Expression of Peroxisome Proliferator-Activated Receptor-γ in Colon Cancer: Correlation with Histopathological Parameters, Cell Cycle-Related Molecules, and Patients’ Survival

摘要

Peroxisome proliferator-activated receptor γ (PPAR-γ), a ligand-activated transcription factor, is a key regulator of adipogenic differentiation and glucose homeostasis. PPAR-γ ligands have recently been demonstrated to affect proliferation and differentiation in cancer cells lines. The aim of the present work was to examine PPAR-γ expression in colon cancer cases. PPAR-γ expression was examined immunohistochemically in 86 colon cancer cases and was correlated with clinicopathological parameters, tumor proliferative capacity, cell cycle-related molecule expression, and patient survival. Positive PPAR-γ immunostaining was prominent in 48 of 86 cases (56%). PPAR-γ positivity was not correlated with Dukes’ stage, histological grade of differentiation, lymph node and liver metastasis, venous invasion, tumor proliferative capacity, or patient survival. A statistically significant correlation was found between PPAR-γ and the expression of cell cycle-related molecules pRb (P < 0.016), cyclin D1 (P <0.009), p16 (P<0.032), and p21 (P<0.033), while a positive trend for cyclin E was also noted (P<0.057). The pattern, intensity, and extent of PPAR-γ expression in positive cases were not correlated with any of the examined variables. Our findings support evidence for participation of this protein in the biological mechanisms underlying carcinogenic evolution in the colon, also suggesting the importance of specific PPAR–γ ligands as cell cycle modulators for a future therapeutic approach in colon cancer.