DNA methylation abnormalities, including widespread hypomethylation and regional areas of hypermethylation, are a consistent molecular feature of human neoplastic cells. These changes, particularly hypermethylation, potentially alter chromatin structure and could be major factor in the accrual of genetic instability events which drive tumor progression. The hypermethylation may result from abnormal expression of the DNA-methyl transferase (DNA-MT) gene. We have cloned a portion of the human DNA-MT gene and find that its expression is dramatically increased, at the steady- state transcript level, in established lines of multiple types of human cancer cells. DNA-MT gene expression is coupled to DNA synthesis, and rises sharply during DNA replication prior to cell division. The present proposal will evaluate DNA-MT gene expression as a marker for the earliest events in the evolution of human colon cancer. Our initial studies reveal exponential increases in DNA-MT transcript levels for each stage of colon cancer progression, including increased levels in histologically normal appearing colonic mucosa distant from pre-malignant adenomatous polyps and cancers. We will determine, using PCR and cytochemical techniques, whether sequential increases in DNA MT transcript levels can: (a) define genetic predisposition states to colon cancer developments including those underlying the common forms of colon cancer; (b) define prognostic parameters for progression of pre-malignant adenomatous polyps and prediction of colon cancer metastatic potential; and (c) identify the cellular changes underlying evolution of colon cancer in a rodent carcinogenesis model. Positive findings in the above studies may lead, in future work, to similar evaluation of other major cancers including bladder, prostate, cervical, breast and lung.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA054396-04
Application #
2095891
Study Section
Pathology B Study Section (PTHB)
Project Start
1991-04-01
Project End
1996-03-31
Budget Start
1994-04-01
Budget End
1995-03-31
Support Year
4
Fiscal Year
1994
Total Cost
Indirect Cost
Name
Johns Hopkins University
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
045911138
City
Baltimore
State
MD
Country
United States
Zip Code
21218
Bachman, Kurtis E; Park, Ben Ho; Rhee, Ina et al. (2003) Histone modifications and silencing prior to DNA methylation of a tumor suppressor gene. Cancer Cell 3:89-95
Baylin, Stephen B (2002) Mechanisms underlying epigenetically mediated gene silencing in cancer. Semin Cancer Biol 12:331-7
Esteller, M; Cordon-Cardo, C; Corn, P G et al. (2001) p14ARF silencing by promoter hypermethylation mediates abnormal intracellular localization of MDM2. Cancer Res 61:2816-21
Esteller, M; Corn, P G; Baylin, S B et al. (2001) A gene hypermethylation profile of human cancer. Cancer Res 61:3225-9
Esteller, M; Risques, R A; Toyota, M et al. (2001) Promoter hypermethylation of the DNA repair gene O(6)-methylguanine-DNA methyltransferase is associated with the presence of G:C to A:T transition mutations in p53 in human colorectal tumorigenesis. Cancer Res 61:4689-92
Rountree, M R; Bachman, K E; Baylin, S B (2000) DNMT1 binds HDAC2 and a new co-repressor, DMAP1, to form a complex at replication foci. Nat Genet 25:269-77
Esteller, M; Sparks, A; Toyota, M et al. (2000) Analysis of adenomatous polyposis coli promoter hypermethylation in human cancer. Cancer Res 60:4366-71
Baylin, S B; Herman, J G (2000) DNA hypermethylation in tumorigenesis: epigenetics joins genetics. Trends Genet 16:168-74
Esteller, M; Tortola, S; Toyota, M et al. (2000) Hypermethylation-associated inactivation of p14(ARF) is independent of p16(INK4a) methylation and p53 mutational status. Cancer Res 60:129-33
Toyota, M; Ho, C; Ahuja, N et al. (1999) Identification of differentially methylated sequences in colorectal cancer by methylated CpG island amplification. Cancer Res 59:2307-12

Showing the most recent 10 out of 20 publications