title: Ectopic expression of herpes simplex virus-thymidine kinase gene in human non-small cell lung cancer cells conferred caspase-activated apoptosis sensitized by ganciclovir.
abstract: Human non-small cell lung cancer (NSCLC) cells were transfected with recombinant prodrug herpes simplex virus type I thymidine kinase (HSV-tk) cDNA, and the selected clones underwent apoptosis in response to induction by antiviral ganciclovir (GCV). The efficiency of GCV-induced growth inhibition and the extent of the bystander effect were associated with the expression level of HSV-TK in stable transfectants. Development in the HSV-tk/GCV system toward cell death was initiated with cell-cycle accumulation at S and G(2)/M phases, immediately followed by the appearance of sub-G(0)/G(1) cells after drug exposure. To investigate the regulation of cell-cycle modulators during drug treatment, we analyzed release of the apoptosis initiator cytochrome c and activation of the downstream effectors caspase-9, caspase-3 and poly(ADP-ribose)polymerase 16 hr after GCV sensitization, followed by transient escalation of tumor-suppressor p53 and cell-cycle modulators cyclin A and B(1) before committing to programmed cell death. Furthermore, tumor regression was proportional to the degree of ectopic expression of the transferred HSV-tk gene. Our results demonstrate that the HSV-tk/GCV system effectively inhibits the proliferation of NSCLC cells in vitro and in vivo through potent induction of apoptosis, thus providing a rationale for further development.
authors.affiliation: Department of Biology, National Taiwan Normal University, Taipei, Taiwan, Republic of China.
authors.forename: Chien-Chih
authors.initials: CC
authors.lastname: Chiu
authors.forename: Yuan-Lin
authors.initials: YL
authors.lastname: Kang
authors.forename: Tsung-Hsiang
authors.initials: TH
authors.lastname: Yang
authors.forename: Chih-Hsin
authors.initials: CH
authors.lastname: Huang
authors.forename: Kang
authors.initials: K
authors.lastname: Fang
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D015153:Blotting, Western; D002289:Carcinoma, Non-Small-Cell Lung / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D020169:Caspases / Q000378:metabolism*; D002453:Cell Cycle; D003574:Cytochrome c Group / Q000378:metabolism; D004273:DNA, Neoplasm / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D005260:Female; D005434:Flow Cytometry; D015774:Ganciclovir / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D016158:Genes, p53 / Q000235:genetics; D005822:Genetic Vectors; D005910:Glioma; D018259:Herpesvirus 1, Human / Q000201:enzymology*; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D051379:Mice; D008819:Mice, Nude; D010957:Plasmids; D012333:RNA, Messenger / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D013937:Thymidine Kinase / Q000235:genetics*; D014162:Transfection; D014407:Tumor Cells, Cultured; D023041:Xenograft Model Antitumor Assays
chemical_list: D000970:Antineoplastic Agents; D003574:Cytochrome c Group; D004273:DNA, Neoplasm; D012333:RNA, Messenger; D013937:Thymidine Kinase; D020169:Caspases; D015774:Ganciclovir