4-IM) of the EGR1-CYP4B1 transfected cells with increasing radiation dosage, but not of control cells. Clonogenic assays revealed decreased survival fractions with increasing radiation doses (CYP4B1 transfected and control cells) and 4-IM concentrations (CYP4B1 transfected cells), but showed no significant differences in slope of survival curves with 4-IM. CONCLUSION: The results indicate IR potentiates the cytotoxic activity of the EGR1-CYP4B1/4-IM transgene system, but activated 4-IM does not sensitize cells to IR. Thus, the EGR1-CYP4B1/4-IM system is a viable radiation-gene therapy system that may allow for improved spatial and temporal control of cytotoxicity by therapeutic radiation fields.
Authors: Hai B Zhou; Yi F Yin; Yan Hu; Xin Li; Li Y Zou; Yong J Li; Yu Gu; Bao Q Ou; Juan Fu; Jun H Du; Gang Wu Journal: Jpn J Radiol Date: 2011-09-29 Impact factor: 2.374
Authors: Aaron M Teitelbaum; Matthew G McDonald; John P Kowalski; Oliver T Parkinson; Michele Scian; Dale Whittington; Katharina Roellecke; Helmut Hanenberg; Constanze Wiek; Allan E Rettie Journal: J Pharmacol Exp Ther Date: 2018-11-08 Impact factor: 4.030
Authors: Su Jin Jang; Joo Hyun Kang; Tae Sup Lee; Sung Joo Kim; Kwang Il Kim; Yong Jin Lee; Gi Jeong Cheon; Chang Woon Choi; Sang Moo Lim Journal: Nucl Med Mol Imaging Date: 2010-08-07