Both BRAF and KRAS mutations are rare in colorectal carcinomas from patients with hereditary nonpolyposis colorectal cancer.
The BRAF mutations have been suggested to be linked with defective mismatch repair in colorectal carcinomas. To clarify the extent of BRAF mutations in HNPCC colorectal carcinomas, which are typical mismatch repair deficient carcinomas, we compared the frequency of BRAF mutations between HNPCC, familial adenomatous polyposis (FAP) and sporadic cases. The frequency of KRAS mutations was also compared between these three syndromes. No BRAF mutations were detected in 33 HNPCC colorectal carcinomas, while they were detected in 3 of 26 (12%) FAP carcinomas and 2 of 53 (4%) microsatellite stable sporadic carcinomas. KRAS mutations were detected in 2 of 33 (6%) HNPCC, 9 of 26 (35%) FAP and 18 of 53 (34%) sporadic carcinomas. Such extremely low frequencies of BRAF and KRAS mutations in HNPCC colorectal carcinomas suggest that the participation of RAS-RAF signaling is minor in HNPCC, and that the previously suggested high frequency of BRAF mutations in mismatch repair deficient colorectal carcinomas is not due to mutations of mismatch repair genes.
Miyaki
Michiko
M
Department Surgery, Tokyo Metropolitan Komagome Hospital, 3-18-22 Honkomagome, Bunkyo-ku, Tokyo 113-8677, Japan. mmiyaki@opal.famille.ne.jp
Iijima
Takeru
T
Yamaguchi
Tatsuro
T
Kadofuku
Tsuyoki
T
Funata
Nobuaki
N
Mori
Takeo
T
D011125:Adenomatous Polyposis Coli / Q000235:genetics; D020137:Base Pair Mismatch; D002277:Carcinoma / Q000235:genetics*; D015179:Colorectal Neoplasms; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics*; D006801:Humans; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D048493:Proto-Oncogene Proteins B-raf; D019908:Proto-Oncogene Proteins c-raf / Q000235:genetics*; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins
C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D019908:Proto-Oncogene Proteins c-raf; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins