Gene silencing resulting from aberrant DNA methylation can lead to tumorigenesis. Therefore, drugs that inhibit or interfere with DNA methylation have been used to reactivate and induce silenced gene re-expression in malignancies. Two demethylating agents, azacitidine and decitabine, are approved for the treatment of myelodysplastic syndromes (MDS) by the U.S. Food and Drug Administration (FDA), and are now considered the standard of care in MDS. In this review, we discuss clinical data, including clinical benefits and toxicities, which led to the approval of azacitidine and decitabine. We also summarize findings from clinical trials that used these two demethylating agents in the treatment of solid tumors. Lastly, we discuss some limitations in the use of azacitidine and decitabine in cancer therapy.
References
[1]
Herman, J.G.; Baylin, S.B. Gene silencing in cancer in association with promoter hypermethylation. New Engl. J. Med.？2003, 349, 2042–2054, doi:10.1056/NEJMra023075. 14627790
[2]
Fleischhacker, M.; Schmidt, B. Circulating nucleic acids (CNAs) and cancer--a survey. Biochim. Biophys. Acta？2007, 1775, 181–232. 17137717
[3]
McCabe, M.T.; Brandes, J.C.; Vertino, P.M. Cancer DNA methylation: molecular mechanisms and clinical implications. Clin. Cancer Res.？2009, 15, 3927–3937, doi:10.1158/1078-0432.CCR-08-2784. 19509173
[4]
Tost, J. Analysis of DNA methylation patterns for the early diagnosis, classification and therapy of human cancers. In DNA Methylation Research Trends; Kobayashi, T.B., Ed.; Nova Science Publishers: Hauppauge, NY, USA, 2007; pp. 87–133.
[5]
Tost, J. DNA methylation: an introduction to the biology and the disease-associated changes of a promising biomarker. Mol. Biotechnol.？2010, 44, 71–81, doi:10.1007/s12033-009-9216-2. 19842073
D'Alessio, A.C.; Szyf, M. Epigenetic tête-à-tête: the bilateral relationship between chromatin modifications and DNA methylation. Biochem. Cell Biol.？2006, 84, 463–476, doi:10.1139/o06-090. 16936820
[8]
Jair, K.W.; Bachman, K.E.; Suzuki, H.; Ting, A.H.; Rhee, I.; Yen, R.W.; Baylin, S.B.; Schuebel, K.E. De novo CpG island methylation in human cancer cells. Cancer Res.？2006, 66, 682–692, doi:10.1158/0008-5472.CAN-05-1980. 16423997
[9]
Ting, A.H.; Jair, K.W.; Schuebel, K.E.; Baylin, S.B. Differential requirement for DNA methyltransferase 1 in maintaining human cancer cell gene promoter hypermethylation. Cancer Res.？2006, 66, 729–735, doi:10.1158/0008-5472.CAN-05-1537. 16424002
[10]
Takai, D.; Jones, P.A. Comprehensive analysis of CpG islands in human chromosomes 21 and 22. Proc. Natl. Acad. Sci. USA？2002, 99, 3740–3745, doi:10.1073/pnas.052410099. 11891299
[11]
Wang, Y.; Leung, F.C. An evaluation of new criteria for CpG islands in the human genome as gene markers. Bioinformatics？2004, 20, 1170–1177, doi:10.1093/bioinformatics/bth059. 14764558
[12]
Suzuki, M.M.; Bird, A. DNA methylation landscapes: provocative insights from epigenomics. Nat. Rev. Genet.？2008, 9, 465–476. 18463664
[13]
Geiman, T.M.; Muegge, K. DNA methylation in early development. Mol. Reprod. Dev.？2010, 77, 105–113. 19921744
[14]
Guibert, S.; Forne, T.; Weber, M. Dynamic regulation of DNA methylation during mammalian development. Epigenomics？2009, 1, 81–98, doi:10.2217/epi.09.5. 22122638
[15]
Reik, W.; Dean, W.; Walter, J. Epigenetic reprogramming in mammalian development. Science？2001, 293, 1089–1093, doi:10.1126/science.1063443. 11498579
[16]
Goto, T.; Monk, M. Regulation of X-chromosome inactivation in development in mice and humans. Microbiol. Mol. Biol. Rev.？1998, 62, 362–378. 9618446
[17]
Barlow, D.P. Gametic imprinting in mammals. Science (New York, N.Y.).？1995, 270, 1610–1613. 7502071
[18]
Baylin, S.B. DNA methylation and gene silencing in cancer. Nat. Clin. Pract. Oncol.？2005, 2 Suppl. 1, S4–S11, doi:10.1038/ncponc0354. 16341240
[19]
Esteller, M.; Garcia-Foncillas, J.; Andion, E.; Goodman, S.N.; Hidalgo, O.F.; Vanaclocha, V.; Baylin, S.B.; Herman, J.G. Inactivation of the DNA-repair gene MGMT and the clinical response of gliomas to alkylating agents. New Engl. J. Med.？2000, 343, 1350–1354, doi:10.1056/NEJM200011093431901. 11070098
[20]
Hegi, M.E.; Diserens, A.C.; Gorlia, T.; Hamou, M.F.; de Tribolet, N.; Weller, M.; Kros, J.M.; Hainfellner, J.A.; Mason, W.; Mariani, L.; Bromberg, J.E.; Hau, P.; Mirimanoff, R.O.; Cairncross, J.G.; Janzer, R.C.; Stupp, R. MGMT gene silending and benefit from temozolomide in glioblastoma. New Engl. J. Med.？2005, 352, 997–1003, doi:10.1056/NEJMoa043331. 15758010
[21]
Hegi, M.E.; Liu, L.; Herman, J.G.; Stupp, R.; Wick, W.; Weller, M.; Mehta, M.P.; Gilbert, M.R. Correlation of O6-methylguanine methyltransferase (MGMT) promoter methylation with clinical outcomes in glioblastoma and clinical strategies to modulate MGMT activity. J. Clin. Oncol.？2008, 26, 4189–4199. 18757334
[22]
