Novel methylation panel for the early detection of colorectal tumors in stool DNA.
BACKGROUND
Previous studies showed that the assessment of promoter hypermethylation of a limited number of genes in tumor biopsies may identify the majority of colorectal tumors. This study aimed to assess the clinical usefulness of a panel of methylation biomarkers in stool DNA in the identification of colorectal tumors, using methylation-specific melting curve analysis (MS-MCA), a technique that simultaneously analyzes all cytosine-phosphate-guanine (CpG) residues within a promoter.


METHODS
The promoter methylation status of 4 tumor-related genes (RARB2, p16INK4a, MGMT, and APC) was analyzed in DNA stool samples and corresponding tissues in an initial set of 12 patients with newly diagnosed primary colorectal carcinomas and 20 patients with newly diagnosed colorectal adenomas, using methylation-specific polymerase chain reaction. Results were replicated in a set of 82 patients (20 healthy subjects, 16 patients with inflammatory bowel disease (IBD), 20 patients with adenomas, and 26 patients with carcinomas), using MS-MCA analyses.


RESULTS
In the initial set, >or= 1 positive methylation marker was detected in the stools of 9 of 12 patients (75%) with carcinomas and 12 of 20 patients (60%) with adenomas, with no false-positive results. Stool analyses missed 7 methylated lesions (25%). In the replication set, stool DNA testing detected 16 of 26 carcinomas (62%) and 8 of 20 adenomas (40%). The MS-MCAs missed 14 methylated tumors (37%). No aberrant methylation was evident in healthy subjects, but the RARB2 marker was positive in 2 of 15 stool samples (13%) of patients with IBD.


CONCLUSIONS
Analysis via MS-MCA of a panel of methylation markers in stool DNA may offer a good alternative in the early, noninvasive detection of colorectal tumors.
Azuara
Daniel
D
Translational Research Laboratory, Institut Català d'Oncologia-IDIBELL, Barcelona, Spain.
Rodriguez-Moranta
Francisco
F
de Oca
Javier
J
Soriano-Izquierdo
Antonio
A
Mora
Josefina
J
Guardiola
Jordi
J
Biondo
Sebastiano
S
Blanco
Ignacio
I
Peinado
Miguel Angel
MA
Moreno
Victor
V
Esteller
Manel
M
Capellá
Gabriel
G
D000230:Adenocarcinoma / Q000175:diagnosis / Q000235:genetics; D000236:Adenoma / Q000175:diagnosis / Q000235:genetics; D014408:Biomarkers, Tumor / Q000032:analysis* / Q000235:genetics; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000235:genetics; D004247:DNA / Q000032:analysis / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics*; D015254:DNA Modification Methylases / Q000235:genetics; D045643:DNA Repair Enzymes / Q000235:genetics; D055088:Early Detection of Cancer / Q000379:methods*; D005243:Feces / Q000737:chemistry*; D005260:Female; D017491:Genes, APC; D019942:Genes, p16; D006801:Humans; D008297:Male; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D018168:Receptors, Retinoic Acid / Q000235:genetics; D012680:Sensitivity and Specificity; D025521:Tumor Suppressor Proteins / Q000235:genetics
D014408:Biomarkers, Tumor; C533416:RARB2 protein, human; D018168:Receptors, Retinoic Acid; D025521:Tumor Suppressor Proteins; D004247:DNA; D015254:DNA Modification Methylases; C515491:MGMT protein, human; D045643:DNA Repair Enzymes