title: IFN-beta sensitizes neuroblastoma to the antitumor activity of temozolomide by modulating O6-methylguanine DNA methyltransferase expression.
abstract: Although temozolomide has shown clinical activity against neuroblastoma, this activity is likely limited by the DNA repair enzyme O6-methylguanine DNA methyltransferase (MGMT). We hypothesized that IFN-beta could sensitize neuroblastoma cells to the cytotoxic effects of temozolomide through its ability to down-regulate MGMT expression. In vitro proliferation of three neuroblastoma cell lines treated with IFN-beta and temozolomide alone or in combination was examined. Antitumor activity was assessed in both localized and disseminated neuroblastoma xenografts using single-agent and combination therapy, with continuous delivery of IFN-beta being established by a liver-targeted adeno-associated virus-mediated approach. Two neuroblastoma cell lines (NB-1691 and SK-N-AS) were found to have high baseline levels of MGMT expression, whereas a third cell line (CHLA-255) had low levels. Temozolomide had little effect on in vitro proliferation of the neuroblastoma cell lines with high MGMT expression, but pretreatment with IFN-beta significantly decreased MGMT expression and cell counts (NB-1691: 36 +/- 3% of control, P = 0.0008; SK-N-AS: 54 +/- 7% control, P = 0.003). In vivo, NB-1691 tumors in CB17-SCID mice treated with the combination of IFN-beta and temozolomide had lower MGMT expression and a significantly reduced tumor burden, both localized [percent initial tumor volume: 2,516 +/- 680% (control) versus 1,272 +/- 330% (temozolomide), P = 0.01; 1,348 +/- 220%, P = 0.03 (IFN-beta); 352 +/- 110%, P = 0.0001 (combo)] and disseminated [bioluminescent signal: control (1.32e10 +/- 6.5e9) versus IFN-beta (2.78e8 +/- 3.09e8), P = 0.025, versus temozolomide (2.06e9 +/- 1.55e9), P = 0.1, versus combination (2.13e7 +/- 7.67e6), P = 0.009]. IFN-beta appears to sensitize neuroblastoma cells to the cytotoxic effects of temozolomide through attenuation of MGMT expression. Thus, IFN-beta and temozolomide may be a useful combination for treating children with this difficult disease.
authors.affiliation: Department of Surgery, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
authors.forename: Shannon F
authors.initials: SF
authors.lastname: Rosati
authors.forename: Regan F
authors.initials: RF
authors.lastname: Williams
authors.forename: Lindsey C
authors.initials: LC
authors.lastname: Nunnally
authors.forename: Mackenzie C
authors.initials: MC
authors.lastname: McGee
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Sims
authors.forename: Lorraine
authors.initials: L
authors.lastname: Tracey
authors.forename: Junfang
authors.initials: J
authors.lastname: Zhou
authors.forename: Meiyun
authors.initials: M
authors.lastname: Fan
authors.forename: Catherine Y
authors.initials: CY
authors.lastname: Ng
authors.forename: Amit C
authors.initials: AC
authors.lastname: Nathwani
authors.forename: Clinton F
authors.initials: CF
authors.lastname: Stewart
authors.forename: Lawrence M
authors.initials: LM
authors.lastname: Pfeffer
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Davidoff
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D003606:Dacarbazine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm; D015971:Gene Expression Regulation, Enzymologic; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D016899:Interferon-beta / Q000378:metabolism*; D007378:Interleukins / Q000502:physiology*; D008297:Male; D051379:Mice; D016513:Mice, SCID; D009368:Neoplasm Transplantation; D009447:Neuroblastoma / Q000188:drug therapy* / Q000378:metabolism*; D019853:O(6)-Methylguanine-DNA Methyltransferase / Q000378:metabolism*; D000077204:Temozolomide; D000099180:Interleukin-24
chemical_list: D000970:Antineoplastic Agents; D003606:Dacarbazine; D016899:Interferon-beta; D007378:Interleukins; D019853:O(6)-Methylguanine-DNA Methyltransferase; D000077204:Temozolomide; D000099180:Interleukin-24