Weller, M.; Stupp, R.; Reifenberger, G.; Brandes, A.A.; van den Bent, M.J.; Wick, W.; Hegi, M.E. MGMT promoter methylation in malignant gliomas: ready for personalized medicine? Nat. Rev. Neurol.？2010, 6, 39–51. 19997073
[23]
Smith, J.F.; Mahmood, S.; Song, F.; Morrow, A.; Smiraglia, D.; Zhang, X.; Rajput, A.; Higgins, M.J.; Krumm, A.; Petrelli, N.J.; Costello, J.F.; Nagase, H.; Plass, C.; Held, W.A. Identification of DNA methylation in 3' genomic regions that are associated with upregulation of gene expression in colorectal cancer. Epigenetics？2007, 2, 161–172, doi:10.4161/epi.2.3.4805. 17965620
[24]
Weber, M.; Davies, J.J.; Wittig, D.; Oakeley, E.J.; Haase, M.; Lam, W.L.; Schubeler, D. Chromosome-wide and promoter-specific analyses identify sites of differential DNA methylation in normal and transformed human cells. Nat. Genet.？2005, 37, 853–862, doi:10.1038/ng1598. 16007088
[25]
Mund, C.; Brueckner, B.; Lyko, F. Reactivation of epigenetically silenced genes by DNA methyltransferase inhibitors: basic concepts and clinical applications. Epigenetics？2006, 1, 7–13, doi:10.4161/epi.1.1.2375. 17998812
[26]
Feinberg, A.P.; Vogelstein, B. Hypomethylation distinguishes genes of some human cancers from their normal counterparts. Nature？1983, 301, 89–92, doi:10.1038/301089a0. 6185846
[27]
Gama-Sosa, M.A.; Slagel, V.A.; Trewyn, R.W.; Oxenhandler, R.; Kuo, K.C.; Gehrke, C.W.; Ehrlich, M. The 5-methylcytosine content of DNA from human tumors. Nuclecic Acids Res.？1983, 11, 6883–6894, doi:10.1093/nar/11.19.6883.
[28]
Lapeyre, J.N.; Becker, F.F. 5-Methylcytosine content of nuclear DNA during chemical hepatocarcinogenesis and in carcinomas which result. Biochem. Biophys. Res. Commun.？1979, 87, 698–705, doi:10.1016/0006-291X(79)92015-1. 454420
[29]
Lapeyre, J.N.; Walker, M.S.; Becker, F.F. DNA methylation and methylase levels in normal and malignant mouse hepatic tissues. Carcinogenesis？1981, 2, 873–878, doi:10.1093/carcin/2.9.873. 6271414
[30]
Zilberman, D.; Henikoff, S. Genome-wide analysis of DNA methylation patterns. Development？2007, 134, 3959–3965, doi:10.1242/dev.001131. 17928417
Schlesinger, Y.; Straussman, R.; Keshet, I.; Farkash, S.; Hecht, M.; Zimmerman, J.; Eden, E.; Yakhini, Z.; Ben-Shushan, E.; Reubinoff, B.E.; Bergman, Y.; Simon, I.; Cedar, H. Polycomb-mediated methylation on Lys27 of histone H3 pre-marks genes for de novo methylation in cancer. Nat. Genet.？2007, 39, 232–236, doi:10.1038/ng1950. 17200670
[39]
Filkowski, J.; Ilnytskyy, Y.; Tamminga, J.; Koturbash, I.; Golubov, A.; Bagnyukova, T.; Pogribny, I.; Kovalchuk, O. Hypomethylation and genome instability in the germline of exposed parents and their progeny is associated with altered miRNA expression. Carcinogenesis？2009.
[40]
Khraiwesh, B.; Arif, M.A.; Seumel, G.I.; Ossowski, S.; Weigel, D.; Reski, R.; Frank, W. Transcriptional control of gene expression by microRNAs. Cell？2010, 140, 111–122, doi:10.1016/j.cell.2009.12.023. 20085706
[41]
Sinkkonen, L.; Hugenschmidt, T.; Berninger, P.; Gaidatzis, D.; Mohn, F.; Artus-Revel, C.G.; Zavolan, M.; Svoboda, P.; Filipowicz, W. MicroRNAs control de novo DNA methylation through regulation of transcriptional repressors in mouse embryonic stem cells. Nat. Struct. Mol. Biol.？2008, 15, 259–267, doi:10.1038/nsmb.1391. 18311153
[42]
Ting, A.H.; Suzuki, H.; Cope, L.; Schuebel, K.E.; Lee, B.H.; Toyota, M.; Imai, K.; Shinomura, Y.; Tokino, T.; Baylin, S.B. A requirement for DICER to maintain full promoter CpG island hypermethylation in human cancer cells. Cancer Res.？2008, 68, 2570–2575, doi:10.1158/0008-5472.CAN-07-6405. 18413723
[43]
Huang, Y.; Anderle, P.; Bussey, K.J.; Barbacioru, C.; Shankavaram, U.; Dai, Z.; Reinhold, W.C.; Papp, A.; Weinstein, J.N.; Sadee, W. Membrane transporters and channels: role of the transportome in cancer chemosensitivity and chemoresistance. Cancer Res.？2004, 64, 4294–4301, doi:10.1158/0008-5472.CAN-03-3884. 15205344
[44]
Qin, T.; Jelinek, J.; Si, J.; Shu, J.; Issa, J.P. Mechanisms of resistance to 5-aza-2'-deoxycytidine in human cancer cell lines. Blood？2009, 113, 659–667, doi:10.1182/blood-2008-02-140038. 18931345
[45]
Rius, M.; Stresemann, C.; Keller, D.; Brom, M.; Schirrmacher, E.; Keppler, D.; Lyko, F. Human concentrative nucleoside transporter 1-mediated uptake of 5-azacytidine enhances DNA demethylation. Mol. Cancer Ther.？2009, 8, 225–231, doi:10.1158/1535-7163.MCT-08-0743. 19139132
[46]
Christman, J.K. 5-Azacytidine and 5-aza-2'-deoxycytidine as inhibitors of DNA methylation: mechanistic studies and their implications for cancer therapy. Oncogene？2002, 21, 5483–5495, doi:10.1038/sj.onc.1205699. 12154409
[47]
Flatau, E.; Gonzales, F.A.; Michalowsky, L.A.; Jones, P.A. DNA methylation in 5-aza-2'-deoxycytidine-resistant variants of C3H 10T1/2 C18 cells. Mol. Cell Biol.？1984, 4, 2098–2102. 6209556
[48]
Momparler, R.L.; Bouchard, J.; Onetto, N.; Rivard, G.E. 5-aza-2'-deoxycytidine therapy in patients with acute leukemia inhibits DNA methylation. Leukemia？1984, 8, 181–185, doi:10.1016/0145-2126(84)90141-3.
