Possible involvement of RUNX3 silencing in the peritoneal metastases of gastric cancers.
OBJECTIVE
Our previous results suggested that a lack of RUNX3 function contributed to human gastric carcinogenesis, but the role of RUNX3 in progression and metastasis remains unclear. We examined RUNX3 expression in clinical samples of peritoneal metastases in gastric cancers. Changes in metastatic potential were assessed in animal experiments using stable RUNX3 transfectants of gastric cancer cells. Finally, global expression changes were analyzed using a cDNA microarray.


RESULTS
Significant down-regulation of RUNX3 through methylation on the promoter region was observed in primary tumors (75%) as well as in all clinical peritoneal metastases of gastric cancers (100%) compared with normal gastric mucosa. Stable transfection of RUNX3 inhibited cell proliferation slightly, and modest transforming growth factor-beta (TGF-beta)-induced antiproliferative and apoptotic effects were observed. Interestingly, it strongly inhibited peritoneal metastases of gastric cancers in animal model (P < 0.01). Furthermore, we did globally analyzed expression profiles of approximately 21,000 genes in parent cells and stable transfectant of RUNX3 using a cDNA microarray. Microarray analysis identified approximately 28 candidate genes under the possible downstream control of RUNX3, some of these genes were considered to be possibly involved in peritoneal metastases, which were related to signal transduction (vav3, TOLL-like receptor, MAPKK, MET, S1 00A1 1, and cathepsin E), apoptosis (caspase 9), immune responses (CD55 and TLR1O), and cell adhesion (sialyltransferase 1 and galectin 4). Some of the genes are involved in the TGF-beta signaling pathway.


CONCLUSIONS
These results indicate that silencing of RUNX3 affects expression of important genes involved in aspects of metastasis including cell adhesion, proliferation, apoptosis, and promoting the peritoneal metastasis of gastric cancer. Identification of such genes could suggest new therapeutic modalities and therapeutic targets.
Sakakura
Chouhei
C
Surgery and Regenerative Medicine, Kyoto Prefectural University of Medicine, Japan. sakakura@koto.kpu-m.ac.jp
Hasegawa
Kazunori
K
Miyagawa
Koji
K
Nakashima
Susumu
S
Yoshikawa
Tetsuji
T
Kin
Shuichi
S
Nakase
Yuenn
Y
Yazumi
Shujiro
S
Yamagishi
Hisakazu
H
Okanoue
Takeshi
T
Chiba
Tsutomu
T
Hagiwara
Akeo
A
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001483:Base Sequence; D015152:Blotting, Northern; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D050677:Core Binding Factor Alpha 3 Subunit; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000235:genetics*; D015536:Down-Regulation / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics; D020868:Gene Silencing / Q000502:physiology*; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D008969:Molecular Sequence Data; D009368:Neoplasm Transplantation; D009374:Neoplasms, Experimental / Q000235:genetics / Q000473:pathology; D020411:Oligonucleotide Array Sequence Analysis; D010534:Peritoneal Neoplasms / Q000235:genetics / Q000556:secondary*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid; D013274:Stomach Neoplasms / Q000235:genetics / Q000473:pathology*; D014157:Transcription Factors / Q000235:genetics*; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D053773:Transforming Growth Factor beta1; D014183:Transplantation, Heterologous; D015854:Up-Regulation / Q000235:genetics
D050677:Core Binding Factor Alpha 3 Subunit; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; C493729:Runx3 protein, human; C493730:Runx3 protein, mouse; C508960:TGFB1 protein, human; C508961:Tgfb1 protein, mouse; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1