A flourescence based assay for secreted PLA2 activity reveals diversity in the intestinal tract of inbred mouse strains

5125 The secreted type II nonpancreatic phospholipase A2 (Pla2g2a) gene was previously identified as a modifier of intestinal adenoma multiplicity in Apc Min/+ mice. To determine if intestinal secreted phospholipase A2 (sPLA 2 ) activity was also attenuated in susceptible strains, we developed a sensitive assay to characterize sPLA 2 activity utilizing a fluorescent BODIPY-labeled phospholipid substrate. Here we report assay conditions that can distinguish between secreted and cytosolic PLA 2 enzyme activities in extract of intestinal tissue. The small intestine of wildtype mice exhibited higher activity levels than the large intestine. Consistent with predictions from the Pla2g2a gene sequence from inbred strains, we detected low levels of enzyme activity in inbred strains containing Pla2g2a mutations; these strains were also associated with greater numbers of intestinal polyps. In contrast, the assay was able to distinguish differences in levels of secretory PLA 2 activity between neoplasia-resistant strains which carry wildtype Pla2g2a alleles. Immunohistochemical analyses of intestinal tissues were consistent with activity levels. This studies will further our understanding of the role of Pla2g2a in the development of intestinal and colorectal tumorigenesis in both mice and humans. Research supported in part by NIH grant RO1 DK60369 to SAF and NCI grant PO1 CA72027 and CA89560 to LDS and AMB.