[49]
Chabner, B.A.; Drake, J.C.; Johns, D.G. Deamination of 5-azacytidine by a human leukemia cell cytidine deaminase. Biochem. Pharmacol.？1973, 22, 2763–2765, doi:10.1016/0006-2952(73)90137-8. 4128550
[50]
van Groeningen, C.J.; Leyva, A.; O'Brien, A.M.; Gall, H.E.; Pinedo, H.M. Phase I and pharmacokinetic study of 5-aza-2'-deoxycytidine (NSC 127716) in cancer patients. Cancer Res.？1986, 46, 4831–4836. 2425959
[51]
Creusot, F.; Acs, G.; Christman, J.K. Inhibition of DNA methyltransferase and induction of Friend erythroleukemia cell differentiation by 5-azacytidine and 5-aza-2'-deoxycytidine. J. Biol. Chem.？1982, 257, 2041–2048. 6173384
[52]
Ghoshal, K.; Datta, J.; Majumder, S.; Bai, S.; Kutay, H.; Motiwala, T.; Jacob, S.T. 5-Aza-deoxycytidine induces selective degradation of DNA methyltransferase 1 by a proteasomal pathway that requires the KEN box, bromo-adjacent homology domain, and nuclear localization signal. Mol. Cell Biol.？2005, 25, 4727–4741. 15899874
[53]
Stresemann, C.; Lyko, F. Modes of action of the DNA methyltransferase inhibitors azacytidine and decitabine. Int. J. Cancer？2008, 123, 8–13, doi:10.1002/ijc.23607. 18425818
[54]
Liu, Z.; Liu, S.; Xie, Z.; Blum, W.; Perrotti, D.; Paschka, P.; Klisovic, R.; Byrd, J.; Chan, K.K.; Marcucci, G. Characterization of in vitro and in vivo hypomethylating effects of decitabine in acute myeloid leukemia by a rapid, specific and sensitive LC-MS/MS method. Nuclecic Acids Res.？2007, 35, e31, doi:10.1093/nar/gkl1156.
[55]
Rountree, M.R.; Bachman, K.E.; Baylin, S.B. DNMT1 binds HDAC2 and a new co-repressor, DMAP1, to form a complex at replication foci. Nat. Genet.？2000, 25, 269–277. 10888872
[56]
Tatematsu, K.I.; Yamazaki, T.; Ishikawa, F. MBD2-MBD3 complex binds to hemi-methylated DNA and forms a complex containing DNMT1 at the replication foci in late S phase. Genes Cells？2000, 5, 677–688, doi:10.1046/j.1365-2443.2000.00359.x. 10947852
[57]
Juttermann, R.; Li, E.; Jaenisch, R. Toxicity of 5-aza-2'-deoxycytidine to mammalian cells is mediated primarily by covalent trapping of DNA methyltransferase rather than DNA demethylation. Proc. Natl. Acad. Sci. USA？1994, 91, 11797–11801, doi:10.1073/pnas.91.25.11797. 7527544
[58]
Issa, J.P.; Kantarjian, H.M. Targeting DNA methylation. Clin. Cancer Res.？2009, 15, 3938–3946, doi:10.1158/1078-0432.CCR-08-2783. 19509174
[59]
Von Hoff, D.D.; Slavik, M.; Muggia, F.M. 5-Azacytidine. A new anticancer drug with effectiveness in acute myelogenous leukemia. Ann. Intern. Med.？1976, 85, 237–245. 60073
[60]
Sorm, F.; Piskala, A.; Cihak, A.; Vesely, J. 5-Azacytidine, a new, highly effective cancerostatic. Experientia？1964, 20, 202–203. 5854157
[61]
Sorm, F.; Vesely, J. Effect of 5-aza-2'-deoxycytidine against leukemic and hemopoietic tissues in AKR mice. Neoplasma？1968, 15, 339–343. 5684460
[62]
Constantinides, P.G.; Jones, P.A.; Gevers, W. Funtional striated muscle cells from non-myoblast precursors following 5-azacytidine treatment. Nature？1977, 267, 364–366, doi:10.1038/267364a0. 68440
[63]
Taylor, S.M.; Jones, P.A. Multiple new phenotypes induced in 10T1/2 and 3T3 cells treated with 5-azacytidine. Cell？1979, 17, 771–779, doi:10.1016/0092-8674(79)90317-9. 90553
[64]
Jones, P.A. Effects of 5-azacytidine and its 2'-deoxyderivative on cell differentiation and DNA methylation. Pharmacol. Ther.？1985, 28, 17–27, doi:10.1016/0163-7258(85)90080-4. 2414786
[65]
Jones, P.A.; Taylor, S.M. Cellular differentiation, cytidine analogs and DNA methylation. Cell？1980, 20, 85–93, doi:10.1016/0092-8674(80)90237-8. 6156004
[66]
Issa, J.P.; Baylin, S.B.; Herman, J.G. DNA methylation changes in hematologic malignancies: biologic and clinical implications. Leukemia？1997, 11 Suppl. 1, S7–S11. 9130685
[67]
Ley, T.J.; DeSimone, J.; Anagnou, N.P.; Keller, G.H.; Humphries, R.K.; Turner, P.H.; Young, N.S.; Keller, P.; Nienhuis, A.W. 5-azacytidine selectively increases gamma-globin synthesis in a patient with beta+ thalassemia. New Engl. J. Med.？1982, 307, 1469–1475, doi:10.1056/NEJM198212093072401. 6183586
