Carcinogenesis Advance Access originally published online on February 6, 2008
Carcinogenesis 2008 29(4):824-829; doi:10.1093/carcin/bgn028
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Plasminogen activator inhibitor-1 (Pai-1) blockers suppress intestinal polyp formation in Min mice
Cancer Prevention Basic Research Project, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
1 Shizuoka Coffein Co. Ltd, 129 Suidocho, Shizuoka-shi 420-0008, Japan
* To whom correspondence should be addressed. Tel: +81 3 3542 2511; Fax: +81 3 3543 9305;Email: mimutoh{at}gan2.ncc.go.jp
Obesity and hyperlipidemia are known to increase colorectal tumor risk. We noticed that Min mice, featuring a defect in the adenomatous polyposis coli (Apc) gene, develop intestinal polyps along with high serum triglyceride (TG) levels up to 10-fold those observed in wild-type mice. In these mice, messenger RNA (mRNA) expression of lipoprotein lipase, which catalyzes hydrolysis of TG, is downregulated. In the present study, we focused on adipocytokines, especially plasminogen activator inhibitor-1 (Pai-1), which is involved in hyperlipidemic status and may promote intestinal polyp formation in Min mice. Serum Pai-1 levels in the 15-week-old male Min mice were eight times higher than in wild-type mice and hepatic Pai-1 mRNA levels were 11-fold increased. In addition, Pai-1 immunostaining was strong in small intestinal epithelial cells of Min mice. Administration of a PAI-1 inhibitor, SK-216, at 25, 50 and 100 p.p.m. doses in the diet for 9 weeks reduced serum Pai-1 levels and hepatic Pai-1 mRNA levels of Min mice to the wild-type levels. Moreover, SK-216 at 50 and 100 p.p.m. significantly reduced total numbers of intestinal polyps to 64 and 56% of the untreated group value, respectively. Serum TG levels were also decreased by 43% at the dose of 100 p.p.m. Administration of 50 p.p.m. SK-116, another PAI-1 inhibitor, for 9 weeks similarly reduced serum Pai-1 levels and total numbers of intestinal polyps to 70% of the untreated group value. These results indicate that Pai-1 induction associated with hypertriglyceridemia may contribute to intestinal polyp formation with Apc deficiency, and PAI-1 could thus be a novel target for colorectal chemopreventive agents.
Abbreviations: Ab, antibody; APC, adenomatous polyposis coli; LPL, lipoprotein lipase; mRNA, messenger RNA; Pai-1, plasminogen activator inhibitor-1; PCR, polymerase chain reaction; RT, reverse transcription; TG, triglyceride
Received August 10, 2007; revised January 23, 2008; accepted January 23, 2008.