Importantly, p21(WAF1/cip1) and peroxisome proliferator-activated receptor-gamma expression were absent in colon tumors from sulindac-treated mice, suggesting that loss of these proteins is necessary for drug resistance.
Colon cancer cases also were less likely to have a tumor with MSI if they had the PA or AA PPARgamma genotype (OR 0.68; 95% CI: 0.47-0.98); differences in Ki-ras mutations were not seen in colon tumors by PPARgamma genotype.
Acromegalic patients have an increased prevalence of colonic neoplasms and lower peroxisome proliferator-activated receptor gamma (PPARgamma) levels, the latter acting as a tumor suppressor gene.