Background & Aims: Inflammatory bowel conditions, particularly ulcerative c
olitis, are associated with an increased incidence of neoplastic transforma
tion. High levels of proinflammatory leukotrienes (LTs)and upregulated expr
ession of cyclooxygenase (COX)-2 are characteristic of inflammation. Moreov
er, COX-2 has been implicated in cell survival and early colon carcinogenes
is, Other aspects of interest for intestinal cell viability are the levels
of beta-catenin and the antiapoptotic protein Bcl-2. We investigated the po
ssibility that LTs participate in the regulation of these survival factors.
Methods: We used the human intestinal epithelial cell line Int 407 and the
vat intestinal epithelial cell line IEC-6. immunoblotting was applied to a
scertain protein expression and distribution, and enzyme immunoassay method
ology was used to measure prostaglandin E-2 (PGE,) production. Apoptotic ab
ility was assessed by trypan blue exclusion, Hoechst staining, DNA fragment
ation, and a caspase-3 activity assay. Results: LTD4 and LTB4, but not LTC4
, caused a time- and dose-dependent increase in expression and/or membrane
accumulation of COX-2, beta-catenin, and Bcl-2, as well as PGE(2) productio
n, Apoptosis assays showed that the effects of LTs on these transformation-
associated proteins correlated well with the ability of these LTs to reduce
programmed cell death, Conclusions: The results suggest that inflammatory
conditions are associated with the expression and distribution of proteins
that are characteristic of transformed cells; such conditions may involve a
signaling mechanism comprising an altered rate of apoptosis.