[68]
Charache, S.; Dover, G.; Smith, K.; Talbot, C.C., Jr.; Moyer, M.; Boyer, S. Treatment of sickle cell anemia with 5-azacytidine results in increased fetal hemoglobin production and is associated with nonrandom hypomethylation of DNA around the gamma-delta-beta-globin gene complex. Proc. Natl. Acad. Sci. USA？1983, 80, 4842–4846, doi:10.1073/pnas.80.15.4842. 6192443
[69]
Pinto, A.; Attadia, V.; Fusco, A.; Ferrara, F.; Spada, O.A.; Di Fiore, P.P. 5-Aza-2'-deoxycytidine induces terminal differentiation of leukemic blasts from patients with acute myeloid leukemias. Blood？1984, 64, 922–929. 6206904
[70]
Momparler, R.L.; Gonzales, F.A. Effect of intravenous infusion of 5-aza-2'-deoxycytidine on survival time of mice with L1210 leukemia. Cancer Res.？1978, 38, 2673–2678. 79443
[71]
Bellet, R.E.; Mastrangelo, M.J.; Engstrom, P.F.; Custer, R.P. Hepatotoxicity of 5-azacytidine (NSC-102816) (a clinical and pathologic study). Neoplasma？1973, 20, 303–309. 4125219
[72]
Santini, V.; Kantarjian, H.M.; Issa, J.P. Changes in DNA methylation in neoplasia: pathophysiology and therapeutic implications. Ann. Intern. Med.？2001, 134, 573–586, doi:10.7326/0003-4819-134-7-200104030-00011. 11281740
[73]
Tefferi, A.; Vardiman, J.W. Myelodysplastic syndromes. New Engl. J. Med.？2009, 361, 1872–1885, doi:10.1056/NEJMra0902908. 19890130
[74]
Bennett, J.M.; Catovsky, D.; Daniel, M.T.; Flandrin, G.; Galton, D.A.; Gralnick, H.R.; Sultan, C. Proposals for the classification of the myelodysplastic syndromes. Br. J. Haematol.？1982, 51, 189–199, doi:10.1111/j.1365-2141.1982.tb08475.x. 6952920
[75]
Bennett, J.M.; Kouides, P.A.; Forman, S.J. The myelodysplastic syndromes: morphology, risk assessment, and clinical management (2002). Int. J. Hematol.？2002, 76 Suppl. 2, 228–238. 12430930
[76]
Cheson, B.D.; Bennett, J.M.; Kantarjian, H.; Pinto, A.; Schiffer, C.A.; Nimer, S.D.; Lowenberg, B.; Beran, M.; de Witte, T.M.; Stone, R.M.; Mittelman, M.; Sanz, G.F.; Wijermans, P.W.; Gore, S.; Greenberg, P.L. Report of an international working group to standardize response criteria for myelodysplastic syndromes. Blood？2000, 96, 3671–3674. 11090046
[77]
Germing, U.; Gattermann, N.; Strupp, C.; Aivado, M.; Aul, C. Validation of the WHO proposals for a new classification of primary myelodysplastic syndromes: a retrospective analysis of 1600 patients. Leukemia？2000, 24, 983–992, doi:10.1016/S0145-2126(00)00088-6.
[78]
Harris, N.L.; Jaffe, E.S.; Diebold, J.; Flandrin, G.; Muller-Hermelink, H.K.; Vardiman, J.; Lister, T.A.; Bloomfield, C.D. World Health Organization classification of neoplastic diseases of the hematopoietic and lymphoid tissues: report of the Clinical Advisory Committee meeting-Airlie House, Virginia, November 1997. J. Clin. Oncol.？1999, 17, 3835–3849. 10577857
[79]
Vardiman, J.W.; Thiele, J.; Arber, D.A.; Brunning, R.D.; Borowitz, M.J.; Porwit, A.; Harris, N.L.; Le Beau, M.M.; Hellstrom-Lindberg, E.; Tefferi, A.; Bloomfield, C.D. The 2008 revision of the World Health Organization (WHO) classification of myeloid neoplasms and acute leukemia: rationale and important changes. Blood？2009, 114, 937–951, doi:10.1182/blood-2009-03-209262. 19357394
[80]
Mills, K.I.; Kohlmann, A.; Williams, P.M.; Wieczorek, L.; Liu, W.M.; Li, R.; Wei, W.; Bowen, D.T.; Loeffler, H.; Hernandez, J.M.; Hofmann, W.K.; Haferlach, T. Microarray-based classifiers and prognosis models identify subgroups with distinct clinical outcomes and high risk of AML transformation of myelodysplastic syndrome. Blood？2009, 114, 1063–1072, doi:10.1182/blood-2008-10-187203. 19443663
[81]
Silverman, L.R. Myelodysplastic syndrome. In Cancer Medicine, 5th; Bast, R.J., Kufe, D.W., Pollock, R.E., Weichselbaum, R.R., Holland, J.F., Frei, E., Gansler, T.S., Eds.; B.C. Decker Inc.: Hamilton, Ontario, 2000; pp. 1931–1946.
