Intestinal Tumorigenesis (intestinal + tumorigenesi)

Distribution by Scientific Domains

Selected Abstracts

SAP-1 is a microvillus-specific protein tyrosine phosphatase that modulates intestinal tumorigenesis

GENES TO CELLS, Issue 3 2009
Hisanobu Sadakata
SAP-1 (PTPRH) is a receptor-type protein tyrosine phosphatase (RPTP) with a single catalytic domain in its cytoplasmic region and fibronectin type III-like domains in its extracellular region. The cellular localization and biological functions of this RPTP have remained unknown, however. We now show that mouse SAP-1 mRNA is largely restricted to the gastrointestinal tract and that SAP-1 protein localizes to the microvilli of the brush border in gastrointestinal epithelial cells. The expression of SAP-1 in mouse intestine is minimal during embryonic development but increases markedly after birth. SAP-1-deficient mice manifested no marked changes in morphology of the intestinal epithelium. In contrast, SAP-1 ablation inhibited tumorigenesis in mice with a heterozygous mutation of the adenomatous polyposis coli gene. These results thus suggest that SAP-1 is a microvillus-specific RPTP that regulates intestinal tumorigenesis. [source]

The role of NO synthases in arginine-dependent small intestinal and colonic carcinogenesis

Hagit F. Yerushalmi
Abstract Arginine is catabolized by NOS2 and other nitric oxide synthases to form nitric oxide. We evaluated the roles of dietary arginine and Nos2 in Apc -dependent intestinal tumorigenesis in Min mice with and without a functional Nos2 gene. NOS2 protein was expressed only in intestinal tissues of ApcMin/+Nos2+/+ mice. NOS3 expression was higher in intestinal tissues of mice lacking Nos2, mainly in the small intestine. When diet was supplemented with arginine (0.2% and 2% in drinking water), lack of Nos2 results in decreased tumorigenesis in both small intestine and colon. In Nos2 knockout mice, supplemental arginine (up to 2%) caused a decrease in small intestinal tumor number and size. The arginine-dependent decrease was associated with an increase in nitrotyrosine formation and apoptosis in the region of intestinal stem cells. Mice expressing Nos2 did not show these changes. These mice did, however, show an arginine-dependent increase in colon tumor number and incidence, while no effect on apoptosis was seen. These changes were associated with increased nitrotyrosine formation in epithelial cells. Mice lacking Nos2 did not show changes in tumorigenesis or nitrotyrosine formation, while demonstrating an arginine-dependent increase in apoptosis. These data suggest that Nos2 and dietary arginine have significant effects on intestinal and colonic tumorigenesis in Min mice. In both tissues, loss of Nos2 is associated with decreased tumorigenesis when mice are supplemented with dietary arginine. In the small intestine, Nos2 prevents the arginine-induced decrease in tumor number and size, which is associated with NOS3 expression and increased apoptosis. In the colon, Nos2 is required for the arginine-induced increase in tumor number and incidence. 2005 Wiley-Liss, Inc. [source]

Expression of Pla2g2a prevents carcinogenesis in Muc2 -deficient mice

CANCER SCIENCE, Issue 11 2008
R. J. A. Fijneman
Goblet cell depletion and down-regulation of MUC2 expression are observed in a significant percentage of human non-mucinous colorectal adenocarcinomas. Direct evidence for the role of MUC2 in gastrointestinal tumor formation was demonstrated by a knockout of Muc2 in mice that resulted in the development of adenocarcinomas in the small and large intestine. The secretory phospholipase Pla2g2a is a protein that confers resistance to ApcMin/+ -induced intestinal tumorigenesis. Like Muc2, in the large intestine Pla2g2a is exclusively expressed by the goblet cells and Pla2g2a's tumor resistance is also strongest in the large intestine. Possible genetic interactions between Muc2 and Pla2g2a were examined by creating C57BL/6- Muc2,/,Pla2g2a transgenic mice. Expression of a Pla2g2a transgene reduced tumorigenesis in the large intestine by 90% in male Muc2,/, mice and by nearly 100% in female Muc2,/, mice. Expression of Pla2g2a also inhibited tumor progression. Microarray gene expression studies revealed Pla2g2a target genes that modulate intestinal energy metabolism, differentiation, inflammation, immune responses and proliferation. Overall, results of the present study demonstrate an Apc-independent role for Pla2g2a in tumor resistance and indicate that Pla2g2a plays an important role, along with Muc2, in protection of the intestinal mucosa. (Cancer Sci 2008; 99: 2113,2119) [source]