title: Cell cycle control pathways act as conditioning factors for TK/GCV sensitivity in pancreatic cancer cells.
abstract: The suicide system TK/GCV is an enzyme/prodrug therapy that involves the transfer of the cDNA for the herpes simplex virus thymidine kinase gene (TK) into tumor cells which then sensitizes the cells to the non-toxic antiviral drug ganciclovir. Although extensively characterized, the suicide system TK/GCV conceals the details of its mechanism of action. In order to shed some light on this issue, we conducted experiments designed to identify key features of sensitive cells, as compared to cells that displayed reduced sensitivity to TK/GCV. Cell lines displaying different degrees of sensitivity underwent apoptotic cell death upon treatment with TK/GCV. S-phase delay, however, was almost exclusively restricted to sensitive cells and was impaired in a model of treatment-induced resistance. In this model genes with differential expression associated to induced resistance were identified. Noteworthy, two cell cycle-related genes (CCNE1 and GADD45) were functionally validated as conditioners of cellular sensitivity to TK/GCV. The relevance of cell cycle control was further demonstrated by experiments showing the association of Chk1 activation with greater TK/GCV cytotoxicity. Combination treatment with Chk1 inhibitor UCN-01 induced, in sensitive cells, an antagonistic effect on TK/GCV cytotoxicity highlighting the relevance of Chk1's activity on TK/GCV mechanism of action. These results reveal the relevance of cell cycle control pathways in the cytotoxicity induced by the TK/GCV system identifying candidate genes as conditioners of TK/GCV sensitivity. Moreover it points out, for the first time at Chk1 activation as a key factor to mediate TK/GCV cytotoxicity.
authors.affiliation: Programa Gens i Malaltia, Parc de Recerca Biomèdica de Barcelona, Barcelona, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Abate-Daga
authors.forename: Laura
authors.initials: L
authors.lastname: Garcia-Rodríguez
authors.forename: Lauro
authors.initials: L
authors.lastname: Sumoy
authors.forename: Cristina
authors.initials: C
authors.lastname: Fillat
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D064007:Ataxia Telangiectasia Mutated Proteins; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D019927:Cyclin E / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D015774:Ganciclovir / Q000494:pharmacology*; D020869:Gene Expression Profiling; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D010190:Pancreatic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D013937:Thymidine Kinase / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism; D000097642:GADD45 Proteins
chemical_list: D000998:Antiviral Agents; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D019927:Cyclin E; D004268:DNA-Binding Proteins; D015774:Ganciclovir; D009687:Nuclear Proteins; D015513:Oncogene Proteins; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D013937:Thymidine Kinase; D025521:Tumor Suppressor Proteins; C475820:CCNE1 protein, human; C439070:GADD45A protein, human; D000097642:GADD45 Proteins; C576324:ATM protein, human; C576597:ATR protein, human; C000605867:CHEK1 protein, human; C578634:CHEK2 protein, human