BRAF mutation in endometrial carcinoma and hyperplasia: correlation with KRAS and p53 mutations and mismatch repair protein expression.
OBJECTIVE
Although several gene abnormalities have been reported in endometrial carcinoma, the genetic alterations have not fully been elucidated. Recent studies have revealed frequent activating mutations of the gene for BRAF, an effector of Ras protein in the mitogen-activated protein kinase pathway, in several malignancies. However, the prevalence and significance of BRAF mutations in endometrial carcinoma remain unclear.


METHODS
We examined BRAF mutations in exons 11 and 15 in 97 cases of endometrial carcinoma (endometrioid type, 78; nonendometrioid type, 19), 9 cases of atypical endometrial hyperplasia, and 20 cases of normal endometrium by direct sequencing. In addition, mutations of KRAS and p53 and the immunohistochemical expression of hMLH1 and hMSH2 were also examined.


RESULTS
Of the 97 carcinomas and 9 hyperplasias, 20 (21%) and 1 (11%) had BRAF mutations, most of them at previously unreported sites. Twenty samples of normal endometrium and 21 samples of normal endometrium obtained from sites adjacent to neoplastic lesions had no BRAF mutations. There was no apparent difference in the prevalence of BRAF mutation among stages, histologic subtypes, or grades. Mutations of KRAS and p53 were found in 18 (19%) and 22 (23%) cases, and 65 (67%) and 92 (95%) cases showed positive immunostaining for hMLH1 and hMSH2, respectively. BRAF mutation was more frequently found in hMLH1-negative cases (12 of 32, 41%) than in hMLH1-positive cases (7 of 65, 11%; P = 0.008), suggesting that it is associated with an abnormal mismatch repair function.


CONCLUSIONS
These findings suggest that mutations of the BRAF gene are partly involved in the malignant transformation of the endometrium.
Feng
Yu-Zhen
YZ
Department of Obstetrics and Gynecology, Shinshu University School of Medicine, Asahi, Matsumoto, Japan.
Shiozawa
Tanri
T
Miyamoto
Tsutomu
T
Kashima
Hiroyasu
H
Kurai
Miyuki
M
Suzuki
Akihisa
A
Konishi
Ikuo
I
D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D000368:Aged; D002352:Carrier Proteins; D004252:DNA Mutational Analysis; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D004714:Endometrial Hyperplasia / Q000235:genetics*; D016889:Endometrial Neoplasms / Q000235:genetics*; D004717:Endometrium / Q000502:physiology; D005260:Female; D011905:Genes, ras / Q000502:physiology; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D009154:Mutation / Q000235:genetics*; D009363:Neoplasm Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics*
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein