title: Oncolytic viruses and DNA-repair machinery: overcoming chemoresistance of gliomas.
abstract: The current standard of care for malignant gliomas is surgical resection and radiotherapy followed by extended adjuvant treatment with the alkylating agent temozolomide. Temozolomide causes DNA damage, which induces cell death. Through changes in the DNA-repair machinery, glioma cells develop resistance to temozolomide, compromising the therapeutic effect of the drug. Oncolytic viruses, such as herpes simplex viruses and adenoviruses, are being introduced into clinical trials as a new treatment for this malignancy. Biological studies have revealed that these viruses use mechanisms to either inactivate (adenovirus) or take advantage of (herpes simplex virus) the cellular DNA-repair machinery to achieve productive replication. Adenoviruses express proteins from the early genes to either downregulate the damage-repair enzyme, O(6)-methylguanine-DNA methyltransferase, or degrade poly (ADP-ribose) polymerase or the Mre11-Rad50-NBS1 complex, which detects DNA strand breaks. Temozolomide enhances herpes simplex virus oncolysis by upregulating the DNA repair-related genes growth arrest DNA damage 34 and ribonucleotide reductase. The interactions between viruses and the DNA-repair machinery suggest that a combined temozolomide and viral therapy will overcome the limitations of a single therapy by diminishing chemoresistance or enhancing oncolysis. This hypothesis has been supported by promising findings from preclinical and clinical studies.
authors.affiliation: University of Texas MD Anderson Cancer Center, Department of Neuro-Oncology, 1515 Holcombe Blvd., Box 1002, Houston, TX 77030, USA. hjiang@mdanderson.org
authors.forename: Hong
authors.initials: H
authors.lastname: Jiang
authors.forename: Marta M
authors.initials: MM
authors.lastname: Alonso
authors.forename: Candelaria
authors.initials: C
authors.lastname: Gomez-Manzano
authors.forename: Yuji
authors.initials: Y
authors.lastname: Piao
authors.forename: Juan
authors.initials: J
authors.lastname: Fueyo
mesh_terms: D018906:Antineoplastic Agents, Alkylating / Q000627:therapeutic use*; D001932:Brain Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000821:virology*; D004249:DNA Damage; D004260:DNA Repair; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D019008:Drug Resistance, Neoplasm; D005910:Glioma / Q000188:drug therapy* / Q000235:genetics / Q000821:virology*; D006564:Herpesviridae; D006801:Humans; D050130:Oncolytic Virotherapy / Q000379:methods*; D050504:Oncolytic Viruses / Q000235:genetics / Q000302:isolation & purification*; D000077204:Temozolomide
chemical_list: D018906:Antineoplastic Agents, Alkylating; D003606:Dacarbazine; D000077204:Temozolomide