Enhanced efficacy of radiation-induced gene therapy in mice bearing lung adenocarcinoma xenografts using hypoxia responsive elements.
The aim of the present study was to investigate whether the hypoxia responsive element (HRE) could be used to enhance suicide gene (HSV-tk) expression and tumoricidal activity in radiation-controlled gene therapy of human lung adenocarcinoma xenografts. A chimeric promoter, HRE-Egr, was generated by directly linking a 0.3-kb fragment of HRE to a 0.6-kb human Egr-1 promoter. Retroviral vectors containing luciferase or the HSV-tk gene driven by Egr-1 or HRE-Egr were constructed. A human adenocarcinoma cell line (A549) was stably transfected with the above vectors using the lipofectamine method. The sensitivity of transfected cells to prodrug ganciclovir (GCV) and cell survival rates were analyzed after exposure to a dose of 2 Gy radiation and hypoxia (1%). In vivo, tumor xenografts in BALB/c mice were transfected with the constructed retroviruses and irradiated to a total dose of 6 Gy, followed by GCV treatment (20 mg/kg for 14 days). When the HSV-tk gene controlled by the HRE-Egr promoter was introduced into A549 cells by a retroviral vector, the exposure to 1% O(2) and 2 Gy radiation induced significant enhancement of GCV cytotoxicity to the cells. Moreover, in nude mice bearing solid tumor xenografts, only the tumors infected with the hybrid promoter-containing virus gradually disappeared after GCV administration and radiation. These results indicate that HRE can enhance transgene expression and tumoricidal activity in HSV-tk gene therapy controlled by ionizing radiation in hypoxic human lung adenocarcinoma.
Wang
Wei-Dong
WD
Department of Oncology, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China. wwdir@yahoo.com
Chen
Zheng-Tang
ZT
Li
Rong
R
Li
De-Zhi
DZ
Duan
Yu-Zhong
YZ
Cao
Zheng-Huai
ZH
D000230:Adenocarcinoma / Q000188:drug therapy / Q000235:genetics / Q000532:radiotherapy*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D015687:Cell Hypoxia / Q000528:radiation effects*; D015774:Ganciclovir / Q000627:therapeutic use; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000532:radiotherapy*; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D010101:Oxygen Consumption; D011879:Radiotherapy Dosage; D012190:Retroviridae / Q000528:radiation effects; D014162:Transfection; D014183:Transplantation, Heterologous
D015774:Ganciclovir