title: Adenovirus E1a protein enhances the cytotoxic effects of the herpes thymidine kinase-ganciclovir system.
abstract: Cancer gene therapy based on the use of suicide genes, such as the thymidine kinase gene, is not producing satisfactory results. Several approaches have been delineated to enhance the therapeutic responses, including augmentation of the bystander effect, the combination of the herpes simplex virus thymidine kinase-ganciclovir (HSVTK-GCV) system into replication competent adenoviruses and others. Moreover, because usually less than 20% of human malignant cells are in S-phase, the HSVTK-GCV system is not as efficient as expected. To increase the cytotoxic effects of the HSVTK-GCV system, we hypothesized that concomitant expression of E1a protein, which drives cells to proliferation and S-phase, could increase the effects of the HSVTK-GCV system. Several retroviruses were constructed carrying bicistronic sequences of TK and E1a 12S genes under the control of the CMV promoter. The constructions were tested in murine (NIH-3T3, MSC11A5) and human cells (IMR90, HeLa, MDA-MB435). A clear increase of the HSVTK-GCV system killing effect in nonconfluent cells was observed in the cells studied, especially in NIH-3T3, MSC11A5, IMR90, and MDA-MB435 expressing cells. In confluence, the NIH3T3 and IMR90 E1a-TK-expressing cells were also very sensitive and most malignant E1a-TK-expressing cells showed an irreversible G2-M cell cycle arrest. Moreover, the concomitant expression of adenovirus E1a and the HSVTK-GCV system increased the sensitivity to anticancer agents such as cisplatin. These results show that adenovirus E1a protein expression clearly enhances the cytotoxic effects of the HSVTK-GCV system and the response to treatment with cisplatin.
authors.affiliation: Department of Pathology, Clínica Puerta de Hierro, Madrid, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Parada
authors.forename: Javier
authors.initials: J
authors.lastname: Hernández Losa
authors.forename: Juan
authors.initials: J
authors.lastname: Guinea
authors.forename: Víctor
authors.initials: V
authors.lastname: Sánchez-Arévalo
authors.forename: Víctor
authors.initials: V
authors.lastname: Fernández Soria
authors.forename: Luis
authors.initials: L
authors.lastname: Alvarez-Vallina
authors.forename: Ricardo
authors.initials: R
authors.lastname: Sánchez-Prieto
authors.forename: Santiago
authors.initials: S
authors.lastname: Ramón y Cajal
mesh_terms: D016475:3T3 Cells / Q000187:drug effects / Q000473:pathology; D017500:Adenovirus E1A Proteins / Q000235:genetics / Q000494:pharmacology*; D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D002453:Cell Cycle / Q000235:genetics; D002945:Cisplatin / Q000494:pharmacology; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1; D004357:Drug Synergism; D015774:Ganciclovir / Q000494:pharmacology*; D005818:Genetic Engineering / Q000379:methods; D015316:Genetic Therapy / Q000379:methods*; D006367:HeLa Cells / Q000187:drug effects / Q000473:pathology; D006801:Humans; D051379:Mice; D012190:Retroviridae / Q000235:genetics; D018139:Simplexvirus / Q000201:enzymology* / Q000235:genetics; D013937:Thymidine Kinase / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D017500:Adenovirus E1A Proteins; D000903:Antibiotics, Antineoplastic; C534699:CCNB1 protein, human; C534700:Ccnb1 protein, mouse; D019926:Cyclin B; D056744:Cyclin B1; D013937:Thymidine Kinase; D015774:Ganciclovir; D002945:Cisplatin