The role of type D prostanoid receptors and PPARγ in gastric cancer progression.

Prostaglandin D2 (PGD2) has been demonstrated to have antitumor effects on cancer cells. PGD2 acts through two major receptors of DP1 and DP2, as well as through the peroxisome proliferator-activated receptor γ (PPARγ) via the PGD2 metabolite, 15-deoxy-Δ12-14-PGJ2. The expression levels of DP1, DP2, and PPARγ were analyzed by immunohistochemistry on 277 primary gastric carcinomas. Either DP1- or DP2-positive cases were regarded as DP-positive. DP-Positive tumour was significantly associated with lymph mode metastasis, lymphatic invasion, and venous invasion. PPARγ positivity was not associated with any clinicopathological factors of gastric cancer. DP-Negative and PPARγ-positive cases were significantly associated with T category, lymph metastasis, and lymphatic invasion. The prognosis of DP-negative and PPARγ-positive cases was better than that of the other cases. These findings suggest that DP and PPARγ signaling influence the invasiveness of cancer cells. DP and PPARγ can be used as a potential marker for gastric cancer progression.