[82]
Rollison, D.E.; Howlader, N.; Smith, M.T.; Strom, S.S.; Merritt, W.D.; Ries, L.A.; Edwards, B.K.; List, A.F. Epidemiology of myelodysplastic syndromes and chronic myeloproliferative disorders in the United States, 2001-2004, using data from the NAACCR and SEER programs. Blood？2008, 112, 45–52. 18443215
[83]
Warlick, E.D.; Cioc, A.; Defor, T.; Dolan, M.; Weisdorf, D. Allogeneic stem cell transplantation for adults with myelodysplastic syndromes: importance of pretransplant disease burden. Biol. Blood Marrow Transplant.？2009, 15, 30–38. 19135940
[84]
Cutler, C.S.; Lee, S.J.; Greenberg, P.; Deeg, H.J.; Perez, W.S.; Anasetti, C.; Bolwell, B.J.; Cairo, M.S.; Gale, R.P.; Klein, J.P.; Lazarus, H.M.; Liesveld, J.L.; McCarthy, P.L.; Milone, G.A.; Rizzo, J.D.; Schultz, K.R.; Trigg, M.E.; Keating, A.; Weisdorf, D.J.; Antin, J.H.; Horowitz, M.M. A decision analysis of allogeneic bone marrow transplantation for the myelodysplastic syndromes: delayed transplantation for low-risk myelodysplasia is associated with improved outcome. Blood？2004, 104, 579–585, doi:10.1182/blood-2004-01-0338. 15039286
[85]
Silverman, L.R.; Demakos, E.P.; Peterson, B.L.; Kornblith, A.B.; Holland, J.C.; Odchimar-Reissig, R.; Stone, R.M.; Nelson, D.; Powell, B.L.; DeCastro, C.M.; Ellerton, J.; Larson, R.A.; Schiffer, C.A.; Holland, J.F. Randomized controlled trial of azacitidine in patients with the myelodysplastic syndrome: a study of the cancer and leukemia group B. J. Clin. Oncol.？2002, 20, 2429–2440, doi:10.1200/JCO.2002.04.117. 12011120
[86]
De Padua Silva, L.; de Lima, M.; Kantarjian, H.; Faderl, S.; Kebriaei, P.; Giralt, S.; Davisson, J.; Garcia-Manero, G.; Champlin, R.; Issa, J.P.; Ravandi, F. Feasibility of allo-SCT after hypomethylating therapy with decitabine for myelodysplastic syndrome. Bone Marrow Transplant.？2009, 43, 839–843, doi:10.1038/bmt.2008.400. 19151791
[87]
Lubbert, M.; Bertz, H.; Ruter, B.; Marks, R.; Claus, R.; Wasch, R.; Finke, J. Non-intensive treatment with low-dose 5-aza-2'-deoxycytidine (DAC) prior to allogeneic blood SCT of older MDS/AML patients. Bone Marrow Transplant.？2009, 44, 585–588, doi:10.1038/bmt.2009.64. 19363531
[88]
Silverman, L.; Holland, J.F.; Demakos, E.P. Azacitidine in myelodysplastic syndromes: CALGB studies 8421 and 8921. Ann. Hematol.？1994, 68, A12.
[89]
Silverman, L.R.; Holland, J.F.; Weinberg, R.S.; Alter, B.P.; Davis, R.B.; Ellison, R.R.; Demakos, E.P.; Cornell, C.J., Jr.; Carey, R.W.; Schiffer, C.; et al. Effects of treatment with 5-azacytidine on the in vivo and in vitro hematopoiesis in patients with myelodysplastic syndromes. Leukemia？1993, 7 Suppl. 1, 21–29. 7683352
[90]
Silverman, L.R.; McKenzie, D.R.; Peterson, B.L.; Holland, J.F.; Backstrom, J.T.; Beach, C.L.; Larson, R.A. Further analysis of trials with azacitidine in patients with myelodysplastic syndrome: studies 8421, 8921, and 9221 by the Cancer and Leukemia Group B. J. Clin. Oncol.？2006, 24, 3895–3903. 16921040
[91]
Marcucci, G.; Silverman, L.; Eller, M.; Lintz, L.; Beach, C.L. Bioavailability of azacitidine subcutaneous versus intravenous in patients with the myelodysplastic syndromes. J. Clin. Pharmacol.？2005, 45, 597–602. 15831784
[92]
Kaminskas, E.; Farrell, A.; Abraham, S.; Baird, A.; Hsieh, L.S.; Lee, S.L.; Leighton, J.K.; Patel, H.; Rahman, A.; Sridhara, R.; Wang, Y.C.; Pazdur, R. Approval summary: azacitidine for treatment of myelodysplastic syndrome subtypes. Clin. Cancer Res.？2005, 11, 3604–3608, doi:10.1158/1078-0432.CCR-04-2135. 15897554
[93]
Kornblith, A.B.; Herndon, J.E., 2nd; Silverman, L.R.; Demakos, E.P.; Odchimar-Reissig, R.; Holland, J.F.; Powell, B.L.; DeCastro, C.; Ellerton, J.; Larson, R.A.; Schiffer, C.A.; Holland, J.C. Impact of azacytidine on the quality of life of patients with myelodysplastic syndrome treated in a randomized phase III trial: a Cancer and Leukemia Group B study. J. Clin. Oncol.？2002, 20, 2441–2452. 12011121
[94]
Momparler, R.L.; Rivard, G.E.; Gyger, M. Clinical trial on 5-aza-2'-deoxycytidine in patients with acute leukemia. Pharmacol. Ther.？1985, 30, 277–286, doi:10.1016/0163-7258(85)90052-X. 2433702
[95]
Wijermans, P.; Lubbert, M.; Verhoef, G.; Bosly, A.; Ravoet, C.; Andre, M.; Ferrant, A. Low-dose 5-aza-2'-deoxycytidine, a DNA hypomethylating agent, for the treatment of high-risk myelodysplastic syndrome: a multicenter phase II study in elderly patients. J. Clin. Oncol.？2000, 18, 956–962. 10694544
[96]
