Frequent inactivation of RUNX3 in endometrial carcinoma.
OBJECTIVE
Our objective was to determine whether RUNX3 tumor suppressor is inactivated in endometrial carcinoma.


METHODS
We have investigated 24 endometrial carcinomas, 3 endometrial carcinoma cell lines, and 9 normal endometria for genetic and epigenetic alterations of RUNX3. Reverse-transcription PCR (RT-PCR), methylation-specific PCR (MS-PCR) analysis, and loss of heterozygosity (LOH) analysis were performed. We also tested RUNX3 protein expression by immunohistochemistry.


RESULTS
Using RT-PCR technique, we observed a significant loss of RUNX3 mRNA expression in nine of 24 endometrial carcinomas (38%) and in all 3-cell lines (100%). In contrast, all nine of the normal endometria showed an abundant expression of RUNX3 mRNA. Methylation-specific PCR (MS-PCR) analysis of the CpG islands of RUNX3 showed the promoter region to be hypermethylated in 18 of 21 analyzed carcinomas (86%), whereas only two of nine normal endometria (22%) were methylated (p<0.01). By using two polymorphic microsatellite markers, D1S199 and D1S1676, we detected 1p36 LOH in 7 of 21 carcinomas (33%). We observed a significant relationship between the loss of RUNX3 mRNA expression and this regional LOH (p<0.01). Immunohistochemical staining showed that RUNX3 protein expression was lost in 12 of 21 endometrial carcinomas (57%). We observed a significantly more frequent loss of RUNX3 protein expression in the histologically higher-grade tumors (Grade 3) than in Grade 1 or 2 tumors (p<0.01).


CONCLUSIONS
These findings indicate that RUNX3 inactivation may play an important role in carcinogenesis of the endometrium, especially in high-grade endometrial carcinoma.
Department of Obstetrics and Gynecology, Osaka University Faculty of Medicine, Suita, Osaka, Japan.
Tatsuo
T
Yoshizaki
Takayuki
T
Enomoto
Masami
M
Fujita
Yutaka
Y
Ueda
Takashi
T
Miyatake
Kazuko
K
Fujiwara
Takahito
T
Miyake
Toshihiro
T
Kimura
Kiyoshi
K
Yoshino
Tadashi
T
Kimura
D045744:Cell Line, Tumor; D050677:Core Binding Factor Alpha 3 Subunit / Q000096:biosynthesis / Q000235:genetics*; D019175:DNA Methylation; D016889:Endometrial Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D016147:Genes, Tumor Suppressor; D006801:Humans; D007150:Immunohistochemistry; D019656:Loss of Heterozygosity; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D050677:Core Binding Factor Alpha 3 Subunit; D012333:RNA, Messenger; C493729:Runx3 protein, human