DNA methyltransferase inhibitor, zebularine, delays tumor growth and induces apoptosis in a genetically engineered mouse model of breast cancer.
Zebularine is a novel potent inhibitor of both cytidine deaminase and DNA methylation. We examined the effect of zebularine on mammary tumor growth in genetically engineered MMTV-PyMT transgenic mice that develop mammary tumors at 60 days of age with 100% penetrance. The MMTV-PyMT transgenic mice were randomized at 46 days of age into control (n = 25) and zebularine (n = 25) treatment groups and monitored for parameters of tumor growth. Zebularine was administered at 5 mg/mL in drinking water. We observed a significant delay in the growth of mammary tumors in zebularine-treated mice with a statistically significant reduction (P = 0.0135) in total tumor burden at 94 days of age when the mice were sacrificed. After 48 days of zebularine treatment, the tumors were predominantly necrotic compared with untreated animals. In addition, a high apoptotic index by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was observed as early as 13 days following treatment. Immunoblot analysis showed depletion of DNMT1 and partial depletion of DNMT3b after zebularine treatment. Microarray analyses of global gene expression identified upregulation of twelve methylation-regulated genes as well as a set of candidate cancer genes that participate in cell growth and apoptosis. In summary, zebularine inhibits the growth of spontaneous mammary tumors and causes early onset of tumor cell necrosis and apoptosis in a genetically engineered mouse model of breast cancer. Defining the parameters of zebularine-mediated tumor inhibition may advance the future development of DNA methyltransferase inhibitors as an effective cancer treatment.
Department of Anatomy and Cell Biology, University of Florida, College of Medicine, Gainesville, FL 32610, USA.
Min
M
Chen
Daniel
D
Shabashvili
Akbar
A
Nawab
Sherry X
SX
Yang
Lisa M
LM
Dyer
Kevin D
KD
Brown
Melinda
M
Hollingshead
Kent W
KW
Hunter
Frederic J
FJ
Kaye
Steven N
SN
Hochwald
Victor E
VE
Marquez
Patricia
P
Steeg
Maria
M
Zajac-Kaye
D000284:Administration, Oral; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000235:genetics; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D003562:Cytidine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors / Q000378:metabolism; D019175:DNA Methylation / Q000187:drug effects; D004195:Disease Models, Animal; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D015151:Immunoblotting; D008325:Mammary Neoplasms, Experimental / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009336:Necrosis / Q000139:chemically induced; D020411:Oligonucleotide Array Sequence Analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D047368:Tumor Burden / Q000187:drug effects*; D000097584:DNA Methyltransferase 3B
D000952:Antigens, Polyomavirus Transforming; D003562:Cytidine; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; D000097584:DNA Methyltransferase 3B; C009131:pyrimidin-2-one beta-ribofuranoside; C000619380:DNMT1 protein, human; C000619381:Dnmt1 protein, mouse