Although both preclinical and clinical studies continue to document the chemopreventive activity of the nonsteroidal anti-inflammatory drug FGN-1 (Aptosyn, exisulind), its mechanism of action remains unclear. The hypothesis of the proposed experimentation is that FGN-1 induces apoptosis by decreasing both nuclear levels of beta-catenin and the transcriptional activation of downstream targets of the APC/beta-catenin pathway. The rationale for this hypothesis is provided by previous studies, which indicate that FGN-1 lacks cyclooxygenase inhibitory activity and induces apoptosis independent of p53, bcl-2, cell cycle arrest and decreased cell proliferation. The ability of FGN-1 to induce apoptosis in human colonic adenomas harboring mutations in the adenomatous polyposis coli (APC)gene when combined with the reported role of APC in apoptosis suggests that FGN-1 may restore the activity of a malfunctioned APC/beta-catenin pathway. Data from preliminary studies support this hypothesis and indicate that FGN-1 decreases both levels of nuclear beta-catenin and the expression of cyclin Dl, a downstream target of the APC/beta-catenin pathway, in cells with mutant APC. All experimentation will focus on colon carcinogenesis, where the role of APC has been investigated extensively and the antitumor activity of FGN-l has been well documented.
In Aim 1, a unique strain of multiple intestinal neoplasia (Min) mice, bearing a mutation in the APC gene, will be utilized to evaluate the chemopreventive activity of FGN-l analogs (i.e., CP248), which may be more efficacious than the parent compound in inhibiting colon tumor formation. Drug-induced changes in the expression and interaction of APC,beta-catenin, Axin and GSK3beta, the phosphorylation of beta-catenin, and the expression of downstream targets of the APC/beta-catenin pathway will be systematically evaluated in Aim 2, using both colorectal tissues from Minmice and human colon carcinoma cell lines with defined mutations in APC and beta-catenin.
In Aim 3, the ability of FGN-l/CP248 to modulate beta-catenin-regulated transcription will be confirmed using a Tcf reporter assay. These findings will be translated to a clinical setting in Aim 4, where the cellular distribution of beta-catenin will be examined in colon tissues from FAP patients before and after FGN-I administration. It is anticipated that the proposed preclinical experimentation will not only enhance our current understanding of the role of APC in apoptosis, but contribute to both the establishment of biomarkers of FGN-1 activity and the identification of novel cellular targets for chemopreventive intervention.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA082624-03
Application #
6633483
Study Section
Metabolic Pathology Study Section (MEP)
Program Officer
Crowell, James A
Project Start
2001-04-01
Project End
2005-03-31
Budget Start
2003-04-01
Budget End
2004-03-31
Support Year
3
Fiscal Year
2003
Total Cost
$313,740
Indirect Cost
Name
Fox Chase Cancer Center
Department
Type
DUNS #
073724262
City
Philadelphia
State
PA
Country
United States
Zip Code
19111
Chang, Wen-Chi L; Everley, Lynette C; Pfeiffer 2nd, Gordon R et al. (2005) Sulindac sulfone is most effective in modulating beta-catenin-mediated transcription in cells with mutant APC. Ann N Y Acad Sci 1059:41-55
Clapper, Margie L; Coudry, Jacques; Chang, Wen-Chi L (2004) beta-catenin-mediated signaling: a molecular target for early chemopreventive intervention. Mutat Res 555:97-105
Clapper, M L; Chang, W C; Meropol, N J (2001) Chemoprevention of colorectal cancer. Curr Opin Oncol 13:307-13