Immunoprecipitation of nucleosomal DNA is a novel procedure to improve the sensitivity of serum screening for the p16 hypermethylation associated with colon cancer.
BACKGROUND
We developed a novel method of methylation-specific PCR (MSP) using immunoprecipitation with anti-histone antibody (IP-MSP) to efficiently detect serum methylated DNA tightly bound to de-acetylated histones.


METHODS
The detection limit of IP-MSP for p16 methylation was determined with a standard made by cell line (SKCO-1) lysate. p16 methylation of tumor and/or serum of 51 colorectal cancers and 10 adenoma patients, and 10 healthy volunteers was detected with conventional MSP or IP-MSP.


RESULTS
IP-MSP detected p16 methylation from 0.5pg/mul of the cell lysate. The sensitivity of IP-MSP for detecting serum p16 methylation in 27 patients with tumors characterized by p16 methylation was significantly higher than that with conventional method (81% versus 59%), particularly in Stage II patients (91% versus 45%). IP-MSP detected no p16 hypermethylation in sera of adenoma patients and volunteers.


CONCLUSIONS
IP-MSP is thus considered to be a promising procedure to detect serum methylated DNA in colorectal cancer patients.
Division of Gastroenterology and Hematology/Oncology, Department of Medicine, Asahikawa Medical College, 2-1-1-1, Midorigaoka-Higashi, Asahikawa, Hokkaido 078-8510, Japan.
Jun
J
Sakamoto
Mikihiro
M
Fujiya
Kotaro
K
Okamoto
Toshie
T
Nata
Yuhei
Y
Inaba
Kentaro
K
Moriichi
Hiroki
H
Tanabe
Yusuke
Y
Mizukami
Jiro
J
Watari
Toshifumi
T
Ashida
Yutaka
Y
Kohgo
D014408:Biomarkers, Tumor / Q000097:blood / Q000235:genetics; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000097:blood / Q000737:chemistry / Q000235:genetics*; D004247:DNA / Q000235:genetics; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000097:blood* / Q000235:genetics; D005260:Female; D019942:Genes, p16; D006801:Humans; D047468:Immunoprecipitation; D008297:Male; D009707:Nucleosomes / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods; D011401:Promoter Regions, Genetic
D014408:Biomarkers, Tumor; D004273:DNA, Neoplasm; D009707:Nucleosomes; D004247:DNA