Prostate-specific membrane antigen (PSMA) immunoexpression in the neovasculature of colorectal carcinoma in Egyptian patients

In Egypt colorectal carcinoma (CRC) is the most common type of malignancy of the digestive system. Selectively inhibiting neoangiogenesis by targeting tumor-associated blood vessels is an important therapeutic strategy. Prostate specific membrane antigen (PSMA) is expressed in the tumor-associated neovasculature of most solid cancers making it an interesting therapeutic target. We thought to study the expression of PSMA in a series of CRCs in order to test for its possible use as a target for antiangiogenic cancer therapy in Egyptian patients. One hundred CRC cases were retrieved. Representative sections from each tumor were subjected to immunohistochemistry using PSMA antibodies and CD31 antibodies as reference marker. Accordingly vascular endothelial cell immunoreactivity was semiquantitatively scored. PSMA immunostaining was positive in the neovasculature of 75% of tumors. A statistically significant relation was found between PSMA immunostaining and distant metastasis as well as vascular invasion. The present findings strengthen the evidence on the potential usefulness of PSMA as a therapeutic vascular target. This study is the first to demonstrate a positive relation between PSMA expression in CRC and distant metastasis as well vascular invasion, suggesting that PSMA may play a significant role in vascular invasion and subsequent metastasis.