BRAF, K-ras and BAT26 mutations in colorectal polyps and stool.
OBJECTIVE
To assess the feasibility of using BRAF, K-ras and BAT26 genes as stool-based molecular markers for detection of colorectal adenomas and hyperplastic polyps (HPs).


METHODS
We applied PCR-SSCP and direct sequencing to detect BRAF mutations of polyps and paired stool samples. Primer-mediated restriction fragment length polymorphism (RFLP) analysis and mutant-enriched PCR were used in detection of K-ras mutations of polyp tissues and paired stool samples respectively. BAT26, a microsatellite instability marker was examined by detection of small unstable alleles in a poly (A) repeat.


RESULTS
No genetic alterations were detected in the 36 colonoscopically normal patients in either tissues or stools. BRAF, K-ras and BAT26 mutations were found in 4 (16%), 10 (40%) and 3 (12%) of 25 adenoma tissues and among them, 75%, 80% and 100% of patients were observed to contain the same mutations in their corresponding stool samples. In HPs, mutations of BRAF and K-ras were detected in the tumor DNA of 2 (11.1%) and 8 (33.3%) of 18 patients respectively, all of whom had identical alterations in their stools. Taken together, the three genetic markers detected 15 (60%) of 25 adenomas and 8 (44.4%) of 18 HPs. The sensitivity of stool detection was 80% for adenomas and 100% for HPs with an overall specificity of 92% for adenomas and 100% for HPs.


CONCLUSIONS
BRAF, K-ras and BAT26 genes have the potential to be molecular markers for colorectal adenomas and HPs, and can be used as non-invasive screening markers for colorectal polyps.
Jin
Ying-Min
YM
Department of Gastroenterology, Second Affiliated Hospital of Harbin Medical University, Harbin 150086, Heilongjiang Province, China.
Li
Bao-Jie
BJ
Qu
Bo
B
Du
Ya-Ju
YJ
D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000096:biosynthesis* / Q000235:genetics; D003111:Colonic Polyps / Q000378:metabolism*; D005243:Feces; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D011905:Genes, ras / Q000235:genetics*; D005819:Genetic Markers; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D009154:Mutation; D012150:Polymorphism, Restriction Fragment Length; D048493:Proto-Oncogene Proteins B-raf / Q000096:biosynthesis* / Q000235:genetics*; D018631:ras Proteins / Q000096:biosynthesis*
C516892:BAT26 microsatellite DNA; D014408:Biomarkers, Tumor; D005819:Genetic Markers; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D018631:ras Proteins