Wijermans, P.W.; Krulder, J.W.; Huijgens, P.C.; Neve, P. Continuous infusion of low-dose 5-Aza-2'-deoxycytidine in elderly patients with high-risk myelodysplastic syndrome. Leukemia？1997, 11, 1–5, doi:10.1038/sj.leu.2400526. 9244824
[97]
Kantarjian, H.; Issa, J.P.; Rosenfeld, C.S.; Bennett, J.M.; Albitar, M.; DiPersio, J.; Klimek, V.; Slack, J.; de Castro, C.; Ravandi, F.; Helmer, R., 3rd; Shen, L.; Nimer, S.D.; Leavitt, R.; Raza, A.; Saba, H. Decitabine improves patient outcomes in myelodysplastic syndromes: results of a phase III randomized study. Cancer？2006, 106, 1794–1803. 16532500
[98]
Gore, S.D.; Jones, C.; Kirkpatrick, P. Decitabine. Nat. Rev. Drug Discov.？2006, 5, 891–892, doi:10.1038/nrd2180. 17117522
[99]
Steensma, D.P.; Baer, M.R.; Slack, J.L.; Buckstein, R.; Godley, L.A.; Garcia-Manero, G.; Albitar, M.; Larsen, J.S.; Arora, S.; Cullen, M.T.; Kantarjian, H. Multicenter study of decitabine administered daily for 5 days every 4 weeks to adults with myelodysplastic syndromes: the alternative dosing for outpatient treatment (ADOPT) trial. J. Clin. Oncol.？2009, 27, 3842–3848, doi:10.1200/JCO.2008.19.6550. 19528372
[100]
Fenaux, P.; Mufti, G.J.; Hellstrom-Lindberg, E.; Santini, V.; Finelli, C.; Giagounidis, A.; Schoch, R.; Gattermann, N.; Sanz, G.; List, A.; Gore, S.D.; Seymour, J.F.; Bennett, J.M.; Byrd, J.; Backstrom, J.; Zimmerman, L.; McKenzie, D.; Beach, C.; Silverman, L.R. Efficacy of azacitidine compared with that of conventional care regimens in the treatment of higher-risk myelodysplastic syndromes: a randomised, open-label, phase III study. Lancet Oncol.？2009, 10, 223–232. 19230772
[101]
Griffiths, E.A.; Gore, S.D. DNA methyltransferase and histone deacetylase inhibitors in the treatment of myelodysplastic syndromes. Semin. Hematol.？2008, 45, 23–30, doi:10.1053/j.seminhematol.2007.11.007. 18179966
[102]
Gurion, R.; Vidal, L.; Gafter-Gvili, A.; Belnik, Y.; Yeshurun, M.; Raanani, P.; Shpilberg, O. 5-azacitidine prolongs overall survival in patients with myelodysplastic syndrome--a systematic review and meta-analysis. Haematologica？2010, 95, 303–310, doi:10.3324/haematol.2009.010611. 19773261
Abele, R.; Clavel, M.; Dodion, P.; Bruntsch, U.; Gundersen, S.; Smyth, J.; Renard, J.; van Glabbeke, M.; Pinedo, H.M. The EORTC Early Clinical Trials Cooperative Group experience with 5-aza-2'-deoxycytidine (NSC 127716) in patients with colo-rectal, head and neck, renal carcinomas and malignant melanomas. Eur. J. Cancer Clin. Oncol.？1987, 23, 1921–1924. 2449354
[105]
Appleton, K.; Mackay, H.J.; Judson, I.; Plumb, J.A.; McCormick, C.; Strathdee, G.; Lee, C.; Barrett, S.; Reade, S.; Jadayel, D.; Tang, A.; Bellenger, K.; Mackay, L.; Setanoians, A.; Schatzlein, A.; Twelves, C.; Kaye, S.B.; Brown, R. Phase I and pharmacodynamic trial of the DNA methyltransferase inhibitor decitabine and carboplatin in solid tumors. J. Clin. Oncol.？2007, 25, 4603–4609, doi:10.1200/JCO.2007.10.8688. 17925555
Cunningham, T.J.; Nemoto, T.; Rosner, D.; Knight, E.; Taylor, S.; Rosenbaum, C.; Horton, J.; Dao, T. Comparison of 5-azacytidine (NSC-102816) with CCNU (NSC-79037) in the treatment of patients with breast cancer and evaluation of the subsequent use of cyclophosphamide (NSC-26271). Cancer Chemother. Rep.？1974, 58, 677–681. 4138966
[108]
Moertel, C.G.; Schutt, A.J.; Reitemeier, R.J.; Hahn, R.G. Phase II study of 5-azacytidine (NSC-102816) in the treatment of advanced gastrointestinal cancer. Cancer Chemother. Rep.？1972, 56, 649–652. 4119908
[109]
Momparler, R.L.; Bouffard, D.Y.; Momparler, L.F.; Dionne, J.; Belanger, K.; Ayoub, J. Pilot phase I-II study on 5-aza-2'-deoxycytidine (Decitabine) in patients with metastatic lung cancer. Anticancer Drugs？1997, 8, 358–368, doi:10.1097/00001813-199704000-00008. 9180389
[110]
Samuels, B.L.; Herndon, J.E., 2nd; Harmon, D.C.; Carey, R.; Aisner, J.; Corson, J.M.; Suzuki, Y.; Green, M.R.; Vogelzang, N.J. Dihydro-5-azacytidine and cisplatin in the treatment of malignant mesothelioma: a phase II study by the Cancer and Leukemia Group B. Cancer？1998, 82, 1578–1584. 9554537
[111]
Sessa, C.; ten Bokkel Huinink, W.; Stoter, G.; Renard, J.; Cavalli, F. Phase II study of 5-aza-2'-deoxycytidine in advanced ovarian carcinoma. The EORTC Early Clinical Trials Group. Eur. J. Cancer？1990, 26, 137–138, doi:10.1016/0277-5379(90)90295-5. 1691012
[112]
Thibault, A.; Figg, W.D.; Bergan, R.C.; Lush, R.M.; Myers, C.E.; Tompkins, A.; Reed, E.; Samid, D. A phase II study of 5-aza-2'deoxycytidine (decitabine) in hormone independent metastatic (D2) prostate cancer. Tumori？1998, 84, 87–89. 9619724
[113]
