title: Hypoxia-targeted triple suicide gene therapy radiosensitizes human colorectal cancer cells.
abstract: The hypoxic microenvironment, an important feature of human solid tumors but absent in normal tissue, may provide an opportunity for cancer-specific gene therapy. The purpose of the present study was to investigate whether hypoxia-driven triple suicide gene TK/CD/UPRT expression enhances cytotoxicity to ganciclovir (GCV) and 5-fluorocytosine (5-FC), and sensitizes human colorectal cancer to radiation in vitro and in vivo. Stable transfectant of human colorectal HCT8 cells was established which expressed hypoxia-inducible vectors (HRE-TK/eGFP and HRE-CD/UPRT/mDsRed). Hypoxia-induced expression/function of TK, CD and UPRT was verified by western blot analysis, flow cytometry, fluorescent microscopy and cytotoxicity assay of GCV and 5-FC. Significant radiosensitization effects were detected after 5-FC and GCV treatments under hypoxic conditions. In the tumor xenografts, the distribution of TK/eGFP and CD/UPRT/mDsRed expression visualized with fluorescence microscopy was co-localized with the hypoxia marker pimonidazole positive staining cells. Furthermore, administration of 5-FC and GCV in mice in combination with local irradiation resulted in tumor regression, as compared with prodrug or radiation treatments alone. Our data suggest that the hypoxia-inducible TK/GCV+CDUPRT/5-FC triple suicide gene therapy may have the ability to specifically target hypoxic cancer cells and significantly improve the tumor control in combination with radiotherapy.
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Hung Tsung
authors.initials: HT
authors.lastname: Hsiao
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Ligang
authors.initials: L
authors.lastname: Xing
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Xuelong
authors.initials: X
authors.lastname: Deng
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Sun
authors.affiliation: Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: C Clifton
authors.initials: CC
authors.lastname: Ling
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA.
authors.forename: Gloria C
authors.initials: GC
authors.lastname: Li
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D059248:Chemoradiotherapy; D015179:Colorectal Neoplasms / Q000473:pathology / Q000628:therapy*; D005260:Female; D005472:Fluorouracil / Q000494:pharmacology; D015774:Ganciclovir / Q000494:pharmacology; D041722:Genes, Transgenic, Suicide; D015316:Genetic Therapy / Q000379:methods*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D009374:Neoplasms, Experimental; D011838:Radiation-Sensitizing Agents / Q000627:therapeutic use*; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D011838:Radiation-Sensitizing Agents; D015774:Ganciclovir; D005472:Fluorouracil