| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Carcinogenesis |
Division of Biochemical Toxicology, National Center for Toxicological Research, Jefferson, Arkansas 72079 [M. P., S. J. J.]; Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205 [I. P. P., S. J. J.]; and Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska 68198 [J. K. C.]
It is not known whether transcriptional suppression by de novo methylation occurs within the promoter region of the p53 gene during multistage tumorigenesis. To address this question, in vivo alterations in the CpG methylation within the rat p53 promoter region were evaluated in control, preneoplastic, and tumor tissue during tumor progression using the folate/methyl-deficient model of hepatocarcinogenesis. Alterations in CpG methylation were found to be site-specific and to vary depending on the stage of carcinogenesis. To further explore the effect of site-specific methylation on p53 promoter activity, reporter gene constructs were prepared containing specifically methylated sites within the p53 promoter region, and the transcriptional activity in cultured mammalian cells was determined in a transient transfection assay. Relative to the unmethylated construct as a positive control, single-site methylation at nucleotide (nt) -450, which occurs 216 nt upstream from the 85-nt minimal promoter region, suppressed promoter activity by 85%. In contrast, single-site methylation at nt -179, which occurs within the minimal essential promoter region, suppressed activity by only 20%. The p53 promoter constructs containing the singly methylated CpG site at nt -450 were then reevaluated for processive changes in methylation status 48 h after transfection, during maximum suppression of promoter activity. Restriction analysis with methylation-sensitive enzymes revealed that de novo methylation had occurred after transfection at previously unmethylated sites. These findings suggest that nt -450 may constitute a critical site for initiation of de novo methylation and processive spreading of methylation associated with transcriptional inactivation of the p53 gene. Furthermore, the results suggest a possible alternative mechanism for the silencing of the p53 gene in tumors that do not have p53 mutations.
This article has been cited by other articles:
![]() |
F. Crea, E. Giovannetti, F. Cortesi, V. Mey, S. Nannizzi, M. I. Gallegos Ruiz, S. Ricciardi, M. Del Tacca, G. J. Peters, and R. Danesi Epigenetic mechanisms of irinotecan sensitivity in colorectal cancer cell lines Mol. Cancer Ther., July 1, 2009; 8(7): 1964 - 1973. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. Knock, L. Deng, Q. Wu, D. Leclerc, X.-l. Wang, and R. Rozen Low Dietary Folate Initiates Intestinal Tumors in Mice, with Altered Expression of G2-M Checkpoint Regulators Polo-Like Kinase 1 and Cell Division Cycle 25c Cancer Res., November 1, 2006; 66(21): 10349 - 10356. [Abstract] [Full Text] [PDF] |
||||
![]() |
I. P. Pogribny, S. A. Ross, V. P. Tryndyak, M. Pogribna, L. A. Poirier, and T. V. Karpinets Histone H3 lysine 9 and H4 lysine 20 trimethylation and the expression of Suv4-20h2 and Suv-39h1 histone methyltransferases in hepatocarcinogenesis induced by methyl deficiency in rats Carcinogenesis, June 1, 2006; 27(6): 1180 - 1186. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. P. Whitman, S. Liu, T. Vukosavljevic, L. J. Rush, L. Yu, C. Liu, M. I. Klisovic, K. Maharry, M. Guimond, M. P. Strout, et al. The MLL partial tandem duplication: evidence for recessive gain-of-function in acute myeloid leukemia identifies a novel patient subgroup for molecular-targeted therapy Blood, July 1, 2005; 106(1): 345 - 352. [Abstract] [Full Text] [PDF] |
||||
![]() |
D. R. Hodge, B. Peng, J. C. Cherry, E. M. Hurt, S. D. Fox, J. A. Kelley, D. J. Munroe, and W. L. Farrar Interleukin 6 Supports the Maintenance of p53 Tumor Suppressor Gene Promoter Methylation Cancer Res., June 1, 2005; 65(11): 4673 - 4682. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Esfandiari, R. Green, R. F. Cotterman, I. P. Pogribny, S. J. James, and J. W. Miller Methyl deficiency causes reduction of the methyl-CpG-binding protein, MeCP2, in rat liver Carcinogenesis, December 1, 2003; 24(12): 1935 - 1940. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. D. Pham, N. K. MacLennan, C. T. Chiu, G. S. Laksana, J. L. Hsu, and R. H. Lane Uteroplacental insufficiency increases apoptosis and alters p53 gene methylation in the full-term IUGR rat kidney Am J Physiol Regulatory Integrative Comp Physiol, November 1, 2003; 285(5): R962 - R970. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. J. James, I. P. Pogribny, M. Pogribna, B. J. Miller, S. Jernigan, and S. Melnyk Mechanisms of DNA Damage, DNA Hypomethylation, and Tumor Progression in the Folate/Methyl-Deficient Rat Model of Hepatocarcinogenesis J. Nutr., November 1, 2003; 133(11): 3740S - 3747. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Satoh, T. Nakagawachi, H. Nakadate, Y. Kaneko, Z. Masaki, T. Mukai, and H. Soejima Significant Reduction of WT1 Gene Expression, Possibly Due to Epigenetic Alteration in Wilms' Tumor J. Biochem., March 1, 2003; 133(3): 303 - 308. [Abstract] [Full Text] [PDF] |
||||
![]() |
K.-J. Sohn, J. M. Stempak, S. Reid, S. Shirwadkar, J. B. Mason, and Y.-I. Kim The effect of dietary folate on genomic and p53-specific DNA methylation in rat colon Carcinogenesis, January 1, 2003; 24(1): 81 - 90. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. R. Karpf, B. C. Moore, T. O. Ririe, and D. A. Jones Activation of the p53 DNA Damage Response Pathway after Inhibition of DNA Methyltransferase by 5-Aza-2'-deoxycytidine Mol. Pharmacol., April 1, 2001; 59(4): 751 - 757. [Abstract] [Full Text] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Cancer Research | Clinical Cancer Research |
| Cancer Epidemiology Biomarkers & Prevention | Molecular Cancer Therapeutics |
| Molecular Cancer Research | Cancer Prevention Research |
| Cancer Prevention Journals Portal | Cancer Reviews Online |
| Annual Meeting Education Book | Meeting Abstracts Online |