Weiss, A.J.; Metter, G.E.; Nealon, T.F.; Keanan, J.P.; Ramirez, G.; Swaiminathan, A.; Fletcher, W.S.; Moss, S.E.; Manthei, R.W. Phase II study of 5-azacytidine in solid tumors. Cancer Treat. Rep.？1977, 61, 55–58. 67894
[114]
Weiss, A.J.; Stambaugh, J.E.; Mastrangelo, M.J.; Laucius, J.F.; Bellet, R.E. Phase I study of 5-azacytidine (NSC-102816). Cancer Chemother. Rep.？1972, 56, 413–419. 19051503
[115]
Aparicio, A.; Weber, J.S. Review of the clinical experience with 5-azacytidine and 5-aza-2'-deoxycytidine in solid tumors. Curr. Opin. Investig. Drugs？2002, 3, 627–633. 12090735
[116]
Hellebrekers, D.M.; Jair, K.W.; Vire, E.; Eguchi, S.; Hoebers, N.T.; Fraga, M.F.; Esteller, M.; Fuks, F.; Baylin, S.B.; van Engeland, M.; Griffioen, A.W. Angiostatic activity of DNA methyltransferase inhibitors. Mol. Cancer Ther.？2006, 5, 467–475. 16505122
[117]
Samlowski, W.E.; Leachman, S.A.; Wade, M.; Cassidy, P.; Porter-Gill, P.; Busby, L.; Wheeler, R.; Boucher, K.; Fitzpatrick, F.; Jones, D.A.; Karpf, A.R. Evaluation of a 7-day continuous intravenous infusion of decitabine: inhibition of promoter-specific and global genomic DNA methylation. J. Clin. Oncol.？2005, 23, 3897–3905, doi:10.1200/JCO.2005.06.118. 15753459
[118]
Aparicio, A.; Eads, C.A.; Leong, L.A.; Laird, P.W.; Newman, E.M.; Synold, T.W.; Baker, S.D.; Zhao, M.; Weber, J.S. Phase I trial of continuous infusion 5-aza-2'-deoxycytidine. Cancer Chemother. Pharmacol.？2003, 51, 231–239. 12655442
[119]
Beyrouthy, M.J.; Garner, K.M.; Hever, M.P.; Freemantle, S.J.; Eastman, A.; Dmitrovsky, E.; Spinella, M.J. High DNA methyltransferase 3B expression mediates 5-aza-deoxycytidine hypersensitivity in testicular germ cell tumors. Cancer Res.？2009, 69, 9360–9366, doi:10.1158/0008-5472.CAN-09-1490. 19951990
[120]
Sonpavde, G.; Aparicio, A.M.; Zhan, F.; North, B.; Delaune, R.; Garbo, L.E.; Rousey, S.R.; Weinstein, R.E.; Xiao, L.; Boehm, K.A.; Asmar, L.; Fleming, M.T.; Galsky, M.D.; Berry, W.R.; Von Hoff, D.D. Azacitidine favorably modulates PSA kinetics correlating with plasma DNA LINE-1 hypomethylation in men with chemonaive castration-resistant prostate cancer. Urol. Oncol.？, 2009.
Ito, M.; Ito, G.; Kondo, M.; Uchiyama, M.; Fukui, T.; Mori, S.; Yoshioka, H.; Ueda, Y.; Shimokata, K.; Sekido, Y. Frequent inactivation of RASSF1A, BLU, and SEMA3B on 3p21.3 by promoter hypermethylation and allele loss in non-small cell lung cancer. Cancer Lett.？2005, 225, 131–139. 15922865
[123]
Mok, S.C.; Chan, W.Y.; Wong, K.K.; Muto, M.G.; Berkowitz, R.S. SPARC, an extracellular matrix protein with tumor-suppressing activity in human ovarian epithelial cells. Oncogene？1996, 12, 1895–1901. 8649850
[124]
Sato, N.; Fukushima, N.; Maehara, N.; Matsubayashi, H.; Koopmann, J.; Su, G.H.; Hruban, R.H.; Goggins, M. SPARC/osteonectin is a frequent target for aberrant methylation in pancreatic adenocarcinoma and a mediator of tumor-stromal interactions. Oncogene？2003, 22, 5021–5030, doi:10.1038/sj.onc.1206807. 12902985
[125]
Sova, P.; Feng, Q.; Geiss, G.; Wood, T.; Strauss, R.; Rudolf, V.; Lieber, A.; Kiviat, N. Discovery of novel methylation biomarkers in cervical carcinoma by global demethylation and microarray analysis. Cancer Epidemiol. Biomarkers Prev.？2006, 15, 114–123, doi:10.1158/1055-9965.EPI-05-0323. 16434596
[126]
Suzuki, M.; Hao, C.; Takahashi, T.; Shigematsu, H.; Shivapurkar, N.; Sathyanarayana, U.G.; Iizasa, T.; Fujisawa, T.; Hiroshima, K.; Gazdar, A.F. Aberrant methylation of SPARC in human lung cancers. Br. J. Cancer？2005, 92, 942–948, doi:10.1038/sj.bjc.6602376. 15756262
[127]
Yang, E.; Kang, H.J.; Koh, K.H.; Rhee, H.; Kim, N.K.; Kim, H. Frequent inactivation of SPARC by promoter hypermethylation in colon cancers. Int. J. Cancer？2007, 121, 567–575, doi:10.1002/ijc.22706. 17397030
[128]
Koblinski, J.E.; Kaplan-Singer, B.R.; VanOsdol, S.J.; Wu, M.; Engbring, J.A.; Wang, S.; Goldsmith, C.M.; Piper, J.T.; Vostal, J.G.; Harms, J.F.; Welch, D.R.; Kleinman, H.K. Endogenous osteonectin/SPARC/BM-40 expression inhibits MDA-MB-231 breast cancer cell metastasis. Cancer Res.？2005, 65, 7370–7377, doi:10.1158/0008-5472.CAN-05-0807. 16103089
[129]
Yoo, C.B.; Jeong, S.; Egger, G.; Liang, G.; Phiasivongsa, P.; Tang, C.; Redkar, S.; Jones, P.A. Delivery of 5-aza-2’-deoxycytidine to cells using oligodeoxynucleotides. Cancer Res.？2007, 67, 6400–6408, doi:10.1158/0008-5472.CAN-07-0251. 17616700
[130]
Gaudet, F.; Hodgson, J.G.; Eden, A.; Jackson-Grusby, L.; Dausman, J.; Gray, J.W.; Leonhardt, H.; Jaenisch, R. Induction of tumors in mice by genomic hypomethylation. Science？2003, 300, 489–492, doi:10.1126/science.1083558. 12702876
