TY - JOUR
T1 - Colorectal cancer with mutation in BRAF, KRAS, and wild-type with respect to both oncogenes showing different patterns of DNA methylation
AU - Nagasaka, Takeshi
AU - Sasamoto, Hiromi
AU - Notohara, Kenji
AU - Cullings, Harry M.
AU - Takeda, Masanori
AU - Kimura, Keigo
AU - Kambara, Takeshi
AU - MacPhee, Donald G.
AU - Young, Joanne
AU - Leggett, Barbara A.
AU - Jass, Jeremy R.
AU - Tanaka, Noriaki
AU - Matsubara, Nagahide
PY - 2004
Y1 - 2004
N2 - Purpose: BRAF mutations are common in sporadic colorectal cancers (CRCs) with a DNA mismatch repair (MMR) deficiency that results from promoter methylation of hMLH1. whereas KRAS mutations are common in MMR proficient CRCs associated with promoter methylation of MGMT. The aim of this study was to further investigate the link between genetic alterations in the RAS/RAF/ERK pathway and an underlying epigenetic disorder. Patients and Methods: Activating mutations of BRAF and KRAS were identified and correlated with promoter methylation of 11 loci, including MINT1, MINT2, MINT31, CACNA1G, p16 INK4a, p14ARF, COX2, DAPK, MGMT, and the two regions in hMLH1 in 468 CRCs and matched normal mucosa. Results: BRAF V599E mutations were identified in 21 (9%) of 234 CRCs, and KRAS mutations were identified in 72 (31%) of 234 CRCs. Mutations in BRAF and KRAS were never found in the same tumor. CRCs with BRAF mutations showed high-level promoter methylation in multiple loci, with a mean number of methylated loci of 7.2 (95% CI, 6.6 to 7.9) among 11 loci examined (P < .0001). Tumors with KRAS mutations showed low-level promoter methylation, and CRCs with neither mutation showed a weak association with promoter methylation, with an average number of methylated loci of 1.8 (95% CI, 1.5 to 2.1) and 1.0 (95% CI, 0.79 to 1.3), respectively. Conclusion: In CRC, the methylation status of multiple promoters can be predicted through knowledge of BRAF and, to a lesser extent, KRAS activating mutations, indicating that these mutations are closely associated with different patterns of DNA hypermethylation. These changes may be important events in colorectal tumorigenesis.
AB - Purpose: BRAF mutations are common in sporadic colorectal cancers (CRCs) with a DNA mismatch repair (MMR) deficiency that results from promoter methylation of hMLH1. whereas KRAS mutations are common in MMR proficient CRCs associated with promoter methylation of MGMT. The aim of this study was to further investigate the link between genetic alterations in the RAS/RAF/ERK pathway and an underlying epigenetic disorder. Patients and Methods: Activating mutations of BRAF and KRAS were identified and correlated with promoter methylation of 11 loci, including MINT1, MINT2, MINT31, CACNA1G, p16 INK4a, p14ARF, COX2, DAPK, MGMT, and the two regions in hMLH1 in 468 CRCs and matched normal mucosa. Results: BRAF V599E mutations were identified in 21 (9%) of 234 CRCs, and KRAS mutations were identified in 72 (31%) of 234 CRCs. Mutations in BRAF and KRAS were never found in the same tumor. CRCs with BRAF mutations showed high-level promoter methylation in multiple loci, with a mean number of methylated loci of 7.2 (95% CI, 6.6 to 7.9) among 11 loci examined (P < .0001). Tumors with KRAS mutations showed low-level promoter methylation, and CRCs with neither mutation showed a weak association with promoter methylation, with an average number of methylated loci of 1.8 (95% CI, 1.5 to 2.1) and 1.0 (95% CI, 0.79 to 1.3), respectively. Conclusion: In CRC, the methylation status of multiple promoters can be predicted through knowledge of BRAF and, to a lesser extent, KRAS activating mutations, indicating that these mutations are closely associated with different patterns of DNA hypermethylation. These changes may be important events in colorectal tumorigenesis.
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U2 - 10.1200/JCO.2004.02.154
DO - 10.1200/JCO.2004.02.154
M3 - Article
C2 - 15542810
AN - SCOPUS:16544363110
VL - 22
SP - 4584
EP - 4594
JO - Journal of Clinical Oncology
JF - Journal of Clinical Oncology
SN - 0732-183X
IS - 22
ER -