Tumor-associated Stromal Cells Expressing E-prostanoid 2 or 3 Receptors in Prostate Cancer: Correlation With Tumor Aggressiveness and Outcome by Angiogenesis and Lymphangiogenesis

ObjectiveTo clarify the detailed pathologic roles of prostaglandin E2 in prostate cancer tissues, the present study investigated the clinical significance and prognostic roles of the density of tumor-associated stromal cells expressing specific receptors for prostaglandin E2, termed “E-prostanoid (EP)1-4 receptors (EP1R-4Rs).”MethodsThe expression of each receptor was immunohistochemically examined in 114 formalin-fixed biopsy specimens. Correlations with clinicopathologic features were investigated in these specimens. Angiogenesis and lymphangiogenesis were measured by the percentage of CD34-stained vessels (microvessel density) and D2-40-stained vessels (lymph vessel density). The relationships between the density of each EPR-stained cells and the microvessel density or lymph vessel density were evaluated in 62 prostate cancer tissues obtained by radical surgery for more detailed analysis in a wider area of prostate cancer tissue.ResultsThe density of tumor-associated cells with EP2R expression was positively associated with the N (P < .001) and M (P = .002) stages. Similarly, EP3R-positive stromal cell density was significantly associated with the N (P = .033) and M (P = .026) stages. The density of EP2R- and EP3R-stained cells correlated with the microvessel density (r = 0.42, P < .001) and lymph vessel density (r = 0.36, P = .012), respectively. A greater density of EP2R-stained cells was recognized as an independent predictor of progression (hazard ratio 7.26, P = .002) on multivariate analysis.ConclusionEP2R- and EP3R-stained cells might play important roles in tumor progression, angiogenesis, and lymphangiogenesis in prostate cancer. The density of EP2R-stained stromal cells could offer a useful predictor of biochemical recurrence after radical surgery.