title: An antisense oligonucleotide targeted to human Ku86 messenger RNA sensitizes M059K malignant glioma cells to ionizing radiation, bleomycin, and etoposide but not DNA cross-linking agents.
abstract: Ku is a heterodimer of M(r) 70,000 and M(r) 86,000 subunits. It binds with strong affinity to DNA ends and is indispensable for nonhomologous DNA end joining (NHEJ) and V(D)J recombination. In this study, we investigated whether down-regulation of the Ku86 gene, by 2'-O-methoxyethyl/uniform phosphorothioate chimeric antisense oligonucleotides (ASOs), increases the sensitivity of the DNA-protein kinase catalytic subunit (PKcs)-proficient human glioma cell line (M059K), and its isogenic DNA-PKcs-deficient counterpart (M059J), to ionizing radiation and anticancer drugs. Transfection of these cell lines with 200 nM Ku86 antisense ASOs was associated with a specific decrease in Ku86 mRNA levels (IC(50) <25 nM; n = 3) and a concomitant rapid decrease (<10% of control) in Ku86 protein expression. Moreover, transfection of M059K cells with Ku86 antisense ASOs markedly increased cell death after treatment with ionizing radiation, bleomycin, and etoposide. However, no sensitization to the DNA cross-linking agents chlorambucil and cisplatin was observed after Ku86 antisense transfection. As expected, transfection of M059J cells with Ku86 antisense ASOs did not result in any sensitization to ionizing radiation, bleomycin, or DNA cross-linking agents, but there was a 2-fold increase in sensitivity to etoposide. Thus, our results indicate that antisense ASOs targeted against Ku86 may increase the efficacy of radiotherapy and DNA-damaging agents in tumor treatment. Furthermore, Ku86 antisense ASOs may be used to create a temporal knockout in different human cell lines to further investigate the biological roles of Ku86.
authors.affiliation: Department of Oncology, Division of Radiation Oncology, Montreal General Hospital, McGill University, Quebec, H3G 1A4 Canada.
authors.forename: Alexandre I
authors.initials: AI
authors.lastname: Belenkov
authors.forename: Jean-Pierre
authors.initials: JP
authors.lastname: Paiement
authors.forename: Lawrence C
authors.initials: LC
authors.lastname: Panasci
authors.forename: Brett P
authors.initials: BP
authors.lastname: Monia
authors.forename: Terry Y K
authors.initials: TY
authors.lastname: Chow
mesh_terms: D034961:Antigens, Nuclear; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001761:Bleomycin / Q000494:pharmacology; D002699:Chlorambucil / Q000494:pharmacology; D002945:Cisplatin / Q000494:pharmacology; D004265:DNA Helicases; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D005047:Etoposide / Q000494:pharmacology; D005910:Glioma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000532:radiotherapy*; D006801:Humans; D007700:Kinetics; D000072200:Ku Autoantigen; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics*; D016376:Oligonucleotides, Antisense / Q000235:genetics* / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D013379:Substrate Specificity; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D034961:Antigens, Nuclear; D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger; D001761:Bleomycin; D002699:Chlorambucil; D005047:Etoposide; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen; D002945:Cisplatin