Endoglin (CD105) is expressed on immature blood vessels and is a marker for survival in prostate cancer

Background. Endoglin, a receptor for some of the members of the transforming growth factor-beta (TGF-beta) family, is expressed on proliferating endothelial cells and has been suggested as a marker of ongoing angiogenesis. In this study, endoglin was evaluated as a prognostic factor for prostate cancer progression. Methods. Immunohistochemical staining of endoglin was examined in 72 cases of prostate cancer and compared with immunohistochemical staining of the pan-endothelial marker von Willebrand factor (vWf), clinicopathological factors, and cancer-specific survival. Microvessels were measured in the most vascularized fields. Double staining with antibodies against smooth muscle actin and endoglin or vWf, respectively, was performed in order to evaluate vessel maturation. Results. Endoglin-stained tumor vessels were generally small and only 19% also stained with actin. Endoglin was a better prognostic marker than vWf. The median survival times were shorter for patients with tumor vascular count (vc) above median than for patients with vc below median (4 vs. 12 years, P=0.0007, and 5 vs. 10 years, P=0.018, for endoglin and vWf, respectively). Endoglin vc was associated with Gleason score (P=0.001), local tumor stage (P=0.0006), metastasis (P=0.01), tumor cell immunoreactivity for TGF-beta1 (P=0.0003), and tumor cell proliferation index (r(s)=0.319, P=0.02). Endoglin, in contrast to vWf, vc was prognostic for survival in the subgroup of patients with Gleason score 5, 6, and 7 tumors. Conclusions. Endoglin marks principally small, probably newly formed tumor vessels in zthe prostate, and is a promising prognostic marker for prostate cancer patients.