[131]
Howard, G.; Eiges, R.; Gaudet, F.; Jaenisch, R.; Eden, A. Activation and transposition of endogenous retroviral elements in hypomethylation induced tumors in mice. Oncogene？2008, 27, 404–408, doi:10.1038/sj.onc.1210631. 17621273
[132]
Kantharidis, P.; El-Osta, A.; deSilva, M.; Wall, D.M.; Hu, X.F.; Slater, A.; Nadalin, G.; Parkin, J.D.; Zalcberg, J.R. Altered methylation of the human MDR1 promoter is associated with acquired multidrug resistance. Clin. Cancer Res.？1997, 3, 2025–2032. 9815593
[133]
Hubeek, I.; Stam, R.W.; Peters, G.J.; Broekhuizen, R.; Meijerink, J.P.; van Wering, E.R.; Gibson, B.E.; Creutzig, U.; Zwaan, C.M.; Cloos, J.; Kuik, D.J.; Pieters, R.; Kaspers, G.J. The human equilibrative nucleoside transporter 1 mediates in vitro cytarabine sensitivity in childhood acute myeloid leukaemia. Br. J. Cancer？2005, 93, 1388–1394. 16333246
[134]
Lemaire, M.; Chabot, G.G.; Raynal, N.J.; Momparler, L.F.; Hurtubise, A.; Bernstein, M.L.; Momparler, R.L. Importance of dose-schedule of 5-aza-2'-deoxycytidine for epigenetic therapy of cancer. BMC Cancer？2008, 8, 128, doi:10.1186/1471-2407-8-128. 18454857
[135]
Adams, R.L.; Fulton, J.; Kirk, D. The effect of 5-azadeoxycytidine on cell growth and DNA methylation. Biochim. Biophys. Acta.？1982, 697, 286–294, doi:10.1016/0167-4781(82)90091-4. 6179542
[136]
Stegmann, A.P.; Honders, M.W.; Willemze, R.; Landegent, J.E. De novo induced mutations in the deoxycytidine kinase (dck) gene in rat leukemic clonal cell lines confer resistance to cytarabine (AraC) and 5-aza-2'-deoxycytidine (DAC). Leukemia？1995, 9, 1032–1038. 7541096
[137]
Park, M.T.; Lee, S.J. Cell cycle and cancer. J. Biochem. Mol. Biol.？2003, 36, 60–65, doi:10.5483/BMBRep.2003.36.1.060. 12542976
[138]
Quesnel, B.; Guillerm, G.; Vereecque, R.; Wattel, E.; Preudhomme, C.; Bauters, F.; Vanrumbeke, M.; Fenaux, P. Methylation of the p15(INK4b) gene in myelodysplastic syndromes is frequent and acquired during disease progression. Blood？1998, 91, 2985–2990. 9531610
[139]
Daskalakis, M.; Nguyen, T.T.; Nguyen, C.; Guldberg, P.; Kohler, G.; Wijermans, P.; Jones, P.A.; Lubbert, M. Demethylation of a hypermethylated P15/INK4B gene in patients with myelodysplastic syndrome by 5-Aza-2'-deoxycytidine (decitabine) treatment. Blood？2002, 100, 2957–2964, doi:10.1182/blood.V100.8.2957. 12351408
[140]
Aparicio, A.; North, B.; Barske, L.; Wang, X.; Bollati, V.; Weisenberger, D.; Yoo, C.; Tannir, N.; Horne, E.; Groshen, S.; Jones, P.; Yang, A.; Issa, J.P. LINE-1 methylation in plasma DNA as a biomarker of activity of DNA methylation inhibitors in patients with solid tumors. Epigenetics？2009, 4, 176–184, doi:10.4161/epi.4.3.8694. 19421002
[141]
Blum, W.; Garzon, R.; Klisovic, R.B.; Schwind, S.; Walker, A.; Geyer, S.; Liu, S.; Havelange, V.; Becker, H.; Schaaf, L.; Mickle, J.; Devine, H.; Kefauver, C.; Devine, S.M.; Chan, K.K.; Heerema, N.A.; Bloomfield, C.D.; Grever, M.R.; Byrd, J.C.; Villalona-Calero, M.; Croce, C.M.; Marcucci, G. Clinical response and miR-29b predictive significance in older AML patients treated with a 10-day schedule of decitabine. Proc. Natl. Acad. Sci. U S A？2010, 107, 7473–7478, doi:10.1073/pnas.1002650107. 20368434
[142]
Shen, L.; Kantarjian, H.; Guo, Y.; Lin, E.; Shan, J.; Huang, X.; Berry, D.; Ahmed, S.; Zhu, W.; Pierce, S.; Kondo, Y.; Oki, Y.; Jelinek, J.; Saba, H.; Estey, E.; Issa, J.P. DNA methylation predicts survival and response to therapy in patients with myelodysplastic syndromes. J. Clin. Oncol.？2010, 28, 605–613, doi:10.1200/JCO.2009.23.4781. 20038729
[143]
Jiang, Y.; Dunbar, A.; Gondek, L.P.; Mohan, S.; Rataul, M.; O'Keefe, C.; Sekeres, M.; Saunthararajah, Y.; Maciejewski, J.P. Aberrant DNA methylation is a dominant mechanism in MDS progression to AML. Blood？2009, 113, 1315–1325, doi:10.1182/blood-2008-06-163246. 18832655
[144]
De Schutter, H.; Nuyts, S. Radiosensitizing potential of epigenetic anticancer drugs. Anticancer Agents Med. Chem.？2009, 9, 99–108, doi:10.2174/187152009787047707. 19149485
[145]
Lavelle, D.; Chin, J.; Vaitkus, K.; Redkar, S.; Phiasivongsa, P.; Tang, C.; Will, R.; Hankewych, M.; Roxas, B.; Singh, M.; Saunthararajah, Y.; Desimone, J. Oral decitabine reactivates expression of the methylated gamma-globin gene in Papio anubis. Am. J. Hematol.？2007, 82, 981–985, doi:10.1002/ajh.21020. 17696208
[146]
Garcia-Manero, G.; Stoltz, M.L.; Ward, M.R.; Kantarjian, H.; Sharma, S. A pilot pharmacokinetic study of oral azacitidine. Leukemia？2008, 22, 1680–1684, doi:10.1038/leu.2008.145. 18548103
