title: Suppression of colorectal tumor growth by regulated survivin targeting.
abstract: A major goal in cancer gene therapy is to develop efficient gene transfer protocols that allow tissue-specific and tightly regulated expression of therapeutic genes. The ideal vector should efficiently transduce cancer cells with minimal toxicity on normal tissues and persistently express foreign genes. One of the most promising regulatory systems is the mifepristone/RU486-regulated system, which has much lower basal transcriptional activity and high inducibility. In this work, we modified this system by incorporating a cancer-specific promoter, the human telomerase reverse transcriptase (hTERT) promoter. By utilizing hTERT promoter to control the regulator, RU486 could specifically induce the expression of foreign genes in cancer cells but not in normal cells. In the context of this system, a dominant negative mutant of survivin (surDN) was controllably expressed in colorectal tumor cells. The surDN expression induced by RU486 showed a dosage- and time-dependent pattern. Regulated expression of surDN caused caspase-dependent apoptosis in colorectal tumor cells but had little effect on normal cells. Analysis of cell viability showed that RU486-induced expression of surDN suppressed colorectal tumor cell growth and had synergic effect in combination with chemotherapeutic agents. The potential of this system in cancer therapy was evaluated in experimental animals. Tumor xenograft models were established in nude mice with colorectal tumor cells, and RU486 was intraperitoneally administered. The results showed that conditional expression of surDN efficiently inhibited tumor growth in vivo and prolonged the life of tumor-burdened mice. Synergized with the chemotherapeutic drug cisplatin, regulated surDN expression completely suppressed tumor growth. These results indicated that this modified RU486-regulated system could be useful in cancer-targeting therapy.
authors.affiliation: Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai 200031, China.
authors.forename: Binghua
authors.initials: B
authors.lastname: Li
authors.forename: Junkai
authors.initials: J
authors.lastname: Fan
authors.forename: Xinran
authors.initials: X
authors.lastname: Liu
authors.forename: Rong
authors.initials: R
authors.lastname: Qi
authors.forename: Linan
authors.initials: L
authors.lastname: Bo
authors.forename: Jinfa
authors.initials: J
authors.lastname: Gu
authors.forename: Cheng
authors.initials: C
authors.lastname: Qian
authors.forename: Xinyuan
authors.initials: X
authors.lastname: Liu
mesh_terms: D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000627:therapeutic use; D017209:Apoptosis; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002945:Cisplatin / Q000627:therapeutic use; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D004305:Dose-Response Relationship, Drug; D004359:Drug Therapy, Combination; D005472:Fluorouracil / Q000627:therapeutic use; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D018014:Gene Transfer Techniques; D005799:Genes, Dominant; D017930:Genes, Reporter; D006367:HeLa Cells; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008869:Microtubule-Associated Proteins / Q000378:metabolism / Q000502:physiology*; D015735:Mifepristone / Q000627:therapeutic use*; D009363:Neoplasm Proteins / Q000378:metabolism / Q000502:physiology*; D011401:Promoter Regions, Genetic; D011897:Random Allocation; D000077022:Survivin; D019098:Telomerase / Q000235:genetics* / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
chemical_list: D000964:Antimetabolites, Antineoplastic; D000970:Antineoplastic Agents; C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D000077022:Survivin; D015735:Mifepristone; D008156:Luciferases; C509186:TERT protein, human; D019098:Telomerase; D020169:Caspases; D002945:Cisplatin; D005472:Fluorouracil