The expression of both peroxisome proliferator-activated receptor delta and cyclooxygenase-2 in tissues is associated with poor prognosis in colorectal cancer patients

Background: The role of peroxisome proliferator-activated receptor delta (PPAR δ) in the development and progression of colorectal cancer (CRC) remains controversial. Aims: We investigated the impact of PPAR δ expression in tissues on liver metastasis of CRC. Methods: We analyzed samples of primary CRC and matched normal adjacent tissues from 52 patients for the expression of PPAR δ, cyclooxygenase (COX)-2, vascular endothelial growth factor (VEGF)-A, and CXC chemokine receptor 4 (CXCR4). Correlations of the molecules expressions with clinical characteristics and prognosis of patients were studied. Results: The number of patients positive for PPAR δ, COX-2, CXCR4, and VEGF-A was 25, 33, 18, and 19, respectively. Among the PPAR δ (+)/COX-2 (+), PPAR δ (-)/COX-2 (+), PPAR δ (+)/COX-2 (-), and PPAR δ (-)/COX-2 (-) patient groups, PPAR δ (+)/COX-2 (+) patients had the highest incidence of liver metastasis (p < 0.01). PPAR δ (+)/COX-2 (+) expression was a significant independent prognostic factor (HR = 7.108, 95% CI 1.231-41.029, p = 0.0283) by Cox proportional analysis. PPAR δ (+)/COX-2 (+) patients had the highest positivity for CXCR4 or VEGF-A in tissues (p < 0.01). Among the patients in the CXCR4 (+)/VEGF-A (+), CXCR4 (+)/VEGF-A (-), CXCR4 (-)/VEGF-A (+), and CXCR4 (-)/VEGF-A (-) groups, CXCR4 (+)/VEGF-A (+) patients had the highest incidence of liver metastasis (p < 0.01). Conclusions: The expression of both PPAR δ and COX-2 in tissues may lead to liver metastasis and consequent poor prognosis in CRC patients.