Abstract 959: Sulindac resistant colon tumors possess an altered molecular phenotype

Abstract

Abstract Although non-steroidal anti-inflammatory drugs (NSAIDs), including sulindac, have been used extensively as chemopreventive agents for colorectal cancer (CRC), results are not consistent. NSAIDs, most reportedly sulindac, often do not cause a complete regression of adenomas and some patients develop resistance to NSAID treatment. In this study we evaluated the effect of sulindac on colon tumorigenesis in the ApcMin/+ mouse model. Sulindac (180 ppm) given in drinking water for 9 weeks to ApcMin/+ mice significantly reduced the size of colon tumors, but actually caused an increase in colon tumor multiplicity relative to untreated controls (average of 5.5 vs. 1.6 tumors/mouse, respectively; P<0.0001). This indicated that the drug could inhibit colon tumor progression but not initiation. In the small intestine, sulindac significantly reduced tumor size and multiplicity relative to untreated controls (average of 2.3 vs. 42.0 tumors/mouse, respectively; P<0.0001). Generation of a panel of prostanoids was comparably suppressed in the small intestine and colon by sulindac treatment. Sulindac is also known to have many non-COX targets, including p21, β-catenin, E-cadherin, mitochondrial apoptotic proteins and PPARγ. Our goal was to determine whether alterations in these cellular mediators might be responsible for the observed increase in tumor multiplicity in the colon. We found that sulindac treatment protected against E-cadherin loss in colon tumors, with associated inhibition of nuclear β-catenin accumulation. Importantly, p21WAF1/cip1 and PPARγ expression were absent in colon tumors from sulindac-treated mice, suggesting that loss of these proteins is necessary for lack of response to sulindac. Together, these observations may be translatable to designing novel clinical therapies utilizing combinations of agents that target multiple molecular pathways to overcome sulindac resistance. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 959.