title: Antitumor effects of a combined 5-aza-2'deoxycytidine and valproic acid treatment on rhabdomyosarcoma and medulloblastoma in Ptch mutant mice.
abstract: Patched (Ptch) heterozygous mice develop medulloblastoma (MB) and rhabdomyosarcoma (RMS) resembling the corresponding human tumors. We have previously shown that epigenetic silencing of the intact Ptch allele contributes to tumor formation in this model. Here, we investigated whether targeting of epigenetic silencing mechanisms could be useful in the treatment of Ptch-associated cancers. A reduction of endogenous DNA methyltransferase1 (Dnmt1) activity significantly reduced tumor incidence in heterozygous Ptch knockout mice. A combined treatment with the Dnmt inhibitor 5-aza-2'deoxycytidine (5-aza-dC) and the histone deacetlyase (HDAC) inhibitor valproic acid (VPA) efficiently prevented MB and RMS formation, whereas monotherapies with either drug were less effective. Wild-type Ptch expression was efficiently reactivated in tumors by 5-aza-dC/VPA combination therapy. This was associated with reduced methylation of the Ptch promoter and induction of histone hyperacetylation suggesting inhibition of HDACs in vivo. However, the treatment was not effective in clinically overt, advanced stage tumors. This is a first in vivo demonstration that targeting of Dnmt and HDAC activities is highly effective in preventing formation of Ptch-associated tumors. The results suggest a novel clinical strategy for consolidation therapy of corresponding tumors in humans after completion of conventional treatment. Our data also suggest that epigenetic therapy may be less effective in treating advanced stages of tumors, at least in this tumor model.
authors.affiliation: Institute of Human Genetics, University of Goettingen, Göttingen, Germany.
authors.forename: Ines
authors.initials: I
authors.lastname: Ecke
authors.forename: Frauke
authors.initials: F
authors.lastname: Petry
authors.forename: Albert
authors.initials: A
authors.lastname: Rosenberger
authors.forename: Svantje
authors.initials: S
authors.lastname: Tauber
authors.forename: Sven
authors.initials: S
authors.lastname: Mönkemeyer
authors.forename: Ina
authors.initials: I
authors.lastname: Hess
authors.forename: Christian
authors.initials: C
authors.lastname: Dullin
authors.forename: Sarah
authors.initials: S
authors.lastname: Kimmina
authors.forename: Judith
authors.initials: J
authors.lastname: Pirngruber
authors.forename: Steven A
authors.initials: SA
authors.lastname: Johnsen
authors.forename: Anja
authors.initials: A
authors.lastname: Uhmann
authors.forename: Frauke
authors.initials: F
authors.lastname: Nitzki
authors.forename: Leszek
authors.initials: L
authors.lastname: Wojnowski
authors.forename: Walter
authors.initials: W
authors.lastname: Schulz-Schaeffer
authors.forename: Olaf
authors.initials: O
authors.lastname: Witt
authors.forename: Heidi
authors.initials: H
authors.lastname: Hahn
mesh_terms: D000107:Acetylation; D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D001374:Azacitidine / Q000008:administration & dosage / Q000031:analogs & derivatives; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019175:DNA Methylation; D000077209:Decitabine; D015870:Gene Expression / Q000187:drug effects; D020868:Gene Silencing; D056572:Histone Deacetylase Inhibitors; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000378:metabolism; D008527:Medulloblastoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D011956:Receptors, Cell Surface / Q000235:genetics*; D012208:Rhabdomyosarcoma / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D014635:Valproic Acid / Q000008:administration & dosage
chemical_list: D056572:Histone Deacetylase Inhibitors; D006657:Histones; C000606236:PTCH1 protein, human; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; C000606240:Ptch1 protein, mouse; D011956:Receptors, Cell Surface; D014635:Valproic Acid; D000077209:Decitabine; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619380:DNMT1 protein, human; C000619381:Dnmt1 protein, mouse; D006655:Histone Deacetylases; D001374:Azacitidine